Space science - NSW Department of Education

Transcription

Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
0
0
2
I
SSCHSC43172
2
er
b
to T S
c
O EN
g
in D M
t
a
r EN
o
p
or AM
c
n
P0025975
Number: 43172
Title: Space science
This publication is copyright New South Wales Department of Education and Training (DET), however it may contain
material from other sources which is not owned by DET. We would like to acknowledge the following people and
organisations whose material has been used:
Photograph of a lunar landing module courtesy of Rhonda Caddy
Part 4 p 20
Photograph of dish of the Parkes radio telescope © Baska Bartsch, 1997
Part 5 p 14
COMMONWEALTH OF AUSTRALIA
Copyright Regulations 1969
WARNING
This material has been reproduced and communicated to you on behalf of the
New South Wales Department of Education and Training
(Centre for Learning Innovation)
pursuant to Part VB of the Copyright Act 1968 (the Act).
The material in this communication may be subject to copyright under the Act.
Any further reproduction or communication of this material by you may be the
subject of copyright protection under the Act.
CLI would also like to thank the following people who have contributed to the development of this resource:
Writer(s):
Steven Vassallo and Jeanette Rothapfel
All reasonable efforts have been made to obtain copyright permissions. All claims will be settled in good faith.
Published by
Centre for Learning Innovation (CLI)
51 Wentworth Rd
Strathfield NSW 2135
_______________________________________________________________________________________________
_
Copyright of this material is reserved to the Crown in the right of the State of New South Wales. Reproduction or
transmittal in whole, or in part, other than in accordance with provisions of the Copyright Act, is prohibited without the
written authority of the Centre for Learning Innovation (CLI).
© State of New South Wales, Department of Education and Training 2008.
Contents
Module overview ........................................................................iii
Resources............................................................................................ iii
Icons .....................................................................................................v
Glossary............................................................................................... vi
Part 1: Up into thin air .........................................................1–29
Part 2: The strength of gravity in space...............................1–26
Part 3: Living in space.........................................................1–29
Part 4: Rockets and shuttles ...............................................1–30
Part 5: Space exploration....................................................1–41
Part 6: Space technology and society .................................1–20
Student evaluation of the module
Introduction
i
ii
Space science
Module overview
Ideas and information about space are commonly reported in the mass
media. From childhood, people seem to be fascinated with what we can
and cannot see in the night sky. This unit investigates some of the
common areas of space science, including ideas about the atmosphere,
gravity, space exploration and how space research impacts on society.
Resources
You will need the following equipment to carry out activities and
experiments during the module. In most cases, you should have the
items listed around your home. If not, items can be easily obtained, with
little expense.
Internet access is needed for Parts 2, 3, 4, 5 and 6.
Part 1
•
glass
•
soft rag
•
plastic wrap
•
refrigerator with freezer
•
frozen peas
•
1 m ruler with a hole in the centre (or a similar piece of wood)
•
wire coat hanger
•
2 identical balloons
•
sticky tape
Part 2
•
Introduction
disposable foam cup
iii
Part 3
•
glass
•
stick, such as a broom handle
•
strip of rubber, such as an old bicycle tyre inner tube
•
medical thermometer
Part 5
•
piece of clear plastic
Part 6
iv
•
raw potato
•
plastic straw
•
2 identical long balloons
•
3 large rubber bands
Space science
Icons
The following icons are used within this module.
The meaning of each icon is written beside it.
The hand icon means there is an activity for you to do.
It may be an experiment or you may make something.
You need to use a computer for this activity.
Discuss ideas with someone else. You could speak with
family or friends or anyone else who is available.
Perhaps you could telephone someone?
There is a safety issue that you need to consider.
There are suggested answers for the following questions
at the end of the part.
There is an exercise at the end of the part
for you to complete.
Introduction
v
Glossary
The following words, listed here with their meanings, are found in the
learning material in this module. They appear bolded the first time they
occur in the learning material.
vi
astronomy
the scientific study of objects (such as stars,
planets and comets) outside of Earth’s
atmosphere
atmosphere
the thin layer of gases that surround a planet,
such as Earth
atrophy
the wasting away of a body part; when a body
part becomes smaller because of lack of use
or illness
celestial
in the sky; describing a natural object away
from Earth
circadian rhythms
patterns in body processes that recur
approximately every 24 hours
comet
an object, mostly composed of ice, that orbits
the Sun; it has a vapour tail that always
streams away from the Sun
concentration
a measure of the amount of one substance in a
volume or in a mixture
density
a measure of the amount of matter in a
volume; mathematically, density equals mass
divided by volume
EVA
extravehicular activity; a spacewalk
friction
the force of resistance when one object moves
against another
galaxy
a very, very large grouping of stars, held
together by gravitation and distinctly
separated from another large grouping of stars
GBS
ground-based satellites; the name given to
telescopes on Earth that work in partnership
with space-based satellites/telescopes
gravitation
attraction that exists between any objects due
to their mass
gravity
attraction that exists between objects with
mass; on the surface of planet Earth gravity is
the attraction of the Earth for an object
HALCA
Highly Advanced Laboratory for
Communications and Astronomy; a spacebased radio telescope
Space science
Introduction
hormone
a chemical messanger carried throughout the
body in body fluids, usually blood
ingestion
the taking of substances into the body
intergalactic space
a description of the volume between galaxies
interplanetary space
a description of the volume between planets
interstellar space
a description of the volume between stars
ISS
International Space Station; a space station
currently being constructed as it orbits Earth
lift-off
the start of a rocket’s launch when it rises
from the ground
micrometeoroid
tiny meteoroid; small pieces of sand or rock
travelling in space
momentum
a measure of the movement of an object;
mathematically, momentum = mass ¥ velocity
nebula (plural nebulae)
a cloud of dust and gases in space
orbit
the curved path of an object as it travels
around a central object; for example, the path
of a planet around the Sun or the path of the
Moon around Earth
OSETI
Optical Search for Extraterrestrial
Intelligence; a project looking for intelligent
life in the Universe by making observations
using light
pulsar
a pulsating star; a star that emits radio waves
radio telescope
a device used to gather radio waves from
objects in space (including stars, spacecraft
and artificial satellites)
rate
a comparison of the change in one thing and
another thing; often refers to the amount of
change in one thing over time
re-entry
the return of a spacecraft into Earth’s
atmosphere
reflecting telescope
a device that uses mirrors to gather light
waves, forming images of distant objects
refracting telescope
a device that uses lenses to gather light waves,
forming images of distant objects
refurbishment
the renovation of an object for reuse
vii
viii
revolution
when an object completes one entire circuit;
for example, the travel of Earth around the
Sun once each year
RLV
Reusable Launch Vehicle
rocket
a structure with an engine that can exert a
thrust force and so be fired into the air; for
space exploration, a rocket carries its own
fuel and oxygen
satellite
an object that revolves around another; for
example, the Earth is a natural satellite of the
Sun
SETI
Search for Extraterrestrial Intelligence; a
project looking for intelligent life in the
Universe by making observations using radio
waves
solar system
the group of planets, moons, asteroids and
comets that revolve around the star called the
Sun
space-time
a fourth dimension used in Einstein’s
theories; it relates a three dimensional volume
or object to a given time
spin-off
an object, product or process that results from
another purpose
SRB
Solid Rocket Booster
STS
Space Transportation System; a name given
to the space shuttle
supernova
(plural supernovae)
a gigantic, violent explosion of a large star,
giving out lots of light
telemetry
the automatic measurement and relaying of
information over large distances
theory
a scientific explanation based on many
observations and ideas, and used to make
predictions that have been tested in many
experiments
thrust
the backwards force that causes a rocket to
move forwards
VLBA
Very Long Baseline Array; the name for a
group of ten radio telescopes based in North
America that cooperate together to synthesise
a much larger radio dish
Space science
Introduction
VLBI
very long baseline interferometry; a technique
of using several receivers (telescopes or
dishes) at separated locations to collect
information, then combining the information
to produce a much clearer or more detailed
image of the object being observed
weightlessness
the feeling that you do not have weight; it
occurs when an object is falling; sometimes
called microgravity
ix
Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
Part 1: Up into thin air
0
20
I
er
b
to T S
c
O EN
g
ti n D M
a
r
o EN
p
r
o AM
nc
2
Gill Sans Bold
Contents
Introduction ............................................................................... 2
The atmosphere ........................................................................ 4
What is the atmosphere like? ..............................................................4
The outer limits of the atmosphere......................................................6
Modelling density....................................................................... 9
The particle theory of matter................................................................9
Distances between particles ..............................................................10
Comparing densities .........................................................................15
How is the atmosphere held in place?..................................... 19
Suggested answers................................................................. 23
Exercises – Part 1 ................................................................... 27
1
Introduction
Have you ever lain back, looked up at the deep blue sky and wondered
how far up it goes? Have you wondered why mountain climbers find it
harder and harder to breathe as they climb up higher and higher?
The explanations have something to do with that expression, ‘up into
thin air’.
You already know that air gets ‘thinner’ as you go higher but what does
this mean? The first section of this part explores the extent of the
atmosphere in terms of the distribution or concentration of particles.
How far up would you have to go before space begins and the
atmosphere ends? You will be able to compare the composition of
different parts of space with the upper limits of the atmosphere so that
you can discuss why there is no such thing as ‘empty space’.
Then you will make and use a model of matter to help you to explain
some similarities and differences of solids, liquids, gases and ‘space’.
People say that Earth’s gravitational pull really sux but if it didn’t,
where would the atmosphere go? In the last section of this part,
you’ll learn about how the atmosphere is maintained in place by
Earth’s gravitational pull.
You will need to start gathering some equipment, such as a coat hanger,
two balloons, sticky tape and either a metre ruler with a hole in the centre
(at 50 cm) or a similar piece of wood. This equipment is for an activity
to demonstrate that air has weight. That is an important property of air
that you need when identifying how the atmosphere is held around Earth.
In this part you will be given opportunities to learn to:
2
•
discuss the concept of the atmosphere in relation to the distribution
or concentration of particles of gas
•
identify that the Earth’s atmosphere is largely maintained in place by
the earth’s gravitational pull
•
discuss why there is no such thing as ‘empty space’.
Space science
Gill Sans Bold
You will have opportunities to:
•
gather, process and present information from secondary sources to
model the relative distance of particles in a solid, liquid, gas and in
space.
Extracts from Senior Science Stage 6 Syllabus © Board of Studies NSW,
October 2002. The most up-to-date version is to be found at:
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
3
The atmosphere
You probably know by now that an atmosphere surrounds Earth.
What is the atmosphere like?
The atmosphere is a mixture of gases and does not go on forever.
It forms a thin layer that separates outer space from Earth’s surface.
In fact, seen from outer space, Earth’s atmosphere is just a thin shell.
atmosphere
Russian supply rocket
space
International
Space Station
Earth
Earth
atmosphere
Look at the diagram. The thickness of the atmosphere is much, much less
than the thickness of the Earth. The atmosphere is about as thin as the crust
on a slice of bread.
You can see the atmosphere getting thinner as you move away from Earth.
This basically means that the distance between particles in air increases with
altitude (height above Earth’s surface.)
The part of the atmosphere that we live in and where all weather occurs
is only about 12 km thick. It comprises 85% of the gas particles in
the atmosphere.
4
Space science
Gill Sans Bold
Distribution of air particles in the atmosphere
The diagram below shows the distribution of air particles in the
atmosphere from ground level to outer space. Look at how close
together the dots in the diagram are.
outer space
10 000
9 000
Distance (km)
8 000
not to scale
7 000
100
12
ground level
Describe, in your own words, what happens to the space between air
particles as altitude increases.
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
What changes occur to air as you get higher and higher above sea level?
Mountaineers complain about shortness of breath. High altitude pilots
carry oxygen to breathe. People say the air is thinner at great heights.
This means that air particles are further apart. There is less and less air
for people to breathe as altitude increases.
5
A more scientific way of describing the distance between particles in air
is to refer to the density of air in the atmosphere.
Density of air in the atmosphere
Density is the mass per volume of a substance so it is an ideal property to
use when discussing the distribution or concentration of air particles.
A mass that is concentrated in a small volume has a greater density than a
substance of equal mass that occupies a larger volume. Thus, gases
have the smallest densities when compared with solids and liquids.
Gases contain mostly empty space so a fixed amount of mass fills a large
amount of space. In liquids and solids, particles are more tightly packed
together so that the same fixed amount of mass occupies a much
smaller space.
How does the density of air in the atmosphere change as altitude increases?
_________________________________________________________
_________________________________________________________
Check your answer.
The outer limits of the atmosphere
There is no point at which you can say the atmosphere ends and
space begins.
A vacuum is a space that contains no matter; there is no mass present in a
given volume. It is a completely empty space.
Space is called ‘space’ because it contains very little matter. But it is not
a perfect vacuum. (However, it is a better vacuum than the best ones
made in laboratories on Earth.)
Space contains tiny particles, mostly lone atoms of hydrogen and other
elements such as helium.
The density of particles in space varies, depending on the part of space
that you are talking about. For example, the space just outside Earth is
similar to the space between planets. It is called interplanetary space.
6
Space science
Gill Sans Bold
Venus
Mars
Saturn
Neptune
Sun
Mercury
Earth
Uranus
Pluto
Jupiter
Interplanetary space separates planets in the Solar System. Note that this
diagram is not drawn to scale.
At a height of about 10 000 km above Earth’s surface, the density of air
in the upper atmosphere becomes equal to that of interplanetary space.
Hence, the atmosphere has no definite outer boundary. As it extends
outwards from Earth, the atmosphere becomes thinner and thinner
(less and less dense) and gradually blends with particles of space.
The density of interplanetary space is about 5 to 10 atoms per
cubic centimetre (cm3). This density can also be reported as
5 to 10 million atoms per cubic metre (m3). A star at the centre of the
solar system (the Sun) releases most of this matter into space.
What happens to the composition of space as you move away from a star
such as the Sun?
The space between stars is called interstellar space. It contains a very
small number of hydrogen atoms. Interstellar space has an average
density of about 1 atom per cm3 (or one million atoms per m3.)
Galaxies tend to have a centre, or galactic core. At the core of a galaxy,
the density of matter can be as high as 1 000 atoms per cm3 (1 billion
atoms per m3.)
But in the extreme depths of space, in the huge spaces between galaxies,
densities as low as 0.1 atoms per cm3 (or 100 000 atoms per m3) have
been found. These very low density regions between galaxies are called
intergalactic space.
7
A typical spiral galaxy.
The density is highest at the core and gets less as you move outwards.
Complete Exercise 1.1 now.
8
Space science
Gill Sans Bold
Modelling density
You have learnt that the density of matter in space varies. Density is
greatest near the centre of a galaxy and least in the space between
galaxies. You have also found out about the way the density of the
atmosphere decreases with altitude.
In this section, you are going to make and use a model of matter to
help you to picture the differing densities of solids, liquids, gases and
space. You have to think of matter as made of tiny particles (the particle
theory of matter) and you have to think about how close together these
particles are (the distances between particles.)
The particle theory of matter
The particle theory of matter states that all substances are made of tiny
ball-like pieces, or particles. These particles move and interact with each
other. The theory explains why liquids and gases do not have their own
shape and why gases can be compressed but liquids and solids can’t.
It also explains what happens when substances change state.
For example, you can freeze water to change it into a solid but it can melt
and changes back to water. The difference between solid water (ice) and
liquid water is the way that the particles in water are arranged.
In the following activity, you will model the relative distances between
particles for the different states of matter. Then you will go one step
further and compare these distances with the distances between particles
in space.
9
Distances between particles
For this activity, you will need:
•
a glass
•
a soft rag
•
plastic wrap
•
the freezer in a refrigerator
•
some round things. (Frozen peas are best.)
What if…
Only the largest microscopes let people see the particles that make up
matter. But long before this was possible, scientists wondered, ‘what if we
think of a substance as balls? What if the balls don’t change when the
substance changes state? Only the arrangement of the balls will change.’
In other words, they created a model – a way to help them picture and
explain what was happening.
Frozen peas are ideal for this model but if you don’t have peas or don’t
want to use food, you can use other things, such as small balls of
plasticine or marbles and blue tack. If you are using frozen peas,
check that this is OK because you will have to throw them away after
the experiment.
Modelling a gas
What to do:
The procedure below assumes you are using frozen peas and a glass.
If you are using other materials, adjust the procedure to fit your materials.
Each pea in this experiment represents the smallest piece of a substance.
You can think of each pea as a particle of water or a particle in air.
10
•
Scrunch the packet of frozen peas before you open it so that you
break up any clumps. Don’t squeeze so hard that you burst the bag!
•
Pour frozen peas into the glass to a depth of about 3 cm. Wrap the
glass in plastic wrap, making sure that you can still see into the side
of the glass.
Space science
Gill Sans Bold
Here is a photograph of a flask of gas. Notice that there is a cork in the
top of the flask to stop the coloured gas from escaping.
(Photo: ”LMP)
1
What could be happening to the particles of gas in order for it to fill
the entire flask?
_____________________________________________________
_____________________________________________________
2
What could you do with your glass of peas to make it resemble the
gas in the flask?
_____________________________________________________
_____________________________________________________
Did you think of shaking the glass of peas? Try it. But if you are using
hard balls such as marbles, DON’T.
You need to be careful not to knock the glass too hard or it may break and
broken glass can be dangerous. (You wouldn’t have the glass any more either!)
Did you notice that peas fly about everywhere inside the glass when you
shake it? Everywhere in the glass has some peas but there is lots of
space between them.
Can you use this model to explain what a gas is like?
11
Do you remember what a gas is like? A gas does not have its own shape
and it is easy to compress.
3
Here is a ‘snapshot’ of the peas while you
were shaking the glass.
a) Would the peas still go everywhere
inside a container that was of a
different shape?
_______________________________
b) Could you compress (squash) the peas
closer together?
_______________________________
Did you decide that the model of the peas in the glass explains what a gas
is like? When you shake the container, the pea ‘gas’ will be whatever
shape the container is. And the pea ‘gas’ can be compressed because
there is lots of space between the peas.
Using the particle model, you can think of a gas as lots of balls (particles)
flying around and bouncing off each other and the sides of the container.
You can explain some observations about a gas by using this model.
Modelling a liquid
What to do:
1
Slowly turn the glass of peas over and over. Describe what you see
happening inside the glass.
______________________________________________________
______________________________________________________
2
Stop the glass in any position. What shape do the peas make?
______________________________________________________
______________________________________________________
3
How is this like a liquid?
______________________________________________________
______________________________________________________
12
Space science
Gill Sans Bold
The particles in a liquid are able to move over each other so that a liquid always
fills the bottom of its container.
4
Another property, or feature, of a liquid is that it cannot be
compressed. Look at the peas in your glass. Is there much space
between them?
_____________________________________________________
_____________________________________________________
5
Use the particle model to explain why a liquid cannot be
compressed.
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Modelling a solid
What to do:
Gently tap the base of the glass so that the peas pack together.
There should not be much space between the peas.
Your peas have probably begun to melt. (That’s good!) Keep the glass
steady so that the peas stay in the pattern and put the glass into the
freezer. If you are using balls of plasticine, press them gently together.
If you are using marbles, use blue tack to stick the marbles together into
a clump.
Check your model after about 20 minutes. You’ll find that the peas have
stuck together into a solid. You can shake the solid out of the glass and
hold it. It has its own shape because all the particles (peas) are held in
position in the pattern.
13
Put the block of peas back into the glass. Look through the side of the
glass at the pattern made by the peas.
Circle the pattern below that is most like your peas.
A
B
C
Did you think that the peas look most like A? If yours look like C
then you haven’t broken up the lumps or you haven’t tapped the glass
for long enough.
Is there any space between the peas to be able to compress them (without
squashing the peas themselves)? No. Thus, the model lets you explain
why solids cannot be compressed.
Modelling particles in space
Yes, there are particles of matter in space; there are not very many of
them but they do exist. They are usually in the form of individual atoms
or just nuclei of atoms.
How could you model these particles? Try to devise your own model
using your glass and peas.
How many peas would you put into the glass to model particles in:
a)
interplanetary space? _________
b) interstellar space? ____________
c)
intergalactic space? __________
Please read the comments in the suggested answer pages.
14
Space science
Gill Sans Bold
Comparing densities
1
2
Complete the diagrams below to model the densities of a solid, a liquid,
a gas and ‘space’.
solid
liquid
gas
space
Now compare the distances between particles in these models.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Air at sea level has the same composition as air on mountain tops.
However, air at sea level has more air particles packed into a given
space, making it denser than air at the tops of mountains. If you go even
higher then air gets less and less dense until it is so ‘thin’ that it is almost
a vacuum.
How fast does air density drop off as you go up through the atmosphere?
You can visualise this by completing the next activity that asks you to
graph data about the density of air compared with its altitude.
15
The table below shows values for the density of air (in grams per cubic
metre) at altitudes that are 5 kilometres apart.
Density of the atmosphere at heights above sea level
Density
(g/m3)
16
Altitude
(km)
1250
0
740
5
410
10
190
15
82
20
41
25
18
30
9.6
35
4
40
2
45
1
50
0.56
55
0.31
60
0.16
65
0.08
70
0.04
75
0.018
80
0.01
85
Space science
Gill Sans Bold
3
Use the graph paper below to plot the data points from the table.
Note:
The scale provided on the X-axis will cause the last ten data
points to look as though they have the same X value of zero.
Graph of density of the atmosphere at heights above sea level
90
80
70
Altitude (km)
60
50
40
30
20
10
0
100
200
300
400
500
600
700
800
Density (g/m3)
900
1000
1100
1200
1300
1400
Compare your graph with the one in the suggested answer pages.
Questions about the graph
Now use information from the table and your graph to answer the
questions below. (Remember that density = mass ÷ volume).
4
What is the mass of a cubic metre of air at:
a) sea level?
_________________________________________________
b) an altitude of 50 kilometres?
_________________________________________________
5
The tallest mountain on Earth’s surface is Mount Everest.
It is nine kilometres above sea level.
What is the density of air at the top of Mount Everest?
_____________________________________________________
17
6
Aircraft engines need air to keep the fuel burning.
Planes can fly up to a minimum air density of about 200 g/m3.
Above this height there is not enough air to sustain the engines.
Up to what altitude can aircraft fly?
______________________________________________________
7
Look again at the shape of the graph that you drew. Then describe
how the density of air changes as altitude increases.
______________________________________________________
______________________________________________________
______________________________________________________
Check all of your answers.
Then complete Exercise 1.2.
18
Space science
Gill Sans Bold
How is the atmosphere
held in place?
The atmosphere is largely held to the surface of Earth because of
gravity. Gravity causes objects (including atoms and molecules) to have
weight. Weight is a force pulling objects that have mass downwards
towards the centre of Earth. (Part 2 explains this further). Weight can
also be described as a force caused by the gravitational pull of Earth.
Is it hard to imagine that air has weight? Even though it is made up of
gas particles bouncing about at speeds of up to 2 000 km/hr, the particles
in air are attracted to Earth by gravity, causing them to have weight.
One cubic metre of air at sea level has a mass of 1.25 kilograms.
The weight of this cubic metre of air is commonly called 1.25 kg
meaning that it has a weight force equal to that of a 1.25 kg mass.
Most gases in the atmosphere are concentrated at the Earth’s surface
where the gravitational force is strongest. This is why air is most dense
at sea level. Only light gases, such as hydrogen, made up of tiny gas
molecules moving at high speeds, overcome the gravitational pull
of Earth.
You can demonstrate that air has weight by measuring the weight of
an empty balloon then filling it with air and weighing it again.
The following activity demonstrates that air has weight.
Does air have weight?
The aim of this activity is to demonstrate that air has weight.
•
a 1 metre ruler with a hole in the centre (at 50 cm) or a similar piece of wood
•
1 wire coat hanger
•
2 balloons (Identical ones are best.)
•
sticky tape
•
the edge of a table.
19
What to do:
Set up your equipment on a table as follows.
books
table
coathanger
deflated
balloon
deflated
balloon
wood
or
metre ruler
Lay the coathanger flat on the table. Straighten out the hook part of the
coathanger so that it pokes out past the table edge. Place a heavy object
such as a book on the coathanger to keep it firmly in place on the table.
Using the sticky tape, position a balloon (not blown up at this stage)
on either end of the ruler so that the ruler is balanced and level.
Mark the positions of the balloons.
Remove one balloon and inflate it. Then stick the inflated balloon back
onto its mark on the ruler. It must be in exactly the same position as before.
Result:
You should have observed that the inflated balloon is pulled down
further than the deflated balloon.
books
table
coathanger
deflated
balloon
20
wood
or
metre ruler
inflated
balloon
Space science
Gill Sans Bold
1
Explain why the ruler does not remain level and balanced when
one balloon is inflated.
_____________________________________________________
_____________________________________________________
_____________________________________________________
2
Describe what you understand by weight, using the word force.
_____________________________________________________
_____________________________________________________
_____________________________________________________
3
Here is a harder question.
The atmosphere is much thicker at the equator than at the poles.
atmosphere thin at poles
the atmosphere is five times
thicker at the Equator
The way that Earth spins is used to explain the change in thickness.
Explain how a spinning Earth causes the atmosphere to be thicker at
the equator and thinner at the poles.
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Now you are ready to complete the final exercise for Part 1.
Do Exercise 1.3 now.
21
22
Space science
Gill Sans Bold
Suggested answers
Distribution of air particles in the atmosphere
The distance between air particles increases with altitude.
(Air particles are further apart the higher you go above ground level.)
Density of air in the atmosphere
The density of air decreases with altitude.
(Air particles are further apart so there is less mass of air per volume
the higher you go above ground level.)
Modelling a gas
1
The particles of gas could be ‘flying’ around inside the flask.
2
Shake it in all directions to make the peas move about.
3
a) Yes, the peas go into every part of the container no matter what
its shape.
b) Yes, the peas could be compressed into a smaller volume
because there are large distances between them.
Modelling a liquid
1
The peas are rolling around inside the glass.
2
The peas take whatever shape is at the bottom of the container.
3
This is like a liquid because a liquid does not have its own shape.
Instead, a liquid takes the shape of the bottom of the container.
4
No, the peas are close together.
5
The distances between particles in a liquid are small so the particles
cannot be pushed closer together. (The liquid cannot be
compressed.)
23
Modelling a solid
Your model should look like A.
Modelling particles in space
Space contains very few particles. Even one pea in your glass is too
much matter to represent particles in space. However, if you have to use
this model, you could use:
a)
5 peas (to represent 5 to 10 atoms per cm3 of interplanetary space)
b) 1 pea (to represent 1 atom per cm3 of interstellar space)
c)
a tiny piece of pea (to represent 0.1 atoms per cm3 of intergalactic
space).
Comparing densities
1
The solid will contain ‘balls’ arranged
tightly together. The solid can have its own
shape.
The liquid will contain ‘balls’ that are very
close together but not in a fixed pattern.
They will take the space of the bottom of the
container.
The gas will contain ‘balls’ that are as
far apart as possible. The gas will fill the
container.
Space will contain a very small amount of
matter only.
2
24
Particles in space are the furthest apart. Particles in a solid are the
closest together. Particles in a liquid are close together (though not
usually quite as close as those in solids) and particles in gases are
further apart (though nowhere near as far apart as those in space).
Space science
Gill Sans Bold
3
This is how your graph should look.
Note: This graph has been drawn using a computer spreadsheet.
Since you have drawn your graph by hand, your points should be
marked with neat crosses.
Graph of density of the atmosphere at heights above sea level
90
80
70
Altitude (km)
60
50
40
30
20
10
0
100
4
200
300
400
500
600
700
800
Density (g/m3)
900
1000
1100
1200
1300
1400
a) 1.25 kg (1 250 g)
b) 1 g
5
about 450 g/m3
6
about 14 km
7
As altitude increases, the density of air decreases.
(As the height above sea level gets larger, the density of air
gets smaller.)
But you could also describe a graph in this way if it was a straight line
that sloped down towards the right hand side. So if you want to give a
better description of this graph, you’d say that as altitude increases
density decreases exponentially.
The relationship could be represented by a proportionality such as
1
k
altitude µ
.
2 or an equation such as altitude =
density 2
density
25
Does air have weight?
1
The inflated balloon (with the air in it) is pulled down more than the
deflated balloon. The inflated balloon is said to have more weight.
2
Weight is a force caused by gravity. The gravitational force called
weight pulls an object towards the Earth.
3
Matter on the surface of a spinning object will experience a force
away from the axis of rotation. The further away from the axis,
the greater the force will be and the equator is the furthest away from
Earth’s axis.
It is like when you are spinning around on a roundabout or a
sideshow ride. As you spin around, you can feel yourself being
thrown out away from the middle of the roundabout. The further
you are from the middle of the roundabout, the more you feel the
force.
You don’t really need to understand why the atmosphere bulges at
the equator. But if you can explain it, you probably can also identify
that the atmosphere stays in place around Earth because gravity pulls
on air particles, giving them weight directed towards the centre of
the Earth.
26
Space science
Gill Sans Bold
Exercises – Part 1
Exercises 1.1 to 1.3
Name: _________________________________
Exercise 1.1
a)
Mountain climbers will tell you that it gets harder to breathe the
higher up they go. Why is this?
_____________________________________________________
_____________________________________________________
_____________________________________________________
b) How does the density of air at 10 000 km differ from the density of
air in interstellar space?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
c)
Describe how the distribution of air particles changes between
Earth’s surface and the Moon. (The Moon has no atmosphere and is
about 400 000 km from the Earth.)
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
27
Exercise 1.2
a)
Plot points for the information in the table below onto the graph grid.
Object
Height above sea level
(km)
Mount Everest
9
cirrus clouds
10
passenger jet
12
spy plane
30
weather balloon
40
visible meteor showers
50 to 80
first American in space
190
northern lights (aurora)
180 to 190
first Russian in space
low orbit satellites
200
220 to 240
space shuttle
250
260
240
220
Height above sea level (km)
200
180
160
140
120
100
80
60
40
20
0
Object
28
Space science
Gill Sans Bold
b) Can you draw a line across your graph to show where you think
space ‘starts’? Justify your answer.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
c)
Evaluate whether there is such a thing as ‘empty space’.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Exercise 1.3
a)
Why does the atmosphere stay in a thin shell around Earth?
_____________________________________________________
_____________________________________________________
_____________________________________________________
b) Explain why hardly any hydrogen gas, H2(g), or helium gas, He(g),
is retained in the Earth’s atmosphere for any length of time.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
29
Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
Part 2: The strength of gravity in space
0
20
I
er
b
to T S
c
O EN
g
in D M
t
a
r EN
o
p
or AM
c
n
2
Gill Sans Bold
Contents
Introduction ............................................................................... 2
Mass and gravitational pull........................................................ 3
Mass causes gravity….........................................................................5
So what is gravity? ...............................................................................7
Falling into orbit ......................................................................... 9
Falling around Earth.............................................................................9
Falling around the Sun.......................................................................12
Artificial satellites are falling too ........................................................14
Environments of negligible gravity........................................... 15
Developing the idea of weightlessness .............................................16
Experiencing weightlessness .................................................. 19
Animals in space ..................................................................... 21
Exercises – Part 2 ................................................................... 25
1
Introduction
For as long as thinking humans have existed, the question. ‘What makes
objects fall?’ has been pondered. In this part, you will learn about
gravity. You’ll see why an understanding of gravitational force is
important in space exploration.
All objects in the Universe are attracted to each other by gravitation,
from the smallest particles to the largest celestial bodies. The most
fundamental evidence that gravitational attraction exists is at the surface
of Earth. The force holding objects and the atmosphere to Earth is the
same as the one that causes objects to fall.
You will need to collect a disposable foam cup for an activity within
this part.
•
identify the relationship between mass and gravitational pull and
relate this to the revolution of the Moon around Earth and the
revolution of the planets around the Sun
•
identify situations on Earth where one could experience
‘weightlessness’
•
discuss the reasons for the apparent weightlessness of an object in
orbit.
•
identify and discuss the reasons why animals have been sent into
space before humans
2
Space science
Gill Sans Bold
Mass and gravitational pull
When the first astronomers studied the wanderings of the planets, they
must have thought about what causes them to move about. They devised
ways of accurately describing their movements and predicting their
positions. However, it took until the middle of the seventeenth century
before scientists explained that gravitation causes their motions.
Galileo
Around the middle of the seventeenth century, the famous scientist
named Galileo discovered that all objects fall at the same rate. Legend
says that he demonstrated this by dropping a large ball and a small ball
off the Leaning Tower of Pisa.
3
The crowds were astonished when the balls hit the ground at the
same time. The mass of each object had no effect on its rate of falling,
showing that gravity was something that was constant for objects
on Earth.
This experiment was repeated on the Moon during the Apollo 15 mission
where astronaut David Scott dropped a hammer and a feather, which both
fell to the ground (on the Moon) at the same rate. You can access a video of
the actual experiment at: http://www.lmpc.edu.au/Science
Newton
In 1666, Isaac Newton, at the age of 24, made calculations of the rate at
which an apple falls to the ground. He suggested that the gravitational
force causing apples to fall towards Earth and rocks to fall from the tops
of mountains is the same force that causes the Moon to orbit Earth.
The Moon, the rock and the apple are all attracted towards Earth because
of its gravitational pull.
How does this happen?
4
Space science
Gill Sans Bold
Mass causes gravity …
Earth’s gravitational pull causes objects to fall toward its centre. This is
why you, and every other object on Earth, are pulled down onto its
surface. Newton realised that the planets and the Sun and all celestial
objects are influenced by gravitation.
One way to think about gravitation is to imagine it acting in a force field.
You may be familiar with the term ‘force field’ as a zone or place where
an object experiences a force. There are force fields around magnets and
electrically charged objects. Similarly, there are force fields called
gravitational fields around objects, including stars and planets.
The larger the mass of an object, the greater its gravitational pull
Which one would you expect to exert a stronger gravitational pull on a
nearby object – Earth or the Sun? Did you say, the Sun? The Sun has much
more mass than Earth so there is more gravitational attraction between the
Sun and an object than between Earth and the object when the object is the
same distance from the Sun and the Earth.
Earth
Sun
gravitational attraction
between objects with mass
There is more gravitational pull between the object and the massive Sun when
the object is the same distance from both the Sun and the Earth.
Gravitation occurs near any object that has mass; gravity is the special
name for gravitation on Earth. (Sometimes the words gravity
and gravitation are used in place of each other.)
5
…and gravity causes weight
Weight is a force pulling the mass of
an object down. An object has weight
when it is influenced by gravity.
A big mass weighs more than a small
mass in the same gravitational field.
Gravitational pull is a term used to
describe the force that an object
experiences in a gravitational field.
On Earth, gravitational pull is the same
as weight.
body
mass
gravity
weight = mass x gravity
The table below provides information about the mass of some objects in
the Solar System. The masses are shown using scientific notation.
For example, Earth’s mass is 6.03 ¥ 1024 kg which means
6.03 ¥ 1 000 000 000 000 000 000 000 000 (24 zeros!)
The mass of some objects in the Solar System
Object
Mass
(kg)
Sun
2.00 ¥ 1030
Earth
6.03 ¥ 1024
Moon
7.4 ¥ 1022
Jupiter
1.9 ¥ 1027
Use the data in the table to answer these questions.
1
Which object has the largest mass? ________________________
2
If you could stand on the surface of each object, predict on which one
you would weigh the most. Justify your prediction.
_____________________________________________________
Check your answers before proceeding.
6
Space science
Gill Sans Bold
You might remember that the closer you are to an object with mass, the
larger the gravitational pull is. That is why diameter is included in the
table above.
So what is gravity?
You have been using Newton’s theory of gravity. Newton said that
objects (which are things with mass) are attracted towards each other
by a gravitational pull (or gravitational force).
Complete these sentences about Newton’s theory.
1
The gravitational pull between two objects becomes
if the mass of either object gets larger.
__________________
2
The gravitational pull between two objects becomes
if the distance between the objects gets larger.
__________________
3
__________________
4
Gravity acts towards the centre of
5
Gravity and __________________ have very similar meanings.
causes objects to fall towards Earth and
gives them weight.
__________________.
Check your answers.
Newton’s theory about gravity is not the only one. The great twentieth
century physicist, Albert Einstein, also developed an explanation of
gravity.
Einstein’s theory – warped space
Einstein’s general theory of relativity had a totally different perspective
on what constitutes gravity. His view was that space curves, or warps,
due to the presence of matter. The bigger the mass, the more warped the
space around the mass becomes.
You can imagine this if you think of space as a flat, two dimensional
plane made of rubber. A massive ball stretches the rubber plane the same
way as its mass curves space. The amount of stretching depends on how
much mass the object has. The larger the mass, the more the rubber
plane stretches.
The spheres in the following diagrams represent objects of different
masses, m1, m2 and m3, that are causing a warp in space.
7
m
m32
m1
m
1
m
m23
1
Use the amount of warp that each mass causes to predict its mass.
Then list the masses (m1, m2 and m3) in order of increasing mass.
_____________________________________________________
Whether you think of gravity as a force or as a warp in space-time
doesn’t really matter for the purposes of this course, as long as you can
identify the relationship between mass and gravitational pull.
2
Write one or two sentences describing the relationship between mass
and gravitational pull.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
Isaac Newton correctly identified that gravity and gravitational pull could
be used to explain why the Moon stays in orbit around Earth. In fact,
gravitational pull keeps the planets orbiting the Sun too. And it all has to
do with falling!
8
Space science
Gill Sans Bold
Falling into orbit
Isaac Newton offered a thought experiment to explain how an object
could stay in orbit while falling towards Earth. It was from thought
experiments that he developed his explanation of the movement of
objects in the Solar System.
Falling around Earth
Newton imagined a cannon at the top of a tall mountain, firing
cannonballs.
cannonball
cannon
force from explosion
force due
to gravity
A cannon at the top of a high mountain.
Each cannonball experiences the force from the explosion and the force
of gravity. How would these two forces affect the movement of the
cannonball? What kind of path would it follow?
The combination of the two forces
would cause the cannonball to
travel in an arc.
9
Now imagine that the cannonballs
were fired with more and more energy
so that the forward force from the
explosions was larger and larger.
A
A cannonball with more energy would
travel in an arc and hit the ground a
long distance away (A).
If the cannonballs were given more
force by the explosion, they would hit
the ground farther and farther away
(B and C) from the cannon.
B
C
D
If the cannonball were fired with
enough energy it would fall entirely
around the Earth and return to its
starting point (D). This means that it
completes an orbit.
This is the same logic that is used for launching a spacecraft.
The spacecraft is fired into space at the particular speed and altitude
needed to make the craft’s falling path parallel to the curve of Earth.
Hence it keeps falling around Earth.
10
Space science
Gill Sans Bold
The Moon is falling
Newton stated that the Moon’s path is the result of it constantly falling
around Earth. This means that Earth’s gravitation is causing the Moon to
fall towards it. The reason why it doesn’t smash into Earth is that it is
also moving horizontally, so instead of falling straight down to Earth it
falls around in a circular path. This is its orbit.
Moon’s orbit
Moon
gravitational
pull
Earth
Notice in the diagram that Earth is also being pulled towards the Moon.
A gravitational pull occurs between Earth and the Moon because they both
have mass.
Why does the Moon orbit Earth? Using ideas from Newton’s cannonball
thought experiment to help you to write an explanation.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
11
Falling around the Sun
Just as Earth and the Moon are held together by a gravitational pull,
so too are the planets and their moons held in orbit around the Sun.
Jupiter
Mars
Venus
Sun
Earth
Mercury
Saturn
A view from Uranus of planets orbiting the Sun. Observations would show that
they revolve around the Sun at different rates.
If it were possible to view the planets from a position in outer space, you
would find that they orbit the Sun at different rates.
1
Which planet in the diagram is the largest distance (largest radius) from
the Sun? (This planet also has the orbit with the largest diameter.)
_____________________________________________________
2
Which planet in the diagram would you expect to experience the
most gravitational pull from the Sun? Why?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
12
Space science
Gill Sans Bold
The table below shows the speed of orbit in kilometres per second (km/s)
for each of the planets. Note the relationship between the distance from
the Sun and a planet’s speed in orbit.
The distance from the Sun and orbiting speeds of planets
Planet
Distance from Sun
(millions of km)
Speed in orbit
(km/s)
58
48
Venus
108
35
Earth
150
30
Mars
228
24
Jupiter
750
13
Saturn
1 430
9.6
Uranus
2 870
6.8
Neptune
4 490
5.4
Pluto
4 910
4.7
Mercury
3
Describe the trend in the speed of the planets as they are further
from the Sun.
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
13
Artificial satellites are falling too
A satellite is an object in orbit around another object. For example,
the Moon is a natural satellite of Earth. Earth has other satellites, called
artificial satellites, which are pieces of equipment that humans have
placed into orbit.
The speed of an orbiting object is crucial if it is to remain in orbit:
•
too slow and it will spiral back to Earth
•
too fast and it will spiral away from Earth, off into space.
Spy satellites are close to Earth (about 100 km up) and travel at speeds
of about 29 000 km/hr. Telecommunications satellites (situated about
36 000 km up) travel at speeds of 11 000 km/hr.
Look at the satellite in the diagram then
answer the questions below. The diagram
is not drawn to scale.
What would have to happen to the speed of
orbit of the satellite if it were moved to
position P and still made to orbit Earth?
Q
P
____________________________________
____________________________________
____________________________________
____________________________________
Check your answers.
Then complete Exercise 2.1.
14
Space science
Gill Sans Bold
Environments of negligible gravity
Weightlessness is a term used to describe a situation where an object or
person experiences nearly no gravity.
Astronauts, their space shuttles and space stations in space experience
weightlessness.
Astronauts experience weightlessness as they fall in an orbit around Earth.
The diagram above shows such a situation.
15
Developing the idea of
weightlessness
Scientists knew about weightlessness long before the first people shot out
into space. How did this idea develop?
Newton again
Newton did more than think up thought experiments about gravity!
He also studied forces that cause movement and deduced laws of motion.
Newton’s third law of motion states that every force has an equal and
opposite force. He explained that because an object has weight and
pushes down onto a surface, the surface is also pushing back up with an
equal and opposite force.
weight of apple
pushes down on
to his hand
Isaac’s weight
pushes onto
the floor
hand pushes up to
oppose the force
of the apple down
the floor pushes
up on Isaac
Newton’s third law: for every force, there is an equal but opposing force.
The feeling of weight exists for as long as the two forces are acting on an
object at the same time but in opposite directions.
16
Space science
Gill Sans Bold
Isaac Newton explained that weightlessness could be achieved whenever
the opposing force is removed. In other words, weightlessness occurs
whenever an object is falling.
Remember how Galileo demonstrated that all objects fall at the same
rate? This is what is happening to Newton and his apple.
Experiencing weightlessness conditions!
When the floor is removed, Isaac and the apple are in a state of free fall
and so are weightless. You may have experienced this feeling inside an
elevator when it begins to go down. You can feel it in an aeroplane
beginning to descend or when it hits turbulence and falls rapidly.
Perhaps you have been over a bump in the road or on a roller coaster and
felt like you are floating (or at least your stomach feels like that!).
A person would experience a feeling of weightlessness when falling
towards Earth. A free fall ‘ride’ at a fun park is as close as most people
come to experience weightlessness.
It is not strictly correct to use the term weightlessness because an object in
free fall still has weight, causing it to fall.
You can demonstrate weightless conditions in the following activity.
Weightless water activity
You will need: a disposable foam cup.
Directions:
1
Fill a disposable foam cup with water.
Then puncture the side of the cup,
near the bottom, with a pencil.
What happens?
hole
Did you observe the water pouring out?
This is due to Earth’s gravitational pull
on the water.
water coming out
17
2
Now refill the cup, making sure your finger covers the hole.
finger placed over
hole to stop water
from coming out
3
Carefully stand on a chair outside where spilled water cannot cause
a problem. Release the foam cup from your grip so that it falls
straight to the ground.
What do you observe?
Did you observe that the water remained in the cup as it fell?
The cup and its water are both weightless as they fall. They are just
as weightless as the space shuttle and astronaut out in space.
4
Explain why a falling object experiences weightlessness.
_____________________________________________________
_____________________________________________________
_____________________________________________________
5
Why is the term weightlessness misleading?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
18
Space science
Gill Sans Bold
Experiencing weightlessness
In the previous section, you read about some examples of situations
where you may experience weightless conditions. (Look back at the
information in ‘Newton again’ if you can’t think of any examples!)
These weightless situations usually only last for a part of a second.
When scientists first began preparing for space travel, they had to find
better ways to predict how weightlessness would affect astronauts.
You would probably laugh if you saw these early astronauts training!
Sometimes they trained in water because of the floating feeling that
water gives. Sometimes they dangled from ropes to see how difficult it
was to perform tasks. Better ways to simulate weightlessness
were needed.
Simulating weightless conditions on Earth
Before going into space, astronauts are trained in a weightless environment
on Earth. The equipment needed is called a zero-g simulator. Zero-g
means no gravity (there still is gravity but it is not apparent). A simulator
is essentially just an aeroplane flying in a curved path so that it falls for
long enough for passengers to experience some time of weightlessness.
upthrust force
circu
lar p
a
th
th
pa
r
la
cu
cir
weight force
19
You can watch a video about a commercial adventure that enables you to
experience weightlessness. You will find an access link at:
http://www.lmpc.edu.au/Science
20
Space science
Gill Sans Bold
Animals in space
Testing weightless conditions
Although moments of weightlessness can be experienced on Earth,
scientists were concerned about the unknown effects on the human body.
They were also concerned about how human astronauts would respond to
take-off and re-entry. So to test the effects of these things on living
organisms, both Russian and American animals were launched into space
before any humans.
Many animals have travelled in space. In the 1950s and 1960s, the
Russians sent dogs and the Americans sent monkeys into space in some
of the first craft to orbit Earth. Today, animals and insects are still
launched into space as part of the space program.
Dogs in space
The first animal sent into space was the Russian dog Laika – a mixed
breed or a Husky variety. She was launched on 3 November 1957 aboard
the satellite Sputnik 2. This 508 kg satellite was the second artificial
object to orbit Earth.
Sputnik 2 was not designed for recovery and Laika died in orbit.
She lived for seven days in space until her oxygen supply was exhausted.
Her vital signs were monitored by sensors and transmitted to Earth via
telemetry signals.
This launch showed that living animals could survive in outer space and
sped up the race between the US and the Soviet Union to send humans
into orbit around Earth.
Sputnik 9 was launched on 9 March 1961 and carried the dog
Chernushka (Blackie) on a one orbit mission. Also on board the
spacecraft was a dummy cosmonaut, mice and a guinea pig. The flight
was successful and helped pave the way to Yuri Gagarin’s flight the
21
following month. Yuri Gagarin was the first human ever to be sent
into space.
Space monkeys
On 13 December 1958, the US Army launched a squirrel monkey named
Gordo aboard a Jupiter AM-13 booster. Gordo made the flight with no
adverse effects but could not be recovered because the flotation
mechanism of the rocket’s nose cone failed.
On 28 May 1959, the USA launched two monkeys named Able and
Baker. The two female monkeys were instrumented with electrodes to
monitor their vital signs during the flight. They survived the flight into
space and were recovered.
The US launched a chimpanzee named Ham on 31 January 1961.
During this flight Ham experienced about seven minutes of
weightlessness. He performed some simple tasks such as pulling a righthand lever when a white light came on and a left-hand lever when a blue
light came on. Medical sensors were attached to Ham to monitor his
vital signs.
Ham’s rocket experienced a number of problems. As a result, he
travelled 122 miles further down range than planned and experienced a
re-entry deceleration of almost 15 G. His spacecraft splashed down in
the ocean and was successfully recovered. Afterwards, Ham was in good
spirits and posed for pictures with the sailors on the recovery ship.
Find information about space missions using animals.
Identify reasons why animals have been sent into space before humans.
There are some sites to get you started at: http://www.lmpc.edu.au/Science
Once you have selected the information you need, answer the following
question. Your answer here is a draft for the question in the exercises.
Discuss why animals were sent into space before humans.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Now complete Exercise 2.2.
22
Space science
Gill Sans Bold
Suggested answers
…and gravity causes weight
1
the Sun
2
You’d weigh the most on the Sun because it has the most mass so
the gravitational attraction between you and the Sun would be the
greatest.
So what is gravity?
1
larger or bigger or stronger
2
less or smaller or weaker
3
gravity
4
Earth
5
gravitation
Einstein’s theory – warped space
1
m2 , m3 , m1
2
An object (with mass) experiences a force (gravitational pull) from
another object with mass. The force is most significant when the
two objects are close together. The larger the masses of the objects,
the greater the gravitational pull.
The Moon is falling
The Moon is always falling towards Earth because of the gravitational
pull between Earth and the Moon. However, the Moon is also
moving forwards. These two movements keep it travelling in a path
around Earth.
23
Falling around the Sun
1
Saturn
2
Mercury experiences the most gravitational pull because it is closest
to the Sun. (From this diagram, you could also argue that Jupiter
could experience the most gravitational pull because it is the planet
with most mass. However, the distances between planets are much
larger than is shown in the diagram, and the effect of distance on
gravitation is much larger than the effect of mass of one planet.)
3
As distance from the Sun increases, the speed of the planet
decreases.
Artificial satellites are falling too
It would have to move faster to stay about the same distance from the
Earth (because it would have moved closer to Earth and the gravitational
pull would be stronger).
Weightless water activity
24
4
An object experiences weightless conditions when it is falling
because it is being acted on by a downwards force due to Earth’s
gravitational pull but there is no upwards force to stop the object
from moving.
5
The term ‘weightless’ is misleading because weight causes the
object to fall.
Space science
Gill Sans Bold
Exercises 2.1 and 2.2
Name: _________________________________
Exercise 2.1
a)
What is the relationship between mass and gravitational pull?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
b) Why does the Moon revolve around Earth?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
25
Exercise 2.2
a)
List three situations on Earth where you could experience
weightlessness.
•
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
•
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
•
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
b) Discuss why animals were sent into space before humans.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
26
Space science
Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
Part 3: Living in space
2
0
0
I
2
r
be S
o
t
c NT
O
ng DM E
i
t
ra E N
o
rp A M
o
nc
Contents
Introduction................................................................................ 2
Stuffing your face in space ........................................................ 4
Ingestion and gravity ............................................................................5
Fluids in space......................................................................................6
Food for space flights .............................................................. 10
Selecting and storing foodstuffs for space ....................................... 10
Maintaining bone and muscle health ....................................... 13
The need to exercise......................................................................... 14
Bone health........................................................................................ 16
Body rhythms in space ............................................................ 17
Exercises – Part 3 ................................................................... 27
1
Introduction
Whenever you think about living in a weightless environment it is always
with a sense of novelty and excitement. You would hardly consider the
impacts that a prolonged term of weightlessness would have on your
body functions.
This part of the module explores the problems associated with selecting,
storing and ingesting food and water in space. You will select a variety of
foodstuffs from the actual NASA space shuttle menu and look at the way
these foods are stored.
Maintaining your muscle tone and bone density is a challenge because
these deteriorate in a prolonged weightlessness environment. You will
devise a series of exercises for all the major muscle groups and collect
information about how this kind of activity is performed in space.
Have you ever suffered from jet lag? Or do you know anyone who has
been on shift work? Disruption to your sleep patterns can affect the
normal functioning of the body. How is this managed in space, where
there is no normal night and day?
In this part of the module you will learn about ways these challenges are
overcome in space.
You will need to collect the following equipment for activities within
this part: a smooth stick such as a broom handle, a strip of rubber that can
be made into a ring (such as the inner tube of an old bicycle tyre) and a
medical thermometer.
2
Space science
•
define ‘ingestion’ and explain how ingestion occurs without the
assistance of gravity
•
discuss the problems associated with drinking fluids while in an
environment of negligible gravity
•
describe possible containers through which food may be accessed so
as to reduce spillage
•
describe the forms in which food and drinks could be transported and
stored for use by space personnel over their time in space
•
account for the role of gravity in the maintenance of bone health
•
account for the role of gravity in maintenance of muscle tone
•
identify some human circadian rhythms and discuss effects of
disruption to these
•
describe ways in which normal circadian rhythms can be maintained
during space travel.
•
gather information from first-hand and secondary sources and use
available evidence to devise a series of exercises for all major muscle
groups of the body that could be performed within the confines of a
spacecraft
•
gather from secondary sources information to identify activities that
disrupt circadian rhythms
Extracts from Senior Science Stage 6 Syllabus © Board of Studies NSW, October
2002. The most up-to-date version is to be found at:
3
Stuffing your face in space
Astronauts are human beings – a type of animal from Earth. They need to
take in nutrients and water to stay alive. This is called ingestion, which is
defined as the act of taking up substances into the body. Food and water
are included in this definition.
Catering to the food needs of astronauts is important especially as
space missions last even longer. The average length of a space shuttle
flight is ten days. Space station astronauts have stayed in space for
months. Valeriy Polyakov was on Mir for 438 days. Not only is there no
gravity but there are no supermarkets to go and buy the bread and milk!
Try making some predictions about ingestion in space:
If you were an astronaut living on a space station, what would be some of
the problems that you would encounter when it comes to dinnertime?
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Come back to this question once you have finished Part 3. You should be
able to add more problems to the list you have begun above.
4
Space science
Ingestion and gravity
After you swallow a mouthful of food or drink, does it need gravity to
push it the rest of the way down your body? If you eat a banana or piece
of bread while you are upside down, does the food go up or down? If you
are not too sure, go ahead and try the following activity.
Stand on your head or hang upside down by wrapping your legs over a bar
or something. (You can sit on a chair or lie on a bed and lean over so that
your head is near the floor.) Take a bite of a banana or piece of bread, chew
then swallow.
•
What happens to the food? _______________________________
•
What about food already inside your body? Does it fall out?
_____________________________________________________
Of course the food doesn’t fall out! The food moves down into your
stomach and stays there. Eating food while standing on your head is
possible because the food is assisted in its movement to the stomach by the
muscular contractions of the oesophagus.
When food is swallowed,
muscular action (called peristalsis)
pushes food through your
digestive system
Swallowing is a muscular action that does not depend upon gravity. The arrows
show the position of food through the digestive system.
What is ingestion and why is gravity not needed for it to occur?
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
5
Eating in space isn’t difficult once you’ve got the food into your mouth.
The problem is, a space station or space shuttle is constantly falling in
orbit around Earth so the astronauts and everything else inside, including
foods, are ‘weightless’. Weightless conditions cause great difficulties for
preparing food and drink and transferring them to your mouth.
Drinking fluids in space needs particular care.
Fluids in space
What does a falling water drop look like?
The traditional way of representing a falling water drop is not the real
shape of the drop. A water drop may be tear-shaped when it is just about
to fall away from the tap but still connected to it.
If you were able to witness the free fall of a weightless water drop in slow
motion, then you would see it as a tiny sphere. This is because water
particles attract each other and create a sphere shape.
The real shape of a drop of water.
If the lid of a container of fluid is removed in space, the fluid will form a
floating sphere. This is because of the attraction of the water molecules
for each other in an environment of negligible gravity.
6
Space science
Problems in drinking fluids
If you try drinking from a glass while you are weightless in a spacecraft,
you will get very frustrated because nothing will pour. Tipping the glass
to your mouth, as you would on Earth, will not bring any fluid to your
mouth. Obviously, it would have also been impossible to pour a liquid
into the cup to begin with!
Try this simple activity to demonstrate what it would be like to pour a liquid
out of a glass in an environment of negligible gravity.
1
Hold up an empty glass. Think of the air inside of it. Imagine that you
are in space and that the air in the glass is really floating water.
2
Now tip the glass to pour out the ‘water’. What would happen to the
‘water’ in the glass?
_____________________________________________________
_____________________________________________________
_____________________________________________________
Could you see that turning the glass made no difference to the air inside it?
The air didn’t pour out; it just kept floating where it was. In a similar way,
can you picture how turning the glass of water in space would not pour out
any water?
Astronauts have a drinking problem!
The problems for drinking in space are:
•
being able to get the fluid from the container to the mouth
•
preventing the continual loss of the fluid from the container after each
suck on the straw.
What sort of drink container do you think would solve these problems?
Describe it.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
You’ll be able to see how good your idea is by considering the kinds of
containers that really are used in space.
7
How does an astronaut drink?
To help with drinking while in space, aluminium pouches and lockable
straws are used. For drinks, the astronaut has a selection from plain water
or powdered (dehydrated) tea, coffee, cocoa and a variety of fruit-flavoured
drinks.
The powdered drink is rehydrated with hot or cold water from the water
dispenser in the galley (the spacecraft’s kitchen), then a plastic drinking
straw is inserted into the top. A closable clamp on the straw prevents
liquid from escaping when the astronaut is not drinking (between sips).
1
Explain how problems of drinking in an environment of negligible
gravity are overcome.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
2
What kind of problems do you think astronauts would have if bits of
food or drink escaped from a food container?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
3
Recommend the best kind of food container to prevent spillage from
occurring in space.
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers before proceeding.
Can astronauts run out of drinking water?
Most food and drink consumed on spacecraft is stored in a dehydrated
form. This takes up less space and helps the food to keep. But where does
the water come from for drinking and rehydrating food?
8
Space science
The supply of fresh water on a craft such as the space shuttle is never a
problem. Water is constantly being made as a by-product of burning in the
fuel cells. Fuel cells produce electricity by combining hydrogen and
oxygen (which forms water).
However, the International Space Station ISS (and in the future, a space
base on the Moon or a planet) does not possess fuel cells for making
electricity but takes advantage of solar arrays. Consequently, the continual
supply of water on the space station must be ensured or astronauts could
run out of water. The Russian supply craft carry water as well as food to
the Space Station. Rationing and recycling of water are essential to avoid
having to supply five tonne of water per year per crew member. Water is
distilled from the crew’s breath, urine, mouthwashes and handwashing.
9
Food for space flights
What sort of food do astronauts eat? You have already thought about
some of the issues of suitable food containers and spillages. In this
section, you’ll learn more about containers used for storing foods, what the
foods are and how they are preserved for a long space flight.
Read through the following information about space food used on a NASA
space mission. Highlight important ideas as you go. You will need to use
information from this section to complete the first exercise for Part 3.
Selecting and storing foodstuffs for
space
When NASA scientists are selecting the kinds of food and drink to be
transported and stored for use on a space mission, they need to consider a
number of things. These include:
10
•
preventing spillage in weightless conditions
Any food or drink that escapes from its container while being eaten in
space may cause great danger to the spacecraft if it floats into
equipment or instrumentation. Short circuits could mean a major
equipment failure and cause the crew to not be able to return from
space. Problems can also occur if the escaped ‘floaters’ are inhaled.
Consequently, all food and drink is prepared and stored in containers
that will prevent spillage.
•
preventing crumbs from forming
For example, tortillas (mexican corn bread) are preferred to bread
because they make fewer crumbs. Sandwiches can be eaten early in
the mission when they are fresh and less likely to form crumbs.
•
preventing food from floating away
Foods are generally made with a sauce or gravy to hold pieces
together. Any food that does escape will stay stuck together as a
large drop.
Space science
•
reducing weight for a successful launch
Weight and volume of food and drink are always a concern for any
mission since the total weight of the spacecraft must be kept at a
minimum for a successful launch. For a typical 10 day space shuttle
mission, only 1.7 kg of food is taken on board for each astronaut.
To reduce weight and ensure good storage, much of the food is in a
dehydrated form. Water produced by the space shuttle fuel cells is
used to hydrate the dehydrated food.
Types of food packaging
Until 1991, a lot of food was packaged in rigid, square containers.
These containers caused problems due to the large amount of
rubbish created.
Consequently, they were replaced by flexible, plastic packets, which have
a valve for inserting water to rehydrate the food inside. These are also
much easier to pack down in the rubbish compactor. They are made from
a microwavable material so that they can be easily heated. The top of the
container can be cut with a pair of scissors so that the contents can be eaten
with a fork or spoon.
Some other foods may be stored in pull-top cans or foil pouches, such as
sweet and sour beef shown in the photo below.
The beverage (tea, coffee and cocoa) packages for use on the space shuttle
and the International Space Station are made from foil and a plastic to
provide longer shelf life (so that they keep for more time).
Each astronaut’s chosen food is colour coded on the package with a Velcro
spot. The colours enable the astronauts to recognise their daily menu and
the Velcro lets them attach a food package to their clothing to prevent it
from floating away.
Types of space food
Space food can be preserved or stored in a variety of ways, including:
•
rehydratable food
This is food that water has been removed from by freeze drying;
for example, beverages and hot cereal.
•
thermostabilised food
This food has been heat processed and canned in aluminium cans to
destroy bacteria and fungi, allowing the food to be stored at room
temperature; for example, pudding, fruit and tuna in cans.
•
intermediate moisture food
Some water has been taken out of the food to maintain the soft texture
11
and reduce the potential for growth of bacteria and fungi. As a result,
the food can be directly eaten without the need for preparation; for
example, dried fruit.
12
•
natural form food
This food is stored in a flexible pouch and is ready to eat; for example,
nuts, biscuits and health bars.
•
irradiated food
So far, beef steak and smoked turkey are the only foods sterilised by
ionising radiation, which allows them to be kept at room temperature.
•
fresh food
This food is not preserved or processed and is generally best eaten
early in the mission; for example, apples and bananas.
Space science
Maintaining bone and
muscle health
Everything about living in a weightless environment is different from
being on Earth.
For example, astronauts’ legs and pelvic regions no longer support their
insides and their organs respond as though gravity were not present.
Their organs tend to ‘float’ up inside their bodies.
Blood in the body is no longer being pulled down to the astronauts’ legs by
gravity as it is on Earth. The blood ‘floats’ and so distributes evenly
throughout the body, giving astronauts much fuller, rounder faces than
back on Earth.
These changes may not affect astronauts very much. But other changes
can be very important. For example, a natural and unfortunate
consequence of being in space is the deterioration of the body’s muscles
and bones.
Being weightless means that many of the astronauts’ muscles are not being
used. Their muscles begin to waste away, particularly muscles of the legs
and lower back.
Describe how your muscles feel after being sick in bed for several days.
_________________________________________________________
_________________________________________________________
Check your answer before you continue.
Muscle and bone problems are insignificant in a short duration shuttle
mission but are of great concern for long stays in space, such as on a space
station or eventually, for a trip to Mars. Sore muscles may be the end
result of a space shuttle mission but there is a serious threat to an
astronaut’s health from long duration space travel.
13
The need to exercise
The decrease in size and strength of muscles is called muscle atrophy.
On Earth where the human body evolved, the stress of resisting the pull of
gravity, in activities such as walking and running, enables muscles and
bones to remain in top condition.
Cardiovascular fitness
While in space, the heart does not need to work as hard to pump blood
around the body. This becomes a problem because heart muscles gain
their strength from regular periods of hard work. When you exercise, you
make your heart pump harder; therefore you are helping it to build up its
muscles. This is called cardiovascular fitness.
1
Why do you think a bicycle ergometer is suitable for exercise in space?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answer.
Astronauts must exercise regularly to maintain cardiovascular fitness.
This may be done on a treadmill or a bicycle ergometer, as well as using
bungee rubber bands for light resistance exercise.
A well-conditioned cardiovascular system will minimise the potential for
fainting on re-entry or landing.
2
Why could an astronaut faint on re-entry or landing?
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answer.
14
Space science
Here is an activity to investigate exercises for all the muscle groups in the
body, which could be done in the confined space of a spacecraft.
Constructing simple exercise equipment
The condition of the cardiovascular system is improved when your pulse
rate is increased with exercise.
Can a broom handle and an old piece of rubber, such as the inner tube of
bicycle tyre, assist in increasing pulse rate while in space? Find out by
performing the following activity.
Instructions:
1
Rest for a couple of minutes then find your pulse. Count the number
of beats in one minute. Record your measurement in the table
provided.
2
Arm exercise
Hold onto two places of the rubber tube; stretch and release.
Repeat for one minute. Measure and record your heart rate.
3
Leg exercise
Loop the rubber tube around the broom handle and tighten. Place one
foot onto the bottom of the rubber exercise loop. Hold the broom
handle with both hands as you try to stretch the rubber loop with the
muscle strength of your leg. Repeat this action for one minute.
Measure and record your heart rate.
Results:
Activity
Heart rate
(beats per minute)
after resting
after arm exercises
after leg exercises
4
a) Was the exercise successful in raising your pulse? _________
b) Would it assist you to maintain cardiovascular fitness? Explain.
__________________________________________________
__________________________________________________
15
5
Why is this kind of exercise suitable for astronauts? Give at least
three reasons.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Please read the comments in the suggested answers.
Bone health
Bones lose calcium in space. (Bones also lose calcium with age. It is
something you need to keep in mind as you get older. Including dairy or
other calcium rich products in your diet is important, especially during
teen and early twenty years when bone density reaches its highest levels.)
Most of the calcium loss is thought to occur in the leg bones and spine.
These are responsible for erect posture and locomotion.
Scientists have determined that weight-bearing exercise maintains bone
density. On Earth, regular walking (and a healthy, calcium-rich diet) is
sufficient to keep high calcium levels in bones. However, there is not far
to walk in a spacecraft and the weightless conditions mean that bones do
not carry much weight during exercise anyway.
Astronauts can lose significant amounts of bone density, especially on
long missions. What happens when bones lose calcium? Can you
remember the activity in the Medical technology – bionics module where
you left a cleaned chicken bone soaking in vinegar? Recall how the bone
became softer and more flexible from the loss of calcium.
Complete Exercises 3.1 and 3.2.
16
Space science
Body rhythms in space
Have you ever noticed that you don’t need to look at the clock to tell you
that it is time for lunch or dinner? Animals, including humans, have
built-in body clocks that produce daily patterns in body processes called
circadian rhythms.
What are circadian rhythms?
Many of your body functions run on a 24 hour cycle circadian rhythm.
Daily rhythms affect:
•
body temperature
•
blood pressure
•
manufacture of urine
•
sleep.
Scientists believe that the master clock for circadian rhythms is in a part of
the brain that is influenced by light cues. As light fades, the cells in the
retina (the light-sensitive lining of the eye) pass messages directly to a
cluster of cells inside the hypothalamus (at the bottom of the brain).
This information is used to synchronise your circadian rhythms with the
amount of sunlight. With decreasing sunlight, this part of the brain
produces a hormone that causes a drop in body temperature, and sleepiness.
Your nervous, urinary, endocrine, respiratory and cardiovascular systems
are coordinated by the circadian timing system. Circadian rhythms affect
all ways that your body works – physiology, biochemistry and behaviour.
If your daily clock is not functioning properly then you may experience
headaches, irritability, gastric discomfort, chills, light-headedness,
difficulty in concentrating, lowered task performance and sleep problems.
For example, if you have travelled long distances on a plane, you may
have experienced some of these symptoms, as jet lag. Jet lag is caused by
a disturbance of your body's daily clock.
17
Here is an activity that lets you observe one (or more) of your circadian
rhythms.
Observing changes in body temperature
Body temperature is directly controlled by your circadian rhythms.
What happens to the temperature of the body as time progresses and the
amount of sunlight changes?
1
Use a medical thermometer to monitor your body temperature for
several days, making sure that you take your temperature at the same
times every day. These times are suitable: 7 am, 11 am, 4 pm, 7 pm
and 10 pm.
Note: The temperature may only vary by 0.1°C. Do not expect big
variations (unless you are sick and then you are not observing your
circadian rhythms.)
Body temperatures throughout the day
Day/Date
18
Time
Temperature
(°C)
Space science
2
Average your readings for the same time each day. Draw up a table in
the space below to show the times and your average temperatures.
3
Plot your data onto the graph grid below, with the:
•
vertical axis representing your body temperature
•
horizontal axis representing the times you took your temperature
•
points marked with crosses and connected to make a line graph
(Do not draw a column graph.)
•
title of your graph.
19
Use information from your investigation to compete the tasks below.
4
What has your data revealed about your average body temperature from
the first morning period to the last evening period?
_____________________________________________________
_____________________________________________________
_____________________________________________________
5
Imagine that you worked shift work, where you slept during the day
and worked during the night. Predict how your body temperature
cycle could affect your sleep and work.
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
Sleep rhythms
Your circadian clock tells you when it is time to go to sleep and when it is
time to wake. So, disruption to circadian rhythms by changing the cues of
light and dark can easily disturb sleep.
A person’s health, ability to perform tasks and ability to learn new things
is greatly affected in a negative way if the circadian timing system is not
operating efficiently. For example, people may fall asleep at the wrong
time, making many activities, such as driving, dangerous because people
are required to be very alert.
Problems of night shift work are also directly related to the circadian
timing system. Surveys of industrial accidents have shown that many
serious problems and accidents occur during night shift work, particularly
around midnight.
Are you taking notice of your circadian timing system for sleep? If you
want to perform your best in the HSC, you need to get enough sleep and
avoid wasting time in trying to study at times when your mind and body
are least able to learn and perform.
20
Space science
Here is a simple activity to test whether you are following the cues from
your circadian rhythms.
1
First, before you do the test, answer this question.
Do you think that you get enough sleep? Explain.
_____________________________________________________
_____________________________________________________
2
Do you tend to drop off to sleep when you don’t really mean to?
This is called ‘dozing off’.
Here is a rating scale to describe how often you doze off. It is based
on the Epworth Sleepiness Scale.
never
= 0
sometimes
= 1
often
= 2
very often
= 3
Use this scale to rate how often you doze off during the activities
listed in the table below.
Activity
Dozing off rating
sitting and reading
sitting and talking
sitting in a movie theatre
sitting watching TV
sitting in a moving car as a passenger
lying on your bed resting or reading
TOTAL
3
Compare your total with the scores below.
0 to 5
You are getting enough quality sleep.
6 to 8
This is a common result but you have a mild lack of sleep.
9 or more
You are significantly deprived of quality sleep.
21
4
Does your result in Question 3 agree with your answer in Question 1?
Do you think that you have a sleep problem? Explain.
______________________________________________________
______________________________________________________
How does a disrupted circadian rhythm for sleep affect you? For example,
can you remember a time when you were really tired? Perhaps you’d
stayed up very late. Do you think you were more likely to make mistakes?
5
Describe how disrupting your circadian sleep pattern affected you.
______________________________________________________
______________________________________________________
______________________________________________________
Remember that you will not learn and perform tasks as effectively if you
do not allow your circadian timing system to work for you. If you can,
go to bed as soon as you feel tired at night. Try to go to sleep at a similar
time each night.
Reaction times
If you have time, here is an activity to help you to see how disrupting your
sleep rhythms affects what you can do. You will compare your reaction
times during early morning with those late at night when you are tired.
You will need to do this experiment at least twice. (The table following
gives spaces for you to record results for two separate days.) You need to
at least try the experiment when you feel wide awake and alert in the
morning and again at night when you are very tired.
22
1
Have someone hold a ruler vertically with the zero mark at the bottom,
between the thumb and forefinger of one of your hands.
2
Position your thumb and forefinger around the ruler, without touching
it, near your partner's fingers.
3
Your partner should release the ruler without giving warning to you.
You must catch the ruler by placing your fingers onto the falling ruler
as soon as you can.
4
Record the mark where your fingers are (the distance in centimetres
that the ruler fell before you caught it). Repeat the activity four times
and calculate an average result.
Space science
Table of results for reaction time trials
Trial
When you are alert
When you are tired
Day 1
Day 1
Day 2
Day 2
1
2
3
4
5
AVERAGE
5
How do your average reaction times compare when you are alert
and when you are tired?
_____________________________________________________
_____________________________________________________
_____________________________________________________
6
How do you think your ability to do things could be affected by
being tired? Give some examples.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Please read the comments in the suggested answers.
23
Space travel and circadian rhythms
The space shuttle orbits Earth in only 90 minutes, producing brilliant
daylight every 45 minutes and extreme darkness every other 45 minutes.
(Think about what that would feel like!)
Since there is no normal day or night, the disruption of the sleep/wake
cycle of an astronaut can negatively affect alertness and performance.
The astronaut may feel very exhausted and have poor reaction times. As a
result, the astronaut may become sleepy and have poor responses at the
wrong time, such as during a space walk. Not being able to react instantly
in times of danger may risk his/her life and possibly the lives of the whole
crew.
Some strategies for maintaining circadian rhythms in space
In the days leading up to a mission, astronauts sleep in rooms that do not
have windows. Throughout their sleep period, the lights in the room are
switched on automatically every 90 minutes for a period of 45 minutes.
It is hoped that this kind of exercise will help acclimatise the astronauts for
their time in space.
While in space:
•
all the astronauts sleep at the same time
•
a 24 hour timetable is organised on board the space shuttle, with
regards to being awake and being asleep, in a similar way to being on
Earth. Mission control wakes the astronauts 8 hours after bedtime
•
the lights in the orbiter are turned off during the sleep period
•
shades are placed on all windows to reduce the entry of light
•
the astronauts can wear eye masks to further prevent the rapidly
changing ‘day’ and ‘night’ from disturbing their circadian rhythms
and therefore their sleep pattern
•
astronauts may also use their clothing to keep track of what day it
would be on Earth and also organise their awake time.
Despite precautions taken, astronauts still suffer disruption to their
circadian rhythms, which must be seriously addressed if long distance
space travel (for example, to Mars) is to be undertaken.
Now use information from the preceding pages to complete Exercise 3.3.
24
Space science
Suggested answers
Ingestion and gravity
Ingestion means taking substances into the body. Gravity is not needed for
it to occur because the digestive system has a muscular action to move
food through the body.
How does an astronaut drink?
1
The container is sealed so that the drink cannot escape. It has a ‘plug’
to stop liquid from leaking from the bottle when the astronaut is not
drinking. Bottle concertina (folds up) so that the astronaut can easily
squeeze the drink out of the bottle and into his/her mouth.
2
Escaped bits of food or drink would float about the spacecraft. (Look
at the crumbs and mess around your dinner table if you’d like some
idea of the risk!) Bits of food could get into instruments and
equipment and cause damage. They could be inhaled by an astronaut,
causing choking, or go into someone’s eye.
3
The container should be strong. It should remain sealed as much as
possible. For example, it could be squeezable with a firm-fitting cap.
Maintaining bone and muscle health
Have you noticed that you feel weak? It can be an effort even to stand up
and taking a shower may be quite tiring.
Cardiovascular fitness
1
The activity:
•
lets the astronaut exercise vigorously, so that the heart and
muscles can work hard (especially the leg and lower back muscles
which are the muscles which need exercise in space)
•
does not take up much space
25
•
2
does not involve weight; instead, the astronaut pulls and pushes
against the machine
• can be measured and monitored using instruments.
A person faints when insufficient blood reaches the brain. When the
astronaut approaches Earth, gravity will pull the blood downwards and
away from the brain. The heart will have to work harder to give the
brain a sufficient blood supply, so a strong heart is needed.
Otherwise, the astronaut would faint.
Constructing simple exercise equipment
4
b) Any exercise that increases the heart rate will assist in
maintaining cardiovascular fitness. This is because the heart
remains fit by doing periods of hard work and that means beating
quickly and strongly.
5
The exercises you have been doing are suitable for an astronaut
because they:
• let the astronaut exercise vigorously, so that the heart and muscles
can work hard (the arm and leg exercises described can also
exercise back, chest and abdominal muscles).
•
•
•
do not take much space to perform
do not involve weight; instead, the astronaut pulls and pushes
against the equipment
do not use bulky or heavy equipment.
Observing changes in body temperature
4
5
Your body temperature is slightly lower when you first wake up so if
you were still in bed at 7 am you may have noticed this. Throughout
the day, your temperature should remain constant. At night, especially
when you are very tired, your temperature will drop slightly.
During the day your temperature would be higher, which might make
it harder for you to sleep. During the night, when you are working,
your temperature could be lower, making you feel cold and making it
harder to concentrate on what you are doing.
Reaction times
5
6
26
Reaction time is longer (the ruler falls further) when you are tired.
Anything that needs you to act quickly would be affected; for
example, driving, responding to danger and even operating a machine.
You may also realise that it is harder to ‘think straight’ when you are
tired and that solving problems is harder. For example, studying is not
very productive when you are tired. It is not a good time to try to sort
out important issues or relationships either.
Space science
Name: _________________________________
Exercise 3.1
a)
In what way is gravity important for maintaining bone health?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
b) In what way is gravity important for maintaining muscle tone?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
27
Exercise 3.2
c)
You have performed your own exercise activity using a stick and
rubber loop to learn about ways of maintaining muscle tone and
cardiovascular fitness in space. You should also look at web site links
from http://www.lmpc.edu.au/Science
Using information and ideas from these, devise your own series of
exercises for all major muscle groups of the body that could be
performed within the confines of a spacecraft. Make sure your
exercises involve arm, leg, chest, abdominal and back muscles.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
28
Space science
Exercise 3.3
Look back through the information, activities and web site links from
http://www.lmpc.edu.au/Science about activities that disrupt circadian
rhythms. Then complete the tasks below.
a)
List at least three examples of body processes controlled by
circadian rhythms.
•
__________________________________________________
•
__________________________________________________
•
__________________________________________________
•
__________________________________________________
b) List at least two activities that could disrupt circadian rhythms.
c)
•
__________________________________________________
•
__________________________________________________
•
__________________________________________________
Discuss the effects of disrupting circadian rhythms.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
d) Describe ways in which normal circadian rhythms can be maintained
during space travel.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
29
Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
Part 4: Rockets and shuttles
0
20
I
er
b
to T S
c
O EN
g
in D M
t
a
r EN
o
p
or AM
c
n
2
Gill Sans Bold
Contents
Introduction ............................................................................... 2
Going up.................................................................................... 3
What are rockets? ................................................................................3
Rocket stages.......................................................................................6
The space shuttle ...................................................................... 8
Parts of the space shuttle ....................................................................8
Launching the space shuttle ..............................................................11
Experiencing lift-off and re-entry........................................................11
Materials used in the space shuttle ...................................................15
Advantages and disadvantages of the space shuttle program ........17
The changing nature of space flights....................................... 19
Changes up to the present ................................................................19
Changes into the future......................................................................21
Exercises – Part 4 ................................................................... 29
1
Introduction
Just think about the amount of effort and energy needed to get rockets
and shuttles up into space. A large booster rocket is required to launch a
spacecraft so that it orbits the Earth.
Compare this with the conditions experienced by a craft re-entering
Earth’s atmosphere. This poses a new set of challenges. The
components and materials used in the construction of rockets and shuttles
must withstand launch and re-entry conditions.
•
describe the functions of the components of the Space
Transportation System (STS), commonly called shuttle, including:
–
the orbiter
–
solid rocket boosters (SRB)
–
external tank
•
identify some of the difficulties experienced during lift-off but not
on re-entry into the Earth’s atmosphere
•
explain why a large booster rocket is required during lift-off but not
on re-entry
•
describe properties of materials used in the STS and relate the
properties to conditions experienced during lift-off or re-entry.
•
gather and process secondary information to trace changes in the
type of systems that have been used in space travel and discuss the
advantages and disadvantages of using a shuttle
•
gather, process and present information from secondary sources on
plans for future space vehicles.
2
Space science
Gill Sans Bold
Going up
When you throw a basketball in an attempt to shoot a goal, you are
applying a pushing force to make it go up. You assume that gravity will
pull it down.
Going up always requires a force because gravity is constantly pulling
objects down. A plane gets into the air by travelling faster and faster
until the moving air keeps it up. But the air in space is too thin to support
a plane, so a plane cannot travel out of the atmosphere and into space.
Even if a plane could fly high enough, there is no oxygen in space to
burn the fuel for the plane’s engines. Soon it would stop moving and fall
back to Earth. If humans want to go into space, we need specially
designed machines called rockets.
What are rockets?
Rockets are structures containing engines that can give a spacecraft
enough power to lift-off from Earth and still work in space where there is
almost no air. Rockets can work in space because they carry their own
supply of oxygen with them. Sometimes the oxygen is compressed so
that it is liquid; and sometimes it is made from substances called
oxidisers which break down to release oxygen.
Drawing of a Saturn C class rocket, developed during the 1960s by scientists in
the USA. These launch rockets were used in the Apollo lunar landing missions.
3
How does a rocket fly?
To picture it easily, think about a flying balloon. (Try it if you like!)
What happens when you blow up a balloon and let it go? Air rushes out
of the balloon and the balloon buzzes around the room. Its forward
motion is caused by the air rushing out the back.
In a liquid rocket engine, the fuel and oxygen are pumped together and
then into the combustion chamber where the mixture is ignited.
tank
containing
oxygen
tank
containing fuel
combustion
chamber
pump
pump
exhaust jet
A rocket design.
The burning fuel in the combustion chamber produces hot gases.
These gases expand to fill a much larger space than the fuel that
produced them so the gases stream out from the tail end of the rocket at
high speed. This causes the force that pushes the rocket forward.
pu
sh
i
th ng
ru fo
st rc
e
to
w
ar
d
fo
r
ce
The force that pushes a rocket forward
(the forward force) is equal to the force
that comes out of the back of it (the
pushing force, or thrust).
For any rocket to launch successfully, its engine thrust must:
•
4
exceed rocket weight so that the rocket can rise from the launch pad
Space science
Gill Sans Bold
•
allow easy movement through the thickest part of the atmosphere
•
enable the rocket to reach orbit.
One extra advantage of rocket engines burning fuel is that they lose mass
as they use fuel.
A moving object has a certain amount of momentum.
Momentum = mass ¥ velocity = mv. As mass is lost from a moving
object the velocity increases to maintain the momentum:
mv = mv = mv
A moving object that loses mass maintains its momentum and therefore
its velocity increases.
Rocket engine types
There are two main types of rocket engine – solid and liquid propellant.
Most rockets used in space exploration are liquid propellant as the engine
can be turned on or off. Once a solid engine ignites it cannot be stopped.
liquid
fuel
tank
solid mixture
of fuel and
oxidiser
liquid
oxidiser
tank
hollow core
pumps
combustion
chamber
nozzle
(a) solid propellant
rockets
(b) liquid propellant
rockets
5
Rocket stages
Spacecraft are sent into orbit by a combination of rockets called launch
vehicles. Launch vehicles are made up of parts called stages. There are
usually three stages.
•
The first stage is the bottom and largest rocket. This is used to lift
the spacecraft initially and build up some speed. Once its fuel is
used up, this rocket drops off.
•
Then the second stage fires to gain more speed. It also uses up its
fuel and drops off.
•
The third stage continues firing until the spacecraft reaches the speed
needed to go into orbit. If any course corrections are needed, they are
carried out by small rockets placed at various points on the spacecraft.
Extra booster rockets can be placed alongside the first stage to give extra
thrust at launch time if the spacecraft is heavy.
Saturn V was the largest rocket ever built. It was designed for the
American Apollo missions to the Moon. Here are some facts about the
Saturn V rocket.
Apollo spacecraft
mass approximately 46 000 kg
Third stage
fuel mass 130 000 kg
Second stage
fuel mass 470 000 kg
First stage
fuel mass 2 200 000 kg
The total height of the Saturn V rocket plus spacecraft was 110 metres
while the total mass was 3 000 000 kg. The spacecraft was 25 metres
high. The first stage burnt approximately 15 500 kg of fuel per second.
The second stage burnt approximately 1 000 kg of fuel per second.
6
Space science
Gill Sans Bold
Use this information and the previous diagram as you answer the
following questions. These questions will help you to improve your skills
at calculating.
1
What was the height of the rocket without the spacecraft?
_____________________________________________________
2
Complete the following table. (You will need to calculate the time
to use up fuel from the other data.)
Stage
Mass of fuel
(kg)
Rate of fuel use
(kg per second)
Time to use up fuel
(seconds)
first
second
3
What was the total mass of fuel carried by the three stages?
_____________________________________________________
4
What was the mass of the rocket apart from the fuel?
_____________________________________________________
5
What percentage of the mass of the rocket is fuel?
_____________________________________________________
Please check your calculations now.
Rockets such as the Saturn V and the spacecraft they launched were
disposable. That is, they were only used once.
These single use spacecraft and rockets have been supplemented with
reusable spacecraft, commonly known as space shuttles.
7
The space shuttle
The space shuttle is a very versatile, reusable spacecraft. It is sometimes
called the Space Transportation System, or STS. It functions like:
•
a rocket during launch
•
a spacecraft as it orbits Earth
•
a truck as it transports objects to and back from space
•
an unpowered aircraft or glider as it returns to Earth.
Parts of the space shuttle
As you read about the components of the STS below, highlight or underline
the function of each part. Then summarise their functions in the table at the
end of this section.
orbiter
external tank
solid rocket booster
Main parts of the space shuttle (STS).
8
Space science
Gill Sans Bold
The shuttle is approximately 56 metres high and has a total mass of
2 million kilograms when fully assembled. The main components of the
space shuttle are the orbiter, external tank and two rocket boosters.
•
The orbiter can be described as a delta-winged space plane.
The forward section carries the crew and is about the same size as an
interstate commercial passenger jet. In the back of the orbiter is the
cargo bay where the payloads (cargo) are stored. The orbiter uses its
three engines during lift-off taking fuel from the external tank.
Fuel stored in the orbiter is used for brief engine firings in orbit and
before re-entry. The orbiter is designed to re-enter the atmosphere
and land like a glider.
•
The external tank acts like the backbone of the space shuttle.
It contains cryogenic (very cold) liquid hydrogen and liquid oxygen
required for the main engines. In order for the liquid fuel to remain
cold, the tanks are covered with insulating foam. The external tank,
made of lightweight but strong aluminium and titanium alloys, is the
only part of the space shuttle that is not reusable.
•
The two booster rockets provide about 70% of the thrust required to
lift the shuttle and external tank off the Earth.
The solid rocket boosters (SRBs) contain solid propellant,
consisting of:
–
aluminium powder, which is the fuel
–
ammonium perchlorate, which is the oxidiser to provide oxygen
–
iron oxide, which is the catalyst to speed up the release of
oxygen
–
a polymer that binds the above substances together to form a
rubbery consistency.
After separation from the space shuttle, the solid rocket boosters fall to
the ocean with the help of parachutes, where they are recovered to be
refurbished for a later space shuttle mission.
9
Summary of shuttle components
Summarise the functions of the three space shuttle components by
labelling the diagram and completing the table.
Component
Functions
Check your answers.
10
Space science
Gill Sans Bold
Launching the space shuttle
The space shuttle is specially designed so that it can go through lift-off
and re-entry many times. And so that it can carry significant payloads, it
has effective and reusable booster rockets to launch the orbiter
into space.
Boosters take the space shuttle to orbit
The orbiter’s three main engines can lift it but not enough fuel can be
stored in the orbiter for it to reach orbit. Extra fuel must be added by
means of the cryogenic hydrogen and oxygen in the external tank.
The total weight, however, exceeds the thrust capacity of the three
engines. The two solid rocket boosters provide the additional thrust.
The solid rocket boosters can lift their own weight as well as the
combined weight of the orbiter and filled external tank. They are the
most powerful solid fuelled engines ever used.
The solid rocket boosters do not contain enough propellant to enable the
shuttle to reach orbit. Hence the need for the fuel in the external tank as
well as the solid rocket boosters.
Each booster produces nearly 15 million Newtons of thrust at lift-off.
The total thrust provided by the solid rocket boosters and the main
engines exceeds 33 million Newtons. (How big is a Newton? It is about
equal to the weight force of a small apple.)
Experiencing lift-off and re-entry
The space shuttle has been designed to overcome the kind of conditions
experienced during lift-off and re-entry. Although there have been over
100 successful launches of the space shuttle, a launch is extremely
dangerous and anything but routine.
The space shuttle’s external tank alone carries nearly a million kilograms
of explosive hydrogen and oxygen. Essentially, the astronauts are riding
a huge bomb during launch.
Read the next sections that explain the kinds of conditions experienced
during lift-off and re-entry. As you read the information, underline the
difficulties that may be experienced. You’ll use the information in an
activity that follows the information.
11
Conditions during lift-off
Do you know how loud an aircraft is when it takes off? Well, the space
shuttle is much much louder. The gigantic sound produced by the roar of
the engines and the solid rocket boosters can damage the space shuttle if
it bounces off the launch area back up to the shuttle. The noise is about
100 million times louder than normal conversation.
To prevent damage, huge amounts of water are dumped into the flame
trench below the shuttle to absorb this sound. The vast white clouds at
launch are mainly steam from the engines burning the hydrogen and
oxygen fuel as well as steam from the flame trench.
About 60 seconds after lift-off, the space shuttle has accelerated past the
speed of sound. At this time the orbiter engines generate maximum
vibrations. Large aerodynamic forces can damage the shuttle by placing
huge stress on the orbiter’s wings, windshield and tail. Consequently, the
engine thrust must be throttled back from 100% to about 65%.
The ‘throttle back’ also helps to reduce the extent of heating of the
vehicle during launch.
You have already read how the solid rocket boosters are necessary to lift
the huge weight of the space shuttle, due to its required fuel load, off the
ground during launch. The rocket boosters contain a solid fuel which,
when ignited, commits the space shuttle for launch. A huge explosion
would result if it did not lift off at this point. By contrast, the main
engines on the orbiter can be throttled back and even turned off because
they use liquid fuel.
Both solid rocket boosters have nearly burned out after just two minutes.
Then small explosives disintegrate the bolts that hold the boosters to the
external tank. The still thrusting rocket boosters are pushed away from
the space shuttle by tiny rockets at the ends of each booster.
The main engines of the orbiter are cut off about eight and a half minutes
after lift-off. When the external tank has expended its fuel its connecting
bolts are disintegrated by small explosives. As it tumbles downwards
into the atmosphere, it burns up due to heating by friction with the air.
Once the orbiter gets into orbit around Earth, it travels at 8 km/s, or
28 000 km/hr, to maintain orbit. Any slower and it will fall back to
Earth; any faster and it will fly out away from Earth.
The final altitude for orbit for the space shuttle is typically 300 km above
Earth's surface.
12
Space science
Gill Sans Bold
Conditions during re-entry
Re-entry has a different set of problems from those experienced by the
space shuttle during launch. The returning spacecraft falls back to Earth
due to gravity, and 300 km is a long way to fall! The falling shuttle
passes through the atmosphere which produces its own difficulties.
The return from space involves:
•
entering the atmosphere at the correct angle
If the angle is too shallow, the space shuttle will skip off the
atmosphere like a tossed pebble skimming across smooth water.
If it is too great then the space shuttle could burn up or cause very
high ‘g’ forces. Both these could kill the astronauts
•
needing to slow down from hypersonic speeds
The shuttle needs to slow from Mach 26 (26 times greater than the
speed of sound) to subsonic speeds (less than the speed of sound) in
order to land on a small dot on Earth (the landing site)
•
an unpowered descent (no fuel required)
The shuttle simply falls through the atmosphere, approaching the
runway at six times the angle of any passenger jet. There is no
second chance for the gliding orbiter, which lands at a very fast
300 km/hr
•
using the atmosphere as a braking system
This causes super-heating of the outside of the shuttle from the
friction between the atmosphere and the orbiter as it falls
•
a communications blackout
Just when the commander wants to get as much information as
possible about the landing, communication between the shuttle and
Earth becomes difficult.
All communications must be sent via satellites, which redirect
messages between the space shuttle and mission control.
This happens because the intense heat of descent ionises the
surrounding air, changing it to a flashing glow of red, pink and
orange and disrupting direct contact.
13
Summary of difficulties of lift-off and re-entry
1
Tabulate difficulties experienced during lift-off and re-entry.
Difficulties during lift-off
2
Difficulties during re-entry
Increased ‘g’ forces are not an issue with launch or re-entry. Forces
of 2 to 3 ‘g’ only are experienced at each time. How is this
possible?
______________________________________________________
______________________________________________________
______________________________________________________
3
Unlike the launch, there is not very much vibration or sound on
re-entry. The orbiter is only just noticeable as it drops below the
speed of sound and reaches the thicker part of the air. Explain why
this is so.
______________________________________________________
______________________________________________________
______________________________________________________
Check all of your answers.
Then do Exercise 4.1.
14
Space science
Gill Sans Bold
Materials used in the space shuttle
The materials used in the space shuttle (STS, or Space Transportation System)
have been chosen or designed to overcome problems that the craft may experience.
Highlight or underline examples as you read about properties of some of the
materials used in the STS. Use the information to complete the summary at the
end of this section.
Materials in the orbiter
The majority of the orbiter’s structure (body) is welded aluminium
covered with an aluminium skin. The wings and tail are made from
honeycombed aluminium panels. Aluminium is used because of its:
•
lightness
•
resistance to corrosion
•
durability
•
strength.
This lightweight construction reduces weight for launch while still
ensuring high strength. The orbiter’s aluminium skin is protected by
surface insulation, which is in the form of:
•
reinforced carbon-carbon fibre
This is used on leading edges, such as the wings and nose cap, as
well as the lower area where the external tank is attached
•
felt blankets
•
about 25 000 tiles
The black and white tiles are made from sand refined into pure silica
fibres, which protect the undersurface of the orbiter.
During the fiery dive of re-entry through Earth’s atmosphere, the orbiter
will experience extreme heating that is sufficient to melt the orbiter’s
aluminium cover. The tiles that protect the orbiter from overheating
during re-entry have a black glass coating for efficient radiation of heat.
Those tiles for lower temperature areas are coated with a white silica
compound to better reflect the heat of the Sun while in orbit.
A tile’s effectiveness at preventing the orbiter’s aluminium structure
from melting is spectacularly shown by heating a tile until it is red hot.
The tile sheds heat so readily that the tile will be cool to the touch in only
a few seconds while its interior is still glowing red. (Don’t try it!)
15
Black tiles are used on the upper forward part and around the windows.
Black is a more efficient radiator of heat rays than white. White tiles, a
good reflector of heat rays, are used where the shuttle does not get so hot.
The strong windows of the orbiter are made from a thick glass of
aluminosilicate and fused silica. This glass is designed to withstand
pressure and heat shock while providing crystal clear views and
high efficiency reflection of heat.
Materials in the external tank
The external fuel tank is made of very light but strong aluminium and
titanium alloys. This also ensures the overall lightness of the space
shuttle without compromising strength.
Materials in the solid rocket boosters
The solid rocket boosters are made of stainless steel. This gives the high
strength needed for the launch and for the splash down collision with the
ocean. It also provides heat resistance and ease of refurbishment for the
future reuse of the boosters.
Summary of materials in the space shuttle
Complete the table below to relate materials in the STS with conditions
during lift-off or re-entry. Relate the properties to conditions experienced
during lift-off/re-entry in the third column.
Material in shuttle
Properties of material
Need for material
during lift-off/re-entry
aluminium structure
of orbiter
carbon-carbon fibres on
leading edges and
external tank attachment
black silica tiles on the
orbiter
16
Space science
Gill Sans Bold
white silica tiles on the
orbiter
aluminosilicate and
fused silica windows
aluminium/titanium
alloys in external fuel
tank
stainless steel
booster rockets
Check your answers.
Advantages and disadvantages of
the space shuttle program
The space shuttle is the most capable and most complex vehicle built
since the space program began. It is the first reusable space vehicle and
has been a major means of providing humanity with benefits from space
exploration.
Some uses of the space shuttle include:
•
laboratory research for space, military and commercial use
•
scientific studies including life sciences, materials sciences, combustion
science, solar science, physics, plasma science, behaviour of metals,
study of semiconductors, behaviour of fluid in low gravity conditions,
atmospheric studies, manufacturing of pure crystals for medicines,
study of the growth of cancerous tissue; and the list goes on
•
deployment and repair of satellites, for example, for communication,
Earth observation and astronomy (The interplanetary spacecraft
Galileo sent to Jupiter and the orbiting satellite observatory, the
Hubble Space Telescope were launched from the space shuttle.)
•
transportation of parts required for the construction of an
international space station.
17
1
Make your own list of advantages of using the space shuttle for travel to
and from space.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
2
What are some disadvantages of using the space shuttle for travel to and
from space?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
18
Space science
Gill Sans Bold
The changing nature
of space flights
Changes up to the present
The most significant crewed space flights to date have been in the Apollo
program. This United States program involved human exploration of the
Moon in the late 1960s and early 1970s.
In the quest to land humans on the Moon, two spacecraft were launched
on top of the extremely powerful multistage Saturn V rocket.
These spacecraft were:
•
The Apollo spacecraft, which consisted of two parts attached to
each other.
Three astronauts occupied the cone-shaped capsule called the
command module. (See the photograph earlier in this part.)
Attached to the bottom of the command module was a cylindricalshaped service module, which provided electricity, oxygen and other
support functions for the astronauts as well as propelling the rocket
so that it could achieve lunar orbit.
•
The second spacecraft, called the lunar module, was used to provide:
–
a safe landing onto the Moon (the landing gear of this module
was left behind on the Moon’s surface)
a successful launch from the Moon’s surface in the detachable
cabin of the lunar module.
Returning to Earth first required the undocking of the ascent stage of the
lunar module that lifted astronauts from the Moon's surface.
Again, re-entry involved a fiery fall through the atmosphere, slowed by
parachutes to a splashdown in the ocean.
19
A lunar landing module in the Smithsonian museum, Washington
(Photo: by Rhonda Caddy.)
The present day STS evolved from a series of space projects dating
back to the very first space flights with humans on board in the 1960s.
In the 1960s and 1970s improvements in launch vehicles were swift
and dramatic but these spacecraft were not reusable. In 1981, the first
partially reusable launch vehicle, the American space shuttle,
was introduced.
The Russians have used non-reusable, multistage launch vehicles, with
strap-on boosters. These can be used as crewed or uncrewed supply craft
for space stations. The landing module descends through the atmosphere
with the assistance of a heat shield, a parachute and a last minute blast
from rockets situated in the base to cushion the final touchdown.
Look at some of the links for Part 4 of Space Science at www.lmpc.edu.au
then complete Exercise 4.2.
20
Space science
Gill Sans Bold
Changes into the future
There have been no significant changes to the systems required for
people to travel in space since the space shuttle. The reliability of this
ageing technology and the high cost of replacement has seen this system
in use for decades.
However, research continues into the development of new space
transportation systems, to overcome the limitations of present equipment
and to increase the possibilities for space research and exploration.
Planned reusable launch vehicles (RLV)
The space shuttle is known as a first generation reusable launch vehicle
(RLV) even though the external tank is discarded with each mission.
The STS system will only be replaced if new technology is developed
that gives:
•
greater affordable access to space
•
greater reliability and safety
•
a lightweight thermal protection system using composite materials
•
a propulsion material that will reduce weight but improve carrying
capability.
In order for cost-effective launches of space vehicles to occur, single
stage-to-orbit vehicles must be developed. This means that the vehicle
would launch from Earth without a disposable fuel system, orbit in space
and return as the same vehicle that was launched.
The Lockheed Martin X–33 reusable launch vehicle was an unpiloted
vehicle designed for such purposes. The project aimed at reducing the
cost of launching cargo into orbit from $US25 000 per kilogram to
$US2 500 per kilogram in the year 2000 dollars. This transport system
was expected to fly every two weeks rather than only a couple of times
each year.
The unpiloted X-34 was another vehicle design. It was an example of a
low cost reusable launch vehicles.
The X-33 and X-34 projects were cancelled in 2001 but the X-37
reusable launch vehicle project continues.
21
X–33
X–37
X–34
RLV designs
Plans for future space vehicles
The cost of research and development to overcome the huge technical
challenges seems to be the delaying factor for the construction of other
reusable launch vehicles. So predicting the future of space transportation
is very difficult.
International designers will be looking at spaceliners that can take off
from an airport, fly into orbit and land at an airport in order to make
flights between continents faster than they are today. At present, large
passenger jets fly at only Mach 1 (travelling at the speed of sound).
Even the Concorde jet travels at only just over Mach 2.
NASA is developing a vehicle with scramjet (supersonic combustion
ramjet) engines but it is not one that will be launched from Earth.
It needs to be launched from another aircraft at high altitude. If an
aircraft with scramjet engines flew overhead like a normal aeroplane, it
would cause windows to break, maybe buildings would be destroyed,
trees would be flattened and human eardrums would be ruptured.
A ramjet has no moving parts. Air rams into the engine as a result of
prior movement of the engine through the air, fuel is injected and the hot
expanding gases force the engine forward.
A scramjet is a Supersonic Combustion ramjet. The air into which the
fuel, normally hydrogen gas, is injected is moving at supersonic speeds.
22
Space science
Gill Sans Bold
A diagram of the NASA X-43c scramjet is shown below:
In 2002 a test carried out by a University of Queensland team demonstrated
that they had developed the most advanced form of scramjet engine.
Find out more about their design and its testing at Woomera rocket range in
South Australia at http://www.lmpc.edu.au/Science.
Make a summary about plans for future space vehicles using the information
provided in this section. Look for additional information in other sources,
such as the Internet. Complete Exercise 4.3.
23
24
Space science
Gill Sans Bold
Suggested answers
Rocket stages
1
85 m (110 – 25 = 85 m)
2
The completed table is below. To find the time (in the last column),
you needed to divide the mass of fuel by the rate at which it was
used.
Stage
first
second
Mass of fuel
(kg)
Rate of fuel use
(kg per second)
Time to use up fuel
(seconds)
2 200 000
15 500
142
470 000
1 000
470
3
2 800 000 kg (2 200 000 + 470 000 + 130 000 = 2 800 000 kg)
4
200 000 kg (3 000 000 – 2 800 000 = 200 000 kg)
5
93%
( 2800000 ¥ 100 = 93% )
3000000
1
25
Summary of shuttle components
Check your diagram labels against the labels on the page 9 diagram.
Component
Functions
orbiter
craft that goes into orbit; carries
payload and crew; returns to Earth
external tank
carries fuel for journey after lift-off;
acts as backbone for shuttle during
launch
solid rocket boosters (SRB)
provide extra energy to lift the shuttle
from Earth; fall back after launch to be
reused
Summary of difficulties of lift-off and re-entry
1
Here is an example of a completed table.
Difficulties during lift-off
Difficulties during re-entry
•
engine vibration can damage
space shuttle
•
must enter Earth’s atmosphere
at the correct angle
•
the need to get a large enough
force to lift the STS up away
from Earth
•
the orbiter has to slow from its
orbit speed
•
•
forces to lift the STS can cause
damage to the orbiter
there is only one chance of
landing because the orbiter falls
and glides
•
fuel for the STS is explosive
•
•
the launch cannot be cancelled
once the booster rockets are
fired, no matter what problems
occur
the orbiter is heated by friction
with the atmosphere as it falls
•
communication is difficult
during re-entry
•
2
26
the orbiter must speed up to
reach and maintain the correct
orbit speed
The lift-off and re-entry speeds are controlled so that the astronauts
are not subjected to high ‘g’ forces. Larger forces would occur if all
the rockets fired together at full-throttle after lift-off or if the orbiter
landed at a faster speed. Larger forces could crush the astronauts.
Space science
Gill Sans Bold
3
Sound is passed through the air by vibrating air particles. There are
hardly any air particles to vibrate until the orbiter reaches the thicker
part of the atmosphere. Because the orbiter is travelling so quickly,
this happens very close to landing time.
Summary of materials in the space shuttle
Here is an example of a completed table.
Material in shuttle
Need for material
during lift-off/re-entry
aluminium structure
of orbiter
light; strong; durable;
corrosion resistant
light so it can lift off;
strong to withstand
forces of lift-off and
re-entry; durable and
corrosion resistant for
reusability
carbon-carbon fibres on
leading edges and
external tank attachment
strong; insulating
protect edges of wings
and nose cap; give
strong attachment of
external tank
black silica tiles on the
orbiter
radiate heat; insulating
shed heat during launch,
orbit and particularly, on
re-entry
white silica tiles on the
orbiter
reflect heat; insulating
reflect heat during
launch and orbit
aluminosilicate and
fused silica windows
strong; heat and
pressure resistant;
transparent
provide visibility during
mission and particularly,
for re-entry and landing
aluminium/titanium
alloys in external fuel
tank
light; strong
light for lift-off; strong to
provide rigidity for entire
STS during launch
stainless steel in
booster rockets
strong; heat resistant;
easy to reuse
operate during high
forces of lift-off; fall back
to Earth without burning
or bending
27
Advantages and disadvantages of the space shuttle
program
28
1
Advantages of the STS include that it: is reusable; gives convenient
access to a wide range of experiments in space; enables deployment
and repair of satellites; is used as a transport vehicle for building a
station in space.
2
Disadvantages of the STS include that it: is costly; is dangerous for
astronauts (and potentially for others if debris falls to Earth);
produces reliance on the USA for space exploration and research.
Space science
Gill Sans Bold
Name: _________________________________
Exercise 4.1
a)
Label the parts of the STS with their functions.
b)Using the space shuttle as an example, explain why a large booster
rocket is required during lift-off but not on re-entry.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
29
c)
Identify some of the difficulties experienced during lift-off but not
on re-entry.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Exercise 4.2
List changes in the types of systems that have been used in space travel.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Exercise 4.3
Outline plans for future space vehicles. Include information about future
RLVs and how these spacecraft could be different from the STS.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
30
Space science
Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
Part 5: Space exploration
2
0
0
I
2
r
be S
o
t
c NT
O
ng DM E
i
t
ra E N
o
rp A M
o
nc
Gill Sans Bold
Contents
Introduction ............................................................................... 2
The history of space exploration ............................................... 4
Optical telescopes ..................................................................... 5
Refracting telescopes...........................................................................5
Reflecting telescopes ...........................................................................6
Modern optical telescopes ...................................................................8
Space telescopes .................................................................................9
Beyond light observations ....................................................... 11
Radio telescopes................................................................................13
Very long baseline interferometry......................................................15
Going into space ..................................................................... 18
Space probes .....................................................................................18
Space stations....................................................................................20
Australia’s involvement with space research........................... 24
Is anyone out there?................................................................ 29
Exercises – Part 5 ................................................................... 37
1
Introduction
In this part of the module you will learn about the developments in
technology that have led to a greater understanding of the components
seen in the night sky. Note that some information and skills to complete
the exercises are spread throughout Part 5. You will need to draw
together these ideas towards the end of this part. No special equipment is
needed for Part 5 activities, just everyday objects.
•
discuss requirements that would be necessary to sustain human life
for months or even years on a space station
•
identify the space stations already used in space
•
outline how information is transmitted between Earth and the space
stations
•
describe and account for the advantages of building optical
telescopes on high mountains
•
identify the type of information gathered about space by
•
–
Hubble Telescope
–
Very long baseline array (VLBA)
–
Highly Advanced Laboratory for Communications and
Astronomy (HALCA) satellite working with ground-based
satellites (GBS)
discuss the value of Search for Extraterrestrial Intelligence (SETI)
and Optical Search for Extraterrestrial Intelligence (OSETI) projects
to identify life and advanced civilisations in the Universe.
•
2
gather and analyse information from secondary sources to present an
overview of the roles of the Voyagers 1 and 2 space probes and how
our understanding of the solar system and universe was furthered by
these space missions
Space science
Gill Sans Bold
•
trace the developments in technology that have enabled us to identify
the different components in the night sky
•
gather and process information from secondary sources to identify
the methods employed over time to collect information about our
solar system and beyond
•
gather and process information from secondary sources to trace
Australia’s involvement in space exploration.
3
The history of
space exploration
Space exploration would have begun with the human eye. Can you
imagine what it must have been like for the first humans who ever looked
up and thought about the heavens?
The day began when the Sun came up and once the Sun went down,
everything was dark. There was only firelight. The night sky was the
most outstanding visual experience of the evenings.
Go outside on the next clear night and have a long look at the sky. You will
be looking at the beautiful heavens, especially if you live far away from the
big city lights. So go and have a big long look. Go on, have a look!
Make a list of all the different kinds of things that you saw and can name
in the sky.
_________________________________________________________
_________________________________________________________
Today space exploration is achieved using a vast array of technologies.
Optical and radio telescopes are used on Earth, while out in space there
are telescopes on satellites, and instruments and probes on spacecraft.
4
Space science
Gill Sans Bold
Optical telescopes
From early in the seventeenth century until the middle of the twentieth
century practically all technological developments enabling identification
of the different components in the night sky involved telescopes using
light. This section deals with the technological development of light
detecting telescopes. Today optical telescopes can detect stars with a
brightness a millionth of what the human eye can see unaided.
In 1608, a Dutch lens grinder by the name of Hans Lippershey constructed
an instrument that magnified the images of distant objects. This new
invention was called a spyglass.
Six months later, the famous Italian scientist, Galileo, began constructing
telescopes and built one that had a magnification of about thirty times.
He is credited as having been the first person to turn a telescope on the
heavens to study celestial objects.
Galileo made revolutionary changes to night sky observations using this
new device by magnifying space images. He discovered the four major
moons of Jupiter, described sunspots and found that the planet Venus had
phases like those of the Moon. Galileo described Saturn as having
handles, or ears. (Today they are called rings.) Galileo’s observations
with a simple telescope confirmed that the Earth was not the centre of the
observable universe.
Refracting telescopes
Galileo’s telescope used pieces of curved glass (that lens makers used) to
focus light from images in space. This type of telescope is called a
refracting telescope, or refractor.
Here is a diagram showing what happens in a refracting telescope.
5
convex lens
image
refracted light forms an image
that the astronomer observes
light from space
travels to the lens
Light in a refracting telescope is bent inwards to a focal point by a lens.
Demonstrating a convex, or converging, lens
You have probably used a magnifying glass before but here is an activity to
help focus your ideas about lenses.
•
a drop of water
•
a piece of clear plastic
•
a sheet of printed paper.
What to do:
Simply place a drop of water on the plastic then hold the drop over a
sheet of printed paper, such as this one.
What do you notice?
_________________________________________________________
_________________________________________________________
Check your answer.
Reflecting telescopes
In 1668, Isaac Newton built a telescope that used a mirror instead of a
lens. The larger the main mirror, the greater the light-collecting ability of
the telescope. The more light that is collected, the brighter the image that
will form of the celestial object. Hence, more information is obtained
from the night sky.
The type of mirror used in a reflecting telescope is called a concave
mirror. Its shape is designed to focus the image at a point that can
be observed.
6
Space science
Gill Sans Bold
concave
mirror
light from space
travels to the mirror
image
reflected light forms an image
that the astronomer observes
Light in a reflecting telescope is bounced back by a mirror to a focal point.
Newtonian telescopes
Here is a diagram of the telescope invented by Isaac Newton. It is called
the Newtonian reflecting telescope. Most large astronomical telescopes
are Newtonian or similar types.
plane mirror to bounce light
to the observer’s eye
parallel light rays
from a star
eyepiece lens
main curved mirror to
collect light from the sky
and focus it onto a point
A Newtonian reflecting telescope.
Adapted from OTEN, Physics for Electrical and Electronic Engineers.
Here is a photograph of a
modern Newtonian
telescope. This telescope is
used by an amateur
astronomer. It produces
good, clear images of
celestial objects such as the
Moon, planets and comets.
Amateur astronomers, using
telescopes like this, have
made important
contributions to the science
of astronomy.
(Photo: by Ric Morante ©LMP)
Astronomical telescopes are generally much larger than this amateur
telescope. The main mirror in astronomical telescopes is coated with
aluminium to produce a silvery reflecting surface that should be kept
clean and never touched.
7
Position, position, position
Light from objects in space must travel through the atmosphere before it
can be observed using optical telescopes on Earth. The best sites for
optical telescope observatories are remote places that:
•
are as high as possible with still air, to decrease the scattering of
light due to disturbances in the atmosphere
•
have a dry climate to cut down the amount of light that can be
absorbed by water in the air
•
are as distant as possible from brightly lit cities, which cause
light pollution.
Describe and account for the advantages of building optical telescopes
on high mountains.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
Modern optical telescopes
Today, astronomers do not look through telescopes very often. They still
use optical telescopes but most use photographs or, more recently,
computers to record what is being observed. The largest optical
telescopes have Keck reflectors with mirror diameters of 10 m. They are
located on Mauna Kea in Hawaii and in the Atacam desert in Chile, at
altitudes of around 4 000 m.
The largest optical telescope in Australia is the Anglo-Australian
Telescope on a mountain at Siding Springs, near Coonabarabran in New
South Wales. It has a 3.9 m diameter main mirror.
Some major reflecting telescopes outside Australia are:
8
•
Keck Telescopes in Hawaii using two 10 m mirrors
•
the very Large Telescope in Chile using four 8.2 m Keck mirrors
that can work independently or together
•
4.2 m William Herschel Telescope in the Canary Islands
•
2.4 m Hubble Space Telescope in low earth orbit.
Space science
Gill Sans Bold
Astronomers favour reflecting telescopes because mirrors can be
supported from behind but lenses can only be supported at the thin, very
fragile edges. Mirrors can be made more quickly and easily whereas
large glass lenses take years to make. However, large refracting
telescopes with lenses up to about one metre in diameter are still used
when high quality images are needed of objects nearer to Earth.
The Keck mirror is not made in
one piece. Large mirrors sag
under their own weight and
cannot reflect light accurately.
Instead, the Keck telescope
mirror is made from 36 hexagonal
(six-sided) mirrors as shown.
A slightly larger 10.4 m telescope
based on this design should be
operating in the Canary Islands
in 2004.
Hexagonal mirrors make up one very
large mirror.
The optical telescope became the most important tool available to
astronomers for looking at the objects they study. As astronomers learnt
how to collect more starlight, they discovered more celestial objects and
were better able to understand the Universe.
Space telescopes
Space telescopes are telescopes on satellites or spaceships out in space.
They are the best kind to use for observing. This is because there is no
atmosphere to scatter light and make optical images blurry.
The Hubble telescope
The most famous space telescope is the Hubble Space Telescope, which
mainly collects visible light but also infrared and ultraviolet energy.
Hubble was launched by the Space Shuttle Discovery on 24 April 1990 and
placed in a 300 km high Earth orbit on 25 April.
Although the Hubble telescope is not as large as the largest ground-based
telescopes (the Keck telescope has 16 times the light-gathering power of
9
the Hubble), it can outperform any of them. It has collected invaluable
information about planets, comets, nebulae, galaxies and stars.
Comparing images
Rising from a sea of dust and gas like a giant seahorse, the Horsehead
Nebula is one of the most photographed objects in the sky. The shape is
an extension of a large cloud of dust that hides the light of stars beyond.
The Hubble telescope took a close-up look at the cloud's intricate
structure on 25 April 2001 to celebrate the orbiting observatory's
eleventh anniversary.
Would you like to look at this and other images collected by the Hubble
Space Telescope? You can access the Hubble site from:
10
Space science
Gill Sans Bold
Beyond light observations
You have seen that optical telescopes are very useful for collecting light
from the Universe and forming images that astronomers can see clearly.
What other kinds of radiation can be used to obtain information about
the Universe?
Stars also give off other kinds of radiation, such as gamma rays, X-rays,
ultraviolet, infrared, microwave and radio. You will recognise all these
kinds of radiation as examples of electromagnetic radiation.
ENERGY INCREASES
105
108
1010
1013
radio waves
radio
106
103
TV
100
Frequency in cycles per second
1019
1015
1017
light
microwaves
10–2
infrared
10–5
visible
102
X-rays
gamma rays
ultraviolet
10–7
10–9
Wavelength in metres
10–11
The spectrum of electromagnetic radiation.
You can see from the spectrum above that there is lots more information
available than can be collected with optical instruments.
1
Look back at the information about the Hubble telescope.
a) Which types of electromagnetic energy does it collect?
__________________________________________________
b) What are some objects that have been studied using the Hubble?
__________________________________________________
__________________________________________________
Check your answers.
Most types of electromagnetic radiation cannot penetrate the atmosphere.
Look at the diagram below that shows the extent of penetration of
11
gamma rays
400
X-rays
UV
visible light
radiation at different wavelengths through Earth’s atmosphere.
The darker the shading the greater the amount of absorption.
infrared microwave
radio
Altitude in km (not to scale)
200
100
50
25
12
aircraft
6
3
land surface
0
sea level
wavelength
Penetration of radiation of different wavelengths through Earth’s atmosphere.
2
Which kinds of radiation from space (other than light) would be better
observed by space-based telescopes? Explain why.
_____________________________________________________
_____________________________________________________
3
What types of electromagnetic waves penetrate to the Earth’s
surface?
______________________________________________________
______________________________________________________
Check your answers.
12
Space science
Gill Sans Bold
Radio telescopes
The diagram on the previous page shows that radio waves as well as light
waves are not absorbed in the atmosphere and so can reach the Earth’s
surface. The fact that many astronomical objects emit radio waves as
well as light waves was not discovered until 1932. Since then,
astronomers have developed sophisticated systems that allow them to
make pictures using radio waves from space.
Radio astronomy has developed into one of the most exciting and
useful branches of astronomy because objects that are invisible to the
optical astronomer ‘come alive’ when viewed at radio wavelengths.
Some celestial objects emit more strongly at radio than at
light wavelengths.
By studying the sky with both radio and optical telescopes, astronomers
can gain a much more complete understanding of the Universe.
How does a radio dish work?
Radio telescopes work just like the concave mirrors in reflecting light
telescopes. They receive weak radio signals from space, which hit its
surface as parallel rays. The dish collects the weak intensity signals and
focuses them by reflection to a receiver aerial at the focus, or focal point,
of the dish. This increases the strength of the signal received.
Label the following parts of this radio dish: dish, parallel radio waves
from space, reflected radio waves and focal point (where radio information
is received.)
Check your answer.
13
One of the largest, most sensitive radio telescopes in Australia is near
Parkes, New South Wales. It is 64 m wide so that it can pick up faint
signals from a long way out in space.
` Bartsch )
(Photo: Baska
Radio telescopes are not only used to collect radio information from
distant stars. They are also very important for telecommunications
between spacecraft and earth bases. Messages – both sound and pictures
– can be transferred through space using radio waves as the carrier.
Radio waves can also be sent between computers so that scientists on
Earth can alter settings on satellites, space probes and spacecraft out
in space.
How does this work? It is easy to convert information in sound, video
and electrical impulses to be carried by radio waves. (Radio and TV
broadcast stations do it all the time!) Radio waves can be transmitted
over very long distances and they travel better through space than
through the atmosphere here on Earth. They can be amplified and
reflected off satellites so that they can be passed as clear messages
between space-based objects and ground-based radio telescopes.
If you would like additional information about the transfer of information
using radio waves, refer to the HSC module called Information systems.
Radio telescopes play an important role in communicating with
astronauts and space-based telescopes and probes. They act like Foxtel
or Austar satellite dishes, collecting information as radio waves and
converting it into messages that people can use and understand.
The biggest difference between a radio telescope and a TV satellite dish
is that a TV dish is small enough to sit on the roof of your house!
14
Space science
Gill Sans Bold
Although single radio telescopes are very useful, scientists have developed
ways to use systems of radio telescopes to increase their ‘view’ of the sky.
This technique is called very long baseline interferometry (VLBI).
Very long baseline interferometry
The technique of very long baseline interferometry uses widely spaced
telescopes to synthesise a telescope as large as the greatest distance
between the farthest telescopes. The reason for doing this is to study
celestial radio sources in more detail.
VLBA
The Very Long Baseline Array (VLBA) is a system of ten radio
telescopes ranging from Hawaii to the Virgin Islands. Remotely
controlled from the Socorro, New Mexico, they have worked together as
one of the world’s largest, full-time astronomical instruments since 1993.
The map below shows the position of each of the ten VLBA stations.
They each consist of a 25 m diameter dish, antenna and equipment
associated with collecting the radio signals gathered by the antenna.
An antenna is pointed straight up is nearly as tall as a ten storey building.
The Very Long Baseline Array
Brewster Washington
Hancock New Hampshire
North Liberty Iowa
Owens Valley California
Los Amos New Mexico
Mauna Kea Hawaii
Pie Town New Mexico
Kitt Peak Arizona
Fort Davis Texas
St Croix Virgin Islands
15
Draw the ‘baseline’ for the VLBA system onto the map. It is the line that
joins the two most distant telescopes. It is also the diameter of the dish
synthesised by the system. Sketch in the dish created by VLBA.
The VLBA can show new details of the powerful cores of distant
quasars, which spew out tremendous amounts of energy. It can make
precise measurements of the speed of debris from supernovae and gaze
into the heart of a galaxy. Can it help scientists to work out the size of
our Universe?
The VLBA’s sharp vision, or high resolution, is an ideal tool for learning
new things about a wide variety of astronomical objects and processes.
Radio information is used to build colour pictures of objects in space.
Would you like to see some of these images? You can access radio
images from other Internet sites at: http://www.lmpc.edu.au/Science
What kinds of information are gathered by the VLBA?
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
VLBI has been so effective that scientists have extended the technique by
adding a space-based radio telescope. This makes the baseline, and so
the synthesised dish size, much much larger.
HALCA
The Highly Advanced Laboratory for Communications and Astronomy
(HALCA) is a radio astronomy satellite in orbit around Earth. (When it
was launched in February 1997, it was called Muses-B.)
HALCA is a space observatory in an elliptical orbit with a maximum
distance of 21 000 km from Earth’s surface. This satellite’s observations
are carried out in conjunction with ten ground-based radio telescopes
(called ground-based satellites, or GBS) positioned around Earth.
Information from HALCA is added to radio observations by the GBS
on Earth. This enables VLBI (very long baseline interferometry) up to
three times longer than that achievable using ground-based radio
telescopes alone. Here is an analogy: using HALCA and the GBS is
equivalent to being able to read a newspaper in Sydney from Perth!
16
Space science
Gill Sans Bold
HALCA
makes a radio telescope
three times larger than Earth
ground-based
satellites (GBS)
HALCA’s
orbit
The elliptical orbit of HALCA allows imaging of celestial radio sources by the
satellite and ground-based satellites (GBS).
The Universe is a natural laboratory unlike anything that humans can
build, with tremendous temperatures, pressures, densities and powerful
electric and magnetic fields. Combining HALCA and the VLBA gives
scientists the most powerful tool currently available for gaining new
knowledge about the Universe.
What kinds of information do HALCA and the GBS gather?
_________________________________________________________
_________________________________________________________
Check your answer.
When you think about it, Earth is a long way from anywhere in the
Solar System, let alone in the Universe! Optical and radio telescopes,
even space-based ones, are limited when they can only look at the
Universe from the space on and around Earth.
17
Going into space
Space research became even more technologically complex when devices
were sent into space to collect information.
Space probes
Robotically controlled, space-exploring machines called space probes have
examined every planet in the Solar System except Pluto. They have also
provided information about the Sun, comets, asteroids and many of the
planets’ moons. Voyager 1 and Voyager 2 are examples of space probes.
These automated explorers have collected information that show that our
solar system is very different from what was believed just 30 years ago.
The following table shows a brief summary of some space probe
programs. It gives you some idea of the extent of investigation that is
possible using a space probe. Some probes have actually left our solar
system and are on their way to distant stars.
Some space probe programs
18
Program
(Country)
Launch dates
Missions and accomplishments
Pioneer
(USA)
1958–60,
1965–69,
1972–73,
1978
Pioneers 1 to 4 (1958-59) were
unsuccessful Moon missions. Successful
missions included the first deep space
probe (Pioneer 5, 1960); first fly-by of
Jupiter (Pioneer 10, 1973) and of Saturn
(Pioneer 11, 1979); first radar probe of the
surface of Venus (Pioneer-Venus 1, 1978)
Space science
Gill Sans Bold
Luna
(USSR)
1959,
1963–66,
1968–76
first to land on Moon and photograph
Moon’s far side (Luna 1, 2 and 3, 1959);
first to achieve lunar orbit (Luna 9 and 10,
1966); first lunar soil sample collected and
returned, and surface exploring vehicle
(Luna 16 and 17, 1970)
Mars
(USSR)
1960, 1962,
1969, 1971,
1973
first to enter the atmosphere of Mars
(Mars 6, 1973)
Ranger
(USA)
1961–62,
1964–65
first to return thousands of clear
photographs of the Moon (Ranger 7,
1964)
Venera
(USSR)
1961–62,
1965, 1967,
1969–70,
1972,1975,
1978, 1981
first to successfully enter the atmosphere
of Venus (Venera 4, 1967); first to reach
the surface of Venus intact (Venera 7,
1970); first to return TV pictures from
Venus' surface (Venera 9, 1975)
Mariner
(USA)
1962, 1964,
1967, 1969,
1971, 1973
first successful fly by of Venus (Mariner 2,
1962) and of Mars (Mariner 4, 1964); first
to orbit another planet (Mariner 9; 1971);
first fly by of Mercury, first to visit two
planets during a mission (Mariner 10,
1973)
Program
(Country)
Launch dates
Missions and accomplishments
Zond
(USSR)
1964–65,
1967–70
Zonds 1 and 2 (1964) were unsuccessful
Venus and Mars missions. First to fly
around the Moon and return to Earth
(Zond 5, 1968)
Lunar Orbiter
(USA)
1966–67
lunar orbiting probes looked for landing
sites for the Apollo mission and
photographed 95% of the Moon’s surface
Surveyor
(USA)
1966–68
first to return thousands of pictures of the
Moon’s surface (Surveyor 1, 1966); first
chemical analysis of the Moon’s soil
(Surveyor 5, 1967)
Viking
(USA)
1975
first successful Mars landing to perform
experiments, to take photographs and to
send TV pictures of the surface of Mars
(Vikings 1 and 2, 1976)
19
Voyager
(USA)
1977
1979–8
1986, 1989
discovered Jupiter's rings, investigated
Saturn's rings, identified new moons of
Jupiter, Saturn and Uranus (Voyagers 1
and 2)
Magellan
(USA)
1989
1990–92
1993–94
radar mapping of the surface of Venus;
measurements of gravitation of Venus;
used friction with Venus’ atmosphere to
change path of the probe
Ulysses
(USA, European
Space Agency)
1990–
collected information about the Sun and
studied Jupiter's magnetic field
Mars Observer
(USA)
1992-1993
unsuccessful mission
Comment on the value of space probes in space exploration.
_________________________________________________________
_________________________________________________________
Check your answer then complete Exercise 5.2.
Space stations
Have you seen any movies where people get off at a space station before
embarking on the next leg of their space journey? The idea of space
stations permanently occupied by humans has been around since the
beginning of space travel.
The USSR turned the idea of space stations into reality when it launched
Salut-1 in 1971. The USA’s first space station, Skylab, was occupied
during 1973 and 1974. Since then, two other space stations have orbited
Earth – the Russian Mir and the International Space Station (ISS).
Space stations use the weightless environment of space to conduct a wide
range of experiments. They are also a perfect platform for observations
of Earth. Space stations could eventually form the basis of a space
manufacturing industry.
Do you know somebody who may be interested in space stations?
Try to find such a person for a discussion. Discuss the requirements that
would be necessary to sustain human life for months or even years on a
space station. This could help you later in completing Exercise 5.7.
20
Space science
Gill Sans Bold
Mir
Mir was the first stage of a new generation of space stations, launched in
1986. Mir was a space structure that could be built and assembled in
stages and was permanently occupied by cosmonauts and astronauts from
around the world for over 12 years. Notice the modular, or staged,
structure of Mir.
Here is an article that a student wrote about Mir for a school newspaper.
As you read, highlight or underline information that you will include in
a summary.
Mir history
by Brook O’Connell
On 20 February 1986, the Soviet Union announced the launch of this new
space station called Mir, which means ‘peace’ in Russian. This space
colony will go down in history as the first stepping stone towards the
migration of humans off planet Earth.
Mir was constructed in orbit over the next 10 years. It was built as a 20 ton
core module with six docking ports for transport craft and future add-on
modules. It could be resupplied by robotic Progress freighters, which
carried fuel, oxygen and other essentials. Mir dwarfed anything previously
built in space and when it was completed in 1997, it weighed 137 tons.
Mir was originally planned to last 5 years but with the help of mission
controllers, cosmonauts kept the station going three times as long and set
several records in space history. The most remarkable record was Valeriy
Polyakov’s marathon stay of 438 days.
The worst things that could happen in space did happen, aboard Mir. The
station’s troubled life of accidents, malfunctions and near-disasters was
well documented in the news back on planet Earth. In February 1997, an
on-board fire roared through one of the station’s six pressurised modules,
nearly forcing its six occupants to abandon ship. Then, in June of that
year, an robotic supply ship collided with Mir during a docking attempt,
plunging American Michael Foale and his Russian crewmates into a long
struggle to save the station and their own lives.
Mir’s achievements, however, are fascinating. 104 cosmonauts and
astronauts from 12 countries spent a total of 4 591 days (more than 12
years) aboard the station. They performed 23 000 separate scientific
experiments and made 78 space walks totalling 352 hours.
By the time the station’s adventures ended, with the break-up of the station
and its fiery fall to Earth in 2001, 3.5 billion kilometres had been covered.
21
Write your summary about Mir here.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
The International Space Station
The United States and Russia have partnered together since 1994,
performing nine Shuttle-Mir dockings. This provided valuable
experience for gaining the knowledge and teamwork necessary for
building and maintaining the International Space Station.
Representing a global partnership of 16 nations, it will eventually include
six laboratories and provide more space for research than any spacecraft
ever built. Internal volume of the space station will be roughly equal to
the passenger cabin volume of a 747 jumbo jet.
More than 40 space flights over five years and at least three space
vehicles – the space shuttle, the Russian Soyuz rocket and the Russian
Proton rocket – will deliver the various space station components to
Earth orbit. Assembly of the more than 100 components will require a
combination of human space walks and robot technologies.
The International Space Station is under construction and is permanently
occupied by teams of astronauts. When the space station is completed, an
international crew of up to seven will live and work for between three and
six months in space. Crew vehicles will always be attached to the space
station to ensure the safe return of all crew members in an emergency.
Would you like to find out what is happening on the International Space
Station, right now? You can access the NASA site from:
22
Space science
Gill Sans Bold
Time to pull together some big ideas
So far in Part 5, you have learnt about a variety of technologies that have
been used, and are currently being used, to collect information about the
solar system and beyond. Look back through the headings and graphics
and plan the two summaries described below.
A history of methods of collecting information about space
Identify methods used over time to collect information about the Universe.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Developments in technology
Trace the developments in technology that have enabled humans to
identify the different components in the night sky.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Now complete Exercises 5.3 and 5.4.
23
Australia’s involvement
with space research
As you read about the history of Australia’s involvement, highlight or
underline information to use in a summary timeline in Exercise 5.6.
You can also look for information in other sources to add to this overview
of Australia’s role in space research.
Australian Aborigines have made detailed naked eye observations of the
sky since earliest times. Australian skies give an excellent view of
celestial objects. Australia has been technologically involved in space
research since the beginning of the ‘Space Age’. At one stage,
Woomera in South Australia was one of the largest spaceports in the
world. Australia’s important contributions to space exploration cannot
be overlooked.
Rocket research
In 1945, immediately after World War II, Britain decided to develop
and test long-range missiles in Central Australia. Using captured
German V-2 rockets, Britain needed to build, launch and track missiles in
an area where they would pose minimal danger to life and property.
An area in central South Australia was chosen in 1946 and named
Woomera Range Prohibited Area. Australia entered the project as an
equal partner and the Anglo-Australian joint project was born.
In 1953, the British Government decided that it needed missiles capable
of hitting targets in other continents. These missiles, called ICBMs
(Inter Continental Ballistic Missiles), were to be capable of carrying
nuclear devices. The two types of rockets built for this purpose were the
Black Knight and the Blue Streak. They were launched and tested at
Woomera from 1958 until 1965.
Australia became the only non-European member of ELDO (European
Launcher Development Organisation) in 1964. This organisation was
established to develop an independent, non-military, European, satellite
launch vehicle. Woomera was also chosen to be the site for these ELDO
launch operations.
24
Space science
Gill Sans Bold
The launch vehicle known as Europa was a three stage rocket, and ten
were launched at Woomera between June 1964 and June 1970. Three of
these launches attempted to place a test satellite into orbit but all three
attempts failed.
Satellites
In November 1967, WRESAT (Weapons Research Establishment
Satellite) was Australia’s first satellite launch, making Australia the
fourth country to launch its own satellite from its own base. Its purpose
included collecting scientific data, including information about the upper
atmosphere. It crashed into the ocean near Ireland in January 1968.
Prospero, Britain’s first independent satellite launch in October 1971,
was the only other satellite to be orbited successfully from the Woomera
range. Prospero was a test satellite, design to check basic systems for
future satellites. It also conducted experiments to detect tiny meteoroids.
Both the WRESAT and Prospero used a Black Arrow launch vehicle,
which had been developed from the Black Knight.
You can access an Internet site with photographs and information about
Woomera at: http://www.lmpc.edu.au/Science
Australia’s second satellite was placed in orbit on 23 January 1970 by
hitching a ride on a US Military Thor-Delta rocket carrying an Itos-1
weather satellite. The Australian satellite basically went on a piggyback
ride, achieving orbit then being ejected by a spring into its
correct position.
This satellite, known as Australis Oscar-5, was no bigger than a shoebox,
ran on two strings of chemical batteries and weighed 17.7 kg. It sent two
continuous signals while orbiting at an altitude of between 1 416 and
1 464 km until the batteries ran out in March 1970.
However, the most amazing thing about this satellite is that it was built
by a few students from the Melbourne University Astronautical Society
as an undergraduate project. Australis Oscar-5 remains silently in orbit
and will continue to do so for several hundred years.
Telecommunications
By the mid 1960s, international communications satellites were being
placed in orbit to link nations separated by oceans. Australia used
satellites from the Intelsat company for its international
telecommunications. The organisation known as OTC (Overseas
Telecommunications Corporation) was responsible for Australia’s
overseas communication via satellite.
25
A ground station build in Carnarvon, Western Australia, tracked
Australia’s first international satellite contact with the United Kingdom
via Intelsat-2.
By 1987, OTC had relocated ground stations closer to capital cities.
They installed stations at Australia’s territory in the Antarctic.
Today, through those ground stations, Intelsat satellites provide 60 to
70% of Australia’s global telephone and television contact.
Because of the vast distances and the need to improve telephone, radio
and TV reception in remote areas, Australia also set up a domestic
communications satellite system. Aussat was established in 1981 for this
purpose and resulted in the launch and deployment of Aussat-1 and
Aussat-2 by the US space shuttle Atlantis in 1985. A third satellite,
Aussat-3, was sent up on an Ariane rocket in 1987.
Australia is one of the world’s largest users of satellite-based systems.
To monitor and manage such a vast continent, Australia’s space scientists
have become world leaders in fields such as remote sensing.
Moon exploration
Besides rocket launches and telecommunications, Australia was involved
in a major milestone of human space exploration. The first TV images
from Apollo 11, of the Moon landing in 1969, were viewed live all over
the world via Australian tracking stations.
The broadcast of Neil Armstrong’s famous words, ‘One small step for
man, one giant leap for mankind,’ came from the Moon to Earth via the
Honeysuckle Creek radio telescope, near Canberra. The dish at Parkes
took over the relay about ten minutes later. NASA decided that Parkes
provided the best pictures so it stayed with its signals for the rest of the
broadcast! Australian radio telescopes were part of the
telecommunications between spacecraft and Earth throughout the
Moon missions.
Australian astronauts
Two Australian born astronauts have made space flights as participants
in American and Soviet space programs. The first was Dr Paul ScullyPower who served aboard the STS 41-G space shuttle mission in 1984.
An oceanographer, Scully-Power, conducted observations of three
quarters of the world’s oceans. During his space mission, Scully-Power
observed structures and currents in the oceans that nobody had
previously recorded.
The second Australian astronaut, Dr Andrew Thomas, is a specialist in
microgravity research. His first spaceflight was on board a 1996
26
Space science
Gill Sans Bold
shuttle mission. In 1998 he spent 130 days on board Mir and in 2001 he
worked on the ISS.
The National Space Program
The National Space Program was established by the CSIRO office of
Space Science and Applications (COSSA), the Australian Space Board
(ASB) and the Australian Space Office (ASO).
In the 1980s, the Australian space industry was given a kick-start
through the development of the Starlab project. Although a funding cut
put an end to Starlab, its development resulted in the establishment of
Auspac Ltd., a space-related industrial and technological company.
It also culminated in the deployment of the Endeavour ultraviolet space
telescope in 1995.
Australian telescopes
Captain James Cook made his first visit to Australia in 1770 after making
observations of Venus passing in front of the Sun. Australia’s first
observatory was established in 1779 by William Dawes close to where
the SE pylon of the Sydney Harbor Bridge is now found. It collected
information about star positions to assist navigation for ships.
The existing Sydney Observatory took over this function in 1859.
World class telescopes have been built throughout Australia because of
our clear, dark skies and position in the Southern Hemisphere.
Australia continues to be a leader in astronomy research because of its
excellent equipment and skilled scientists.
Some examples of telescopes in Australia include:
• The Australia Telescope
This is a group of radio telescopes run by the CSIRO. These include:
– the 64 m Parkes Radio Telescope
This telescope has made many discoveries, particularly
of pulsars. (Over 1 000 have been discovered using the Parkes
Radio Telescope.) The first quasar was identified at Parkes in
1963. It also supported space missions such as the Apollo,
Voyager and Galileo missions and a SETI project. (You’ll learn
more about this in the next section.)
– Mopra
This is a radio telescope near the Siding Spring Observatory at
Coonabarabran.
– the Paul Wild Observatory
This has the ‘Compact Array’, which is a system of six 22 m
radio dishes at Narrabri.
27
•
The Siding Spring Observatory site houses seven optical telescopes,
including:
– the Anglo-Australian Telescope
This telescope has a 3.9 m mirror and is able to observe large
patches of the night sky, larger than any other optical telescope,
by collecting light from 400 target sources.
– the UK Schmidt telescope
This telescope has been involved in a survey of the southern sky.
– the Advanced Technology Telescope
This telescope is operated by the Australian National University
(ANU). It is different from other optical telescopes in that the
whole building in which the telescope is housed turns to follow
a celestial object in the night sky.
•
the Molonglo Observatory
This is a radio telescope outside of Canberra.
SUSI (the Sydney University Stellar Interferometer)
This is an unusual optical telescope that operates in a similar manner
as the array of radio telescopes at Narrabri. It has twelve small
mirrors over a large baseline ranging from 5 m to 640 m to gain as
high a resolution as possible of a selected star. The setup can take
advantage of at least two mirrors with the clarity of the image
increasing as more mirrors are used. How good a telescope system
is it? You could easily see the image of a candle flame on the Moon
using this telescope.
•
•
the Canberra Deep Space Communication Complex
This is a NASA facility at Tidbinbilla near Canberra. It is involved
in the tracking of NASA's crewed missions and robotic space probes
in deep space.
•
the Mt Pleasant Observatory
This is a radio telescope outside of Hobart and operated by the
University of Tasmania.
Did you imagine that there were so many internationally important
observatories in Australia? And this is only some of them!
You can access Internet sites about Australian telescopes and the research
they conduct at: http://www.lmpc.edu.au/Science
Australia’s position in the Southern Hemisphere makes it ideally suited
for further space research and exploration.
28
Space science
Gill Sans Bold
Is anybody out there?
The Universe is an inconceivably vast place. It appears to be devoid of
life because humans from Earth have not detected any evidence of other
kinds of life. However, many people today believe that intelligent life
exists somewhere out there in our galaxy or beyond.
Why is this idea believable?
Our Sun is only one star in a galaxy of at least 100 billion other stars.
Our Milky Way galaxy is only one of at least 100 billion other galaxies,
each made up of billions of stars.
Astronomers are now finding planets around other stars in our galaxy.
This shows that planets may be a natural occurrence in the Universe.
If there is intelligent life on one planet (Earth) orbiting a star (the Sun)
then there must be a very good possibility that another star system would
have life like our own. Many astronomers believe that it is only a matter
of time before they detect communication from intelligent life forms.
The search for extra terrestrial intelligence
The search for extraterrestrial intelligence (SETI) has been considered
for centuries. The current SETI searches have their origins in 1959 when
Guiseppi Cocconi and Philip Morrison published an article in the British
science journal, Nature, in which they pointed out that, in principle, it
would be possible for civilisations to communicate across space using
radio waves.
A young American radio astronomer, Frank Drake, had reached the same
conclusion. In the spring of 1960, he used an 85 foot diameter radio
telescope at Green Bank, West Virginia, to make the first attempt to
detect interstellar radio signals. Drake and his colleagues were looking
for any repeating sequences or patterns that would indicate an
intelligent origin.
29
Many scientists and people in the media feel that SETI is the most
important project in the history of science. This is because it has the
potential for far-reaching and profound implications.
People often wrongly confuse SETI with UFO hunting. Consequently,
they have no concept of the scientific importance of SETI, nor the
extreme care, analysis and evaluation undertaken by the investigating
astronomers and scientists.
How is the search for extraterrestrial intelligence
undertaken?
Scientists search for intelligent signals from space using two methods:
•
radio astronomy
Most investigators are radio astronomers making use of radio
telescopes to collect billions of very weak radio frequencies for signs
of a signal.
•
optical astronomy
To complement the present search, optical astronomers are looking
for messages in the form of pulses of light that may be as short as
one billionth of a second coming from nearby sun-like stars. This
project is called the Optical Search for Extraterrestrial Intelligence
(OSETI).
SETI in Australia
Australian astronomers at the Parkes radio telescope in NSW have been
involved in the search for extra terrestrial intelligence for many years.
As the Parkes telescope scans the heavens conducting research for a
variety of other reasons, the SETI Australia Centre at the University of
Western Sydney is being used to piggyback on the work of Parkes to
collect and tune into millions of radio signals at the same time. It can
scan 58 million frequencies or channels every 1.7 seconds.
Would you like to be a part of the SETI investigation? If you have a
personal computer with Internet capabilities then you can access
SETI@home to learn how to be a SETI investigator. The SETI program
is a special kind of screensaver, which comes into view when your
computer is not being actively used. This program will assist in analysing
the huge volume of data recorded from the Aricebo radio telescope (the
largest radio telescope in the world). Your computer may be the one that
picks up a signal from intelligent life!
30
Space science
Gill Sans Bold
The value of SETI and OSETI
So far, nothing has been collected that can be determined as a signal
from extraterrestrial intelligence. But if humans point telescopes out in
the right direction and listen at the right frequency, we may be able to
pick up messages from other intelligent beings communicating with
each other.
However, we do not know which is the best direction. With the billions
of stars just in our galaxy at such enormous distances from one another,
you can appreciate how difficult it is to pick up any possible message.
1
Alpha Centauri is the brighter star of the two Pointers to the
Southern Cross constellation. It is a very tiny distance of 4.3 light
years away or about 40 trillion kilometres. This would mean that
radio messages (or light messages) would take 4.3 years to reach
there and another 4.3 years to be returned if intelligent life there
could respond immediately, a total of 8.6 years.
What problems would intelligent civilisations have sending
messages to each other if their star systems are hundreds of light
years away?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
What benefits would be achieved by contact with intelligent life
elsewhere in the Universe?
Humans would gain access to the scientific, technological, biological as
well as philosophical knowledge that exists in other intelligent
civilisations. This knowledge can only enrich our own quality of life,
particularly if the civilisations are much older than our own.
You must remember that our civilisation is really only a very young one.
Any civilisation that humans encounter will be much more sophisticated
because their communications would have left their world a very long
time ago. We have only been communicating using radio waves for
about 100 years, since the invention of the radio.
2
The first intentional human radio message to other intelligent life
was sent into space in 1974. How far has this message travelled?
_____________________________________________________
31
This is your opportunity to claim that the time you have spent watching
television was valuable! Complete the tasks below using ideas from
cartoon and space shows, books, comics and magazines or make up your
own ideas!
3
Suggest three improvements to human life on Earth if we could tap
into the knowledge of other civilisations in the cosmos.
Write your answers under the following headings:
a) scientific
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
b) technological
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
c) biological
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
__________________________________________________
4
What problems do you think might arise due to contact with forms of
intelligent life from other solar systems?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
32
Space science
Gill Sans Bold
The SETI and OSETI projects have not been a waste, even if intelligent
life is never detected. This is because of the improvements in space
research that have occurred because of these projects. For example,
the SETI and OSETI projects have encouraged:
•
the development of the very best technology, particularly in radio
receiving systems
•
the cooperation of scientists and engineers committed to excellence
in their quest
•
young students to pursue science.
Use information from throughout this section, including your own answers,
to complete Exercise 5.5.
33
34
Space science
Gill Sans Bold
Suggested answers
Demonstrating a convex, or converging, lens
The drop of water makes the letters look bigger. It magnifies them.
Position, position, position
Light from space does not have to travel through as much of the
atmosphere as air is most dense close to Earth’s surface. The more
particles are present – both normal air particles and pieces of dust and
pollution – the more the incoming light will be scattered. Scattering
causes images of objects in space to be fuzzy.
Beyond light observations
1
a) The Hubble Space Telescope collects visible light, infrared
waves and ultraviolet waves.
b) Some celestial objects that have been studied with the Hubble
telescope include planets, comets, nebulae, galaxies and stars.
2
Electromagnetic radiation that would be more effectively collected
by a space-based receiver include: gamma waves, X-rays, infrared
waves and most microwaves.
3
Electromagnetic waves that penetrate Earth’s atmosphere are:
some low energy ultraviolet (UV), visible light, some low energy
microwaves and radio waves.
35
How does a radio dish work?
parallel radio waves
from space
focal point
parallel radio waves
from space
reflected
radio waves
dish
VLBA
The VLBA collects radio waves to make pictures of objects throughout
the Universe, including quasars and supernovae.
HALCA
HALCA and the GBS collect radio waves to make detailed pictures of
objects throughout the Universe.
Some space probe programs
Space probes can collect lots more information about objects in the
Solar System because they can actually go there! (There are still many
objects in the Universe too far away to be reached by space probes.)
Mir
Here are the main points:
36
•
begun in 1986, completed 1997, destroyed 2001
•
Russian space station, built in space
•
used by astronauts from 12 countries over 12 years
•
thousands of scientific investigations performed.
Space science
Gill Sans Bold
Name: _________________________________
Exercise 5.1
a)
Draw lines to represent how radio waves are focused on the dish in
the diagram of the Parkes telescope below. Add appropriate labels.
b) Outline one way in which information is transmitted between Earth
and a space station.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
37
Exercise 5.2
Gather and analyse information about the Voyagers 1 and 2 probes.
a)
Present an overview (a brief description) of the roles of Voyagers 1
and 2 space probes.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
b) How has our understanding of the solar system and beyond been
furthered (or increased) due to exploration by these space probes?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Exercise 5.3
List methods used over time to collect information about our solar
system and beyond.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
38
Space science
Gill Sans Bold
Exercise 5.4
Trace the developments in technology that have enabled humans to
identify the different components in the night sky. (Present your
information in the way that you think expresses it most clearly.
For example, you could draw a flow chart or concept map, construct
a table, write a newspaper article or use another presentation method.)
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Exercise 5.5
Discuss the value of Search for Extraterrestrial Intelligence (SETI) and
Optical Search for Extraterrestrial Intelligence (OSETI) projects to
identify life and advanced civilisations in the Universe.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
39
Exercise 5.6
In the space below, draw a timeline to trace Australia’s involvement in
space exploration. (Your timeline does not have to be to scale.)
40
Space science
Gill Sans Bold
Exercise 5.7
Use information and ideas you have acquired from studying this module
for this exercise. (You can add extra information too, if you wish.)
Discuss requirements that would be necessary to sustain human life for
months or even years on a space station.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
41
Gill Sans Bold
Senior Science
HSC Course
Stage 6
Space science
Part 6: Space technology and society
2
0
0
I
2
r
be S
o
t
c NT
O
ng DM E
i
t
ra E N
o
rp A M
o
nc
Gill Sans Bold
Contents
Introduction ............................................................................... 2
Who wants to wear a spacesuit?............................................... 3
How do EVA spacesuits protect astronauts?......................................3
How do spacesuits meet astronauts’ needs? .....................................6
What are spacesuits made of? ............................................................7
Spin-offs from space programs ................................................. 9
What’s the value?...............................................................................10
The impact of space research on society ................................ 12
Additional resources................................................................ 13
Exercises – Part 6 ................................................................... 19
1
Introduction
How has space research affected society? This is the main idea that you
will investigate in Part 6. You can use a potato, a plastic straw, two long
balloons and three large rubber bands in activities in this part.
•
identify some of the materials used in spacesuits and relate their
properties to the conditions that astronauts may experience
•
identify many of the spin-offs from space programs that have
impacted on consumers including
–
life support systems
–
pacemakers
–
thermal blankets
–
ceramics
–
miniaturisation of computer systems, calculators, mobile phones
–
composite materials from carbon fibres
–
foodstuffs
–
packaging
and compare the original use of the material to its current use in society.
•
gather and process information from secondary sources to describe
precautions necessary to protect against radiation in space
•
gather and analyse information from secondary sources to assess the
impact that spin-offs from space research have had on society and
debate the value in continuing the space program.
2
Space science
Gill Sans Bold
Who wants to wear
a spacesuit?
A spacesuit is a good example of a space technology that has had
an influence on normal society. You’ll find out why as you learn about
what spacesuits do and why they work.
Whereas a spacesuit was worn during a whole mission in the early
space program, they are now only required when the astronaut undergoes
lift-off and re-entry, and while performing an extravehicular activity
(EVA) outside the space shuttle or space station.
The spacesuits worn during lift-off and re-entry are different from those
worn during EVAs. During lift-off and re-entry, astronauts are protected
within the spacecraft. The EVA spacesuit is a completely self-contained
unit providing all the requirements for life-support while protecting the
astronaut from the extreme hazards of the space environment.
How do EVA spacesuits protect
astronauts?
The materials and properties of an EVA spacesuit protect the astronaut
from the adverse conditions experienced in space. Here are some ways
that a spacesuit provides protection and meets an astronaut’s needs.
Protection against a near vacuum
You learnt in Part 1 that space has fewer particles per cubic metre than
the best vacuum ever created on Earth. So the air pressure in space is
extremely low. If an astronaut was exposed to such low pressure, gas in
the lungs would escape and blood flowing through the lungs would lose
oxygen. The astronaut experiences dizziness and blurred vision, then
passes out and dies within minutes.
The effect of low pressure on an astronaut’s blood can be demonstrated
when you remove the cap from a bottle of carbonated soft drink.
3
Observe what suddenly appears in the fluid as the cap is removed.
What do you see? The bottle cap is like Earth's atmosphere, maintaining
pressure and keeping the gas dissolved in the liquid drink.
The gas pressure maintained in an EVA spacesuit is about 30% of
atmospheric gas pressure on Earth. The gas in the spacesuit is 100%
oxygen (compared with 20% on Earth) so that heavy breathing is not
required to keep the body, especially the brain, supplied with oxygen.
Using a lower gas pressure, 30% of that on Earth, makes the spacesuit
much more flexible for movement. You probably appreciate this from
playing with balloons. A balloon that is filled with air is very rigid
whereas one that is only partly filled with air is much easier to flex.
Protection against extremes of temperature
The astronaut in space is also exposed to an extreme range of
temperatures in the external environment of space. When facing the Sun,
the astronaut’s unprotected body could heat to about 110°C while the
rear of the body, which is not in sunshine, could cool to –110°C or lower.
The outer covering of the spacesuit helps to prevent heat being absorbed
or lost due to the surrounding conditions of space.
It is not only the external conditions that need to be considered.
Working for many hours with a thick spacesuit around you will cause
you to become very hot. Temperature control of the body is achieved by
wearing a special water-cooled garment under the outer layer. A suit
pump circulates water through the suit so that excess body heat can
be absorbed.
Protection against radiation
The outer covering of the spacesuit also helps to protect the astronaut
from radiation from the Sun. This radiation can produce tissue damage,
chromosome changes or even death. The visor of the helmet reduces the
glare of the Sun and restricts absorption of UV and infrared energy.
Finding out more
What precautions are needed to protect against radiation in space?
Carry out your own research to find information to answer this question.
You will also find information in the ‘Additional resources’ section at
the end of this part.
Use your information to complete Exercise 6.1.
4
Space science
Gill Sans Bold
Protection against micrometeoroids
Micrometeoroids are small pieces of rock in space. They are usually
left behind by comets and, like other objects in space, micrometeoroids
travel faster than a bullet, at up to 80 km/s.
Micrometeoroids constantly bombard the space shuttle and other
spacecraft. The larger the bit of space debris, the more damage it can
cause on collision. Even micrometeoroids, about the size of a grain of
sand, can cause damage to an under-protected space walker.
Spacesuits have multi - layers of material designed to disintegrate
penetrating micrometeoroids.
Here is an activity that you can perform to give you a better idea of the
kind of damage micrometeoroids can do.
Why are micrometeoroids a hazard to a space walker?
You will need a raw potato (or an apple) and a plastic straw for this activity.
Hold the raw potato securely by closing one hand around (not
underneath) the potato. Place your thumb over the end of the straw and
sharply stab down into the potato. The fast-moving straw represents a
fast-moving micrometeoroid.
Did the straw go through the potato? __________________________
Does a slow-moving micrometeoroid cause the same damage?
Hold the potato while you use a slower motion with the straw to stab the
potato. What happens?
_________________________________________________________
5
How do spacesuits meet astronauts’
needs?
A spacesuit can meet the needs of an astronaut for about nine hours.
Here are some typical features of an EVA spacesuit. Such a spacesuit
could have 18 parts, 14 layers and weigh 114 kg on the Earth.
TV camera
lights
Life support system
• oxygen tanks
• water
• contaminant control
in-suit drink bag
temperature control
gloves
urine collection
device
inner cooling and
ventilation garment
A simplified diagram of a typical spacesuit as used by astronauts.
Make a list of ways that this spacesuit meets the needs of an astronaut
during an extravehicular activity.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
6
Space science
Gill Sans Bold
What are spacesuits made of?
The spacesuit is made up of layers, mostly of plastic. Materials used are
selected to prevent fungus or bacterial growth. Underline or highlight the
different materials in the layers as you read the following information.
•
The two innermost layers make up the liquid cooling and ventilation
garment. This is made of spandex fabric, and plastic tubing that carries
water. These materials address the need for cooling the body.
•
Next is the pressure bladder layer that maintains the required air
pressure upon the body. It is made of a polyurethane-coated nylon
and a cover layer of pressure-restraining Dacron.
•
Then there are several layers of aluminised Mylar, covered with
Dacron, topped with a layer of Gortex, Nomex and Kevlar. These
layers of the spacesuit protect against micrometeoroids. They also
slow heat loss from the body to the space surroundings and reduce
absorption of heat from the Sun.
•
The helmet is made with a polycarbonate shell, the visor of which is
very clear for good vision but protects the face from UV and infrared
radiation.
Now reread the information. This time, use a pencil to circle the space
conditions that the materials are able to protect astronauts against.
Some fabrics and materials
Here is a brief description of some of the properties and uses of fabrics
and materials used in spacesuit construction. These materials are also
widely used in society, especially for clothing and furnishings.
Dacron®
A polyester fibre, used as stuffing in cushions
and furniture and mixed with other fibres to
form fibre blends. Resists matting and mildew,
strong and resilient while remaining soft,
non-absorbent
Gortex®
A fabric that is water resistant, readily allows
airflow and passage of perspiration (‘breathes’)
and is light weight
Kevlar®
A member of the nylon family of polymers.
Forms very strong fibres that can be used in
bulletproof vests, puncture-resistant bicycle
tyres, fireproof clothing. Fibres are resistant to
solvents and unaffected by air up to 400°C
7
Mylar®
A polyester that forms a film. Used as an
unreactive lining for other products
Nomex®
A member of the nylon family of polymers.
A fireproof material
spandex
A copolymer, combining the properties of two
materials: fibres of rigid polyurethane and
elastomeric (stretchy) polyoxyethylene.
This forms a fibre that stretches. Its trade name
is Lycra®
polyurethane
A lightweight polymer that can be used in a
wide range of products, including foam, paint,
fibres and adhesives
Use the names of materials and the space conditions that you have
identified above to complete the table in Exercise 6.2.
You may have predicted that a suit with so many layers could be
difficult to wear! Here is an activity that you can do to investigate how
an inflated spacesuit restricts movement.
Simulation of a spacesuit
You will need two long balloons and three large rubber bands for this activity.
What happens to the ability to bend a long balloon if rubber bands are
placed over the balloon as it is being inflated?
Blow up one balloon as normal. Inflate the second balloon slowly so that
you can slide the three rubber bands at intervals along the balloon.
Try to bend both balloons. Which one is easier to bend?
_________________________________________________________
_________________________________________________________
The rubber bands on a balloon act like joints, making it easier to bend
and move the balloon. The same principle is applied to the construction
of a spacesuit. Rings placed in the right positions help form joints to
allow easier movement while wearing the spacesuit.
Look at the hose of a vacuum cleaner. You will notice that it also has built-in
ribs or joints that allow the hose to be easily bent.
8
Space science
Gill Sans Bold
Spin-offs from space programs
Many of the conveniences that you use in your everyday life, from the
kinds of things you wear to a lot of the food products you eat, are due to
the space program. The technology that has put humans into space,
allowed them to walk on the Moon and enabled them to live on-board the
space shuttle and space stations, has found its way into everyday life.
These secondary uses of space technology are called spin-offs.
They continue to enhance our life on Earth. There are at least 30 000
secondary applications of space technology providing daily benefits in
hospitals, offices and homes. What are some of these spin-offs?
Look back at the diagram and photograph of a spacesuit. What things from
these graphics do you think have affected how people live?
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Look at the ideas in the suggested answers.
9
What’s the value?
Your task for the rest of this part is to find out about spin-offs of space
research and to assess how these have (or haven’t) benefited society.
You will find examples in a variety of resources, including books,
magazines and CD-ROMs. You can also access spin-offs webpages from
http://www.lmpc.edu.au/Science or by using an Internet search engine.
You can use the table below to organise information that you collect.
(The blank rows are for any extra spin-offs that you find.)
Original use in
space research
Spin-off
Current use in
wider society
life support systems
pacemakers
thermal blankets
ceramics
small size of computer
systems, calculators,
mobile phones
composite materials
from carbon fibres
continued on the next page
10
Space science
Gill Sans Bold
Original use in
space research
Spin-off
Current use in
wider society
foodstuffs
packaging
11
The impact of space
research on society
Using the information about spin-offs from the space program that you
have analysed, discuss the impact space research has made on society
and debate its value to society.
If you can, discuss your ideas with another student or with a group
of friends or family. You can do this by meeting together or by email
or telephone. Compile the ideas you discuss in the table following.
What is the value of space research for society?
A plus for society
A minus for society
Now complete Exercise 6.3.
Have you enjoyed your study of space science? Hopefully, you now have a
better understanding that there are enormous benefits (and some problems)
for people on Earth that can come from exploring space.
So if you had to decide how to spend some of Australia’s wealth, would
you set aside money for more space research?
12
Space science
Gill Sans Bold
Additional resources
Radiation in space
Away from the protection of Earth’s atmosphere, space travellers are
exposed to very dangerous radiation.
Every star, including our Sun, produces electromagnetic radiation such as
visible light and infrared, or heat. These types of radiation are beneficial
to life on Earth.
But other high-energy electromagnetic waves, also produced by stars,
are very dangerous. Examples are gamma rays, X-rays and ultraviolet
radiation. These types of radiation have sufficient energy to damage
cells and break DNA, leading to cancer and genetic changes.
Gamma rays and X-rays are prevented from reaching Earth by
our atmosphere.
Charged particles
A constant flow of charged particles, mostly electrons, stream from the
Sun in what is known as the solar wind. Solar flares intensify the
solar wind.
A typical solar flare of the Sun stretches out to some millions of
kilometres of space.
Extremely high levels of charged particles and cosmic radiation are
usually associated with these solar flares.
The Earth's magnetic field is highly protective against charged particles
for people on Earth, as well as for astronauts on a space station and space
shuttle. Without this protection, these high-energy charged particles
would cause cell and DNA damage similar to high-energy
electromagnetic radiation.
13
When the charged particles of the solar wind hit Earth's magnetic shield,
they spiral towards the north and south poles. The resulting collision
with the atmosphere produces the auroras.
The space station and the space shuttle are shielded from these
dangerous particles by remaining where the Earth's magnetic field is
strongly protective (orbit altitude < 550 km) and not venturing too close
to the poles. A weak spot in the Earth’s magnetic field above the
South Atlantic is also avoided.
Cosmic radiation, or cosmic rays
Cosmic rays are also a problem for space travellers. They are invisible,
high-energy particles (not electromagnetic radiation), that constantly
bombard Earth from all directions. The source of most cosmic rays
(mainly high-speed protons) is still debated but they may be produced in
supernova explosions or even galaxy collisions.
Much of the cosmic radiation that enters the atmosphere loses energy and
does not reach the Earth’s surface. Jet aircrew are exposed to much more
cosmic radiation and this is one reason why pilots and aircraft attendants
do not spend as many hours at work as workers on the ground.
Cosmic rays are one of the main health dangers that will face astronauts
on longer space flights, such as a trip to Mars. They can be responsible
for cancers, brain and nerve damage, and changes to DNA.
Cosmic rays can pass through the walls and windows of the space station
and shuttle, eventually passing through the bodies of astronauts.
Nothing can prevent the entry of cosmic rays. If they enter the eyes of an
astronaut, the astronaut will experience flashes of lights within the eye.
Ultraviolet radiation
Ultraviolet radiation is a kind of electromagnetic radiation. It is not
stopped by Earth's magnetic field. The space station has windows that
act like sunglasses to block UV radiation that comes from the Sun.
If an astronaut were to look out of an uncovered window of the space
shuttle towards the Sun, then he/she would become extremely sunburned
in less than a minute as well as having the retinas in the eye burnt,
causing blindness. Shades are placed on windows to minimise this kind
of radiation exposure.
14
Space science
Gill Sans Bold
Unpredictable risks
Astronauts in space experience about 100 times greater exposure to
radiation energy (solar electromagnetic, solar charged particles, cosmic)
than when on Earth. If the space shuttle or space station is unexpectedly
exposed to a solar flare then the astronauts inside may experience a
year’s dose of radiation in one hit.
If an astronaut is exposed without warning to a sudden, very strong dose
that is at least twice a normal yearly dose while undertaking a space
walk, he/she may be in danger of death because the spacesuit is not very
protective for this amount of radiation. If he/she is ‘lucky’, the outcome
of the high exposure might only be a cancer, developed later in life.
If a very large solar flare occurs, which delivers a dose equivalent to
10 times a yearly amount of exposure, astronauts would have to abandon
their mission. If they cannot be warned in time about this danger then
exposure may be fatal to all of those onboard. American astronauts and
Russian cosmonauts have been very fortunate so far with regards to this
kind of danger.
Some precautions
Radiation can produce tissue damage, chromosome change or even
death. Preflight requirements for any mission must include:
•
a theoretical projection (estimation) of the radiation dosage for all
astronauts involved
•
a review of the radiation exposure history of each crew member
(Damage is cumulative. This means that it adds together, so more
and more exposure to radiation means more and more risk of health
damage.)
•
an assessment of the probability of solar flare activity during the
time frame of the mission.
The radiation dose absorbed by an astronaut in a space shuttle flight
ranges between 0.05 and 0.07 rem*, which is well below the
recommended exposure limit of 5 rem in a year.
*
The rem is the unit used to measure radiation absorbed by a human.
For long-distance travel to places like Mars, special shielding against
constant exposure to radiation will have to be included in the
construction of the spacecraft. Development of suitable shielding and a
better understanding of health risks for lengthy space travel are still at a
research stage.
15
16
Space science
Gill Sans Bold
Suggested answers
How do spacesuits meet astronauts’ needs?
Here are some examples from the diagram:
•
TV camera sends pictures of what the astronaut sees to others so that
they can provide advice or record the information for other uses
•
lights provide light for clear vision
•
life support system provides oxygen for breathing, removes wastes
(contaminants, such as carbon dioxide) and provides water (to
humidify air)
•
drink bag provides drinking fluid to prevent dehydration
•
temperature control allows astronaut to change the temperature
inside the suit
•
gloves protect hands while enabling the astronaut to complete tasks
•
urine collection device means that the astronaut can work outside the
STS or ISS without having to re-enter it to urinate
•
cooling and ventilation garment removes sweat and heat made by the
astronaut during activity so that he/she does not overheat.
Spin-offs from space programs
Some ideas might include: video cameras; head-mounted equipment
(such as cameras and lights used by dentists); life support systems in
hospitals; sealed clothing for people who work with toxic or infectious
substances; toys; even some clothing fashions!
17
18
Space science
Gill Sans Bold
Name: _________________________________
Exercise 6.1
Read the information on radiation in the Additional Resources section.
Describe precautions necessary to protect against radiation in space.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
19
Exercise 6.2
Complete the table below to show how the properties of materials used in
spacesuits relate to conditions experienced in space.
eg.
Space suit material
Conditions in space
spandex fabric
able to draw water away
from skin; transfer heat
heat and sweat inside
suit caused by an
astronaut’s activities
plastic tubing
carrying water
polyurethane-coated
nylon and Dacron
aluminised Mylar,
Dacron, Gortex, Nomex
and Kevlar
Exercise 6.3
Use evidence from this module to support the following arguments.
a)
The space program should be continued.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
b) The space program should be stopped.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
20
Space science
Student evaluation
of the module
Name: _______________________
Location: _____________________
We need your input! Can you please complete this short evaluation to
provide us with information about this module. This information will
help us to improve the design of these materials for future publications.
1
Did you find the information in the module clear and easy to
understand?
_____________________________________________________
2
What did you most like learning about? Why?
_____________________________________________________
_____________________________________________________
3
Which sort of learning activity did you enjoy the most? Why?
_____________________________________________________
_____________________________________________________
4
Did you complete the module within 30 hours? (Please indicate the
approximate length of time spent on the module.)
_____________________________________________________
_____________________________________________________
5
Do you have access to the appropriate resources? (eg. a computer,
the internet, scientific equipment, chemicals, people that can provide
information and help with understanding science)
_____________________________________________________
_____________________________________________________
Please return this information to your teacher, who will pass it along to
the materials developers at OTEN – DE.
SSCHSC43172 Space science
Learning Materials Production
Open Training and Education Network – Distance Education
NSW Department of Education and Training

Space science - NSW Department of Education

Transcription

Similar documents

just steps away - Arts District Hyattsville

with an Astronaut - Pearson SuccessNet

Furniture Market Fall 2016 Flyer

Redesign Plan - Vanessa Runco

DOCUMENT REVISED MAY 8 Shuttle service A shuttle service is

Some Concluding Remarks

Downtown and Shuttle Map

Bus Etiquette

Parking Services at UW Oshkosh

eng - dianabalzarini