TITAN A MOON WITH AN ATMOSPHERE

TITAN
A MOON WITH AN ATMOSPHERE
Ashley Gilliam
Earth 450 – Satellites of Jupiter and Saturn
4/29/13
SATURN HAS > 60 SATELLITES, WHY TITAN?
Is the only satellite with a dense atmosphere
Has a nitrogen-rich atmosphere resembles
Earth’s
Is the only world besides Earth with a liquid
on its surface
•  Possible habitable world
Based on its size…
Titan " a planet in its o# $ght!
R = 6371 km
R = 2576 km
R = 1737 km
Ch$%iaan Huy&ns (1629-1695) DISCOVERY OF TITAN
Around 1650, Huygens began building
telescopes with his brother Constantijn
On March 25, 1655 Huygens discovered Titan
in an attempt to study Saturn’s rings
Named the moon Saturni Luna (“Saturns
Moon”)
Not properly named until the mid-1800’s
THE DISCOVERY OF TITAN’S ATMOSPHERE
Not much more was learned about
Titan until the early 20th century
In 1903, Catalan astronomer José
Comas Solà claimed to have
observed limb darkening on Titan,
which requires the presence of an
atmosphere
Gerard P. Kuiper (1905-1973)
José Comas Solà (1868-1937)
This was confirmed by Gerard Kuiper
in 1944
Image Credit: Ralph Lorenz
M"sions to Titan
Voyager 1
Launched September 5, 1977
Pioneer 11
Launched April 6, 1973
Images: NASA
Cassini-Huygens
Launched October 15, 1997
Pioneer 11
Could not penetrate Titan’s Atmosphere!
Image Credit: NASA
Voya&r 1
Image Credit: NASA
Voya&r 1
What did we learn about the Atmosphere?
•  Composition (N2, CH4, & H2)
•  Variation with latitude (homogeneously
mixed)
•  Temperature profile
•  Pressure profile
Mesosphere
Stratosphere
Troposphere
Image Credit: Fulchignoni, et al., 2005
Image Credit: Conway et al. 2003
What is the main similarity between Earth’s atmosphere and Titan’s?
From Conway et al. 2003
Credit: C. P. McKay
M =P
g
Titan: P = 1.5 bar = 1.5×105 Pa g = 1.35 m s-­‐2 P = atmospheric pressure g = gravita2onal accelera2on 1 Pa = 1
N
kg
=
1
m2
m ! s2
M = 1.1 × 105 kg m-­‐2 The column mass is greater on Titan. More substan2al atmosphere. Earth: P = 1 bar = 1×105 Pa g = 9.78 m s-­‐2 M = 1.0 × 104 kg m-­‐2 Cassini-Huy&ns
RADAR-SAR instrument was able to penetrate Titan’s thick veil of haze
Pre-Cassini
Cassini
Image Credit: NASA
Image Credit: NASA
• 
(e Huy&ns Probe
Goals of the mission:
•  Collect aerosols for chemical analysis
•  Make spectral measurements and take pictures of Titan’s surface and atmosphere
•  Measure wind speeds
•  Identify composition of the atmosphere
•  Measure the physical properties of the atmosphere
•  Determine the physical state, topography, and composition of the surface
(e Huy&ns Probe
The Huygens probe separated from the Cassini orbiter on December 25, 2004
Took 148 minutes to descend through the atmosphere
Was prepared to touch down on
land or liquid
Based on the pictures taken by
Cassini 1,200 km away, the
landing site appeared to resemble
a shoreline
HUYGENS LANDING SITE
Landed January 14, 2005 at 10.2°S,
192.4°W
Discovered small “rocks”, possibly made
of water ice, at the landing site.
Fluvial activity (methane?)
Images taken during descent showed no
open areas of liquid, but indicated liquid
had once flowed
Titan
Image Credit: NASA
Earth
POSSIBLE SHORELINE
100 km
LAKES ON TITAN
Image Credit: NASA
Titan: Ligeia Mare
Earth: Lake Superior
Image Credit: William Hubbard, UA LPL
AN ALIEN ENVIRONMENT
TITAN
EARTH
Surface Liquid:
Liquid methane & ethane
Water
Surface:
Ice
Rock
Surface Composition:
Hydrocarbons
Dirt
Titan’s South Pole Clouds over a five hour period
Credit: C. P. McKay
Credit: C. P. McKay
COMPARING TITAN AND EARTH
Property
Titan
Earth
Gravity
1/7
1
Pressure
1.5 atm
1 atm
Atmosphere
N2, CH4
N2, O2 ,CO2
Clouds & Rain
CH4, C2H6
H2O
Greenhouse
N2, CH4, H2
CO2, H2O
Temperature
-180oC
+15oC
Rotation
16 days
1 day
Solar Orbit
30 years
1 year
Habitability of Titan
Titan = 0.64
Mars = 0.59
Gliese 581d = 0.43
Credit: Popular Science
Future M"sions
Aerial Vehicle for In-Situ and Airborne
Titan Reconnaissance (AVIATR)
Titan Saturn System Mission (TSSM)
Titan Mare Explorer (TiME)