SPICA White Paper

SPICA @ MPE
Mission Overview, Science Potential, and Prospective
Contribution and Role of MPE
A White Paper for Discussion
December 5, 2011
Authors:
A. Poglitsch
E. van Dishoeck
W. Raab
E. Sturm
D. Lutz
H. Feuchtgruber
1
ISSUE
DATE
SECTION /
PARAGRAPH
AFFECTED
REASON/INITIATION
DOCUMENTS/REMARKS
0.1
5 Dec 2011
All
Initial issue for internal revision
2
Contents
1. Scope................................................................................................................................................................... 4 1.1 Further reading .......................................................................................................................................... 4 1.2 Acronyms .................................................................................................................................................. 4 2. Mission Overview .............................................................................................................................................. 5 2.1 Spica Satellite ........................................................................................................................................... 5 2.2 SAFARI .................................................................................................................................................... 9 2.2.1 The Instrument .......................................................................................................................................... 9 2.2.2 SAFARI Consortium Organisation ......................................................................................................... 10 2.3 Science Management / Observing Time Allocation .............................................................................. 11 3. Science Potentials ............................................................................................................................................. 13 3.1 Science Cases .......................................................................................................................................... 13 3.1.1 Star and planet formation and evolution ........................................................................................... 13 3.1.2 Exoplanets .......................................................................................................................................... 17 3.1.3 Galaxy evolution ................................................................................................................................ 19 4. Potential MPE Contributions ........................................................................................................................... 24 4.1 Involvement up to now ................................................................................................................................... 24 4.2 Suggestions for future contributions .............................................................................................................. 24 4.2.1 Participation in the Instrument Control Center (ICC)...................................................................... 25 4.2.2 Detector System Tests ........................................................................................................................ 26 4.2.3 SQUID Array and Cryogenic Preamplifiers Development ............................................................... 28 4.2.4 Filter Wheel Development ................................................................................................................. 29 4.2.5 Summary ............................................................................................................................................. 31 3
1. Scope
This is a white paper to provide a basis for discussions within the Infrared Group at MPE and
amongst the board of MPE directors. It gives a summary of the SPICA mission, a description
and assessment of capabilities and science cases that are of potential interest to the infrared
group in particular and to MPE in general, and suggests possible MPE contributions to the
mission. The science cases as such are only briefly described here, for the sake of brevity and
only to suggest the science topics for discussion. For detailed descriptions of these (and
further) science cases we refer to the Yellow Book (see the section “further reading” below).
1.1 Furtherreading
-
-
[RD1] Science Case part of The SPICA Assessment Study Report (aka “Yellow
Book”)
[RD2] FAR-IR/SUBMILLIMETER SPECTROSCOPIC COSMOLOGICAL SURVEYS:
PREDICTIONS OF INFRARED LINE LUMINOSITY FUNCTIONS FOR z<4
GALAXIES, Spinoglio et al. 2011, arXiv1110.4817
[RD3] Some experiments related to Safari spectroscopic surveys (a Note by Dieter
Lutz and Javier Gracia Carpio)
1.2 Acronyms
AIV
DPU
EGSE
EM
EMC
ESA
FM
FPA
FS
FTE
ICC
ILT
JAXA
PI
PM
PSF
QM
SAFARI
SRON
Assembly, Integration and Verification
Digital Processing Unit
Electronic Ground Support Equipment
Engineering Model
Electromagnetic Compatibility
European Space Agency
Flight Module
Focal Plane Assembly
Flight Spare
Full Time Equivalent
Instrument Control Centre
Instrument Level Test
Japan Aerospace Exploration Agency
Principal Investigator
Project Manager
Point Spread Function
Qualification Model
S(PIC)A FAR-infrared Instrument
Space Research Organisation of the Netherlands
4
2. Mission Overview
The SPICA (Space Infrared telescope for Cosmology and Astrophysics) is a JAXA-led
mission to which ESA has been invited to become a partner, by providing the cryogenic
telescope assembly and contributing to the ground segment. An additional European
contribution is the nationally funded SAFARI Focal Plane Instrument. After its selection as a
candidate mission for the Cosmic Vision 2015-2025 (as an M-class “Mission of
Opportunity”), the proposed European contribution to SPICA is undergoing the corresponding
Assessment Study phase. In Japan, SPICA is part of the JAXA and is in the final phase of in
“Preproject” phase, which roughly corresponds to ESA’s “Phase A”, which will extend until
the end of this year. The mission has passed its “System Requirement Review” this
September, with the strong recommendation to introduce a “Risk Mitigation Phase”. This
activity has been split into two parts. Part 1 (September to December 2011) is being done by
analysis, mostly. Part 2 will involve industrial partners, which shall be selected in the first
quarter of 2012, and will be roughly equivalent to a Phase B1. ESA is considering a proper
implementation of a “Phase B1” according to their definition at that time (early 2012) as a
decision point regarding their further support of SPICA. Part 2 of this “Risk Mitigation” /
Phase B1 exercise will be concluded with a review in the fall of 2012, followed by a Request
for Proposals for phases B2/C/D. The final kick-off is planned for early-mid 2013.
2.1 Spica Satellite
SPICA is planned at JAXA as a nominal three year mission (goal 5 years) orbiting at L2 that
will be launched on the H-IIA 204 in 2022 from the JAXA Tanegashima Space Centre. High
photometric sensitivity observations are made possible with a 3.2 m telescope which is
actively cooled down to < 6 K, in order to effectively eliminate the non-astronomical photon
noise. The large aperture, monolithic mirror, with the requirement of diffraction limited
performance at 5μm, enables high spatial resolution and an adequately controlled point spread
function.
SPICA (like Herschel or Planck) will orbit around the Lagrangian point L2, located
approximately at 1.5 million km from the Earth, in the anti-sun direction. It is estimated that
the mission requires a minimum of five hours ground contact per day. The scientific outcome
would be greatly enhanced by an increase in the telemetry budget, which could be achieved
through the provision by ESA of a ground station in Europe. The contribution of this
additional ground station is also being evaluated in the ESA Assessment Study.
The main contribution by ESA is the telescope, which is largely based on the development
done for the Herschel telescope. Two industrial studies (Astrium and Thales) have been
carried out under ESA contracts; both have demonstrated the feasibility of the required
telescope specifications.
5
Figure 1: Main elementss and constrain
nts of the SPICA
A satellite. Lefft: to enable thee required low telescope tempperature
mal shielding and
a surface pro
operties of all elements
e
are a major
m
design driver.
d
The teleescope uses
and strayllight level, therm
Herschel h
heritage but wiith a wavefrontt error reduced
d by at least onee order of magn
nitude. Use of the H-IIA rath
her than
the originaally foreseen H-IIB
H
launcherr (for cost reaso
ons) has led to a reduction of the telescope diameter
d
from 3.5m
3
to
3.2m. Twoo competing in
ndustry studies have demonstrrated the feasibbility of this teleescope system.
An impportant com
mponent off the satelllite conceppt is a seet of mechhanical cooolers for
temperaatures down
n to ~1K. ISAS
I
has been
b
workinng on such coolers forr many yearrs; while
the 4K
K coolers can
c
be connsidered fuully demonsstrated, thee 1K cooleers are stilll under
developpment, from
m a breadboard model to a space-qualified sy
ystem. Thee biggest isssue with
the coollers is their limited coooling powerr; in particuular, they caannot cope with
w heat puulses but
this is a
require a steady loaad. For anyy instrumennt with, e.g., intermittenntly used mechanisms
m
design ddriver. Alsso, for the full
f set of studied
s
focaal plane insstrument, th
he resultingg cooling
power per
p instrumeent is unreallistically low
w.
N
Noise
source
Coolerr base plate
2ST cooler
c
×4
4K JT
T cooler ×2
1K JT
T cooler ×2
2 sta
age stirling cycle
e cooler
4K /1
1K JT Cooler com
mpressor
Drivving frequency 15H
Hz
Drivving frequency / 55
5+38Hz(TBD)
Config: compressor/d
desupressor Con
nfig: compressor (2
2 or 3)
Acctive balance
Op
pposed positioning noise
(Noise attenuation sysstem)
su
uppression
Joule Thomps
son system
Driving freque
ency 0.05Hz
Noise path
Figure 2: The mechanicaal cooler system
m is one of the innovative devvelopments for SPICA.
S
Whilee they should prrovide a
ng power is a design
d
driver foor cold mechaniisms (FTS scan
nner) and
lifetime off 5 years, their limited (instantaneous) coolin
readout ellectronics (dissiipation and harrness conductioon). Compresssor and Stirlingg cooler acousttic noise and itss proper
suppressioon has been thooroughly investtigated at ISAS
S.
6
SPICA Focal Plane Instruments
Quite a number of instrument options have been studied. We just summarize their main
features.
MIRACLE (Mid-InfRAred Camera without Lens): A mid-IR imaging camera
including a low-resolution spectroscopic capability using Silicon BIB detector arrays (Si:As
2Kx2K, Si:Sb1Kx1K, Si:X 128x128) with a field of view of 5´x5´ in imaging mode and a 5´
long slit for spectroscopy. The resolving power in spectroscopy mode is ~200. The
instrument provides continuous spectral coverage from 5µm to 38μm by 2 channels
(MIRACLE-S: 5-26μm, MIRACLE-L: 20-38μm). FoVs of MIRACLE-S and -L are separate,
but next to each other in the focal plane. The angular resolution is diffraction limited
(0.35”@5µm).
MIRMES (Mid-IR Medium-resolution Echelle Spectrograph): An integral-field
spectrometer with two independent channels covering the wavelength ranges 10µm to 20µm
and 19.5µm to 36.1µm with FoVs of 12´´x 6´´ and 12´´x 12.5´´, respectively. The spectral
resolving power is ~1000, and pixel scales are 0.4´´ and 0.5´´, respectively.
MIRHES (Mid-IR High-resolution Echelle Spectrograph): A compact highdispersion spectrograph with immersion gratings for two wavelength bands, 4-8µm and 1218µm, with slit lengths of 3.5´´and 6´´ and pixel sizes of 0.3´´and 0.5´´, respectively. The
resolving power in both bands is ~30,000.
SCI (SPICA Coronagraph Instrument): A high dynamic range coronagraph in the
mid‐IR, optimized for exo-planet observations. It works in two wavelength bands, 1-5µm
(InSb detector) and 5-27µm (Si:As detector), for non-coronagraphic imaging and
spectroscopy, and in coronagraphic mode at wavelengths >5µm, also for imaging and
spectroscopy, where the resolving power is up to 200. As a coronagraph, it realizes a contrast
of 106. Its FoV covers 1´x 1´.
FPC (Focal Plane Camera): Actually consists of two cameras, one in the visible with a
limiting magnitude of 21.5 (AB), which is part of the guiding system, and a NIR (0.8-5µm)
camera and spectrometer with a slow readout and a limiting magnitude of 26.3 (AB), also
serving as a back-up for the guider camera.
7
Hersch
hel
vv
MIR
RHES
10000
(30 km s-1)
Scie
ence
Obje
ective
SPICA
A
MIR
RACLE
MIRMES
SAFARI
(spec
ctroscopy)
(>
>20m)
MIRACL
LE
MIRMES
2 m
SAFARI
λ
MIRACLE
20 m
F
FPC-S
U.S.
Instrument
(Option)
×
(Recipe
e for Planet
Formattion)
BLISS
FPC-S
SCI
A
MIRMES
SC
CI
MIRHES
(spectrosco
opy)
(<20m
m)
R
Requirement
JWST
1000
(300 km s -1)
100
(3000 km s-11)
MIRACLE
(imaging)
B
(Planettary System
& Galaxies)
C
×
(Drama
a of Galaxy
Formattion)
avelength
200 m Wa
Essential Function
Uses part of functionality
Uses full functionality
× not applicable
Optional Functionality
Figure 3: Planned (required / optional)) focal plane in
nstruments on SPICA.
S
For eleectrical power, mass, and therrmal
budget reaasons, only a su
ubset of the opttional instrumeents can be acccommodated. The
T JAXA revieew (in progress)
s) has led
to a recom
mmendation to drop
d
any US in
nstrument at this point. The (m
mandatory) com
mbination of MIRACLE
M
and MIRMES
M
is also refe
ferred to as MC
CS.
Figure 4: Left panel: Photometric perfo
formance expeccted for SPICA SAFARI (blacck) and MCS (ggreen), comparred to
Herschel, ALMA and JW
WST (red), for a point source (μJy, 5σ, 1 hou
ur) using the gooal sensitivity detectors
d
on SP
PICA (NEP
= 2 × 10−119 W Hz−1/2 ).. Note the 2 ordders of magnitu
ude increase in
n photometric seensitivity comp
pared to Hersch
hel- PACS.
The SED oof the galaxy M82
M as redshiftted to z=1, 2, 3, 5 and 10 is shoown. Right pan
nel: Spectroscop
opic performancce
expected ffor SPICA (black and green) compared
c
to otther facilities (rred) for unresoolved line and point
p
source (W
W m−2, 5σ, 1
N that SPIC
CA becomes moore sensitive tha
an JWST beyon
nd 20μm.
hour). Forr ALMA 100km
m s−1 resolutioon is assumed. Note
Figure 5: Left panel: Maain contributorrs to the inciden
nt background flux
f
density. With
W the nomin
nal telescope tem
mperature
and approp
opriate cold baff
ffle design, phooton backgroun
nd will be predoominantly from
m celestial sourcces. Right panel:
Maintainiing a temperatu
ure of the innerr baffle of <10K
K is essential, but
b a serious deesign driver.
8
2.2 SAFARI
2.2.1 The Instrument
SAFARI stands for S(PIC)A FAR-infrared Instrument. After conception and early gestation
under UK PI leadership, SAFARI is at present under leadership of SRON (Netherlands) as the
PI-Institute.
SAFARI is an imaging spectrometer with both spectrometric and photometric capabilities
covering the ~34-210 um waveband. The baseline optical configuration was selected to be a
Mach-Zehnder imaging Fourier Transform Spectrometer. This fundamental choice was driven
by high spectrometric mapping speed, ability to incorporate a photometric imaging mode in a
natural way, operational flexibility to tailor the spectral resolution to the science programme,
and photon noise match with the detector system. The detector has been selected to be of TES
(Transition Edge Sensor) type, to be further developed in close collaboration between the
Netherlands (SRON) and the UK (University of Cardiff Astronomical Instrumentation Group
and University of Cambridge Detector Physics group). These detectors require a multiplexing
SQUID readout system with demanding specifications on input noise density and line drive
capability; presently, PTB (Berlin) is the only group to provide such devices.
SAFARI
• Instantaneous wavelength coverage from 35 to 210 micron
• Camera mode with R~3 to 5
• Multiple spectroscopy mode R = 2000 @ 100 micron
• Spatial resolution 3.6~11.5 arcsec
• Field of view 2x2 arcmin2
• Line sensitivity of 2x10-19 W m-2 (5-σ 1 hour)
• Continuum sensitivity of <50 µJy
gFigure 6: The SAFARI instrument (left), studied by a European consortium under SRON (NL) leadership, is an imaging
Fourier transform spectrometer, which feeds three TES bolometer arrays in the wavelength bands 34-60 micron, 60-110
micron, and 110-210 micron, realised with dichroic beam splitters, and provides ~Nyquist beam sampling at each band
centre. “Parked” at the white-light position, the FTS can be use as a three-band photometric camera. Main technological
developments are the FTS scanner (centre) and the detector arrays with their multiplexed SQUID readout system (right).
9
8 arrays based
8x9
d on 250 nm SiN
40 pixels:
1 mm x 2  m x 250 nm
32 pixels:
1.5 mm x 2
m x 250 nm
- W/√ Hz
T
Tc=103
mK,1.5 mm
m legs TES: NEP measured 5x10-19
Figure 7: Left: Achievedd unresolved lin
ne sensitivity on
n SPICA as a function
f
of deteector dark NEP
P for a broad baand (R~3)
Fourier T
Transform Specctrometer operaating with threee wavelength lim
mited detector bands under th
he assumption of
o a
photon baackground compprised of the Zodiacal
Z
light an
nd the Cosmic IR backgroundd. The bands ussed were centreed on 48,
85 and 160 μm and we assume
a
instantaaneous Nyquistt sampling of th
he point spreadd function – i.e.. 0.5 f/# λ pixells.
Demonstraated NEP to da
ate (thick green
n line) is 4x10-119 W/Hz1/2. Rigght: First largerr array of long--leg/low-G TES
S
bolometerrs developed at SRON, with NEP
NE close to besst single detectoor. The diagona
ally-strung legss allow a length
h greater
than the pixel
p
pitch, whicch is necessaryy for SiN with itts relatively higgh thermal con
nductivity. Ligh
ht cone arrays similar
s
in
design to tthe ones for thee PACS photocconductor arrayys are used to achieve
a
“filled”” arrays.
AFARI Connsortium Orrganisation
2.2.2 SA
The SA
AFARI Conssortium, connsisting of ~28
~ instituttes, is – to first
f
order approximati
a
ion – the
combinaation of moost institutees responsibble for the three Hersschel focal plane instrruments.
Most m
major work packages
p
haave been addopted by, already, buut some are still floatinng, while
others m
may not hav
ve found thee most com
mpetent team
ms to tackle them. Thee funding siituation /
level off commitmeent by national space agencies
a
is ssomewhat diverse,
d
but the overall level of
fundingg seems to be
b roughly adequate.
a
Since D
DLR/MPE recently
r
onlly were ablee to keep thhe SQUID developmen
d
nt at PTB alive
a
and
were noot ready to make any commitmen
c
nt, the Germ
man contribuution is maarginal in thhis chart,
but therre is a strongg wish from
m both, the SAFARI
S
PI institute an
nd the Japannese side forr a much
strongerr MPE invoolvement, ass discussed below.
b
The shaaring of thee Guaranteed Time of the SAFA
ARI consorrtium will follow the “SPIRE
scheme””, rather thaan the “PACS scheme”, i.e., theree will be working
w
grouups on a nuumber of
science themes, in which the CoIs
C
(or theeir represenntatives) cann contribute to the definnition of
10
programmes. However, there is an explicit intention by the PI institute to establish some form
of reciprocity, where CoI institutes are supposed to be “paid back” in the science programmes
in proportion to their “hard” contributions – i.e., hardware, facilities, tests, ICC work.
2.3 Science Management / ObservingTimeAllocation
The SPICA observing time will be distributed following the principle of “guaranteed” and
“open” time. Guaranteed time will be allocated to the scientific institutes directly involved in
the building of the focal plane instruments. The instrument consortia will decide internally the
distribution of their guaranteed time, under the final responsibility of the instrument PI. Open
time will be allocated to proposals submitted by general astronomers, through a competitive
process in which the TAC will provide the final recommendations. A single international
scientific Observing Time Allocation Committee will be established by JAXA, ESA and other
potential mission partners sufficiently early before launch. The composition of the TAC will
be arranged such that conflicts of interests with proposers will be avoided. It will be based on
scientific excellence.
In the following, the percentages of SPICA time for each category are specified (with respect
to total satellite time in the Nominal Observation phase):

Engineering/Calibration Time: 10%

Director’s time, including ToO observations: 5%

Guaranteed time for SPICA team: 25%. It will be shared taking into account the
relative contribution of each team to the project, and includes the guaranteed time for
instrument teams, science team members, and science operations centres.

Open Time: 60%, which will be further subdivided as:
– For astronomers from countries directly involved in the SPICA project: 40%
– For the general community, without restrictions of nationality: 20%
The time allocation to European astronomers will be proportional to the European economic
contribution to SPICA, which we assume will amount to one third of the total. Consequently,
the fraction of European open plus guaranteed time should also be one third of the “allocated”
open and guaranteed time. Within this scenario, time reserved to astronomers of the
[contributing] ESA member states is distributed in the following way:

European guaranteed Time: 8.3% of total satellite time, of which 95% is reserved for
the SAFARI consortium, 3.5% for the ESA SPICA Science Centre, and 1.5% for the
European mission scientists.

European open time: 13% of the total satellite time (or 22% of the total open time).
11
Assuming 33.000 hours are available in total (for a goal lifetime of 5 years, therefore a
mission operational phase of 4.5 years, and an efficiency of 20hrs per day) this translates into
0.083*0.95*33.000 hrs =
2.600 hrs for SAFARI
0.13*33.000 hrs
4.300 hrs for European open time
=
The return for a 10% contribution to SAFARI would therefore amount to 260hrs guaranteed
time. Assuming a total cost of SAFARI of 140Mio € this corresponds to a contribution of 14
Mio €.
One might argue, and experience has shown in some cases, that one does not necessarily have
to be a major contributor in terms of money and hardware to be a (co-)leader of one of the
major science programs if one has a strong science team that knows how to design an
observing program, brings in lots of up-to-date knowledge, complementary data and modeling
expertise. In that case it is perhaps more important to have a 'foot' in the door of the GT
program. The alternative route is to assume that the institute is scientifically strong enough to
get a large program approved in the open time. We all have our experience with TACs:
sometimes this strategy works, sometimes not. For a 5 yr mission, one would assume it is
possible to get a good chunk of time through the open route, although one may then not be the
first to do the new science.
12
3. Science Potentials
3.1 Science Cases
The ESA Cosmic Vision (ESA BR-247 2005) defines four grand themes in space science that
shall bring us closer to understanding how the Universe has come to look as it does and the
place of our Earth within the Cosmos. Based on mid-IR and far-IR observations, SPICA’s
main science objectives correspond to three of these four themes:
 Formation and evolution of planetary systems: Gas and dust in proto-planetary discs,
including water, and their link to planetary formation; mineralogy of debris discs; gas
exo-planets atmospheres; composition of Kuiper Belt objects.
 Life cycle of dust: Physics and chemistry of gas and dust in the Milky Way and in
nearby galaxies; dust mineralogy; dust processing in supernova remnants and the
origin of interstellar dust in the early Universe.
 Formation and evolution of galaxies: AGN/starburst connection over cosmic time and
as a function of the environment; co-evolution of star formation and super-massive
black holes; star-formation and mass assembly history of galaxies
A detailed description of these science cases can be found in the Yellow Book (see [RD1]).
Here we are going to concentrate mainly on those science cases which are of direct interest to
MPE/IR-Group.
3.1.1
Star and planet formation and evolution
A) The Case:
Star formation:
In the IR group Ewine van Dishoeck’s group is working directly in this area, however it does
cover several key questions that are of relevance also for galaxy evolution as a whole. For
instance in the area of different star formation efficiencies and depletion time scales:
What fraction of typical giant molecular clouds is converted into stars during their lifetime
and how does this depend on local conditions?
Or in the feedback context:
What internal sources of energy (and cooling) drive the dynamics of molecular clouds after
their formation?
There is, for instance, considerable debate about why gas does not cool and form stars
efficiently in low mass galaxies. Two main physical processes are likely at play. One is that
13
supernoovae explossions createe localized bubbles off hot gas inn the ISM,, and this ggas then
escapes from such
h galaxies very
v
easily because thheir potentiaal well dep
pths are sm
mall. The
c
phase of
o the ISM has
h low meetallicity and
d dust conteent. As a result, this
second is that the cold
m the ambieent UV raddiation field
d and may not
n be able to form
gas mayy not be shhielded from
molecullar clouds and
a hence sttars very effficiently.
Mappinng GMCs accross the brroad instantaneous wavvelength rannge of SAF
FARI at sensitivities
more thhan an orderr of magnituude beyondd the capabillities of the Herschel/P
PACS specttrometer,
would allow
a
to com
mpletely sam
mple approppriate moleccular cloud regions.
b Herschel photometry. An
n
Figure 9:: (a) Cold dusst in a dark clloud near the Southern Crooss revealed by
interconn
nected maze of
o filaments off different sizzes and amoun
nts of dust, wiith strings of newly formin
ng stellar
embryos in all phases of developmeent are revealeed in the FIR
R. SPICA specctrometers willl observe similar cold
n the Milky Way
W and also in
i the closest galaxies (e.g.., the Local Group),
G
allowiing us to inferr their
regions in
physical conditions ass well as their gas, ice and mineral
m
compposition. (b) FIR
F spectrum of circumstelllar
C
an interm
mediate-mass star in transiition from an embedded configuration too a star
material around DK Cha,
ha was observved during ≃4 hr with Hersschel/PACS spectrometers
sp
(van Kempen
n et al.
plus disc stage. DK Ch
2010). SP
PICA/SAFAR
RI will obtain simultaneouss spectra for multiple
m
objeccts, in a much
h larger FoV of
o ∼2′×2′,
with simiilar spectral resolution
r
butt ∼10 times more sensitivityy in only ∼4m
min.
For insttance, SAFA
ARI can tarrget dark clouds withoout clear siggns of star formation (like the
Coalsacck) and porttions of trigggered SFRss in the Milkky Way andd in nearby galaxies
g
succh as the
LMC (ffor which spectral
s
mappping with Herschel require unreealistic amo
ounts of tim
me). This
will alloow a study an
a importannt mode of SF
S in interacting galaxiies and the early Univeerse (e.g.
low meetallicity reegions). It will also provide a range off diversity in “star forming
environment”. Den
nse filamennts and corres in SFR
Rs are embeedded in a more difffuse and
turbulennt medium that seems to be driveen on largerr scales. Thhese more quiescent,
q
e
extended
regions constitute the
t bulk of the mass off GMCs and play a criitical role inn their evoluution. In
spite off their relevaance, the intterfaces bettween the sttar forming cores and the
t environm
ment are
due to their much loweer surface brightness)
b
a thus
and
poorly ccharacterizeed spectrosccopically (d
remain poorly undeerstood. Whhile Herschhel spectral surveys tow
wards brightt star forminng cores
(Orion, W49, W3, Taurus, Serpens...) proovide the most
m compleete informattion on the physical
o star form
mation (hot cores, protoostars or
conditioons and cheemical conteent of particcular sites of
HII regiions), they do not placce the obserrvations in tthe context of the largee scale gas and dust
emission of the clo
oud, i.e., their environm
ment.
14
Protoplanetary and debris disks
Planets form in disks around young stars during the collapse of the parent molecular cloud
cores. Our understanding of the physical and chemical conditions in such disks is still very
incomplete, in particular how they evolve from the gas-rich protoplanetary phase to the gaspoor debris disk phase and how planets as diverse as the hot Jupiters and (super-)Earth-like
planets form as function of stellar type and location in the galaxy. ISO and Herschel-PACS
have shown that far-infrared spectroscopy is a powerful and unique tool to determine the
physical structure of the gas, the major carbon- and oxygen chemical species (CO, C+, H2O,
OH, O) and the mineralogy of the dust grains in the planet-forming zones of disks. However,
ISO and PACS have been able to survey only about 20 of the brightest disks around
intermediate mass Herbig Ae/Be stars. The majority of the Sun-like T Tauri stars were too
faint even for Herschel.
B) Assessment and Feasibility:
ALMA observations of YSOs will soon help us to resolve their inner structure individually
(below scales of a few tens of AU), however ALMA is not designed to map the large scale
distribution of gas and dust in GMCs (with spatial scales of several parsec). A full picture of
their physical conditions (energy budget, neutral/ionized gas filling factors, density and
temperature gradients) has great relevance for Astronomy since it is the widespread gas and
dust (the environment) that sets the initial conditions for star formation in diverse regions.
SAFARI will map these faint extended regions both in the dust continuum and gas lines
simultaneously. Ground-based single-dish sub-mm telescopes (IRAM, JCMT or CCAT in the
future) are able to map the low energy transitions of molecules like CO, CN, C2H, ... and the
sub-mm dust continuum emission over large spatial scales. However, they cannot access the
brightest gas cooling lines ([Si II]34, [OI]63, [C II]158, ...) and they cannot observe the dust
SED peak (essential to determine the dust temperature). SAFARI’s large field of view will
also help us to trace the action of parsec-scale molecular outflows as they impact the ambient
inter-clump medium and the role of UV radiation at large scales. In order to answer the
questions posed above, a coordinated spectral survey with SAFARI of several clouds that
cannot be accessed spectroscopically with Herschel, both locally and in nearby galaxies is
vital.
The Herschel HiGAL key program will survey the entire galactic plane from 60 to 600 micron
and, combined with Spitzer-GLIMPSE data, should be able to find all young stellar objects
down to the low-mass regime and thus determine star formation efficiencies as functions of
environment and galactocentric radius. The HERITAGE - SAGE key programs can do the
same for the LMC and SMC, down to a higher-mass limit, and allow studies as function of
metallicity. Therefore, there currently does not appear a strong science case to re-do the
Galactic plane photometry mapping with SPICA (except perhaps the 45 micron channel).
15
On the other hand, Herschel is performing only very limited spectral mapping of galactic
clouds. Although more than 100 (low and high-mass) YSOs are targeted by PACS/SPIRE
spectroscopy, most of them are at a single staring position covering just the instrument
footprints around the source. Only a handful of PACS maps of ~5-10' in size have been made
and then usually just in a single line (see the L1157 H2O map example). Thus, there is a great
opportunity for SAFARI to map large areas on scales of tens of pc in all the major gas cooling
FIR lines (CO, H2O, OH, [O I], [C II]), investigate how their (relative) contributions change
with position from the exciting source, and quantify the feedback effects of UV photons vs Xrays vs outflows and shocks. This should result in a better understanding of the feedback
mechanisms and allow a much closer connection to be made with the extragalactic star
formation science.
With its increased sensitivity by a factor of 10 and more, SAFARI can survey hundreds of T
Tauri disks and study their structure as function of spectral type, age, accretion rate, etc. This
is particularly exciting because Spitzer spectroscopy has shown that the T Tauri disks are
much more line-rich than the Herbig disks, so that many surprises are likely. Also, the T Tauri
disk composition allows a much more direct link to be made with solar system and exoplanetary atmosphere studies. The SAFARI data would be complementary to ALMA
observations, which probes the cooler gas and dust deeper in the disk.
16
3.1.2
Exoplanets
We list this topic here in case there is interest in the institute to get more involved in this
science area in the future, be it, e.g., in the context of the new/planned Harvard – MPG Center
for Interdisciplinary Astrophysics Frontiers (CIAF), or perhaps in the context of the Morfill
succession.
C) The Case:
The observation of exoplanets (EPs) at IR wavelengths offers several advantages compared to
traditional studies in the visible domain. First, the star-to-planet flux contrast is much lower
than in the visible and second, transiting planets around stars much cooler than the Sun have
to be observed in the IR where their emission peaks. The mid infrared region is particularly
rich in molecular features that can identify the composition of planetary atmospheres and
potentially trace the fingerprints of primitive biological activity.
Two different observational approaches can be used to characterize both outer and inner EPs:
direct detection and transit techniques. Direct detection refers to observations where the
star and the planet can be spatially separated on the sky with coronagraphs. Due to the limited
size of current telescopes, this technique is only able to image EPs at large orbital distances.
EPs orbiting very close to the host star (< 0.05 AU) and with a favorable inclination (almost
edge-on systems) can be indirectly studied via the transit technique, i.e. by observations when
the EP passes in front or behind the star. Although not specifically designed for EP research,
transit observations with Hubble and Spitzer have been successfully performed over the past 5
years. Spitzer, e.g., has measured EP photometric transits out to 24 μm demonstrating that the
light-curve is simpler (“box-like”) than in the visible domain due to the negligible role of
stellar limb-darkening effects. This allows a better determination of the EP radius as a
function of wavelength and provides further strong constraints on the atmospheric properties.
Transit observations with the Spitzer-IRS MIR spectrometer have been used to extract the
absolute intrinsic spectrum of HD209458b hot Jupiter around a Sun-like star.
Chromatic Differential Astrometry (CDA) is a concept to determine the orbital parameters
and the spectra of EPs via measurement of the displacement of the photo-centre of a source as
a function of its wavelength. It can be applied to inner (0.05 < a < 2 AU from their parent),
Jupiter mass exo-planets that cannot be spatially resolved from their parent stars. CDA does
not require the planetary orbit to produce eclipses. Therefore this method is complementary to
both coronagraphic direct observation and planetary transit monitoring techniques.
While transit spectroscopy with SPICA is currently being discussed for the mid- and far-IR
spectrometers MCS and SAFARI, a dedicated FPI for coronographic imaging and
spectroscopy (SCI) is under review, too (see chapter 2.1).
D) Assumptions and Feasibility:
In the coming decades many space and ground based facilities are planned that are designed
to search for EPs on all scales from massive, young “hot Jupiters”, through large rocky
17
“super-Earths”, for inner planets as well as for outer planets. For instance, EPs are part of the
GRAVITY science case (employing astrometric and micro-arcsecond imaging and the CDA
technique). SPICA’s capabilities towards exo-planet science has to be judged in this
environment of competing projects. Few of the planned facilities, however, will have the
ability to characterize the atmospheres which they discover through the application of infrared
spectroscopy. For instance, JWST will have photometric coronagraphs in the MIR but without
spectroscopy. Other direct imagers/coronographs are available with NACO (e.g. beta Pic was
observed with this), GPI (Gemini Planet Imager), HiCIAO at SUBARU, or Nulling
Interferometry (e.g. at Keck). Ground based transit surveys are performed, e.g, in the projects
HAT (CfA), WASP (UK), XO (STScI), while space-based transit surveys are done with, e.g.,
COROT (a CNES/ESA mission). Other space-based EP missions, which are planned or on
hold are, TPF (NASA), Darwin (ESA), SIM (NASA), or TESS (NASA SMEX).
The M3 ESA mission EChO (Exoplanet Characterisation Observatory) is currently under
assessment. If selected, it will provide high resolution, multi-wavelength spectroscopic
observations, covering continuously the 0.4-16 µm spectral range. It will be placed in a grand
halo orbit around L2. Echo was designed and optimized to look at transiting planets.
Other spectroscopic projects are designed for the search for earth-like planets (like the
CARMENES project at Calar Alto, a radial-velocity survey of exo-planets around M dwarfs
with optical to NIR spectroscopy, or ESPRESSO at the VLT).
A comprehensive comparison and assessment of SPICA’s abilities and complementarities
with respect to all these existing or planned missions is out of the scope of this white paper.
The capability for mid-IR spectroscopy combined with a coronagraph is certainly the most
important point to be mentioned as a SPICA advantage. Constraining the temperature and
atmospheric composition will greatly help in the analysis of all the near-IR/ground-based
planet finders (like GPI, or SHERE at the VLT). In addition to the clear advantage of doing
mid-IR spectroscopy further complementarity will come from the various kinds of EPs that
the different missions will measure with different techniques (e.g. outer vs. inner, giant gas vs.
earth-like rocky etc). In this context SPICA (/CSI) will be able to study outer, giant, gas like
planets.
A critical number for the assessment of the potential exo-planet science with SPICA is the
contrast that can be reached. The baseline design for the SCI supposes the contrast at PSF to
be 10-4, which is only marginal for the detection of a significant number of exo-planets. An
advanced design supposes the contrast at PSF to be 10-6 with wave front control by a
deformable mirror. This design is, however, considered to be not mature enough in the
currently ongoing assessment study. The SCI team has therefore performed simulations of
methods to enhance the contrast by the subtraction of the PSF (observed with reference stars).
Taking into account pointing instabilities and wavefront errors they could show that the
contrast can be enhanced to 10-5 - 10-6 even without a deformable mirror by such subtraction
techniques. The expected number of detectable planets with SCI is then, depending on
wavelength, several tens to more than hundred. This depends also on the age of the system
and the distance of the planet form the parent star.
18
3.1.3
Galaxy evolution
A) The Case:
Galaxy evolution is one of the central themes of the IR-group and of the MPE as a whole.
With ISO, Spitzer and Herschel (for instance) we have pioneered many different methods of
mid- and far-IR diagnostics to characterize and quantify the nature of galaxies and the
respective roles of star formation and AGN activity therein. We have spent large efforts with
the goal to understand and unravel all kinds of relationships, e.g. between the black hole
growth and bulge formation, between SFR and stellar mass, star formation efficiencies and
modes of star formation, etc.
The big next step forward that SPICA (in particular SAFARI and the medium resolution
branch of the mid-IR spectrometer) promises is the ability to apply, more or less for the first
time and to a large extent, the aforementioned diagnostics based on mid-to-far IR line
spectroscopy to galaxies at medium and high redshifts. These will provide measured (rather
than estimated) redshifts and also unambiguously characterise the detected sources, by
measuring the AGN and starburst contributions to their bolometric luminosities over a wide
range of cosmological epochs.
The wide SAFARI FOV of 2′ × 2′ will make it possible for the first time to collect blind
spectroscopic surveys, wide and deep enough to measure the underlying physical processes
driving galaxy evolution out to z ∼ 4 and, in the most luminous/lensed objects, to even higher
redshift. By comparing blind surveys with those targeted around known, high-z objects, it will
also be possible to determine the role of environment on galaxy evolution.
Below we mention just very briefly some of the potentially interesting science cases:
-
AGN feedback: outflows of molecular gas in warm and cold phases
Mass outflows driven by stars and active galactic nuclei are a key element in many
current models of galaxy evolution. The successful Herschel-PACS measurements of
molecular outflows in the local Universe can be extended by SAFARI to higher
redshifts
-
Querying for the obscured AGN missing from the X-ray background
and
Accretion history of the Universe and black hole masses in obscured
environments
The construction of luminosity functions from high ionization lines (like [OIV]) can
be used as a means of studying the accretion rate history of the Universe that is an
alternative to X-rays, in particular for Compton thick sources. The widths of the same
lines depend on the kinematics of the clouds that they probe, determined by either the
gravitational potential out to a radius that the AGN luminosity dictates, or by AGN
feedback effects. They can be used to weigh the masses of black holes, permitting the
19
ccreation of black
b
hole mass
m functions that incclude obscurred AGN with
w SAFAR
RI out to
rredshift of 4 using the [OIV] line.
-
M
Molecular
content evolution of the
t Universse
D
Detection of
o the pure rotational linnes of H2 (S
S(0) and S(11)) will be feasible
f
for various
v
z ranges (ouut to z~2) inn deep SAFA
ARI surveyys. To date, beyond the local Univeerse H2
hhas only been detectedd in stacked spectra of z ∼ 1 galaxiies.
-
S
Spectrosco
opy of faint galaxy pop
pulations th
hrough graavitational lensing
W
Wide-field surveys likee Herschel-ATLAS aree finding maany lensed systems
s
at high
h
rredshifts. With
W SAFAR
RI, it will beecome possible to studyy these lenssed galaxiess with
((rest-wave) mid-IR speectroscopy.
-
B
Beating
spaatial confusion
T
The third, sppectral dim
mension offeered by specctroscopic suurveys prov
vides us with a way
tto overcomee confusionn even in thee deepest exxplored field
ds. Narrow--band line emission
e
ffrom a sourrce at a giveen redshift appears
a
onlyy at very speecific and discrete
d
w
wavelengthhs, and so thhe high denssity of sourcces in an ind
dividual beaam that causses
cconfusion iss drasticallyy reduced reelative to alll sources em
mitting in th
he continuum
m. This
aallows to deetect and stuudy individuual objects, whose conntinuum mayy be substanntially
bbelow the continuum cconfusion lim
mit.
Figure 10: A 5′ × 5′ reg
gion taken frrom an off-so
ource part of a 250 μm ES
SA SPIRE pu
ublicity
h the 2′×2′ FO
OV of SAFAR
RI outlined (ccredit: ESA an
nd the SPIRE
E consortium)). With
image, with
its spectral imaging capa
ability, SAFA
ARI will be ab
ble to obtain spectral
sp
inform
mation coveriing the
full 34 − 2110 μm range, in multiple so
ources, simulttaneously – in
n a single poin
nting
20
B) Assessmen
A
t and Feasiibility:
As brieffly summariized above deep integrral field specctroscopic surveys
s
usinng a fully crryogenic
far-infraared space telescope
t
haave large pootential. At sufficient seensitivity thhey can
• Detectt large numbbers of highh-redshift gaalaxies and determine their
t
luminoosities/SFRs.
• Directtly measure their redshiifts withoutt need for iddentificationn at other wavelengths.
• Partly break the confusion
c
lim
mit which is affecting bbroadband far-infrared
f
d measuremeents.
• Study the energy sources andd ISM condditions, via a variety of mid- and faar-infrared lines.
l
• Study their host dynamics
d
viia integratedd line profiles or line widths.
w
Spinogllio et al. (seee [RD2]) have
h
presen
nted predictions for su
uch surveyss. They adoopt three
differennt simple ‘bbackward evvolution mo
odels’ (Grupppioni et all., Francesch
hini et al., Valiante
et al.) w
which are calibrated
c
m
mostly
on pre-Hersche
p
el (and parttly early Herschel)
H
brroadband
infraredd/submm daata. They thhen use relattions of linee flux to LIIR, based on
n a small saample of
local AG
GN hosts and
a a yet sm
maller sampple of star forming
fo
galaaxies, to deerive predicttions for
high z sspectroscopiic surveys. T
This is a strraightforwarrd approachh. A numberr of questions about
the detaailed appro
oach of Spiinoglio et al.,
a plus a desire to be
b able to ‘play’
‘
withh models
motivatted some quuick own exxperiments which are described in the note by
b DL and JG (see
[RD3]).. The Spinoglio results broadly agrree with ourr own resultts.
We adoopt the depthhs for a 1hrr per field survey
s
of 0..5 sq.deg. (4
450hr total,, from 450 fields of
2x2arcm
min) as Sppinoglio et al.: 4.16, 2.58, 2.488×10−19Wm
m−2 for 34––60, 60–110, 110–
210μm.The following table giives the stattistics of hoow many soources are detected
d
aboove 3 (5)
sigma inn 1, 2, etc. lines,
l
over the
t entire reedshifts rangge, and for a restricted redshift rannge z≥1:
In 450 iindependennt pointingss there are > 5σ detectiions in at leeast one linne of ∼50000 distinct
sources. A sensitivity optimizeed single ap
perture specctrograph would need to
o be ∼3 tim
mes more
ming for a characterisaation of a specific
sensitive. The traddeoff may differ wheen e.g. aim
populatiion (here thhe multiplexxing advantaage will be reduced).
r
Berta ett al. 2010, 2011
2
derive counts and
d Herschel confusion
c
lim
mits at 100 and 160μm
m. To the
16.7 beaams/source confusion limit there are about 12000 and 6000
6
sourcees per square degree
respectiively, half of
o that (60000 and 30000) in our fiiducial survvey. While this means that the
21
fiducial Safari survvey is not yet workinng massivelly into breaaking the broadband
b
H
Herschel
confusioon, it will reeach it and already
a
help
p breaking the
t inevitab
ble blends.
More thhan half of the
t sources (∼2500) haave > 5σ detections in at
a least twoo lines whichh should
provide robust reddshifts. [OI] and [SiII] may be veery relevantt here. Thiss number shhould be
possiblee to increasse, by combbining robu
ust single lines with phhot-z, or byy considerinng more
all redshiftts based on emission liines will bee at z<3,
modest SNR line detections.
d
E
Essentially
R galaxies. We did NO
OT check foor use of
i.e not ffix the redshhifts of the high redshift tail of IR
the PAH
Hs here.
Makingg the simpliffied assumpption that linne widths sttart to be usseful at SNR
R>10, we fiind 1721
sources with at leasst one such line, of whiich 845 are at z≥1.
Below w
we summarrize the resuults of [RD33] for one of
o the modells. For each
h line the nuumber of
detectioons for variious redshifft bins and for 3 and 5 sigma is given. Forr further deetails see
[RD3].
CII 158:
OI 145::
OIII 88:
OI 63:
NIII 57:
OII 52:
3
NeIII 36:
SiII 35:
SIII 33:
H2 S(00) 28
FeII 26:
NII 122:
22
OIV 26:
NeV 24
4:
SIII 18:
H2 S(1)) 17:
NeIII 15:
1
NeV 14:
NeII 12:
For reassons given in [RD3] thhe OIV linee predictionns are probably a bit underestima
u
ated. We
also notte that this overview does
d
not coover the miid-IR spectrrometer, wh
hich will fiill in the
mid-IR line detecttions at low
wer z. These numbers should be compared to Herschel-PACS,
which ccan only detect
d
the very
v
brighttest mid-IR
R (and far-IIR) lines inn several hours
h
of
integrattion per linee on the mosst luminouss objects at tthese redshiifts.
The largge number of multi-linne detectionns at decennt S/N will imply interesting diaggnostics.
Most off that will be
b in OI, OIII,
O
SiII at z∼1. The classical
c
SW
WS/IRS restt mid-IR diiagnostic
(here foor z∼2) is more limitted in num
mber (still few
f
hundreed) and empphasizes SM
MG-like
objects.
23
4. Potential MPE Contributions
A contribution to the SAFARI project could have several advantages:
- access to guaranteed time (with first choice of targets and science topics)
- access to privileged open time (or privileged access to open time)
- in-depth instrument and software knowledge right from the beginning of the observations
- preservation of know-how in the group for space-based operations
- maintain and extend a world class expertise in far-IR detector technology
However, in order to benefit from this on a significant level, the contribution has to reach a
“critical mass” below which the gain in knowledge is insignificant and a participation in the
regular open time competition could be more efficient. As described in section 2.3 260 hours
of guaranteed observing time would be equivalent to ~14 Mio € (pending the exact modalities
of GT collaborations). We describe here a potential scenario (with several options) for MPE’s
contribution that would reach this “critical mass” in our opinion.
4.1 Involvement up to now
Members of the MPE have been involved in the SAFARI development work since 2004 and
have played a central role in all phases of the instrument definition and development. Prior to
the move of PI-ship to SRON, a member of the MPE (WR) has been the instrument scientist
for SAFARI. Besides our general participation in the instrument development, our main
points of involvement so far include the investigation of an alternative (grating) spectrometer
design, an upgrade of the “GIRL mechanism” to be used for the FTS scanner stage and the
development of large scale photoconductor arrays suitable as baseline “state of the art”
detector arrays for SAFARI. AlPog, DL and ES have been involved in the Cosmic Vision
proposal and the Yellow Book. AlPog is the leading SPICA coordinator (“Head of Nation”
board) for Germany. EvD and ES are members of the ESA SPICA science advisory team and
focal plane instrument review team.
4.2 Suggestions for future contributions
MPE and its IR-Group have gained significant expertise in almost all aspects of scientific
infrared space missions during the development of ISO-SWS and Herschel-PACS. Hence,
there is a large number of areas for the institute for getting involved in a next generation farIR satellite. During discussions within the SAFARI consortium over the last few years, the
following points for a potential MPE involvement have emerged:
24
-
Participation in the SAFARI instrument control center
-
Detector system tests
-
SQUID array and cryogenic pre-amplifier development
-
Cryo-mechanism (filter wheel) development
In the following sub-chapters we give a detailed overview over each one of these potential
points of involvement. Special emphasis has been placed on the following crucial parameters:
timeline (beginning and end of our involvement), required personnel (personnel employed at
MPE other than central services), in house resources (resources required from central
services) and required budget (total cost other than personnel). The quotes for times and
numbers arise from the knowledge we have to date and therefore represent the best estimate
we can make at this point of time.
In addition to the detailed list of required resources, we will present a summary of total costs
at the end of this chapter, including an assumption about a split between MPE and DLR. It is
important in this context that all possible contributions listed below are independent of each
other, and committing to any one point does not necessarily imply an involvement in any
other. For simplicity, we have assumed below a rate of 65.000€/year for all kinds of staff
costs. All FTEs are to be understood as FTE per year.
4.2.1
Participation in the Instrument Control Center (ICC)
Based on the extensive experience of previous missions (e.g. the PACS ICC), our institute has
gained tremendous expertise in all aspects related to the Instrument Control Center of space
missions. Participation in the ICC could therefore cover almost all segments of the SAFARI
ICC, especially: software development including data reduction tools, instrument
commanding modules, quick look and real time analysis tools as well as EGSE related
software developments, documentation (observer’s manual, calibration documents, etc...) as
well as user support during the mission life time of SPICA. In the context of a potential ICC
participation, the MPE could also provide calibration scientists, who would contribute to the
planning of calibration and observing procedures, but also take an active role in instrument
test campaigns at all phases of the instrument development. This role would be especially
valuable as it would provide insight into the details of instrument operation, which will – as
experience has shown – provide a significant advantage for both, the planning of actual
SAFARI observations, as well as the reduction of the highly complex data products of the
instrument.
Timeline:
A fully staffed ICC is required from the beginning of 2017 (SAFARI QM delivery) until mid2027 (end of SPICA mission). A ramp-up of the ICC staff will be required between 2012 and
end-2016.
25
Suggested personnel and required budget:
6 FTE for 10 years (2017 – 2027) with a ramp-up of 1 FTE/year over 5 years (starting in
2012) will be required for the envisaged contribution to the SAFARI ICC. The cost of this
involvement consists mostly of personnel cost. Additional 100 k€ will be required for
computer infrastructure and travel costs.
The total required effort for this involvement is 78 man years. The total cost for the ICC
contribution, including personnel and computers will therefore be 5.2 M€ (over 15 years,
including ramp-up phase). Assuming a split of 24 FTE (MPE) : 54 FTE (DLR) (i.e. ~1:2) this
would mean an average MPE contribution equivalent to ~1.6 FTE/year.
In-house resources (central services):
DV-group: computer system support: 0.5 FTE over 10 years (2017 - 2027)
4.2.2
Detector System Tests
MPE was approached by the SAFARI PI and the AIV manager to support the detector and
sub-K cooler qualification program. This package encompasses the development of an optical
test setup and the verification of the functionality of the fully integrated FPAs (Focal Plane
Assembly = detector arrays + read-out + thermal/EMC shield) in conjunction with the sub-K
cooler assembly. These tests will form an intermediate integration verification step between
detector array tests and the full ILT (Instrument Level Test) and will therefore include:
-
Functional verification of all deliverable FPAs with the SAFARI sub-K cooler
-
Optical tests on array level (sensitivity, spectral response, cross talk, ghosts, PSF)
-
Functional test of the FPA – DPU (data processing unit)
-
Standby operation as troubleshooting test bench during QM and FM ILTs
-
Full documentation of test setup and test results according to SAFARI qualification
procedures
The two natural phases of this contribution consist of: 1) Development and assembly of the
test system and 2) The actual test campaigns.
4.2.2.1 Development and Assembly of the Test System
This phase covers the time for design and procurement of the test system and its components,
especially: test cryostat with representative cable harness, optical components, light sources,
cryo-mechanisms (moving pin hole, spectrometer), independent sub-K cooler and auxiliary
electronics. This phase also includes time for test runs and commissioning of the test system.
26
The most demanding aspects of this development are the high requirements for light-tightness
and straylight control within the test system.
Timeline:
The test system needs to be ready end-2014 (QM FPAs are delivered). This means the
development of the test setup will need to start latest mid-2012, assuming 2½ years of
development time. A steep ramp-up of our involvement during the first half of 2012 is
therefore required.
Required personnel:
A total of 3 FTE over one year (ramp up during 2012) and 6.5 FTE over 2 years (2013 &
2014) is required to successfully complete this phase. This includes specialists (1 FTE each)
for cryo-mechanisms, optics, electronics, computer systems, a PA/QA expert and a
management/coordination position, as well as the “phasing in” of a detector specialist during
2014.
The total required effort is 16 FTE corresponding to a total cost for personnel during this
phase of 1.04 M€. Here we would consider a split of 7 (MPE) : 9 (DLR) reasonable.
In-house resources (central services):
Konstruktion: mechanical design (external): 1/2 FTE during 2012 + 1 FTE over 2 years (2013
& 2014).
Mechanical workshop: most mechanical components (besides cryostat): 2 FTE over 2 years
(2013 & 2014).
Electronics workshop: manufacture of cable harness and auxiliary electronics: 1 FTE over 2
years (2013 & 2014) + 1/2 FTE during 2015.
DV-group: computer system support: 1/2 FTE over 2 years (2013 & 2014)
Required budget:
Cryostat with optical components, cable harness and additional sub-K cooler:
750 k€
Auxiliary electronics equipment (EGSE):
70 k€
Computer system + cards:
50 k€
Mechanism control electronics:
50 k€
General lab equipment:
50 k€
Test runs/commissioning:
30 k€
==========
Total required budget for the test system preparation phase:
1 M€
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4.2.2.2 Actual Test Phase
All deliverable FPAs (SW, MW, LW on QM, FM and FS level) and sub-K coolers will need
to be tested. Test results and recommendations for operation of detectors and coolers will be
reported to the SAFRAI detector sub-system manager, AIV manager, PM and PI. The test
system needs to be kept ready as troubleshooting test bench during QM and FM ILTs.
Timeline:
Qualification tests of the QM FPAs will start beginning of 2015 (beginning of 2017 in case of
the FM FPAs). The test setup will further be needed for FS FPA tests and as troubleshooting
test bench until SAFARI FM delivery to JAXA (July 2019). The actual test phase will
accordingly begin 2015 and end mid-2019.
Required personnel:
A total of 6 FTE over 5 years is required during this phase. This includes positions for (1 FTE
each): a cryostat operator, a detector specialist (to be phased in during 2014), a software
specialist, a computer system specialist, a test supervisor/manager/coordinator, and a PA/QA
expert.
The total required effort during this phase is 30 man years (proposed split: 10 MPE, 20 DLR),
corresponding to a total cost for personnel 1.95 M€.
In-house resources (central services):
Electronics workshop: supporting test campaigns, auxiliary equipment: 0.25 FTE over 5 years
(2015 - 2019)
DV-group: computer system support: 0.5 FTE over 5 years (2015 - 2019)
Required budget:
The running costs for the test phase will mostly be due to liquid helium consumption. The
total cost for this phase is estimated to be 135k€ (over 5 years).
4.2.3
SQUID Array and Cryogenic Preamplifiers Development
Development of ultra-low noise SQUID arrays is a key element of the SAFARI detector
development program. The actual development is carried out by PTB (PhysikalischTechnische Bundesanstalt) – one of the leading institutions in metrology systems. PTB has
already started working with MPE to provide SQUID read-outs for the SAFARI detector
prototypes. The main role of MPE for this development is to provide support for PTB. MPE
will also need to find (and support) an industry partner for space qualification of the SQUID
arrays/read-out system.
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Timeline:
It is important to realize, that the SQUID array development needs to be strictly synchronized
with the overall detector development schedule. The schedule calls for delivery of following
models: EM – Spring 2013, QM – early 2015, FM – early 2017, FS – mid/end 2018. The
collaboration with PTB has already been initiated and development work has started. The
development will end with the delivery of FS detector modules in 2018.
Required personnel:
Development of SQUID arrays and cryogenic pre-amplifier will mostly be carried by PTB
and a – yet to be determined – industry partner. No hardware development or tests are planned
at the MPE. Significantly less personnel is therefore required at MPE as compared to the
already mentioned development tasks. The required personnel consists of:
1 FTE for 7 years (2012 - 2018): coordination/management, support of external partners
1 FTE for 6 years (2013 – 2018): detector specialist (partially PA/QA)
1 FTE for 7 years (2013 – 2015): electronics specialist, support of external partners (partially
PA/QA)
The total effort for this development is 20 man years (proposed split: 8 MPE, 12 DLR) with
total cost for personnel of 1.3 M€.
In-house resources (central services):
Due to the nature of this development program, no in-house resources are required.
Required budget:
The deliverables of all SAFARI detector arrays (2 EM, 3 QM, 3 FM and 3 FS) need to be
equipped with suitable SQUID read-out arrays. Assuming a unit cost of 100 k€, procurement
of these arrays will require 1.1 M€. An additional 750 k€ will be required for space
qualification of these arrays. The development of cryogenic pre-amplifiers will also require
750 k€.
The total required budget for the SQUID array/cryogenic amplifiers is 1.5 M€ (over 7 years).
4.2.4
Filter Wheel Development
The SAFARI instrument employs 2 filter wheels, one for the long wavelength band and one
which is shared by the short and mid wavelength bands. The most demanding aspect of this
development is the extremely low power dissipation dictated by the thermal budget of the
spacecraft. Filter wheel development is currently carried out by INTA in Spain, but in light of
the difficulty of the task, SRON has expressed its whish for a more significant involvement of
MPE based on the experience gained during the development of the PACS cryo-mechanisms.
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As the development of the filter wheels is mainly to be carried out by industry, this item
mostly consists of industry support, with qualification tests performed at the MPE. These tests
would require the development of a cryogenic test system including:
-
Modification/adaptation of an existing cryostat
-
Development of lab/auxiliary electronics and cable harness
-
Documentation of the test setup and test results (the actual qualification
documentation is to be prepared by industry)
It is important to note, that this test system is by far less demanding than the one required for
the detector/system tests discussed above. Because the filter wheel development is carried out
by another institute (INTA) at the moment, we list it here and in the summary table below as
“special option” only, i.e. separately from the other options.
Timeline:
According to the SAFARI schedule, the following models need to be delivered:
EM: beginning of 2014, QM: mid-2015, FM beginning 2017. The filter wheel development
would start beginning of 2012, with first qualification measurements starting mid-2013. FS
tests would continue until SAFARI FM delivery (mid-2019). Considering the tight schedule
for this development (EM delivery is required already 2 years from now!), it seems clear, that
a steep ramp-up of efforts already during 2012 will be required.
Required personnel:
Industry support will require 2 FTE over 8 years (2012 – 2019). These 2 FTE are included in
the following, more detailed list of required personnel for the entire development (including
test system development and qualification tests):
1 FTE for 8 years (2012 - 2019): Cryo-engineer, test system design, industry support
1 FTE for 8 years (2012 – 2019): coordination/management/test supervisor, industry support
1 FTE for 3 years (2013 – 2015): Electronics development
1/2 FTS for 7 years (2013 – 2019): computer system support/software specialist, data analysis
1 FTE for 6 years (2014 – 2019): PA/QA (external)
The total required effort for this development is 28.5 man years (split: 9 MPE, 19.5 DLR),
corresponding to a total cost for personnel of 1.85 M€.
In-house resources (central services):
Konstruktion: mechanical design (external): 1/2 FTE during 2012 + 1 FTE over 2 years (2013
& 2014).
Mechanical workshop: mechanical components for cryostat modifications: 1 FTE over 1 year
(2013).
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Electronics workshop: 1 FTE over 1 year (2013) + 0.25 FTE over 2 years (2014 & 2015).
DV-group: computer system support: 0.5 FTE over 7 years (2013 - 2019).
Required budget:
The development plan calls for delivery of 6 filter wheel models (1 EM, 1 QM, 2 FM and 2
FS). The total cost of all deliverables is 300 k€, assuming a unit cost of 50 k€. On top of this
figure, the additional 85 k€ arise for the development of the test system and performing the
actual tests: 30 k€ (cryostat modification), 40 k€ (driver electronic + auxiliary equipment),
15 k€ (qualification tests).
The total estimated budget for the filer wheel development is 385 k€.
4.2.5
Summary
The following table summarizes the cost (in units of M€) of each potential
participation/development item as well as the total cost of all aforementioned items. The table
is broken down in total cost for personnel and budget, and shows how we propose to share the
total cost between MPE and DLR.
Time of
involvement
Personnel cost
Required budget
Total cost
total
MPE
DLR
total
MPE
DLR
total
MPE
DLR
ICC
Participation
2012 - 2027
5.07
1.56
3.51
0.1
0
0.1
5.17
1.56
3.61
Detector System
Test
2012 - 2019
2.99
1.1
1.89
1.14
0.29
0.85
4.13
1.39
2.74
SQUID Array
Development
ongoing 2018
1.3
0.52
0.78
2.6
0
2.6
3.9
0.52
3.38
Filter Wheel
Development
2012 - 2019
1.85
0.585
1.27
0.385
0.085
0.3
2.24
0.67
1.57
Grand total, all participations/developments (M€)
15.44
4.14
11.3
Grand total, without filter wheel development
13.2
3.47
9.73
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