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December 14, 2001MISU Page 1
DARWIN
Detecting & Analysing
Remote Worlds
through
Interferometric Nullinga vessel
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Darwin - the search for biospheres
“Biosphere”
=
Planetary Atmosphere
+
Bioactivity
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Darwin - the search for biospheres
Do planets outside the solar
system exist?
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Darwin - the search for biospheresHubble Space Telescope
HH 30 protoplanetary disk
HH 30supersonic plasma-jet
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Darwin - the search for biospheres
…planetary transit observational proof!
Exoplanets do exist!HD 209458 - Hubble Space Telescope
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Darwin - the search for biospheres
Radial velocity survey:
observation of >3000 G-M starsabout 70 stars with exoplanets identifiedobservational limit: about 1 m/s
Similarities/differences wrt solar system(1) projected mass vs semimajor axis
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Darwin - the search for biospheres
Similarities/differences compared to solar system(2) eccentricities
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Darwin - the search for biospheres
Search for exosolar Earth-type planets
Radial velocities: <10 cm/s
Astrometry: <3 arcsec (10-11 rad)
Dynamic range: VIS 109
MIR 107
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Darwin - the search for biospheres
Search for exosolar Earth-type planetsRadial velocities: <10 cm/s
Astrometry: <3 arcsec (10-11 rad)
Dynamic range: VIS 109
MIR 107
log
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Darwin - the search for biospheres
Needs large telescope for resolutionand
“mask” for contrast
telescope 30 m … in space!
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Darwin - the search for biospheres
The masking device:a
Nulling Interferometerwith
rejection < 10-5
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Darwin - the search for biospheres
(2) to take IR-spectra of these x-tremely weak point sources
i.e. an instrument that is capable
(1) to image at high resolution x-tremely weak point sources
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Darwin - the search for biospheres
(1) to image at high resolution x-tremely weak point sources
DARWINSimulation of Solar System
at 10 pc distance
Date: January 1, 2001 Ecliptic inclined by 30°
nulled SunVenus Earth
Mars
Mennesson & Mariotti (1997)
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Darwin - the search for biospheres
(2) to take IR-spectra of these x-tremely weak point sources
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Darwin - the search for biospheres
5 to 20 m region contains molecular bands
…bio-markers...6 8 10 12 14 16 18
CO2
H2O
H2O
O3
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Darwin - the search for biospheres
Life on Earth as a reference:
C-based chemistry in H2O solution
….produces Oxygen
6 8 10 12 14 16 18wavelength (m)
O2
O2 + O + M O3 + M
oxygen photosynthesis
2H2O + CO2 + 8h CH2O + O2 + H2O
O3
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CO
CO2
UV
O2
O
UV
H2O
O
H
O2
OH
esca
pe
CO
CO2
UV
O2
O
abiotic=
photochemical O2
production
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Darwin - the search for biospheressame processes that produce abiotic O2
destroy O3 (radicals from H2O photolysis)or
screen the O3 signature (CO2 absorption)
Claim: photochemistry cannot reproducetriple signature of oxygen photosynthesis
O3 - CO2 - H2O
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-4
-2
0
2
4
0,5 1,5 2,5 3,51,0 2,0 3,0 AU
tim
e (G
yr)
Kasting et al. 1993
1 bar of CO250 mbar of CO20,3 mbar of CO2
CO2 greenhouse effect not anymore efficient
water escape
Sol
ar lu
min
osit
y
Evolution of the Habitable Zone
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CH4 required for surface liquid water
present CO2
CO2 > present CO2
O2 < 1 % present O2 O2 > 15 % present O2
Evolution of the Sun
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H2O
CONONO2
CO2
SO2CH4
H2O
?
?
4.5 Gyrt
?
Venus
Earth
Mars
O3
CO2
CO2
CO2H2O
Evolution of the Planets
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Darwin - the search for biospheres
...many questions to answerbeforeduring
and after...
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DARWIN
6 Telescopes (Free Flyers) 1 Hub (Beam Combiner)1 Master satellite
IRSIInfraRed
Space Interferometer
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ESA-Mission
• Launch: Ariane-5
• Orbit (Sun-Earth): L2
• Minimum Lifetime: 5 yr
• Monolitic reflectors: 6 (1.5 - 3 m)
Darwin - the search for biospheres
December 14, 2001MISU Page 32
Orbit of DARWIN
toward the
Sun
toward the
Sun
500.000 km
top view
side view
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Technical Requirements
• DARWIN shall provide (better than)
• Nulling factor: 105
• Base line accuracy : 1 cm
• Optical Path Difference : 20 nm
• Telescope pointing : 24 mas
• Amplitude accuracy : 10-2
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Time Line
20012005
Technical Development
2007
Definito
n Phase
Dem
o f
ligh
t: S
MA
RT
2
Building Phase
2013
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Darwin - the search for biospheres
Conclusions
DARWIN is an esa Cornerstone missionto detect & analyse Earth-like planets
- space precursor(s): SMART2 ( and 3?)- esa/eso groundbased Nuller @ VLT
Analysis needs atmosphere models