DARWIN The InfraRed Space Interferometer
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Transcript of DARWIN The InfraRed Space Interferometer
DARWINThe InfraRed Space Interferometer
Status of exo-planet searchStatus of exo-planet search• Stars (Solar type) observed: +3000 • Planets detected: ~ 86• Radial velocity measurement precision
– 1-2 m/s intrinsic limit?– Earth requires 0.1 m/s
Occultation:Planet orbiting HD209458P = 3.5 days
m = 0.7 Mjup
Rp = 1.4 Rjup
Status of exo-planet searchStatus of exo-planet search
Search For Extrasolar PlanetsSearch For Extrasolar Planets COROT
• COROT has two main scientific programs working simultaneously on adjacent regions of the sky:
• ASTEROSEISMOLOGY • SEARCH FOR
EXTRASOLAR PLANETS (“Super-Earths”- if they exist!)
Search For Extrasolar PlanetsSearch For Extrasolar Planets EDDINGTON
• Habitable Planets
• Jupiter /Sun =1 %
• Earth/ Sun = 8.4*10-5
• Mars/Sun = 3*10-5
• Photometric precision require space mission
> EDDINGTON determines minimum size of DARWIN
Direct detection of nearby EarthsDirect detection of nearby EarthsTwo major difficulties:
1. Contrast: 107 in the infrared for a Sun-Earth system
2. Angular Separation: 0.1 arcsec for a Sun-Earth system at 10pc
7
106
Dynamic range and resolution
Searching for nearby EarthsSearching for nearby Earths
Candle light 0.3m from lighthouse at a distance of
1000km
Light is drenched in radiation from
the star
interferometerinterferometer
Recomb.
Tele-scope
1
Tele-scope
2
Dsin
NullingNulling
Principle of a Bracewell nulling interferometer
Pupil plane recombination no image(the only thing we detect is an integrated flux)
bright output
dark output
20 m
500
mill
i-ar
csec
Transmission map
NULLING INTERFEROMETRYNULLING INTERFEROMETRY
0
The InfraRed Space InterferometerDARWIN
• 6 telescopes (1.5m)
• Hexagonal configuration
• Beam combiner
• Passive cooling (40 K)
Concept• Infrared interferometer
– Multi-aperture : 1.5 m telescopes baselined– Laurance class configuration– Wide band spectroscopy
• Free-flyer– Micropropulsion– Laser & RF metrology
• Wavefront filtering– Enabling technology – relaxes requirement
on WF qualitiy
The InfraRed Space InterferometerDARWIN
The Solar system as viewed from 10 pc on the 1:st of January 2001 with the Darwin baseline system
Venus
Mars
Earth
Nulled Sun
Characterizing nearby Earth’s
• We thus not only want to detect planets similar to ours but also characterize them from the light they produce
Characterizing EarthsCharacterizing EarthsCalculated atmospheric
spectra (= 200)
Photo
n m
-2
s-1
0
2
4
6
8
10CO
2
6 8 10 15 20 m
300K BB
0
2
4
6
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10O
3 (telluric)
6 8 10 15 20 m
0
2
4
6
8
10 H20
Observed spectra
0
2
4
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10
Earth
H2O O3 CO2
6 8 10 15 20 m
Mars (x 4)
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4
2
0
6
0
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4
6
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10 Venus (x1.5)
Search for exo-life
• What is life? contains information
can self-replicate
can evolve
• Life on Earth as a reference:
Carbon (organic) chemistry in watersolution
• Goal 2: Astrobiology
Search for exo-lifeSearch for exo-life• Attempt to detect life by remote sensing. Probably one of the most difficult problems in observational astronomy…
• Most likely criterion is simultaneous presence of liquid H2O together with presence of O2
1. O2 produced by life
2. O2 very reactive gas / rocks… if not continuously
produced it vanishes in < million yrs
3. O3 better than O2. It is logaritmically dependant on
amount of O2+ spectral lines in the IRPresence of O3 = signature of life
unless non-biotic production
Search for exo-life
- for > 20 yrs, no abiotic production of O3 found when:
• O3 with liquid H2O• atmosphere at T ~ 270 K (Habitable Zone)
• Qualifying the H2O / O 3 criterion:
If criterion stands, organic life can be searched for
NASA’s Terrestrial Planet Finder
Four 3.5m telescopes
Identical objectives to Darwin
Good basis for future collaboration