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DARWIN The InfraRed Space Interferometer

DARWIN The InfraRed Space Interferometer. Status 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 HD209458 P = 3.5 days

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DARWIN The InfraRed Space Interferometer

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  1. DARWINThe InfraRed Space Interferometer

  2. Status 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 HD209458 • P = 3.5 days • m = 0.7 Mjup • Rp = 1.4 Rjup

  3. Status of exo-planet search

  4. Search For Extrasolar PlanetsCOROT • COROT has two main scientific programs working simultaneously on adjacent regions of the sky: • ASTEROSEISMOLOGY • SEARCH FOR EXTRASOLAR PLANETS (“Super-Earths”- if they exist!)

  5. Search For Extrasolar PlanetsEDDINGTON • Habitable Planets • Jupiter /Sun =1 % • Earth/ Sun = 8.4*10-5 • Mars/Sun = 3*10-5 • Photometric precision require space mission • EDDINGTON determines minimumsize of DARWIN

  6. Direct detection of nearby Earths 7 106 Two 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 Dynamic range and resolution

  7. Searching for nearby Earths Light is drenched in radiation from the star Candle light 0.3m from lighthouse at a distance of 1000km

  8. Nulling interferometer Dsin p Tele- scope 1 Recomb. Tele- scope 2

  9. 20 m 500 milli-arcsec NULLING INTERFEROMETRY Principle of a Bracewell nulling interferometer bright output 0 p dark output Transmission map Pupil plane recombination  no image (the only thing we detect is an integrated flux)

  10. The InfraRed Space InterferometerDARWIN • 6 telescopes (1.5m) • Hexagonal configuration • Beam combiner • Passive cooling (40 K)

  11. 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

  12. The InfraRed Space InterferometerDARWIN Venus Nulled Sun Mars Earth The Solar system as viewed from 10 pc on the 1:st of January 2001 with the Darwin baseline system

  13. Characterizing nearby Earth’s • We thus not only want to detect planets similar to ours but also characterize them from the light they produce

  14. Characterizing Earths Observed spectra Calculated atmospheric spectra (l/Dl = 200) H2O O3CO2 Photon m-2 s-1 300K BB 6 810 15 20 mm 6810 15 20 mm

  15. Search for exo-life • Goal 2: Astrobiology • What is life? contains information can self-replicate can evolve • Life on Earth as a reference: • Carbon (organic) chemistry in water solution

  16. Search for exo-life Presence of O3 = signature of life unlessnon-bioticproduction • 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 t < 10 million yrs 3. O3 better than O2. It is logaritmically dependant on amount of O2+ spectral lines in the IR

  17. Search for exo-life • Qualifying the H2O / O3 criterion: • - for > 20 yrs, no abiotic production of O3 found when: • O3 with liquid H2O • atmosphere at T ~ 270 K (Habitable Zone) If criterion stands, organic life can be searched for

  18. NASA’s Terrestrial Planet Finder Four 3.5m telescopes Identical objectives to Darwin Good basis for future collaboration

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