DARWIN SCFAB 21 November 2002 page: 1 DARWIN in SPACE The Quest for LIFE beyond the Solar System Stockholm Observatory (6th floor)

DARWIN SCFAB 21 November 2002 page: 2 Contributors Announcement Robin Laurance [1999] Jean-Marie Mariotti [1998] Very Many People... Towards Other Earths 22 – 25 April 2003 Heidelberg, Germany web page:

DARWIN SCFAB 21 November 2002 page: 3 Outline Interdisciplinary Talk Astrophysics Biology Chemistry Philosophy... Introduction - Formation of Stars and Planets Scientific Goals Statement of the Problem Adopted Solution Current Developments and Implementation Look into the Future

DARWIN SCFAB 21 November 2002 page: 4 DARWIN … is a vessel D etecting and A nalysing R emote W orlds with I nterferometric N ulling

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DARWIN SCFAB 21 November 2002 page: 6 Theory of Star & Planet Formation 1 AU = 150 Million km 1 pc = AU 1 pc = 3 lightyears * *

DARWIN SCFAB 21 November 2002 page: 7 Hubble Space Telescope protoplanetary disk + hidden star supersonic plasma jet Observational Evidence - Newly Formed Star

DARWIN SCFAB 21 November 2002 page: 8 Observational Evidence for exo-Planets P = 1 yr Earth: km/h Sun: 0.3 km/h M sin i 1 AU Observing the STARS

DARWIN SCFAB 21 November 2002 page: 9 Observational Evidence for exo-Planets: observing the Stars 1995: THE Breakthrough – 51 Peg Mayor & Queloz 1995 Nature 378, V (m/s) Phase

DARWIN SCFAB 21 November 2002 page: 10 Observational Evidence for exo-Planets: observing the Stars

DARWIN SCFAB 21 November 2002 page: 11 HD HST I (%) t – t 0 (days) Observational Evidence for exo-Planets: Observing the Stars Planetary Hypothesis = true Planetary Mass = 0.7 M Jupiter Planetary Radius = 1.4 R Jupiter

DARWIN SCFAB 21 November 2002 page: >100 exos M = O(M Jupiter ) ``Hot Jupiters´´

DARWIN SCFAB 21 November 2002 page: 13 Mass Distribution Function of Exos => Existence of Many Earth-like ?

DARWIN SCFAB 21 November 2002 page: 14 Radial Velocity Technique...does not provide this

DARWIN SCFAB 21 November 2002 page: 15 Stating the GOALS [ 1 ] find Earth like Planets [ 2 ] look for signs of Life ?...piece of cake...?

DARWIN SCFAB 21 November 2002 page: 16 [ 1 ] Finding exo-Earths Different Stellar Temperatures – needs Variable Resolution Short Lifetime Brown Dwarfs

DARWIN SCFAB 21 November 2002 page: 17 [ 2 ] Identifying LIFE What does ALL Life DO? Life Produces WASTE ! Origin of Life?Definition of Life?

DARWIN SCFAB 21 November 2002 page: 18 Statement of the Problem Earth like planet ? with LIFE? 51 Pegasi

DARWIN SCFAB 21 November 2002 page: 19 Possible Solutions – Possible Techniques Radial Velocity: NOT feasible (9 cm/s; contamination by convection and big planets) Astrometry: feasible from SPACE (<3  arcsec) Occultation: feasible from SPACE (<0.01%) Micro Lensing: single event (hours; little information) …needs observatories in SPACE!

DARWIN SCFAB 21 November 2002 page: 20 Selection of Spectral Region Scattered Stellar Radiation Planetary Thermal Emission VisibleInfraRed log 10 => Space!

DARWIN SCFAB 21 November 2002 page: 21 Selection of Observational Method Two (known) possibilities: New Concept “Nulling’’ Interferometer in Space  Telescopes = m  Base Lines = m  Feasible! Coronograph in Space  Telescope > 30 m  NOT Realistic! this is it!

DARWIN SCFAB 21 November 2002 page: 22 Interferometry We gain resolution...So, what do we loose? Image information content

DARWIN SCFAB 21 November 2002 page: 23 D B d/2 Filled aperture D: contains all spatial frequencies up to 1/D => Image of the source Interferometer B: picks out 1 spatial frequency 1/B in coherent field of view 1/d Example:  = 10  m, B = 200 m, d = 2 m Resolution = 10 milliarcsec Field of view = 1 arcsec

DARWIN SCFAB 21 November 2002 page: 24 simplest case: 2 element Bracewell interferometer Nulling Interferometer: Point Sources ``flat bottom´´ High Rejection Rate: > 10 5 to ``null´´ stellar radiation e.g. at 10 pc distance Sun m 10  m = 3.6 (1.6 Jy)* Earth m 10  m = 20.7 (0.23  Jy) * 1 Jy = W m -2 Hz -1 star on optical axis  = 0 =

DARWIN SCFAB 21 November 2002 page: 25 DARWIN Simulation of Solar System at 10 pc distance Date: January 1, 2001 Ecliptic inclined by 30° nulled Sun VenusEarth Mars Mennesson & Mariotti (1997) WHAT is observed (1) Multi-Epoch Imaging Discovery of Earth like exo-Planets

DARWIN SCFAB 21 November 2002 page: 26 WHAT is observed (2) Spectroscopy IR Spektra – Fingerprints of the Planets CO 2 CH 4 H 2 O O 3 …. IR emission: 300K BB continuum radiation IR absorption: spectral lines êPhysics & Chemistry of Planetary Atmospheres

DARWIN SCFAB 21 November 2002 page: 27 The Living Atmosphere THE BIOmarkers! CO 2 H2OH2O H2OH2O O3O3 Wavelength (  m) Intensity Intensity Sagan et al Nature 365, 715 Venus, Earth & Mars

DARWIN SCFAB 21 November 2002 page: 28 The Search for Biospheres Life on Earth as a reference: C-based chemistry in H 2 O solution ….produces Oxygen wavelength (  m) O2O2 O 2 + O + M  O 3 + M Oxygen Photosynthesis 2H 2 O + CO 2 + 8h  CH 2 O + O 2 + H 2 O O3O3

DARWIN SCFAB 21 November 2002 page: 29 Oxygen Production = Life? same processes that produce abiotic O 2 destroy O 3 (radicals from H 2 O photolysis) or mask the O 3 signature (CO 2 absorption) Claim: photochemistry CANNOT reproduce triple signature of oxygen photosynthesis O 3 - CO 2 - H 2 O Selsis et al. 2002, Astron. & Astrophys. 388, 985

DARWIN SCFAB 21 November 2002 page: 30 DARWIN 2 Three-DACs (Laurance) = 6 Telescopes (Free Flyers) 1 Hub (Beam Combiner) + 1 Master Satellite IRSI InfraRed Space Interferometer

DARWIN SCFAB 21 November 2002 page: 31 Orbit of Sun-Earth L2 toward the Sun toward the Sun km top view side view

DARWIN SCFAB 21 November 2002 page: 32 Noise Control - Backgrounds Stellar Leaks Zodiacal Background Exo-Zodi Photon Noise from Planet

DARWIN SCFAB 21 November 2002 page: 33 Noise Sources

DARWIN SCFAB 21 November 2002 page: 34 Target Selection (t int ) Stellar Leak ~ L Star D 2 R Planet - 4  optimised systems: - Low L Star : Cool Stars (M, K) - Nearby: < 100 pc - Big Planets: > 0.1 R Tellus - Not in (close) Stellar Binaries Angular Resolution (for planet in Habitable Zone)  Planet = 100 (L Star / L Sun ) 1/2 (1/D 10pc ) [mas] è adjustable configuration (unresolved stellar disk) Signal-to-Noise (S/N)

DARWIN SCFAB 21 November 2002 page: 35 some Major Performance Requirements Nulling of on-axis-Star > 10 5 Baseline Accuracy 1 cm (rms) Optical Path Difference 20 nm (rms) Telescope Pointing 24 mas (rms) Amplitude Matching < 10 -2

DARWIN SCFAB 21 November 2002 page: 36 Ongoing Developments & Future Planning Joint Mission 22 april 2002 GENIE (VLTI) 2003 SMART-2 (ff, metrol) 2006 COROT (occultation) 2004 Eddington (occult.) 2008 Kepler (NASA) 2009 JWST (``NGST´´) 2010

DARWIN SCFAB 21 November 2002 page: 37 Ongoing Developments & Future Planning Launch on Ariane-5 5E/CB Conclusions: [1] find exo-Earths [2] find signs of Life Darwin can do it!

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DARWIN SCFAB 21 November 2002 page: 39 Towards Other Earths Darwin/TPF and the Search for Extrasolar Terrestial Planets 22 – 25 April 2003 Heidelberg, Germany web page:

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DARWIN SCFAB 21 November 2002 page: 41 The End

DARWIN SCFAB 21 November 2002 page: 42 Hydrodynamics of Star Formation

DARWIN SCFAB 21 November 2002 page: 43 Earth and Cows

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DARWIN SCFAB 21 November 2002 page: 45 CO CO 2 UV O2O2 O H2OH2O O H O2O2 OH escape CO CO 2 UV O2O2 O abiotic = photochemical O 2 production

DARWIN SCFAB 21 November 2002 page: 46 Abotic Production of O 2 by H 2 O Photolysis CO 2 O3O3 H2OH2O H2OH2O Intensity Wavelength (  m) Selsis et al. 2002, Astron. & Astrophys. 388, 985

DARWIN SCFAB 21 November 2002 page: 47 2H 2 O + CO 2 + h  CH 2 O + O 2 + H 2 O the oxygen producers oxygenic photosynthesis : Cyanobacteria

DARWIN SCFAB 21 November 2002 page: 48 The late Rise of Oxygen ( Gyrs ago) Holland, 1993 P O2 < 1 % P.A.LP O2 > 15 % P.A.L Time (Gyrs)

DARWIN SCFAB 21 November 2002 page: ,51,52,53,51,02,03,0 AU time (Gyr) Kasting et al bar of CO 2 50 mbar of CO 2 0,3 mbar of CO 2 CO 2 greenhouse effect not anymore efficient water escape Solar luminosity Temporal evolution of the Habitable Zone

DARWIN SCFAB 21 November 2002 page: 50 CH 4 required for surface liquid water present CO 2 CO 2 > present CO 2 O 2 < 1 % present O 2 O 2 > 15 % present O 2 Temporal evolution of the Sun

DARWIN SCFAB 21 November 2002 page: 51 H2OH2O CO NO NO 2 CO 2 SO 2 CH 4 H2OH2O Temporal Evolution of the Planets ? ? 4,5 Gyrs t ? Venus The Earth Mars O3O3 CO 2 H2OH2O

DARWIN SCFAB 21 November 2002 page: 52 Beam Combination (1)

DARWIN SCFAB 21 November 2002 page: 53 Beam Combination (2)

DARWIN SCFAB 21 November 2002 page: 54 Beam Combination (3)

DARWIN SCFAB 21 November 2002 page: 55 Beam Combination (4) 50/50 beamsplitter v 11/89 beamsplitter 

DARWIN SCFAB 21 November 2002 page: 56 Telescope Flyers

DARWIN SCFAB 21 November 2002 page: 57 Telescope Optical Design Transfer optics Field stop 1.5 m primary Wide Field Camera

DARWIN SCFAB 21 November 2002 page: 58 Beamcombiner (1)

DARWIN SCFAB 21 November 2002 page: 59 Beamcombiner (2) Optical benchReceiver telescopes Beam splitters Amplitude matching device Delay lines

DARWIN SCFAB 21 November 2002 page: 60 Noise Sources Example: Earth & Sun at 10 pc,  = 10  m,  = 20  background noise must be controlled

DARWIN SCFAB 21 November 2002 page: 61 Noise Sources Example 2: sources:- shot noise from mean value - variation of instantaneous values e.g. stellar leaks:    leaks = [ 1/  I  + P (1/  ( o ) I   ]  t  shot noise Power Spectral Density

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