darwin in space the quest for life beyond the solar system
DESCRIPTION
DARWIN in SPACE The Quest for LIFE beyond the Solar System. Stockholm Observatory (6th floor). Contributors. Very Many People. Robin Laurance [1999] Jean-Marie Mariotti [1998]. Announcement. Towards Other Earths 22 – 25 April 2003 Heidelberg, Germany - PowerPoint PPT PresentationTRANSCRIPT
DARWIN SCFAB 21 November 2002 page: [email protected]
DARWIN in SPACE
The Quest for LIFE beyond the Solar System
Stockholm Observatory (6th floor)
DARWIN SCFAB 21 November 2002 page: [email protected]
Contributors
Announcement
Robin Laurance [1999]Jean-Marie Mariotti [1998]
Very Many People...
Towards Other Earths22 – 25 April 2003
Heidelberg, Germanyweb page: www.mpia.de/DARWINe-mail: [email protected]
DARWIN SCFAB 21 November 2002 page: [email protected]
Outline
Interdisciplinary Talk Astrophysics Biology Chemistry Philosophy...
Introduction - Formation of Stars and Planets
Scientific GoalsStatement of the Problem
Adopted SolutionCurrent Developments and Implementation
Look into the Future
DARWIN SCFAB 21 November 2002 page: [email protected]
DARWIN
… is a vessel
Detecting and Analysing Remote Worlds with Interferometric Nulling
DARWIN SCFAB 21 November 2002 page: [email protected]
DARWIN SCFAB 21 November 2002 page: [email protected]
Theory of Star & Planet Formation
1 AU = 150 Million km
1 pc = 200 000 AU
1 pc = 3 lightyears
*
*
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Hubble Space Telescope
protoplanetary disk+
hidden star
supersonic plasma jet
Observational Evidence - Newly Formed Star
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Observational Evidence for exo-Planets
P = 1 yr Earth: 100 000 km/h Sun: 0.3 km/h
M sin i
1 AU
Observing the STARS
DARWIN SCFAB 21 November 2002 page: [email protected]
Observational Evidence for exo-Planets:observing the Stars
1995: THE Breakthrough – 51 Peg
Mayor & Queloz 1995Nature 378, 355
100
50
0
-50
-100
V (m/s)
Phase 0 0.5 1
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Observational Evidence for exo-Planets:observing the Stars
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HD 209458 - HST I (%)
100
99
98
-0.1 0.0 0.1t – t0 (days)
Observational Evidence for exo-Planets:Observing the Stars
Planetary Hypothesis = truePlanetary Mass = 0.7 MJupiter
Planetary Radius = 1.4 RJupiter
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2002
>100 exos
M = O(MJupiter)
``Hot Jupiters´´
http://exoplanets.org/
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Mass Distribution Function of Exos
=> Existence of Many Earth-like ?
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Radial Velocity Technique
...does not provide this
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Stating the GOALS
[ 1 ] find Earth like Planets
[ 2 ] look for signs of Life
?...piece of cake...?
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[ 1 ] Finding exo-Earths
Different Stellar Temperatures – needs Variable Resolution
Short Lifetime
Brown Dwarfs
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[ 2 ] Identifying LIFE
What does ALL Life DO?
Life Produces WASTE !
Origin of Life?Definition of Life?
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Statement of the Problem
Earth like planet ?
with LIFE?
51 Pegasi
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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: [email protected]
Selection of Spectral Region
Scattered StellarRadiation
PlanetaryThermal Emission
Visible InfraRedlog 10
=> Space!
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Selection of Observational Method
Two (known) possibilities:
• New Concept
“Nulling’’ Interferometer in Space
Telescopes = 1.5 - 3.5 m Base Lines = 30 - 500 m Feasible!
• Coronograph in Space Telescope > 30 m NOT Realistic!
this is it!
DARWIN SCFAB 21 November 2002 page: [email protected]
Interferometry
We gain resolution... So, what do we loose?
Image information content
DARWIN SCFAB 21 November 2002 page: [email protected]
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/Bin coherent field of view 1/d
Example: = 10 m, B = 200 m, d = 2 mResolution = 10 milliarcsecField of view = 1 arcsec
DARWIN SCFAB 21 November 2002 page: [email protected]
simplest case: 2 element Bracewell
interferometer
Nulling Interferometer: Point Sources
``flat bottom´´High Rejection Rate: > 105
to ``null´´ stellar radiation e.g. at 10 pc distance Sun m10 m = 3.6 (1.6 Jy)*
Earth m10 m = 20.7 (0.23 Jy)
* 1 Jy = 10-26 W m-2 Hz-1
star on optical axis
= 0
=
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DARWINSimulation of Solar System
at 10 pc distance
Date: January 1, 2001 Ecliptic inclined by 30°
nulled Sun Venus Earth
Mars
Mennesson & Mariotti (1997)
WHAT is observed (1) Multi-Epoch Imaging
Discovery of Earth like exo-Planets
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WHAT is observed (2) Spectroscopy
IR Spektra – Fingerprints of the Planets
6 8 10 15 20 m
CO2CH4
H2OO3
….
• IR emission: 300K BB
continuum radiation
• IR absorption:
spectral lines
Physics & Chemistry of Planetary Atmospheres
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The Living Atmosphere
THE BIOmarkers!
6 8 10 12 14 16 18
CO2
H2O
H2O
O3
Wavelength (m)
Intensity Sagan et al. 1993 Nature 365, 715
Venus, Earth & Mars
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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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Oxygen Production = Life?same processes that produce abiotic O2
destroy O3 (radicals from H2O photolysis)or
mask the O3 signature (CO2 absorption)
Claim: photochemistry CANNOT reproducetriple signature of oxygen photosynthesis
O3 - CO2 - H2O Selsis et al. 2002, Astron. & Astrophys. 388, 985
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DARWIN
2 Three-DACs (Laurance)=
6 Telescopes (Free Flyers) 1 Hub (Beam Combiner)
+1 Master Satellite
IRSIInfraRed
Space Interferometerwww.esa.int/home/darwin/
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Orbit of DARWIN @ Sun-Earth L2
toward the
Sun
toward the
Sun
500.000 km
top view
side view
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Noise Control - Backgrounds
Stellar Leaks
Zodiacal Background
Exo-Zodi
Photon Noise from Planet
DARWIN SCFAB 21 November 2002 page: [email protected]
Noise Sources
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Target Selection
(t int) Stellar Leak ~ LStar D2 RPlanet- 4
optimised systems: - Low LStar : Cool Stars (M, K)
- Nearby: < 100 pc
- Big Planets: > 0.1 RTellus
- Not in (close) Stellar Binaries
• Angular Resolution (for planet in Habitable Zone)
Planet = 100 (LStar / LSun)1/2 (1/D10pc) [mas]
adjustable configuration (unresolved stellar disk)
• Signal-to-Noise (S/N)
DARWIN SCFAB 21 November 2002 page: [email protected]
some Major Performance Requirements
Nulling of on-axis-Star > 105
Baseline Accuracy 1 cm (rms)Optical Path Difference 20 nm (rms)Telescope Pointing 24 mas (rms)
Amplitude Matching < 10-2
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Ongoing Developments & Future Planning
Joint Mission 22 april 2002
GENIE (VLTI) 2003
SMART-2 (ff, metrol) 2006
COROT (occultation) 2004
Eddington (occult.) 2008Kepler (NASA) 2009
JWST (``NGST´´) 2010
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Ongoing Developments & Future Planning
Launch on Ariane-5 5E/CB 2013 - 2015
Conclusions:[1] find exo-Earths[2] find signs of Life
Darwin can do it!
DARWIN SCFAB 21 November 2002 page: [email protected]
DARWIN SCFAB 21 November 2002 page: [email protected]
Towards Other EarthsDarwin/TPF and the Search for Extrasolar Terrestial Planets
22 – 25 April 2003Heidelberg, Germany
web page: www.mpia.de/DARWINe-mail: [email protected]
DARWIN SCFAB 21 November 2002 page: [email protected]
DARWIN SCFAB 21 November 2002 page: [email protected]
The End
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Hydrodynamics of Star Formation
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Earth and Cows
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DARWIN SCFAB 21 November 2002 page: [email protected]
CO
CO2
UV
O2
O
UV
H2O
O
H
O2
OH
esca
pe
CO
CO2
UV
O2
O
abiotic=
photochemical O2
production
DARWIN SCFAB 21 November 2002 page: [email protected]
Abotic Production of O2 by H2O Photolysis
CO2
O3
H2O H2O
Inte
nsi
ty
Wavelength (m)
Selsis et al. 2002, Astron. & Astrophys. 388, 985
DARWIN SCFAB 21 November 2002 page: [email protected]
2H2O + CO2 + h CH2O + O2 + H2O
the oxygen producersthe oxygen producers
oxygenic photosynthesis :
CyanobacteriaCyanobacteria
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The late Rise of Oxygen(2.2-1.9 Gyrs ago)
Holland, 1993
PO2 < 1 % P.A.L PO2 > 15 % P.A.L
3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.6 0.8
Time (Gyrs)
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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
Temporal evolution of the Habitable Zone
DARWIN SCFAB 21 November 2002 page: [email protected]
CH4 required for surface liquid water
present CO2
CO2 > present CO2
O2 < 1 % present O2 O2 > 15 % present O2
Temporal evolution of the Sun
DARWIN SCFAB 21 November 2002 page: [email protected]
H2O
CONONO2
CO2
SO2CH4
H2O
Temporal Evolution of the Planets
?
?
4,5 Gyrst
?
Venus
The Earth
Mars
O3
CO2
CO2
CO2H2O
DARWIN SCFAB 21 November 2002 page: [email protected]
Beam Combination (1)
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Beam Combination (2)
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Beam Combination (3)
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Beam Combination (4)
50/50 beamsplitter
v
11/89 beamsplitter
DARWIN SCFAB 21 November 2002 page: [email protected]
Telescope Flyers
DARWIN SCFAB 21 November 2002 page: [email protected]
Telescope Optical Design
Transfer optics
Field stop
1.5 m primaryWide Field Camera
DARWIN SCFAB 21 November 2002 page: [email protected]
Beamcombiner (1)
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Beamcombiner (2)Optical bench Receiver telescopesBeam splitters
Amplitude matching deviceDelay lines
DARWIN SCFAB 21 November 2002 page: [email protected]
Noise Sources• Example:
Earth & Sun at 10 pc, = 10 m, =
20
background noise must be controlled
e- s -1 channel -1
Planet 0.14
Solar Zodi 140
Exo-Zodi 45
Stellar leaks 30 105 /
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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
DARWIN SCFAB 21 November 2002 page: [email protected]