DARWIN SCFAB 21 November 2002 page: 1 [email protected] DARWIN in SPACE The Quest for LIFE beyond the Solar System Stockholm Observatory (6th floor)
Dec 21, 2015
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
*
*
DARWIN SCFAB 21 November 2002 page: [email protected]
Hubble Space Telescope
protoplanetary disk+
hidden star
supersonic plasma jet
Observational Evidence - Newly Formed Star
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
Observational Evidence for exo-Planets:observing the Stars
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
2002
>100 exos
M = O(MJupiter)
``Hot Jupiters´´
http://exoplanets.org/
DARWIN SCFAB 21 November 2002 page: [email protected]
Mass Distribution Function of Exos
=> Existence of Many Earth-like ?
DARWIN SCFAB 21 November 2002 page: [email protected]
Radial Velocity Technique
...does not provide this
DARWIN SCFAB 21 November 2002 page: [email protected]
Stating the GOALS
[ 1 ] find Earth like Planets
[ 2 ] look for signs of Life
?...piece of cake...?
DARWIN SCFAB 21 November 2002 page: [email protected]
[ 1 ] Finding exo-Earths
Different Stellar Temperatures – needs Variable Resolution
Short Lifetime
Brown Dwarfs
DARWIN SCFAB 21 November 2002 page: [email protected]
[ 2 ] Identifying LIFE
What does ALL Life DO?
Life Produces WASTE !
Origin of Life?Definition of Life?
DARWIN SCFAB 21 November 2002 page: [email protected]
Statement of the Problem
Earth like planet ?
with LIFE?
51 Pegasi
DARWIN SCFAB 21 November 2002 page: [email protected]
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!
DARWIN SCFAB 21 November 2002 page: [email protected]
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
=
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
DARWIN
2 Three-DACs (Laurance)=
6 Telescopes (Free Flyers) 1 Hub (Beam Combiner)
+1 Master Satellite
IRSIInfraRed
Space Interferometerwww.esa.int/home/darwin/
DARWIN SCFAB 21 November 2002 page: [email protected]
Orbit of DARWIN @ Sun-Earth L2
toward the
Sun
toward the
Sun
500.000 km
top view
side view
DARWIN SCFAB 21 November 2002 page: [email protected]
Noise Control - Backgrounds
Stellar Leaks
Zodiacal Background
Exo-Zodi
Photon Noise from Planet
DARWIN SCFAB 21 November 2002 page: [email protected]
Noise Sources
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
Hydrodynamics of Star Formation
DARWIN SCFAB 21 November 2002 page: [email protected]
Earth and Cows
DARWIN SCFAB 21 November 2002 page: [email protected]
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
DARWIN SCFAB 21 November 2002 page: [email protected]
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)
DARWIN SCFAB 21 November 2002 page: [email protected]
-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)
DARWIN SCFAB 21 November 2002 page: [email protected]
Beam Combination (2)
DARWIN SCFAB 21 November 2002 page: [email protected]
Beam Combination (3)
DARWIN SCFAB 21 November 2002 page: [email protected]
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)
DARWIN SCFAB 21 November 2002 page: [email protected]
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 /
DARWIN SCFAB 21 November 2002 page: [email protected]
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]