[email protected] DARWIN SCFAB 21 November 2002 page: 1 DARWIN in SPACE The Quest for LIFE beyond the...

DARWIN SCFAB 21 November 2002 page: [email protected]

DARWIN in SPACE

The Quest for LIFE beyond the Solar System

Stockholm Observatory (6th floor)


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]


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

… is a vessel

Detecting and Analysing Remote Worlds with Interferometric Nulling


Theory of Star & Planet Formation

1 AU = 150 Million km

1 pc = 200 000 AU

1 pc = 3 lightyears

*

*


Hubble Space Telescope

protoplanetary disk+

hidden star

supersonic plasma jet

Observational Evidence - Newly Formed Star


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


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


Observational Evidence for exo-Planets:observing the Stars


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


2002

>100 exos

M = O(MJupiter)

``Hot Jupiters´´

http://exoplanets.org/


Mass Distribution Function of Exos

=> Existence of Many Earth-like ?


Radial Velocity Technique

...does not provide this


Stating the GOALS

[ 1 ] find Earth like Planets

[ 2 ] look for signs of Life

?...piece of cake...?


[ 1 ] Finding exo-Earths

Different Stellar Temperatures – needs Variable Resolution

Short Lifetime

Brown Dwarfs


[ 2 ] Identifying LIFE

What does ALL Life DO?

Life Produces WASTE !

Origin of Life?Definition of Life?


Statement of the Problem

Earth like planet ?

with LIFE?

51 Pegasi


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!


Selection of Spectral Region

Scattered StellarRadiation

PlanetaryThermal Emission

Visible InfraRedlog 10

=> Space!


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!


Interferometry

We gain resolution... So, what do we loose?

Image information content


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


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

=


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


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


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


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


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

2 Three-DACs (Laurance)=

6 Telescopes (Free Flyers) 1 Hub (Beam Combiner)

+1 Master Satellite

IRSIInfraRed

Space Interferometerwww.esa.int/home/darwin/


Orbit of DARWIN @ Sun-Earth L2

toward the

Sun

toward the

Sun

500.000 km

top view

side view


Noise Control - Backgrounds

Stellar Leaks

Zodiacal Background

Exo-Zodi

Photon Noise from Planet


Noise Sources


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)


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


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


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!


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]


The End


Hydrodynamics of Star Formation


Earth and Cows


CO

CO2

UV

O2

O

UV

H2O

O

H

O2

OH

esca

pe

CO

CO2

UV

O2

O

abiotic=

photochemical O2

production


Abotic Production of O2 by H2O Photolysis

CO2

O3

H2O H2O

Inte

nsi

ty

Wavelength (m)

Selsis et al. 2002, Astron. & Astrophys. 388, 985


2H2O + CO2 + h CH2O + O2 + H2O

the oxygen producersthe oxygen producers

oxygenic photosynthesis :

CyanobacteriaCyanobacteria


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)


-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


CH4 required for surface liquid water

present CO2

CO2 > present CO2

O2 < 1 % present O2 O2 > 15 % present O2

Temporal evolution of the Sun


H2O

CONONO2

CO2

SO2CH4

H2O

Temporal Evolution of the Planets

?

?

4,5 Gyrst

?

Venus

The Earth

Mars

O3

CO2

CO2

CO2H2O


Beam Combination (1)



50/50 beamsplitter

v

11/89 beamsplitter


Telescope Flyers


Telescope Optical Design

Transfer optics

Field stop

1.5 m primaryWide Field Camera


Beamcombiner (1)


Beamcombiner (2)Optical bench Receiver telescopesBeam splitters

Amplitude matching deviceDelay lines


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 /


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

[email protected] DARWIN SCFAB 21 November 2002 page: 1 DARWIN in SPACE The Quest for LIFE beyond the...

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