December 14, 2001MISU Page 1 DARWIN D etecting & A nalysing R emote W orlds through I nterferometric...

December 14, 2001MISU Page 1

DARWIN

Detecting & Analysing

Remote Worlds

through

Interferometric Nullinga vessel


Darwin - the search for biospheres

“Biosphere”

=

Planetary Atmosphere

+

Bioactivity



Do planets outside the solar

system exist?


Darwin - the search for biospheresHubble Space Telescope

HH 30 protoplanetary disk

HH 30supersonic plasma-jet



1995a

breakthrough



True mass & radius from...



…planetary transit observational proof!

Exoplanets do exist!HD 209458 - Hubble Space Telescope





Radial velocity survey:

observation of >3000 G-M starsabout 70 stars with exoplanets identifiedobservational limit: about 1 m/s

Similarities/differences wrt solar system(1) projected mass vs semimajor axis



Similarities/differences compared to solar system(2) eccentricities



Earth



Search for exosolar Earth-type planets

Radial velocities: <10 cm/s

Astrometry: <3 arcsec (10-11 rad)

Dynamic range: VIS 109

MIR 107



Search for exosolar Earth-type planetsRadial velocities: <10 cm/s

Astrometry: <3 arcsec (10-11 rad)

Dynamic range: VIS 109

MIR 107

log



Needs large telescope for resolutionand

“mask” for contrast

telescope 30 m … in space!



The masking device:a

Nulling Interferometerwith

rejection < 10-5



(2) to take IR-spectra of these x-tremely weak point sources

i.e. an instrument that is capable

(1) to image at high resolution x-tremely weak point sources



(1) to image at high resolution x-tremely weak point sources

DARWINSimulation of Solar System

at 10 pc distance

Date: January 1, 2001 Ecliptic inclined by 30°

nulled SunVenus Earth

Mars

Mennesson & Mariotti (1997)



(2) to take IR-spectra of these x-tremely weak point sources


Darwin - the search for biosphereslo

g



5 to 20 m region contains molecular bands

…bio-markers...6 8 10 12 14 16 18

CO2

H2O

H2O

O3



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



But what about...


CO

CO2

UV

O2

O

UV

H2O

O

H

O2

OH

esca

pe

CO

CO2

UV

O2

O

abiotic=

photochemical O2

production


Darwin - the search for biospheressame processes that produce abiotic O2

destroy O3 (radicals from H2O photolysis)or

screen the O3 signature (CO2 absorption)

Claim: photochemistry cannot reproducetriple signature of oxygen photosynthesis

O3 - CO2 - H2O



But what about time evolution...


-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

Evolution of the Habitable Zone


CH4 required for surface liquid water

present CO2

CO2 > present CO2

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

Evolution of the Sun


H2O

CONONO2

CO2

SO2CH4

H2O

?

?

4.5 Gyrt

?

Venus

Earth

Mars

O3

CO2

CO2

CO2H2O

Evolution of the Planets



...many questions to answerbeforeduring

and after...


DARWIN

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

IRSIInfraRed

Space Interferometer


ESA-Mission

• Launch: Ariane-5

• Orbit (Sun-Earth): L2

• Minimum Lifetime: 5 yr

• Monolitic reflectors: 6 (1.5 - 3 m)



Orbit of DARWIN

toward the

Sun

toward the

Sun

500.000 km

top view

side view


Technical Requirements

• DARWIN shall provide (better than)

• Nulling factor: 105

• Base line accuracy : 1 cm

• Optical Path Difference : 20 nm

• Telescope pointing : 24 mas

• Amplitude accuracy : 10-2


Time Line

20012005

Technical Development

2007

Definito

n Phase

Dem

o f

ligh

t: S

MA

RT

2

Building Phase

2013



Conclusions

DARWIN is an esa Cornerstone missionto detect & analyse Earth-like planets

- space precursor(s): SMART2 ( and 3?)- esa/eso groundbased Nuller @ VLT

Analysis needs atmosphere models




Life on Mars?


Life on Earth?


Telescope: Free Flyers

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December 14, 2001MISU Page 1 DARWIN D etecting & A nalysing R emote W orlds through I nterferometric...

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