Nigel J MasonPhysics & Astronomy

The Open University, UK.

Biosignatures on Exoplanets: The Identity of Life”

ESF Exploratory Workshop, held at EPS Mulhouse, 23- 25 June, 2009

Follow up (joint with COST Action CM0805 ; The Chemical Cosmos) Open University, January 15-17, 2010

Exoplanets

• One of the most exciting advances in modern astronomy

• Detecting and exploring ‘New Worlds’

• Rapidly increasing data set

Exoplanets in the Solar Neighbourhood

65 light years

CO2

Detecting Life Remotely

Pale Blue Dot

Visible or IR radiation containspectral fingerprint of planet’ssurface or atmosphere:look for BIOSIGNATURES

Rationale of workshops

• Next decade will be able to detect/explore exoplanet atmospheres.

• Earth-like exoplanets will be detected in larger numbers.

• So how to look for signatures of life ?

First serious candidate for habitability: Gliese 581 d

Aims of workshops:

How to look for life of an exoplanet • What are the key

biomarkers/bio-indicators ?

• What are their spectroscopic signatures ?

• Are these detectable (with current means) ?

• Are they masked by abiotic signatures ?

Results from workshops• Identified possible

biomarkers with characteristic molecular spectra/fingerprints.

• Different biomarkers = different exoplanet scenarios.

• So need for composite molecular spectra in different atmospheres.

O2/O3

CH4

H2O

CO2

Results from workshops

• Need to model different scenarios

• Use Earth as benchmark for chemistry and HISTORY

• Research intricately linked to knowledge of ‘origins of life’

Magma Snowball Jurassic Early Mars Early Venus

Jungleworld Desertworld Waterworld Superearth

Terrestrial exoplanets

Earth-in-Time Atmospheres

CO2

Magma Hadean Archaean Proterozoic Snowball

Silicate CO2 CO2 N2 N2

Steam H2O N2 O2 O2

Atmospheric Composition

Factors affecting terrestrial atmospheres

Size, Mass (gravity, pressure)

Orbit (mean distance, eccentricity)

Central star (spectral type)

Atmospheric composition

(greenhouse gases, photochemistry)

Atmospheric mass (pressure)

Ocean (hydrological cycle)

Tectonics (volcanism, magnetism)

Age (Photon flux, evolution)

Biology (Emissions, CO2 cycle...)

Results from workshops

• We agreed some ‘models’

Archaean atmosphere2.5 billion years ago

CO2 (x10,x100)CH4 (x10)

O2 (x0.1, 0.01)UV (x100)

Tsurface (30-80oC)Photon flux = 83% modern Biomarker abundances?

Proterozoic atmosphere2.2 billion years ago

CO2 (x5)CH4 (x2, x5)

O2 (x0.1, 0.01)UV (x100)

Tsurface (30-80oC)Photon flux = ~90% modern

Biomarker abundances? (O3, N2O)

Snowball Earth atmosphere

CO2 (x10)CH4 (x2)

O2 (x0.1, 0.01)UV (x100)

Biomarker abundances? (O3, N2O)

Jungleworld atmosphere

High vegetation emissionsHigh O2 (21-35%)

Biomarker abundances? (O3, N2O)

Superearth atmosphere

Earth compositionPsurface e.g. 1bar, 2bar

Biomarker abundances? (O3, N2O)

Results from workshops

• Need to test ‘models’ with laboratory mimics

• Can use existing apparatus that models Solar System planets

• but too many scenarios….

Results from workshops

• Community needs to converge on one or two exoplanet models to test vs laboratory data.

• Choice may come from observations or

• May design an agreed exoplanet -

Results/Future from workshops

• Workshops follow up

• Develop design of an agreed exoplanet for use in models and laboratory

• Use COST Action CM0805 to develop these scenarios further

Results/Future from workshops

• Two model exoplanets

(i) An Earth like exoplanet (a Super Earth) on which photosynthesis has established itself (with oxygen and ozone, N2O as biomarkers) and

(i) a pre-photosynthetic world in which methanogens are prevalent (which may also be closer to an early Martian world).

Follow up

• Through EU actions

• COST Action CM0805 (WG3) next meeting October 5-8 and December 5-7

• ITN Lassie and new one in January 2011

• VAMDC – research infrastructure

• Europlanet – well networked with Commission, ESA, EU Parliament

Publicity

• Planned exhibition in Brussels June 2011

• Combining COST Action, Lassie and Europlanet

• EU in Space exploration

• Briefing to FP, MEPS and others

(as part of International Year of Chemistry)

For slides and comment

Dr Lee Grenfell DLR & TU Berlin

Professor Ewa Suskiewicz

(Co -Chair ESF Workshop)

Why Exploratory workshop ?

• Reviewed options for different topics/requirements in 2008

• ‘Exploratory’ – New science – ‘out of the box’ – not mature field, not results now !

• So cant demonstrate ‘history’ – as in COST

Why Exploratory workshop ?

• Bring together diverse communities (Very important).

• Observations – yes but…

• Origins of life, Earth observation, technical and crucially

• Laboratory testing of models

Why Exploratory workshop ?

• How to be successful• Specific outcomes – ask specific question (get

multiple answers –not what we expected) • Presentation but discussion after each with

summary end of each session • Follow up critical – having identified need to

develop joint model could follow up and bring in other experts we found missing in workshop.

Why Exploratory workshop ?

Past examples

Ultracold Chemistry workshop (new area in 2004-5) – led to Eurocore (Euroquam) and ITNs field now developing rapidly with cold molecules now very topical