1. Nigel J Mason Physics & Astronomy The Open University, UK.
Biosignatures on Exoplanets:
The Identity of Life”
Nigel J Mason
Physics & Astronomy
The Open University, UK.
ESF Exploratory Workshop, held at EPS Mulhouse, June, 2009
Follow up (joint with COST Action CM0805 ; The Chemical Cosmos) Open University, January 15-17, 2010

2. Exoplanets One of the most exciting advances in modern astronomy
Detecting and exploring ‘New Worlds’
Rapidly increasing data set

3. Exoplanets in the Solar Neighbourhood
65 light years

4. Detecting Life Remotely
Pale Blue Dot
Visible or IR radiation contain
spectral fingerprint of planet’s
surface or atmosphere:
look for BIOSIGNATURES
CO2

5. 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

6. 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 ?

7. 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

8. 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’

9. Terrestrial exoplanets
Magma Snowball Jurassic Early Mars Early Venus
Jungleworld Desertworld Waterworld Superearth

10. Earth-in-Time Atmospheres
Magma Hadean Archaean Proterozoic Snowball
Atmospheric Composition
Silicate CO2 CO2 N2 N2
Steam H2O N2 O2 O2
CO2

11. 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...)

12. Results from workshops
We agreed some ‘models’

13.  Biomarker abundances?
Archaean atmosphere
2.5 billion years ago
CO2 (x10,x100)
CH4 (x10)
O2 (x0.1, 0.01)
UV (x100)
Tsurface (30-80oC)
Photon flux = 83% modern
 Biomarker abundances?

14. Proterozoic atmosphere
2.2 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)

15. Snowball Earth atmosphere
CO2 (x10)
CH4 (x2)
O2 (x0.1, 0.01)
UV (x100)
 Biomarker abundances? (O3, N2O)

16. Jungleworld atmosphere
High vegetation emissions
High O2 (21-35%)
 Biomarker abundances? (O3, N2O)

17. Superearth atmosphere
Earth composition
Psurface e.g. 1bar, 2bar
 Biomarker abundances? (O3, N2O)

18. Results from workshops
Need to test ‘models’ with laboratory mimics
Can use existing apparatus that models Solar System planets
but too many scenarios….

19. 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 -

20. 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

21. Results/Future from workshops
Two model exoplanets
An Earth like exoplanet (a Super Earth) on which photosynthesis has established itself (with oxygen and ozone, N2O as biomarkers) and
a pre-photosynthetic world in which methanogens are prevalent (which may also be closer to an early Martian world).

22. 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

23. 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)

24. Acknowledgements Professor Ewa Suskiewicz (Co -Chair ESF Workshop)
For slides and comment
Dr Lee Grenfell DLR & TU Berlin

25. 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

26. Why Exploratory workshop ?
Bring together diverse communities (Very important).
Observations – yes but…
Origins of life, Earth observation, technical and crucially
Laboratory testing of models

27. 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.

28. Why Exploratory workshop ?
Past examples
Ultracold Chemistry workshop (new area in ) – led to Eurocore (Euroquam) and ITNs field now developing rapidly with cold molecules now very topical