Exobiology

Group leader: Frances WESTALL

Understanding the origin and early evolution of life on Earth, and the search for life elsewhere

Exobiology – or astrobiology – is a multidisciplinary field that focusses on the origin of life on Earth and the possibility of life on other bodies of the Solar System and throughout the Universe. This research includes experimental study of the origin of organic molecules and the chemistry that led to their evolution toward complex structures (the first cells and genetic systems). Our studies also include the analysis of the oldest traces of life on Earth and strategies for the detection of potential traces of extraterrestrial life.

Research in the Exobiology Group of the Centre de Biophysique Moléculaire primarily focusses on:

1) Origins of prebiotic molecules and homochirality

The group conducts studies that seek to understand the formation and stability of organic molecules that may have contributed to the origin of life on Earth more than 4 billion years ago. This includes molecules that may have been brought in from space together with those that formed on Earth. Within this framework, the group studies the stability of amino acids in space conditions through the EXPOSE experiments aboard the International Space Station (ISS) and using meteorite impact simulations. Experiments on a wide range of molecules of interest are also conducted in the laboratory to simulate the effects of ionic and photonic irradiation conditions and atmospheric entry. This work is complemented by studies on chemistry in environmental conditions representative of the primitive Earth including the range of rocks and minerals available at that time.

2) Oldest traces of life

The group studies traces of life in the oldest well-preserved terrestrial sediments (3.5-3.2 billion-year-old rocks from the Archaean of Western Australia and South Africa) to obtain detailed information on primitive microbial ecosystems. This work provides a better understanding of the geological environment of the Earth at that time, primitive metabolic networks and the preservation of biosignatures. This work is based on a multi-scale approach (from the description of the global geological context to elemental analyses within fossil structures, that is, from the supra-kilometre to the sub-millimetric scale), and is multimodal, involving a wide range of scientific instrumentation (microscopy, spectroscopy ...).

3) Biosignatures and artificial fossilisation

The group also conducts geomicrobiology experiments to artificially fossilise microorganisms comparable both to those that might have existed on the early Earth and those that potentially existed on Mars and other bodies in the solar system. This work allows us to study the evolution of biosignatures (traces of life) during diagenesis (fossilisation and metamorphism) on a geological time scales. These results are essential to guide the detection of traces of life in ancient rocks and to prepare future missions dedicated to the search for extraterrestrial life on other planetary bodies, such as Mars.

4) Space exploration and the search for life on Mars and elsewhere in the solar system

The exobiology group is strongly involved in the scientific and instrumental aspects of the European/Russian ExoMars 2020 rover mission. The current director of the group, Frances Westall, and the former director of the group, André Brack, co-ordinated the definition of this mission. Frances Westall also leads biosignature work in the Landing Site Selection Committee and is Co-PI (principal investigator) of the CLUPI Instrument and Co-I of the RLS, Ma_MISS and PanCam instruments. The group is also involved in the scientific calibration and development of several instruments to optimise the acquisition and interpretation of data of exobiological/astroiological and geological interest.

The group created the world's first collection of analogue materials available to test future space instruments, particularly those that will be deployed on Mars: the International Space Analogue Rockstore (www.isar.cnrs-orleans.com). This collection contains rocks and minerals that have been described on other bodies of the solar system (basalts, clays, salts ...), or whose existence is very likely (quartz, mica, graphite ...). There are also Archaean terrestrial rocks containing traces of primitive life considered representative of potential traces of Martian life. In the absence of Martian rocks on Earth (except for Martian meteorites, which are both few and costly), these materials make it possible to develop protocols and test space instruments on representative samples at a lower cost.

 

Significant publications:

  • Dass A.V., Hickman-Lewis K., Brack A., Kee T.P. and Westall F. (2016) Stochastic Prebiotic Chemistry within Realistic Geological Systems. ChemistrySelect 1, 4906-926
  • Westall F., Foucher F., Bost N., Bertrand M., Loizeau D., Vago J. L., Kminek G., Gaboyer F., Campbell K. A., Breheret J. G., Gautret P. and Cockell, C. S. (2015) Biosignatures on Mars : What, Where, and How ? Implications for the Search for Martian Life, Astrobiology (2015) 15 (11) 998-1029 - doi : 10.1089/ast.2015.1374
  • Westall Fr., Campbell K. A., Bréhéret J. G., Foucher F., Gautret P., Hubert A., Sorieul S., Grassineau N. and Guido D. M. (2015) Archean (3.33 Ga) microbe-sediment systems were diverse and flourished in a hydrothermal context, Geology (2015) 43 (7) 615-618 - doi : 10.1130/g366461
  • Foucher F., Ammar M.-R. and Westall F. (2015) Revealing the biotic origin of silicified Precambrian carbonaceous microstructures using Raman spectroscopic mapping, a potential method for the detection of microfossils on Mars, Journal of Raman Spectroscopy 46, 873-879 - doi : 10.1002/jrs.4687
  • Bertrand M., Chabin A., Colas C., Cadène M., Chaput D., Brack A., Cottin, H. and WestallF. (2015) The AMINO experiment : exposure of amino acids in the EXPOSE-R experiment on the International Space Station and in laboratory, International Journal of Astrobiology (2015) 14 (1) 89-97 - doi : 10.1017/S1473550414000354
  • Orange F., Dupont S., Goff O., Le Bienvenu N., Disnar J.-R., Westall F. and Le Romancer M. (2014), Experimental fossilization of the Thermophilic Gram-positive Bacterium Geobacillus SP7A : A Long Duration Preservation Study, Geomicrobiology Journal (2014) 31 (7) 578-589 - doi : 10.1080/01490451.2013.860208
  • Westall F., Loizeau D., Foucher F., Bost N., Betrand M., Vago J. and Kminek G. (2013) Habitability on Mars from a microbial point of view, Astrobiology 13 (9) 887-897
  • Foucher F. and Westall F. (2013) Raman imaging of metastable opal in carbonaceous microfossils of the 700-800 Ma old Draken Formation, Astrobiology 13-1, 57-67
  • Bost N., Westall F., Ramboz C., Foucher F., Pullan D., Meunier A., Petit S., Fleischer I., Klingelhöfer G. and Vago J.L. (2013) Missions to Mars : Characterisation of Mars analogue rocks for the International Space Analogue Rockstore (ISAR), Planetary and Space Science. 82-83, 113-127
  • Westall, F. ; Cavalazzi, B. ; Lemelle, L. ; Marrocchi, Y. ; Rouzaud, J.-N. ; Simionovici, A. ; Salomé, M. ; Mostefaoui, S. ; Andreazza, C. ; Foucher, F. ; Toporski, J. ; Jauss, A. ; Thiel, V. ; Southam, G. ; MacLean, L. ; Wirick, S. ; Hofmann, A. l. ; Meibom, A. ; Robert, F. and Défarge, C. (2011) Implications of in situ calcification for photosynthesis in a 3.3 Ga-old microbial biofilm from the Barberton greenstone belt, South Africa, Earth and Planetary Science Letters 2011, 310, (3-4), 468-479