Exobiology, also sometimes known as Astrobiology, aims to:

detect the presence or the evidence of a possible extraterrestrial life on celestial bodies in our Solar System and beyond;
explain the "extraterrestrial" part of the origine of life on Earth;

the contribution of the organic matter of interplanetary origin in the constitution of the primitive terrestrial organic matter;
the contribution of the organic matter of interplanetary origin to the apparition of life;
the conditions that prevailed during the first billion years of the Earth's formation and evolution.

detect the existence of a prebiotic chemistry potentially leading to the first steps of life on bodies of the Solar System.

Mars (© ESA) - Io (© NASA) - Titan (© ESA/NASA/Univ. Arizona)

To reach such a goal, contributions from numerous scientific fields such as chemistry, biochemistry, molecular genetics, geology, astronomy in all its variants, artificial life, etc. are needed. The CNRS interdisciplinary programme dedicated to the planetary environment and the origin of life is a major component of this interdisciplinarity.

In its space component, Exobiology interacts with Planetology (characterization of planets, definition of the notion of habitability, search for water and organic matter, interplanetary chemistry, etc.), Astronomy (search and characterization of exoplanets, definition of the evidence of a biological activity), and the robotic and human exploration of the Solar System (use of infrastructures for experiments, preparation of human missions in the Solar System and management of their effects in order to preserve the later search for traces of life).

The considerations on the search for traces of life in the Solar System, and the possible sample return from celestial bodies that could have hosted life, impose, in accordance with the international treaties on extra-atmospheric space, an important interaction between Exobiology and all activities included in the generic term of planetary protection

TECHNICAL REQUIREMENTS OF SPACE MISSIONS IN THE FIELD OF EXOBIOLOGY

Space missions in the fields of Planetology as well as Exobiology are based on the usual foundations that are remote observation, in-situ analysis and sample return. The technical requirements thus involve these three aspects. The perspective of a spectral analysis of the atmosphere of extrasolar planets encourages the work carried on models and on defining the evidence of a metabolic activity..

Remote analysis (remote observation)

The missions competing for the Cosmic Vision selection (for example Marco Polo, Plato, Laplace, Tandem etc.) include spectroscopic observations of the targeted celestial bodies. Improving the definition and sensitivity of the instruments, especially in the infrared domain, still represent major challenges. Some R&T actions (mainly in the field of Planetology) have begun in this domain as well as on improving the colour imaging capabilities. These remote analyses have reached a good level of maturity.

In-situ analysis

The in-situ analysis is the objective of several future missions and the improvement of the technologies used goes hand in hand with the miniaturization of the systems. Several R&T actions have already been undertaken in this domain to develop new performances (chirality analysis, mass spectrometry, molecular recognition) or to improve principle performances already engaged in missions (derivatisation). More prospective work is being done on the non-destructive analysis of samples brought back to Earth (Para Electronic Resonance: PER). The possibility of these techniques being used in space missions is also under study. At present, the experiments on the exposition of molecules or samples to space conditions on board the ISS require bringing back the samples to Earth to analyse them. Instruments built for the continuous analysis of samples outside the ISS during their exposition, or on board other spacecrafts, are under definition. Experiments using these techniques are being investigated in the hypothesis of a permanent scientific remote presence on the Moon. In many configurations, the progress already made on the spectral analysis and the imaging used for remote sensing benefits to spectro-imaging microscopes based on the same general principles.

Samples analysis on Earth

French laboratories have already been involved in the analysis of extraterrestrial samples brought back to Earth (Moon, Genesis and Stardust missions). The French community is also very involved in the analysis of meteoritic samples and interplanetary dust. R&T work on PER and studies on an airtight container for the analysis (using synchrotron radiation) of samples kept in confinement are paving the way. More work is required to design and operate, as part of a European programme, a Martian sample conservation and analysis centre, while respecting the recommendations on planetary protection as well as the constraints on the conservation conditions of the samples, as established by the Planetology and Exobiology scientific communities.

The scientific and technical skills of the French laboratories

The French community in the fields of Exobiology and Planetology is one of the biggest in Europe. It is also one of the most organized, mainly orbiting around three actors.

1. CNES played a trigger role by supporting the formation of a community already involved in space missions carried under the theme of Planetology.
2. The research group in Exobiology (GdR Exobio) which began to bring together scientists working far from space experimentation. It grouped communities which were far from the research on the origins of life and extra-terrestrial life. This GdR established the theoretical framework in which instrumental research and developments occur. This activity was magnified by the Exobiology Schools aimed at researchers (Ecole de Propriano) and those aimed at thesis students (Rencontre exobiologique pour Doctorant du Teich), organized by CNRS with the help of universities as well as CNES. This GdR became the CNRS interdisciplinary programme which covers many aspects of Exobiology with the open intent of involving other fields such as Life Sciences, Chemistry, Social Sciences, etc...
3. A scholar society, the French Exobiology Society (SFE) which brings together French scientists working in this domain. It aims to organize the reflections of the scientific community, to be the partner of similar international organisations such as the European Astrobiology Network Association (EANA) or the International Society for the Study of the Origin of Life (ISSOL).

The influence of the Ecole de Propriano in the French speaking world, and the referenced publications in English and French that stemmed from it, gave visibility and international acknowledgment to the French teams. The evolution of the structures and the generational turnover of the researchers involved justify the efforts to enhance the results already obtained and prepare the next international stepping stones linked to Mars sample return and the characterization of exoplanets.

CNES Involvement

Participation in the exploitation programme of the ISS and its associated means (Photon, Bion, parabolic flights).
Participation to missions such as Exomars, Marsnet, Mars Sample Return as part of the exploration programme.
Participation in some phases of the different scenarios of Moon use as a demonstration platform and in the hypothesis of a permanent remote presence in relation with the exploration programme.
Participation in Cosmic Vision, ESA's mandatory programme, in mission scenarios such as Marco Polo, Laplace, Tandem, Plato.
Development of opportunity missions and cooperation in preparatory work within the framework of the bilateral cooperation with the USA (Moon, Mars), Russia (Phobos-Grunt), China (Exposition in low orbit experiments, Moon) and others such as Japan, India...
Participation in studies, and in the realisation and operation of ground infrastructures as part of multilateral, European and ESA cooperations.

THE CURRENT, PLANNED AND POSSIBLE MISSIONS IN RELATION WITH THE EXOBIOLOGY FIELD

Current missions

CASSINI-HUYGENS:
Even though its atmospheric composition is different from the one proposed in the primitive Earth atmosphere models, Titan's atmosphere is home to a number of physical and chemical processes which resemble processes that may have happened on the primitive Earth. To explore Titan now, liquid water excluded, is to observe the influence of the space environment on a chemical reactor producing complex organic compounds from simple componants. The French scientific community was particularly active in supplying instruments for the Huygens probe and in the interpretation of the data collected. The "Exobiology interdisciplinary scientist" activity for the whole Cassini mission led by a French scientist also put forward the other French participations in the instruments of the Cassini probe whose mission has been extended until 2017.

ROSETTA:
The comets were formed in the early stages of the Solar System, but unlike planets, they have probably kept unspoiled the primitive material of the solar nebula. It is one of the main results from the analysis of the samples brought back by the Stardust mission to which the French scientific community contributed. The comets are considered as "archives" that witnessed the physicochemical conditions which prevailed 4.6 billion years ago. All the observations tend to show a great diversity and complexity in their molecular composition, making them an exceptional study field for Exobiology. Thanks to Rosetta, for the first time, we will have direct information on the molecular composition of the comet's core. We will better know to which extent the comets, by bringing more or less complex prebiotic blocks, may have contributed to the appearance of life on Earth.

MARS EXPRESS:
Mars Express was launched on June the 2nd, 2003. Since then, the mission has been extended until the end of 2012. The French scientific community supplied two scientific instruments and contributed to a third one: OMEGA (Observatoire Martien pour l'étude de l'Eau pour les Glaces & l'Activité), SPICAM (SPectroscopy for the Investigation of the Characteristics of the Atmosphere or Mars) and a participation to the development of ASPERA-3 (Analyser of Space Plasmas & EneRgetic Atoms).
All these instruments have been designed to answer scientific questions that go beyond Exobiology. Nonetheless the Exobiology community is highly interested by the results as they help them prepare the next missions (EXOMARS and MSR).

ISS/EXPOSE E & R (ESA's ELIPS PROGRAMME):
This instrument which exposes samples to solar radiations, microgravity, the void andcosmic rays, was built and is used as part of ESA's ISS use programme. This instrument hosts experiments of European scientists and in particular French teams. With the docking on February 11, 2008 of the Columbus laboratory to the ISS, ESA's EXPOSE E experiment, set on the EuTEF platform (European Technological Exposure Facility), was activated. Various solid and gaseous samples, including organic and non-organic products, some composed of biological elements, were exposed to solar radiations until August 2009. The EXPOSE R equipment which hosts other samples was fastened to the Russian module Zvezda in March 2009, and will be brought back to Earth in late 2010.

Planned missions

MSL:
Mars Science Laboratory (MSL) is a NASA mission which aims to land a vehicle of about 900 kg on Mars, equipped with ten mini-laboratories each made up of analytical instruments.
MSL's launch is scheduled for autumn 2011 and it should begin operations in 2012. Its main objectives are to:

determine whether life ever arose on Mars,
characterize the climate of Mars,
characterize the geology of Mars,
prepare for human exploration.

EXOMARS:
The EXOMARS programme is based on a strengthened cooperation with NASA and is composed of one orbital mission in 2016 and one surface mission in 2018.

For the 2016 mission, ESA is designing and building a Martian satellite able to ensure communications between its orbit and the Earth. It will also be able to receive and transmit signals from stations and vehicles on the surface until 2022 (nominal duration). This Martian satellite will carry a scientific payload of about 110 kg to study trace gases in the Martian atmosphere (methane and other hydrocarbons), and map them.
It will also act as a transfer system between the Earth and Mars for a European Mars landing demonstrator of about 600 kg. This fixed demonstration station will carry instruments to collect and send the data acquired during the descent and up to the landing. A limited scientific payload will be selected. It has a limited lifetime (about one week) and its power supply will be extremely limited. This mission will be launched by an American launcher (Atlas V type). The mission will be under ESA responsibility.

For the 2018 mission Europe will supply a surface vehicle carrying the Pasteur payload dedicated to the study of the geological context and to the search of potential traces of life. The Unites States will also supply a surface vehicle. The two vehicles will share the same platform delivered to the ground by a skycrane descent system. They will thus land at exactly the same location. The Pasteur payload includes two instruments managed by French laboratories (Wisdom and Micromega) and three instruments with strong French technical contribution (RAMAN, MOMA and CLUPI).
This mission will be launched by an American launcher (Atlas V type). The mission will be under NASA responsibility, ESA will be responsible for its surface vehicle after the landing. The 2016 Martian satellite will relay the data from the two surface vehicles.

ICAPS AND IPE (ISS):
A French team participates in the development of an instrument studying the properties and the behaviour of dust and ice particles. This instrument called ICAPS (Interactions of Cosmic and Atmospheric Particle Systems) is scheduled to fly with the second generation of instruments of the ISS. A precursor instrument is under definition at ESA (ICAPS Precursor Experiment: IPE).
These experiments are at the crossroads between Planetology, Physics under microgravity and to some extent Exobiology. This field is particularly concerned by the organic chemistry that can occur inside interplanetary and cometary ice grains as well as by the means to characterize this chemistry.

Possible missions

VITRINE:
This instrument which would be set up on the external part of the Columbus module, would be made up of a cleanable and reusable "chemical reactor" able to receive gaseous mixes and/or solid matter exposed to the ultraviolet radiation from the Sun. A set of analysis systems would be able to realize composition analyses during the evolution of the mixes or the degradation of the molecules. Such sub-systems would be derived from instruments used in planetary space missions. Such an instrument could open the way for more ambitious instruments which could be landed on the Moon as part of a remote presence.

MARCO POLO:
This mission proposes to land on a geocruiser asteroid, to realize in situ analyses and to bring back samples. These studies contribute to the complete inventory of the chemical wealth of small bodies, asteroids, comets and fragments of comets, which form meteoroids, bolids, Stratospheric Interplanetary Dusts (SIDP), meteorites and micrometeorites. Exobiology is particularly interested in the analysis of volatiles and potential carbonated matter as well as by the computation of the isotopic ratio of elements such as carbon, nitrogen, oxygen, etc.

MARSNET:
This mission is now referred to as an intermediate between Exomars and Mars Sample Return (MSR). This ESA mission which would be developed in the framework of the Aurora Solar System exploration programme is still in its infancy. Exobiology is very interested in this potential mission which would prepare the selection of the sites of sample collection for the MSR mission.

MARS SAMPLE RETURN:
The MSR mission appears once more in the calendar of NASA's future missions and seems a logical step for ESA after Exomars and Marsnet. An international study group (I-Mars) was set up under the initiative of the main space agencies to sketch the architecture of such a mission. This study group reflects on a mission that could be launched between 2020 and 2025. It is in charge of defining a reference mission as well as identifying all the required technologies including those concerning the conservation and the processing of the samples after their return on Earth.

PLATO:
Plato is a mission of astro-seismology and detection of Earth-size telluric exoplanets. The characteristics of the stars and planets will be determined with a high photometric precision of the order of 1%. The age of the different systems observed will also be determined with a precision of a few hundreds of million, thus improving our knowledge of the evolution of planetary systems. Plato will also observe a very large number of stars with a lesser accuracy, probably multiplying by a factor ten the number of systems having exoplanets. The observation of stars with a magnitude lower than those that can be observed by CoRoT or Kepler will make the detection of Earth-size planets possible.
The extension of the planetary systems catalogue towards sets including modest size planets is essential to the search of planets susceptible of hosting life forms.

DARWIN:
This mission proposes to study exoplanets by analysing the composition of a part of their spectrum in the infrared. Such an analysis could lead to the detection of hints of a biological activity.
This mission would be made of a fleet of satellites in formation flying around the Lagrange point. The joint navigation of the satellites requires new technologies ensuring a sufficient precision to realize measurements in nulling interferometry. This mission could study systems and planets previously detected or detect new planets.
Even if this mission is still in a very preliminary stage, the definition and selection of the atmospheric hints of a biological activity requires theoretical work as well as laboratory experiments very early, which the international Exobiology community has already initiated.