Résumé L’exploration de la planète Mars et le retour d’échantillons martiens représentent de véritables défis non seulement scientifiques et techniques, mais également éthiques. Même si le risque de mettre en danger la vie sur Terre est estimé faible, vaut-il la peine d’être pris ?

In preparation for the upcoming sample return missions containing potential biohazards which may have withstood the rigors of space travel we present a hyperspectral method of in-situ analysis of grains combining several non-destructive imaging diagnostics, performed in BSL4 quarantine conditions. This offers an alternative to the analyses in facilities at large, using optimized experimental setups while keeping the samples in conditions of quarantine. Our methodology was tested during analyses of meteorites and cometary and interstellar grains from the recent NASA Stardust mission.

In accordance with the United Nations Outer Space Treaties [United Nations, Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, UN doc A/RES/34/68, resolution 38/68 of December 1979], currently maintained and promulgated by the Committee on Space Research [COSPAR Planetary Protection Panel, Planetary Protection Policy accepted by the COSPAR Council and Bureau, 20 October 2002, amended 24 March 2005, http://www.cosparhq.org/scistr/PPPolicy.htm ], missions exploring the Solar system must meet planetary protection requirements. Planetary protection aims to protect celestial bodies from terrestrial contamination and to protect the Earth environment from potential biological contamination carried by returned samples or space systems that have been in contact with an extraterrestrial environment. From an exobiology perspective, Mars is one of the major targets, and several missions are currently in operation, in transit, or scheduled for its exploration. Some of them include payloads dedicated to the detection of life or traces of life. The next step, over the coming years, will be to return samples from Mars to Earth, with a view to increasing our knowledge in preparation for the first manned mission that is likely to take place within the next few decades. Robotic missions to Mars shall meet planetary protection specifications, currently well documented, and planetary protection programs are implemented in a very reliable manner given that experience in the field spans some 40 years. With regards to sample return missions, a set of stringent requirements has been approved by COSPAR [COSPAR Planetary Protection Panel, Planetary Protection Policy accepted by the COSPAR Council and Bureau, 20 October 2002, amended 24 March 2005, http://www.cosparhq.org/scistr/PPPolicy.htm ], and technical challenges must now be overcome in order to preserve the Earth’s biosphere from any eventual contamination risk. In addition to the human dimension of the mission, sending astronauts to Mars will entail meeting all these constraints. Astronauts present huge sources of contamination for Mars and are also potential carriers of biohazardous material on their return to Earth. If they were to have the misfortune of being contaminated, they themselves would become a biohazard, and, as a consequence, in addition to the technical constraints, human and ethical considerations must also be taken into account.

The next time humans set foot on the Moon or another planet, will we treat the crew like we would a sample return mission when they come back to Earth? This may seem a surprising or even provocative question, but it is one we need to address. The hurdles and hazards of sending humans to Mars – for example, the technology constraints and physiological and psychological challenges – are many; but let us not forget the need to protect populations and environments from the risk of contamination [United Nations, treaty on principles governing the activities of states in the exploration and use of outer space, including the Moon and other celestial bodies (the “Outer Space Treaty”) referenced 610 UNTS 205 - resolution 2222(XXI) of December 1966].

What hazards might biological contamination pose to planets, comets and other celestial bodies visited by probes launched from Earth? What hazards might returning probes pose to Earth and its inhabitants? What should be considered an acceptable level of risk? What technologies, procedures and constraints should be applied? What sort of attitude has to be chosen concerning human crews, who themselves could become both contaminated victims and contaminating agents? The vast issue of planetary protection must, more than ever, spark ethical debate. Space treaty, COSPAR recommendations offer borders and context for this reflection, which has to be introduced in the actual humanist: never has been anthropocentrism so practical and concerned, in the same time, by the next generations, because of the historical character of life. At least an ethics of risk is necessary (far from the myth of zero-risk) for all the three types of contamination: other celestial bodies (forward contamination), Earth (backward contamination) and astronauts.

United Nations Space Treaties [ United Nations, Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, 610 UNTS 205, resolution 2222(XXI) of December 1966., United Nations, Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, UN doc A/RES/34/68, resolution 38/68 of December 1979. ] require the preservation of planets and of Earth from contamination. All nations part to these Treaties shall take measures to prevent forward and backward contamination during missions exploring our solar system. As observer for the United Nations Committee on Peaceful Uses of Outer Space, the COSPAR (Committee of Space Research) defines and handles the applicable policy and proposes recommendations to Space Agencies [COSPAR Planetary Protection Panel, Planetary Protection Policy accepted by the COSPAR Council and Bureau, 20 October 2002, amended 24 March 2005. http://www.cosparhq.org/scistr/PPPolicy.htm .]. The goal is to protect celestial bodies from terrestrial biological contamination as well as to protect the Earth environment from an eventual biohazard which may be carried by extraterrestrial samples or by space systems returning to Earth. According to the applicable specifications, including in our case the French requirements [ CNES, System Safety. Planetary Protection Requirements. Normative referential CNES RNC-CNES-R-14, CNES Toulouse, ed. 4, 04 October 2002. ], the prevention of forward contamination is accomplished by reducing the bioburden on space hardware to acceptable, prescribed levels, including in some instances system sterilization, assembling and integrating the appropriate spacecraft systems in cleanrooms of appropriate biological cleanliness, avoiding or controlling any recontamination risk, and limiting the probability impact of space systems. In order to prepare for future exploration missions [ Debus, A., Planetary protection: organization requirements and needs for future planetary exploration missions, ESA conference publication SP-543, pp 103–114, 2003. ], and in particular for missions to Mars requiring to control the spacecraft bioburden, a test program has been developed to evaluate the biological contamination under the fairing of the Ariane 5 launcher.

Since the beginning of solar system exploration, numerous spacecrafts have been sent towards others worlds, and one of the main goals of such missions is the search for extraterrestrial forms of life. It is known that, under certain conditions, some terrestrial entities are able to survive during cruises in space and that they may contaminate other planets (forward contamination). At another level, possible extraterrestrial life forms are unknown and their ability to contaminate the Earth's biosphere (back contamination) in the frame of sample return missions cannot be excluded. Article IX of the Outer Space Treaty (London/Washington, January 27, 1967) requires the preservation of planets and the Earth from contamination. All nations taking part in this Treaty must prevent forward and back contamination during missions exploring our solar system. Consequently, the United Nations (UN-COPUOS) has delegated COSPAR (Committee of Space Research) to take charge of planetary protection and, at present, all space-faring nations must comply with COSPAR policy and consequently with COSPAR planetary protection recommendations. Starting from these recommendations and the “CNES Planetary Protection Standard” document, a working group has been set up in the framework of the “European Cooperation for Space Standardization” (ECSS) to establish the main specifications for preventing cross-contamination between target bodies within the solar system and the Earth–moon system.

In line with the UN Outer Space Treaty (article IX of the Outer Space Treaty—London/Washington January 27, 1967) [United Nations Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (the “Outer Space Treaty”) referenced 610 UNTS 205—resolution 2222(XXI) of December 1966 [1] ] and with COSPAR recommendations, for ethical, safety and scientific reasons, exploration of the solar system needs to comply with planetary protection constraints in order to avoid extraterrestrial bodies contamination, particularly biological contamination by terrestrial microorganisms. It is also required to protect Earth from an eventual contamination carried by return systems or samples. The search for life in extraterrestrial samples, in situ or in the frame of sample return missions, must be conducted in order to state with the maximum possible confidence, because the discovery or the non-discovery of life in sample has a direct impact on updations of planetary protection specifications for future missions. This last requirement imposes consequently also for implementation in order to preserve extra terrestrial sample properties, protecting also indirectly exobiological science. These constraints impose to set up unusual requirements for project teams involved in such solar system exploration missions, requirements based on hardware sterilization, sterile integration, organic cleanliness, microbiological and cleanliness control, the use of high-reliability system in order to avoid crashes, the definition of specific trajectories and their control, recontamination prevention, etc. Implementation of such requirements induces costs, difficult to estimate, but which can be important depending on the solar system target and the mission definition (fly-by, orbiter or lander). The cost impact of a planetary protection program could be important if some basic rules are not taken into account enough early and consequently, upon past experience, some recommendations can be proposed here in order to manage properly such programs and to minimize their cost.

Since the beginning of the exploration of Mars, more than fourty years ago, thirty-six missions have been launched, including fifty-nine different space systems such as fly-by spacecraft, orbiters, cruise modules, landing or penetrating systems. Taking into account failures at launch, about three missions out of four have been successfully sent toward the Red Planet. The fact today is that Mars orbital environment includes orbiters and perhaps debris, and that its atmosphere and its surface include terrestrial compounds and dormant microorganisms. Coming from the UN Outer Space Treaty [United Nations Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (the “Outer Space Treaty”) referenced 610 UNTS 205 - resolution 2222(XXI) of December 1966] and according to the COSPAR planetary protection policy recommendations [Cospar Planetary Protection Policy (20 October 2002), accepted by the Council and Bureau, as moved for adoption by SC F and PPP, prepared by the COSPAR/IAU Workshop on Planetary Protection, 4/02 with updates 10/0, 2002], Mars environment has to be preserved so as not to jeopardize the scientific investigations, and the level of terrestrial material brought on and around Mars theoretically has to comply with this policy. It is useful to evaluate what and how many materials, compounds and microorganisms are on Mars, to list what is in orbit and to identify where all these items are. Considering assumptions about materials, spores and gas location and dispersion on Mars, average contamination levels can be estimated. It is clear now that as long as missions are sent to other extraterrestrial bodies, it is not possible to keep them perfectly clean. Mars is one of the most concerned body, and the large number of missions achieved, on-going and planned now raise the question about its possible contamination, not necessarily from a biological point of view, but with respect to all types of contamination. Answering this question, will help to assess the potential effects of such contamination on scientific results and will address concerns relative to any ethical considerations about the contamination of other planets.

The present COSPAR Planetary Protection policy has been established in order to conduct scientific investigations of possible extraterrestrial life forms, precursors and remnants avoiding to jeopardize exobiological experimentations. This policy is implemented by the issuance of Planetary Protection recommendations in order to control, limit or avoid the biological contamination of other worlds. Their goal is also to protect the Earth from the potential hazard posed by extraterrestrial matter carried by a spacecraft returning from another planet. Policy and recommendations are built upon scientific opinions and, if available, using scientific results coming from exobiological investigations. If sample preservation is not ensured, inducing contamination or change in sample material properties, some material characteristics can be affected and may induce false results concerning presence of life or biohazard. It concerns in situ investigations as well as analysis of extra terrestrial samples on Earth. False results could lead to propose unappropriate Planetary Protection requirements. This paper will propose recommendations and requirements for sample preservation in order to ensure the validity of exobiological science and directly to consolidate COSPAR policy, giving the best assurance to requirements for forward and back-contamination.

The ROSETTA mission, lead by ESA, will be launched from Kourou by Ariane V in January 2003 and after a long trip, the spacecraft will reach the comet Wirtanen 46P in 2011. The mission includes a lander, built by an European consortium under german leadership (DLR), on which France has a large participation and is concerned by providing a part of the payload and some lander sub-systems.Among these, CNES delivers a specific battery assembly in order to comply with the mission environment and profile, avoiding particularly the use of radioisotopic heaters and radioisotopic electrical generators commonlly used for such missions far from the Sun. The battery includes a pack of lithium-thionyle sulfate cells having a large capacity and a small self discharge rate, able to achieve the nominal lander mission on the comet. A secondary stage, including rechargeable lithium-ion batteries, is used as complement for the main phases of the nominal mission, but is mainly aimed to achieve the extended mission when the comet will come close enough from the Sun in conjunction with the lander solar cells. The battery includes also a specific electronic system dedicated to the battery handling and secondary cells balancing, a mechanical and thermal structure designed, built and qualified in order to comply with low mass constraints.This battery system is presently integrated into the Rosetta Lander flight model and will leave the Earth at the beginning of next year. For the future, such a development and experience could be usefull in the frame of other similar cometary missions. (C) 2003 International Astronautical Federation.

A large number of missions are scheduled, particularly on Mars, in order to search for life or traces of past life. Taking into account CNES past experience in planetary protection related to the Mars 96 mission4,5,6, its planned participation in exobiological missions with NASA as well as its works and involvement in Cospar activities, the paper will give the main requirements in order to avoid celestial bodies biological contamination, including Earth, and to protect exobiological science.

Planetary protection requirements are imposed by United Nations Treaties and handled by the Committee of Space Research giving planetary protection recommendations. In the frame of Solar System exploration missions, the goal of planetary protection is to protect celestial bodies from Earth contamination and also to protect Earth environment from an eventual contamination carried by contaminated samples, return probes or systems. In the field of decontamination and cleanliness, planetary protection takes also into account the protection of exobiological science. United States, through NASA, is involved in planetary protection since the first Solar System exploration missions fourty years ago. The US Space Agency manages planetary protection tasks since a long time now and has set up an organization able to take in charge such activities. Europe has now to start on this topic, imposed by Space exploration missions lead particularly by CNES and ESA. The goal of this paper is to make a statement on planetary protection in european space organizations in order to define the necessary tasks and involvement for building a coherent and original planetary protection policy and an organization able to manage, propose, realize and control planetary protection requirements, works and programs.

In the frame of extraterrestrial exploration missions and since the beginning of the Solar System exploration, it is required, according to the article IX of the OUTER SPACE TREATY (London/Washington, January 27, 1967) to preserve planets and Earth from contamination. Consequently, Committee of Space Research (COSPAR) has established some planetary protection recommendations in order to protect other worlds environment from biological contamination by terrestrial microorganisms, to protect exobiological science for searching life on planets and to protect Earth environment From reverse contamination.Consequently, for the upcoming Mars exploration missions and after the planetary protection recommendations updation, a biological decontamination program has been built for Mars 96 landers. This program includes sterilization of equipment and the integration of the Mars landers in sterile condition in order to ensure the biodecontamination specification. (C) 2002 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.