Planetary protection

Planetary Protection guidelines were set into place to avert forward and backward contamination of our solar bodies and of Earth due to robotic missions. To comply with these requirements the bioburden of spacecraft is routinely monitored at various stages of its assembly process. Since future missions are set to look for life on other planetary bodies, planetary protection requirements will be revised and most likely new standards, based on viable microbial cells rather then spores, will be set.

The first step in the implementation of planetary protection guidelines encompasses a qualitative and quantitative inventory of the bioburden of spacecraft assembly facilities representing an ‘extreme’ environment for most of the organisms. Within the ESA project MiDiv the microbial bioburden of three different spacecraft assembly halls in different countries (The Netherlands, ESTEC, and French Guyan, CSG) have been investigated in periods where the facilities are in full operation with the assembly and tests of European satellites (SMART-1 and ROSETTA). The analysis of the samples included cultivation on different media at different pH and temperatures with and without oxygen with and without pasteurization, the establishment of a culture collection of bacteria and the partial 16S rRNA gene sequence analysis leading to a phylogenetic classification. The results of these first European measurements give an estimate of the physiological potential of the identified microorganisms and their capability to withstand the different cleaning and sterilizing procedures used up to now for planetary protection measures.

Molecular techniques for the additional identification of non-cultivable microorganisms which represent more than 95 % of all microorganisms on Earth are under development. These new techniques will be utilized in the ongoing planetary protection projects in close cooperation with the NASA counterparts.

For the ESA Pasteur Payload and Rover Phase A Study for ExoMars (by MDRobotics) the planetary protection requirements were reviewed. The already existing, tested and applied cleaning and sterilizing techniques have been assessed together with the experiment-specific requirements. A planetary protection and contamination control plan was implemented into the overall conceptual system design for the Rover/Pasteur payload of ExoMars.

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