Mars Returned Sample Handling: Planetary Protection and Science Aspects

The action of returning geological samples from Mars, should it be attempted by robotic missions, will require some careful planning on what would be done with the samples once they are on Earth, and the conditions under which they would need to be kept in order to realize their value. It is generally assumed that returned martian samples would be the subject of two primary kinds of analysis and investigation: planetary protection testing, and scientific analysis to support martian exploration objectives. Testing for the purpose of planetary protection would need to be carried out in a facility that has containment characteristics comparable to those of BSL-4 laboratories. This hypothetical facility has been informally referred to as the "Sample Receiving Facility" (SRF). However, it is not yet known if this capability would be optimized as a completely new facility, as a facility built in partnership with some other existing infrastructure, or if the required functionalities could even be distributed across multiple buildings, perhaps in quite different places. Although the essential purpose of planetary protection testing would be to assess whether or not the samples pose a biological hazard, many of the measurements called for in the draft test protocol, especially those related to preliminary examination/sample classification and life detection, are the same measurements called for to support scientific exploration objectives. Despite the uncertainties in the facility configuration required to carry out PP testing, it is clear that during such tests, the scientific integrity of the samples would need to be maintained. The primary challenge to scientific integrity revolves around contamination control. The science community has a need for the samples to be kept "clean", especially with regards to biological contaminants. However, specific definitions of "clean" have been difficult to establish. Further definition by the Mars science community of their scientific objectives, and the impact of different classes of contaminants (and their quantities) on achieving those objectives, needs to be done. Requirements derived from such an analysis would play a significant role in SRF facility design, the ways scientists are allowed to interact with the samples, the relationship between the instruments and the containment system, and how scientific investigations could be carried out in secondary research laboratories external to the SRF (and if so, of what design).