Break-the-chain technology for potential Mars sample return

Any concepts that propose to return samples from Mars would have to assure a very low probability of inadvertent release of Mars material into the Earth's biosphere in order to provide protection against the extremely unlikely possibility that biological hazards could be present in the returned material. Backward planetary protection (aka, containment assurance) requires “breaking-the-chain of contact” with Mars: any Mars material that would reach Earth would have to be inside a robustly sealed sample container, with a high probability that the container exterior is completely free of Mars dust. Furthermore, the integrity of the sample container would have to be maintained (with an unprecedented degree of confidence) until it is delivered to a secure receiving facility on Earth. NASA's Mars 2020 mission has identified, as one of its four principal objectives, caching of carefully selected samples on the Mars surface for possible return to Earth by a future mission (or set of missions). While no decision has been made as to if or when the future mission(s) might take place, the NASA Mars Exploration Program has initiated a preliminary investigation of mission options and development of technology that could be needed for implementation of the most likely options. This paper briefly describes the status of the ongoing investigation of mission options for potential Mars sample return (MSR) following the collection of samples by the 2020 rover, and focuses on work in progress to develop corresponding break-the-chain technology that would be required for MSR, including notional methods for container sealing, isolation, and sterilization.