Planetary protection technology for Mars Sample Return

The NASA Mars Exploration Program has recently adopted a plan that includes a first Mars Sample Return (MSR) mission proposed for launch in 2013. Such a mission would deal with two new categories of planetary protection requirements: (1) assuring a very low probability of inadvertent sample release in order to provide extra protection against the extremely unlikely possibility of biological hazards in the returned material; and (2) keeping the samples free of round-trip Earth organisms to facilitate evaluation after return to Earth. This paper describes the planetary-protection-related technical challenges awaiting any MSR mission and describes work in progress on technology needed to meet these challenges. New technology is needed for several functions. Containment assurance requires breaking the chain of contact with Mars: the exterior of the sample container must not be contaminated with Mars material either during the loading process or during launch from the Mars surface. Also, the sample container and its seals must survive the worst Earth impact corresponding to the candidate mission profile, the Earth return vehicle must provide accurate delivery to the Earth entry corridor, and the Earth entry vehicle must withstand the thermal and structural rigors of Earth atmosphere entry - all with an unprecedented degree of confidence. Sample contamination must be avoided by sterilizing the entire spacecraft, a challenge with modern avionics, or by sterilizing the sample collection and containment gear and then isolating it from other parts of the spacecraft.