Planetary Protection Approaches for a Mars Atmospheric Sample Return

The Sample Collection for Investigation of Mars (SCIM) mission proposes to fly through the upper atmosphere of Mars at hypervelocity to collect airborne dust and gas, and return the material to Earth for detailed analysis in a variety of specialized and sophisticated laboratories. SCIM would accomplish the first low-cost return of martian material, and could provide crucial insights into the poorly understood history of water and weathering processes on Mars. Planetary protection forward contamination can be satisfied by straight-forward, established procedures. The more challenging concern for back-contamination of Earth has been directly addressed through a number of detailed engineering analyses to identify which portions of the spacecraft are susceptible to contamination by surviving organisms, combined with in-space heating to sterilize the aerogel collecting medium after acquisition of samples. Systems for "breaking-the-chain" of back contamination have been designed. Review of established heat sterilization procedures on Earth have provided a rationale for specifying a conservative temperature-time cycle for sterilization onboard the spacecraft. In-flight monitoring of onborad systems will provide the Planetary Protection Office with confirmatory information needed to enable approval for final re-targeting of the trajectory to return to Earth.