Technical challenges in meeting the next decade's planetary protection requirements

Abstract

Protecting solar system bodies from biological contamination is of critical importance to the future success of NASA's science and exploration missions, as is protecting the Earth from the importation of life from elsewhere, if it exists. As the planned array of missions grows, the details of the data that drive future planetary protection concerns will be increasingly important. Not all locations on a solar system body will warrant the same contamination control requirements. For example, the picture of Mars that has emerged from the Mars global surveyor and Odyssey missions stands in marked contrast from that portrayed shortly after the Viking missions of the mid-1970s. The water-ice abundance at both the polar caps, and as it is inferred from hydrogen abundance in lower latitudes, is particularly intriguing, adding to a heightened consideration that Mars might support indigenous life - or could be contaminated by life brought from Earth. Elsewhere in the solar system the potential for a liquid-water ocean within Europa, and for liquid water under the surface of other icy bodies - including Saturn's moon Titan - can highlight the problems involved with possible biological contamination that may be carried by future missions. A particular challenge are missions carrying perennial heat sources of high capacity and longevity (e.g., radioactive power sources) which could, by nonnominal landings or other mission operations, be introduced to close contact with water ice -potentially forming Earthlike environments that could accommodate the growth of contaminant organisms. Sample return missions from bodies that may harbor indigenous life will also require carefully contained Earth-return phases, biohazard testing, and initial science studies to be performed in a safe receiving facility. Translating planetary protection requirements into affordable and achievable engineering solutions at both the mission and subsystem level will require that a wide array of tools be accessible to mission designers, as well as an intimate understanding of potential sources of contamination and the accessibility of likely habitats on other worlds. Current priorities for technology development in view of the requirements for the next decade missions are discussed and developed in this paper.