Planetary Protection - Process

Process

The risk of forward-contamination by terrestrial micro-organisms depends on their ability to survive the voyage and on the environmental conditions they find on arrival. The spacecraft must be sterilized before leaving Earth in order to minimize the risk of depositing Earth-originating biological material at the destination. Heat energy, administered in the form of an elevated temperature heat soak over a specific interval of time, is a well-known method for inactivating organisms. Clean room assembly and microbial reduction through heat, chemicals or radiation are the basic techniques used to accomplish microbial control when this is necessary for a mission. NASA currently has only one approved method – dry heat microbial reduction. This technique was used on the Viking Mars landers, which were built and launched in the 1970s. Advanced materials, electronics, and other heat-sensitive equipment being used on spacecraft today could be damaged by such high-temperature treatment, however. Consequently, NASA researchers are developing an alternative sterilization method, a low-temperature, vapor-phase, hydrogen peroxide-based sterilization process. The certification process to support this goal is lengthy and requires substantial fundamental research and method standardization. Two methods being considered for near-term submission to NASA for use on spacecraft are Limulus Amebocyte Lysate assay, and Adenosine Triphosphate assay.