An Evaluation of Novel Cleaning Techniques for Planetary Protection Applications

NASA has an aggressive plan for exploring Mars. Future in situ life detection and sample return missions will rely on clean and effectively sterile spacecraft to ensure reliable, valid science measurements. These spacecraft levy substantial requirements for planetary protection. Here, we report the results of a comparative analysis of the efficacy of three different cleaning approaches to remove bacterial spores from a series of surrogate spacecraft materials, parts, as well as cleaning challenging structures. The purpose of this study is to identify cleaning methods that achieve a minimum of a 4-log reduction of bioburden from inoculated surfaces. We believe that surfaces efficiently cleaned do not transfer biological particles, particularly spores, which when placed in close proximity with other materials become "effectively sterile." Our results indicate that a novel cleaning method, which utilize vacuum cycle nucleation (VCN) enabled technologies, can effectively remove bacterial spores from surrogate spacecraft material coupons, piece parts and structures. This cleaning technology may be a potential candidate for sterilizing Mars Lander systems, reducing the cost, risk, and material constraints encumbered by use of dry heat sterilization and common cleaning practices.