Preliminary Results from Microbial Field and Dispersal Experiments in Mars Analog Environments

The potential for planetary contamination by microorganisms from Earth is perhaps the greatest challenge in the search for life beyond Earth. NASA Planetary Protection has developed and employed effective contamination control protocols to minimize forward contamination through mission operations. Recent research indicates that microbial bioburden persists in cleanrooms and other spacecraft facilities. This is especially of concern for crewed missions because maintaining sterility will be nearly impossible. To operate successful life detection missions amidst this potential contamination, we need to be able to understand when contaminants and contaminant classes begin to appear and overprint indigenous life and biosignatures. Through a multidisciplinary approach of environmental microbiology, organic chemistry, and particle flow visualization, we designed pilot field and detection experiments in extreme field environments. To evaluate forward contamination detection methods, various active and passive microbial and particle collection and detection methods including microcosms, aerosol samplers, and witness material were deployed at Valles Caldera, NM, and Carlsbad Caverns, NM. Carlsbad Caverns is a subsurface site characterized by low natural microbial biomass, high human traffic, and a more predictable air flow. In contrast, Valles Caldera is a geothermally influenced surface site with high microbial biomass adapted to extreme acidity, less human traffic, and a less predictable airflow. Collectors were deployed at four different locations per field site across an expected contamination gradient and subsampled at four different times over a one-year period. Preliminary data confirms the utility of all collection methods in capturing microbes, organics, and inorganic particles from the atmosphere and the human aerodynamic wake and initial analysis of DNA sequences reveals that communities differ among collection method and location. We now report these preliminary lessons learned and data from Carlsbad Caverns.