August 1, 2015.
Relative cleanliness in terms of particle abundance in spacecraft assembly facilities is determined by particle counts carried out in clean rooms during resting conditions. Particle counters assess total particles and particle size distribution, but do not distinguish inert particles from biological particles, which may include bacterial spores that are resistant to standard cleanroom sterilization procedures. Current cleanroom certifications do not fully assess the effects of human presence on spacecraft contamination since humans are known symbionts to enumerate microorganisms and assessments are performed at rest when there is no human presence. In this study, contamination risks and bioburden in spacecraft assembly facilities were determined by simultaneous detection of total biological and inert particle content and particle size distribution in JPL cleanrooms during working and resting conditions using BioVigilant IMD-350A, and metadata collection. The findings of this study clearly demonstrate a correlation between human activity levels and elevated levels of biological particles primarily of 0.5 to 1 micron size, contrary to the current literature, as well as elevated total particle counts compared to baseline resting conditions. The results of this study will serve as a model for reassessing current standards for bio-aerosol transport and serve as a feasibility assay to Mars 2020.
Bacteriology | Biotechnology | Environmental Microbiology and Microbial Ecology | Molecular Biology | Other Microbiology
California Polytechnic State University (Cal Poly SLO)
This material is based upon work supported by the National Science Foundation under Grant No. 1340110 and is made possible with contributions from the S.D. Bechtel Jr. Foundation, Howard Hughes Medical Institute, Chevron Corporation, National Marine Sanctuary Foundation, and from the host research center. Any opinions, findings, and conclusions or recommendations expressed in this material are solely those of the authors. The STAR Program is administered by the Cal Poly Center for Excellence in STEM Education on behalf of the California State University system.