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Recommendation on Orbiting Sample Cleanliness.

  • Cockell, Charles S1
  • Chitale, Rohit2
  • Clement, Brian3
  • Davila, Alfonso4
  • Freeman, Katherine H5
  • French, Katherine L6
  • Glavin, Daniel P7
  • Hays, Lindsay E8
  • Hummel, Kimberly9
  • Meyer, Michael A8
  • Pratt, Lisa M8
  • Salvo, Christopher3
  • Seasly, Elaine8
  • Tsang, Kar Wing10
  • 1 University of Edinburgh, Centre for Astrobiology, School of Physics and Astronomy, Edinburgh, UK.
  • 2 Defense Advanced Research Projects Agency, Washington, DC, USA.
  • 3 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA.
  • 4 NASA Ames Research Center, Moffett Field, California, USA.
  • 5 Pennsylvania State University, Department of Geosciences University Park, Pennsylvania, USA.
  • 6 United States Geological Survey, Denver, Colorado, USA. , (United States)
  • 7 NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, Maryland, USA.
  • 8 NASA Headquarters, Mars Sample Return Program, Washington, DC, USA.
  • 9 Centers for Disease Control and Prevention, Atlanta, Georgia, USA. , (Georgia)
  • 10 US Army Futures Command Combat Capabilities Development Command Chemical Biological Center BioTesting Division, Aberdeen Proving Ground, Maryland, USA.
Published Article
Mary Ann Liebert
Publication Date
Jun 01, 2022
DOI: 10.1089/AST.2021.0058
PMID: 34904891


The National Aeronautics and Space Administration-European Space Agency (NASA-ESA) Mars Sample Return (MSR) campaign involves the collection of samples on Mars by the Perseverance (Mars 2020) rover and their return to Earth. To accomplish this, the Orbiting Sample container (OS) will be sent to Mars to accommodate the collected samples then launched from Mars and returned to Earth, where the samples will be removed for examination in the Sample Return Facility (SRF). Crucial to this entire sequence will be establishment of the required level of cleanliness inside the OS. In February 2021, the NASA Headquarters' Mars Sample Return Program and Office of Planetary Protection assembled an MSR OS Tiger Team (OSTT) to discuss the appropriate cleanliness level options of the interior of the OS. The team's remit was primarily focused on evaluating the trade-offs between Planetary Protection cleanliness levels 4a and 4b. These cleanliness levels are determined by the Committee on Space Research (COSPAR) planetary protection regulations, where 4a requires <300 bacterial spores/m2 and <3 x 105 bacterial spores on the spacecraft (in this case, the interior of the OS) and 4b mandates the more stringent requirement of <30 bacterial spores on the spacecraft. This report documents the consensus opinion submitted by the OSTT that recommended the interior of the OS be cleaned to a 4a requirement with any feasible added effort toward 4b. This report provides, as well, the rationale for that decision.

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