(liquid or ice). The mission goals of ExoMars, Mars Sample Return, and the Mars Astrobiology Field Laboratory are also likely to include the search for extant or fossil martian life, and the makeup of instrument payloads on many future Mars missions is likely to focus on life detection. The sophistication and sensitivity of Mars lander instruments are evolving in response both to new technologies and information from previous missions, and instrument measurement sensitivities can be expected to improve with each subsequent mission.
Since publication of the 1992 NRC report on the forward contamination of Mars (NRC, 1992), 12 missions (orbiters and landers) have been sent to Mars, 6 of which have successfully completed their scientific objectives (see Chapter 1, Table 1.1). Knowledge of the planet continues to grow rapidly, and the need to revisit bioburden requirements on an ongoing basis is thus critical.7Chapter 4 describes the current scientific understanding of the Mars environment, particularly research on the potential for transient and long-lived liquid water—a key factor in considering the prospects for forward contamination.
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Clifford, S.M., R. Bianchi, M.C. De Sanctis, M. Duke, S. Kim, R. Mancinelli, D. Ming, Q. Passey, S. Smrekar, and D. Beaty. 2001. Science rationale and priorities for subsurface drilling in ’07. Mars Program Office White Paper. Available at <www.lpi.usra.edu/meetings/geomars2001/drilling.pdf>.
Hecht, M.H., and R.S. Saunders. 2003. CryoScout: A descent through the Mars polar cap. Third International Conference on Mars Polar Science and Exploration. Abstract 8078. Available at <www.lpi.usra.edu/meetings/polar2003/pdf/download/alpha_h-k.pdf>.
MEPAG (Mars Exploration Program Analysis Group). 2004. Scientific Goals, Objectives, Investigations, and Priorities: 2004, unpublished document. Available at <mepag.jpl.nasa.gov/reports/index.html>.
Miller, S.L., J.C. Essmiller, and D.W. Beaty. 2004. Mars deep drill—A mission concept for the next decade. AIAA Space 2004 Conference. Paper AIAA 2004-6048. American Institute of Aeronautics and Astronautics, Reston, Va.
MSPSG (Mars Science Program Synthesis Group). 2004. Mars Exploration Strategy 2009-2020, D.J. McCleese, ed. JPL 400-1131. Jet Propulsion Laboratory, Pasadena, Calif.
NASA (National Aeronautics and Space Administration). 2003. Solar System Exploration: The Solar System Exploration Roadmap for NASA’s Office of Space Science. JPL 400-1077-5/03. Jet Propulsion Laboratory, Pasadena, Calif.
NASA. 2004. The Vision for Space Exploration. NP-2004-01-2334-HQ. NASA, Washington, D.C.
NRC (National Research Council). 1992. Biological Contamination of Mars: Issues and Recommendations. National Academy Press, Washington, D.C.
President’s Commission on Implementation of the United States Space Exploration Strategy. 2004. A Journey to Inspire, Innovate, and Discover, June. Available at <www.whitehouse.gov/space/renewed_spirit.html>.
The bioburden is the level of microbial contamination (total number of microbes or microbial density) in or on an item of interest, in this case, a spacecraft. Additional planetary protection terminology is defined in Box 1.1.