A Theoretical Microbial Contamination Model for a Human Mars Mission

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dc.contributor.advisorSebens, Kenneth P.en_US
dc.contributor.authorLupisella, Mark Lewisen_US
dc.contributor.departmentBiologyen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2006-06-14T05:33:28Z
dc.date.available2006-06-14T05:33:28Z
dc.date.issued2006-01-31en_US
dc.description.abstractContamination from a human presence on Mars could significantly compromise the search for extraterrestrial life. In particular, the difficulties in controlling microbial contamination, the potential for terrestrial microbes to grow, evolve, compete, and modify the Martian environment, and the likely microbial nature of putative Martian life, make microbial contamination worthy of focus as we begin to plan for a human mission to Mars. This dissertation describes a relatively simple theoretical model that can be used to explore how microbial contamination from a human Mars mission might survive and grow in the Martian soil environment surrounding a habitat. A user interface has been developed to allow a general practitioner to choose values and functions for almost all parameters ranging from the number of astronauts to the half-saturation constants for microbial growth. Systematic deviations from a baseline set of parameter values are explored as potential plausible scenarios for the first human Mars missions. The total viable population and population density are the primary state variables of interest, but other variables such as the total number of births and total dead and viable microbes are also tracked. The general approach was to find the most plausible parameter value combinations that produced a population density of 1 microbe/cm3 or greater, a threshold that was used to categorize the more noteworthy populations for subsequent analysis. Preliminary assessments indicate that terrestrial microbial contamination resulting from leakage from a limited human mission (perhaps lasting up to 5 months) will not likely become a problematic population in the near-term as long as reasonable contamination control measures are implemented (for example, a habitat leak rate no greater than 1 % per hour). However, there appear to be plausible, albeit unlikely, scenarios that could cause problematic populations, depending in part on (a) the initial survival fraction and death rate of microbes that are leaked into the Martian environment, which depends largely on the possibility for protection from the high UV radiation environment on Mars, (b) organic nutrient availability, and (c) liquid water availability, which is likely to be the limiting survival and growth factor.en_US
dc.format.extent1952535 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/3366
dc.language.isoen_US
dc.subject.pqcontrolledBiology, Microbiologyen_US
dc.subject.pqcontrolledBiology, Ecologyen_US
dc.subject.pqcontrolledBiology, Generalen_US
dc.subject.pquncontrolledmicrobial modelingen_US
dc.subject.pquncontrolledcontamination modelen_US
dc.subject.pquncontrolledmicrobial contaminationen_US
dc.subject.pquncontrolledMars contaminationen_US
dc.subject.pquncontrolledhuman Mars missionen_US
dc.titleA Theoretical Microbial Contamination Model for a Human Mars Missionen_US
dc.typeDissertationen_US

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