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A theoretical microbial contamination model for a human Mars mission.

机译：人类火星任务的理论微生物污染模型。

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Contamination 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.
机译：人类在火星上的存在所造成的污染可能会严重影响寻找外星生命的机会。特别是，控制微生物污染的困难，陆地微生物生长，进化，竞争和改变火星环境的潜力，以及假定的火星生命可能具有的微生物性质，使得微生物污染值得我们关注，因为我们开始计划人类对火星的任务；本文描述了一个相对简单的理论模型，可用于探索人类火星任务产生的微生物污染如何在栖息地周围的火星土壤环境中生存和生长。已经开发了一个用户界面，使全科医生可以为几乎所有参数选择值和功能，范围从宇航员的数量到微生物生长的半饱和常数。与参数值的基线集的系统偏差被视为首次人类火星任务的可能合理方案。总生存人口和人口密度是人们关注的主要状态变量，但其他变量（例如出生总数，死亡总数和生存微生物总数）也可以追踪。通用方法是找到最合理的参数值组合，以产生1微生物/ cm3或更大的种群密度，该阈值用于对较值得注意的种群进行分类以进行后续分析。初步评估表明，只要实施了合理的污染控制措施（例如，栖息地），由于人类任务受限（可能持续长达5个月）而导致的陆地微生物污染在短期内就不会成为问题人口。泄漏率不超过每小时1％）。但是，似乎有可能，尽管不太可能，但可能导致人口问题的情况，部分取决于（a）泄漏到火星环境中的微生物的初始存活率和微生物死亡率，这在很大程度上取决于保护的可能性。 （b）有机养分的可利用性和（c）液态水的可利用性，这可能是限制生存和生长的因素。

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