To prevent forward contamination and maintain the scientific integrity of future life detection missions, it is
important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory
spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated habitats, spores of
Bacillus pumilus SAFR-032 exhibited unusually high resistance to decontamination techniques such as UVradiation
and peroxide treatment. Subsequently, Bacillus pumilus SAFR-032 was flown to the International
Space Station (ISS) and exposed to a variety of space conditions using the European Technology Exposure
Platform and Experiment Facility (EuTEF). After 18 months exposure in the EuTEF facility under dark space
conditions, SAFR-032 spores showed 10 to 40% survivability, whereas a survival rate of 85 to 100% was
observed when these spores were kept aboard the ISS under dark simulated-Mars atmospheric conditions. In
contrast, when UV (>110nm) was exerted on SAFR-032 spores for the same time period and conditions using
the EuTEF, a ~7-log reduction in viability was noticed. However, the UV exposure still did not inactivate all the
spores as 19 CFUs were later isolated via cultivation. A parallel experiment was conducted on Earth with
identical samples but under simulated conditions. Spores exposed to ground simulations showed less of a
reduction in viability when compared with the "real space" exposed spores (~3-log reduction in viability for
Mars UV, and ~4-log reduction in viability for Space UV). The data generated is important to assess the
probability and mechanisms of microbial survival, microbial contaminants of risk for forward contamination, in
situ life detection, and to safeguard the integrity of sample return missions.
Conference Committee Involvement (1)
Instruments, Methods, and Missions for Astrobiology XIV
23 August 2011 | San Diego, California, United States
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