A Lunar Microbial Survival Model for Predicting the Forward Contamination of the Moon
Language English Country United States Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.
PubMed
30810338
DOI
10.1089/ast.2018.1952
Knihovny.cz E-resources
- Keywords
- Astrobiology, Lunar spacecraft, Lunar surface, Moon, Planetary protection,
- MeSH
- Bacillus subtilis physiology radiation effects MeSH
- Models, Biological * MeSH
- Spacecraft MeSH
- Cosmic Radiation adverse effects MeSH
- Moon * MeSH
- Microbial Viability radiation effects MeSH
- Extraterrestrial Environment MeSH
- Space Simulation methods MeSH
- Spores, Bacterial physiology radiation effects MeSH
- Ultraviolet Rays adverse effects MeSH
- Vacuum MeSH
- Hot Temperature MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
The surface conditions on the Moon are extremely harsh with high doses of ultraviolet (UV) irradiation (26.8 W · m-2 UVC/UVB), wide temperature extremes (-171°C to 140°C), low pressure (10-10 Pa), and high levels of ionizing radiation. External spacecraft surfaces on the Moon are generally >100°C during daylight hours and can reach as high as 140°C at local noon. A Lunar Microbial Survival (LMS) model was developed that estimated (1) the total viable bioburden of all spacecraft landed on the Moon as ∼4.57 × 1010 microbial cells/spores at contact, (2) the inactivation kinetics of Bacillus subtilis spores to vacuum as approaching -2 logs per 2107 days, (3) the inactivation of spores on external surfaces due to concomitant low-pressure and high-temperature conditions as -6 logs per 8 h for local noon conditions, and (4) the ionizing radiation by solar wind particles as approaching -3 logs per lunation on external surfaces only. When the biocidal factors of solar UV, vacuum, high-temperature, and ionizing radiation were combined into an integrated LMS model, a -231 log reduction in viable bioburden was predicted for external spacecraft surfaces per lunation at the equator. Results indicate that external surfaces of landed or crashed spacecraft are unlikely to harbor viable spores after only one lunation, that shallow internal surfaces will be sterilized due to the interactive effects of vacuum and thermal cycling from solar irradiation, and that deep internal surfaces would be affected only by vacuum with a degradation rate of -0.02 logs per lunation.
Centre for Research in Earth and Space Science York University Toronto ON Canada
Department of Plant Pathology University of Florida Gainesville Florida
Department of Radiation Dosimetry Nuclear Physics Institute of the CAS Praha Czech Republic
Radiation Biology Division Institute of Aerospace Medicine German Aerospace Center Cologne Germany
Space Biosciences Division NASA Ames Research Center Moffett Field California
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