— Ch. 1 · Defining Contamination Types —
Interplanetary contamination.
~5 min read · Ch. 1 of 7
Forward contamination describes the transfer of life from Earth to another celestial body. Back contamination covers the introduction of extraterrestrial organisms into Earth's biosphere. It also includes infection of humans and human habitats in space by extraterrestrial organisms if such organisms exist. The main focus remains on microbial life and potentially invasive species. Non-biological forms of contamination have also been considered, including sensitive deposits like lunar polar ice. In the case of back contamination, multicellular life is thought unlikely but has not been ruled out. Forward contamination by multicellular life becomes a consideration only for crewed missions to Mars.
Potential Habitats And Survival
Enceladus shows geysers made primarily of salt-rich particles with an ocean-like composition. Heat scans indicate temperatures reaching negative 93 degrees Celsius around fissures where these geysers originate. Europa possesses indirect evidence for its subsurface ocean through tidal heating models. Observations by the Galileo spacecraft strengthened the case for liquid water deep within Europa. Some bacterial spores from Earth were transported on Mars spacecraft. Spores of Bacillus pumilus SAFR-032 survived exposure to vacuum and cosmic radiation when sheltered against solar UV rays. About 50 percent or more of those subjected to other space conditions survived. Certain lichens from arctic permafrost can photosynthesize without liquid water using atmospheric humidity. They are highly tolerant of UV radiation using melanin and specialized chemicals. Research published in July 2017 showed perchlorates become even more lethal to bacteria under simulated Martian UV flux. The surface of Mars is now considered more uninhabitable than previously thought due to toxic reactive oxygen species formed by abraded silicates.