Engineers work with the Opportunity unit in the clean room of the Kennedy Space Center.In the coming years, mankind is going to launch several regular space missions to search for extraterrestrial life. But if life is found in samples from Mars, the Moon or Europe, then one should not rejoice too violently. Especially if the found biological forms are too similar to the earth ones. The first and most likely explanation for such a find is microbial contamination of scientific instruments and a spacecraft with microbes from the Earth. As it turned out recently, many of them successfully survive even in space.
In this regard, the careful procedures for assembling, testing, launching and operating spacecraft, which minimize biological contamination of the studied media, come to the fore. To reduce the likelihood of pollution,
NASA’s requirements for a planetary defense for Mars include assembling spacecraft in clean rooms, changing the trajectory of flying spacecraft, and partially sterilizing the landing modules and rovers (at individual system levels or completely).
The assembly of all Martian spacecraft is further extended by requirements, including the creation of clean rooms (ISO class 8 or better), the correct procedures for admitting personnel to clean rooms (special overalls as in the photo above) and the usual cleaning procedures for spacecraft, surfaces and floors for assembly productions. Usually ethyl alcohol (ethyl alcohol) and propanol-2 (isopropyl alcohol, isopropanol) are used for worktops and spacecraft materials, as well as Kleenol 30 for clean room floors.
Despite this practice, laboratories for assembling spacecraft still have resistant microbiomes (101-102 colony-forming units (cfu) per cm², 0.2-300 spores per m²) with "molecular genetics, revealing a taxonomically diverse and dynamic microbial community" , including bacteria, archaea and fungi. The authors of the new
scientific work offer the first biochemical evidence explaining the reason why biological pollution persists in clean rooms.
To find out how the microbiome of a spacecraft survives in clean rooms, the research team analyzed several strains of acinobacteria (
Acinetobacter ) originally found on the Mars Odyssey and Phoenix spacecraft.
The authors of the study found that under very nutrient-poor conditions, most of the tested strains grew and
were fed with cleaning agents used in assembling spacecraft
specifically for cleaning the premises . The work showed that cultures are able to grow on ethyl alcohol as the sole carbon source, while showing reasonable tolerance to oxidative stress. This is important because oxidative stress is associated with a dry environment similar to Mars.
The study showed that these strains of acinobacteria are also able to biodegrade isopropyl alcohol and Kleenol 30. These two cleansers, commonly used in “clean rooms”, are also able to serve as energy sources for the microbiome.
“We give the planetary defense community a basic understanding of why these microorganisms survive in clean rooms,”
said Rakesh Mogul, a professor of biochemistry at California State Polytechnic University. “Something always comes to clean rooms, but one of the questions was why the microbes stay there and why a certain set of microorganisms is constantly found in clean rooms.”
Now we know the answer to this question. From the point of view of the planetary defense, this means that it is necessary to take more stringent measures to clean up spacecraft, focused on the search for extraterrestrial life.
The thorough cleaning of spacecraft is very important in the light of the forthcoming mission to Mars, in order to prevent the
interplanetary pollution of the Red Planet by terrestrial biological forms. The consequences of such pollution may be uncontrollable and do not coincide with scientists' plans for terraforming and greening Mars.
The scientific article was
published on April 19, 2018 in the journal
Astrobiology (doi: 10.1089 / ast.2017.1814).