Researchers have explained for through first ever biochemical evidence of how contamination persists in clean rooms and spacecrafts.
Published in journal Astrobiology, the study offers first biochemical evidence explaining the reason the contamination persists. In the clean room facilities, NASA implements a variety of planetary protection measures to minimize biological contamination of spacecraft. These steps are important because contamination by Earth-based microorganisms could compromise life-detection missions by providing false positive results.
Despite extensive cleaning procedures, however, molecular genetic analyses show that the clean rooms harbor a diverse collection of microorganisms, or a spacecraft microbiome, that includes bacteria, archaea and fungi, explained scientists involved with the study. The Acinetobacter, a genus of bacteria, are among the dominant members of the spacecraft microbiome.
To figure out how the spacecraft microbiome survives in the cleanroom facilities, the research team analyzed several Acinetobacter strains that were originally isolated from the Mars Odyssey and Phoenix spacecraft facilities.
They found that under very nutrient-restricted conditions, most of the tested strains grew on and biodegraded the cleaning agents used during spacecraft assembly. The work showed that cultures grew on ethyl alcohol as a sole carbon source while displaying reasonable tolerances towards oxidative stress. This is important since oxidative stress is associated with desiccating and high radiation environments similar to Mars.
The tested strains were also able to biodegrade isopropyl alcohol and Kleenol 30, two other cleaning agents commonly used, with these products potentially serving as energy sources for the microbiome.
For planetary protection, this indicates that more stringent cleaning steps may be needed for missions focused on life detection and highlights the potential need to use differing and rotating cleaning reagents that are compatible with the spacecraft to control the biological burden.