Image Caption: The European Technology Exposure Facility (EuTEF) attached to the Columbus module of the International Space Station during orbital flight. Credit: DLR, Institute of Aerospace Medicine/Dr. Gerda Horneck

redOrbit Staff & Wire Reports Your Universe Online

In order to avoid potential microbial contamination while searching for signs of microbial life on other planets, the authors of three recently-published studies have used research from the International Space Station to analyze the risks of accidentally transporting organisms from Earth into outer space.

Currently, spacecraft that land on Mars or other potentially habitable worlds have to meet strict requirements for the maximum level of microbial life, also known as bioburden. These permissible levels have been based on studies of how various life forms can survive traveling aboard a spacecraft or landing vehicle.

If you are able to reduce the numbers to acceptable levels, a proxy for cleanliness, the assumption is that the life forms will not survive under harsh space conditions, Kasthuri J. Venkateswaran, a co-author on all three studies and a researcher with the Biotechnology and Planetary Protection Group at NASAs Jet Propulsion Laboratory, said in a statement Friday.

However, recent studies have indicated that such an assumption might not be valid, since some types of microbial live have proven to be hardier than previously believed and others could develop a variety of protective mechanisms in order to handle the rigors of space travel. To that end, each of the three new studies set out to investigate different types of organisms to find out how they might react to an interplanetary voyage.

The researchers are most concerned with spore-forming bacteria, since they are able to survive following some types of sterilization procedures and could be most capable of surviving after leaving Earth. In particular, Bacillus pumilus SAFR-032 spores have demonstrated high resistance to the techniques typically used to clear spacecraft, including ultraviolet radiation and treatment with peroxide, the researchers said.

They exposed Bacillus pumilus SAFR-032 to simulated conditions on Mars an environment capable of killing many other types of bacteria in just 30 seconds and found that it was able to remain alive for 30 minutes. In another experiment, they exposed the spores to 18 months on the European Technology Exposure Facility (EuTEF) external testing ground, and found that some of them were able to survive for the entire duration.

According to NASA, the surviving Bacillus pumilus SAFR-032 spores had higher concentrations of proteins associated with UV radiation resistance and, in fact, showed elevated UV resistance when revived and re-exposed on Earth. The findings also provide insight into how robust microbial communities are able to survive in extremely hostile regions on Earth and how these microbes are affected by radiation.

A second study involved drying out spores of Bacillus pumilus SAFR-032 and another spore-forming microbe, Bacillus subtilis 168, on pieces of spacecraft-quality aluminum. They were then subjected to 18 months of the vacuum of space, as well as cosmic and extraterrestrial solar radiation and temperature changes, on EuTEF. The samples were then subjected to a simulated Martian atmosphere using the external testing facility.

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Scientists Working Hard To Prevent Microbial Invasion On Other Worlds