While Mars One talks about selecting the first humans to colonize the Red Planet, scientists are focused on micro-organisms from Earth that could invade the fourth planet from the Sun. Three recent studies looked at the risks of interplanetary exchange of organisms utilizing research from the International Space Station.
The interplanetary exchange of organisms would make it hard for scientists to find out whether a life form existed on another planet or was introduced there by astronauts. Therefore, it’s necessary to determine what kinds of micro-organisms from Earth can endure a trip to the Red Planet on a spacecraft or landing vehicle.
Currently, Mars-bound spacecraft must meet requirements for a maximum allowable level of microbial life.
“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,” says co-author Kasthuri J. Venkateswaran, a researcher with the Biotechnology and Planetary Protection Group at NASA’s JPL.
However, recent research had demonstrated some microbes are hardier than previously believed, and others may utilize different protective mechanisms to endure interplanetary flights.
Spore-forming bacteria, for example, can withstand certain sterilization procedures. Spores of Bacillus pumilus SAFR-032 have demonstrated extremely high resistance to methods utilized to sterilize spacecraft, like ultraviolet radiation and peroxide treatment. In fact, Bacillus pumilus SAFR-032 was able to endure a simulated Mars environment for 30 minutes.
More recently, Bacillus pumilus SAFR-032 spores were exposed for 18 months on the European Technology Exposure Facility (EuTEF), a test facility positioned outside the ISS.
“After testing exposure to the simulated Mars environment, we wanted to see what would happen in real space, and EuTEF gave us the chance,” notes Venkateswaran. “To our surprise, some of the spores survived for 18 months.”
Interestingly, these spores demonstrated elevated UV resistance when revived and re-exposed on Earth.
In another study, spores of Bacillus pumilus SAFR-032 and another spore-forming bacteria, Bacillus subtilis 168, were dried on pieces of spacecraft-quality aluminum and exposed for 1.5 years to the vacuum of space, cosmic and extraterrestrial solar radiation and temperature fluctuations on EuTEF. They were also exposed to a simulated Red Planet atmosphere utilizing EuTEF. Researchers found that if the organisms were protected against solar radiation, they may be able to survive a journey though space.
The results of a third study implied that space-traveling rocks could carry life between planets.
Researchers placed rock-colonizing cellular organisms in the EuTEF facility for 1.5 years. They selected organisms especially adapted to deal with the environmental extremes of their natural habitats on Earth, and discovered the some are also able to endure the more hostile environment of outer space.
Researchers hope to use their findings to discovery new techniques to lower the risk of contaminating another planet.
All three papers are described in greater detail in the Astrobiology Journal.