NASA Research: Microbes from Earth Could Invade Mars Before Humans
In the race to colonize Mars, microbes may end up the big winners.
So says new research from the International Space Station and which was included in the conclusions of three recent papers that appeared in the journal Astrobiology: "Survival of Rock-Colonizing Organisms After 1.5 Years in Outer Space," "Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes" and "Survival of Bacillus Pumilus Spores for a Prolonged Period of Time in Real Space Conditions."
All three papers were co-authored by Kasthuri J. Venkateswaran, a researcher with the Biotechnology and Planetary Protection Group at the National Aeronautical and Space Administration's Jet Propulsion Laboratory, whose work confirmed there are micro-organisms from Earth strong enough to stow away on a spacecraft and survive the long voyage to Mars or some other interplanetary destination.
Of course, one of the huge problem with the pollination of another world by Earth microbes, explains Venkateswaran, is that it would them be difficult for scientists to determine whether a life form existed on another planet before the arrival of robotic probes as well as human explorers.
According to NASA officials, spacecraft landing on Mars or other planets where life might exist must currently meet requirements for a maximum allowable level of microbial life, or bioburden, which are based on studies of how various life forms survive exposure to the rigors associated with space travel.
"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," said Venkateswaran.
That assumption may not hold up, though, since recent research has shown that some microbes are much more resilient than anticipated.
Spore-forming bacteria are of particular concern to NASA because spores have been shown to withstand various sterilization procedures, on top of the harsh environs of outer space.
Spores of Bacillus pumilus SAFR-032 have shown particularly high resistance to techniques used to clean spacecraft, such as applications of ultraviolet (UV) radiation and peroxide baths. When scientists subjected the tough little spore to a simulated Mars environment --- which kills standard spores in 30 seconds --- it survived for 30 minutes.
Another test left Bacillus pumilus SAFR-032 spores exposed for 18 months on the European Technology Exposure Facility (EuTEF), a test area mounted outside the space station.
"After testing exposure to the simulated Mars environment, we wanted to see what would happen in real space, and EuTEF gave us the chance," said Venkateswaran. "To our surprise, some of the spores survived for 18 months."
A handful of other hearty microbes were tested, providing new understanding about such microbial communities are able to survive in extremely hostile regions on the earth, as well as how they are affected by radiation.
Future exploration missions can use the results of the latest studies to explore new methods for minimizing the risk of contaminating another planet.