Earth's Microorganisms Could Potentially Contaminate Mars

Scientists are worried about Mars invaders of a different kind. These newly feared foes come in the form of microorganisms from Earth, and new research shows that they could potentially contaminate the Red Planet should we ever successfully make the trek there.

Organisms that hitch a ride on a spacecraft may contaminate other celestial bodies, which would make it difficult for scientists to determine whether life forms already existed on a planet or if they themselves brought it there via spacecraft. However, current practices for limiting such microbial life may not be enough.

"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 NASA Jet Propulsion Laboratory researcher behind the study, explained in a news release.

In fact, spore-forming bacteria have grown particularly resilient and can potentially survive an out-of-this-world journey, especially since they can withstand certain sterilization procedures. Bacillus pumilus SAFR-032 spores, in one experiment, were exposed to harsh environments mimicking those on Mars, on the European Technology Exposure Facility (EuTEF) 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."

Another experiment tested rock-colonizing organisms over the course of 1.5 years in the simulator and found that they could survive the even crueler conditions of outer space, and travel between planets (known as lithopanspermia).

The findings demonstrate how robust some of these microorganisms can be, and how important sterilization procedures. Scientists can focus on developing ways to minimize the risk of contaminating other planets, which could hinder their research for life outside Earth.

This research was based on three scientific papers, all published in the Astrobiology Journal. They are entitled, "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."