After living for 18 months in a Mars-like environment outside the International Space Station, some Antarctic fungi were still living and dividing when examined by researchers back on Earth. This finding comes after examining two species of Antarctic fungi as well as lichens from the Sierra de Gredos (Spain) and the Alps (Austria), as part of the Lichens and Fungi Experiment (LIFE).
The samples were placed in the EXPOSE-E external platform facility on the ISS in 2009 and remained in space for 18 months. Half of the Antarctic fungi were exposed to an atmosphere similar to that of Mars, in a contained environment (mostly carbon dioxide with traces of argon, oxygen, nitrogen and water). Martian radiation was also simulated using optical filters. The other lichen were exposed to different conditions, such as the pure space environment.
The result? More than 60 percent of the Antarctic fungi cells, which generally shelter in rocks in the McMurdo Dry Valley, were still alive when examined by researchers. But only about 10 percent of those cells could still divide after exposure to Mars-like conditions. The Spanish and Alps lichen also showed more viability compared to the ones that had lived in a space-like environment.
Astounding as the finding is, co-researcher Rosa de la Torre Noetzel (of Spain’s National Institute of Aerospace Technology) pointed out that the survival capacity of cells would likely decrease if they remained in Mars-like conditions. This would be, she said in an e-mail to Discovery News, “due to the accumulative dose of extraterrestrial radiation and to the simulated Mars atmosphere composition (high percentage of CO2).”
In terms of planetary protection, de la Torre Noetzel pointed out that previous space experiments provided data on some of the more space-resistant microbes, such as Bacillus subtilis 168 and Bacillus pumilus SAFR-032. While these spores can survive conditions such as vacuum, radiation and temperature fluctuations during a journey to Mars, UV radiation would eventually kill them unless they could hide in cracks or pits on the spacecraft surface.
Landing probes that are shielded from these conditions inside atmospheric entry shields (such as rovers) could host the spores for long periods of time, as the spores would be protected during the journey to Mars. Also, if the lander has shielding against UV radiation, the spores are likely to last for longer. “In this context, cryptoendolithic fungi could survive a longer period to Mars UV irradiation, taking into account the protection of rock material,” she added.
The team has a new experiment on a new generation of exposed facility, called EXPOSE-R2. The experiment is called BIOMEX and began in the summer of 2014. It will compare fungi and lichens with other organisms (such as bacteria, algae and mosses) exposed to space and Mars-like conditions.
“The work will start on the ground, when EXPOSE will be back on Earth (July 2016), trying to identify which of the organisms are particularly resilient, which strategy offers the greatest protection in space, and which biological substances would be suitable as reference markers in the search for life on Mars,” de la Torre Noetzel wrote. “The results will help also to determine whether they might be able to survive on other planets.”
Another recent study found a lack of microbes in certain Mars-like conditions on Earth. Specifically, the researchers detected no microbial activity in certain parts of the McMurdo Dry Valley, specifically in permafrost that remained at temperatures of about -25 degrees Celsius (-13 degrees Fahrenheit). However, there are sandstone boulders and cliffs in the same region where microbes were found.
“The comparison of the different ecological conditions, in the same site both in soils and in the rocks, could provide evidences on the limits to be searched on Mars, which could form the boundaries for the existence of microbes on the planet,” wrote Silvano Onofri, principal investigator for the LIFE experiment, in an e-mail to Discovery News.
“Also for these reason, microorganisms isolated from Antarctic rocks could be models for experiments in space,” added Onofri, who is a professor of systematic botany at the University of Tuscany in Italy.
The new research on the LIFE experiment, led by Onofri, was recently published in Astrobiology.