Antarctic fungi may hint at potential for life on Mars

An astronaut fixes the EXPOSE-E platform onto the International Space Station. (ESA)

If scientists one day discover life on Mars, they might just want to thank a tiny fungi found on Antarctic rocks.

These cryptoendolithic fungi, which normally are found in the McMurdo Dry Valleys in the Antarctic Victoria Land, were recently sent by European researchers to the International Space Station. After 18 months on board in conditions similar to those on Mars, the researchers found that most survived.

“The most relevant outcome was that more than 60 percent of the cells of the endolithic communities studied remained intact after ‘exposure to Mars,’ or rather, the stability of their cellular DNA was still high,” Rosa de la Torre Noetzel, from Spain’s National Institute of Aerospace Technology (INTA), co-researcher on the project, said in a statement.

“The results help to assess the survival ability and long-term stability of microorganisms and bioindicators on the surface of Mars, information which becomes fundamental and relevant for future experiments centered around the search for life on the Red Planet,” De la Torre added of the work, whose findings were described in a paper published in the journal Astrobiology.

The search for the presence of life on Mars has intensified of late, following the revelations last year that NASA scientists had discovered flowing liquid salty water on Mars.

Section of rock colonised by cryptoendolithic microorganisms and the Cryomyces fungi in quartz crystals under an electron microscope. (S. Onofri et al.)

Scientists have long known that there is frozen water at Mars' poles, but they have never discovered liquid water. The find could have huge consequences for future expeditions, including NASA's goal of sending a manned mission to Mars by the 2030s.ueling the possibility of life on the Red Planet.

The latest work on fungi only adds to the possibly that life could have thrived once on the Red Planet.

Two species of the fungi - Cryomyces antarcticus and Cryomyces minteri – were collected from McMurdo, where earthly conditions are most similar to Mars. They make up one of the driest and most hostile environments on our planet, where strong winds scour away even snow and ice. Only so-called cryptoendolithic microorganisms, capable of surviving in cracks in rocks, and certain lichens can withstand such harsh climatological conditions.

The tiny fungi were placed in cells on a platform for experiments known as EXPOSE-E, developed by the European Space Agency to withstand extreme environments. The platform was sent in the Space Shuttle Atlantis to the ISS and placed outside the Columbus module with the help of an astronaut from the team led by Belgian Frank de Winne.

For 18 months half of the Antarctic fungi were exposed to Mars-like conditions that featured an atmosphere with 95 percent CO2, 1.6 percent argon, 0.15 percent oxygen, 2.7 percent nitrogen and 370 parts per million of H2O; and a pressure of 1,000 pascals. Through optical filters, samples were also subjected to ultraviolet radiation as if on Mars and others to lower radiation.

In contrast, another collection of lichen and fungi samples was subjected to an extreme space environment – and didn’t fare as well. They were exposed to temperature fluctuations of between -21.5 and +59.6 °C as well as galactic-cosmic radiation of up to 190 megagrays and other stressors.

After the year-and-a-half-long voyage, and the beginning of the experiment on Earth, the two species of lichens ‘exposed to Mars’ showed double the metabolic activity of those that had been subjected to space conditions.