Experiments in space under Mars-like conditions have led to the discovery of the extreme resiliency of some Earth-bound organisms and the potential they may have for finding life on Mars.
The search for life on Mars is getting some help from a seemingly unlikely source — fungi from around the world.
After European scientists sent Antarctic fungi and lichens (composite plants made of fungi and an algae that grow in crust-like formations on rocks) to the International Space Station they discovered the organisms possess a remarkable resiliency for Mars-like conditions, which may prove useful in humanity’s future explorations for life beyond Earth.
"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," said Rosa de la Torre Noetzel, a co-researcher on the project from Spain's National Institute of Aerospace Technology (INTA), in a press release.
“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 centred around the search for life on the red planet," she said.
According to the Spanish Foundation for Science and Technology (FECYT), the McMurdo Dry Valleys, located in the Antarctic Victoria Land, are considered to be the most similar earthly equivalent 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.
Section of rock colonized by cryptoendolithic microorganisms and the Cryomyces fungi in quartz crystals under an electron microscope. Credit: S. Onofri et al. Image has been cropped
Researchers travelled to these remote valleys to collect samples of two species of cryptoendolithic fungi: Cryomyces antarcticus and Cryomyces minteri.
The tiny fungi were placed in small cells on a platform for experiments known as EXPOSE-E, developed by the European Space Agency to withstand extreme environments, and placed outside the Columbus module on the International Space Station.
For 18 months half of the Antarctic fungi were exposed to Mars-like conditions. More specifically, 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, some samples were subjected to ultraviolet radiation as if on Mars (higher than 200 nanometres) and others to lower radiation, including separate control samples.
The EXPOSE-E platform, where Antarctic fungi and lichens are placed. Credit: S. Onofri et al. Image has been cropped
De La Torre explained that the work, published in the journal Astrobiology, formed part of an experiment known as the Lichens and Fungi Experiment (LIFE), "with which we have studied the fate or destiny of various communities of lithic organisms during a long-term voyage into space on the EXPOSE-E platform."
Researchers from the LIFE experiment have also studied two species of lichens (Rhizocarpon geographicum and Xanthoria elegans) which can withstand extreme high-mountain environments. These have been gathered from the Sierra de Gredos (Avila, Spain) and the Alps (Austria), with half of the specimens also being exposed to Martian conditions.
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, even reaching 80 percent more in the case of the species Xanthoria elegans.
The results showed subdued photosynthetic activity or viability in the lichens exposed to the harsh conditions of space (2.5 percent of samples), similar to that presented by the fungal cells (4.11 percent). In this space environment, 35 percent of fungal cells were also seen to have kept their membranes intact, a further sign of the resistance of Antarctic fungi, according to FECYT.
Based on materials provided by SiNC.