As part of the ongoing search for life on Mars, a team of researchers has sent a batch of tiny fungi, growing in the Antarctic region, to the International Space Station (ISS). For the last 18 months, the microorganisms were exposed to conditions similar to those prevailing on the Red Planet. Quite unexpectedly, over 60-percent of their cells have survived, with stable, intact DNA. For the experiment, the group also dispatched lichens, collected from the Austrian Alps and Spain’s Sierra de Gredos, into space.
Situated in the Antarctic Victoria Land, the McMurdo Valleys are commonly believed to be the closest earthly equivalent to Mars, and are home to some of the driest and most hostile climatic conditions found anywhere on our planet. Thanks to its unique location, the region is subjected to incredibly strong winds that scour away even the slightest traces of ice and snow. Only certain types of lichens and cryptoendolithic microbes, basically those that inhabit pores and cracks inside rocks, are capable of withstanding such an extreme environment.
While working in the area a few years back, a group of European researchers collected samples of two different species of cryptoendolithic fungi, namely Cryomyces minteri and Cryomyces antarcticus. As part of the so-called EXPOSE-E experiments, the European Space Agency (ESA) sent the microorganisms into space, on board the Space Shuttle Atlantis. Placed in special cells around 1.4 cm in diameter, the fungi were transported to the International Space Station’s Columbus laboratory.
For the past 18 months, half of the samples were exposed to Mars-like atmospheric conditions, comprising of 95-percent of CO2, around 1.6-percent of argon, 2.7-percent of nitrogen, about 0.15-percent oxygen, approximately 370 parts per million of water vapor and pressure of nearly 1,000 pascals. Using optical filters, the team subjected the Antarctic microbes to intense UV radiation of more than 200 nanometers, as prevalent on Mars. The experiment also included control samples. Speaking about the project, Rosa de la Torre Noetzel, a scientist at Spain’s National Institute of Aerospace Technology and the study’s co-author, said:
… 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. The most relevant outcome was that more than 60% 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.
Recently published in the Astrobiology journal, the study is actually part of the Lichens and Fungi Experiment (LIFE), in which scientists from Italy-based University of Tuscany sent two species of lichens into outer space. Endemic to high-mountain environments, the organisms (belonging to the species Rhizocarpon geographicum and Xanthoria elegans) were originally collected from Austrian Alps and Spain’ Sierra de Gredos.
On the International Space Station, half of the samples were exposed to Martian conditions, while the other half was placed in extreme space environment, with temperatures ranging from -21.5 to around 59.6 ºC, harsh galactic-cosmic radiation of over 190 megagrays and vacuum of somewhere around 10-7 and 10-4 pascals. They were also subjected to intense UV radiation.
At the end of the 18-month-long experiment, the batch of lichens exposed to Mars-like conditions showed twice the metabolic activity as the other group, with the species Xanthoria elegans showing a stupendous 80-percent increase. As observed by the researchers, the lichens subjected to extreme space conditions were found to exhibit reduced photosynthetic activity. de la Torre added:
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.
Source: Agencia SINC