The question of whether simple life can survive in space is hardly new, but it has lately taken on a new urgency.
It is not only a pressing scientific question — might life from Mars or another body have seeded life on Earth? Might organisms similar to extreme Earth life survive Mars-like conditions? — but it is also has some very practical implications. If humans are going to some day land and live on the moon or on Mars, they will need to grow food to survive.
So the question is pretty basic: can Earth seeds or dormant life survive a long journey to deep space and can they then grow in the protected but still extreme radiation, temperature, and vacuum of deep space?
It was with these questions in mind that the European Space Agency funded a proposal from the German Institute of Planetary Research to send samples of a broad range of simple to more complex life to the International Space Station in 2014, and to expose the samples to extreme conditions outside the station.
Some of the findings have been reported earlier, but last month the full results of the Biomex tests (Biology on Mars Experiment) were unveiled in the journal Astrobiology.
And the answer is that many, though certainly not all, of the the samples of snow and permafrost algae, cyanobacteria, archaea, fungi, biofilms, moss and lichens in the did survive their 533 days of living dangerous in their dormant states. When brought back to Earth and returned to normal conditions, they returned to active life.
“For the majority of the chosen organisms, it was the first and the longest time they ever were exposed to space and Mars-like conditions,” Jean-Pierre Paul de Vera, principal investigator of the effort, wrote to me. And the results were promising.
A microbiologist and planetary researcher at the German Space Agency’s Institute of Planetary Research in Berlin, de Vera and his team went from Antarctica to the parched Atacama desert in Chile, from the high Alps to the steppe highlands of central Spain to find terrestrial life surviving in extreme conditions (extremophiles.)
The samples were then placed in regolith (soil, dust and other rocky materials) simulated to be as close as possible to what is found on Mars. They were rocketed up 240 miles to the space station and ultimately placed outside in space on the EXPOSE-R platform of the Russian ISS module during a Russian astronaut space walk. Several hundred samples of organisms then spent the next 18 months outside, facing the extreme rigors of space.
De Vera called BIOMEX “a novel effort to study systematically representative organisms of the entire tree of life in relation to Mars’ habitability and the limits of life. ” Novel in terms of the kind of life sent into space, and the Mars-like conditions in which they were embedded.
And then to have such a long duration outside the space station gave it additional import.
The results : “Mars seems to be a habitable planet for some tested species,” he said..
“If we are taking all results of all experiments together (pre-flight, during flight and post-flight tests), organisms could resist the environmental conditions on Mars and it is worth to search not just for extinct but also for extant life on Mars. Particularly the search for life in the subsurface is promising. “
He was struck that some of the organisms and biomolecules “showed tremendous resistance to radiation in outer space and actually returned to Earth as ‘survivors’ from space.”
“Among other things, we studied archaea, which are unicellular microorganisms that have existed on Earth for over three-and-a-half billion years, living in salty seawater. Our ‘test subjects’ are relatives of theirs that have been isolated in the Arctic permafrost. They have survived in space conditions and are also detectable with our instruments. Such single-celled organisms could be candidates for life forms that might be found on Mars.”
While the simpler organisms survived, many of the more complex ones — the lichen species and mosses — did not. Too many systems in the organisms failed during the onslaught.
And what did the 18 months in space tell the scientists about panspermia? That’s the long-debated theory that says dormant life may have successfully traveled through space via meteors or other bodies kicked up on Mars and then, long after, landed on Earth?
“The panspermia hypotheses could also be possible,” de Vera said. Especially hardy organisms — with protective pigments, thick membranes and DNA-repair mechanisms –just might be able to survive a journey from Mars to Earth (or from Earth to Mars.)
It would also help greatly if the microbe samples live entirely inside rocks (endoliths.)
This would be necessary if samples were exposed to deep space instead of the low-Earth orbit in which the ISS circles the globe. Being in low-Earth orbit (LEO) means the organisms were protected from some of the most damaging cosmic and solar radiation by the Van Allen radiation belt — a zone of energetic charged particles that are captured by and held around the planet by our magnetic fields. While the Earth’s belts go out as far as 36,000 miles, they are absent in deep space. And so any organism (including humans) would get a much fuller blast of the harmful radiation unless well protected in a capsule.
But if the organisms live within the rocks, “they are very well protected and therefore might also survive such kind of harsh environmental parameters,” de Vera said. “The most resistant organisms within BIOMEX are mainly bacteria and archaea, and they are soil and rock inhabitants.”
The Biomex experiment is not the first to expose microbes to space and the results are not entirely a surprise.
There have been other long-term experiments with seeds on the American EXPOSE platform of the ISS, and in the 1980s bacteria were exposed to space for six years on a Long Duration Exposure Facility satellite. While 30 percent of the bacillus subtilis spores survived that long passage in space, they were embedded in salt crystals –a very different kind of environment than what the Biomex experiment provided. Others in that six year exposure survived in the presence of glucose.
Biomex is different in that the lifeforms were embedded in that simulated Mars regolith, an environment as much like the Martian surface as currently possible, with minerals and molecules known to exists on the planet. (That includes the biologically unfriendly perchlorate salt known to exist on the Martian surface.) Some of the samples were also sealed in compartments with an “atmosphere” as close as possible to that of Mars.
The BIOMEX project is officially a joint mission of ESA and the Russian space agency Roscosmos. But it is also an international and interdisciplinary consortium of 30 institutes in 12 countries on 3 continents,and has NASA participation.
As the BIOMEX samples flew outside the ISS, experiments were also carried out — using identical experimental setups to those in space — in the Mars simulation chamber at the Institute of Planetary Research and in a space simulation chamber at the German Aerospace Center’s Institute of Aerospace Medicine in Cologne. In this way, ‘control samples were created for the experiment and its scientific evaluation.
De Vera hopes that the success of BIOMEX will result in increased research into possible life now on Mars. In principle, he said , the experiment has shown that terrestrial extremophiles are able to exist on Mars, so the door is open to potentially historic discoveries of Martian parallels.
“Of course, this does not mean that life actually exists on Mars,” de Vera is quick to note. “But the search for life is more than ever the strongest driving force for the next generation of missions to Mars.”
And the NASA Mars 2020 rover mission and the European ExoMars rover scheduled to land the same year both have life detection capabilities that haven’t been used on Mars since the inconclusive Viking experiments of the 1970s.
They are rudimentary and some involve complicated and multi-staged sample returns. But the process of searching for signs of ancient life, or of even current life on Mars, has resumed.
Many Worlds 