What happens to bacteria in space

Microbes in space

There is a great deal of apparently dead rock in our galaxy. But how did life come to earth then? Research has been dealing with this fundamental question for centuries.

One possibility: Organisms reached the planet through space - for example as cargo on asteroids, which then developed here. To do this, however, they would have to be stable enough to survive the tough journey. An experiment on the International Space Station that ended in the spring showed that microbes can do this.

Bacteria, algae, lichens and fungi

As part of the BIOMEX ("BIOlogy and Mars EXperiment") project, which was started in 2014, the German Aerospace Center (DLR), together with other research centers, settled bacteria, algae, lichens and fungi on an external platform of the ISS. There they were exposed to vacuum, intense UV radiation and extreme temperatures for 533 days. Then it went back to earth via Soyuz space capsule.

The result: at least some of the organisms survived in open space. The "winners" included archaea, single-cell microorganisms that have existed in seawater with high salt concentrations for billions of years and that were taken from the permafrost of the Arctic.

Survived and detectable

"They survived under space conditions and can also be detected with our instruments," says Jean-Pierre Paul de Vera from the DLR Institute for Planetary Research in Berlin-Adlershof. Such protozoa are also candidates for life forms that can be imagined on Mars. Science has been looking for such living beings for a long time.

"Some of the organisms and biomolecules have shown enormous resistance to radiation in open space and have actually returned to Earth as 'survivors'", says de Vera. Of course, that doesn't mean that life actually occurs on Mars, he says. "But the search for it is now, more than ever, the most powerful driving force behind the next generation of space missions to Mars."

Not quite five years ago into space

The experiment began on August 18, 2014. At that time, experiment boxes were loaded with several hundred samples and then attached to the outer platform of the Zvezda ISS module by two Russian cosmonauts. Among other things, attempts were made to simulate Mars conditions - with a similar mineral soil composition and a similar atmosphere. Two months later, a protective cover was removed, which meant that the microorganisms were completely exposed to space conditions except for a highly transparent glass. "The ISS once again offered ideal conditions for an experiment that could only be carried out under space conditions," says de Vera.

According to DLR, the results of BIOMEX not only represent progress in the search for life on Mars. They should also serve to establish so-called "biosignatures" for space. To do this, they expand the basis of a database with which other objects in the solar system could also be examined.

(bsc)

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