DLR sample carrier containing bacteria and fungi during its nine-hour journey into the stratosphere.
Credit: NASA


Late last year, astrobiologists let loose a “zoo” of microorganisms that traveled by high altitude stratospheric balloon for nine hours – a journey up to 19 miles (30 kilometers) above the Earth.

At this altitude, the shielding effects of Earth’s atmosphere are greatly reduced, and the temperature, radiation and pressure are akin to the conditions found on Mars.

The astrobiologists were from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt), the DLR.

The DLR scientists took part in a NASA program called “Microbes in Atmosphere for Radiation, Survival and Biological Outcomes Experiment” or MARSBOx for short.

Preliminary findings

The results of that September 2019 trip are under analysis by a DLR team. The preliminary biological findings are now available.

The MARSBOx sample holder containing dried mould spores (left) and bacteria (right).
Credit: DLR

“These show that most of the bacteria have been killed, with the strong ultraviolet radiation proving to be particularly problematic for them,” points out a DLR statement on the MARSBOx flight. Only a few staphylococci – human pathogens – survived the journey. In contrast, mould spores survived better under the extreme conditions in the stratosphere.

Some of the organisms underwent testing outside the protective troposphere for the very first time.

Survival properties

Ralf Möller, a microbiologist at the DLR Institute of Aerospace Medicine in Cologne, explains: “In order to proliferate, moulds form spores that are highly resistant to extreme conditions such as dryness and radiation. In addition, fungi have very efficient protective mechanisms against radiation, such as strong black pigmentation and effective DNA repair.”

MARSBOx sample carrier back with the DLR microbiologists.
Credit: DLR (CC-BY 3.0).

Although many bacteria have properties that are similar to this, Möller adds that the mould spores are much more resistant to the extreme Martian conditions than the bacteria that the DLR team tested.

“The results demonstrate how important it is to continue with research into microorganisms,” Möller says, “particularly fungi, and their survival properties in space, not least in the interests of the health of astronauts on long-term missions to space stations and, later, to habitats on the Moon and Mars.”

Earth orbiting research lab – the International Space Station (ISS).
Credit: NASA

Major test campaign

Bacteria and fungi are part of nature and human life. Whether they live on the outside of our bodies – on our skin – or inside us,

Many species of bacteria and fungi are harmless. Some are even useful. On the other hand, there are also varieties that can be dangerous to humans and cause serious diseases. These pose invisible dangers to space travelers on space stations or on future journeys to outposts situated on other worlds, such as Mars.

Issues of “planetary protection” must also be considered. If landers, rovers or other space vehicles carrying bacteria or fungi set down on planets and celestial bodies, they could contaminate the surface.

Investigations into microorganisms under space conditions are ongoing.

For example, as early as summer 2020, samples for a major test campaign will be transported to the International Space Station (ISS) to investigate how they are affected by microgravity conditions in the short and long term.

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