Experiment in the stratosphere: what microorganisms can survive in Martian conditions

Scientists at the Institute of Aerospace Medicine of the German Center for Aviation and Astronautics and NASA investigated the resistance of various microorganisms to conditions characteristic of the Martian atmosphere.

Some bacteria and fungi were able to survive in such an extreme environment for a long time.

This is reported in the journal Frontiers in Microbiology. 

Scientists managed to recreate Martian conditions over the ozone layer - in the middle of the Earth's stratosphere at an altitude of about 38 km.

Here, the level of solar radiation is comparable to that observed on the surface of Mars in the equator, the researchers note.

For the experiment, scientists prepared four types of microorganisms: cells of bacteria Staphylococcus (staphylococci), Salinisphaera and Buttiauxella, as well as spores of the fungus Aspergillus niger - Aspergillus black (known as black mold and posing a danger to the health of the lungs of people and animals).

• Sample with dried Aspergillus niger spores before placing in a container

• © German Aerospace Center (DLR)

The microbes were sent flying on a NASA research balloon in a special MARSBOx container that recreates the atmosphere of Mars.

In this case, one part of the samples of the studied material was completely sheltered from solar radiation in the lower compartment of this storage.

The other was in the upper compartment.

It was opened to irradiate microorganisms during a flight in the stratosphere (the "exposure" lasted 5 hours 19 minutes).

"We have successfully tested a new way to expose bacteria and fungi to a Martian-like environment by sending a research probe with our experimental equipment into the Earth's stratosphere," said Martha Philip Cortezan, one of the authors of the work on the German side. 

After the balloon landed, the scientists "revived" the microorganisms in the nutrient medium and compared the results with the data of studies of control samples left on Earth.

• Sample container

• © German Aerospace Center (DLR)

Among bacteria, Salinisphaera showed the best survival rates - microorganisms were only slightly affected by radiation and the Martian atmosphere.

The Buttiauxella bacteria did not pass the test and died completely, while the staphylococcal strains, although noticeably affected, were still able to restore metabolic activity.

At the same time, the most tenacious microorganism was the black Aspergillus fungus.

The germination of the spores of this "mold", which survived the flight, continued only with some slowdown.

Studying microbial survival is helping to better predict the potential impacts of space travel, including health risks, the researchers said.

It will also allow scientists not to make a mistake when studying extraterrestrial life and not to confuse an alien microorganism with those brought from Earth.

“When long-term crewed missions fly to Mars, we will need to know if human-related microorganisms will survive on the Red Planet, as some of them can pose a health hazard to astronauts,” notes the study's lead author, at the German Center for Aviation and Space Katarina Sims.

Recall that this is not the first time that scientists have discovered the ability of microorganisms to survive in conditions close to those of Mars.

So, in the depths of the Chilean Atacama Desert, bacteria feeding on methane were found, and in the highlands of the Andes - unicellular algae living in glaciers at an altitude of 5 thousand meters.Also, researchers from Japan found that large colonies of Deinococcus bacteria can live in open space without any protection decades.

At the same time, researchers note not only possible harm, but also fantastic prospects that viable microorganisms can give to people during space missions.

Scientists have previously created a biohybrid device based on nanomaterials and bacteria for future colonists from Earth, which, like plants, converts sunlight, carbon dioxide and water into organic compounds and oxygen.

“Certain microorganisms could make an invaluable contribution to space exploration.

They could help in the production of food and material resources regardless of the supply from Earth, which will be extremely important away from the home planet, ”summed up Katarina Sims.