Some of Earth's microbes can survive on Mars' surface temporarily, suggests study

Some microbes found on Earth may temporarily survive on the surface of Mars, according to a study that could be vital for the success of future missions to the Red Planet.

The researchers from NASA and German Aerospace Center tested the endurance of microorganisms to Martian conditions by launching them into the stratosphere, the second major layer of Earth's atmosphere which closely represents key conditions on Mars.

The study, published in the journal Frontiers in Microbiology, paves the way for understanding not only the threat of microbes to space missions but also the opportunities for resource independence from Earth.

"We successfully tested a new way of exposing bacteria and fungi to Mars-like conditions by using a scientific balloon to fly our experimental equipment up to Earth's stratosphere," said Marta Filipa Cortesao, joint first author of the study from the German Aerospace Center.

"Some microbes, in particular spores from the black mold fungus, were able to survive the trip, even when exposed to very high UV radiation," Cortesa said.

When searching for extra-terrestrial life, scientists need to be sure that anything that they discover has not just travelled from the Earth.

"With crewed long-term missions to Mars, we need to know how human-associated microorganisms would survive on the Red Planet, as some may pose a health risk to astronauts," said joint first author Katharina Siems, also based at the German Aerospace Center.

"In addition, some microbes could be invaluable for space exploration. They could help us produce food and material supplies independently from Earth, which will be crucial when far away from home," Siems said.

Many key characteristics of the environment at the Martian surface cannot be found or easily replicated at the surface of Earth, however, in middle stratosphere, the conditions are remarkably similar.

"We launched the microbes into the stratosphere inside the MARSBOx (Microbes in Atmosphere for Radiation, Survival and Biological Outcomes experiment) payload, which was kept at Martian pressure and filled with artificial Martian atmosphere throughout the mission," explained Cortesao.

"The box carried two sample layers, with the bottom layer shielded from radiation," she said.

This allowed the researchers to separate the effects of radiation from the other tested conditions: desiccation, atmosphere, and temperature fluctuation during the flight.

The top layer samples were exposed to more than a thousand times more ultraviolet (UV) radiation than levels that can cause sunburn on our skin, they said.

"While not all the microbes survived the trip, one previously detected on the International Space Station, the black mold Aspergillus niger, could be revived after it returned home," Siems explained.

"Microorganisms are closely-connected to us; our body, our food, our environment, so it is impossible to rule them out of space travel,” she said.