Microbes may not make it to Mars

The inability of certain microbe species to survive long journeys in space may cause health problems for astronauts travelling to Mars, new research has found.

A paper published in the journal Microbiome details the findings of an ambitious experiment conducted in Moscow to ascertain how bacteria fare inside the closed, cramped conditions of long-distance space travel.

To enable the research, scientists from Germany, UK and Austria constructed a mock-up of the type of space capsule likely to ferry astronauts to Mars, and then locked six volunteers inside it for 520 days, the estimated length of a one-way trip from Earth to the Red Planet.

While confined, the “Marsonauts” took 360 microbial swabs at 20 locations within the faux-craft, and measured the size of, and changes to, the microbiota.

Analysing the results, the researchers, led by Petra Schwendner from the University of Edinburgh in Scotland, found that, not unexpectedly, the humans themselves were the primary sources of the bacteria found. 

The most common microbes found belonged to the bacillus and staphylococcus genera – groups comprising a great many species, some of which can be disease-causing.

Staph species were found in every area of the ship. These microbes often lodge in the human respiratory tract, up the nose and on skin. Schwendner and her colleagues suggest their wide dispersal was probably caused by the movement of shed skin flakes – a theory which squares with the fact that they, and most other bacterial species, were found in greatest density in communal areas, sleeping pods, the gym and the toilet. 

The medical bay was the area with the lowest density of microbial populations. This was, of course, also the area most frequently cleaned.

“We also saw the impact of cleaning agents,” says Schwendner. 

“Although we located some microbial hotspots, where the number of bacteria was much higher than in other areas, we were quite relieved to find that the overall bacterial counts were within the acceptable limits. Due to appropriate cleaning measures, the microbial community inside the habitat was under control at all times with no or little risk for the crew.”

Risk, however, might conceivably arise not from too many microbes, but from too few.

The study found that the number of microbe species present in the spacecraft declined “significantly” during the long mission, prompting concern. High bacterial diversity generally correlates to robust human health, and a loss of species might result in poorer outcomes during months in space.

It is unclear whether the disappearing species were simply unable to maintain sufficient numbers to thrive, or whether, perhaps, they were out-competed by others better adapted to the confined and isolated environment.

“In addition to potential health risks for the crew, some of these microorganisms could have a negative impact on spacecraft, as they grow on and might damage spacecraft material,” observes Schwendner.

“To ensure the system’s stability, countermeasures may be required to avoid development of highly resistant, adapted microorganisms, and a complete loss of microbial diversity.”