A simulated Mars flight has given scientists valuable insights into the likely risks from bacteria on spacecraft.
An experiment in which astronauts remained in a confined simulator for a year and a half has showed the need to carefully monitor the changes in the numbers and varieties of microorganisms, such as bacteria, during lengthy missions.
Checking how such species adapt to the confined conditions on board spacecraft could help ensure a safe environment for astronauts on long missions to Mars.
Regular sampling of surfaces and analysis of the types of bacteria present could help prevent the spread of resistant or harmful bugs, and encourage a healthy mix of microbes, researchers say.
The results of the study, involving Edinburgh scientists, will inform estimates of risk to such flights and aid the design of missions.
Scientists studied the results of sampling by a crew of six astronauts who lived in a mock-up spacecraft, located in Moscow, for 520 days.
The Mars500 team never left the closed habitat, and collected 360 microbial samples from 20 locations over the course of their isolation, using air filters and swabs.
The number of different bacteria and other species decreased significantly over time.
Researchers say this may indicate potential challenges in maintaining a diverse mix of organisms, which is normally associated with healthy, stable environments.
Despite the presence of bacterial hotspots, such as the gym and toilet, the overall bacterial counts were within acceptable limits and routine cleaning ensured little or no risk to crew.
Their study, funded by the German Aerospace Centre, Europlanet 2020 and the European Space Agency, was published in the open access journal Microbiome.
Until now, little was known about the influence of long-term confinement on the microorganisms in habitats that may one day be used to travel to other planets. Ours is the first comprehensive long-term study that investigates the number, diversity and changes in microorganisms in a closed habitat for the full duration of a simulated flight to Mars.