In Russia, six Marsonauts crew members lived in a mock space capsule for the 520 days it would take to travel to Mars and what they discovered was unexpected. The biggest threat to Marsonauts was their microbes, as they found the long-term confinement impacting microorganisms found inside the mock spacecraft.
The research team from Germany, UK and Austria led the project and through 360 microbial samples from 20 locations at 18 time points, they found that the crew members were the main source of microorganisms within the spacecraft and that overall bacterial counts were within the acceptable limits thanks to cleaning agents used. They also noticed that microbial diversity decreased quite a bit over time indicating that long-term isolation like a trip to Mars could increase health risks for the crew as well as increase risks for damaging spacecraft material.