In a news briefing following the landing, Nasa spokesperson Steve Stich said: "From a human perspective, all of us feel happy about the successful landing, but then there's a piece of us - all of us - that wish it would have been the way we had planned it.

In a nutshell • The International Space Station is an extremely sterile environment with limited microbial diversity compared to Earth, which may contribute to astronaut health problems like skin rashes and immune issues.

The ISS’s microbial environment most closely resembles a hospital isolation room. It could be making astronauts sick.

Astronauts swabbed more than 800 spots on the International Space Station; their samples contained just 6% of the spectrum of microbial life.