Cavenauts, from left: Norishige Kanai from Japan, ESA astronauts Tim Peake and Thomas Pesquet, Randolph Bresnik from Nasa, and Sergey Ryzhikov from Russia. ESA’s cave training prepares astronauts to work as an international team in real exploration conditions. The Sardinian caves are isolated from the outside world. The astronauts need to get used to confined spaces, minimal privacy, technical challenges and limited equipment and supplies for hygiene and comfort – just like in space

Photograph: Vittorio Crobu/ESA