From tomorrow, Saturday 17 September, ESA astronauts Tim Peake and Thomas Pesquet, Randolph Bresnik from NASA, Norishige Kanai from Japan and Sergey Ryzhikov from Russia will live and work in the dark and humid underground environment for five days on their CAVES 'mission' - a unique underground space experience organised by ESA.

The cave environment is isolated from the outside world, it has confinement, minimal privacy, technical challenges and limited hygiene and comfort. It is a completely new situation with interesting psychological issues: use of artificial light in constant darkness alters the perception of time and of colour and absence of natural time cues from daylight may alter the circadian rhythm and sleep patterns.

As on long space missions, the daily routine is organised around timelines, decided twice daily through a phone line to a supporting 'ground' team at the cave's mouth.

Mission tasks include mapping, photography, and geological and microbiological sampling. The training might also provide valuable material for the scientists studying these caves -- many of them unmapped or unexplored. Sampling methods for future planetary missions are also benefitting, along with psychological and medical studies.

After preparing at the site this week, the team will go underground on Saturday for five days. Emerging into the daylight again on 21 September, the trainees will then go through debriefings as though after a space mission.

Loredana Bessone, astronaut trainer at the European Astronaut Centre in Cologne, Germany is explaining with geologist Jo De Waele and astronaut Tim Peake what the CAVES mission is all about.

Video has been shot shot on location and edited by Vittorio Crobu (additional shooting by Sirio Sechi).