Members of the CAVES 2013 crew talk about exploring inside the Sa Grutta cave - comparing their experience to arriving on the surface of a planet like Mars, where you don't quite know what to expect.

CAVES, ESA's unique training programme for astronauts, takes place over a couple of weeks in Sardinia's Supramonte. Six astronauts spend two weeks deep in caves, in the dark and cold. They are separated from the outside world, doing scientific research and daily tasks together, as a group, just like in space. Moving in the cave system is also comparable to spacewalking with the use of harnesses and safety devices.

Read more about CAVES on our dedicated website (esa.int/caves) and follow this year's CAVES campaign in the new blog (blogs.esa.int/CAVES2013)