Uploaded on Oct 24, 2011 ESA astronauts Tim Peake and Thomas Pesquet, Randolph Bresnik from NASA, Norishige Kanai from Japan and Sergey Ryzhikov from Russia went down to partly unexplored caves in Sardinia on 17 September 2011fortpletely 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. Video has been shot on location and edited by Vittorio Crobu and Sirio Sechi.