Going underground in Slovenia... to prepare for outer space 1326814 SHARE Divaca, Slovenia: In Slovenia’s dramatically beautiful Karst region, six astronauts have been put through their paces for future missions — not in a flashy futuristic space centre but deep underground in the area’s network of cold, dark and muddy caves. This Wednesday they emerged blinking into the light after swapping their space suits for caving gear and spending six full days underground in the Unesco-listed Skocjan cave system. All in all they completed six weeks of training organised by the European Space Agency’s (ESA) CAVES programme. But why were they heading underground?