ESA's CAVES training programme began its second phase last Friday as six astronauts ventured into the Sardinian caves in Italy that are their home this week. CAVES mimics elements of spaceflight to prepare astronauts and trainers for the real thing.

Spending time underground might not be the most obvious environment to practise spaceflight procedures but Hans Bolender, Head of the European Astronaut training division explains: "There are many similarities to spaceflight such as a lack of day-night cycle, sensory deprivation, minimal hygiene and the necessity to work as a team and solve problems together."

This year, the CAVES training includes astronauts from all of the International Space Station partners: NASA's Mike Fincke and Drew Feustel from USA, David Saint-Jacques from the Canadian Space Agency, Roscosmos' Nikolai Tikhonov from Russia, JAXA's Soichi from Japan and ESA's Andreas Mogensen from Denmark.

CAVES focuses on human behaviour and aims to help astronauts improve their teamwork and leadership skills. Working in a multicultural environment is also important.

The astronauts spent almost a week getting to know each other and learning the skills required to survive the six days underground.

During their stay in the Sa Grutta caves, they will be presented with tasks and problems designed by the trainers. How they tackle difficulties and work together will help the trainees to assess and improve their capabilities and skills.

During their training week, the astronauts learnt safety protocols, abseiling and roping techniques, mapping and orienteering underground as well as photography lessons in complete darkness for cataloguing any life found during their stay.