The underground expedition lasted for nearly a week

Sep 20, 2012 15:17 GMT  ·  By

Six astronauts who spent nearly a week inside a largely-unexplored cave system in Sicily, Italy, returned to the surface today, September 20, marking the conclusion of the Cooperative Adventure for Valuing and Exercising human behavior and performance Skills (CAVES) 2012 expedition.

The purpose of the test was to see how the team managed to endure underground. Exploring caves is very similar to space exploration, in the sense that small groups of people need to live with each other prolonged periods of time, without intimacy, all while under constant danger and pressure.

Working and living underground is a tiring experience, that challenges both the mind and the body, the participants said upon emerging from the cave. The crew was made up of astronauts from the United States, Japan, the Russian Federation, Canada and Denmark.