In an effort to prepare astronauts for the claustrophobic, sensory-deprived, alien-esque setting of living among the stars, space agencies are turning to Earth's own underground cave systems.

Starting July 1, the European Space Agency will send six astronauts into a deep cave system in Sardinia, Italy. For nearly a week, the team will descend more than 2,400 feet underground to experience a dark and eerily beautiful world that simulates the environmental stressors of space. Called CAVES — Cooperative Adventure for Valuing and Exercising — the training will include procedures for moving along a cave wall (analogous to a spacewalk) as well as "multicultural approaches to leadership, following orders, teamwork and decision-making."

This summer's team includes ESA astronaut Pedro Duque, Japanese astronaut Aki Hoshide, Chinese astronaut Ye Guangfu, Russian cosmonaut Sergei Korsakov and NASA astronauts Jessica Meir and Richard Arnold.

"We are very pleased to include the first female astronaut and first 'taikonaut' [Chinese astronaut] in this CAVES course," mission director Loredana Bessone said in a blog post, "creating an even better mix of cultures and experience to put the astronauts' behavior to the test."

In addition to exploring the cave system and charting previously unknown sections, the team will also be testing a new communication device called xFerra. The portable radio transceiver is capable of sending messages through 1 kilometer of solid rock, an unheard of capability when deep underground.

"The Ground team will be much more aware of what we will be doing inside, but they will also test different methods for data entry, storage, data linking and backup," the ESA site states. "We do this with the intention of deriving requirements for the next generation of CAVES operations tools, but also to start preparing operational concepts for future space-exploration missions."

You can follow the team's progress underground through Twitter and/or on the project's official blog site.