A future manned trip to Mars would subject astronauts to any number of unpredictable hazards—an unprecedentedly complex launch and journey, bombardment by cosmic radiation, and, if sci-fi movies are to be believed, harassment from potentially unfriendly locals. But there's one effect researchers hope to pin down before anybody gets near a launch pad: the physical and psychological effects of the confinement and isolation that such a long trip would engender.

A study beginning in March will subject six volunteers—four from Russia and two from other European nations—to 105 days of isolation at a Moscow facility as part of the Mars500 program. The subjects will eat, sleep and work in close quarters for the 15-week duration. Today the European Space Agency (ESA) presented its four potential participants, who were winnowed from a field of 5,600 applicants, according to an ESA press release. Two of them will be selected to enter the study and the two others to serve as alternates (to step up if either or both of the chosen drop out) after they all wrap up a two-month training course.

The ESA's four picks are Oliver Knickel, 28, of Germany, and Frenchmen Cedric Mabilotte, 34, Cyrille Fournier, 40, and Arc'hanmael Gaillard, 32. The men come from diverse backgrounds, as depicted in their ESA bios: Knickel is an engineer in the German Army, Mabilotte is a PhD student in international relations and diplomacy, Fournier is an Air France pilot, and Gaillard is an electrical engineer who works on flat-panel displays. According to earlier ESA press materials, the men will receive some compensation for their participation, but not a "big salary."

Another Mars500 study, slated to begin later next year, will subject another six-member crew to 520 days of isolation to simulate a full Mars mission.

Photo of (left to right) Mabilotte, Knickel, Fournier and Gaillard courtesy of ESA/N. Imbert-Vier; photo of Mars500 isolation-study bedroom courtesy of ESA