A crew of four peoplethe second in the span of a monthexited the simulated Mars habitat on the Biosphere 2 campus Monday morning after a six-day mission.

SAM, the Space Analog for the Moon and Mars, is an “experimental prototype” designed to help study how people might live in a controlled, pressurized environment on a planetary surface away from Earth.

Sahda Haroon, a Purdue University undergrad and one of the four-member crew said one objective of this mission was to monitor carbon dioxide levels inside the sealed habitat.

“One of the things that was different from the original objective, was that, initially I had planned to do a training profile of the entire habitat. Of the carbon dioxide, that resonates throughout the entire habitat,” Haroon said in a news conference after the crew was released.

She continued, “But, we found it more feasible to do it inside one component and then future crews can go ahead and build on that. So, that’s one of the things that changed. But it was all good fun.”

Haroon created a number of objects using a 3-D printer during her time inside SAM, including a chart documenting the CO2 and a scalpeldemonstrating that crews may be able to create instruments and useful tools in case of emergencies.

Spokespeople for the program say the next crew is planning to spend two weeks inside SAM, building up to longer missions in the future.