For two weeks in October 2025, one man lived inside a sealed environment with 144 pea plants.
ORACLE, Ariz. — How will astronauts breathe, eat and live during long missions to the moon or Mars?
At the University of Arizona’s Biosphere 2, experiments are being conducted inside a structure called the Space Analog for the Moon and Mars, or SAM. It is designed to act like a real space habitat — closed off from the outside world, with air, water and food carefully measured and recycled.
The goal is to practice space missions on Earth before humans head farther into space.
“SAM is the only facility on Earth that can study both machine-based and plant-based processes with humans in the loop in a pressurized facility,” said Kai Staats, SAM’s director of research.
SAM is built around a module first created in 1987 to test whether people could survive in a sealed environment. The structure sat unused for years before Staats led an effort to rebuild and expand it.
Today, the habitat includes sleeping quarters, a kitchen, a bath, an engineering bay, an airlock and systems that track oxygen, carbon dioxide and other life-support needs. It can host long-duration missions with up to four people inside.
One person, 144 plants and two weeks sealed inside
For two weeks in October 2025, Matthias Beach, a member of the SAM development and operations team, lived alone inside the habitat with 144 dwarf pea plants.
The test focused on whether plants could help clean the air. As Beach breathed out carbon dioxide, the plants absorbed it and released breathable air back into the habitat.
“Those peas sequestered approximately 45% of the carbon dioxide generated by [Beach],” Staats said. “On the eighth day, he harvested the pea plants and then delivered those plants out the air lock and watched the [carbon dioxide] rise again.”
The experiment showed that even a small number of crops could play a role in keeping future astronauts alive on the moon or Mars.
“When I harvested the plants, it was actually kind of sad,” Beach said. “I took pictures of a few that I thought were adorable, and I really missed them afterward. I missed hearing the pumps cycle on and off every half hour, the glow of the lights and that smell, the humidity and the green. Without it, the habitat felt more like a spaceship.”
The pea test is just the beginning. Through 2026, researchers plan to test more than 20 crops including wheat, rice, lettuce, spinach and potatoes.
The goal is to build a database showing how much growing space is needed to support human crews and how much air plants can recycle in a sealed habitat.
Plants aren’t the only solution being tested. SAM also includes a new mechanical system that removes carbon dioxide using technology similar to what’s used on the International Space Station, developed under a license with NASA.
Inside SAM, a new medical bay is also under construction.