No one knows for sure what living on Mars might be like. The planet is bitterly cold and almost completely dry. The atmosphere is less than one percent as thick as Earth’s. And Mars is a long, long way from home. So scientists and engineers are trying to figure it all out by creating Mars-like conditions here on Earth.

So far, they’ve built habitats in labs, on a volcano in Hawaii, on an island in the Arctic, and even under the sea. Astronauts and others spend weeks or months inside those enclosures. The tests offer ways to check out equipment, procedures, and how “marsnauts” might handle the isolation.

One project began last June, at Johnson Space Center in Houston. Known as Crew Health and Performance Exploration Analog 1, it’s scheduled to last for a full year. Four volunteers are living in a simulated Mars habitat. Daily life includes a delay of up to 22 minutes in contacts with anyone on the outside — the same lag that would be experienced on Mars. The crew is growing crops, maintaining the habitat, and even doing “marswalks” in a special Martian “sandbox.”

Another Mars habitat also opened last year. Space Analog for Moon and Mars is next to Biosphere 2, near Tucson. It includes living quarters, labs, and a Mars-gravity simulator. Up to four researchers can spend weeks or months inside the sealed lab, checking out equipment or doing other work — work that people might someday tackle on Mars.

Script by Damond Benningfield