In order to create a functional base on Mars, NASA and its private competitors will need to design the physical and digital technology needed to transport humans and what keeps them alive between a 33.9 million miles journey and a safe landing. But the mission won’t end there. Astronauts will need to work effectively together to make the whole project both sustainable and worthwhile. Given the extremity of the conditions, that’s no small ask.

Since 2013, HI-SEAS has run four separate behavioral experiments simulating the isolation and stress that a human crew would endure on the way to Mars and on the planet’s surface. The best way to do the latter, according to Project Manager Bryan Caldwell, is to send a bunch of scientists to live in hostile terrain. Mauna Loa, separated from civilization by 20 miles of lava fields and a simulated 22-minute communication delay, does the trick nicely. The first three experiments lasted four, four, and eight months respectively. The crew of HI-SEAS IV, a six-person team of scientists, were expected to treat the outside world as otherworldly and deal with the same deprivations as the first space pioneers for a full calendar year. As though retaining sanity wasn’t a big enough task, the scientists were also given various tasks and research to do while in the dome. While some of their duties simulated the day-to-day activities of real Mars astronauts, the crew’s primary function was to serve as test subjects in 13 different behavioral experiments. Outside of the dome, a team of multidisciplinary researchers monitored every aspect of the crew’s lives, hoping that they could pinpoint the “right stuff” for humanity’s next giant leap.