NASA is facing an absolutely massive to-do list as it prepares to send humans to Mars, and the agency is nowhere near tackling everything on it. Simply taking a trip to Mars will be difficult enough, but this is no Apollo-esque brief visit, this will be an effort to set up a permanent colony on the Red Planet, and the challenge is daunting to say the least. Especially from a psychological standpoint.

Right now, the University of Hawaii has been sending volunteers to a remote hillside near the Mauna Loa volcano that sort of mimics the terrain you might expect to see on Mars. NASA sends teams to a biodome in that area to simulate what life would be like on an actual Mars mission, and visitors are not allowed anywhere near it.

Specifically, scientists want to know if volunteers can handle being isolated and live together inside the 11 meter dome for a period of eight months. They take care of every detail, even delaying communications with home in a way that would be similar to the time it would take for communications from Mars to travel to Earth.

Because the challenge is not merely technological, it is how we as humans would handle the tremendous challenges that such a long, isolated trip would create. That is the biggest wild card of all in this effort.

“A team of six volunteer scientists completed one of the most extensive studies of the demands of life on a distant world by closing themselves off to the rest of the world for eight months in an effort known as HI-SEAS,” reads a 2015 NASA statement on what volunteers go through. “Their chore wasn’t so much to stay alive, but to see how isolation and the lack of privacy in a small group affects social aspects of would-be explorers.

“The research is expected to bear directly on NASA’s decisions when composing crews for future missions to Mars. The group also experimented with many budding technologies future Mars explorers could employ during real expeditions to the Red Planet. It was the third and longest of the simulation missions. The next simulation is planned to last a year. A mission to Mars may take two and a half to three years, with approximately half of that time on the planetary surface.”