In 1991, four men and four women sealed the hatch on a 3.15-acre ecological ark located an hour north of Tucson, Arizona. They called the structure Biosphere 2 (Biosphere 1 being planet Earth, itself). Their scientific mission: to live inside their artificial ecosystem, removed from the rest of the world, for 24 months.

"I don't think anything could have really prepared us for those two years inside Biosphere 2," says Sally Silverstone, the mission's farm manager and crew co-captain, in this fascinating micro-documentary about the challenges faced by Biosphere 2 and its inhabitants. "Imagine that you were trapped inside, with your immediate family members, for two years, and you didn't get to see anybody else, and you just had to be with them night and day."

"There were some mean times," says Linda Leigh, the project's terrestrial wilderness manager. "People did not talk to each other. It very much was a split of two groups. The main chasm between us was the different ideas of how we would manage the biosphere."

This synopsis, provided by the documentary's creators at The Avant/Guarde Diaries, sets the scene:

Over twenty years ago, a group of scientists, entrepreneurs, philosophers, and free-thinkers put their minds and resources together to create a singular and lasting testament to an unfashionable notion: science and exploration, having become hyper-specialized and incremental, needed a return to big ideas and leaps of faith. They wanted to explore what few were discussing at the time. Things like climate change. Space colonization. And they were going to explore these ideas in a three-acre geodesic living laboratory called Biosphere 2 that mimicked the biomes of the earth. Between 1987 and 1991, they built it from scratch, a veritable ark in the American desert. Eight people sealed themselves inside for two years, harvesting all their food, producing most of their oxygen, and recycling all of their waste. It was a remarkable experiment. And yet the one variable they did not account for was perhaps the most obvious: themselves.

Experiments like Biosphere 2 speak volumes about the psychology of shared space, and the interpersonal dissonance that can arise when quarters are close and tensions are high. Indeed, Biosphere 2 was among the first experiments to examine human behavior under such conditions. Only a handful of studies have attempted anything similar since – and none of them on the scale seen at Biosphere 2.

Studies like these are highly relevant in light of recent talk surrounding deep space exploration and colonization, and private missions to Mars, specifically. Mars One – a reality-television venture that aims to send humans to the Red Planet by 2023 – entails a one-way trip followed by a planetary settlement program. Dennis Tito's Inspiration Mars project, on the other hand, which is hoping to launch in 2018, involves a round-trip mission to the planet lasting 501 days.

These specific projects might never happen, but they both call attention to a pressing consideration. Even if we can figure out how to deliver humans to Mars safely (i.e. without having them bombarded with radiation), our first trip to the Red Planet will require astronauts to spend extended periods of time with one another in very close quarters – possibly for the rest of their lives. Are humans psychologically prepared to handle such conditions? The contentious relationships that emerged over the course of Biosphere 2's two-year mission, and the limited number of studies into close-quarters habitation since then, paint an unclear picture.