[♪ INTRO]If you asked an astronaut to name the hardest thing about life in space, you might expect them to talk about some of the challenges they’ve faced on spacewalks.

Or maybe the toilet situation. But for a lot of astronauts, one of the hardest parts of being in space is actually the isolation.

On the International Space Station, they’re stuck with just a few people for company,often for six months at a time. And when we eventually send people to Mars,they’ll be spending eight months or so in a rocket. Even when they get there, it’ll just be that small crew living in a little dome.

Sure, they could go outside, but you can’t exactly get a breath of fresh air when the air isn’t breathable. So, space agencies have done all kinds of long-term studies here on Earth to figure out what isolation does to people, and how to make it a little more tolerable. Isolation can be so harmful that these experiments need to be designed very carefully to make sure they’re safe.

Because some of the earliest isolation studies didn’t go very well. Take the story of the cave scientist Michel Siffre, for example. His work wasn’t specifically focused on space travel, but the isolation was similar.

He volunteered to live by himself in subterranean environments to study the effects of isolation from time cues, like day/night cycles, on the human body clock. And the second time he did this, in 1972, was kind of a disaster. He spent six months in a cave in Texas, and by a couple of months in, the humidity had destroyed the books and magazines he brought with him so he had nothing to do.

The experience was so stressful that he fell into a deep depression. Close to the end of the experiment, there was a lightning storm, and he started getting electric shocks through the electrodes attached to his head. He was so out of it that it took four shocks before he realized that he needed to takeoff the electrodes to stop the pain.

Fortunately, Siffre recovered after some time above ground,and went back underground in 1999. But space isolation researchers definitely don’t want anything like that happening to their subjects, so these days there’s a lot more forethought and careful monitoring. They run their experiments on the following basic plan: put a crew together, monitor their sleep, metabolism, and psychological state, and see what they can learn about keeping a crew healthy, productive, and not at each other’s throats.

And while they’re running the long-term isolation studies, there are also other studies investigating how well those isolation studies work. It’s all very meta. For example, NASA’s Human Exploration Research Analog, or HERA, sticks volunteers in a little habitat, or as the cool kids call it, a hab, for a month and half.

The subjects use virtual reality simulators to conduct research on near-Earth objects,and the researchers monitor their sleep, metabolism, and mood. All these data, apart from being used in psychological and wellness studies, are used to fine-tunethe protocols for longer isolation studies. For instance, it turns out that people don’t especially enjoy wearing four different body-monitoringdevices at the same time, and that six check-in sessions per day are super distracting.

Worrying about distractions and comfort might sound nit picky, but the stress that volunteers experience needs to be intentional, and not produced by the data-gathering process. Otherwise, the validity of the experiments can become questionable. So what kinds of stress are intentional in these studies?

Well, at the Hawai’i Space Exploration Analog and Simulation, or HI-SEAS, they’re really concerned about boredom, because extended periods of boredom can make you depressed or anxious — like what happened to Siffre. HI-SEAS sets up crews of six to live in a hab on the slopes of the Mauna Loa volcano,which is remarkably similar to Mars. Like Mars, it’s got lots of volcanic rock and soil, and also like Mars, there’s not much growing on it.

The crew can access the internet and have some family communication time, but it’son a 20-minute delay to simulate the upload and download times between Mars and Earth. And they can’t leave the hab except on planned excursions in spacesuits,so they spend a ton of time together. One of the focuses of HI-SEAS is food boredom, which is when you get tired of eating the same food all the time.

So the crew on the first mission were given non-perishable ingredients and told to get creative, and they sure did. The availability of spices let them really go wild with Spam,and Nutella was a crew favorite. To stave off non-food-related boredom, the crew tried to break things up by celebrating birthdays and research milestones, and some of them took up new hobbies to keep themselves occupied when they had downtime.

But even so, they all did get pretty restless, which isn’t surprising when you’re stuck in a space yurt. Another HI-SEAS mission, which lasted 12 months, was all about feeling connected even whenyou’re secluded on a lava flow, with the help of a virtual reality program called ANSIBLE. It used things like nature scenes, virtual celebrations of family and cultural holidays,and meditations on subjects like gratitude to help the volunteers feel less alone.

These things had been shown to help people de-stress in the real world, but whether or not they’d work in a simulated environment was another matter. According to the initial results, the volunteers did feel more connected to their family and friends, suggesting that VR can be a good tool to help astronauts combat social isolation and maintain important relationships, even all the way from Mars. Over the years, experiments like these have helped space agencies figure out how to make life as an astronaut at least a little more comfortable.

And maybe by the time we’re ready to send people to Mars, we’ll be able to make the trip downright pleasant. Thanks for watching this episode of SciShow Space! To learn more about the strange things astronauts have to deal with, you can check out our video about the unexpected dangers of space travel.[♪ OUTRO]