After a year in a tiny Mars simulator dome, Carmel Johnston can handle just about anything

Christiane Heinicke

Every element of the HI-SEAS mission was set up to simulate the conditions of a Mars mission, including the dome seen here behind Carmel Johnston.

For a year, whenever she wanted to go outside, Carmel Johnston would put on her airtight suit and helmet, make her way through the dome's airlock with another crew member and then step out into a volcanic landscape, where she would begin to explore the network of lava tubes.

Only Johnston wasn't on a faraway planet. She was in Hawaii.

It was all part of NASA's Hawaii Space Exploration Analog and Simulation Mission (HI-SEAS). From August 2015 to August 2016, the 28-year-old was commander of a six-person crew that spent the year living inside a 1,200-square-foot dome stuck on the side of a volcano in the middle of the Big Island of Hawaii.

It was all to simulate how things really would be if a crew traveled to Mars. If they went outside the dome, they wore spacesuits. They cooked with dehydrated foods and could only communicate with the outside world via a 20-minute email delay. "We had to do everything as if we were living on Mars," Johnston says.

Cassandra Klos

Carmel Johnston was the commander of the six-person HI-SEAS crew.

Why? To see how the six of them would react, so NASA could adjust and prepare for future space-exploration missions.

"The goal was to study the social and psychological aspects," she said, "all the things that can go wrong and do go wrong if we go to Mars."

There are lots of stories Johnston might tell us about what it was like living in such close quarters with five other people, but those stories are still confidential until the final NASA report. But one thing she will say: It was a challenge for each of them to keep their wits and emotions intact.

The key for Johnston was to spend a lot of time exercising. By just four months in, she had already walked 1.5 million steps -- most of it on a treadmill.

"Exercise, in general, was my way of staying sane," she says. There was a treadmill and a stationary bike, and Johnston would also put laundry detergent in a backpack and run up and down the stairs.

In space, astronauts have to do two hours of exercise each day to maintain muscle mass and bone density. To replicate those conditions, the HI-SEAS crew was given the same recommendations. Exercise combats depression and keeps the crew healthy -- and it also created some alone time in the small space. Maybe that's why three of them, including Johnston, ended up running treadmill marathons -- 26.2 miles all in one session -- in the dome.

"I will try my very hardest to never run on a treadmill again," she jokes.

Courtesy of Carmel Johnston

"Four months in the dome. One third down, two thirds to go!" Carmel Johnston wrote on Twitter along with this photo of the crew.

Johnston had been athletic before she went into the dome. Her dad was a runner, and, in high school, she played soccer, ran track and cross country, and snowboarded in the winter. In college she fell in love with running, and she ran a few marathons in addition to one adventure race every year in biking, running and kayaking.

From Whitefish, Montana, Johnston has a bachelor's degree in soil science and a master's in land resources. She was a soil scientist at the National Resources Conservation Service and loved working at the national parks near where she grew up.

She had applied to other missions similar to HI-SEAS before, so she was on a list that received an email about this HI-SEAS yearlong expedition. When she heard they were looking for people who liked the outdoors, worked well in groups and were trained in a specific kind of gas-flux measurement, she thought, "Hey, that's me."

The goal was to figure out the perfect combination of people and personality traits for a Mars mission. Johnston knew, even if it was hard on her personally, that she could add to that research.

"What is something I can do to contribute to the future of space exploration?" she says. "I'm a human being, they can learn from me."

On the mission, her days were filled with scientific research projects that mimicked what would need to be conducted if she were on Mars, exploration of the "Mars landscape" outside and the routine of life in a dome. When there was free time that wasn't spent exercising, she and her crew watched movies or listened to music stored in a large hard drive. They could also access email through that 20-minute delay, so Johnston wrote blog posts and occasionally posted on Twitter via email. 

She also relied on regular emails from her mom to keep her levelheaded and optimistic when it seemed like it was all too much. The group was close, but still, the confinement was a lot to put on six people. "Some of them will be my best friends forever," she says, and some of them "are civil, polite."

Based on what was learned from Johnston's group, future NASA projects will feature crews picked with an ideal combination of personalities, in anticipation of potentially sending a crew to Mars. And, in the meantime, those lessons can be applied on Earth too.

"Everything we learn on Earth will help us be better on Mars, but also, everything we learn on Mars will help us to live better on Earth," she says.

Since she finished the HI-SEAS mission, Johnston been speaking to school groups and doing education outreach. This summer she'll be back working for the National Park Service in Montana, hoping to be outside as much as possible. She has also been training for her first-ever Ironman race in Coeur d'Alene, Idaho, which she'll race in August, a year to the day after getting out of the dome.

"It kind of gave me guidance and a goal to work towards," she says, of the Ironman. She was already fit and had spent a year on the treadmill and stationary bike during the mission. Attempting an Ironman combined everything she wanted and pushed her further. "My training for the Ironman has been a continuation of what we did in the dome," she says.

Though we don't yet know the results of this yearlong study of a crew on "Mars," Johnston left the dome with the feeling that she can accomplish anything she is determined to do, and next month, that means she'll tackle her most difficult race yet.

"I knew that I just survived a year of the hardest mental challenge of my life, so I was looking for a physical challenge next," she says.

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