"Be careful! If you fall here, it's a one-way trip."

My heart races as I glance into the giant hole in front of me. My breathing speeds up, fogging the plastic faceplate of my shiny white helmet. My feet crunch the fragile red volcanic rock as I cautiously make my way past the pit of no return, as I've dubbed it in my mind.

I'm on the Mauna Loa volcano on the Big Island of Hawaii, but the endless expanse of red and black rock makes me feel like I'm on Mars.

That's the point.

I'm visiting the Hawaii Space Exploration Analog and Simulation habitat, or Mars HI-SEAS for short, that's 8,200 feet above sea level and an hour's drive from the beach. Dozens of would-be astronauts from around the world have lived here, as many as six at a time, in a 13,000-cubic-foot white dome for up to a year of training. They're preparing for potential missions to Mars.

Mostly researchers and scientists, they wear spacesuits every time they venture outside, and they experience 20-minute delays, each way, whenever they communicate with the outside world.

Today, I get to be one of them.

"The Mars base is as far away from civilization as it can be on this island," says Henk Rogers, who warned me about the pit of no return. Rogers, an entrepreneur who holds the rights to the Tetris video game and also owns that big white dome, wants to make it possible for humans to colonize both the moon and Mars.

"Sixty-five million years ago, dinosaurs went away," Rogers says. "Why? They were too stupid to get off the planet. We're still here, as dumb as the dinosaurs."

That doesn't mean we're not trying.

President Barack Obama in 2016 made Mars exploration a key goal for NASA, while President Donald Trump last year said he wants American astronauts to return to the moon. Private companies want to break free of the Earth's gravity, too. A startup called Moon Express hopes to send robots to mine the moon. Amazon's Jeff Bezos founded Blue Origin to "seed an enduring human presence in space." Richard Branson's Virgin Galactic bills itself as the "world's first commercial spaceline." And SpaceX CEO Elon Musk aims to go to Mars. SpaceX expects to launch the first cargo mission there in 2022.

"Mars is the next tangible frontier for human exploration, and it's an achievable goal," NASA says on its website. "There are challenges to pioneering Mars, but we know they are solvable. We are well on our way to getting there, landing there and living there."

Before we can live on Mars, though, we have to find out if humans can handle the psychological stresses of isolation, monotony and years cooped up with the same few people in a hostile environment.

That's where the Mars HI-SEAS base comes in, part of the effort by NASA to send humans to the red planet in the 2030s.

Mission dynamics

A University of Hawaii research program funded by NASA, Mars HI-SEAS has hosted six teams of potential astronauts since early 2013. Missions last from four months to a year.

"I came out with a very strong sense that human space exploration is about the mundane," says Kate Greene, a writer and former physicist who was second in command of the first Mars HI-SEAS mission, which lasted four months. "It's about the day-to-day of how to live with other people and how to live with yourself."

I learned what it means to be lonely." Ross Lockwood

That first group looked at the nutritional and psychosocial benefits of prepackaged "instant" foods compared with meals prepared from shelf-stable ingredients. The twin goals: to learn which foods people found more satisfying and how those foods affected the crews' use of power, water, food and supplies.

The next team investigated group dynamics and performance, and the most recent group explored the ideal mix of personalities to send on a long-term mission.

"If you think about a mission to Mars as being a system of systems, the human part of that system, if that breaks, can be just as disastrous as a rocket blowing up," says Kim Binsted, an information and computer sciences professor at the University of Hawaii and the person in charge of the HI-SEAS base. "It's absolutely essential that they be able to work well together."

Not just work well. They'll have to get along, too. Depending on the relative positions of Earth and Mars, astronauts will need about nine months to reach the red planet, will stay there more than 16 months until our orbits line up again, then will spend another nine months flying home.

Roughing it

The University of Hawaii and NASA designed the habitat and missions to mirror the conditions of a real expedition.

I step through the front entrance of the dome and quickly shut the door behind me. A simulated air lock means I can't go through the dome's inner door until the outer closes tight. I pass through plastic curtains before stepping into the main part of the HI-SEAS habitat.

I immediately spot a treadmill, which crew members use every day. The open, 1,200-square-foot ground floor contains desks lined against the walls, a kitchen with shelf-stable ingredients like tortillas and peanut butter, a foldable table for team meals, and a bathroom with a composting toilet (no water or flushing involved).

Chris Skinner

There's also a lab for conducting experiments and a shower each person can use for eight minutes a week, total. A steel shipping container attached to the dome functions as a workshop where people can work on their projects. A peephole by the kitchen provides the only view they have of the outside world when they're not wearing spacesuits.

Power comes from large solar panels installed near the dome. Batteries store the solar energy for use at night, and hydrogen fuel cells provide backup power in case it's too cloudy to generate all the needed power.

Cramped quarters

The upstairs loft is where the astronauts get any semblance of privacy. I find six tiny rooms arranged like spokes on a wheel, each holding a narrow bed. A few also have a tiny desk or nightstand. I can stand up straight at the entry to each room, but I have to stoop as I walk toward the sloping back wall.

Those six bedrooms together, along with a single half bathroom, take up 424 square feet, slightly larger than the average hotel room in the US. It's definitely tight quarters.

It's about the day-to-day of how to live with other people and how to live with yourself." Kate Greene

For comparison, the Engineering Toolbox reference site recommends allotting 100 to 400 square feet of space per person when designing apartments. The bedrooms in the HI-SEAS habitat provide less than 70 square feet. When you factor in the main floor, each inhabitant has a slightly more comfortable 271 square feet of elbow room.

But while the cramped living space is a challenge, the hardest part to deal with might be communicating with the outside world. Each message sent to friends and loved ones takes 20 minutes to get there, and each response takes 20 minutes to return. Even loading a website takes 40 minutes (20 minutes for the internet server to receive your request and 20 minutes for it to respond). These delays rule out Skype, instant messaging, streaming and phone calls.

"I learned what it means to be lonely," says Ross Lockwood, who worked on his doctoral thesis in condensed matter physics while a member of the second HI-SEAS mission in early 2014.

People can check emails and download movies and music, although that can be frustrating, too.

"If you wanted to watch Netflix, you could navigate to Netflix.com and see a countdown timer that said '40 minutes from now, the content you've requested becomes available,'" Lockwood says. "It was a hassle to use the internet at all."

To get around that, Lockwood programmed the habitat's computer to preload all of the sites he wanted, while he was sleeping, so he could browse them faster when he woke up.

Even with the hardships, Greene and Lockwood both said they wouldn't hesitate if called to go to space.

Closer to home

The last time humans left Earth's orbit was in 1972 when Apollo 17 astronauts Eugene Cernan and Harrison Schmitt roamed the Taurus-Littrow lunar valley and Ronald Evans piloted the command module until their return.

"The science that came out of those [Apollo] missions was tremendous," says Jeffrey Gillis-Davis, a University of Hawaii associate researcher studying moon volcanology. "We learned a lot about Earth's nearest neighbor and applied that to Earth and other objects in the solar system."

Many people think it's about time we returned, President Trump included.

Mars is the next tangible frontier for human exploration." NASA

Last December, he signed a policy directive for the US to "lead the return of humans to the moon for long-term exploration and utilization, followed by human missions to Mars and other destinations."

"It marks a first step in returning American astronauts to the moon for the first time since 1972, for long-term exploration and use," he said during the signing ceremony. "This time, we will not only plant our flag and leave our footprints. We will establish a foundation for an eventual mission to Mars, and perhaps someday, to many worlds beyond."

Rogers has been working to persuade space organizations around the world to train potential moon-bound astronauts on Hawaii's Big Island. He and his team have been looking at a location near the Mars HI-SEAS habitat to create a new base for just that.

The training would be more than just psychological. Because the rough landscape and the moon's surface are so alike, Hawaii is an ideal training ground for driving lunar rovers and creating construction materials from moon rock.

"If we're going to the moon or Mars, we need to be able to use the resources available there for construction: for habitat, for shelter, for water," says Rodrigo Romo, program director of the Pacific International Space Center for Exploration Systems, a Hawaii government agency conducting materials research into using volcanic rock for bricks, tools, glass and fibers that shield against heat or radiation.

Back to Earth

My legs feel wobbly after narrowly dodging the pit of no return. I raise the clear plastic faceguard to take a big gulp of air -- something I'd never be able to do on Mars. My hands fumble in the bulky black gloves, and visions of my smartphone falling into the abyss flash through my mind.

Mark Mann

I follow Rogers, Romo and the rest of our expedition back across the shiny black volcanic rock and rust-color terrain, watching my feet so I don't miss a step. I hear Rogers speaking through the sound system in my helmet as he explains the landscape we're seeing and why the location would be perfect for preparing for trips to outer space.

I'm relieved when I see the Mars HI-SEAS habitat's white dome on the horizon. I know I'll soon be back inside and able to shed my hot suit.

As I pause before entering the dome, I can't help but wonder what life will really be like on Mars 20 years from now.

Will it be a bleak outpost staffed by a few dozen people, the lonely existence Matt Damon portrayed in The Martian -- or a thriving colony?

The one thing I do know for sure: It's going to take a lot of work before we get there.

This story appears in the summer 2018 edition of CNET Magazine. Click here for more magazine stories.

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