On April 27, a four-person crew sealed themselves in an air-tight, pressurized habitat on the grounds of the University of Arizona's Biosphere 2, where eight people conducted a similar experiment more than 30 years earlier.

The Space Analog for the Moon and Mars, or SAM, habitat was created to allow people to experience what it might be like to live on the surface of another celestial body.

On May 2, six days after the first crew members entered the habitat, a crowd gathered to watch them emerge. As valves were released to decompress the habitat, it began to hiss, and a hush fell over the crowd. Minutes later, the pressure inside the habitat matched the outdoors, prompting Linda Leigh – one of the original eight people to live in Biosphere 2 for two years – to turn a red lever and swing open the habitat's airlock hatch.

The crew members spilled out with smiles on their faces and applause in their ears, marking the completion of SAM's first successful mission, Inclusion I.

"It's been a whirlwind, but a good one," said Inclusion I mission commander Cassandra Klos. "I'm so proud of everything we've accomplished together. We are a family and very appreciative to be the very first mission."

A habitat like no other

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Kai Staats, director of research for SAM at Biosphere 2, spearheaded the habitat's design and construction with support from Tech Launch Arizona, Research Innovation and Impact's Technology and Research Initiative Fund, the Controlled Environment Agriculture Center, Paragon Space Development Corporation and NASA.

Staats and his team created SAM to serve as an experimental prototype of a fully enclosed system that could be used to inform humans who might one day live and work in space. Preparation for living in space requires testing the feasibility of mechanical and plant-based life support, learning to maintain food crops in a sealed greenhouse, studying the microbiome of a sealed environment, practicing using tools when conducting an extra-vehicular activity in a full pressure suit, further developing a high-fidelity computer model to help design future habitats, and much more.

"SAM is an analog, which is a place to practice before you do the real thing," Staats said. "You can think of a pool as an analog – a place where you practice swimming safely before entering the ocean. In that respect, this building is an analog for how we might live on the moon and Mars. We're practicing our techniques, procedures, technologies and even our interpersonal interactions before we eventually carry ourselves to another planetary body."

The 1,200-square-foot SAM habitat combines the Biosphere 2 prototype Test Module greenhouse built in 1987 with a workshop, kitchen, common area and sleeping quarters. The Test Module greenhouse includes a hydroponic system to grow food with controlled lighting, humidity, heating and cooling. The workshop provides tools and a place to repair or build equipment for research and mission projects.

About a dozen analog space habitats exist globally, Staats said, but no others are sealed and pressurized like SAM.

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The first mission

Anyone can apply to use SAM to conduct their approved research projects. Inclusion I is the habitat's first mission.

"Each team member brought their own science and mission objectives to this facility," Staats said. Staats and his team also asked the crew to study and report on conditions in the habitat, such as carbon dioxide and oxygen levels and flow.

The crew consisted of Klos, a fine art photographer and curator who visually documented the mission; mission medical officer Eiman Jahangir, a cardiologist, scuba diver, space enthusiast and two-time NASA astronaut candidate finalist; mission engineer Bailey Burns, a Blue Origin aerospace systems engineer focused on environmental control and life support systems; and mission communications officer and accessibility officer Sheri Wells-Jensen, a linguist who teaches at Bowling Green State University in Ohio.

Burns focused on monitoring lung pressure, oxygen and carbon dioxide levels in the habitat. Wells-Jensen helped the team consider the accessibility of the habitat. Jahangir ensured that the team stayed healthy and tested stress mitigation strategies.

While sealed inside, the crew members' only means of communication with the outside world was via delayed email, to simulate the physical reality of being far from Earth. From outside, Staats' team also constantly monitored the pressure, carbon dioxide, oxygen, relative humidity and temperature of the habitat.

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"The team had to learn how to manage the airflow to control carbon dioxide levels. Even their exercise, cooking and sleep patterns affected carbon dioxide levels," he said. "But at no point were they close to harmful levels."

The crew got creative with vegetarian rehydrated and freeze-dried ingredients to prepare meals that resembled those that would be available to lunar or Martian astronauts. They also dehydrated and stored their food scraps so future crews could feed them to mycelium – mushroom roots structures – that in turn produce protein-packed mushrooms.

In addition, Wells-Jensen, who is blind, took a simulated space walk through the habitat's prototype moon-Mars yard – a space filled with very fine basalt and rocks to mimic lunar and Martian surfaces.

"What makes this extraordinary is that she is blind and used a cane," Staats said. "This is quite likely the first time a blind person has maneuvered across simulated Martian terrain in a pressurized space suit while breathing air through an umbilical cord drawn from a pressurized habitat."

Since you can't hear anything outside while wearing a pressure suit, Wells-Jensen could only rely on her team to guide her through the yard by radio.

Wells-Jensen added braille to many of the surfaces inside SAM to guide future crew members who might also be blind.

"My objective was to look at the systems and policies in terms of what would make this a welcoming space for any astronaut regardless of their background or how their body is configured," she said after exiting SAM. "One-quarter of the Earth has some significant disability, and we can't leave them behind. We need everybody with us."

Lessons for space and for Earth

Managing resources in SAM offers lessons not only on how to successfully live on the moon and other planets, but also how to live more sustainably on Earth, say those involved in the project.

For example, Inclusion I was allotted 60 gallons of water for four people over six days.

"They had to be careful with consumption, recycle as much as they could, and engage in daily quality of water analysis as they experimented with filtration," Staats said.

By the mission's end, the crew had used only 40 gallons of water.

"Many of us take 40-gallon showers, let alone live with three companions for six days with that much water," Staats said.

How we will someday live on the moon or Mars is how we should be living on Earth today, the mission participants said.

"Living within your means and living sustainability is not suffering," Wells-Jensen said. "It doesn't hurt you to be a good steward of the resources we were given."

Coming full circle

The Test Module greenhouse portion of SAM was originally built as a prototype for Biosphere 2, a large glass-enclosed habitat designed for research and development of self-sustaining space-colonization technology. Two missions, between 1991 and 1994, sealed Biospherians inside to test the design. Leigh lived in the test module for three weeks in 1989, before her two-year stay in Biosphere 2 with seven others. For over 20 years, the Test Module went unused until Staats had the idea to repurpose it, years after the university assumed ownership of Biosphere 2 in 2011.

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In 2014, Staats was a member of a two-week mission at the Mars Desert Research Station in Utah, which has been run by the Mars Society since 2001.

"I learned a lot," he said. "But as an inventor and entrepreneur, it got my wheels turning, and I thought that I could build something even better – not in a competitive fashion but by using my passion to create an analog that was as close as possible to the real thing."

After years of proposals and fundraising, Staats assembled a team that started building SAM in January 2021.

"We were lucky enough to come across this facility, refurbish it and bring it into a new era of function," Staats said. "This brings us full circle."

Turning science fiction into science reality

Staats said he's often asked why we should spend our time planning to go to the moon and Mars when there are still significant issues on Earth.

"The answer is easy," he said. "We are a species that has been exploring since its birth. We're always looking on the horizon and saying, what's beyond?" As he sees it, we're destined to "become a multiplanetary species."

Arizona state Sen. David Gowen introduced a bill to the Arizona legislature that, if approved as written, would allocate $1.5 million dollars to SAM.

"Arizona has been a great portal to the space industry. This is another project that comes from this great state and university," Gowen said after the crew emerged from SAM. "We want to continue to develop it."

A work in progress

Staats' team will take the crew's feedback and continue to improve upon SAM. The day after the crew exited, Staats and his team were installing a new pressure gauge and water filtration system, and making small modifications based on feedback, such as adding a place to hang flight suits and adding chairs in the Test Module. With each mission, they hope to get closer to a facility that could keep people alive elsewhere in the solar system.

This process is meticulous.

"Over the six days, every hour was accounted for," Staats said. "Everything from sampling water to monitoring pressure to oxygen, carbon dioxide and humidity. They also conducted a series of psychology studies around stress management and documented each day with photos and journaling. It's a complicated machine; it's a spaceship without rockets."

As SAM continues to grow, so will mission lengths. Eventually, missions will be months long. Until them, Staats and his team will prepare for the second SAM crew and mission, Inclusion II, which will run May 10-15.