In 1961, Evgenii Shepelev sealed himself inside a small steel cylinder.
Part of a team of researchers at the Moscow Institute for Biomedical Problems, Shepelev and his colleagues were attempting to test an idea first proposed by Konstantin Tsiolkovsky, considered the father of the Russian space program, back in 1911. Tsiolkovsky surmised that deep space exploration would require a closed-loop system in which the air inside a space habitat would need to be recycled. Plants could produce the oxygen for people to breathe while absorbing the carbon dioxide they exhale. It sounds simple enough, but getting the balance just right is a matter of, well, life and death.
And now Shepelev was putting his life on the line to find out if it could work. The interior of the enclosure was only about 160 cubic feet—small enough that he would suffocate quickly unless additional oxygen was supplied. Inside the container with Shepelev was about eight gallons of water containing a type of microscopic green algae. He stayed inside for twenty-four hours—longer than would have been possible if the algae were not producing oxygen. The experiment was a proof-of-concept, demonstrating that the basic theory was sound.
But, luckily, Shepelev left the container just in time. The smell was already putrid by the time he emerged—an indication that something was off. By the next day, the algae population crashed. The Soviet researchers discovered that maintaining a balanced ecosystem inside a sealed container is complicated.
In addition to the technical challenges of creating a functional, closed- loop system capable of supporting human life, there are also challenges that come with knowing you are, in fact, a human trapped inside an airtight container. Indeed, some of the most substantial challenges associated with deep space exploration and settlement are psychological.
The largest and by far the most ambitious attempt to build a closed- loop ecosystem with people inside began on September 26, 1991, when eight people stepped inside a futuristic-looking glass and steel structure in the middle of the desert in Arizona and sealed the door. They called themselves the Biospherians, and they vowed not to come out again for two years. The leaders of the project saw it as a prototype of a space community that might also provide lessons for how to better manage our ecosystems on Earth.2 In addition to large areas for agriculture, the 7.2-million-cubic-foot enclosure contained miniature versions of five biomes—a tropical rainforest, savannah, mangrove wetland, desert, and even an ocean with a coral reef. They called the enclosure Biosphere 2—humanity’s first attempt to recreate the complex ecological relation- ships on the surface of planet Earth, known to biologists as the Biosphere. Each of the five biomes was packed with living things collected from equivalent ecosystems around the world. Trees, shrubs, and grasses were planted along with a menagerie of animals, including insects, fish, frogs, reptiles, birds, and mammals. “We have no way of predicting exactly which and how many of the 3,800 species Biosphere 2 contains will survive,” wrote project cofounder John Allen the year the experiment began. “All that we do know is that the technology will probably keep going and the people, hopefully, will not go crazy.” It was, in hindsight, an optimistic view.
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In May 2024 I walked through the same doorway that the Biospherians had entered at the start of their experiment thirty-three years earlier. By then the massive Biosphere 2 complex had become a research facility operated by the University of Arizona. No longer a sealed enclosure, it was now being used to study how climate change may affect the various ecosystems recreated inside. It also served as a conference venue, which is what had brought me there—to attend the annual Analog Astronaut Conference.
Analogs are a way of simulating a particular aspect of being in space. The Biosphere 2 experiment was a type of analog mission in that it wasdesigned to simulate the experience of being confined inside a hermeti- cally sealed habitat with a small number of people for an extended period of time. Since the early 1990s, the number and diversity of space analogs have increased substantially. I came to the conference eager to meet some of the people who have participated in these simulated missions and to get a sense for what the experiences have taught them.
Soon after arriving at Biosphere 2, I met Tim Heilers, who was attending the conference as well. He was wearing a T-shirt that read “OCCUPY MARS.” We had barely gotten through the standard greetings when he asked me if I wanted to go to space.
“I guess so,” I replied with a shrug. I had the feeling my answer was less enthusiastic than he expected. “What about you?” I asked.
“Oh, yes,” Tim replied. “In a heartbeat.” Mars, more specifically, is where he said he wants to go. “Round trip, or one-way. It doesn’t matter,” he added. I asked him what it was about Mars that was so intriguing to him that he would want to leave everything behind and go there. “I’ve been watching StarTrek since I was a little kid,” he explained. “I’ve just always wanted to go.”
The conference had not yet begun, so we had some time to explore. The Biosphere 2 campus is located in the desert north of Tucson. The hulking steel and glass structure loomed in front of us with its unmistakable stepped glass pyramids and its iconic, mushroom-shaped tower. We followed the arrows painted on the sidewalk around the giant glass panels until they led to a door. We opened it, and stepped inside.
We were now in the dining room where the Biospherians had eaten their meals during the two years they were sealed inside. There was a table in the middle of the room with eight chairs. Next to the dining room, visible through an opening in one of the white walls, was a kitchen that looked like it could have been in a chic 1980s home. The combined kitchen and dining area felt spacious, with very high ceilings and floor- to-ceiling glass windows on two sides that overlooked the adjacent green- houses. We turned to the right and followed a hallway, along which were windows where we could look into a few of the crew quarters that had been preserved as a sort of museum. Each of the Biospherians had their own two-story private suite. On the first floor was a desk and a seating area with a 1990s-era television. A spiral staircase led up to the sleepingquarters. An orange jumpsuit was hanging from the stair railing. The decor recreated its original look, with a dark patterned rug on the floor and paintings on the walls. On the desk was a notebook, opened to reveal a daily journal entry.
Seeing the personal belongings in the room made it easier to imagine what it was like to live in such a unique place. Tim and I continued down the hall and up a few stairs toward a large set of windows that looked into an enormous greenhouse shaped like a tunnel with a vaulted, curved glass roof. This had been one of the three sections of the intensive agriculture unit, where the Biospherians had grown their food. They had cultivated more than 140 different crops, including wheat, rice, corn, barley, pinto beans, squash, tomatoes, potatoes, sweet potatoes, and carrots.
“Growing enough food to feed the eight biospherians on a little over half an acre was certainly one of the greatest challenges we faced,” wrote Biospherian Sally Silverstone, the food systems manager for the two-year mission. “We had put together a system combining the old with the new. For example, we had incorporated an ancient Chinese method of raising fish, rice, and water fern all together with our computer-driven system for controlling temperature and humidity.”
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As we continued our exploration of the facility, Tim seemed pensive. He told me that he has been thinking a lot about what he could do on Mars that would be useful.
“I built a Mars clock,” he said. I asked what that meant. “It’s a clock that tells the time on Mars,” he explained. I felt silly for not having understood the simple concept after remembering that a day on Mars is forty minutes longer than on Earth. “And I figured raising insects might be good,” he added.
“Have you done that?” I asked. He said that he had. He was rearing superworms—a kind of beetle larvae related to mealworms, only larger. He wasn’t able to sell them, at least not yet, but he thought it would be useful experience in case he ever gets the chance to go to space.
Like Tim Heilers, the Biospherians saw their experiment as preparation for space settlement. One of them, Jane Poynter, wrote in her memoir thatshe had wanted to be an astronaut as a kid. “However, I didn’t believe for an instant that it was a real option,” she wrote.4 But joining the crew of Biosphere 2 gave her a chance to see what life beyond Earth might be like. “We were designing Biosphere 2 for space colonization,” she wrote. “The overarching question was, is this possible? Can a life system that evolved on a planetary scale over billions of years be bottled?”
Poynter and the seven other Biospherians discovered that bottling the Earth’s ecosystems is a lot more challenging than they had anticipated.
Among the first problems was a food shortage. A few months into the mission, the Biospherians discovered that a mite infestation was killing their potatoes. The entire agricultural endeavor was designed to be pesticide-free, in part because of fears that killing insects in the agricultural areas could unintentionally harm the useful insects in the other biomes. Making matters worse, Arizona had unusually cloudy weather the first year of the mission. The steel and glass structure already blocked out some sunlight, which was further diminished by the cloud cover. Short win- ter days made the reduction in sunlight inside the enclosure even worse. Crop yields began to decline. The crew members began losing weight. While the team’s physician, Roy Walford, was an advocate of the health benefits of a low-calorie diet, even he was beginning to get concerned.
As energy levels sagged, so did morale. Inevitably, the crew started get- ting on each other’s nerves. “We only had close physical contact with seven other people for 731 days, 2,193 meals,” recalled Biospherian Mark Nelson.5 “Pretty quickly, everyone figured out tics, habits, and how to push each other’s buttons, not unlike dysfunctional family dinners. . . . Crew members deliberately provoked each other, at first earnestly and maliciously in attack and counterattack. Finally, in fun, we realized what was going on. Pushing one another’s buttons was a sport that could go on endlessly—and sometimes it seemed it did—since we knew each other incredibly well.”
But soon, a rift emerged that split the eight Biospherians into two equal- sized factions. Exhaustion and malnourishment had stoked the embers of a growing conflagration, but what ultimately caused it to burst into a raging inferno was a disagreement among the project’s administrators.
“The core issue was whether the primary goal was to work on maintaining as self-sufficient a closure as possible and improving the facility, including trying to produce all our food,” recalled Nelson.“ The alter- native was to lessen workloads by sending in food to give more time for research.”
The project management team was led by John Allen, the visionary who had conceived of the project, and Ed Bass, the Texas billionaire who had largely financed it. Now the two had different opinions about what should be prioritized. They had appointed a Scientific Advisory Commit- tee, which was now pushing for Allen to be replaced as the project’s top research advisor. The crew members took sides. It got ugly.
“Ten months after Closure, the four of Us would huddle at one end of the dining table for lunch, and the four of Them would either leave and eat elsewhere, or crowd together at the other end of the table,” Poynter wrote. Soon, the two groups of “Us” and “Them” could no longer make eye contact. The split between the two factions would last throughout the remainder of the mission. But then a new problem added to the already strained group dynamics: oxygen levels inside the enclosure were dropping.
The enclosure was designed to have enough oxygen given off by plants and algae and consumed by people and animals, while the carbon dioxide that the people and animals produce would be taken in by the plants and algae. As Tsiolkovsky suggested, that balance would be essential for a space habitat, and no previous closed-loop experiment had ever managed to get it quite right. The percentage of oxygen in Biosphere 2 dropped from 20.9 percent to 17.4 percent in the first six months—a level that was much lower than expected. If the same rate of oxygen loss continued, the Biospherians would soon be in serious trouble.
The odd thing was that the carbon dioxide levels weren’t as high as they should have been for such low oxygen levels. In a closed system, the two are tightly linked—as one goes up, the other goes down. At least it should. The search for the missing carbon dioxide had begun.
In the meantime, the oxygen levels continued to drop, reaching as low as 14.5 percent, and the crew members began to suffer. Some had sleep apnea, in which people briefly stop breathing as they sleep. Several had depression, which can be triggered by hypoxia. Roy Walford used the opportunity to capture the biological response to the declining oxygen by taking regular blood samples from crew members. He noted an effecton his own cognitive abilities. When he found he could no longer do basic arithmetic, he had to relinquish his role as lead medical officer.
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Eventually, the missing carbon dioxide was found—it was hiding in the basement.
The concrete floor, walls, and columns of the lower levels of the structure where all the mechanical components were housed were absorbing large quantities of carbon dioxide. Too much, in fact. Some carbon dioxide was expected to be absorbed by the untreated concrete, but the quantities they found in the concrete sample cores were far beyond anticipated levels. Now the question was, where was all the excess carbon dioxide in the concrete coming from?
The culprit turned out to be bacteria. To build their biomes and farms, the project managers had included soil dredged from a local pond combined with organic peat and compost. The result was 30,000 tons of soil that was rich in nutrients as well as microbes. That was helpful for jump- starting the nutrient cycles that happen in nature, and for getting plants to grow, but the high number of bacteria had unintended consequences. The bacteria were respiring like people and animals, taking in oxygen and giving off carbon dioxide. But rather than being taken up by plants, which could make more oxygen, the excess carbon dioxide was getting soaked up by the concrete. Because carbon dioxide contains oxygen, a large amount of the oxygen in the enclosure was being taken out of circulation by the concrete. In natural ecosystems, minerals like limestone absorb carbon dioxide.
Over millions of years, the carbon and oxygen get returned to the atmosphere as these rocks undergo natural cycles of erosion, weathering, and plate tectonics. That wouldn’t happen in Biosphere 2—at least not on a timescale that would be helpful to its inhabitants. While the problem could be solved for future missions simply by coating the concrete with a chemical sealant, in the short term it was an issue that needed to be dealt with.
Interestingly, Walford’s blood tests showed that the crew was not adjusting to the lower oxygen levels the way people normally do when they travel to high altitudes in the mountains, where the thin air means there is less oxygen. A typical response in people coming from lower altitudes is for the body to start making more red blood cells when it senses that oxygen levels are low. For most people, it takes about five or six days for there to be enough new red blood cells to notice a difference, which is why people can usually adjust to high altitudes after about a week. Walford and his medical colleagues suggested that the crew members were not making new red blood cells in response to the low oxygen levels because their bodies didn’t have enough energy to do so due to their restricted diets. They were in rough shape.
As crew health became a serious concern, the decision was made to add supplemental oxygen. The impact on the crew was immediate.
“It was a sense of well-being to breathe deeply and not feel like I needed another breath almost immediately,” recalled Biospherian Linda Leigh.
“We were all madly laughing and running,” remembered Mark Nelson. “Then it struck me, I haven’t heard the sound of running feet in months. Friends said watching us biospherians work was like seeing a dance in slightly slow motion. With the reduced-calorie diet and lowered oxygen, people were economical in their movements. There simply wasn’t extra energy to burn.”
The boost in oxygen was a relief, but there was still a shortage of food. Eventually, the crew were forced to eat seeds that had been set aside for future planting, along with their emergency grain supply. This meant they were eating food that they had brought with them, not just what they grew, as was planned. Making matters worse, it threatened to diminish the amount they would be able to grow in the future. This was a further step away from their goal of creating a self-sustaining enclosure, but at least it meant they could continue to stay inside.
But different opinions about whether or not they should eat the seed reserves—and about how transparent they should be with the media about their ultimate decision to do so—drove a dagger through the heart of the project team that ultimately was irreparable. All the members of the Science Advisory Council resigned. Inside the enclosure, the brewing feud among the Biospherians reached its climax. Poynter recalled the moment when the tension boiled over:
“On Tuesday morning I was putting fodder in the animal bay when Gaie walked over to me,” she wrote. “I watched as she collected a big wad of saliva in her mouth and spat in my face. She turned and walked away without a word. Forty-five minutes later I was walking up the spiral stairs during break time when Laser stopped on the stairs next to me and spat a mixture of saliva and peanut goo in my face.”
Somehow, despite all the animosity the crew managed to hold out for the duration of the mission. All eight Biospherians walked out of the airlock exactly two years and twenty minutes after they had sealed them- selves inside. The two factions were still not on speaking terms.
“We suspected group dynamics might be one of the more challenging aspects of Biosphere 2,” wrote Mark Nelson. “Turns out, we were right.”
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Tim Heilers and I continued our exploration of Biosphere 2, entering a door on the ziggurat-shaped glass structure that housed the desert biome. A boardwalk wound around the artificial rocks, where cactus, succulents, and desert shrubs grew in the sand. The walkway curved around and up a flight of stairs, and I noticed the vegetation getting thicker as the path leveled off. We reached a cliff that overlooked a miniature ocean, complete with a small beach. A solitary coconut palm tree had grown up from the sand to the top of the sloping glass wall, its fronds plastered to the glass as if trying to escape.
We stood there for a while admiring the view. Tim was quiet and had a distant look in his eyes. I asked him if he had been a part of any analog space missions. He had not—at least not yet. But he had served as a sonar technician on a nuclear submarine in the Navy. That struck me as pretty good practice for being in an isolated, confined, and hostile environment much like in space. I said so, and Tim agreed.
Compared with a crowded submarine, the Biospherians had had quite a lot of space—combining all the indoor areas, it came to more than 17,000 square feet per person. Still, it often felt confining, especially as the rift between the crew members deepened. “With nearly palpable hos- tility hanging in the Biosphere like a toxic cloud, Taber and I looked for ways to escape,” Poynter recalled. “Sometimes we hiked the two hundred feet down the stairs and through the basement to the beach and sat looking out through the spaceframe at the stars. We would search for Mars in the night sky and contemplate how different things might be if our Biosphere were suddenly transported there and we were looking not at the tiny red speck of Mars, but at the bluish dot of our home planet. Per- haps on Mars, with the safety of home at least forty-eight million miles away, we would have been able to pull together. But then again, perhaps not. I wondered if people are really meant to be enclosed in small spaces, even as large, beautiful, and varied as Biosphere 2. The human species, after all, did not evolve indoors.”
The same question had brought me to the Analog Astronaut Conference, and I was eager to find out what lessons had been learned in the three decades since the tumultuous Biosphere 2 experiment. Tim and I made our way through the final enclosed portion—the moist, green rain- forest biome—before emerging once again into the dry desert air outside. All of us conference attendees were staying adjacent to the original Bio- sphere facility in colorful adobe-style casitas.
I met my roommate, Donald Jacques, a sixty-six-year-old Air Force veteran and former computer programmer who now works as a handy- man. He told me he was building his own space analog out of a bus that he has lived in full-time for over a year. He calls it the MASH, short for Mobile Analog Sustainability Habitat. Donald eagerly explained how he uses black soldier fly larvae to break down solid human waste and convert it into soil. The extra flies and larvae get fed to his chickens. The chicken waste, in return, gets broken down by the fly larvae. His goal, he said, is to create a sustainable, self-enclosed system as a prototype for a space settlement. I was impressed by the effort and dedication. It sounded like a mini-Biosphere 2 on wheels.
“What’s your motivation?” I asked him.
Donald told me that he wants to visit the Moon, then Mars, which he thinks will be possible soon. From Mars, he wants to travel to places beyond, like the moons of Jupiter and Saturn, ultimately to destinations outside our solar system. He sees the work he is doing on the mobile habitat as his ticket to the stars.
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The idea that participating in analog simulations can prepare a person for actual spaceflight is embodied by the Analog Astronaut Conference’s matriarch and cofounder, Sian Proctor. Like many in the analog astronaut community, Proctor had been trying to get to space her entire life. She was born on Guam, where her father was working at a tracking station as part of the Apollo program.
I had seen her speak at the Humans to Mars Summit in DC the year before. “I’m a Moon celebration baby,” she had said. “I was born eight and half months after the first Apollo landing.”
Growing up around the space industry in the 1970s and 1980s, Proctor dreamed of becoming an astronaut herself. “As a kid, I didn’t realize there weren’t yet any black astronauts,” she said. So, in her thirties she applied to be a NASA astronaut, and in 2019 she made it all the way through the selection process until the final step.
“It came down to the yes/no phone call,” she said.
The call came, but it was a no. Disappointed but undeterred, Proctor continued to pursue her passion through analog space missions. The following year she joined a two-week analog mission at HI-SEAS, a facility located at 8,200 feet above sea level on the slopes of Mauna Loa. She had done her first analog mission there—in fact, she was part of the first ever HI-SEAS analog simulation in 2013. She also did two-week simulations at the Mars Desert Research Station in Utah and at another analog facility in Poland.
Then, one day, she got the call she had been waiting for her entire life. It was Jared Isaacman, an entrepreneur financing a mission to space called Inspiration4 that was slated to fly a crew of four people on a SpaceX rocket. It would be the first-ever all-civilian mission to orbit the Earth. He invited Sian Proctor to join him.
The Inspiration4 crew orbited the Earth for four days in 2021, with Proctor as its pilot. That made her the first female commercial astronaut pilot and the first African American woman to be a pilot on any space- craft. She became something of a celebrity in the space community, and the role model for every analog astronaut hoping that their dreams—like Sian Proctor’s—will somehow come true.
I asked Proctor if the analog missions had been helpful preparation for the real thing. “Oh yes,” she told me. “They taught me important lessons about myself and my capabilities, as well as my limitations. And they taught me about how to work well in a team,” she said.
NASA sees analogs as useful as well. It operates several of its own, including two at Johnson Space Center. HERA, the Human Exploration Research Analog, is a 650-square-foot habitat where crews of four spend up to forty-five days on simulated space missions. The 1,700-square-foot CHAPEA analog, which was 3D-printed to simulate a habitat on Mars, completed its first year-long mission with a team of four in July 2024. NASA also operates an underwater analog in the Florida Keys, called the NASA Extreme Environment Mission Operations project, or NEEMO. Other governmental space agencies operate their own analogs, including a series of hermetically sealed habitats at the Institute of Biomedical Problems in Moscow that has been used by the Russian space agency, ROSCOSMOS, as well as the European Space Agency.
A clear advantage of analog studies is that analogs are much less expensive than going to space. That means that a lot more analog studies can be conducted and that they are accessible to a wider range of people. Some analog facilities can be modified to test the effects of particular aspects of a space mission. For example, a communication delay of around twenty minutes can be implemented to see what the effect is on the crew of having a delay similar to that between Earth and Mars.
Psychologist Nick Kanas has summarized the sources of psychological stress that come with prolonged spaceflight that can be examined using analog missions. They include the stress of isolation and confinement, boredom from having too much free time and too little stimulation, repetitive work and monotonous days, and conflicts and disputes with fellow crew members. Some interesting results of these studies include findings related to the size and composition of the crew. In general, the larger the crew size, the less likely that any one crew member feels isolated. An odd number of crew members makes it easier for the group to come to agreements, since it’s impossible to split an odd number into two evenly sized factions, as happened to the Biospherians.
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One type of stress that analogs can’t always simulate is the life-threatening danger from the extreme environments of space. If something goes seriously wrong in a simulated mission, the crew can simply leave. Simulations are certainly safer for the crew than being in an environment that more accurately recreates the harshness and isolation of being on the Moon or Mars. But, on the other hand, the fact that the crew know they can leave if there’s an emergency must have an effect as well.
Angelo Vermeulen, a Belgian biologist, artist, and engineer, served as commander of the first analog mission at HI-SEAS along with Sian Proc- tor. He told me that he had a hard time imagining he was on another planet when he was very well aware that he was in fact in Hawaii.
“Just looking outside and seeing a blue sky, and a bird passing by—it’s not Mars,” he said. “It’s difficult to maintain the belief you’re pretending to be on Mars for such a long time.” Although the location of HI-SEAS is relatively remote, in an emergency it would be possible to just step out- side the facility. Even though the crew wore simulated spacesuits to keep up the feeling that they were on Mars, at the end of the day they all knew the suits weren’t actually necessary.
“I think it’s different when you have an underwater station,” he offered. “Probably that is a little closer to feeling like you’re surrounded by a threatening and hostile environment. Of course, if you’re in Antarctica that’s a different story. Then you’re really in a hostile environment and also very remote where there is no help available. I think that would psychologically be very different.”
Indeed, studies of people living and working at polar outposts have provided some of the best analogs for deep space missions. Antarctica in particular serves as the place on Earth that most closely resembles the extreme conditions on the Moon or Mars. While there are no permanent settlements on the white continent, there are dozens of permanent research bases. Some, like Palmer Station, can be accessed year-round by ship. Many others, however, are only reachable during the summer season. The largest station in Antarctica, McMurdo, houses some 1,500 people in the summer when it can be reached by ship. It also has landing strips for airplanes and helicopters, but there are no real transportation options during the winter when it’s nearly always dark and temperatures average around −18 degrees Fahrenheit with plenty of snow. The roughly 200 researchers and staff who spend the entire winter at McMurdo experience true isolation in the most extreme conditions.9
Seasonal affective disorder is common at McMurdo, afflicting more than a quarter of those who overwinter. Some develop a more extreme version known as “winter-over” syndrome that includes having a hard time focusing and can include becoming irritable or even aggressive. Some develop a blank look known as the “Antarctic stare.” About one out of every twenty people who overwinter in Antarctica develop true psychiatric disorders.
Another group of people who experience both the isolation and confinement of space with a truly extreme and hostile environment are those who serve on nuclear submarines, like Tim Heilers. Nuclear submarines can remain underwater for months at a time, and being submerged in the deep sea certainly qualifies as being surrounded by a hazardous environment. While some studies have been conducted on the group dynamics and psychology of submariners, their being part of military operations makes it difficult for researchers to have the same kind of access as in many space analogs.
As extreme as the Antarctic bases and nuclear submarines are, even these lack some of the conditions that make space so hazardous, like reduced gravity and high radiation. On the other hand, that allows researchers to study the effects of individual stressors, such as being in a confined environment or having limited social interactions, which could lead to finding ways to help mitigate them.
One of the most salient lessons from the world of analogs seems to be that regardless of whether they’re in a submarine, a polar research station, or a simulated Martian habitat, it makes a big difference whom you seal up inside a small space for a prolonged time. Psychological screening, which can include tests, interviews, and a review of personal and family history, can minimize the chances that a person more likely to develop mental health issues gets included in a crew. But in addition to selecting out people with certain characteristics that might become problematic, selecting in people with beneficial personality traits can also be helpful. In general, people who are highly motivated, deal with stress in healthy ways, and work well with others tend to do well in both analog and real space missions.
But individual traits alone are only part of the recipe; it also matters how they work together as a team. It is difficult to know how well any group would do until they are actually faced with challenging conditions. For this reason, training and group activities in advance of a mission are often used to evaluate candidates and build team cohesion.
For example, Angelo Vermeulen told me that prior to their four-month HI-SEAS analog mission, he and his crew members spent two weekstraining at the Mars Desert Research Station in Utah. “Interestingly, the rules, the social dynamics—everything that we used in HI-SEAS—was developed in Utah,” he said. “You come together as a group, you establish a kind of relationship with each other and you don’t really change that anymore. It’s a typical group dynamic that sets in pretty quickly.”
Still, there is no guarantee that even a carefully selected and trained crew is going to work well together. The Biosphere 2 crew had undergone quite a bit of training and work together before beginning their two-year stint inside the sealed facility in Arizona. But that didn’t prevent the team of eight from deteriorating into a dysfunctional pair of factions who were more likely to spit on one another than to have a conversation.
At one point during her time inside Biosphere 2, in the midst of all the hunger, fatigue, and frustration, Jane Poynter recalls a moment of peace and clarity while pulling out weeds in the desert biome. The idea that she controlled which plants lived and which one died struck her as an awe- some, almost Godlike, power.
“I wondered whether Biosphere 2 was an attempt at the ultimate expression of control—the bottling of nature to thoroughly conquer it once and for all,” she mused. “If we can cage nature, tame it, and train it to work for us, then we have overcome a distinct glitch in our quest for species immortality. After all, every living thing’s primary innate goal is to have offspring to perpetuate the species. Biospheres simply promise to take that one step further: the species can ensure that it has an environment fit to inhabit.”
The idea made enclosures like the one she was locked inside suddenly seem like a very real possibility for future space settlements. “At that moment, fantasies of biospheres floating through space, keeping cities of humans alive, seemed perfectly plausible,” she recalled. “Whether future space was to be populated with sterile, overcrowded tin cans or biospheres, I only hoped that the people and their cultures would have evolved to get along better than we had.”
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One psychological aspect of real spaceflight that is not replicated by any analog simulations is the profound impact of seeing Earth from space.
“It’s hard to describe the experience of looking down at the planet. I feel as if I know the Earth in an intimate way most people don’t,” wrote astronaut Scott Kelly after his year aboard the International Space Sta- tion. “One of my favorite views of the Earth is of the Bahamas—a large archipelago with a stunning contrast from light to dark colors. The vibrant blue of the ocean mixes with a much brighter turquoise, swirled with something almost like gold, where the sun bounces off the sandy shallows and reefs.”
Unlike in a ground-based analog, the awe and wonder of being in space and seeing the Earth from the outside can help to offset some of the challenging aspects of being confined and isolated with a small group of other people. “Sometimes when I’m looking out the window it occurs to me that everything that matters to me, every person who has ever lived and died (besides the six of us [on the International Space Station]), is down there,” Kelly wrote. “Other times, of course, I’m aware that the people on the space station with me are the whole of humanity for me now. If I’m going to talk to someone in the flesh, look someone in the eye, ask someone for help, share a meal with someone, it will be one of them.”
In the 1980s, space philosopher Frank White created a name for this shift in perspective that astronauts often report having while in space—he called it the “overview effect.” The idea came to White while flying on an airplane. “As the plane flew north of Washington, D.C., I found myself looking down at the Capitol and Washington Monument,” he wrote in his 1987 book about the idea.14 “From 30,000 feet, they looked like little toys sparkling in the sunshine. From that altitude, all of Washington looked small and insignificant.” Looking out over the landscape also gave him a sense of how interconnected everything is. “From the airplane, the message that scientists, philosophers, spiritual teachers, and systems theorists have been trying to tell us for centuries was obvious: everything was interconnected and interrelated, each part of a subsystem of a larger whole system,” he wrote.
White wondered whether being even higher would create an even more profound effect. He interviewed astronauts who had been in Earth orbit or to the Moon, and discovered that many of them said they had indeed experienced a major shift in perspective. White discovered a talk given by Apollo 9 astronaut Rusty Schweickart in which he described his personal experience orbiting the Earth in March 1969: “When you go around the Earth in an hour and a half, you begin to recognize that your identity is with that whole thing. That makes a change. You look down there and you can’t imagine how many borders and boundaries you cross . . . you don’t even see them from where you see it, the thing is a whole, and it’s so beautiful,” he said.
Seeing this view of the world quite literally changed Schweickart’s worldview.
“You look down and see the surface of that globe that you’ve lived on all this time, and you know all those people down there and they are like you—they are you—and somehow you represent them. You are up there as the sensing element, that point out on the end, and that’s a humbling feeling. And somehow you recognize that you’re a piece of this total life. That becomes a special responsibility and it tells you something about your relationship with this thing we call life,” he said.
White later interviewed Schweickart, who expanded on his previous insights. Other astronauts told White similar things. Many said they became more interested in protecting the fragile planet we live on after seeing it from outer space.
“Some parts of the world are so blanketed by air pollution that they appear sick, in need of treatment or at least a chance to heal,” wrote Scott Kelly. “The line of our atmosphere on the horizon looks as thin as a contact lens over an eye, and its fragility seems to demand our attention.” Hearing from astronauts convinced Frank White that he was onto something. While images from space could have an effect on people—the Earthrise photo taken by Apollo 8 astronaut Bill Anders while orbiting the Moon helped to launch the environmental movement —experiencing the view personally seemed to be much more impactful. White thought about the long-term consequences of the overview effect, not only for individuals but for all of humanity. If each person who goes to space comes back transformed, he reasoned, imagine what would happen once many people have been to space.
And imagine what would happen to people who leave our planet to live off-world permanently—and what would happen to their children.
I met Frank White at a space conference in Austin called New Worlds. I sensed he had become a sort of patriarch of the space community. Itwas clear that he was widely respected among the conference attendees, who spoke of the overview effect with the sort of reverence normally associated with religious doctrine. We spoke again by Zoom a few days later once he was back at his home in Massachusetts. Given how much of White’s work focused on the psychological effects of actually being in space, I wondered what he thought about analog missions.
“I think the people who are doing the analogs are the best candidates for large-scale space migration,” he said. “They’re not focusing on ‘I want to get on a rocket.’ They’re focusing on ‘I want to know how to function in a small team out there once I get my chance.’ And I think that’s wise.” The conversation soon turned to the topic I most wanted to ask him about, something we had both thought deeply about: the long-term consequences of space settlement. White said he considered the topic so important that he made it the subtitle of his book—The Overview Effect:
Space Exploration and Human Evolution.
“The more I worked on the book, the more evolution became impor- tant,” he told me. White was quick to point out that he is not a biologist, but based on his understanding of evolution he had come to some con- clusions about how space exploration and migration could be a catalyst for changes that are both cultural and biological. “It seemed really, really clear that space exploration would trigger evolution,” he said.
I nodded. The question, we both agreed, was how people in space would evolve.
Excerpted from Becoming Martian: How Living in Space Will Change Our Bodies and Minds by Scott Solomon, published by MIT Press, ©2026 by Scott Solomon. All Rights Reserved.
