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Elah Feder: On September 25, 1991, 2,000 people gathered in the Arizona desert for a dance party.
Mark Nelson: With stilt walkers, with fireworks, there was a great dance troupe, Harlem. We had part of the cast of Cheers, that TV program, the Boston bar.
Elah: For Mark Nelson, it was a big night, and not just because he got to party with Woody Harrelson. This would be his last outing for a very long time. What are you feeling? Are you feeling anxious at all about the next morning, or?
Mark: Yeah. Well, I think more excited than anxious. I mean, to me, it was, you know, there was no way that this thing would fail.
Elah: This thing that could not fail? Biosphere 2, a nearly airtight glass complex in the foothills of the Santa Catalina Mountains, about an hour north of Tucson. The next morning, Mark and seven others would go inside, and if all went according to plan, they wouldn’t come out for another two years. I’m Elah Feder, and this is Atlas Obscura, a celebration of the world’s strange, incredible, and wondrous places.
This is an edited transcript of the Atlas Obscura Podcast: a celebration of the world’s strange, incredible, and wondrous places. Find the show on Apple Podcasts, Spotify, and all major podcast apps.
Elah: In the fall of 1991, eight people embarked on an epic experiment. For two years, a small crew would live inside Biosphere 2 in Arizona, along with thousands of carefully selected species, kind of like a Noah’s Ark on dry land. And if all went well, Biosphere 2 could be an idyllic home, a three-acre glass palace teeming with life, where they would tend to a small rainforest, grow fresh fruit on their organic farm, and snorkel among tropical fish in their mini rectangular ocean. But not all went well.
Mark: You know, we used to have meetings where we’d go in a room and people would say, What’s your top five nightmares about what could happen in Biosphere 2? What could go wrong?
Elah: A lot, as it turns out.
The morning of their big send-off, Mark Nelson and his fellow Biospherians stood outside the Biosphere 2 airlock, smiling and waving at the crowd. They were dressed in navy blue jumpsuits that made them look like they were on Star Trek. It was something that a Hollywood costume designer had come up with. For a few years, hype had been building around the $150 million facility in the Arizona desert. A lot of reporters weren’t quite sure what to make of the people running the project. It was privately funded, largely by a Texan billionaire, and promoted as a science experiment. But most of the Biospherians didn’t have advanced degrees. Plus, they seemed kind of like hippies. Their leader was an engineer and beat poet who’d once gone by the pen name Johnny Dolphin. Several articles had described him as charismatic, which seemed like code for cult. Who were these people? Over the months to come, that uncertainty would harden into scorn and ridicule. But back on that first day in September, the sun was shining, and 1,500 people had come out to support them. Even Mark’s mother, not always the biggest fan of his life choices, seemed to have come around, now that Biosphere 2 was a worldwide sensation.
Mark: She was the mom of one of the Biospherian crew, and they treated her like a VIP when she came on site. So I think that redeemed everything.
Elah: Mark was supposed to be a doctor.
Mark: That’s the requirement for young men in my family. And I’m thinking, I don’t want to do that.
Elah: This was in the 60s, the era of free love, Woodstock, and flower power. No way was Mark going to get a job when he graduated and live his life on the weekends. Instead, he hooked up with a group of people setting up a ranch in New Mexico. And yeah, in a lot of ways, they were absolutely the hippies some media would later make them out to be. But if these people were hippies, they were damn effective ones. They quickly got their ranch up and running, and then immediately they were like, okay, next challenge, let’s build a ship. Not a boat, mind you, a proper 100-ton ship. And though none of them had actually built a ship before, the ship did not sink. Soon, they were sailing all over the world. By this point, they’d established themselves as the Institute of Ecotechnics, dedicated to kind of everything: art, science, nature, all of it, which is not usually a recipe for success. But this group, they just kept taking off one challenge after another. So after a ranch and a ship, what next? A biosphere, of course.
Mark: We called it Biosphere 2 to invite the question, where is Biosphere 1? Was that a project that you, you know, so screwed up that now you’re doing two? No. Biosphere 1, here’s the great secret, guys, that’s the world that you live in.
Elah: Biosphere 1, that’s everything that you know and love. It’s the land, the sky, the sea, and all the creatures within. The Institute of Ecotechnics was going to create a mini-biosphere, with plants and animals inside, ideally forming functioning ecosystems. So my first question before I got deeply sucked into this story was, why? And also, if I’m honest, so what? Your plan is to live inside a big, beautiful glass building? That doesn’t seem that hard. You’re basically living in a fancy greenhouse. Except Biosphere 2 wasn’t a greenhouse, however much it looked like one. It was nearly airtight. Obviously light and heat could still come in, but in terms of matter, it was basically a closed system. And inside a closed system, you are completely dependent on the life around you. All your oxygen is coming from the plants and algae photosynthesizing. And think about your waste. If nothing is going in or out, you could soon find yourself living in a vat of sewage. Everything needs to be recycled. So why would you do this to yourself? Well, if you figure out how to make a small, closed system work, you’d have a better understanding of the bigger biosphere we all live in. And you’d also have a blueprint for life in outer space. So think, instead of bringing freeze-dried food and heavy tanks of oxygen on a 10-year mission, hoping it lasts, you could bring plants and algae that feed you and continuously supply clean, oxygen-rich air. This was a key promise of Biosphere 2, a model for the future beyond this planet, possibly a very beautiful one. Mark was desperate to be part of it. This was going to be his team’s most ambitious project by far. They’d secured millions of dollars in funding, thanks to a very convenient friendship with a Texan billionaire, a longtime fan of the Institute of Ecotechnics. But only eight people could be chosen to actually live in the biosphere. That’s all it could support. So Mark signed up, completed the training, and then he waited, and waited, as one person after another got chosen by the project’s management. Finally, when there was just one slot left, he got the call.
Mark: And it took me about a nanosecond, you know, the yes came out even before my brain—it’s kind of like, will I join the crew? Yes. You don’t even need to finish the sentence.
Elah: In our conversation, Mark often skipped around in time to life inside Biosphere 2 and everything he’d learned since. But I wanted to know, what was he thinking right then in the summer of 1991 before any of it happened? Did he have any idea what he was getting into? Did he think he was going to be living in a little paradise with seven of his best friends? Because you know, obviously the reality of the thing is always going to be different than what you’ve imagined. In that moment, what were you picturing?
Mark: Well, I was picturing that every day was going to be a challenge. I mean, I think all of the eight of us had no expectation that we were going to last in there for two years. No way. There were so many things that, you know, even a very minor fire would have meant that we would have to leave.
Elah: The morning they entered Biosphere 2 was pure excitement.
Mark: Yeah, I’m shaking hands with people from the project. You know, we’re doing an appearance for the press. And then we’re in a biosphere that’s way quieter than I’ve ever experienced. And the realization that we are the only humans in there starts to kind of become real.
Elah: The new housemates included four women and four men. Most were in their 20s and 30s. Mark, at 45, was the second oldest. There were two couples in the group, and Mark wasn’t one of them. So he liked to imagine he was entering a Zen monastery for the next two years. Their new world was divided up into distinct biomes. There was a small rainforest inside a glass pyramid on the north end of the complex, beside it a 500-foot-wide ocean, basically a giant saltwater aquarium complete with coral reef and sandy beach. Next to that, a savanna grassland, then there was a marsh. All of this had been meticulously planned out with a team of experts. Each biome had its own climate and technical challenges. Like, the rainforest had to be moist and temperate. The artificial ocean needed vacuum pumps to circulate nutrients, but without sucking up all the fish and plankton. Oh, and one more thing: Since the building was tightly sealed and all glass, a hot, sunny day might make it explode. So the complex had two huge lungs, basically big caverns with flexible rubber ceilings that would rise and fall with air pressure. To maintain this thing would take a lot of work from both the Biospherians inside and their support team on the outside. So once they were inside, they got to work. Everyone had a different job. One person was in charge of the lab. The oldest in the group, Roy Walford, he was actually a respected medical researcher, and he would be monitoring the crew’s health. One of Mark’s main jobs? Sewage, which he was not remotely bitter about. Ocean waste was cleaned and recycled by their wetlands, with Mark’s help. Inside Biosphere 2, they weren’t totally cut off from the world. They couldn’t leave, but they were in regular communication with Mission Control, aka the scientists, engineers, and administrators supporting them from the outside. And during the day, tourists would come and stare at the Biospherians through the glass.
Tour Guide: All right, we have five wilderness biomes inside and two man-made biomes.
Elah: Thousands came by, school groups, families, tourists, just out for a day of fun, watching people living inside a terrarium.
Tour Guide: Okay, let’s continue on, and we’ll start here with the rainforest.
Elah: One time, even Jane Goodall came to observe. One Biospherian said she seemed to be studying them like primates in captivity, which they kind of were. Depending on how much you enjoy being on display, life in Biosphere 2 sounded pretty fun. But just keeping the system in balance was a daily battle. At one point, they had an explosion of cockroaches thanks to some stowaways that snuck in before the doors shut. A much harder problem? Food. Everyone put in a few hours a day working the half-acre farm, the center of the complex. It was largely a vegetarian diet, though they also had pigs, chickens, and adorable pygmy goats whose fates I really don’t want to contemplate. Cooking was on a rotating schedule, and people worked very hard to make their meals as delicious as possible. They brewed rice beer, made cheese and bread, and baked elaborate banana cakes for people’s birthdays. But when you’re using the same handful of ingredients over and over, you start to get bored. Apparently, one person’s specialty was pureed leafy greens until people were like, enough, man. And they quickly found that for all their hard work, they just weren’t producing as many calories as they wanted.
Mark: Everybody in there lost significant amounts of weight. I was 45-ish when I went in there. I was weighing what I did when I was 19.
Elah: Roy, the doctor, he’d actually made a name for himself studying the health benefits of calorie-restricted diets. And according to his assessment, the group was still very healthy. But that did not mean they were having fun. And as hunger took hold, tensions rose.
Mark: Some people were saying, you know, screw this. Let’s bring in food. Let’s get back to a normal diet. And then, you know, we’ll have more energy to do research. So that was kind of a polarizing thing. Didn’t get to fist fights, but a genuine difference of opinion. My opinion was, let’s carry out this experiment as originally envisioned and see how ingenious we could be.
Elah: In the end, they decided, no new food. But this division between the experimental purists and the people who just wanted to make life livable in there, that wouldn’t go away. Anyone who’s had roommates knows how hard it can be to live in close quarters. Now imagine having seven roommates who never go out, and neither do you. And you’re hungry all the time. And your roommates decide how much food you get. You’re going to have conflicts. Like, Mark felt that when the doctor cooked, his meals were suspiciously light. So he angrily confronted him. Roy denied doing anything wrong. Another time, banana cake was stolen from the fridge. The culprit didn’t take the whole piece, just carefully removed half of it. Like somehow that meant no one would notice. The team decided to keep the banana storage room locked, and just couldn’t trust themselves. Still, the Biospherians seemed to get through most of their conflicts, and make life work inside Biosphere 2. Maybe not always as friends, but at least as teammates. And then, they started losing oxygen. They first noticed the problem about six months into the experiment.
Mark: We had scheduled that there was going to be a complete air analysis. And I remember, you know, Taber was a little bit ashen.
Elah: That’s Taber MacCallum, at 27, the youngest in the crew. He was responsible for monitoring the air quality. And he would have caught the issue earlier, but apparently an automated oxygen sensor had failed. So they didn’t realize this. If oxygen was dropping, it meant that photosynthesis and respiration were out of balance. Almost all of the oxygen on our planet comes from photosynthesis. But respiration consumes it. So every time you breathe, you suck up oxygen and release carbon dioxide. Same goes for every other living thing. Too much respiration, and you’re eating up too much oxygen, and you have problems. Now, me in this situation, I would have been busting through that airlock and rolling around in free oxygen like a pig in mud. But these guys, they didn’t sign up for Biosphere 2 just to bolt at the first sign of trouble. They decided to stay put. It wasn’t an emergency—yet.
They’d started with a healthy 21 percent oxygen, same as outside. By the spring, they were down to about 17 percent, which is still livable. It’s on par with some high-altitude cities. But they definitely didn’t want it to get worse. The obvious answer was to add plants. That had actually been a major effort of theirs from the start, planting everywhere they could. They even converted their stairwells into gardens. More gardens meant more oxygen and more food. But it wasn’t enough. Months passed. By the fall of 1992, oxygen had dropped below 16 percent. And at that point, three crew members developed sleep apneas. Their bodies, starved for oxygen, would snap awake at night. The team came up with a workaround. They’d pipe in oxygen from the lab into those bedrooms. And it bought them a bit of time, but it didn’t fix the problem. Oxygen kept falling. The old divisions came back. Some argued it was time to bring in some new oxygen. But that wouldn’t look very good. Biosphere 2 was supposed to be a closed system. And they’d been accused of cheating more than once. The first incident actually took place just a few weeks into the experiment. Jane Poynter, the second youngest in the group, she’d been using a rice hauling machine when she accidentally severed the tip of her finger nearly to the base of the nail. So they decided to send her out for surgery. She was only gone for a few hours, but a rumor spread that when she got back, she smuggled in supplies to help them slip in and out of the airlocks undetected. The biospherians denied this. Then there was the time they actually did pump in air. This confused me when I first learned about it. I’d been reading so much about this great oxygen debate and then discovered, wait, they already brought in air?
So this is what happened: Biosphere 2 was remarkably well sealed. Apparently much better than some spacecrafts, but a tiny bit of air still leaked. And early on in the experiment, they wanted to calculate exactly how much. The lead engineer on the project explained that as part of that test, they purposely let internal air pressure rise a bit, which increased the rate that air leaked out. Then they had to replace what had leaked out, and so they let some outside air in again. That fresh air amounted to about 10 percent of the total volume of the complex. So this was a one-time test, and it actually demonstrated how tightly sealed the structure was. But to some of the press, this seemed like cheating, just a basic violation of the terms of the experiment. Can you still call this a closed system if you’d let in fresh air? Mark’s thinking was yes, actually. That hard drop in oxygen, the dramatic weight loss, all of that proved that even if Biosphere 2 wasn’t perfectly closed, it definitely wasn’t open, and a nearly closed system could still teach them a lot. So he wanted to stick to the plan. No new food, no new air. Or at least no new new air. But on the other side was team Let’s Not Kill Ourselves. Why don’t we keep living here, do the research, and like, still breathe at the same time? It all came to a head one day when Roy, the doctor, was trying to add up a string of numbers and realized he couldn’t do it.
Mark: Because cognitive confusion is also a side effect, and that’s when he was, you know, people on the outside were like, come on, you should stop this. You need to inject oxygen. That’s when Roy said, okay, enough is enough.
Elah: And so, 16 months into the experiment, when they were more than halfway through, they made the call: Bring in the oxygen. It arrived in refrigerated trucks on January 14, 1993. It was around 9 p.m. The Biospherians gathered in one of the big dome lungs where it was first pumped in, and they felt it right away. The last few months had taken a toll on their bodies. They’d become lethargic, started moving in slow motion. Now, as the oxygen flowed in, Mark saw something he hadn’t in a very long time. People were running around. People were laughing.
Mark: Oh my God, I don’t know what to say. It’s like, you know, we take so much for granted, and we take oxygen for granted. I vowed that after that I would never take it for granted, but hey, you know, it’s been a while.
Elah: And so, the Biospherians were able to survive the rest of their time inside. Eight months later, they stepped out triumphantly. It was two years and 20 minutes after they’d first entered. On their return, they were once again greeted by a big crowd of supporters. The Institute of Ecotechnics shared some old footage from the event, and you can see all of these people getting up to give them a standing ovation.
Mark: I’m up there, and my God, feeling the energy of other human beings without a glass between us, looking at the horizon, the beauty, the beauty of the Sonoran Desert, and the air. The air is so thin.
Elah: Mark’s friends and family were there. Jane Goodall, too. This time to welcome them back to Earth.
Jane Goodall: It’s one of the magic moments of history, and we’re sharing that moment together. Thank you.
Elah: Afterwards, Mark and the others were taken away in golf carts for medical exams and their first meal in two years prepared by other people. And they were feeling pretty fantastic. They’d made it. But not everyone saw it that way. Hadn’t they promised to do this without any outside food, air, or water? Well, they brought in air. And to a lot of people, that meant they’d failed. But Mark thinks this misses the point. Biosphere 2 was an experiment.
Mark: To me, that was one of the triumphs of Biosphere 2. It showed that really unexpected stuff would happen, and we could engage enough science to really delineate why it happened and take corrective measures. If nothing unexpected happened, it’s like, we should have just made a computer simulation. Why go to all that trouble and expense?
Elah: The point of an experiment is to learn. And they did learn. Dozens of papers came out of the project. Papers about engineering, ecology, agriculture, space life. Mark published several himself, including one on sewage, where he described how their wetland had transformed human waste into a vibrant ecosystem of aquatic plants, bugs, lizards, and one stowaway toad. Papers aside, Mark learned something in a very visceral way that can feel completely theoretical to most of us.
Mark: We are connected. Wherever you are, I don’t care if you’re in the middle of San Francisco or wherever, your air is being regenerated by the biosphere. Your water is being cleansed by vast biospheric cycles. So when I give talks, often I say, well, let’s make this real. Let’s just stop. The next breath that you take, try to visualize the green plants and the floating algae in the ocean that are producing the 20 percent of oxygen that’s in your air. And feel connected, feel thankful, feel appreciative.
Elah: The idea that we’re interconnected, that our actions profoundly affect our environment, these ideas can seem abstract, verging on meaningless. Until you’re sealed in a nearly closed system, hungry and losing oxygen. And by the way, it’s worth mentioning that Earth’s biosphere, aka Biosphere 1, is also a nearly closed system, just a much bigger one. Gravity ensures almost nothing goes out. And aside from a tiny bit of matter from the occasional meteorite, almost nothing comes in. This is it. We might not see the impacts of our actions as quickly or as clearly as they did in Biosphere 2, but they do have an impact. And as long as we’re on this planet, we’re going to feel it. Biosphere 2 is still standing today and open to visitors. It’s still a site of scientific research, but it’s no longer run by Mark’s crew, and it’s no longer airtight. So you can walk right in and breathe easy. If you want to learn more about life in Biosphere 2, you should check out Mark Nelson’s Pushing Our Limits and another book, Life Under Glass, written with two of his fellow biospherians.
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Our podcast is a co-production of Atlas Obscura and Stitcher Studios. The people who make our show include Dylan Thuras, Doug Baldinger, Chris Naka, Kameel Stanley, Johanna Mayer, Manolo Morales, Baudelaire, Amanda McGowan, Alexa Lim, Casey Holford, and Luz Fleming. Our theme music is by Sam Tindall.
