* Biosphere 2 was a highly ambitious experiment to simulate a self-sustaining Mars colony in the Arizona desert.
* The 3.14-acre, bubble-like facility cost $250 million to build and operate.
* Eight men and women locked themselves inside for 2 years and experienced one incredible challenge after another.
* Though the experiment is often described as a failure, Biosphere 2's participants disagree. They say it generated science that has only grown in value as NASA and Elon Musk, the founder of SpaceX, push to populate Mars.
* A new 115-minute independent documentary called "Spaceship Earth" chronicles the Biosphere 2 experiment.
* Visit Business Insider's homepage for more stories.
A decade before Elon Musk founded SpaceX or spoke publicly about colonizing Mars, a different billionaire captivated the world with Biosphere 2.
Ed Bass, an oil tycoon, spent about $250 million to build and operate the facility as a proof-of-concept for a permanent, self-sustaining habitat on Mars. Four men and four women sealed themselves inside the airtight space in September 1991 and emerged two years later.
What followed was a spectacular and controversial story of human endurance, which is chronicled in a new documentary called "Spaceship Earth." The film debuts Friday on a handful of independent streaming sites.
Built into a hillside of the Arizona desert during the early 1990s, the 3.14-acre Biosphere 2 complex remains a functional marvel of engineering. Business Insider visited the facility in April 2018 to investigate the many challenges that early Martian colonists could face.
Here's what the high-tech complex of bubble buildings looks like today.
SEE ALSO: Elon Musk says he will colonize Mars — but a 25-year-old experiment in the Arizona desert reveals disturbing challenges that lie ahead
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Biosphere 2 is nestled in the foothills of the Santa Catalina Mountains in Oracle, Arizona. The area is part of the Sonoran Desert — an arid, unforgiving, and eerily Mars-like region that stretches from western Mexico into the US Southwest.
Source: Biosphere 2, Business Insider
A roughly 80-foot-tall glass pyramid poking out of the hillside greets visitors.
Source: Biogeosciences, Business Insider
Farther west in the sprawling 40-acre campus are other futuristic structures.
Source: "The Human Experiment," Business Insider
The architect Peter Pearce created Biosphere 2's space-age frame out of 77,000 steel struts and 6,600 silicon-lined glass panes to trap air inside. It can even withstand orange-size hail, which pummels Arizona about once every century.
Source: "The Human Experiment," Business Insider
The first crew of Biosphere 2 walked through a modified submarine bulkhead on September 26, 1991, and sealed the airlock behind them. They wouldn't leave as a group for two years. That entryway is where tours begin today.
Source: Business Insider
Business Insider's tour guide was John Adams, the facility's deputy director. Adams has worked there since the mid-1990s and is an expert on Biosphere 2's complex systems, science, and history.
"It really showed us how little we truly understand Earth systems and how infinitely complex they are," Adams said of the first Biosphere 2 experiment. "There were a lot of people who said, 'You bottle this up, you close it up, it's just going to turn into a big ball of slime.'"
It didn't, and the eight crew members emerged alive — though they wound up needing some outside assistance.
Source: Business Insider
When the first crew of "biospherians" settled inside the complex, it trapped 7.2 million cubic feet of air. All of its leaks added up to the equivalent of a thumb-size hole.
Source: "The Human Experiment," Biosphere 2, Business Insider
Though the facility was once a privately funded experiment in human survival, the University of Arizona bought it in 2011. It's now a scientific research facility, conference center, and tourist attraction.
Source: Biosphere 2, Business Insider
Biosphere 2 has seen about 3 million tourists and 500,000 students since 1991. The site also contains a village where visiting researchers can stay. It's quiet out there in the desert, save for the wailing of coyotes at dusk.
Source: Business Insider
Inside Biosphere 2, five "wilderness" zones — rainforest, ocean, savanna, marsh, and desert — emulated Earth's ecosystems. They helped scrub carbon dioxide from the air and generated oxygen. The crew lived in a connected habitat and farmed crops in an agriculture zone that's now called the hill slope.
Source: Business Insider
In that intensive agriculture zone, shown here in 1993, crew members spent most of their 12-hour days toiling in the fields and animal pens to harvest enough calories.
Source: "The Human Experiment," Business Insider
The kitchen was hallowed ground. Biospherians ate only what they could grow — mostly sweet potatoes and beans. It took four months to harvest enough ingredients to cook a pizza. Animals had to be raised and slaughtered to get meat. Coffee was a twice-monthly luxury.
Source: "The Human Experiment," Business Insider
Biospherians kept detailed records of seeds, plants, food, and animals. About 20% of species inside — mostly insects that were out-competed by cockroaches and crazy ants — went extinct during the first two-year experiment. Today, a small fraction of the original species survives.
Source: "The Human Experiment," Business Insider
Crops no longer grow in the agriculture zone. Instead, the University of Arizona gutted and renovated it into a multimillion-dollar experiment called the Landscape Evolution Observatory (LEO).
Source: Biosphere 2, Business Insider
LEO uses 90-foot-long bins of crushed volcanic rock to study how microbes transform inhospitable grit into environments where plants can take root.
Source: Biosphere 2, Business Insider
The goal is to understand how climate change will transform formerly arid regions as they're doused with rain from new weather patterns. Hundreds of sensors and sampling tubes embedded in the bins give scientists a 3D view of the evolving soil. The work may one day come in handy for Martian farmers.
Source: Biosphere 2, Business Insider
The most iconic areas of Biosphere 2, however, are its wilderness biomes. The air still smells of wet soil and plants, and though it's no longer sealed, it is noticeably more humid in here.
Source: Business Insider
The "ocean" holds about 660,000 gallons of saltwater and undulates with the help of a large wave generator.
Source: Business Insider
The ocean, one of the largest contained saltwater research facilities in the world, is being renovated to study coral bleaching, a scary consequence of climate change.
Source: Biosphere 2, Business Insider (1, 2)
Next to the ocean — through a sealed door on a cliff — is the rainforest biome.
Source: Business Insider
It's a thick, steamy jungle choked with tropical vines and trees.
Visitors aren't typically allowed into the rainforest area beyond a viewing point, but Adams escorted us around.
Biospherians treasured the bananas it grew for them. The sweet fruit was so versatile and prized in meal-making — and snacking — that it had to be locked in a room while it ripened (so no one stole it).
Source: Business Insider
Many of the crew members sought out the rainforest's diverse ecosystems and soothing waterfalls for an escape. Today, it's an active research facility used to study tropical drought due to climate change, as well as the cornucopia of compounds emitted by plants.
Source: Biosphere 2, Business Insider
After a trek through the rainforest, Adams walked us through the savanna, which connects the ocean, rainforest, marsh, and desert biomes.
Source: Business Insider
Plants of all shapes and sizes fill the savanna. During the first experiment, it also harbored a troop of four galagos, or nocturnal bush babies, that served as primate companions to the biospherians.
The desert biome at the end of the savanna encapsulates the environment that's right outside.
Source: Business Insider
Biospherians spent a lot of time weeding the region, since winter condensation on the roof dripped into the soil, growing plants that should have been dormant.
Source: "The Human Experiment," Business Insider
The complex's steel struts not only support the facility's glass panes, Adams explained, but also serve as a way to scale the walls for harvesting, measurement, cleaning, repairs and more. For fun, some biospherians even climbed to the ceiling and dove into Biosphere 2's ocean.
Source: Business Insider
Today, a few biospherian living quarters are roped-off museum exhibits showcasing some belongings of the crew members of second mission's crew. (Because of financial and legal issues, it lasted only seven months, in 1994.)
Source: Business Insider
In their spare time, some biospherians created art.
Source: Business Insider
A small science museum set up in Biosphere 2's former control room shows off a prototype for establishing a self-sustaining base on the moon or Mars.
Source: Business Insider
That concept, called the Prototype Lunar Greenhouse, consists of sealed tubes intended to supply 100% of the oxygen and 50% of the food a person needs in space.
Source: Business Insider
The tubes are designed to pop out and assemble within 10 minutes.
Source: Business Insider
A central module could deploy a dozen greenhouse tubes to keep a small crew alive for two years. This technology would, in theory, buy crucial time for astronauts to establish a permanent settlement on the moon or Mars. But NASA's funding for the project recently ran dry.
Source: Business Insider
Around the corner from the museum is a staircase leading to the habitat's towering library.
Source: Business Insider
The library offered biospherians a refuge from the cameras of a never-ending stream of tourists and press. This area, which still has the original and distinctive purple carpeting, is now off-limits to visitors.
Source: Business Insider
It's a beautiful space with a skylit dome ...
Source: Business Insider
... and a glass floor.
Source: Business Insider
Underneath Biosphere 2 is secret underworld of vital human machinery: the Technosphere.
Source: Business Insider
The Technosphere is a maze of pipes, tubes, conduits, pumps, sprinklers, transformers, air handlers, and other parts required to keep air, water, and electricity flowing through the complex.
Source: Business Insider
As biospherians would discover, concrete that lined the facility's base was soaking up carbon dioxide. Soil microbes were gobbling up oxygen, turning it into carbon dioxide, and trapping it in the concrete — away from plants that could turn it back into oxygen.
Source: "The Human Experiment," New York Times, Business Insider
This led oxygen levels to drop to the equivalent of the peak of a 15,000-foot mountain. To fix the problem, biospherians tried to collect every scrap of organic matter, dry it out in the Technosphere, and halt its decay.
Source: "The Human Experiment," Business Insider
But the design flaw proved too great. Mission managers eventually injected 14 metric tons of liquid oxygen into Biosphere 2 to make up for the chemically trapped gas.
Source: "The Human Experiment," Business Insider
That procedure was performed in one of two domed buildings called "lungs," which helped balance Biosphere 2's air pressure and prevent leaks. Without them, air that warmed during the day would have expanded and blown out panes of glass, ruining the experiment.
Source: Business Insider
The lungs are remarkable feats of engineering. A giant weight suspended on an airtight membrane moves up as the facility's air warms and expands during the day, and drops when it cools and contracts at night. And if there is a small leak, the weight pushes air out (rather than sucks it in). A fan above the weight helps it move up and down.
"The membranes rose or fell simply in response to the state of expansion or contraction of the whole volume of air within Biosphere 2," Mark Nelson, who conceived of and made the overall design for the lungs, told Business Insider in an email. "Typically, that would be around 20 feet of vertical movement by both lungs every day."
To show how the lungs work, Adams opened a nearby airlock. The lung's weight immediately descended, forcing a blast of air through the unsealed door.
Source: "The Human Experiment," Business Insider
With my tour complete, I exited through the gift shop. On display was a book by Jane Poynter, one of the original crew members.
The book is one of the most detailed and candid accounts of Biosphere 2's genesis, construction, goals, and problems.
It's also an insider's account of a plethora of human and scientific controversies that haunt the project's reputation to this day — including a remarkable story involving sabotage, federal agents, and Steve Bannon, the former White House chief strategist.
Source: Business Insider
Poynter eventually married Taber MacCallum, a fellow biospherian. "It was an incredibly audacious and, in so many ways, incredibly successful attempt at building a prototype space base," Poynter said of Biosphere 2.
Together, the couple started a high-altitude-balloon company called World View.
Source: Business Insider
Some scientists today view the experiment with skepticism and describe its founding staff as "cultish," a description Poynter vehemently rejects. Barring a few design flaws, she said, Biosphere 2 showed that people could survive for years without much — if any — outside help.
Source: Business Insider
Getting to Mars is the easy part — the success or failure of a colony will depend on its resiliency and life-support systems. Elon Musk is targeting a first SpaceX crewed mission later in the 2020s, but it remains to be seen how anyone would survive long-term.
"First we need to understand Earth's systems — we need to understand how we're going thrive here on Earth," Adams said. "We have not figured this out yet."
Sources: Business Insider (1, 2, 3)
This story was originally published on May 1, 2018. It has been updated with new information.
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