The Complexity of Equilibrium

The Complexity of Equilibrium

In the 1960s, scientists asked questions such as: How could humans survive for a long time in space—or even form permanent settlements on other planets? What does it take to sustain life within a sealed environment, like a spaceship or underground bunker on Mars? How can we create an ecosystem in a closed environment, capable of reaching an equilibrium necessary to keep people alive?

For this purpose, Earth can be treated as approximately closed to matter, while energy flows through it. Many interacting processes sustain the conditions humans need. Beginning with experiments in which samples of microbial life were sealed permanently into flasks (some of which are still alive today),[10] researchers demonstrated ways in which closed systems could sustain themselves. Such experiments, on a modest scale, formed an important part of the Russian and US space programs. The project known as “Biosphere 2” (with planet Earth being Biosphere 1) attempted closure on a much larger scale.

The source describes Biosphere 2 as a 180,000-square-meter structure in the desert near Tucson, Arizona, with almost 204,000 cubic meters of glass in its aboveground structure and a steel framework reaching 27.7 meters.[11] Parts of the building are rectangular, parts are pyramid-shaped, parts are domed. Inside, Biosphere 2 contains the following five separate ecosystems mimicking key environments in the outside world:

1. Coastal fog desert
2. Tropical rainforest
3. Savanna grassland
4. Mangrove wetland
5. Ocean

Biosphere 2 also includes areas for agriculture, as well as underground areas for housing the equipment necessary to keep the whole thing functioning. It was the brainchild of John Allen and Ed Bass. Allen was a metallurgist and Harvard MBA who, following a psychedelic trip in the 1960s, founded a commune called Synergia Ranch in Santa Fe County, New Mexico.[12] Successful relative to similar projects at the time, Synergia attracted the attention of Ed Bass, a young billionaire heir to an oil fortune.[13] Together they launched several ambitious projects before deciding in 1984 to set out and discover what it would take to form a Mars colony that humans could live in. They assembled a team of experts to create Biosphere 2.

In 1991, the “Biospherians”—a team of eight individuals who’d spent years preparing—were sealed inside Biosphere 2 for two years. The aim was to maintain a functioning ecosystem without supplies of food, water or air from outside. Energy could still enter the system. They would farm all of their food, grow plants and raise animals, and strive to maintain all conditions necessary for their survival. By the time they emerged, the Biospherians had endured a great deal. Oxygen levels had sunk drastically, to the point where it proved necessary to bring in outside oxygen to keep them alive. They struggled to meet their caloric requirements while doing demanding physical work. The Biospherians frequently fell out with one another and with those controlling the experiment.

Biosphere 2 attracted criticism for failing to remain materially sealed. That raises a question about what it meant for the experiment to “succeed.” The closure fell short of its goal, but it also produced information for later experiments. Maintaining a viable habitat in Biosphere 2 required coordinating plants, animals, people, air and water. Running the system exposed interactions the planners had not fully anticipated.

Biosphere 2 showed how difficult it is to maintain life in a sealed habitat. Ecological feedback can stabilize some conditions while amplifying other changes. Designers must anticipate dependencies, monitor conditions and intervene when the system moves outside a viable range.

A system’s equilibrium is not necessarily a condition people want or can survive in. The Biospherians had to manage the habitat actively. They produced almost all their food, obtained clean water and kept hundreds of plant and animal species alive, even as other conditions deteriorated.

Planning Biosphere 2 showed how a change to one part of an ecosystem can affect many others. The animals chosen for Biosphere 2 had to be assessed for what they needed to survive and how they might alter the rest of the habitat. Linda Leigh, who helped develop Biosphere 2 and was one of the participants sealed inside, described the complexity of choosing animal species to include.[14] Every animal needed to be evaluated for how it might interact with everything else. For example, they consulted a bat specialist to choose a species that could pollinate some of the plants. Yet when they looked at the consequences of including that species, they were huge:

One of those bats would nightly have needed to eat twenty two-centimeter-long night-flying moths, and would have had to [have] encounters with over a hundred per night in order to catch the twenty. Where would all of the moths come from? What would their larvae eat, and could we have enough and the correct habitat for the moths’ eggs? In addition, the air handlers, as designed, would have sucked the moths in and killed them. Engineers suggested a fine screen over the opening to the fans in order to give the moths a chance to survive the pull. That screen would increase the electricity needed to pull the air through, a budget increase that was not supported.[15]

In another example, an expert tried to find a hummingbird species that could live inside Biosphere 2.[16] They had to ask lots of questions about each option, which a casual observer might not consider. What shape is this type of hummingbird’s bill? Will it be the right size to pollinate enough plants? What kind of mating display does this type of hummingbird exhibit? Will it be at risk of colliding with the glass during this display? Each answer introduced further design constraints.

Even the most seemingly inconsequential things had the potential to compound and endanger the lives of everything in the ecosystem. As professor and filmmaker Shawn Rosenheim explained, “Part of the point in building a self-sustaining world was to make the unimaginably rich interconnections of the actual Earth newly vivid.”[17] The initial two-year closure experiment was meant to be the first of fifty such experiments, with the aim of improving incrementally each time. The account reports better species survival than anticipated: 30 percent of the species inside went “extinct,” compared with a predicted loss of up to 70 percent.

At the time of writing, Biosphere 2 still stands, having been donated to the University of Arizona in 2011. From the outside, it looks like a shadow of its former self. The windows are murky without sufficient funds to employ a full-time crew to keep them clean, and rust accumulates on the structure. But inside, Biosphere 2 remains full of life. Many of the microcosms within it are thriving, having found the equilibrium they need to function as they would in the outside world. Researchers still utilize it as a unique place for valuable controlled experiments they can’t easily do anywhere else.