The First Extraterrestrial Human Habitat Has Already Been Built

Earth in “The Pale Blue Dot”, taken by Voyager 2 in 1990 at the direction of Carl Sagan.

The recent renaissance of space exploration has re-injected science fiction with fantasies of humans surviving against all odds in exotic, perilous environments. We imagine ourselves to be new-age frontiers people, wrangling with the overpowered forces of nature — and somehow winning. However, space is nothing like the Wild West of the 1800’s. Even the most extreme tundras of Siberia or pressures of the Mariana Trench are compatible with life on some fundamental level. After all, humans (or at least some predecessor to our species) were shaped by the terrestrial climate which often feels like our adversary.

Out there is different. Space is vast, majestic, and wild. That wildness somehow feels connected to its hostility. It knows nothing of our habits or habitats. Its perceived sterility makes it the ultimate challenge for our species. Can humans survive on an alien world? Can we create a habitat in the uninhabitable? The idea feels crazy. Short of destroying the planet and rebuilding it in our image, how could humans eke out a comfortable existence? Well actually, as with many things Sci-Fi and weird, we can look back a few decades for inspiration.

Introducing humanity’s first off-world habitat — on Earth

A project from the 80’s called Biosphere 2 aimed to answer these questions. Biosphere 2 attempted to recreate a balanced ecosystem within a completely sealed environment. It was an expansive complex, containing 7 different biome types populated by dozens of species. Its 3.14 acres promised to sustain eight humans with food, water and oxygen for up to two years. Biosphere 2 was named as a tribute to Biosphere 1 (also known as Earth), and its creators held ambitions to invent the best technology for future human space colonies. However, with grand ambitions came even grander challenges.

The first experiment for Biosphere 2 enclosed eight humans in the habitat for two years between 1991 and 1993. They quickly became experts in carbon management as they learned the consequences of building up CO2 in an enclosed environment. They carefully maintained the ecology of the biomes to sustain the fauna and flora of the biosphere. They farmed endlessly as they struggled to produce enough food for themselves, and they experienced the dizzying effects of gradually decreasing ambient oxygen. Eventually, they broke from the experiment to remedy some of these challenges, receiving an infusion of oxygen 16 months into the mission and relieving CO2 concentrations with a carbon scrubber. People outside the experiment saw these interventions as a betrayal of the experiment’s thesis — as a failure of Biosphere 2.

However, Biosphere 2 wasn’t all loss. The “biospherians” became sensitive to waste in their environment. They avoided products with lasting footprints because their waste would harm the balance of the biome and make their next meal harder to grow. The smallness of their enclosure amplified an effect that can be lost in our planet’s largeness: the Earth’s most distant ecosystems still affect each other.

Where do we go from here?

Since Biosphere 2, attempts at building a similarly ambitious closed habitat have been abandoned. A shorter 7-month experiment was run at Biosphere 2 starting almost as soon as the first experiment ended; however, it was cut short due to change in management and funding issues. Today, Biosphere 2 is a “semi-closed” ecosystem, opened to tours from the public and a flux of researchers.

A Mars iteration of Biosphere 2 would be difficult to pull off as the first human habitat on another planet. We don’t have the technology for rapidly building extraterrestrial megastructures. Furthermore, populating the biosphere with enough Earth species for several ecosystems might be even harder than constructing the habitat. Our first off-world human habitats will probably function more like resource-dense ant hills than total replicas of Earth ecosystems. However, NASA is quite concerned about the effect of such habitats on the long term mental health of Mars-bound astronauts. And while the ISS is itself an experiment in tight, isolated human habitats, its missions are nothing compared to the two or more years of isolation that the first crew to Mars would have to experience. A biosphere could be a necessary upgrade to give humans a sustained presence beyond Earth.

Biosphere 2 was a quest to make fiction into reality. Through Biosphere 2, we attempted to recreate Earth to suit our needs; however, along the way, we learned something precious. We learned how delicate and unique what we have on Earth really is.

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