A biodome is a large, enclosed structure designed to replicate natural ecosystems under controlled conditions. Think of it as a self-contained slice of nature, sealed under glass or transparent panels, where temperature, humidity, and even atmospheric composition can be managed to support plants, animals, and sometimes people. Biodomes range from public attractions housing tropical rainforests in cold climates to serious scientific facilities testing whether humans could survive in sealed environments on the Moon or Mars.
How a Biodome Works
The core idea behind a biodome is borrowed from nature itself: create a closed loop where waste from one organism becomes a resource for another. Plants absorb carbon dioxide and release oxygen. Microorganisms in soil and water systems break down waste and recycle nutrients. Water evaporates, condenses, and returns to the system. In a well-designed biodome, only energy from the sun (or artificial lighting) needs to come from outside. Everything else circulates internally.
In practice, most biodomes aren’t perfectly sealed. They rely on mechanical systems to help with climate control, air circulation, and water filtration. NASA research into bioregenerative life support describes two general approaches: purely biological systems that use plants and microbial bioreactors to handle air and water recycling, and hybrid systems that combine biology with engineered hardware. Both can recycle water, scrub carbon dioxide, produce oxygen, and recover essential elements from waste. The challenge is keeping all of these cycles stable over long periods, especially when humans are living inside and consuming resources.
Biosphere 2: The Most Ambitious Experiment
The most famous biodome ever built is Biosphere 2, a 3.14-acre glass structure in Oracle, Arizona. Construction began in 1986 with the goal of researching self-sustaining technology for space colonization. Between 1991 and 1994, two crews of “Biospherians” were sealed inside the enclosure for extended missions to test whether a small group of people could survive in a closed ecosystem.
The results were humbling. Oxygen levels dropped unexpectedly as microbes in the soil consumed more than anticipated, and carbon dioxide fluctuated in ways the designers hadn’t predicted. Food production fell short. The missions revealed just how difficult it is to balance the countless biological and chemical processes that Earth manages effortlessly at a planetary scale. But the project was far from a failure. It generated valuable ecological data and demonstrated in concrete terms what works and what breaks down in a sealed living system. Biosphere 2 is now a research facility operated by the University of Arizona, and it continues to host experiments, including a sealed habitat called SAM (Space Analog for the Moon and Mars) that mimics conditions astronauts would face on other worlds.
Biodomes You Can Visit
Several biodomes around the world serve as public educational attractions, letting visitors walk through ecosystems they’d otherwise need to cross oceans to experience.
The Montreal Biodôme, housed in a former Olympic velodrome, recreates five distinct ecosystems of the Americas under one roof: a tropical rainforest, the Gulf of St. Lawrence marine environment, the Laurentian maple forest, the sub-Arctic Labrador coast, and the sub-Antarctic islands. Each zone maintains its own temperature, lighting, and humidity to match the real environment it represents, so you can walk from a warm, humid jungle into a near-freezing polar landscape in a matter of minutes.
The Eden Project in Cornwall, England, takes a different approach. Built inside a reclaimed clay quarry, it features two massive biomes constructed from interconnected geodesic domes. The Rainforest Biome houses over 1,000 plant varieties from tropical islands, Southeast Asia, West Africa, and South America. The Mediterranean Biome recreates the warm, dry climates of southern Europe, California, South Africa, and Western Australia. The structures themselves are engineering marvels, using inflated panels of a lightweight transparent material that lets in UV light while insulating the interior.
Why Biodomes Matter for Space Exploration
Every crewed mission to the Moon or Mars will eventually need to grow food, generate oxygen, and recycle water on-site. Shipping supplies from Earth is prohibitively expensive at interplanetary distances, so the principles behind biodomes become essential. NASA is actively funding university teams to develop exactly this kind of technology.
At the University of Arizona, researchers use Biosphere 2’s SAM habitat to test carbon dioxide scrubbers in a sealed environment that mimics Mars as closely as possible (without the reduced gravity or temperatures reaching negative 100 degrees Celsius). They run experiments both with and without the scrubbing systems active to understand how CO₂ accumulates when humans are present. At the University of Maryland, a separate team is working on inflatable space habitats, refining the interior layout for floor elements, air ducting, lighting, and equipment placement. Colorado School of Mines students are prototyping external shielding structures sized for inflatable lunar habitats, designed to be built using materials found on-site rather than hauled from Earth.
The thread connecting all of this work runs straight back to biodome principles: create a livable environment where resources cycle efficiently, biological systems handle as much of the life support as possible, and the whole thing stays stable long enough to keep people alive. What Biosphere 2 attempted in the Arizona desert in 1991 is essentially a first draft of what a Mars colony would need to get right.
Biodomes vs. Greenhouses vs. Terrariums
The terms get used loosely, so it helps to know the distinctions. A greenhouse is an open system. It traps heat and protects plants from weather, but air, water, and nutrients flow freely in and out. A terrarium is a small, sealed container that demonstrates closed-loop ecology at a tabletop scale, but it doesn’t support complex animal life or human habitation.
A biodome sits at the far end of that spectrum. It’s large enough to contain multiple interacting species, often including animals, insects, fish, and microorganisms alongside plants. It aims to replicate not just growing conditions but entire ecosystems, complete with nutrient cycling, predator-prey relationships, and atmospheric regulation. The most advanced biodomes approach what scientists call a closed ecological system, where material is recycled completely and only energy enters from outside. That’s the theoretical ideal. In reality, even the best biodomes need occasional inputs or corrections, but the goal of total self-sufficiency is what sets them apart from simpler enclosed growing spaces.