What Biosphere 2 can teach Elon Musk about failing on Mars.

Why NASA and Elon Musk don’t talk about Biosphere 2 when hyping Mars

Mars has captured human imagination for generations, promising a new frontier and a potential second home for our species. Yet the journey to colonise Mars entails more than rocket science and ambition—it demands a profound understanding of closed ecological systems, life‑support engineering and human psychology under extreme isolation.

The ill‑fated experiment of Biosphere 2 in Arizona offers a real‑world case study of how quickly meticulously planned habitats can unravel. By examining the technical and human challenges encountered by Biosphere 2, we can anticipate the risks for any Mars settlement and build resilient strategies to ensure survival on the Red Planet.

Genesis of a Mars prototype: From vision to reality

In the late 1980s, engineer John P Allen and philanthropist Ed Bass launched Biosphere 2, an airtight complex comprised of interconnected geodesic domes and pyramids. Covering 3.14 acres, it housed five terrestrial biomes rainforest, desert, savannah, mangrove and ocean plus an underground technosphere for life‑support machinery.

Its dual purpose was to emulate a Mars habitat prototype and to serve as a fully sealed “test‑tube” for Earth’s biosphere. This was humanity’s first large‑scale attempt to sustain humans entirely within an artificial environment, a precursor to what SpaceX envisions for Mars.

Atmospheric pitfalls: CO₂ spikes and O₂ depletion

Within days of sealing the initial crew, Biosphere 2’s atmosphere began diverging dangerously from Earth norms. Carbon dioxide (CO₂) levels climbed from around 380 ppm to over 800 ppm in just two days.

Soil bacteria, unchecked in the sealed system, respired massive quantities of CO₂, causing crew members to suffer headaches, fatigue and impaired cognition symptoms expected even on Mars if gas cycling malfunctions occur.

Simultaneously, reactions between excess CO₂ and calcium hydroxide in the concrete walls formed calcium carbonate, effectively scrubbing oxygen (O₂) from the air. By month 17, oxygen levels had fallen to 14.2 percent equivalent to conditions experienced at 17,000 feet altitude and the crew could barely ascend a flight of stairs without gasping. A Mars habitat that fails to balance CO₂ and O₂ could leave colonists facing chronic hypoxia and cognitive decline, undermining mission safety.

Engineering redundancy: Lessons for Mars life‑support

Biosphere 2 employed a complex network of air handlers, “lungs” variable‑volume geodesic domes that regulated pressure and external generators for temperature control. Despite an eventual budget of US$200 million (approximately US$363 million in today’s terms), the system required clandestine oxygen injections and secret deliveries of CO₂ scrubbers to keep the crew alive.

SpaceX plans to harness in‑situ resource utilisation on Mars converting CO₂ from the thin Martian atmosphere into methane fuel and breathable oxygen via the Sabatier reaction. However, until these processes are proven over long durations in Mars‑analogue environments, a single system failure could force emergency deliveries from Earth, defeating the purpose of self‑sufficiency. Any Mars life‑support architecture must be designed with multiple redundant loops, fail‑safe scrubbers and the capacity for on‑site repairs.

Agriculture under pressure: From crop failures to hunger

The Biosphere 2 crew believed their enclosed farm would reliably yield vegetables, grains, meat, eggs, milk and aquaculture fish. Instead, invasive species such as morning‑glory vines throttled crops, while nutrient imbalances in water systems led to algae overgrowth and toxic water.

Despite experimental claims of record agricultural productivity, the crew endured perpetual hunger, resorting to seed banks by their 14th month. Mars settlers will confront even harsher conditions: reduced sunlight due to dust storms, chronic radiation that degrades polycarbonate greenhouse panels and regolith laden with toxic perchlorates.

To avoid repeated agricultural failure, Mars habitats will require tightly controlled hydroponic systems, advanced LED lighting, nutrient monitoring at molecular precision and rapid detection and elimination of pests.