For decades, space engineers have imagined shipping steel, glass, and concrete to other worlds so that future explorers can build homes on Mars and even further from Earth.
A new study led by Robin Wordsworth at Harvard’s School of Engineering and Applied Sciences turns that idea on its head. Rather than launching heavy construction kits, the team shows that habitats can, quite literally, grow themselves.
“If you have a habitat that is composed of bioplastic, and it grows algae within it, that algae could produce more bioplastic,” Wordsworth said. “So you start to have a closed-loop system that can sustain itself and even grow through time.”
Turning algae into architecture
At the heart of the concept is Dunaliella tertiolecta, a type of hardy green algae already used on Earth for aquaculture and biofuel research.
The researchers conducted a series of lab tests where they 3-D printed dome-shaped chambers using polylactic acid (PLA), a common bioplastic fermented from plant sugars.
The walls were only a millimeter thick, but strong enough to hold liquid water even when the outside pressure fell to Mars-like levels of about 600 pascals – more than a hundred times lower than on Earth.
Inside these tiny “greenhouses,” the algae were bathed in carbon-dioxide-rich air, fed with artificial sunlight, and left to do what algae do best: photosynthesize, grow, and multiply.
After ten days, cell counts in low-pressure chambers nearly matched those in cultures grown at normal Earth pressure. This confirmed that life could flourish despite the thin atmosphere.
Light management was another hurdle. Mars receives plenty of visible sunlight, but its surface is bombarded by harmful ultraviolet rays.
Tests showed that a single millimeter of PLA blocks all UV-C radiation and much of UV-A and UV-B while still letting through the red and blue wavelengths that photosynthesis requires. In short, the plastic skin both protects and nourishes its green tenants.
Self-growing habitats on Mars
If the algae thrive, the cycle becomes self-amplifying. Researchers can convert extra biomass into fresh PLA, then print or mold it into new habitat walls.
A simple mass-balance analysis in the study suggests that with realistic conversion efficiencies, a foot-deep algae cultivation pond beneath each habitat could produce more than enough bioplastic to meet repair needs.
This includes material to address routine weathering. Surplus production could even allow the living area to double every couple of years.
In theory, a single lander packed with starter cultures, nutrients, and a modest 3-D printer might seed an entire settlement that grows like coral over time. Operating at low pressure, the domes place far less stress on their walls than habitats built for full Earth pressure.
The team calculated that a one-millimeter PLA shell can comfortably withstand the loads. Reinforcement could come from additional biological materials, such as bacterial cellulose aerogels, which also provide insulation and help maintain plant-friendly temperatures between 10-30 °C (50-86 °F).
Algae domes for deep space
Although the experiments targeted Mars, similar biomaterial bubbles could help researchers design life-support systems for the Moon, free-floating space stations, or even harsh environments on Earth.
Wordsworth notes that a later phase of the project will test whether the same strategy can function in a complete vacuum. This is essential for lunar use and will test whether the algae-PLA loop can run without outside resources after kickoff.
“The concept of biomaterial habitats is fundamentally interesting and can support humans living in space,” he said. The progress in off-world sustainability almost invariably “has spinoff benefits for sustainability technology here on Earth as well.”
One immediate benefit is the potential use of the domes as low-energy bioreactors. Unlike conventional indoor farms that rely on electric lamps, algae inside translucent shells harvest natural sunlight. That eliminates a major power drain – a critical advantage on distant worlds where every watt matters.
Surviving Mars’ extremes
Of course, challenges remain. Mars swings through dramatic temperature cycles, and liquid water will freeze solid without extra heating or insulation.
Perchlorate salts in Martian dust are toxic to many organisms, so engineers will need robust filtration or genetically tuned microbes.
Gas exchange will also need to be balanced. PLA walls allow carbon dioxide to seep in and oxygen to seep out, but water vapor escapes the same way, risking desiccation unless clever humidity controls are included.
Shielding human occupants from cosmic radiation also demands thicker or layered shells, perhaps combining PLA with locally mined regolith.
Finally, the team is keen to move from flask-scale proofs to pilot-scale structures that people can walk into. The future domes could pair the algae chambers with silica-aerogel skylights. This technology, developed by Wordsworth’s group, captures sunlight while trapping heat to create temperate oases on an otherwise frigid plain.
Bioplastic homes grown by algae
The broader message of the study is that biology can be both passenger and partner in humanity’s push beyond Earth.
If algae build walls and microbes recycle plastic, habitats could grow and repair themselves instead of being shipped from Earth. Instead, they become living, self-healing ecosystems.
That vision aligns with NASA’s growing interest in in-situ resource utilization and with wider efforts to craft sustainable, circular economies at home.
In other words, the green slime that clings to your fish tank might one day help roof the first Martian village – and teach us a few lessons about building lighter, cleaner, and smarter back on the pale blue dot.
The study is published in the journal Science Advances.
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