Could We Grow Space Stations? DARPA Investigates Bio-Mechanically Growing Massive Structures in Space

Insider Brief

• DARPA is exploring the feasibility of growing large bio-mechanical structures in space to reduce the need for launching heavy materials from Earth.
• The agency seeks input on developing bio-mechanical systems for applications such as space elevator tethers, orbital debris nets, and expandable space station components.
• A hybrid workshop in April 2025 will evaluate responses, with researchers invited to propose methods for ensuring structural rigidity, directing growth, and optimizing material efficiency.

DARPA is investigating whether biological materials can be used to build massive space structures, a move that, in a sense,  could mean companies, who face the daunting costs of launching materials into space, could grow structures rather than launching them.

The agency is seeking input on how to develop bio-mechanical systems that could assemble tethers for space elevators, orbital debris nets, or even self-growing wings for space stations.

The Defense Advanced Research Projects Agency (DARPA) issued a request for information (RFI) on large bio-mechanical space structures, asking researchers to propose methods for growing rigid, self-assembled biological materials in microgravity. The initiative could enable the construction of massive structures — over 500 meters in length — without having to launch bulky materials from Earth.

Responses are due by March 27, 2025.

Overcoming Expensive, Limited-Capacity Payloads

Building large structures in space has traditionally required sending up pre-manufactured components that are assembled in orbit. This method is expensive and limited by the payload capacities of current rockets. DARPA’s proposal envisions an alternative: leveraging biological systems that can self-assemble and grow in space, reducing the need for heavy launches.

“Given recent advances in metabolic engineering for rapid growth, extremophiles with novel properties, biological self-assembly properties of tunable materials, and emergent mechanical design principles of biological systems, DARPA is interested in exploring the feasibility of ‘growing’ biological structures of unprecedented size in microgravity,” the agency stated in the RFI.

One of the most ambitious concepts in the RFI is a biologically manufactured tether for a space elevator. Such a tether would require extreme tensile strength and flexibility, two qualities found in certain biological materials like spider silk proteins and filamentous fungal networks. If successful, this approach could dramatically alter space transportation by creating a low-energy link between Earth and space.

Other possible applications include kilometer-scale radio telescope arrays that could be deployed in space without the need for traditional support structures. DARPA also noted that self-assembling biological materials could be used to create orbital debris nets to capture space junk, a growing threat to satellites and space missions.

Hybrid Mechanical-Biological Approach

Although it’s never stopped them before, DARPA realizes this won’t be easy.

The key technical challenge, according to DARPA, is achieving structural rigidity. Many biological materials, such as fungal mycelia or protein-based fibers, are flexible and require external reinforcement. The agency proposes a hybrid approach, combining mechanical and biological engineering to ensure the structures remain stable once grown.

“A relevant analogy is that of a tent,” DARPA stated in the request. “Given the structural material of the tent poles, biological growth mechanisms are envisioned to be the ‘cover’ of the tent.” The key is to co-engineer the mechanical and biological components so that the final structure maintains its intended shape and function.

The RFI also raises logistical concerns about how these biological structures would be supplied with the necessary feedstock — the raw material needed for growth. The leading edge of the structure must receive a continuous supply of nutrients or precursor materials. DARPA is asking for input on whether these structures should grow aerobically (requiring oxygen) or anaerobically (without oxygen), and what environmental controls would be necessary.

The agency is particularly interested in estimates of the mass ratio between traditional construction methods and biological approaches. Launching large structures is costly, so any system that can significantly reduce the amount of mass that must be sent from Earth would be a major advantage. DARPA has requested that responses include an assessment of how much biological material could be grown in space compared to the amount that needs to be initially launched.

To evaluate the feasibility of these concepts, DARPA is hosting a hybrid workshop in April 2025 in the San Francisco Bay Area. The event will include group discussions and individual presentations from researchers. The agency will use insights from the workshop to determine whether a formal research program is warranted.

While DARPA’s call for proposals is exploratory, the agency has a history of funding unconventional technologies that later become mainstream. If bio-mechanical space structures prove viable, they could reshape how humanity builds infrastructure in space, making projects like space elevators and vast orbital installations more practical.

The potential applications extend beyond defense. NASA and commercial space companies are increasingly interested in in-situ resource utilization—using local materials to build structures instead of launching them from Earth. DARPA’s effort aligns with this broader trend and could have implications for space commercialization, deep-space exploration, and even planetary colonization.

Researchers interested in submitting proposals have until March 27, 2025, to respond. Those selected for the workshop will present their findings and discuss technical challenges with DARPA officials and other participants.

More information is available in the RFI and at DARPA’s website.