US military wants to grow giant biological structures in space

The US military is brainstorming ways to build large structures in space, from telescope antennas to elevator tethers. By growing these objects in microgravity using biological organisms, they hope to avoid the costly and painstaking process of launching components from Earth.

“We have yet to unlock the potential of biology for space production and manufacturing,” says Michael Nayak, program manager for the US Defense Advanced Research Projects Agency (DARPA). The combination of biology and mechanical engineering could unlock new ways to “manufacture at unprecedented sizes in space”, he says, but acknowledges that “the devil will be in the details”.

DARPA envisions growing “biomechanical structures” at least half a kilometre long, such as new modules for a commercial space station or long tethers for space elevators linking Earth’s surface and orbit. Other possibilities include huge nets for collecting orbital debris or even “kilometer-scale” antennas for radio astronomy telescopes, according to a notice posted 25 February on a US government website for federal contracts.

To be useful, these biological structures must be able to grow in the desired directions and integrate with electronics and other structural materials. “Making fully ‘grown’ large-scale structures is beyond the capabilities of today’s technology,” says Erika DeBenedictis at the Francis Crick Institute, a biomedical research centre in the UK. “That is the aspect where this program has the potential to move the needle and develop new technology.”

Directional growth on a large scale has so far only been demonstrated in multicellular organisms such as trees or underground networks of fungi, says Nils Averesch at the University of Florida. Some researchers have tried creating engineered living materials from unicellular organisms such as microbes, but they have yet to achieve precise control over their final formed shapes.

“Controlling this artificially – especially without gravity, which many life forms rely on to determine a direction – is still difficult,” says Averesch. “Even if directionality of growth could be controlled also in microgravity, the space environment is incompatible with biological activity.”

They would also probably need to launch “significant amounts” of material into space to feed the growing biological structures, which could outweigh the benefits of the approach, says Averesch.