EXPANDING INTO THE SOLAR SYSTEM

Trying to cram a kilometre-sized structure into a metre-wide rocket is no easy feat

In December 1972, Apollo 17 flew to the Moon, marking the last time humans ventured beyond the bounds of low-Earth orbit. At least, for now. In August, Artemis was being readied for its first uncrewed test launch ahead of a future lunar landing. Over the coming decade, NASA will lead a team of global partners to build the Lunar Gateway, a space station that will act as a waystation to the Moon’s surface and perhaps even on to Mars. The Gateway – like the ISS and China’s Tiangong Space Station before it – is being built piece-by-piece from what can fit in a rocket.

But for interplanetary flight, you need bigger ships. The lack of gravity over a long-term trip through space causes muscle atrophy, heart problems, bone loss, eyesight degradation and immunosuppression. The solution is to build spacecraft that spin to simulate gravity (think 2001: A Space Odyssey). The trouble is, to spin astronauts around without making them sick you need a craft with arms that are up to one kilometre in length. That would take dozens of costly, tricky traditional launches to build. But a NIAC concept from Dr Zac Manchester of Carnegie Mellon University could potentially do it in just one launch.

“Our goal is to make a structure that can fit inside a single rocket fairing – which limits us to just a few metres across – and can expand out to a kilometre long in orbit,” says Manchester. “It turns out structures that only need to work in space don’t have to be very stiff or strong because the forces acting on them are very weak. In our case, the large structures we’re designing would launch folded up, so they would only need to withstand large forces in their folded configuration.”

He has been investigating structures made from interconnected sets of scissor linkages to create complex shaped structures that expand up to 1›0 times their original size. Such structures require thousands of moving parts, which is something normally seen as foolhardy in spacecraft, given you can’t just send out a mechanic if something gets stuck.

“This is one of the most difficult challenges in the project, and we worry a lot about mechanisms jamming during deployment,” says Manchester. One of the key parts of his current work on the project is perfecting the design to minimise the risk from any manufacturing errors. “We’re thinking about ways to strategically engineer compliance [the opposite of stiffness] into the structure to mitigate the risk of jamming.”

Jack-in-the-box spacecraft could soon be popping up across low-Earth orbit, ready to sail on to other planets.