When rockets can no longer hold oversize payloads, building in space might be the best way to go.
A rocket blasts off from the launchpad, carrying a couple dozen tons of cargo into space. In the span of a few minutes, the rocket accelerates to around 17,500 miles per hour, orbiting the Earth at nearly 300 miles above the surface.
What is this rocket carrying? Perhaps a communications satellite, a NASA spacecraft, or some payload for the military? Actually, the rocket isn’t even carrying a spacecraft at all. Instead, its payload contains several tons of high-grade plastic and pre-fabricated components, material that will be fed to a 3D printer waiting in orbit. This futuristic printer will then use the plastic and components to construct a functional satellite spanning several miles.
A mile-wide satellite might sound impossible, but that’s exactly where the space industry is headed. In the future, giant telescopes, communication satellites, solar arrays, and space stations will fill the space around the Earth, and many of them will be several times larger than anything ever built on the surface.
Headquartered in Mountain View, California, Made In Space is working to make that dream a reality. For the past few years, they’ve operated the Additive Manufacturing Facility, one of the only 3D printers in space. While the AMF sits comfortably aboard the International Space Station, Made In Space has plans to launch a new printer that would operate exclusively in the vacuum of space.
Their prototype, called Archinaut, is scheduled to launch later this year. [Update: Made In Space says the Archinaut is currently scheduled to launch in 2019.] Future machines like Archinaut will be able to print nearly everything in orbit—where there’s no limit on size.
“We can manufacture a structure that couldn’t support its own mass if it were on Earth,” says Made In Space President and CEO Andrew Rush. “The only practical limitation you have is how much material you’re providing to the system.”
The first Archinaut prototype is mostly just a proof-of-concept and won’t be constructing mile-wide satellites anytime soon. “First you crawl, then you walk, then you run,” says Rush. “We’ll start out with manufacturing space-optimized trusses and booms and reflectors to provide a supply capability that we can’t currently achieve.” But once this tech gets off the ground, it can be used to build structures as big as their owners want them.
There are plenty of technical challenges to overcome, too, says Rudranarayan Mukherjee, a robotics expert at NASA’s Jet Propulsion Laboratory. “Autonomy, manipulation, perception, force control, metrology” are all areas where our robots need to improve. A robot needs to see what it’s doing and delicately piece together components with little or no human oversight.
Satellites and other space structures also have to be completely redesigned, says Mukherjee. “When you talk about making things in space, you have to have interfaces that are standardized and tested for that environment, that provide structural aspects, communication, power lines have to be redesigned, as well as thermal aspects.”
Spacecraft parts have to come together like Lego, fitting in all sorts of combinations while simultaneously providing electrical and data connections.
This is the heart of what Rush is trying to do. He believes that in a few decades, space-based manufacturing is going to be “fundamentally transformative.”
Once these technologies make it possible to construct extremely large structures in space, plenty of people will want to build them. Rush mentions “reflectors that are larger than the International Space Station,” as well as “very long antennas,” as practical structures that are widely useful and easy to build.
Better Eyes in Space
But what really excites Rush is the potential to build truly massive space telescopes. “Our scientific community is going to need 15- or 30- or even 100-meter telescopes” in the near future, he says.
Nick Siegler, chief technologist at JPL, agrees that in-space assembly will likely become a requirement. “As we want bigger and bigger telescopes, at some point we are going to exceed the size of the fairing on the rocket,” he says. “When that happens, we will have no choice but to assemble it in space. In-space assembly for large telescopes is a matter of when, not if.”
But when exactly is still an open question. “It could be next decade, or it could be two, three, or four decades in the future,” says Siegler.
As rockets get bigger, like SpaceX’s Falcon Heavy or its future BFR, so do the sizes of their payload fairings. Bigger fairings mean larger telescopes can be launched from the ground without having to resort to in-space assembly.
“[Falcon Heavy] had a pretty large fairing,” says Siegler. “It’s about 5 meters in size, so that enables future telescopes to be deployed autonomously up to about 9 meters. You can do a lot of pretty exceptional science with 9 meters.”
When scientists need a telescope bigger even than that, they could turn to NASA’s upcoming Space Launch System. The fairing on that rocket will allow for 12-meter telescopes, and a planned upgrade in the late 2020s or early 2030s would bring that limit up to 15 meters. That’s larger than any optical telescope ever made, beating the current record holder by nearly 5 meters.
But someday even a 15-meter telescope is going to be too small, and the only option at that point would be to build a giant telescope in space. Even before reaching that threshold, it could be cheaper to start assembling our telescopes in space sooner than later, and if you decide to build in orbit, you might as well go big. With enough material—and enough funding—those 30- and 100-meter telescopes could be built within our lifetimes.
What Comes Next
The possibilities for in-space assembly and manufacturing are nearly unlimited. This is a true “if you can dream it, you can do it” type of scenario. But the technology is still very much in its infancy, with the first prototype device still stuck on the ground.
But in a sense, we already know what the impact is going to be because we’ve done it before. The first large in-space assembly project began twenty years ago with the construction of the International Space Station. The ISS is the largest structure ever built in space, and it was done without any fancy robots or 3D printers.
The impact of this single space-assembled structure has been enormous. The impact of any future space-assembled or space-built structure would be even more so.
No one knows for sure what the future of space exploration will look like, but there’s a very good chance it’ll be built there.