Imagine these scenarios: multiple commercial space stations orbiting the Earth. Long-term infrastructure on the surface of the moon. A space station orbiting the moon and acting as a launch point for missions to Mars. Vast solar arrays in GEO, gathering power from the sun and beaming it to the Earth’s surface.
All of these projects are underway, and all of them hinge on the same capability: on-orbit construction of large infrastructure.
The space industry is poised to grow significantly over the next several decades. But how that growth progresses could depend largely on how and where infrastructure is built.
“Most economies are underpinned by infrastructure,” said Lee Rosen, CEO and founder of ThinkOrbital, a space industry construction startup that has demonstrated electron-beam welding for robotic assembly.
Building infrastructure in space could precipitate the next big step forward in space technology and be a key part of building a resilient space economy. “It will materially change the way that space works, in a very good way,” said Sam Adlen, co-CEO of Space Solar, a U.K. startup working to build massive solar arrays in orbit.
Are Large Space Structures the Future of Space?
Building solid and dependable infrastructure on orbit could have significant business returns. On a short time scale, the construction of very large satellite structures increases the performance ability of the satellites, translating to immediate business growth.
On a longer time scale, good infrastructure in orbit will create better sustainability, more efficient use of resources and longer technology life spans.
“If you are able to manufacture large structures, you are also able to repair,” said Advenit Makaya, an Advanced Manufacturing Engineer at the European Space Agency (ESA). “The processes to manufacture and to repair something are pretty much the same. And if you are repairing on orbit, you extend the life of satellites and you don’t need to send new ones so frequently.”
Expanding the size of existing structures and spacecraft will be the first step in expanding our in-space capabilities. “By large space structures, we start out with making satellite parts bigger than what they are at the moment,” Makaya said. “Bigger antennas mean more data throughput, more returns for telecom operators, bigger telescopes and bigger science returns for the missions.”
Looking further into the future, we can anticipate the construction of massive structures: data centers, solar panels, habitats and space stations. They key will be designing construction processes that can build complex structures in space, from antennas to commercial space stations.
But before you can start building, you first have to get all of that material into space.
Launch: The First Major Hurdle
Luckily, the launch bottleneck is widening, and the space industry is putting more and more mass into orbit, as demonstrated by the thousands of satellites launched into LEO each year.
“Right now, launch is reliable, it’s affordable, it’s super high-cadence—it’s everything we’ve always wanted,” Rosen said. “The next big constraint that we really have to overcome is the size of things in outer space, because everything in space is tiny compared to any terrestrial application.”
The problem? “Everything we’re sending to space needs to fit within a rocket and survive launch and acceleration,” said Gilles Bailet, a lecturer on space technologies at the University of Glasgow. Finding a way to work within these limitations will be key to building better, long-lasting and sustainable infrastructure in orbit. For some, that means stacking as much ready-to-build material as possible into a rocket payload. For others, it means packing copper polymer into a rocket and then 3D printing materials in space as needed. But no matter how you approach the problem, some assembly will be required.
Engineers must also consider “the difficulty of handling a very large structure,” Makaya added, as large structures are more susceptible to passing debris, and are harder to manage control and movements. For example, satellite Attitude and Control Systems (AOCS) are the complex processes used to control the orientation and movements of a spacecraft.
For a large structure, this difficulty is multiplied out onto a much larger scale—potentially on the scale of kilometers. Larger structures must be able to regulate their movements, hold their shape, deal with extremes in temperature that can cause shrinking and expansion and handle radiation.
“They have to resist the space environment in terms of temperature variation, in terms of radiation, in terms of vacuum,” Makaya said.
3D Printing: Building What You Need Where You Need It
3D printing is a favored process for construction in space because it allows for flexibility in terms of shapes and sizes that can be produced, and it requires relatively little equipment. The ESA, for example, 3D-printed LEGO-style blocks using dust from a meteorite last year, then sent the first metal 3D printer to space.
“You want to minimize as much as possible the type of equipment you bring into space,” Makaya said. Theoretically, with a 3D printer, you can cut, join and bolt, all with a single process. It also works with a variety of different materials and opens up the possibility of in-situ resource utilization on the moon and Mars. “You can use lunar regolith, the dust you find on the surface of the moon, to print structures,” Makaya said.
Earlier this year, Bailet led a team of researchers at the University of Glasgow in a demonstration of 3D printing in microgravity. To simulate the space environment, they collaborated with Novaspace to send a 3D printer on a parabolic flight, which experiences twenty seconds of microgravity at the apex of the flight. Following the successful demonstration, the team is moving on to more ambitious technologies: 3D printing a large antenna in space and using it to communicate back to Earth.
Even with the proper materials are in place, the battle isn't over. As Bailet said about the next major obstacle, “Once you build different modules, how do you assemble them?”
Robotic Assembly: Putting the Pieces Together
Once materials are in place, robots must be able to perform the actual assembly process. Human presence in the construction processes would be expensive and risky, and nearly autonomous robotic construction is already a proven technology for many terrestrial applications.
Space Solar has a simple but effective vision for the construction process: “You want to construct in as simple of a way as possible,” Adlen said. “You want lots and lots of the same module. It can be hundreds or thousands of the same module built together.”
Space Solar recently demonstrated its AlbaTRUSS technology, which showed “the ability for a transporter system to build a carbon truss structure that aligns with the assembly concept for our solar power satellites,” Adlen said. Following construction, assembly robots would then live on the structure, continually upgrading and maintaining it.
ThinkOrbital has a similar vision. “If you take a soccer ball made up of pentagons and hexagons and were to deflate it, unstitch it all and stack it flat, you could obviously get a lot of material in a very small volume,” Rosen said. That solves the problem of getting material onto a rocket and into orbit. Once there, “you could then use precision robotics and welding technology to mechanically assemble it in order to make an airtight and rigid structure in outer space.”
Looking Forward: Infrastructure Creates Sustainability
In-space construction processes and the infrastructure that results could dramatically change the space industry and the activities that are possible to perform in space.
“Power is the next bottleneck in space,” Adlen said. That’s why Space Solar is working to put large solar arrays into space, he said—because having a power source already sitting in orbit would be a game changer for many industry players. Once these large solar arrays are in place, other infrastructure can cluster around them, including data centers, next generation communication satellites and even space habitats. Ideally, this would also provide the infrastructure necessary to make space activities a sustainable economic endeavor.
Satellites within a constellation would function as normal, with periodic repairs performed by robots. When a mission is finished, instead of deorbiting a satellite, the antenna could simply be recycled and rebuilt for a new mission that may have different technical requirements.
“If you’re able to have a really sturdy and highly efficient in-space manufacturing capability, you can eliminate about 70% of the need for rocket launches,” Bailet said. “It’s actually feasible to have a locally circular economy among a constellation.”
Once construction technology has been proven and enough material has been launched into orbit, the economy of space activities could become much more sustainable. Materials like copper, polymer and aluminum could be recycled and re-printed into new structures, while launches from the surface of the Earth would be reserved for more valuable materials—like an advanced telescope, or a human being.
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