Robot successfully builds space structure in first autonomous construction demo

The Novel Orbital and Moon Manufacturing, Materials and Mass-efficient Design (NOM4D) program has achieved the first ever demonstration of automated in-space assembly, according to DARPA. A California Institute of Technology (Caltech) payload operating in orbit built a truss structure from individual components using a relatively simple gantry robot able to move along three linear axes. The robot connected composite truss members using custom-designed joints while simultaneously deploying a thin reflective mesh, a proof-of-concept for future space-based antennas. The accomplishment validates a new approach for how future large-scale space systems may be designed, launched, and constructed.

"NOM4D's objective is to enable efficient, scalable construction of very large structures in space," said Andrew Detor, NOM4D program manager. "By 'very large,' I mean hundreds of meters or kilometers in scale. Nothing approaching that scale can be achieved today." To date, assembly for space structures is either done completely on earth, which sets a limit on how large a structure can be folded into a launch vehicle, or assembly is achieved by manually putting together large pieces sent up over a series of individual launches. In contrast, "you can think of the Caltech approach as similar to Tinkertoys or K'nex construction toys: individual truss members are joined at nodes, one section at a time, to create a larger structure," Detor said. "Within the automated assembly box, each section is built piece by piece, a reflective mesh is attached, and the assembled sections are deployed as they are complete. There are no complicated robotics or advanced algorithms; it's just solid engineering from the Caltech team to combine operations in a way that scales."

The robotic truss builder worked to construct a 1.4-meters-diameter reflector antenna without the help of astronauts, the New York Post reported. The robot was conceived, designed, and built by Caltech researchers and funded by the US Department of War's Defence Advanced Research Projects Agency (DARPA). The truss builder, part of DARPA's NOM4D program, consists of an autonomous manipulator that picks up struts and joints held in nearby dispensers to repeatedly assemble identical sections, or bays, of a perimeter truss. "This is the first time that a structure has been autonomously constructed in space," says Sergio Pellegrino, team leader of Caltech's Autonomous In-Space Tensioned Reflector Assembly (ASTRA) demonstration. ASTRA is a robotic builder that has spent the last six months in space, working to construct the reflector antenna from composite fibre tubes, aluminium joints, and a Kapton reflective surface.

The NOM4D Caltech payload was launched into orbit aboard SpaceX's Transporter-16 mission at the end of March. Momentus supported the effort by hosting the payload on its Vigoride platform, helping integrate the demonstration for launch, and providing communications, power, imaging, and other support services during the demo. The space payload was completed, tested, and delivered to the payload host, Momentus Inc., in less than 12 months. "Developing a payload of this complexity on such a short timeline was an enormous undertaking for our small team," says Pellegrino, who is also co-director of the Space Solar Power Project, which aims to harvest solar power in space and wirelessly transmit it to Earth's surface. "As we wrap up the mission, we are finally able to start thinking about the new avenues of research opened by this demonstration."

The on-orbit demonstration also illustrates the speed at which maturing space technology can transition from lab to life. NOM4D was not initially structured around an on-orbit demonstration. As promising results emerged from program performers in Phase 2, Detor decided to pivot the final phase of the program to pursue a space demo. "It's the speed and the scale that made this a DARPA project. We went from the idea of an on-orbit demo to launching a working prototype into space in 15 months," Detor said. "Operating in space is much harder than operating on the ground – there's virtually no margin to address issues that may arise. Testing in the operational environment is instrumental to rapidly maturing the technology."

The NOM4D program has at least one more milestone ahead before it concludes. Later this year, the NOM4D team from University of Illinois Urbana-Champagne (UIUC) will launch a project to the International Space Station. Instead of in-space assembly, the Illinois project will demonstrate a novel approach to composite material processing in space. For the first time, the UIUC team will test a highly-engineered, space-compatible resin system designed for energy-efficient polymerization to produce a high-strength composite structure in space. As NOM4D winds down over the next few months, the program aims to help jumpstart ambitious ideas and big investments in space manufacturing and assembly.