The ASTRA robot, built at Caltech, autonomously assembled a section of structure in orbit without the involvement of astronauts. The Defense Advanced Research Projects Agency (DARPA) called it the first demonstration of automated assembly in space.
The information was announced on November 5 by DARPA, which wrote in a post on X that its NOM4D program, together with Caltech, had demonstrated the first automated assembly of a structure in outer space.
What the robot built
According to DARPA, the Caltech payload built a truss from individual elements in orbit. A relatively simple gantry robot, moving along three linear axes, joined composite elements using specially designed connectors. At the same time, it unrolled a thin reflective mesh, which is meant to serve as proof of concept for future space antennas.
Caltech says ASTRA launched with two ready truss segments. These were pushed out of the device, and then the robot built a third segment. The complete truss is to have 11 segments, connected to mesh reflectors and pushed outward.
Launch and mission parameters
ASTRA stands for Autonomous In-Space Tensioned Reflector Assembly. The demonstrator was ultimately intended to build an antenna reflector 1.4 m in diameter from composite tubes, aluminum connectors and a reflective Kapton surface. The device, with a volume of about 1 m³, launched on March 30, 2026 from Vandenberg Base as one of 10 payloads on Momentus’s Vigoride 7 orbital vehicle. The vehicle was carried on the SpaceX Transporter-16 mission.
The team is led by Prof. Sergio Pellegrino. The project is one of two that advanced to the third phase of NOM4D, which consists of small-scale orbital demonstrations. The second is run by the University of Illinois Urbana-Champaign and concerns extrusion of composites.
Plans and limitations
The ASTRA mission is set to end in December. The Caltech team acknowledges that it will no longer be possible to assemble a complete truss. However, it believes the experience gathered confirms the feasibility of the approach, and that the design needs to be simplified and refined.
NOM4D program manager Andrew Detor stated that the goal of the program is “efficient, scalable construction of very large structures in space”. He also added that 15 months passed from the idea of an orbital demonstration to the launch of a working prototype. The program started in 2022, and its premise is to send lightweight materials into orbit and build structures from them on site, instead of launching finished structures limited by rocket size.
We wrote about other US activity in orbit in our article on the confirmation of American weapons in Earth orbit.
