Caltech's ASTRA robot assembles a third reflector section in orbit; 11 sections were planned

A robotic payload from Caltech has assembled part of a reflector antenna in low Earth orbit, according to knowridge.com. The payload, ASTRA (Autonomous In-Space Tensioned Reflector Assembly), launched on March 30, 2026, aboard Momentus's Vigoride 7 vehicle on SpaceX's Transporter-16 mission. It was one of ten payloads carried by the host vehicle. knowridge.comknowridge.comknowridge.comOpen source ↗

What ASTRA did in orbit

ASTRA was developed under DARPA's NOM4D program. The intended demonstration was a reflector antenna about 1.4 meters across, made of composite tubes, aluminum joints and a lightweight reflective surface. After the payload reached orbit, the team sent commands through the host spacecraft to release restraints and start assembly operations.

The builder carried two sections that had been made on Earth. It deployed them and constructed a third section in orbit, so the demonstration covered an assembly step rather than the unfolding of a fully prebuilt structure. A robotic manipulator picks up components, places them on an assembly plate and joins them into a section. The design then attaches a perforated reflective film held under tension by springs and pushes completed sections outward. The payload carries 11 cameras, which let the team inspect construction and identify problems from the ground.

The film was developed with collaborators at the University of Pennsylvania. It needs less tension than some conventional knitted reflector meshes, which could allow lighter supporting structures. knowridge.comknowridge.comknowridge.comOpen source ↗

Troubleshooting and limits

Solving problems required considerable work on Earth. The team used a duplicate builder in the laboratory to reproduce faults, test solutions and prepare revised instructions, which were sent during short communication windows with the spacecraft.

The planned structure comprises 11 sections. The team reported that completing it before the end of the mission appeared unlikely. The result therefore shows a viable assembly approach and, at the same time, the need to simplify and refine the mechanism.

Larger reflectors, communications antennas or solar arrays are named as possible future uses, but they remain goals. The demonstration tested construction, not a functioning telescope or power system. The initial orbital assembly will help engineers decide how to improve the next design. knowridge.comknowridge.comknowridge.comOpen source ↗