A robot in orbit has assembled an initial section of a structure without astronauts, offering an early demonstration of how future spacecraft parts might be built in space. The system did not finish its planned reflector antenna, however, and the test does not show that much larger structures can yet be assembled reliably.
A ScienceDaily report published on November 9, based on materials provided by the California Institute of Technology (Caltech) and originally written by Kimm Fesenmaier, describes the Autonomous In-Space Tensioned Reflector Assembly, or ASTRA. Caltech researchers developed the system with funding from the Defense Advanced Research Projects Agency (DARPA), as part of its Novel Orbital and Moon Manufacturing, Materials, and Mass-efficient Design program. Sergio Pellegrino leads the ASTRA demonstration.
ASTRA spent six months in orbit attempting to build a reflector antenna designed to measure 1.4 meters across. Its robotic arm retrieves structural tubes and connecting joints from storage dispensers and joins them into repeated sections called bays, which form a supporting framework, or truss. The robot carried out assembly operations automatically, while a team on Earth sent instructions and monitored images of its progress.
The payload included two truss bays assembled before launch. In orbit, the robot extended those sections and attempted to construct another. Technical difficulties and scheduling constraints prevented the team from completing the antenna. The report says the successful assembly of an initial section provides evidence that this construction approach can work in orbit, while making clear that the full antenna was not built.
The antenna design calls for 11 connected bays and a reflective surface made from perforated Kapton film, held in tension as two cable nets. The source describes this as the intended design; the report does not say the robot completed that reflector. The team encountered problems in orbit and used a backup system in Pellegrino’s laboratory to recreate issues and work out revised instructions. Communication opportunities with the robot came in brief windows, roughly seven or eight times a day, each lasting about 15 minutes.
Building structures in orbit could help address a constraint of spaceflight: components must fit inside a rocket’s payload enclosure, or fairing. Engineers can fold structures for launch or send components for astronauts to assemble, but the report says both approaches impose practical limits. Robotic assembly offers another possibility: send materials into orbit and build the larger structure there.
That possibility could eventually matter for telescopes with larger reflective surfaces, radio antennas, and solar arrays. Larger telescope mirrors could collect more light, while large antennas could support communications systems. The report presents these as potential applications, not capabilities established by the ASTRA demonstration.
DARPA’s NOM4D program is investigating construction at much greater scales. Program manager Andrew Detor described its objective as structures hundreds of meters or kilometers in scale, while saying nothing approaching that scale can be achieved today. ASTRA’s partial assembly is a step toward testing the idea, not a demonstration of kilometer-scale construction. The next challenge is to make the process more reliable and establish how far it can scale.