A robot has built a structure in space without assistance from human astronauts for the first time. The milestone was achieved by a robotic system known as Autonomous In-Space Tensioned Reflector Assembly, or ASTRA.

The system has spent the past six months in low Earth orbit. During that period, it has remained mounted to Momentus Inc’s Vigoride 7 orbital service vehicle.

ASTRA’s assignment was to construct a circular radio antenna measuring 1.4 meters, or 4.5 feet, across. The machine carried out its work using components transported into orbit rather than a completed antenna assembled on Earth.

Those components included fiber tubes, aluminum joints and reflective surfaces made from Kapton. The durable polymer film is commonly used in space travel.

ASTRA uses a manipulator resembling an arm to pick up the individual components and move them into position. That capability allows the system to conduct the assembly work without direct help from astronauts.

The structure is assembled one segment at a time. After each section is completed, it is unfurled to create a lined scaffolding that curls around the original module.

The California Institute of Technology, also known as Caltech, and DARPA designed the ASTRA robot. The system has been compared with an autonomous construction kit similar to the model building toys used by children.

Andrew Detor, program manager of the Novel Orbital and Moon Manufacturing, Materials and Mass-efficient Design program at DARPA, described how the assembly process works. The program is known as NOM4D.

“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 in a statement.

“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.”

That process links the construction and deployment stages within the same automated system. Completed sections are released as they become ready, gradually extending the structure around the module.

The first mission has not proceeded without difficulties. The project has encountered multiple challenges during its debut in orbit, although the researchers did not provide many details about what those problems involved.

Those hurdles have placed the complete assembly in doubt. It now appears unlikely that the demonstration will finish the entire structure before the mission ends in December.

Despite the difficulties, the achievement is being treated as a proof of concept. Researchers continue to hold high hopes for what the technology could eventually accomplish.

The broader goal is to transport components into space and have robots assemble them within the space environment. This approach could support the construction of structures that are larger than the equipment currently being assembled by ASTRA.

Potential projects identified by the researchers include large solar arrays and sprawling radio antennas. Detor also pointed to space depots and habitats as examples of structures that could benefit from the program’s approach.

Such a system could change the established practice of building space equipment on Earth before launching it into orbit. That method may eventually appear antiquated if autonomous orbital assembly develops as envisioned.

“In a future space economy, we’re going to need large things,” Detor added.

“Think large space depots or habitats, large solar arrays to collect power, or large radio antennas to explore the edges of the universe. Those things require size, and NOM4D gives us a path to accelerate creation of new capabilities.”