If there's one thing we know about humans and space, it's that the less time we spend floating in a radiation-filled vacuum, the better.

A robot designed by Caltech and funded by DARPA has recently demonstrated a potential solution to space construction by assembling an antenna's truss from individual components in orbit. Researchers have described it as the first autonomous construction of a structure in space.

Think flat-pack furniture, only with more expensive delivery.

A key part of the Autonomous In-Space Tensioned Reflector Assembly project, or ASTRA for short, the robotic builder was meant to build a 1.4-meter-wide (4.6-foot) reflector antenna from an assortment of composite tubes, aluminum joints, and reflective film.

Time limitations restricted the robot's task to a single support. Two truss sections traveled up pre-assembled; the robot then assembled a third.

It might not be a complete communications dish ready to phone home, but according to Andrew Detor, program manager for DARPA's Novel Orbital and Moon Manufacturing, Materials and Mass-efficient Design (NOM4D) program, the demonstration is a significant step towards building massive structures in space kilometers in scale.

"Nothing approaching that scale can be achieved today," says Detor.

NOM4D's broader vision involves shipping raw materials into orbit and manufacturing structures designed for life in space. Antennas, optics, and solar arrays could then be engineered around their working environment, with less emphasis on surviving launch as finished structures. 

DARPA likens the approach to Tinkertoys or K'Nex. Repeating a relatively straightforward construction sequence could eventually produce structures far larger than the machine doing the building. 

"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," explains Detor.