A prototype humanoid robot delivered to the International Space Station during one of the final space shuttle flights more than three years ago finally has been outfitted with legs.

Station commander Steve Swanson did the honors before the Labor Day weekend, then powered down the robot, known as Robonaut, or R2, and put it away.

Mobility tests likely won’t begin until November, as Robonaut’s human companions have two cargo ships due to arrive in September and October and a couple of spacewalks to prepare for.  The orbital outpost also will be getting three new crewmembers this month. Swanson and cosmonauts Alexander Skvortsov and Oleg Artemyev are due back home on Sept. 10. Replacements arrive Sept. 25.

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NASA and General Motors developed Robonaut to work alongside people, whether in space or at manufacturing plants on Earth. The station’s robot includes a human-like head, arms, hands and torso that was mounted on stanchion in the Destiny laboratory module.

Robonaut is designed to handle the same tools and equipment astronauts use. Future versions may one day accompany crewmembers on spacewalks outside the station, or handle tasks too dangerous or difficult for humans.

Instead of feet, Robonaut’s new legs have grippers that can attach and navigate along handrails. In space, “you want legs that are going to give you more of a climbing capability than a walking capability,” Robonaut lead researcher Ron Diftler said in a NASA TV interview.

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The legs are longer than human legs and have more degrees of freedom and greater flexibility so that the robot can reach distant handrails, he added.

Robonaut’s legs were flown to the station aboard a SpaceX cargo ship in April.

An Earth-bound Robonaut model with prototype legs. NASA didn’t release new pictures of the upgraded robot, citing intellectual property restrictions. Credit: NASA.