NASA astronauts operate on space station's broken robot arm

Two NASA astronauts performed intricate "orbital surgery" outside the International Space Station, successfully replacing a critical 200-pound "wrist" joint on the station's 58-foot-long robot arm. The seven-hour, 20-minute spacewalk marked the third ISS excursion of the year and the 280th overall.

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That is a good install, you guys. I know that was tough. Wonderful work.

Astronauts Jessica Meir and Chris Williams, floating 260 miles above Earth, began their task by switching their spacesuits to battery power. They then set up foot restraints and positioned the spare joint for installation. The complex procedure involved detaching the arm's "hand," known as the latching end effector (LEE), along with two other functional joints. This 900-pound assembly was temporarily stored on a nearby shelf to allow for the removal of the failed joint, identified as joint No. 5.

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Systems like Canadarm2 were designed from the beginning with replaceable components and were planned with maintenance in mind. This is no exception.

The replacement joint was secured in place approximately four and a half hours into the spacewalk. Mission control confirmed the successful installation, with Canadian astronaut Jenni Gibbons commending the crew's "wonderful work" on a "tough" task. Following the joint replacement, Williams and Meir reattached the LEE cluster. Flight controllers later powered up the arm, verifying good electrical connections through the newly installed component.

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We'll remove the failed joint five, replace it with the spare joint and then once that's back on the arm, our last major task will be to get that LEE cluster that we temporarily stowed and put it back onto the robotic arm so that we have a fully assembled arm at the end of the spacewalk.

Flight controllers at the Johnson Space Center in Houston first noticed issues with the Canadian-built arm's joints on May 27. Telemetry data indicated one joint was drawing excessive current and not moving correctly. After a thorough review involving experts from NASA and the Canadian Space Agency, which supplied the arm, managers concluded the joint had failed and required replacement with a spare from an external platform. Bill Spetch, ISS operations and integration manager, noted that systems like Canadarm2 were designed with replaceable components and planned maintenance in mind.

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Today we did hear good confirmation that ... Canadarm2 has two good strings of power and data to the arm. So today's wrist surgery was successful.