NASA astronauts operate on space station's broken robot arm

Two NASA astronauts floating outside the International Space Station carried out a bit of orbital surgery Tuesday, successfully replacing a broken 200-pound "wrist" joint near the end of the lab's 58-foot-long robot arm. "That is a good install, you guys. I know that was tough. Wonderful work," Canadian astronaut Jenni Gibbons called up from mission control toward the end of the seven-hour, 20-minute excursion. Astronaut Chris Williams shows a "strong man" pose 260 miles above Earth during a break in work to repair the International Space Station's robot arm. NASA On May 27, flight controllers at the Johnson Space Center in Houston noticed one of the Canadian-built arm's seven joints was drawing more current than expected and not moving properly. After a detailed review of telemetry, NASA managers and experts with the Canadian Space Agency, which supplied the station arm, concluded the joint had failed and needed to be replaced with a spare, one of two mounted on an external stowage platform. "Systems like Canadarm2 were designed from the beginning with replaceable components and were planned with maintenance in mind," ISS operations and integration manager Bill Spetch said. "This is no exception." Floating in the Quest airlock, astronaut Jessica Meir, making her fifth spacewalk, and crewmate Chris Williams, making his second, switched their spacesuits to battery power at 8:20 a.m. ET, officially kicking off the year's third ISS spacewalk and the 280th overall. …