Two NASA astronauts will fix the International Space Station's big robotic arm during a spacewalk on Tuesday (June 30), and you can watch the action live.Chris Williams and Jessica Meir will perform a roughly 6.5-hour spacewalk outside the International Space Station (ISS) today, starting at about 8:35 a.m. EDT (1235 GMT).You can watch it live via NASA; Space.com will air the stream as well, if the agency makes it available. Coverage will begin at 7:00 a.m. EDT (1100 GMT).Williams and Meir will replace a 200-pound (90-kilogram) wrist joint, which malfunctioned "during normal Canadarm2 operations on May 27 after the arm drew elevated motor current and did not move as expected," NASA officials wrote in a June 22 spacewalk preview.The spare joint was already on board the ISS, which has been continuously occupied by rotating astronaut crews since November 2000."Repairs to robotics, like Canadarm2, are normal and expected after more than 25 years of continuous operations, as the system was designed with replaceable components and planned maintenance in mind," NASA officials added in the preview.Canadarm2 is nearly as old as the ISS. The 56-foot-long (17-meter-long), 3,300-pound (1,500-kg) robot arrived at the orbiting lab aboard the space shuttle Endeavour in April 2001.The upcoming extravehicular activity (EVA) will be the second for Williams, who will be "spacewalk crewmember 1" and will wear a spacesuit with red stripes. It will be the fifth for Meir, who will be "spacewalk crewmember 2" and will wear a suit with no stripes.The duo performed an EVA together this past March, spending seven hours prepping the orbiting lab for a new solar array.Astronauts have performed a total of 279 spacewalks outside the ISS to date.