CALGARY — NASA astronauts are scheduled to venture outside the International Space Station (ISS) Tuesday to replace a malfunctioning joint on Canadarm2, the Canadian-built robotic arm that has become indispensable to station operations over the past quarter century.The planned spacewalk comes after engineers detected elevated electrical current in one of Canadarm2's wrist joints during routine operations in May. Rather than risk additional wear, mission controllers placed the arm in a safe configuration while developing a repair plan.NASA Astronauts Chris Williams and Jessica Meir are planned to remove the faulty joint, install a spare replacement already stored aboard the station and test the system before returning it to service.Canadian Space Agency (CSA) astronaut Jenni Gibbons will serve as CAPCOM, communicating directly with the astronauts throughout the repair..Since arriving at the station in 2001, the 17.6-metre robotic arm has helped assemble the ISS, captured dozens of cargo spacecraft, supported countless spacewalks and moved massive station components that astronauts could not safely handle on their own.Unlike the original Canadarm used aboard NASA's Space Shuttle fleet, Canadarm2 can "walk" around the station by releasing one end and attaching itself to another grapple fixture, allowing it to access nearly every exterior surface of the orbiting laboratory.Canadarm2 has also proven the strength of Canadian engineering. In 2017, astronauts replaced one of the arm's end effectors after years of service, extending its operational life. In 2021, it was struck by orbital debris but sustained only minor damage and continued functioning. More than 25 years after it was built, Canadarm2 remains one of the ISS's most reliable and important pieces of equipment..This will be the fourth time the space arm will be in repair, with the first time being in 2002.The spacewalk is expected to last approximately six hours and 40 minutes as astronauts work to replace the faulty joint and return Canadarm2 to full operation.If the repair is successful, Canadarm2 will return to service, continuing the critical work it has performed aboard the ISS for more than 25 years. From capturing cargo spacecraft to supporting spacewalks and moving massive station components, the Canadian-built robotic arm remains one of the station's most essential pieces of equipment.