Astronauts begin spacewalk to improve navigation to the International Space Station

Jessica Meir and Sophie Adenot stepped outside the International Space Station on Tuesday for a spacewalk expected to last about six and a half hours.

Their main task is to replace a reflector on the forward port of the Harmony module. The device helps visiting spacecraft orient themselves as they approach and dock with the station.

The astronauts are also scheduled to install jumper cables to strengthen data relay systems and replace a high-definition camera on the orbital laboratory’s structure. They will prepare the radiator of the Alpha Magnetic Spectrometer, a cosmic-particle detector that has searched for traces of dark matter and antimatter outside the station since 2011.

Meir, an American and the station’s commander, will work from the Canadarm2 robotic arm, operated from inside the station by astronaut Anil Menon. Adenot, a French astronaut, will move along the exterior while tethered to the laboratory. Flight engineer Jack Hathaway will monitor the work and assist with their spacesuits.

The mission is Meir’s seventh spacewalk and Adenot’s third. It is the 284th spacewalk supporting the station’s assembly, maintenance and upgrades, and the 99th conducted by U.S. astronauts. Meir now ranks third among NASA astronauts for the number of spacewalks, behind Peggy Whitson and Suni Williams.