NASA astronaut Jessica Meir and ESA astronaut Sophie Adenot concluded their spacewalk outside the International Space Station at 3:29 p.m. EDT on Sept. 1, 2026, after 6 hours and 49 minutes, NASA reported that day. The pair installed a new retroreflector on the forward port of the Harmony module to support spacecraft navigation during rendezvous and docking, and replaced a high-definition camera on the station's truss.

They also swabbed the station's exterior for microorganisms and partially completed installing jumper cables for electrical systems. Separately, the crew began preparing for replacement of the Alpha Magnetic Spectrometer's heat-rejecting radiator on a future spacewalk. Mission Control deferred installing the remaining guide studs for that radiator so engineers could develop a plan to finish the work on a later spacewalk, and shifted remaining jumper cables and other noncritical tasks to a later date as the timeline slipped.

Adenot reported some mobility issues with her left arm during the spacewalk; Meir inspected the suit and determined the glove heater harness was likely catching, limiting movement in the left shoulder joint. Unzipping the joint appeared to resolve the issue before the crew re-entered the airlock. NASA described the outing as U.S. spacewalk 99, Meir's seventh and Adenot's third, and the 284th in support of space station assembly, maintenance and upgrades. Meir now ranks third among women at NASA for total spacewalks, behind Peggy Whitson (10) and Suni Williams (9).