NASA's Jessica Meir and ESA's Sophie Adenot to step out of ISS tomorrow for U.S. Spacewalk 99—here's all you need to know
Note: The article was updated at 1:14 am EDT on September 1, 2026, with the correct spelling of "Peggy Whiston."
Spacewalks may look routine from Earth, but there is a lot of work packed into every trip outside the International Space Station. NASA astronaut and station commander Jessica Meir and ESA's Sophie Adenot are set to head outside the station tomorrow, September 1, for several maintenance tasks, and NASA will provide live coverage of the extravehicular activity (EVA).
When will the spacewalk begin?
Meir and Adenot are expected to begin the approximately six-and-a-half-hour-long U.S. Spacewalk 99 at about 8:30 a.m. EDT. It will mark the seventh spacewalk for Meir, who will move into the third position for the total number of spacewalks among female astronauts at NASA, behind only Peggy Whitson (10) and Suni Williams (9). Meir was, in fact, part of the first all-woman spacewalk in October 2019, when she and NASA astronaut Christina Koch spent 7 hours and 17 minutes outside the station replacing a failed battery charge-discharge unit. More recently, Meir ventured outside the station on August 6 for U.S. Spacewalk 96, spending 6 hours and 27 minutes with NASA astronaut Anil Menon preparing the station's power system for the future installation of roll-out solar arrays.
Adenot will meanwhile be venturing out for her third spacewalk outside the orbital laboratory. Having arrived at the station in February with Meir and the rest of Crew-12, she made her spacewalk debut on August 18 and went out again a week later on August 25. She was accompanied by Menon on both occasions.
Where to watch the NASA spacewalk live?
NASA will start the live coverage at 7 a.m. EDT, streaming the spacewalk on NASA+, YouTube, X, Amazon Prime and Discovery+. Viewers will be able to tell the astronauts apart by their suits: Adenot will wear red stripes, while Meir's suit will be unmarked.
What will the astronauts do during the spacewalk?
Meir and Adenot will have several tasks to complete outside the International Space Station. One of the main tasks is replacing a retroreflector on the forward port of the station's Harmony module. The device will help spacecraft with navigation during rendezvous and docking operations.
They will also install jumper cables for the station's data-relay systems. These cables will connect equipment used to support communications. Another task involves preparing the Alpha Magnetic Spectrometer's radiator for future maintenance. The instrument looks for antimatter and dark matter. During the same spacewalk, the astronauts will also replace a high-definition camera on the station's truss.
Why are spacewalks and maintenance tasks important?
The International Space Station has been operational for over two decades, and some of its equipment needs repair and maintenance as it gets older. While astronauts can reach some equipment from inside the station, other parts can only be worked on during a spacewalk, which sees astronauts venture outside the station. The excursion tomorrow will mark the 284th spacewalk overall conducted in support of space station assembly, maintenance, and upgrades.
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