When will NASA astronaut Sunita Williams return to Earth?

NASA and SpaceX postponed the launch of a replacement crew of four astronauts to the International Space Station (ISS) on Wednesday, delaying the long-awaited return of US astronauts Butch Wilmore and Sunita Williams.

The Crew-10 mission, set to launch from Florida aboard a SpaceX rocket, was intended to replace the current crew on the ISS and facilitate the return of Wilmore and Williams, who have been stranded in space for nine months following their trip on Boeing’s faulty Starliner spacecraft.

NASA announced that the launch was called off due to a hydraulic system issue with the Falcon 9 rocket's ground support clamp arm. The space agency said that launch teams are working to resolve the issue before setting a new launch date.

When will Sunita Williams return to Earth now?

NASA has announced a revised launch target for no earlier than 7.03 pm EDT (2303 GMT) on Friday (4.33 am IST on Saturday) after postponing Wednesday’s attempt due to high winds and rain forecast along Dragon's flight path.

NASA said that if the Crew-10 mission launches on Friday, the Crew-9 mission, carrying astronauts Wilmore and Williams, is expected to depart the International Space Station (ISS) on Wednesday, March 19.

The mission was moved up by two weeks following calls from US President Donald Trump and his adviser, SpaceX CEO Elon Musk, to bring Wilmore and Williams back earlier than originally scheduled.

Wilmore and Williams, both experienced astronauts and U.S. Navy test pilots, have seen their mission extend far beyond the planned eight-day stay on the ISS. Their Starliner spacecraft returned to Earth without them last year.

Initially, SpaceX’s Crew-10 mission was set to lift off from the Kennedy Space Center in Cape Canaveral at 7.48 pm ET (2348 GMT) on Wednesday – means 6.18 am IST (Indian Standard Time) on Thursday – carrying a crew of two US astronauts, one Japanese astronaut, and one Russian astronaut.

What were Wilmore and Williams doing in ISS?

NASA said Wilmore and Williams have been engaged in research and maintenance aboard the ISS alongside other astronauts and remain safe.

During a March 4 call with reporters, Williams expressed her excitement about reuniting with her family and pets after returning home.

“It's been a roller coaster for them, probably a little bit more so than for us,” Williams said about her family. "We're here, we have a mission - we're just doing what we do every day, and every day is interesting because we're up in space and it's a lot of fun."

NASA clarified that Wilmore and Williams must remain on the ISS until Crew-10 arrives to ensure the station has enough US astronauts for essential maintenance.

The two astronauts arrived at the ISS in June as part of Boeing's first crewed test flight of the Starliner spacecraft. However, after encountering propulsion system failures in space, NASA determined that using the Boeing craft for their return would be too risky. As a result, plans were made to bring them back to Earth using a SpaceX capsule.