The postponement of the launch on Wednesday means that NASA astronauts Butch Wilmore and Suni Williams will have to wait at least two more days before they can begin their return to Earth.

Wilmore and Williams arrived at the ISS in June for a mission that was supposed to last 10 days at most, but the pair were forced to extend their stay after their Boeing Starliner spacecraft developed propulsion issues. Wilmore and Williams are scheduled to return to Earth on board a SpaceX Dragon spacecraft currently docked at the ISS once a team of American, Japanese and Russian astronauts arrives to take their place.

NASA said in a statement that Wednesday’s launch at the Kennedy Space Center was scrubbed due to a hydraulic system issue with a ground support clamp arm for the Falcon 9 rocket. The space agency said it was working to address the hydraulic system issue and planned to reattempt the launch on Friday. The Crew-10 team consists of NASA astronauts Anne McClain and Nichole Ayers, Japan’s Takuya Onishi, and Russia’s Kirill Peskov.

If the mission goes ahead on Friday, Wilmore and Williams could depart the ISS by March 19, according to NASA. In a call with reporters earlier this month, Williams said she was looking forward to reuniting with her family. “It’s been a roller coaster for them, probably a little bit more so than for us,” Williams said. “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.” (Aljazeera)