NASA and SpaceX on Tuesday postponed the Crew-9 mission to the International Space Station (ISS) no earlier than Saturday, citing unfavorable weather forecast.

What Happened: SpaceX's Falcon 9 rocket is now expected to launch the mission to ISS from Florida with Nick Hague and Aleksandr Gorbunov aboard the Dragon spacecraft no earlier than Sept. 28 at 1:17 p.m. EDT. The change in the timeline, NASA said, is due to tropical Storm Helene's expected unfavorable impact on weather conditions at the launch site on Thursday.

The Crew-9 mission will be NASA's ninth crew rotation mission with SpaceX to the ISS under its Commercial Crew Program. The mission has undergone significant changes over the past few months.

Why It Matters: SpaceX's Crew Dragon spacecraft was initially scheduled to launch to the International Space Station (ISS) with four astronauts on Aug. 18 as part of the Crew-9 mission.

However, NASA first delayed it to Sept. 24 due to delays with the Boeing (BA  ) Starliner mission launched on June 5. Starliner and the two astronauts aboard the spacecraft - Sunita Williams and Butch Wilmore - were supposed to return in about eight days. However, technical issues identified with the spacecraft while docking delayed a return, and the space agency subsequently decided to scrap bringing back the two astronauts on the Starliner spacecraft.

The Starliner subsequently returned without the astronauts on Sept. 6. Williams and Wilmore, who are currently at the station, will join Hague and Gorbunov on their return journey to Earth in February 2025.

NASA astronauts Zena Cardman and Stephanie Wilson, who were previously slated to fly on Crew 9 but were dropped to make space for Williams and Wilmore, will now be reassigned to a future mission, according to NASA.