The Boeing Starliner astronauts stranded in space for nearly three months are going to have to be there a little longer ... 'cause they're not going to be earthbound until next year.

During a newsconference Saturday, NASA administrator Bill Nelson explained Butch Willmore and Suni Williams are expected to return in February 2025 ... while the Boeing Starliner will be returned unmanned out of concern for their safety.

That's six more months for the pair in space ... a far cry from the nine days their mission was originally scheduled for.

Remember ... the two astronauts went up back on June 5 with a return date for June 14 -- but, helium leaks and propulsion problems left them stuck at the International Space Station.

NASA was considering whether the two could fly back on the Starliner and Boeing was sure they could ... but, NASA won the argument, and the team's stuck until February or March.

Now, a SpaceX ship's going to take the crew back ... but, it's going to take six months to happen, when the next SpaceX Dragon mission comes to an end. Two people will pilot the four-person craft on the way up and take the astronauts home after their mission's finished.

One issue ... the astronauts stuck in space have gear compatible with the Starliner and not the Dragon coming to get them -- so, they'll need new spacesuits.

NASA's tried to emphasize the two astronauts aren't actually stranded in space ... though, it's hard to see it any other way since they can't seem to get them down.