I kept on hearing that Mission: Impossible will be filmed in the International Space Station. Is there a truth to this? The next Mission: Impossible is a back to back part 7 and 8, so would this be for both movies or just a very short film?
Deadline, who first reported the story about Tom Cruise planning to shoot a movie aboard the ISS, stated (albeit without providing a source) that the planned project was "not a Mission: Impossible film". Mission: Impossible 7 had already begun filming prior to the announcement, and I can find no details regarding Mission: Impossible 8's filming schedule at all, let alone any sources linking it to the ISS project.
So no, currently there is nothing to suggest that the film Tom Cruise plans to shoot aboard the ISS is a Mission: Impossible film. It's not impossible (pun intended) for it to be Mission: Impossible 8, but all the signs so far point to it being a completely separate project.