There are sub genres of SF yet they have very blurred lines defining them. Star Trek
is space adventure and/or space opera in usually the best or better sense. Very few other space adventure works have come off as well overall.
isn't only space adventure or opera, but as was once said it's very much science fantasy. That isn't to say it cannot be enjoyed on its own terms, but it's evident that its science isn't meant to be taken seriously or to appear at least passably credible. And, sadly, most space adventure/opera leans more towards the SW approach.
I think it's often thought that hard SF doesn't often translate well into engaging and interesting storytelling because it's thought that the science aspect is restrained strictly to pretty much what is known, and if you go by something like 2001
then you might have a point. But even 2001
delved into things only speculated about. 2001's
(the film) flaw isn't ideas but rather slow pacing and bland characters, which were intentional, but then the result is the film is challenged to hold most people's attention.
I really think it's possible to do space adventure that deals with real and speculative science and still pull it off in an engaging and credible way without being plodding and also not being tempted with fantasy science. Star Trek
and a few others have periodically done this and it's exciting when they have.