I'm afraid this might be too broad, but I remember watching this old show on US TV (basic cable) in the late 1980's or early 90's, but it looked even older, perhaps from the 1950's to 1970's. Portions may have been in black and white. (or that may be my faulty memory) I don't know if it was a series or a one-off special.
It had segments with a man speaking about the solar system, and the future of space travel. The man was in a science classroom. He explained some concepts and wrote some words on a chalk board. Then the presentation switched to an animation of a space ship exploring the solar system. The presenter explained that this ship is powered by nuclear fusion and is able to scoop up fuel from space. The design of the ship was reminiscent of Star Trek. It had a saucer where the crew lived, and then an engine "tube" extending down from the bottom-middle of the saucer. The tube then tapered back up at the end.
One distinct memory I have is of the ship orbiting Jupiter.
The show may have been interspersed with dramatic sci-fi segments, or the parts I'm remembering might have been short educational segments and part of a longer sci-fi series.
This TV show sparked my imagination in space travel and science-fiction. Does anyone else remember this?