This is a show that recently came through my mind and that i haven't seen in almost 2 decades.
Starship Sagittarius (in japan called Uchusen Sagittarius) was a sci-fi anime that aired in 1986-1987 for 77 episodes.
The series depicts the adventures of four astronauts who travel through space and visit many planets. On each planet they have an adventure. Each adventure seems to have a sort of morality, like the importance of friendship or about the state of the enviroment.
It had alot of humor in it, but it also dealt with very mature themes at some points. like war, the dangers of nuclear wars, protection of the enviroment, slavery, alcoholism, etc. This all sounds very serious but it*s done in a way that kids can still watch this.
I just recently found the japanese dub with subtitles on it on Youtube with all 77 episodes. It's a very interesting show to say the least.