But I don't remember being impressed by it.

And of course, a few years later, the advent of "Star Wars" would change science fiction/science fantasy memorably, and forever.

I’ve watched episodes here and there. I like old scifi from the 50’s through the 70’s.

In the episode I think you are referring to, they all come back.

Space 1999 had tangled history. Decades after the show ended, the short Final Message from Moonbase Alpha has them finally finding a world to settle on.

https://en.wikipedia.org/wiki/List_of_Space:_1999_episodes

Let me know if it works

Boy, if only we’d been so advanced by that year. I remember watching the show as a teenage stoner in the 70s. Martin Landau and Barbara Bain, real life couple and finding work after Mission Impossible, lost on our moon gone rogue. Seeing a rerun in later years, kinda found classically 70s cheezy. Never knew how it ended.

it had one kick-ass disco theme!

Well, I know another thing: when I was a kid I had a plastic Eagle toy that I played with all the time. It was more than two feet long and the control capsule could separate from the rest of the ship to form a smaller ship.