You know, I was just sleeping and having a dream about a huge generational spaceship, with separate hanging living complexes, which carries most of the population of Earth away to a distant world. Then I realized, I'd seen this concept before on TV, when I was a kid. Reaching through my own memory banks to the distant past, I could only come up with the words: "lost", "ark", and "Walter Koenig" (Chekov from Star Trek). Did the search for Koenig through IMDb, and sure enough found this entry. If I had instead done a search for "lost" and "ark", I'd have probably ended up in "Raiders of The Lost Ark", so it's a good thing I didn't do that search. :-)
Wow, now that I'm looking at the list of stars of this show, I am surprised by how many of them are well-known. Walter Koenig was just a guest star on it. I didn't realize that one of the stars was Keir Dullea, Dave from 2001: A Space Oddessy. Also Robin Ward, I remember he used to be a weatherman or something later on. Ah, ancient Canadian memories.
Koenig seems to have a knack for memorable guest appearances on sci-fi shows. He also had a memorable turn as Bester on Babylon 5.