In the hands of Hanna Barbera, a Tom and Jerry cartoon set in space could have been a lot of fun; in the hands of Gene Deitch, it's sheer torture, with the low, low standards that go with farming out the series to an animation studio in Czechoslovakia, where not one person involved understands what made the original cartoons so much fun.
In this sorry mess, Jerry is fed up with Tom trying to kill him, so volunteers to be an Astro-mouse: as the advert in Jerry's newspaper says, in space there are no cats. By total accident, however, Tom finds himself shot into space with Jerry and the mayhem continues. As with the previous Deitch cartoons, the animation is atrocious and the sound effects abysmal (although, I guess, at least some of the echoey, bleeping noises kinda suit the space theme).