If there was any singular reason why Space Stars was cancelled after 1 season, it would be the square peg in the round hole that was Astro & the Space Mutts.
Spun off from The Jetsons, Astro (Don Messick) was rebooted as a comic sidekick to Space Ace (Michael Bell), and with some new canine pals, to boot. For serious superhero fans, this was the kitchen break part of the show, if you will, a campy comedy relief segment amidst the exploits of Space Ghost, The Herculoids, & The Teen Force.
Now, scope out the opener, "Night of the Crab":
Clearly, Astro just didn't fit in, and would return when The Jetsons was revived in 1985. If Hanna-Barbera really wanted this to work, Astro would've been a stand-alone series instead.