Zombies of the Stratosphere (1952)

Martians come to Earth to build an H-bomb strong enough to blast Earth out of orbit so that Mars can be moved into its place in closer proximity to the sun. Super-scientist Larry Martin, inventor of the first stratospheric-flight spaceship as well as a jet-powered personal flying suit with helmet, is called upon by the government to investigate ramped-up UFO reports occasioned by the Martians' spaceships. The Martians, meanwhile, led by Marex, engage a renegade earth scientist and a gaggle of gangsters to help them steal supplies, operate a menacing robot, and build their bomb. This movie serial in 12 chapters was originally planned as a sequel to "Radar Men From The Moon" with Commando Cody as the hero but at the last moment the main characters' names were changed and all other references to that serial removed from the script.

Unfortunately the movie Zombies of the Stratosphere is not yet available on HBO Max.