A first rate little sci-fi story, told on a modest budget. Air Force office Marshall Thompson (star of 'It! The Terror from Beyond Space', and 'Fiend Without a Face') is the Earth-bound brother of an undisciplined test pilot who yearns to be be the 'first man into space'.
While testing a new rocket plane, the pilot kicks in all his reserve power and takes his ship right out of the atmosphere. Please note that this not a far-fetched idea in view of the fact that the X-15 had special attitude rockets along the fuselage to allow it to maneuver in the near vacuum of the upper atmosphere!
In space the pilot encounters a strange cloud of meteoric particles that smashes through his canopy and envelopes both his ship and his spacesuit-clad body in a flexible, asbestos-like coating. The material alters his physiology, changing him into creature that can survive in the low pressure of the upper atmosphere but NOT in the killing pressure at sea level.
He returns to Earth as a hideous monster (good makeup), gasping as his lungs struggled with the pressure that he's now unsuited for. In his dazed and desperate mental condition, the monster commits acts of violence, using the razor-sharp edges of his rough coating to slash his victims flesh.
While trying to track down the monster, Thomas and a scientist discuss the possibility of using the strange substance on the wreckage of the rocket plane as a heat shield for future space craft. Nice thinking, there.
All in all, a film with more to think about than to laugh at, unlike so many other low budget 1950s films.