It! The Terror from Beyond Space

It! The Terror from Beyond Space is a movie starring Marshall Thompson, Shirley Patterson, and Kim Spalding. The first manned expedition to Mars is decimated by an unknown life form which stows away on the rescue ship.
In 1973, the first manned expedition to Mars is marooned; by the time a rescue mission arrives, there is only one survivor: the leader, Col. Edward Carruthers, who appears to have murdered the others! According to Carruthers, an unknown life form killed his comrades during a sandstorm. But the skeptical rescuers little suspect that "it" has stowed away for the voyage back to Earth...