The Outer Limits - The Man who was Never Born (1963)
The Man who was Never Born was the 6th episode of the first season of The Outer Limits.
An astronaut returning to Earth finds himself flung into the distant future of 2148, where he meets the last mutated remnants of humanity living alone on a ruined Earth.
In an attempt to prevent this future from happening, spaceman Reardon takes Andro the mutant with him, returning through the time rift intent on altering history.From there on it all goes a bit pear-shaped before coming good at the very end but with a cost that’s somewhat spelled out in the story's title.
Note the design of the helmet and suit then keep watching