Challenger crew members Bruce McCandless II and Robert Stewart made the first free spacewalks in 1984, using a jetpack-like device called the manned maneuvering unit. Though no longer in use, these units allowed astronauts greater freedom and maneuverability, freeing them from being tethered to the shuttle. In 1985, the crew used the manned maneuvering unit to repair a malfunctioning satellite, at a cost of $50 million. This was a bargain, considering replacing the satellite would have cost about $250 million.
NASA