Can you imagine floating in the vacuum of space with nothing anchoring you to the spacecraft? On Feb. 7, 1984, astronaut Bruce McCandless made history performing a spacewalk during STS-41B with no lifelines tethering him to space shuttle Challenger. Using the Manned Maneuvering Unit (MMU), McCandless and astronaut Bob Stewart completed separate untethered spacewalks during the mission, both venturing more than 300 feet/ 91 meters from Challenger.
Testing the MMU for the first time in space required a lot of focus and bravery, but McCandless and Stewart had faith in the hardware. Weighing 300 lbs. /136 kg, the MMU was powered by 24 small compressed nitrogen thrusters with two motion-controlled handles on either armrest for simple maneuvering. It was developed by engineer Charles Whitsett, and McCandless tested the MMU underwater and inside the Skylab space station prior to his famous spacewalk. Martin Marietta Aerospace produced the final version of the MMU used on STS-41B.
Be sure to stop by Space Shuttle Atlantis during your visit to see a replica of McCandless spacesuit and MMU floating near the Hubble Space Telescope!