                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2020 February 9

                            To Fly Free in Space
                         Image Credit: NASA, STS-41B

   Explanation: What would it be like to fly free in space? At about 100
   meters from the cargo bay of the space shuttle Challenger, Bruce
   McCandless II was living the dream -- floating farther out than anyone
   had ever been before. Guided by a Manned Maneuvering Unit (MMU),
   astronaut McCandless, pictured, was floating free in space. McCandless
   and fellow NASA astronaut Robert Stewart were the first to experience
   such an "untethered space walk" during Space Shuttle mission 41-B in
   1984. The MMU worked by shooting jets of nitrogen and was used to help
   deploy and retrieve satellites. With a mass over 140 kilograms, an MMU
   is heavy on Earth, but, like everything, is weightless when drifting in
   orbit. The MMU was later replaced with the SAFER backpack propulsion
   unit.

                     Tomorrow's picture: eclipsing camel
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.

