                        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.

                                 2023 May 14
    An astronaut is seen hovering over the Earth. In the top part of the
     image, the astronaut is seen against the darkness of space. In the
    lower part of the image, the Earth is bright blue with white clouds.
          Please see the explanation for more detailed information.

                            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. During
   Space Shuttle mission 41-B in 1984, McCandless and fellow NASA
   astronaut Robert Stewart were the first to experience such an
   "untethered space walk". 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: red eagle
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

