                APOD: 2017 December 31 - To Fly Free in Space

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                               2017 December 31
                                      [2]
                            To Fly Free in Space
                     Image Credit: STS-41B [3] , NASA [4]

Explanation: What would it be like to fly free in space? At about 100 meters
from the cargo bay of the space shuttle Challenger [5] , Bruce McCandless II
was living the dream -- floating farther out than anyone had ever been before.
Guided by a Manned Maneuvering Unit [6]  (MMU), astronaut McCandless, pictured
[7] , was floating free [8]  in space. McCandless [9]  and fellow NASA
astronaut [10] Robert Stewart [11]  were the first to experience [12]  such an
"un tether [13] ed space walk [14] " during Space Shuttle [15]  mission 41-B
[16]  in 1984 [17] . The MMU [18]  worked by shooting jets of nitrogen [19]
and was used to help deploy and retrieve satellites [20] . With a mass over
140 kilograms, an MMU [21]  is heavy on Earth [22] , but, like everything, is
weightless when drifting in orbit. The MMU was replaced with the SAFER [23]
backpack propulsion unit.

           Memorial: Astronaut Bruce McCandless II Dies at 80 [24]
                      Tomorrow's picture: sun ring [25]

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    Authors & editors: Robert Nemiroff [37] (MTU [38] ) & Jerry Bonnell [39]
                                  (UMCP [40] )
          NASA Official:  Phillip Newman Specific rights apply [41] .
              NASA Web Privacy Policy and Important Notices [42]
              A service of: ASD [43]  at NASA [44]  / GSFC [45]
                           & Michigan Tech. U. [46]
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Site notes:
  [1] archivepix.html
  [2] image/1712/freeflyer_nasa_3000.jpg
  [3]
https://www.nasa.gov/mission_pages/shuttle/shuttlemissions/archives/
sts-41B.html
  [4] https://www.nasa.gov/
  [5] ap950809.html
  [6] https://airandspace.si.edu/collection-objects/manned-maneuvering-unit-mmu
  [7]
https://www.nasa.gov/image-feature/nasa-celebrates-50-years-of-spacewalking
  [8] https://www.youtube.com/watch?v=RvnC--JjDBw
  [9] http://www.jsc.nasa.gov/Bios/htmlbios/mccandless-b.html
  [10] https://www.nasa.gov/astronauts
  [11] http://www.jsc.nasa.gov/Bios/htmlbios/stewart-rl.html
  [12] http://www.youtube.com/watch?v=7K5DiKsZhTk
  [13] http://www-istp.gsfc.nasa.gov/Education/wtether.html
  [14] ap990801.html
  [15] ap990411.html
  [16] http://en.wikipedia.org/wiki/STS-41-B
  [17] http://www.online-literature.com/orwell/1984/
  [18] https://www.youtube.com/watch?v=92ZRVlKuc0U
  [19] http://periodic.lanl.gov/7.shtml
  [20] ap121209.html
  [21] http://en.wikipedia.org/wiki/Manned_Maneuvering_Unit
  [22] ap070325.html
  [23] ap011002.html
  [24]
https://www.nasa.gov/press-release/astronaut-bruce-mccandless-ii-dies-at-80
  [25] ap180101.html
  [26] ap171230.html
  [27] archivepix.html
  [28] lib/apsubmit2015.html
  [29] lib/aptree.html
  [30] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [31] calendar/allyears.html
  [32] /apod.rss
  [33] lib/edlinks.html
  [34] lib/about_apod.html
  [35] http://asterisk.apod.com/discuss_apod.php?date=171231
  [36] ap180101.html
  [37] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [38] http://www.phy.mtu.edu/
  [39] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [40] http://www.astro.umd.edu/
  [41] lib/about_apod.html#srapply
  [42] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [43] https://astrophysics.gsfc.nasa.gov/
  [44] https://www.nasa.gov/
  [45] https://www.nasa.gov/centers/goddard/
  [46] http://www.mtu.edu/
