﻿ Astronomy Picture of the Day [1]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 [2]See Explanation. Clicking on the picture will download the highest resolution version available. To Fly Free in Space Image Credit: [3]NASA, [4]STS-41B Explanation: What would it be like to fly free in space? At about 100 meters from the cargo bay of the [5]space shuttle Challenger, Bruce McCandless II was living the dream -- floating farther out than anyone had ever been before. Guided by a [6]Manned Maneuvering Unit (MMU), astronaut McCandless, [7]pictured, was [8]floating free in space. [9]McCandless and fellow [10]NASA astronaut [11]Robert Stewart were the first to [12]experience such an "un[13]tethered [14]space walk" during [15]Space Shuttle mission [16]41-B in [17]1984. The [18]MMU worked by shooting jets of [19]nitrogen and was used to help deploy and [20]retrieve satellites. With a mass over 140 kilograms, an [21]MMU is heavy on [22]Earth, but, like everything, is weightless when drifting in orbit. The MMU was later replaced with the [23]SAFER backpack propulsion unit. Tomorrow's picture: eclipsing camel __________________________________________________________________ [24]< | [25]Archive | [26]Submissions | [27]Index | [28]Search | [29]Calendar | [30]RSS | [31]Education | [32]About APOD | [33]Discuss | [34]> __________________________________________________________________ Authors & editors: [35]Robert Nemiroff ([36]MTU) & [37]Jerry Bonnell ([38]UMCP) NASA Official: Phillip Newman [39]Specific rights apply. [40]NASA Web Privacy Policy and Important Notices A service of: [41]ASD at [42]NASA / [43]GSFC & [44]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2002/freeflyer_nasa_3000.jpg 3. https://www.nasa.gov/ 4. https://www.nasa.gov/mission_pages/shuttle/shuttlemissions/archives/sts-41B.html 5. https://apod.nasa.gov/apod/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. https://www.nasa.gov/press-release/astronaut-bruce-mccandless-ii-dies-at-80 10. https://www.nasa.gov/astronauts 11. https://www.nasa.gov/sites/default/files/atoms/files/stewart_robert.pdf 12. http://www.youtube.com/watch?v=7K5DiKsZhTk 13. http://www-istp.gsfc.nasa.gov/Education/wtether.html 14. https://apod.nasa.gov/apod/ap990801.html 15. https://apod.nasa.gov/apod/ap990411.html 16. http://en.wikipedia.org/wiki/STS-41-B 17. https://en.wikipedia.org/wiki/Nineteen_Eighty-Four 18. https://www.youtube.com/watch?v=92ZRVlKuc0U 19. http://periodic.lanl.gov/7.shtml 20. https://apod.nasa.gov/apod/ap121209.html 21. http://en.wikipedia.org/wiki/Manned_Maneuvering_Unit 22. https://apod.nasa.gov/apod/ap070325.html 23. https://apod.nasa.gov/apod/ap011002.html 24. https://apod.nasa.gov/apod/ap200208.html 25. https://apod.nasa.gov/apod/archivepix.html 26. https://apod.nasa.gov/apod/lib/apsubmit2015.html 27. https://apod.nasa.gov/apod/lib/aptree.html 28. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 29. https://apod.nasa.gov/apod/calendar/allyears.html 30. https://apod.nasa.gov/apod.rss 31. https://apod.nasa.gov/apod/lib/edlinks.html 32. https://apod.nasa.gov/apod/lib/about_apod.html 33. http://asterisk.apod.com/discuss_apod.php?date=200209 34. https://apod.nasa.gov/apod/ap200210.html 35. http://www.phy.mtu.edu/faculty/Nemiroff.html 36. http://www.phy.mtu.edu/ 37. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 38. http://www.astro.umd.edu/ 39. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 40. https://www.nasa.gov/about/highlights/HP_Privacy.html 41. https://astrophysics.gsfc.nasa.gov/ 42. https://www.nasa.gov/ 43. https://www.nasa.gov/centers/goddard/ 44. http://www.mtu.edu/