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                        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.

                              2021 February 16

         IFRAME: [2]https://www.youtube.com/embed/M4tdMR5HLtg?rel=0

                     Perseverance: Seven Minutes to Mars
                        Video Credit: [3]NASA, [4]JPL

   Explanation: How hard is it to land safely on Mars? So hard that many
   [5]more attempts have failed than succeeded. The next attempt will be
   on Thursday. The main problem is that the [6]Martian atmosphere is too
   thick to ignore -- or it will [7]melt your spacecraft. On the other
   hand, the atmosphere is too thin to rely on [8]parachutes -- or your
   spacecraft will crash land. Therefore, as outlined in the [9]featured
   video, the Perseverance lander will lose much of its high speed by
   deploying a huge parachute, but then switch to rockets, and finally,
   assuming everything goes right, culminate with a hovering [10]Sky Crane
   that will slowly lower the [11]car-sized Perseverance rover to the
   surface with ropes. It may sound crazy, but the [12]Curiosity rover was
   [13]placed on Mars using a similar method in 2012. From atmospheric
   entry to surface touch-down takes about seven minutes, all coordinated
   by an onboard computer because [14]Mars is too far away for rapid
   interactive communication. During this time, [15]humans on [16]Earth
   will [17]simply wait to hear if the landing was successful. Last week,
   [18]UAE's [19]Hope spacecraft successfully began orbiting Mars,
   followed a day later by the [20]Chinese [21]Tianwen-1 mission, which
   will likely schedule a landing of its own rover sometime in the next
   few months.

                    News: [22]NASA Perseverance Coverage
                 Tomorrow's picture: light pillar with flare
     __________________________________________________________________

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     __________________________________________________________________

    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Phillip Newman [38]Specific rights apply.
              [39]NASA Web Privacy Policy and Important Notices
                A service of: [40]ASD at [41]NASA / [42]GSFC
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://www.youtube.com/embed/M4tdMR5HLtg?rel=0
   3. https://www.nasa.gov/
   4. http://www.jpl.nasa.gov/
   5. https://mars.nasa.gov/mars-exploration/missions/historical-log/
   6. https://en.wikipedia.org/wiki/Atmosphere_of_Mars
   7. https://youtu.be/lSoWxG30rb0
   8. https://youtu.be/Qg6xxRZWnI4
   9. https://youtu.be/M4tdMR5HLtg
  10. https://www.planetary.org/space-images/curiositys-skycrane-maneuver
  11. https://mars.nasa.gov/mars2020/spacecraft/rover/
  12. https://apod.nasa.gov/apod/ap191029.html
  13. https://apod.nasa.gov/apod/ap120731.html
  14. https://solarsystem.nasa.gov/planets/mars/in-depth/
  15. https://apod.nasa.gov/apod/ap190818.html
  16. https://apod.nasa.gov/apod/ap190825.html
  17. https://www.pdsa.org.uk/media/7845/kitten-hiding-page-image.jpg
  18. https://en.wikipedia.org/wiki/United_Arab_Emirates
  19. https://en.wikipedia.org/wiki/Emirates_Mars_Mission
  20. https://en.wikipedia.org/wiki/China
  21. https://en.wikipedia.org/wiki/Tianwen-1
  22. https://mars.nasa.gov/mars2020/timeline/landing/watch-online/
  23. https://apod.nasa.gov/apod/ap210215.html
  24. https://apod.nasa.gov/apod/archivepix.html
  25. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  26. https://apod.nasa.gov/apod/lib/aptree.html
  27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  28. https://apod.nasa.gov/apod/calendar/allyears.html
  29. https://apod.nasa.gov/apod.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. http://asterisk.apod.com/discuss_apod.php?date=210216
  33. https://apod.nasa.gov/apod/ap210217.html
  34. http://www.phy.mtu.edu/faculty/Nemiroff.html
  35. http://www.phy.mtu.edu/
  36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  37. http://www.astro.umd.edu/
  38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  39. https://www.nasa.gov/about/highlights/HP_Privacy.html
  40. https://astrophysics.gsfc.nasa.gov/
  41. https://www.nasa.gov/
  42. https://www.nasa.gov/centers/goddard/
  43. http://www.mtu.edu/