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.

                                2025 July 15
       [2]A view of the surface of Mars shows an unusual feature -- a
       seemingly square crater bounded on three sides. Please see the
                 explanation for more detailed information.

                      Collapse in Hebes Chasma on Mars
    Image Credit & [3]License: [4]ESA/[5]DLR/[6]FU Berlin ([7]G. Neukum)

   Explanation: What's happened in Hebes Chasma on Mars? Hebes Chasma is a
   depression just north of the enormous [8]Valles Marineris canyon. Since
   the depression is unconnected to other surface features, it is
   [9]unclear where the internal material went. Inside [10]Hebes Chasma is
   [11]Hebes Mensa, a 5 kilometer high mesa that appears to have undergone
   an unusual partial collapse -- a collapse that might be providing
   clues. The [12]featured image, taken by ESA's robotic [13]Mars Express
   spacecraft currently orbiting [14]Mars, shows great details of the
   chasm and the unusual [15]horseshoe shaped indentation in the central
   mesa. Material from the mesa appears to have flowed onto the floor of
   [16]the chasm, while a possible dark layer appears to have pooled like
   ink on a downslope landing. One [17]hypothesis holds that salty rock
   composes some lower layers in [18]Hebes Chasma, with the salt
   dissolving in melted ice flows that drained through holes into an
   underground [19]aquifer.

                   Tomorrow's picture: unicorn space rose
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    Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell
                                 ([34]UMCP)
          NASA Official: Amber Straughn [35]Specific rights apply.
            [36]NASA Web Privacy, [37]Accessibility, [38]Notices;
                A service of: [39]ASD at [40]NASA / [41]GSFC,
                         [42]NASA Science Activation
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2507/HebesChasma_esa_960.jpg
   3. https://creativecommons.org/licenses/by-sa/3.0/igo/
   4. http://www.esa.int/
   5. https://www.dlr.de/de/wr/
   6. http://www.fu-berlin.de/
   7. https://www.esa.int/Science_Exploration/Space_Science/People/Man_with_a_plan_An_interview_with_Gerhard_Neukum
   8. https://apod.nasa.gov/apod/ap241110.html
   9. http://1funny.com/wp-content/uploads/2011/02/confused-dog.jpg
  10. http://en.wikipedia.org/wiki/Hebes_Chasma
  11. http://www.uahirise.org/ESP_016818_1785
  12. http://www.esa.int/spaceinimages/Images/2013/10/Hebes_Chasma_mesa
  13. http://en.wikipedia.org/wiki/Mars_Express
  14. https://science.nasa.gov/mars/
  15. https://apod.nasa.gov/apod/ap170522.html
  16. http://www.esa.int/spaceinvideos/Videos/2013/06/Fly-through_movie_of_Hebes_Chasma
  17. http://geomorphology.sese.asu.edu/Papers/Adams_etal_hebes_chasma_salt_tectonics_geol.pdf
  18. https://www.google.com/mars/#lat=-1&lon=-76&zoom=8
  19. http://en.wikipedia.org/wiki/Aquafer
  20. https://apod.nasa.gov/apod/ap250714.html
  21. https://apod.nasa.gov/apod/archivepix.html
  22. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  23. https://apod.nasa.gov/apod/lib/aptree.html
  24. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  25. https://apod.nasa.gov/apod/calendar/allyears.html
  26. https://apod.com/feed.rss
  27. https://apod.nasa.gov/apod/lib/edlinks.html
  28. https://apod.nasa.gov/apod/lib/about_apod.html
  29. https://asterisk.apod.com/discuss_apod.php?date=250715
  30. https://apod.nasa.gov/apod/ap250716.html
  31. http://www.phy.mtu.edu/faculty/Nemiroff.html
  32. http://www.phy.mtu.edu/
  33. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  34. http://www.astro.umd.edu/
  35. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  36. https://www.nasa.gov/about/highlights/HP_Privacy.html
  37. https://www.nasa.gov/general/accessibility/
  38. https://www.nasa.gov/privacy/
  39. https://astrophysics.gsfc.nasa.gov/
  40. https://www.nasa.gov/
  41. https://www.nasa.gov/centers/goddard/
  42. https://science.nasa.gov/learners
  43. http://www.mtu.edu/