Click for original image.

Today’s cool image will be a mystery with the answer below the fold. Before you look at the answer, however, you must try to come up with your own explanation for the picture to the right, cropped to post here, that was taken on September 25, 2018 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

What we see in this picture is what looks like a striped terrain, alternating bands of light and dark. What caused the bands? Why the different colors?

The overview map above provides some clues. The white rectangle inside Juventae Chasma near the map’s center marks the area within which this picture was taken, though the picture to the right covers only about a pixel inside that rectangle.

Can you guess what these stripes reveal, from this little information? For this quiz to work you must make a guess, but be prepared to be wrong and quickly reassess your conclusions. Such is the real scientific method, so rarely taught now in schools.

The oblique image to the right comes from a global mosaic created from all of MRO’s context camera pictures, with the rectangle in the overview map above indicating the area covered. The picture above is only a tiny area of stripes on the western slope of this terraced 8,000-foot-high mountain. The stripes indicate different sedimentary layers, with the dark bands in between probably caused by trapped Martian dust.

The scientists call these sediments hydrated sulfates, which means the sulfur here has the molecule of water chemical bound within it. Or more precisely, atoms of hydrogen and oxygen in a 2:1 ratio, suggesting that these atoms were once bound in a water molecule but then got bound into the sulfur itself.

The many sedimentary layers suggest many repeated events that slowly covered the terrain, which subsequently were exposed when Juventae Chasma was created, likely by some underground sublimation process of that water/ice. As the ice/water sublimated away it created a void that eventually caused the ceiling to collapse. What was left was this gigantic 130-mile-wide pit, essentially a sinkhole.

These layers however are deep inside Juventae. Though the mountain is about 8,000 feet high, its peak still sits another 8,000 feet below the rim of Juventae, seen in the upper left. You can see what might be a hint of these same deep layers near the bottom of the main wall of the abyss to the north, but those lines might simply be flow pattern caused by wind/ice/water from the far past.

What I see here most of all is another example of the spectacular landscape that humans will find when they finally walk the surface of Mars. The views will be breath-taking, and will make the journey forever worthwhile.