Mars Express Images a Valley on Mars
It’s a great day in the solar system — there are telescopes aimed at Jupiter to follow the aftermath of the recent collision into the southern polar region; instruments are monitoring solar activity, Cassini continues to show us the wonders of the Saturn system, Mercury is still being mapped, the Moon is under heavy study, and the news and images from landers and mappers at Mars continues to flow our way. Now, if we just had PEOPLE on Mars! Well, when the first Marsnauts DO get there, they’ll have great images like this one from Mars Express to study.
Where is this place? It’s near one of the largest canyons on Mars — a giant rift called Ma’adim Vallis. This area lies between the Tharsis volcanic region of Tharsis (and its four large volcanoes) and the Hellas Planitia impact basin.
There’s quite a lot of interesting terrain here and a little planetary science interpretation tells an interesting story. The canyon itself is 20 kilometers wide and 2 kilometers deep. It begins in the southern highlands close to the a region called the “dichotomy boundary” that divides the cratered highlands on Mars and the nearby lowland plains. The canyon ends in Gusev crater, where the Spirit Rover is currently exploring.
The image you see here covers a region of Mars about the size of the island of Cyprus on Earth. There’s a sharp boundary is visible that divides dark material to the west and light material to the east. This probably the edge of a basaltic lava flow. Wrinkle ridges are clearly visible on the surface of the lava flow and they probably formed as the rock was compressed by tectonic action after the lava was laid down.
The crater in the north part of the image is about 20 kilometers across and seems to be partly filled with lava deposits that flowed in after the crater formed. The smaller crater at the southern edge of the larger crater must have formed later because it has an ejecta blanket that may have formed from material rich in water ice that was blasted out during the impact.
A 200-kilometer-long linear feature divides the image almost in half. This is probably a trough that formed when the Tharsis volcanic region was active. That activity caused the whole area to “lift up” — and that had to have created a lot of stress in the crust. The typical way that surface crusts deal with stress is to break into pieces. Hence, you get fracture zones, and the creation of troughs and other broken terrain like you see here.
Images like these are fascinating for a lot of reasons. First, they’re another world — one that we’re learning a LOT about as our robot explorers send back more images and data. Second, they’re from a world that we hope humans will visit very soon. Third, those regions look so very familiar because we see places like them on Earth — and we know how they formed on Earth, so that helps us understand how they work on Mars. Finally, they’re just darned cool! Not a very scientific-sounding reason, but hey — science IS cool. And so is studying other planets!
