ESA has published a photo (ESA/DLR/FU Berlin (CC BY-SA 3.0 IGO)) of the Arcadia Planitia region on Mars captured by its Mars Express space probe’s High Resolution Stereo Camera (HRSC). This is an interesting region from a geological point of view because it’s northwest of the large volcanoes of Tharsis, the largest in the entire solar system, and traces of ancient lava flows are still visible. It could be important for the exploration of the red planet if confirmation of the presence of frozen water right under the surface were to arrive.
Arcadia Planitia is a rather flat Martian plain marked by lava flows that are estimated to be up to three billion years old. It’s not uniform, and the image shows how the area on the right and at the bottom is rougher, has a different color, and more craters, including the decidedly largest one, which has a diameter of about 15 kilometers. The atmosphere of Mars is very thin, yet the wind manages to lift and transport particles that generate a light haze that makes the image appear a bit blurry.
Sometimes, the strong temperature difference between day and night causes the winds to generate dust devils in Arcadia Planitia similar to those that can be seen in Earth’s deserts. In the image, four small dust devils are moving, leaving bright trails and shadows with pink hues.
Dust devils are not the only similarity between Mars and Earth’s deserts. In the upper part of the image, there are rock formations of the type called yardangs, ridges produced by wind erosion in desert environments.
ESA and other agencies are interested in the presence of water in the subsurface of Mars. An article published in the “Journal of Geophysical Research: Planets” offers evidence of the presence of water ice under the surface of an area on the border between Arcadia Planitia and the northern part of Amazonas Planitia. A team of researchers led by Erica Luzzi, a planetary geologist and researcher at the Mississippi Mineral Resources Institute, conducted a geomorphological analysis that confirms previous studies’ indications of the presence of water ice.
The 15-kilometer-diameter crater is surrounded by layered structures of material that provide further indications of the ice that was present underground when the impact formed it. The state of the crater indicates that the impact occurred recently, from a geological point of view.
All of that makes Arcadia Planitia a candidate for possible Mars lander and rover missions, which could access the water ice with instruments that can access a limited depth. Plans for human missions are still purely theoretical, but if they ever get developed, Arcadia Planitia would be a candidate for the first human outpost on Mars.
