Martian ice sheets sublimating like peeling paint?
Click for original image.
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 19, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The features are described as “ribbed terrain” in the label. To my eye they more resemble flakes of peeling paint, most especially the mesas in the lower left. On the full image there are many more examples that resemble old paint peels, barely attached to the wall.
The white dot on the overview map above marks the location, deep inside the 2,000-mile-long strip in the northern mid-latitudes I dub glacier country, because everything seems covered by glacial features. This location is at 42 degrees north latitude, where plenty of near-surface ice features are found on Mars.
At first glance it looks like the top “paint-peel” layers to the south have been slowly sublimating away, leaving behind the smooth plain to the north. The problem is that this smooth area in the full image actually appears to be a glacial ice sheet of its own, filling all the low areas between mesas.
In other words, we are probably looking at layers and layers of ice sheets, each created during a different Martian climate cycle, caused by the wide swings of the planet’s rotational tilt, or obliquity.
The location is within Arabia Terra, the largest transitional zone on Mars between the northern lowland plains and the southern cratered highlands. Thus it sits above the glaciers that fill the lower regions of chaos to the north. What we have here is terrain that will eventually become chaos terrain, as the narrow faults and cracks are slowly widened into canyons by the cycles of glacial activity.
