This new image from ESA’s Mars Express orbiter shows bluish wind-blown deposits inside eroded craters in the Arabia Terra region of Mars.
This image was captured by the Mars Express orbiter on November 19, 2014. Image credit: ESA / DLR / FU Berlin.
Winds have long been known to be a factor in the Mars’ topography and climate. These winds can hit 60 mph (100 km/h), enough to create dust storms that cover much of the planet, lasting for many days or even weeks.
After such storms, it can be months before all of the dust settles. Just as on Earth, at certain latitudes, the winds tend to blow in certain directions.
As these winds travel they carve their surroundings, eroding and smoothing and gradually wearing away the Mars’ surface features over millions of years.
Evidence of these processes can be seen in the new image from the Mars Express’s High Resolution Stereo Camera.
The image shows part of the Arabia Terra region, which is scattered with craters of varying sizes and ages.
The craters in this image all show different degrees of erosion. Some still have defined outer rims and clear features within them, while others are much smoother and featureless, almost seeming to run into one another or merge with their surroundings.
The largest crater in this image also has the steepest rim. With a diameter of some 43 miles (70 km), this crater dominates the left, southern, side of the frame.
At first glance, the image seems to show something amazing in this crater, and in one of its neighbors to the right: is this a hint of blue liquid water? No, it is an optical illusion caused by the image processing.
The blue-hued patches lying within the ragged craters are actually dark sediments that have built up over time.
Again, this is due to the winds, which carry dark, volcanic, basalt-rich deposits across the Red Planet.
