A massive, planet-encircling dust storm occurred on Mars during the summer of 2018, resulting in many images where the surface could not be seen due to the dust. This is a problem for HiRISE but also gives us an exciting opportunity to see how the dust storm changed the surface.
We acquired this image as the storm was just starting to end and shows a region of dark sand dunes. The surface is only barely visible. However, taking images like this will let us see the effects of the storm as soon as possible. Despite the murk, some surface features are visible.
The cutout shows a comparison between this image and ESP_044240_2000, which covered the same spot in 2016. The old image shows a dark sand dune with streaks where sand has slumped down the steep slope. The new image, despite the haze, shows a different pattern of streaks. Because the storm has coated everything with dust, these are probably new sand avalanches that occurred within the last few weeks. [More at link]