When much of Mars was enshrouded by a recent massive dust storm, HiRISE captured this clear view of the surface because of the target’s unique location.
Olympus Mons is the biggest volcano in the Solar System, reaching a height of nearly 25 kilometers, almost 3 times taller than Mount Everest on Earth. This view of the western flank of Olympus Mons shows the surface at an elevation of 21.3 kilometers, far above the swirling dust clouds. In this picture, we can see details of the flows that erupted over millions of years to form the enormous shield volcano.
A similar situation unfolded in the early days of Mars exploration, when NASA’s Mariner 9 spacecraft reached orbit around Mars in 1971 and was soon joined by two Soviet space probes, Mars 2 and Mars 3. Mars was blanketed at the time by a global dust storm that persisted for months and completely obscured the surface of the planet. As the storm ended and the dust began to settle out of the atmosphere, the tops of the giant volcanoes were the first portions of the surface to be seen… [More at link]