Dust Storms
A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions.
In 1971-72, Mariner 9 photographed ~80% of Mars’ surface from orbit, revealing ancient river beds, craters, extinct volcanoes, canyons, layered polar deposits, wind-driven sediments, weather fronts, ice clouds, dust storms & fogs. It renewed hope of past life on Mars. It’s still orbiting Mars today.