“Like its predecessor, the Viking 2 mission consisted of a lander and an orbiter designed to take high-resolution images, and study the Martian surface and atmosphere. Both the Viking 1 and 2 landers benefited greatly from their orbiting counterparts, which snapped images that helped mission controllers navigate the landers to safe landing sites.”
This particular image was taken by the Viking 2 Orbiter and shows a massive dust storm on the red planet. This spectacular storm can be seen on a global scale. The Viking 2 mission would end 3 years later on April 11, 1980.