Mariner 9 views of shield volcano
A Martian shield volcano, approximately 25 miles across at the crater, photographed consecutively by Mariner 9 with the wide-angle and telephoto lenses. The summit crater and grooves down the flank probably were produced by subsidence flowing subsurface movement of magma.
Mariner 9 was the first spacecraft to orbit another planet. The spacecraft was designed to continue the atmospheric studies begun by Mariners 6 and 7, and to map over 70% of the Martian surface from the lowest altitude (1500 kilometers [900 miles])and at the highest resolutions (1 kilometer per pixel to 100 meters per pixel) of any previous Mars mission
Date: November 14, 1971