When was the first spacecraft to orbit another planet launched?

NASA’s Mariner 9 launched on 30 May 1971 and entered orbit around Mars on 14 November 1971. It was the first spacecraft to orbit another planet and the first to map the Martian surface globally. When it arrived, a planet-wide dust storm was already raging, so the mission had to wait until the atmosphere cleared. Mariner 9 eventually returned thousands of images and transformed scientific understanding of Mars, revealing volcanoes, canyons, and ancient river channels.