September 21, 2021
Today in 1974, the Mariner 10 probe made its second flyby of the planet Mercury. Mariner 10 was the first spacecraft sent to study Mercury and the first mission to explore two planets (Mercury and Venus). More information about NASA’s Mariner 10 mission and its findings about Mercury may be found here.
Left: Mariner 10’s trajectory through the inner solar system (NASA). Right: Illustration of the Mariner 10 spacecraft (National Aeronautics and Space Administration via National Air and Space Museum, Smithsonian Institution)