The Mariner Program was a 10-mission program conducted by the American space agency NASA in conjunction with Jet Propulsion Laboratory (JPL). The program launched a series of robotic interplanetary probes, from 1962 to 1973, designed to investigate Mars, Venus and Mercury. The program included a number of firsts, including the first planetary flyby, the first planetary orbiter, and the first gravity assist maneuver.
The mission of Mariner 10 was a great success and unique in many ways. It was the first spacecraft to use gravity assist to visit more than one planet, a technique now used regularly to visit multiple bodies in the solar system. It was the first spacecraft to take close-up photographs of Venus and the first to explore Mercury. In just over 500 days, on a journey of more than a billion kilometers, Mariner 10 visited Venus once and Mercury three times, returning 7,000 photographs and greatly expanding our understanding of both planets. It also photographed the Earth and Moon and studied Comet Kohoutek.