Space travel:NASA Mariner program to explore Mercury; Venus and Mars; Between 1962 and 1973; 10 spacecrafts were launched.- Mariner 10. -(Spacecraft; built by Boeing; after launch on November 3; 1973; the spacecraft passed Venus on February 5; 1974 and Mercury for the first time on March 29; 1974; this was the first time that a spacecraft passed Mercury; the Mariner 10 was the first spacecraft to use the gravitation pull of one planet to reach another).Photo 2017 (Eric Long; Smithsonian Institution National Air and Space Museum).Inv. No.: A19830006000Washington; Nat. Air and Space Museum.