Mariner 10 . ... Mariner 10 was the seventh successful launch in the Mariner spacecraft series, and the first to use the gravitational pull of one planet ( Venus ) to reach another ( Mercury ). ... It measured 1.39 meters (4.56 feet) diagonally and 0.457 meters (1.5 feet) in depth. ... Views of Mariner 10 . ... Venus/Mercury Mission . ... Launched in November 1973, this mission provided new information about Mercury and Venus in the Mariner program's first dual-planet mission. ...