Rank 72 documents Mariner 10 — the first spacecraft to visit Mercury and the mission that invented the planetary gravity-assist maneuver still used by Voyager, Cassini, and New Horizons. Launched 3 November 1973 aboard Atlas-Centaur, the 502.9 kg probe used a Venus flyby on 5 February 1974 to bend trajectory toward Mercury — a technique now standard but revolutionary then. Three Mercury flybys in 1974–75 mapped roughly 45% of the cratered airless surface at closest approach 327 km, revealing a Moon-like world with weak magnetic field signatures. TV cameras, magnetometer, and plasma instruments operated until final contact 24 March 1975. Bruce Murray's JPL leadership and Marcia Neugebauer's plasma science defined the mission's legacy. Wallimilist renders Mariner 10 above cratered Mercury with orbital arc, vertical MARINER 10 title, gravity-assist kicker, and MARINER PROGRAM patch exactly as the master PNG dictates — default palette, Mercury terminator, and curator copy on slingshot pioneer heritage.