New Horizons (Pluto)

Launched on 19 January 2006, New Horizons completed the first-ever flyby of Pluto on 14 July 2015, travelling 4.67 billion miles in nine and a half years. The images it returned demolished assumptions about the dwarf planet: Pluto had towering water-ice mountains, nitrogen glaciers flowing into smooth plains, and a vast heart-shaped basin named Tombaugh Regio — a geologically active world far stranger and more dynamic than anyone had predicted.