MESSENGER

MESSENGER set out on a 7.9-billion-kilometre, six-and-a-half-year cruise to Mercury, using flybys of Earth, Venus twice, and Mercury three times to shed enough velocity to be captured by the planet on minimal propellant. It entered orbit on 18 March 2011, the first spacecraft ever to do so, and went on to map the entire surface before being deliberately crashed into Mercury in 2015.