Mariner 10

Mariner 10 flight spare, National Air and Space Museum The long boom carries magnetometers well away from the electronics, and the two solar panels stick out like oars. Mariner 10 launched in November 1973, swung past Venus in February 1974 and used that planet's gravity to reach Mercury, the first time a spacecraft borrowed one world's pull to get to another. It flew past Mercury three times and was the first probe to visit the innermost planet.