Mariner 10, like all the Mariner spacecraft, was octagonal in shape and made of magnesium and aluminum. It was squat and long, measuring about 18 inches high and 4.5 feet in diameter. With its solar panels deployed -- flying toward the sun, it used solar power for electricity -- it measured a substantial 26 feet across. Its science payload was also fairly common for the Mariner family. Its suite of instruments included cameras, a magnetometer, a plasma science experiment, a charged particle telescope, an ultraviolet spectrometer and an infrared radiometer.
Mariner 10 launched on an Atlas Centaur rocket on Nov. 3, 1973. Not long after leaving the Earth, it turned around and looked back at our planet, snapping a stunning picture of our home planet and the moon together in one frame.