Forty years and still going strong
Launched in 1977, the unmanned space probes Voyager 1 and 2 carried out an extensive survey of the planets and moons of the outer solar system. Visiting Jupiter, Saturn, Uranus, and Neptune, the Voyager program can only be called an unqualified success on virtually every level. The twin spacecraft returned thousands of photographs and reams of scientific data that fundamentally changed our understanding of our entire solar system. Currently in interstellar space, Voyager 1 is the farthest man-made object from Earth. Voyager 2 is near the edge of our solar system and will one day also enter interstellar space.