The
Voyager program is a continuing American scientific program that employs two
robotic probes,
Voyager 1 and
Voyager 2, to study the outer
Solar System. They were launched in 1977 to take advantage of a favorable alignment of
Jupiter,
Saturn,
Uranus, and
Neptune, and are now exploring the outer boundary of the
heliosphere. Although their original mission was to study only the planetary systems of Jupiter and Saturn, Voyager 2 continued on to Uranus and Neptune, and both Voyagers are now tasked with exploring
interstellar space. Their mission has been extended three times, and both probes continue to collect and relay useful scientific data.