Voyager program
The Voyager program is an ongoing American scientific program that employs two robotic Interstellar probes, "Voyager 1" and "Voyager 2". They were launched in 1977 to take advantage of a favorable alignment of Jupiter and Saturn, to fly near them while collecting data for transmission back to Earth. After launch the decision was taken to additionally send "Voyager 2" near Uranus and Neptune to collect data for transmission back to Earth.