Voyager Probes

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.

As of 2021, the two Voyagers are still in operation past the outer boundary of the heliosphere in interstellar space. They both continue to collect and transmit useful data to Earth.