thumb|250px|A poster of the planets and moons visited during the Voyager program.
The Voyager program is an American scientific program that employs two interstellar probes, Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment to explore the two gas giants Jupiter and Saturn and potentially also the ice giants, Uranus and Neptune—to fly near them while collecting data for transmission back to Earth. After Voyager 1 successfully completed its flyby of Saturn and its moon Titan, it was decided that Voyager 2 would continue on its pre-planned trajectory to fly by Uranus and Neptune.
After the planetary flybys were complete, decisions were made to keep the probes in operation to explore interstellar space and the outer regions of the Solar System. On 25 August 2012, data from Voyager 1 indicated that it had entered interstellar space. In August 2018, NASA confirmed, based on results by the New Horizons spacecraft, the existence of a "hydrogen wall" at the outer edges of the Solar System that was first detected in 1992 by the two Voyager spacecraft.
both Voyagers are still in operation beyond the outer boundary of the heliosphere in interstellar space. ,Voyager 1 was moving with a velocity of , or 17 km/s, (10.5 miles/second) relative to the Sun, and was from the Sun. At the same time, Voyager 2 was moving with a velocity of , or 15 km/s, relative to the Sun, and was from the Sun.]]