Since their launch in 1977, the pair of Voyager spacecraft have explored the Jupiter (1979) and Saturn (1980 and 1981) systems. At Saturn, Voyager 1 turned southward, out of the plane of the ecliptic, but Voyager 2 continued to encounters with Uranus (1986) and Neptune (1989). Still operating continuously and transmitting data regularly, these spacecraft now probe the edge of the solar system.

Voyager 1 and Voyager 2 carried near-identical Ultraviolet Spectrometers (UVS) to study the composition, structure, and excitation of the upper atmospheres of the planets and their satellites. The spectrometers cover a spectral range of approximately 50 to 170 nm, in the extreme and far ultraviolet bands of the electromagnetic spectrum. The Voyager UVS instruments combine the capabilities for two very different kinds of observation in a single instrument. By emission spectroscopy, they measured airglow and auroral emissions from the atmospheres of the giant planets, several of their satellites, and the Io plasma torus. By occultation spectroscopy, they measured the absorption of sunlight and starlight by atmospheres to infer their composition and temperature profiles.

In addition to their planetary goals, the UVS instruments have been useful for probing the interplanetary medium and for astronomical observations.