Illustration depicting one of the two Voyager spacecraft. The dominant feature is the white high-gain dish antenna, used to communicate with Earth. Under this is a ring of electronics bays which surround a propellant tank. The boom at top right supports the imaging instruments (visible, ultraviolet and infra-red) and a plasma detector. At bottom left are the three cylindrical radio- isotope thermoelectric generators (RTGs) which provide electrical power. The latticed boom extending toward far left carries a magnetometer. The Voyagers explored the outer planets of the Solar System between 1978 and 1989, visiting Jupiter, Saturn, Uranus and Neptune.