Microwave Communications from the Outer Planets: The Voyager Project

During the late 1970s, there is a rare alignment of the outer planets which allows a single spacecraft to fly a multip1anet mission. The Voyager Project, which will fly two spacecraft past Jupiter and Saturn, is such a mission. In the late summer of 1977, two Voyager spacecraft were launched from the Air Force Eastern Test Range at Cape Kennedy, Florida. They each carried experiments to gather information about Jupiter, Saturn, their satellites and the interplanetary medium between Earth and Saturn. The Voyager science data rates varied from 80 bits/s to 115.2 kbits/s. The exceptionally high data rates, coupled together with the enormous Jupiter and Saturn distances and available spacecraft power, presented some unique problems to the communications system designers. This paper summarizes the Voyager Project, the mission objectives, and the spacecraft communications system required to meet the mission objectives. The complexities and problems, such as power consumption, weight, and antenna pointing constraints are presented, along with a detailed description of the radio frequency and S/X-band antenna subsystems.