Voyager 1 Encounters Saturn

by United States. National Aeronautics and Space Administration

SATURN ENCOUNTER

Voyager 1 approached within 124,000 kilometers (77,000 miles) of Saturn’s cloudtops. Six of the satellites that were photographed are shown in their approximate positions at closest approach by the spacecraft.

TITAN DIONE TETHYS MIMAS ENCELADUS RHEA

Voyager 1’s Saturn encounter period began on August 22, 1980, at a range of 109 million kilometers (68 million miles) from the planet. Even at this great distance, Voyager’s images were better than any from Earth-based telescopes. During the long encounter period, which extended through December 19, 1980, continuous observations of Saturn’s realm were carried out by Voyager’s instruments. Voyager 1’s flight path through the Saturn system demanded navigation of the highest precision to meet three critical targets: (1) a close 4000-kilometer (2300-mile) flyby and occultation at Titan, (2) a precise, three-minute time period when the spacecraft was emerging from occultation at the same time Earth was in a position to receive the spacecraft signals passing through the gap between Saturn and its rings, and (3) a flight path through the E-Ring at Dione’s orbit to assure safe passage through a zone clear of potentially dangerous material. To assure these targets were achieved, small trajectory trim maneuvers were executed on October 11, 1980, and again on November 6, 1980, as Voyager 1 sped toward Saturn.

Voyager spacecraft and scientific instruments.

HIGH-GAIN ANTENNA (3.7-meter diameter) LOW-ENERGY CHARGED PARTICLE COSMIC RAY PLASMA IMAGING ULTRAVIOLET SPECTROMETER INFRARED INTERFEROMETER SPECTROMETER PHOTOPOLARIMETER OPTICAL CALIBRATION TARGET PLANETARY RADIO ASTRONOMY AND PLASMA WAVE ANTENNA (2) RADIOISOTOPE THERMOELECTRIC GENERATOR (3) MAGNETOMETER BOOM

By October 24, 1980, when Voyager 1 was about 30 million kilometers (19 million miles) from Saturn, the spacecraft’s narrow-angle camera could no longer capture the planet in a single picture. Thus, a period of multiple images or mosaics began. By November 2, 1980, even four-picture mosaics could no longer cover the rapidly growing scene. Voyager 1’s pace of operations reached an exciting peak during the near-encounter phase from November 11 through November 13, 1980. While still about 1.6 million kilometers (1 million miles) from closest approach to Saturn, Voyager 1 encountered Titan on November 11, 1980, and then dipped below the ring plane as it accelerated rapidly toward Saturn. On November 12, 1980, Voyager 1 came within 124,000 kilometers (77,000 miles) of the cloudtops of Saturn’s southern hemisphere, where Saturn’s gravity altered the spacecraft’s course, hurtling the spacecraft upward past the ring plane. Close observation of Saturn’s other major satellites and its rings were made during this passage.

From Earth to Saturn, Voyager 1 has traveled in the ecliptic plane, the plane in which the major planets orbit. Now, having completed its final planetary flyby, Voyager 1 is rising above this plane on a trajectory that will eventually carry it above and out of the solar system, probably before the end of this century. As it proceeds, the spacecraft will return information about the solar wind and magnetic fields in the far, unexplored reaches of our solar system and will observe cosmic rays emitted from the distant stars among which Voyager will ultimately cruise.