II.

Exploration of the Saturnian System

Observed through a telescope, Saturn’s brightest rings are easily visible, whereas only under optimal conditions can the fainter outer rings be seen. Sensitive Earth-based telescopes have detected many satellites, and in the haze of Saturn's gaseous envelope, pale belts and zones parallel to the equator can be distinguished.

Several United States spacecraft have enormously increased knowledge of the Saturnian system. The Pioneer 11 (see Pioneer) probe flew by in September 1979, followed by Voyager 1 in November 1980 and Voyager 2 (see Voyager) in August 1981. These spacecraft carried cameras and instruments for analyzing the intensities and polarizations of radiation in the visible, ultraviolet, infrared, and radio portions of the electromagnetic spectrum (see Electromagnetic Radiation). The spacecraft were also equipped with instruments for studying magnetic fields and for detecting charged particles and interplanetary grains.

The National Aeronautics and Space Administration (NASA) launched an orbiter called the Cassini spacecraft toward Saturn in October 1997. It reached Saturn in July 2004 and began studying the planet and its moons. Cassini launched a probe (the Huygens probe) that descended to the surface of Saturn's moon Titan early in 2005. In 2006 NASA scientists reported that Cassini had detected geysers on Saturn’s moon Enceladus. Previously, Cassini had detected carbon molecules on the moon’s surface. The discovery was particularly significant because the existence of liquid water, heat, and carbon molecules represent the three ingredients essential for life.