Saturn's Rings Still a Mystery

June 28, 2004 -- They've been described as a flamboyant hooped skirt, a jeweled necklace and a band of troops marching in a circle round the planet. Galileo Galilei, who discovered them, called them "ears."

Saturn's rings have inspired countless awe-filled descriptions, but they have also eluded scientific explanation.

A team of researchers from 17 different countries are now pinning their hopes on the six-ton, instrument-loaded Cassini spacecraft to duck into Saturn's orbit, peek into its rings and reveal their secrets. Cassini has already captured close views of Phoebe, Saturn's largest outer moon, and found it is covered by icy patches and very comet-like in nature. Scientists now expect to see greater detail of Saturn, its inner moons and mysterious rings once the craft maneuvers into a gap between two dust rings and enters Saturn's orbit on June 30.

Some of the questions they hope the craft may help them answer are what gives the rings their salmon hue? What's behind their strange waves? How old are they? And how long will they persist in Saturn's orbit?

"It will be like opening up a whole new world," said Linda Spilker, an expert on Saturn's rings and a project scientist for the joint NASA-European Cassini mission. "Things will go from fuzzy blobs to clear worlds."

Understanding what is contained in the rings and how and when they were formed could lead to understanding an even bigger picture — how the solar system formed. The ring of rocks and ice around Saturn represent a solar system in miniature, since scientists believe planets may have formed from similar cosmic debris.

Rings May Be Recent Feature

This is not the first time a spacecraft has visited Saturn's world. In the 1970s and early 1980s, earlier probes made fly-by's of the planet and returned some photos. But none came close in clarity to what Cassini's instruments promise.

"Instead of getting a crude spectrum," said Jeff Cuzzi, a planetary scientist at the NASA Ames Research Center, "We will be able to map the detailed shape of every bump and wiggle in the rings' spectrum."