Saturn: Riddles of the Rings

Voyager is watching two small moons that seem to be playing tag as they race around Saturn in almost the same orbit. The trailing moon is traveling faster than the leader, and should catch up with the leader in January 1982. The two pre¬sumably have been playing this game for billions of years. Through what sleight of physics do they avoid colliding?

Voyager has also spotted three “shepherd moons.” Two of these moons orbit along the inner and outer edges of the F ring (pages 8¬9), which wreathes the three bright main rings like a ribbon. Using odd gravitational tricks, these moons herd back in bounds particles trying to escape the F ring.

sattellites on saturn

These F ring moons, along with a third lit¬tle moon just 800 kilometers outside the bright A ring, seem to be shepherding the en¬tire main ring system. These unimpressive chunks of ice apparently hold in place count¬less trillions of ring particles, spanning 63,000 kilometers.
AN AURA OF ASTONISHMENT per¬vades the Jet Propulsion Laboratory in Pasadena, California. Twenty months earlier this same Voyager had discovered so many marvels at Jupiter—a complex, storm-tossed atmosphere, a thin ring, volcanism on one moon, and evidence of ancient Earth-like crustal movements on another—that its Saturn encounter had threatened to be anticlimactic.saturn pics

“We were afraid Voyager’s Saturn en¬counter was going to be a bust,” one project scientist confides.

But Saturn is not a bust. The JPL press¬room teems with reporters—far more than came for the Jupiter encounter. This space mission has clearly excited the public. Why? For one thing, the flawless performance of this little-spacecraft-that-could is a national pride. Space exploration is something the United States is very good at.

Then again, the pictures coming across the monitors speak directly to the imagina¬tion. Not fiery, chaotic, and psychedelic like those of Jupiter, they look cool, ethereal, and from a distance orderly enough to have been drawn with a celestial compass.

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