The silver and black Voyager II spacecraft flew over the dazzling rings of Saturn Tuesday night after finding that the planet is circled by thousands of multicolored rings instead of the hundreds of rings seen by Voyager I nine months ago.
Flying at 54,000 mph no more than 2,000 miles from the edge of one of the majestic rings around the planet, the 1,800-pound Voyager II flew through the sunlit side of the rings shortly after midnight today and entered the dark side on the new leg of a journey that will take it to the planet Uranus in 1986.
While there was only a remote chance that the spacecraft would collide with the icy material that makes up Saturn's rings, flight controllers will not know until later this morning whether the spacecraft survived its journey through the rings.
Even at the speed of light, Voyager's signals took one hour and 26 minutes to travel the 1 billion miles to Earth.
Before sweeping through the rings, the spacecraft took photographs of them that were described as infinitely better than pictures taken of the same rings last November by Voyager I.
"Everywhere we look in the rings, we see more detail and more color than we saw before," said Dr. Jeff Cuzzi of the Ames Research Center in Mountain View, Calif. "We are delighted with the resolution of these photographs."
"We're that much closer this time, and we see literally thousands of rings around the planet," said Dr. Bradford C. Smith of the University of Arizona Tuesday at the Jet Propulsion Laboratory, where the flight of Voyager II is being directed. "Once again, we underestimated the scales we see when we fly closer to the outer planets."
"We are about 30 miles from our aiming point, not bad on a journey that has taken it more than 1.2 billion miles," Voyager program director Esker W. Davis said Tuesday. "Equally important, our time of arrival was off by only 2.7 seconds. We've threaded the eye of this needle perfectly."
Voyager's photographs of Saturn's rings showed striking differences in colors of the rings while fully illuminated by the sun. Photographs taken of the rings by Voyager I showed little color difference, mostly because Voyager I flew under the rings without the sun at its back to illuminate the rings fully.
One color picture released Tuesday showed inner rings composed of deep violets, purples and blues, while outer rings were different shades of yellow.
No two rings appeared alike, particularly the three largest inner rings. They were shaded in so many different blues and violets that they suggested that the rings formed when moons of different chemical elements broke up in Saturn's orbit just after the dawn of time.
"This is the solar system in which we live," Voyager project scientist Edward C. Stone said. "Every time we look at it, we learn new things about where we live."
Suggesting that many rings had different parents, the spectacular purples, blues and yellows of the rings provided one more piece of mounting evidence that Saturn's moons and rings have been in constant collision. The different colors of the three largest rings suggested that they were formed when three large moons collided eons ago to form at least three rings.
One scientist suggested that the rings may have so many colors because the trapped radiation that surrounds Saturn may rain on the rings in a way that it damages each ring differently.
"It could be that the thicker the ring, the more protection it has from radiation," Smith said. "The more radiation protection a ring has, the less it may be colored."
Besides taking spectacular pictures of the rings, Voyager II photographed a cyclone in the clouds above Saturn. "This is the first such storm we've seen form and disappear on another planet," said Dr. Garry Hunt of London's University College. "In a sense, this is a very historic event."
The cyclone was seen eight days ago in the shape of a question mark, then half of the number 6 and then the full number 6 just south of the jet stream that swirls around Saturn's equator at 1,100 mph.
By Monday, the cyclone began to break up, and by Tuesday night it was half its original size and was disappearing.
As it flew among the 17 known moons of Saturn, Voyager II took close-up photographs of three of the strangest moons in orbit around Saturn. Pictures of the moon Tethys showed a crater one-third Tethys' size, and scientists described it as the largest crater they have seen on any of the 17 moons.
"The crater is roughly 300 miles across," Smith said. "The central peak formed in the middle of the crater by whatever impact . . . formed the crater is higher than Mount Everest."
Photographs of the second outermost moon, Iapetus, showed a moon half black and half white, and suggested that the moon's dark side is being coated by the billions of dust particles in orbit around Saturn.
Measurements of the mass of Iapetus imply that it is 80 percent water ice, meaning that whatever is dusting and darkening the moon is not seeping from the moon's interior to form its black side.
"You can't have a rocky material coming from inside to make half this moon as black as the moon we see," London's Hunt said. "This moon is almost all ice. There is just not enough rock and dust inside it to make this black color."
Photographs of the moon Hyperion showed a a different shape each time a new or closer photograph was taken. In three pictures shown here today, Hyperion looked like a peanut, a prune and an arrowhead. Hyperion was measured at 200 miles wide and 140 miles long, certainly the oddest shape of any of Saturn's moons.
"How it got into that configuration is not known, although certainly the suggestion is that it was hit by another object and broken up . . . ," Smith said.