BOULDER, Colo. -- Hours after entering orbit around Saturn, the Cassini-Huygens spacecraft began relaying images of the planet and its rings that were so spectacular they stunned even the scientists who knew more than anyone what to expect.

"The beauty and clarity of these images ... they are shocking to me," said Carolyn Porco, Cassini imaging team leader from the Space Science Institute in Boulder, Colo. "We are seeing structure, literally, that we've never imaged before," she added.

As the raw, unprocessed images from Cassini began to reach mission control at the Jet Propulsion Laboratory in Pasadena, Calif., the close-up photos of Saturn's ring system began revealing exciting, never-before-seen features, Porco said.

"They are just beautiful. They are very sharp," Porco said. "We're going to have a field day with these. ... This is an amazing opportunity to be this close to the rings. And we'll never be this close to the rings again ... this is a first."

The international $3.3 billion mission completed its 96-minute Saturn Orbit Insertion rocket burn at roughly 12:12 a.m. Eastern Daylight Time, early Thursday morning. The successful maneuver sparked applause, handshakes and hugs from flight controllers at JPL.

In reaching its initial orbit, Cassini started an initial four-year odyssey of the giant planet, its majestic rings and family of moons.

Density waves

Porco said density waves in the rings appear to have been captured in the initial images. A density wave is caused by a small moon that yields a gravitational perturbation on the ring particles. Those particles then array themselves in a very coherent fashion, making a wave through the rings.

"This looks like it could be that," Porco added. "I'm proud to say that I took these pictures ... these are just remarkable."

Porco said that there is already a push by scientists to return to Saturn with a mission that would actually hover above the rings and view how Saturn's mostly icy ring particles interact.

At a press briefing at the Jet Propulsion Laboratory July 1, scientists reiterated that they were seeing phenomena never before imaged, captured in the first batch of 61 Cassini photos.

"This is not animation ... this is not power point," said Edward Weiler, NASA associate administrator for Space Science. "The studies we're doing at Saturn go well beyond the understanding of ring systems. It could tell us a lot about how planets form around other stars."

Porco said scientists believe they saw in Saturn's rings some of the processes that went on in the solar nebula before the planets formed. "In fact, we may be seeing some of the processes that actually aided the development of the planets," she said.

The images included the first close-up pictures of what the scientists described as "ringscapes," along with small sheparding moons.

In one striking blowup, Porco pointed out what almost looks like straw, clumps of material within Saturn's A Ring. "I don't know what this is ... I literally don't have a clue."

Porco said that pictures to be taken by Cassini during the next four years will be roughly 300,000 in number, equaling about 100 a day, sometimes more, sometimes less.

Robert Mitchell, Cassini program manager said that a status-check on the Cassini spacecraft after maneuvering into orbit shows the machine is in excellent shape.

"There was not a single red alarm. Not a single indication of any fault activity and no subsystem had any anomalies," Mitchell said. "So the spacecraft status is that it's just perfect."

Mitchell said Cassini was right on target entering Saturn orbit. A decision is forthcoming whether or not a trajectory clean-up maneuver, set for the weekend, will be needed.

"The navigation status is excellent. We couldn't have asked for anything better than what we've got," Mitchell added.

The Cassini mission will face another dramatic challenge in December, when the spacecraft will release the piggybacked Huygens probe -- provided by the European Space Agency -- which will plummet through the hazy atmosphere of Saturn's largest moon, Titan.

Shortly after Cassini began orbiting Saturn, David Southwood, director of scientific programs for the European Space Agency noted: "This was America's night. This was NASA doing it right," he said.

"They really gave those of us in Europe a challenge. We've got six months to go until we land on Titan. We're just praying that everything will go as well."