"We survived the plane of the ring crossing between the F and G rings" at a speed of 70,000 kilometers per hour (43,500 miles per hour) a NASA official said prompting celebratory cheers from dozens of engineers at the Jet Propulsion Laboratory (JPL) here.

For 96 minutes, the probe's engines burned to bring its speed down enough to be captured by Saturn's gravitational field, which occurred at 9:12 pm California time (0412 GMT Thursday).

Eighteen minutes later, exactly on schedule, NASA received another signal from the probe's high-gain antenna indicating that all systems were operating normally and that it was ready to begin its four-year mission to explore Saturn.

"We are ready for the big science pay-off, starting now," said Cassini mission manager Robert Mitchell.

"It feels awfully good to be on orbit around the lord of the rings," siad JPL director Charles Elachi.

The orbiting maneuver ended a seven-year, 3.5 billion-kilometerbillion-mile)

voyage from the launch pad at Cape Canaveral, Florida, to explore the second-largest planet of the solar system.

During its orbit entry, the probe will fly closer to Saturn than it will at any other moment of its four-year mission to come, giving it the chance to study the planet from about 20,000 kilometers (12,000 miles) above its surface.

"The spacecraft couldn't have performed any better," said flight director Julie Webster.

The product of NASA, the European Space Agency and the Italian Space Agency working together, Cassini-Huygens is the first man-made object to orbit the ringed planet, the sixth from the Sun and second in size after Jupiter.

The craft is made up of a US-built orbiter (Cassini) and the European-built probe (Huygens). The US contribution was 2.6 billion dollars and the EU, 660 million. ISA supplied the probe's high-gain antenna which channels all communications with Earth.

"Seventeen countries are involved. It's the Earth going around Saturn," said NASA's assiciate administrator for space science Ed Weiler.

It is hoped that during the next four years the probe will make 76 orbits around Saturn and 52 close passes by seven of the 31 known moons.

The study of the largest of Saturn's moons, Titan, is at the heart of the mission. Cassini is due to pass through its neighborhood 45 times at a distance of 950 kilometers (590 miles) to capture a high-resolution map of its surface.

Then, on December 25, Cassini is scheduled to free the Huygens probe, which will head for Titan and become the first man-made probe to land on a natural satellite of a planet other than Earth.

On January 14 next year, 20 days after falling out of orbit, Hyygens is due to penetrate Titan's atmosphere, release its parachute, and begin two and a half hours of scientific observation, whose data will be transmitted to Cassini and relayed to Earth.

"The Saturn system represents an unsurpassed laboratory, where we can look for answers to many fundamental questions about the physics, chemistry and evolution of the planets and the conditions that give rise to life," said Ed Weiler, associate administrator for space science.

The planet and its system of rings may serve as a model for the study of gas rings and dust that circled our Sun during the formation of the planets of the Solar System. Details on the interaction between Saturn, its rings and moons could allow understanding of how each of the planets of the Solar System evolved.

The probe is named after Jean-Dominique Cassini, a Paris Observatory director from the 17th century who discovered several of Saturn's moons and detected space between its rings, and the 17th century Dutch astronomer Christian Huyguens, who first observed Saturn's rings.

SPACE.WIRE