Cassini spacecraft goes into orbit around Saturn

International probe carries out complicated maneuver through rings

July 01, 2004|By Thomas H. Maugh II and Eric D. Tytell | Thomas H. Maugh II and Eric D. Tytell,LOS ANGELES TIMES

PASADENA, Calif. - NASA's Cassini spacecraft successfully fired its rocket motor yesterday evening, becoming the first spacecraft to orbit the ringed planet Saturn. Whoops of joy erupted and engineers hugged one another in the Jet Propulsion Laboratory control room here as the craft beamed back word that it had successfully completed the perilous maneuver.

"We have burn complete," mission communicator Todd Barber said to cheers and high-fives. "Welcome to Saturn."

For a tense 96 minutes, engineers had listened to the Doppler change in a tiny radio signal from Cassini indicating that its rocket was firing and slowing the craft, which had taken seven years to complete its 2.2 billion-mile journey to Saturn.

The signal finally stabilized, on schedule, at 9:12 p.m., a sign that the rocket had fired for its full allotted time, slowing the craft just enough for it to be captured by the gravity of the massive planet.

Cheers and handshakes erupted again minutes later, at 9:30 p.m., when Cassini pointed its large antenna toward Earth and sent back a "blast of data" indicating that all was well, Barber said. The craft then turned its antenna away once more as it snapped a hurried series of photographs of Saturn's rings during its closest approach to them.

Yesterday had been a day of anxiety and anticipation as the craft neared the largely gaseous planet. Engineers had sent their last commands to Cassini Tuesday and could only "chew their nails" as the craft got closer to the "hair-graying" maneuvers of entry, program manager Robert Mitchell said.

The craft had to operate on its own because, with Saturn 900 million miles from Earth, radio signals take 83 minutes to reach it.

At 7:11 p.m. yesterday, the craft hurtled through the gap between Saturn's F and G rings at a speed of 27,000 mph. About 15 minutes later, the craft began its 96-minute burn.

Cassini is scheduled to spend four years orbiting Saturn, making at least 76 orbits, visiting its largest moon, Titan, 42 times and flying by several of the planet's other 30 known moons. The craft could continue orbiting the planet for as long as 15 years.

On Christmas Eve, Cassini will release the Huygens probe, which will plunge to the surface of Titan three weeks later. Scientists are particularly excited about that probe because Titan is the only moon in the solar system known to possess a dense atmosphere.

The project is co-funded by the National Aeronautics and Space Administration, the European Space Agency and the Italian Space Agency.

The Los Angeles Times is a Tribune Publishing newspaper.

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