Cassini On Station

The Cassini-Huygens spacecraft (, Florida Today, NPR, (images & ESA), performed a flawless 96-minute engine burn Wednesday night and sailed into orbit around Saturn. During the next four years, Cassini will circle Saturn more than 75 times, conducting a detailed study of the planet and its moons and rings.

In January, the spacecraft’s Huygens probe will descend through the atmosphere of Titan, the largest moon of Saturn and a world high in astrobiological interest.

After two decades and $3.3 billion, the international exploration of Saturn begins this week after the spacecraft slipped through a gap in the planet’s shimmering rings and arcs into orbit.

Cassini is 22 feet long, 13.1 feet wide and weighed nearly 12,600 pounds loaded with fuel and the probe. Too far from the sun to rely on solar panels, it uses nuclear power to provide electricity.

Some people worried that an accident could release nuclear material protested Cassini’s Oct. 15, 1997, launch from Cape Canaveral, Fla. There was more concern when Cassini made a 1999 Earth flyby, but all went as planned.

The wok-shaped Huygens probe, developed by the European Space Agency, will be released from Cassini in December and will enter Titan’s atmosphere in January.

Just under 9 feet in diameter and weighing 705 pounds, its six instruments will investigate Titan’s atmosphere and then its surface, if it survives the impact of landing after a 2 1/2-hour descent by parachute.

It may not find a hard surface, however, and instead splash down into liquid ethane, which would quickly shut down the probe.

The probe will radio data back to Cassini up to a maximum of 30 minutes after touchdown. By then, either its batteries will have failed or Cassini will have passed over Titan’s horizon.

Saturn is some 930 million miles from Earth. Radio signals will take 84 minutes to travel each way, so the spacecraft will enter orbit on autopilot.

A 13-foot-diameter high-gain telecommunications antenna, was provided by the Italian space agency, Agenzia Spaziale Italiana, will serve as the Cassini spacecraft’s “voice box” and “ears,” sending data back and receiving commands from Earth during the 11-year-long mission. The multi-channel antenna is also a crucial part of several of Cassini’s scientific investigations, including imaging radar and gravity experiments.

Professor Tim Leighton, of Southampton University, says that discovering a sea on Titan would be a major contribution to the Huygens mission – with the sound of a splash or even a “methanefall” a way to do so, if it can be recognised.

He told BBC News Online: “If there is a splash and not a crunch when the probe lands, that would make Titan the first known body other than Earth to have an ocean open to an atmosphere.

“This would mean there could be babbling brooks and streams and a beach at minus 180C, lapped by an ocean of liquid cooking gas.

The Huygens Probe is named for 17th-century Dutch scientist Christiaan Huygens, who discovered Titan in 1659. The Cassini spacecraft is named for Italian-French astronomer Jean-Dominque Cassini, who discovered four more of Saturn’s moons and in 1675 found the gap — now called the Cassini Division — that separates two of Saturn’s more prominent rings.

Posted by Sam Churchill on .

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