Lord Of The Rings

Saturn has been ready for its close-up for a long time. On June 30 the planet is going to get it as the $1.4 billion Cassini-Huygens spacecraft, after a journey of 2.2 billion miles, fires its retrorockets and puts itself into Saturnian orbit.

It's the start of a four-year tour, during which the ship will make at least 76 loops of the planet and engage a dozen cameras and instruments. NASA will be able to tweak the trajectory of the orbiter so it can slalom among nine of Saturn's 31 moons. The grandest of the satellites is Titan, which has long frustrated scientists because its dense atmosphere, laced with organic gases, obscures its surface.

The spacecraft will penetrate that atmosphere with radar and a free-flying 705-lb. conical probe (the Huygens half of the Cassini-Huygens tandem), scheduled to plunge into the Titanian skies on Jan. 14, 2005. Huygens will make a 2 1/2-hr. parachute descent, transmitting data all the way. When it touches down, having made the most distant landing ever by an earthly probe, it is expected to survive for no more than half an hour. Cassini, designed to live much longer, should be beaming back data until 2008.