After five long years of interplanetary travel, Cassini has finally sighted the ringed planet looking distant, mysterious, and serene. The spacecraft has crossed more than half the distance to Saturn from Jupiter, its last rendezvous. Sunlight has dimmed to twilight and temperatures have fallen to about 300 degrees below zero Fahrenheit. Only four other spacecraft have come this far before, and the last, Voyager 2, did so 22 years ago. The realm of the outer planets is neither for the timid nor the impatient.
All spacecraft subsystems are functioning smoothly, and the onboard cameras have captured a set of images that have been composited to form a color rendition of Saturn (Imaging Diary: Beyond Jupiter). It is too early to see the familiar sights of so long ago: the clouds and eddies in the hazy atmosphere, the F ring and its small shepherd moons, the spoke-like markings and countless grooves in the rings. But the banded nature of the planet is apparent, and the high elevation of the sun and Cassini's approach from the southern hemisphere create a dramatically different specter than that of Voyager. At 5.2 km/sec, Cassini is fast approaching the planet, and before too long, we will enjoy the rewards of years' worth of planning.
Early 2004 will see the initial routine collection of images on the atmosphere and rings; searches for previously unseen satellites both within and exterior to the rings; our closest and only encounter with the small moon Phoebe, believed to be a captured asteroid, in mid-June; a movie of the murky Titan atmosphere starting in late May; and finally insertion into Saturn orbit on July 1, 2004.
In the meantime, the ringed planet beckons ... and waits.
Carolyn Porco Cassini Imaging Team Leader CICLOPS/Space Science Institute Boulder, CO