Cassini Sights Saturn
Saturn appears serene and majestic in the first color composite made of images taken by Cassini on its approach to the ringed planet, with arrival still 20 months away.
The planet was 285 million kilometres away from the spacecraft, nearly twice the distance between the Sun and Earth, when Cassini took a series of narrow angle images through various spectral filters as an engineering test on 21 October 2002. Three of those images have been color-composited to show the planet and its rings as they would appear to the eye through a ground-based telescope.
It is southern summer on Saturn. The Sun is a lofty 27 degrees below the equator and casts a semi-circular shadow of the planet partway across the rings, leaving the outer A ring in sunlight. The last Saturn-bound spacecraft, Voyager 2, arrived in early northern spring. None of the familiar features from the Voyager era, such as the spoke-like markings on the rings, clouds and eddies in the hazy atmosphere, and the ring-shepherding moons, are yet visible to Cassini.
Titan, Saturn's largest moon, appears in the upper left. About 5000 kilometres across, it is the only moon resolved from this distance. To increase visibility, its brightness has been enhanced threefold relative to the brightness of the planet. Titan is a major attraction for Cassini scientists who hope to study its haze-enshrouded atmosphere and peer down, with special instrumentation, to its surface. They will be looking for evidence of organic processes similar to those that might have occurred on the early Earth, prior to the emergence of life.
Cassini will enter orbit around Saturn on 1 July 2004. It will release a piggybacked probe, Huygens, which will descend through Titan's atmosphere on 14 January 2005.