When the Cassini spacecraft finally gets to Saturn next year, it will have some big shoes to fill -- its own. The robotic probe has snapped what's being billed as the best picture ever of Jupiter. While astronomers eagerly await Cassini's encore, expected to involve the most detailed exploration ever made of Saturn, mission managers are reveling in the new Jupiter photo, taken Dec. 29, 2000 and released today. "The imaging team wanted very much to take the ultimate picture of Jupiter," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colorado. "The one that...