The fun begins even before Cassini enters orbit. On June 11, the spacecraft will fly within 1,240 miles of Phoebe, one of the planet's most remote moons, for its first direct encounter with the Saturn system. When that happens, some 200 scientists around the world will be hovering over their computers, waiting for the first wave of data to hit their screens. (Get real-time mission updates at saturn.jpl.nasa.gov.)
"We really don't know what we're going to find," says Mitchell, voicing a sentiment shared throughout the Cassini team. Planetary scientists already know enough about the Moon and Mars to focus on very specific questions–such as whether Mars once had water on its surface–and send spacecraft designed to answer those individual questions. With Saturn, however, we're still at the reconnaissance stage. That's why NASA is sending a multipurpose spacecraft capable of painting a broad-brush picture of Saturn and its moons.