Cassini's approach to Saturn has begun, and today the Imaging Team is marking the event with the release of a color composite of the ringed planet made from images taken on February 9, 2004. Since our last release, the planet has grown in size by 60%, new details in the atmosphere and rings are becoming visible, and scientists are already puzzling over the noticeable absence of the ghostly spoke-like dark markings in the rings first seen by Voyager on its approach to the planet 23 years ago. One thing is manifestly clear: there will be many more puzzles in store for us as the mission progresses.
From here on, the pace of image collection will be rapid and steady. During our initial approach, we will be taking near-daily, multi-wavelength images of the planet and its rings, and conducting searches for new moons between the rings and the orbit of the chaotically rotating moon, Hyperion. In April, when our camera's resolution is comparable to that seen from the Earth, we begin imaging hazy Titan in a variety of wavelengths to search for moving clouds high in its atmosphere and large-scale features on its surface.
On May 18, we officially enter the Saturn planetary system. On that day, the gravitational pull of Saturn begins to overtake the influence of the Sun and we cross the outer limits of the most distant group of Saturnian moons, only weakly bound to Saturn and located tens of millions of kilometers from the planet. A few days later, we commence a 3.5 week long campaign of Titan movie sequences to measure atmospheric winds and begin mapping its surface as Titan rotates. On June 11, we make a close, 2000-kilometer approach to Phoebe, collecting detailed images as we slip by. At 220 kilometers across, Phoebe is the largest of Saturn's outer moons and believed to be a captured asteroid.
By the fourth week in June, Cassini's velocity has increased dramatically and we begin falling swiftly into Saturn's gravitational well. And if we did nothing, we would just as swiftly escape out the other side. Instead, our seven year voyage will end when Cassini's main engine is fired, the spacecraft is slowed, and we enter Saturn orbit on July 1, 2004 UTC.
Feel free to ride along with us in this final leg of our journey and watch the drama unfold. To assist you in your travels, images we have collected along the way, a mere prelude to what will follow in the coming years, will be posted to this website -- weekly at first, and more frequently starting in late May. Each will be accompanied by the brief scientific musings and insights of the Imaging Team scientists who have planned the sequences that you are about to see.
After a long 13 year undertaking, and a 3.4 billion kilometer looping voyage across the solar system, it all begins today.