The Cassini-Huygens Mission: Orbiter Remote Sensing Investigations

At this writing the Cassini spacecraft has fired its engine and successfully inserted itself and its precious cargo of scientific instruments into orbit, the first step of its exploration of the Saturnian system. The suspense is not over, however. While exciting images of the rings have been captured, an exotic composition of Phoebe sensed by the mapping spectrometer and unexpected panoply of magnetic waves and plasma dynamics encountered on the incoming trajectory and initial orbit, the HuygensprobeisstillonboardandthefirstcloseflybyofTitanhasnottakenplace. Not until Christmas Day will the probe be released. Navigators are still checking their calculations, worrying about known unknowns like the mass of Saturn’s moons that could cause ever so small a deviation from the planned trajectory of the probe. The orbiter investigators are also anxious but they get their taste of Titan earlier, on October 26. How well will they detect the surface? How thick is the atmosphere? Does Titan have a magnetic field? Is there lightning in the atmosphere of Titan? While terrestrial and Hubble Space Telescope pictures have improved greatly over the years, they cannot match the resolution obtainable from orbit about the planet, and much of the data is simply unobtainable without direct in situ sensing. olume 1 of this three volume set described the Cassini/Huygens mission, its V V scientific objectives and the Huygens probe that will soon enter the Titan atmosphere. Volume 2 described the in situ investigations on the orbiter. In this, the third and final volume of the compendium, we describe the remote sensing inves- tigations: radio science, radar, visible and infrared spectroscopy, thermal infrared studies, ultraviolet spectroscopy and visible imagery. This volume completes our description of this most ambitious mission. For the editor, this has been a very ambitious task, extending over an eight-year period. We trust that the reader will find these pages beneficial, gaining insight into the how and why of the Cassini investigations and allowing the broader scientific community to share in the advance in our understanding that the mission brings. As with Volumes 1 and 2, this volume is due to the efforts of many individuals especially the referees and authors who have helped produce a very readable and complete descriptions of the investigations. We especially wish to thank Anne Mc Glynn who assisted in the initial stage of the assembly of this collection and Marjorie Sowmendran who completed the effort upon Anne’s retirement. Lastly, none of this would have been possible without the years of labor by the women and men of the Cassini/Huygens project who built the spacecraft, tested it, programmed the software, and navigated and operated the spacecraft so flawlessly.