U22A-01 INVITED 10:20h
Cassini-Huygens in Orbit about Saturn
The Cassini-Huygens spacecraft was successfully placed in an orbit about Saturn on June 30, 2004. Starting with our approach to Saturn, the instruments carried by the Orbiter have been very active since early 2004. As a result, all of the Cassini Orbiter investigations have scientific rsults to report. The excitement of discovery started with the flyby of Phoebe, a distant satellite and Cassini-Huygens' first "contact" with the Saturnian system. Phoebe dazzled us with its morphology and variation of composition across its surface. Next, the spacecraft entered the agnetosphere at a time several days sooner than we expected. Close to three weeks after the Phoebe flyby, Cassini-Huygens passed through the rings,and fired its engine to place itself in orbit around Saturn. At that time a series of close-in observations were made that provided unique observations of the rings and of the planet magnetic field. The second ring passage followed hours later on the outbound leg of the trajectory. Within less than 30 hours after the second passage through the rings, Cassini-Huygens approached Titan to within 340,000 km. Distant observations of Titan gave us direct indication that Saturn's largest moon is much more complex than any other object that we have ever seen. The first low altitude flyby on October 26th gave Cassini scientists their first good look at Titan and its surface from an altitude of 1200 km. Results from this flyby will be discussed. A second low altitude flyby (2800 km altitude) of Titan occurs on 13th December. In the present paper we present an overview of the main mission events starting from Saturn approach until today. Highlights of the discoveries made so far are presented and placed in the context of what we know about the Saturnian system. The plans for the Huygens mission at Titan are also described. Cassini-Huygens is a joint NASA-ESA program in cooperation with ASI.
U22A-02 INVITED 10:40h
Saturn's Plasma Environment: First Surprises from Cassini
This talk will provide an overview of new physical insights about the plasma environment of Saturn and its giant moon Titan we gained from the initial phase of the Cassini/Huygens mission. This presentation will be given by the Interdisciplinary Scientists for Magnetosphere and Plasma Science of the Cassini/Huygens mission on behalf of the particles and fields science teams.
<a href='http://mapsview.engin.umich.edu/' >http://mapsview.engin.umich.edu/
U22A-03 INVITED 11:00h
Initial Cassini results on Saturn's Rings
In this talk we will review new Cassini discoveries concerning Saturn's rings and their associated small moons, and place them in the context of the state of current knowledge and current "big picture" questions. The highlighted results will start with approach, include the uniquely high resolution Saturn Orbit Insertion observations, and continue through the first periapse pass of October 2004. Discoveries by a number of Cassini teams will be covered. In addition, recent Earthbased observations of interest, and recent theoretical developments, will be mentioned. More details on these discoveries will be presented in the associated special session on Saturn's Rings (P07).
U22A-04 INVITED 11:20h
Saturn and its Atmosphere: First Results From Cassini
The talk will summarize the discoveries that pertain to the planet itself -- the composition and dynamics of its atmosphere and the nature of its magnetic and gravitational fields. I will review the results of remote sensing investigations covering the ultraviolet, visible, near infrared, far infrared, and microwave portions of the spectrum. I will also review the results of the magnetometer and plasma wave investigations, with emphasis on what they reveal about the rotation of Saturn's atmosphere and interior.
U22A-05 INVITED 11:40h
Titan
Titan's surface remains enigmatic after the T0 observations, in part because of the large distance of the Cassini spacecraft from Titan (the VIMS effective spatial resolution was no better than the latest ground-based Adaptive Optics observations), the high altitude scattering haze layer, and the surface's potential intrinsic complexity in composition and topography. The Ta observations of late October should have established, at some level, the extent to which Titan's surface is like that of other large icy satellites, or unique in being hydrocarbon-rich. Much of the seemingly self-contradictory nature of Titan's surface can be resolved by recognizing that large variations in composition and geology are likely over very small scales. I will focus on confronting new and traditional models with the data available, and forecast what might be in store as Cassini moves into its period of repeated close flybys of Titan. Ethane liquid, fogs and hazes, shiny polyacetylene deposits, and the role of ammonia in Titan's interior will all be considered in light of the new Cassini data expected this autumn.
U22A-06 INVITED 12:00h
Saturn's Icy Satellites: Observations From Cassini/Huygens
The so-called icy satellites of Saturn include all the orbiting objects in the system larger than a ring particle ($\sim$microns to meters) and smaller than Titan, which, with a density of 1880 kg m$^{-3}$, is an icy satellite also, but whose planet-scale size and massive atmosphere make it an object for special attention. Although the densities of the satellites are still subject to considerable uncertainty, most of the icy satellites are apparently more ice-rich than massive Titan, or the icy satellites of Jupiter. Some of the smallest, co-orbital and shepherd, satellites may be almost pure water ice in composition, in addition to having high porosities. Voyager images of the satellites revealed that most show evidence for internal activity and some degree of resurfacing. Included in this array of interesting worlds are two particularly intriguing moons - Enceladus and Iapetus. Enceladus appears heavily modified geologically in spite of its small size, and Iapetus has the largest hemispheric albedo dichotomy known. As Cassini/Huygens entered the Saturn system it performed its first close icy satellite encounter with Phoebe on June 11, 2004. Phoebe's measured mass and volume yield a density of 1600 kg m$^{-3}$ $\pm$ 100. The high rock fraction implied by this density, spectral evidence for water ice and carbon dioxide on its surface and images showing a surface of mixed bright and dark material all suggest that Phoebe originated not in the Saturn system but in the solar nebula beyond the asteroid belt, and may be related closely to Kuiper Belt Objects. The results of initial Cassini observations of the icy satellites and plans for upcoming encounters will be reviewed.
<a href='http://saturn.jpl.nasa.gov' >http://saturn.jpl.nasa.gov