Composition and Dynamics of Plasma in Saturn's Magnetosphere

During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where RS is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with ∼3% N+. Over the A and B rings, we found an ionosphere in which O2+ and O+ are dominant, which suggests the possible existence of a layer of O2 gas similar to the atmospheres of Europa and Ganymede.

[1]  M. Grande,et al.  Cassini Plasma Spectrometer Investigation , 2004 .

[2]  Timothy Edward Dowling,et al.  Jupiter : the planet, satellites, and magnetosphere , 2004 .

[3]  John D. Richardson,et al.  An extended plasma model for Saturn , 1995 .

[4]  B. Mauk,et al.  Energy‐time dispersed charged particle signatures of dynamic injections in Jupiter's inner magnetosphere , 1997 .

[5]  J. D. Sullivan,et al.  Plasma observations near saturn: initial results from voyager 1. , 1981, Science.

[6]  W. Ip,et al.  Ion composition and dynamics at comet Halley , 1986 .

[7]  J. Kargel,et al.  The Volcanic and Tectonic History of Enceladus , 1996 .

[8]  T. Hill,et al.  STEADY STATE PLASMA TRANSPORT IN A COROTATION-DOMINATED MAGNETOSPHERE , 1986 .

[9]  Travis W. Hill,et al.  Configuration of the Jovian magnetosphere , 1974 .

[10]  P. Louarn,et al.  Radio and Plasma Wave Observations at Saturn from Cassini's Approach and First Orbit , 2005, Science.

[11]  W. Ip The exospheric systems of Saturn's rings , 1995 .

[12]  V. Shematovich,et al.  Titan's atomic and molecular nitrogen tori , 2004, physics/0407113.

[13]  J. Richardson,et al.  Saturn: Search for a missing water source , 2002 .

[14]  E. Sieveka,et al.  The neutral cloud and heavy ion inner torus at Saturn , 1989 .

[15]  R. E. Johnson,et al.  The production of oxidants in Europa's surface. , 2003, Astrobiology.

[16]  N Achilleos,et al.  Cassini Magnetometer Observations During Saturn Orbit Insertion , 2005, Science.

[17]  R. Beebe Jupiter: The Planet, Satellites and Magnetosphere , 2005 .

[18]  Remo Guidieri Res , 1995, RES: Anthropology and Aesthetics.

[19]  R. S. Wolff,et al.  Plasma Observations Near Uranus: Initial Results from Voyager 2 , 1979, Science.

[20]  D. Shemansky,et al.  Detection of the hydroxyl radical in the Saturn magnetosphere , 1993, Nature.