Cassini
The Cassini spacecraft used a Jupiter gravity assist to speed its trajectory to Saturn. Between October 2000 and March 2001 the UVIS instrument took spectral images of the Io plasma torus.
The Cassini UVIS Group at LASP is here.
Movie of Io Plasma Torus made by Andrew Steffl from total UV emissions observed by Cassini UVISĀ IoTorus_UVmovie
Cassini UVIS spectral analysis
Cassini CAPS data analysis
This is the Cassini site hosted by the Magnetospheres of the Outer Planets Group. Contact: Fran Bagenal (bagenal at colorado.edu).