Sorry for the lack of updates in the last few days. I have been hard at work correcting some issues I've been having with Celestia both with my Saturn/Cassini plugin (which I need for work to create the graphics in the CICLOPS Looking Ahead articles) and my Jupiter/Galileo plugin. The issue stemmed from attempting to update these plugins to support new features in the bleeding edge version of the 3D Space visualization program. After several days of wanting to kill my computer (must...get...more...RAM) and a lot of help from Chris Laurel, one of Celestia's developers, I think I got everything sorted out, at least with the Jupiter/Galileo plugin.
All this plugin does is use NAIF Spice kernels to generate the position of Galileo, Jupiter, the Galilean Satellites, Amalthea, and Thebe for much improved precision. For example, using the default trajectory file for Galileo in Celestia, and the orbits used for Jupiter and Io, the close approach altitude for the I24 flyby was -1000 km (or thereabouts), obvious not correct. Using Spice Kernels, the C/A altitude is given as 610.5 km, less than a kilometer off the official value. This new update for Celestia allow me to have one version of Jupiter and its moons as opposed to having one Jupiter for before the period covered by the Spice kernels, one during, and one after.
This plugin also adds support for improved precision of each bodies rotation, which may vary due to libration.
The plugin is located at http://pirlwww.lpl.arizona.edu/~perry/Celestia/JupiterSpice.zip. Warning, that file is 163 MB in size.
Keep in mind that his requires the absolutely latest version of Celestia, Version 1.5. Not only that, but you need the latest SVN version, basically a nightly build. The previous link is for the Windows XP file (just copy the Celestia.exe file in that SVN zip file over the Celestia.exe where you installed Celestia). Keep in mind that this build may contain bugs so definitely use with caution. I haven't had an issues with it that I couldn't attribute to having a slow laptop.