Here's a list of approved Cycle 6 (July 1996-June 1997) HST observing
programs devoted to the satellites of Jupiter, (or to the surfaces of
other giant planet satellites):

PI           Institution                  Title
--------------------------------------------------------------------------------
Ballester    University of Michigan       HST observations of Io's atmosphere 
                                           coordinated with GALILEO
Brown        Caltech                      Determining the Crustal Composition of
                                            Io through Atmospheric Spectroscopy
Denk         Deutsche Forsch. fuer Luft-  Disk-resolved Spectrophotometry of the 
              und Raumfahrt                Dark Side of Iapetus
Goguen       Jet Propulsion Laboratory    Global Mapping of the Opposition Surge 
                                           on the Galilean Satellites
Hall         The Johns Hopkins University Transit Observations of Io's 
                                           Atmosphere
Hall         The Johns Hopkins University Far-UV Airglow and Albedo Observations 
                                           of Europa and Ganymede
McGrath      STScI                        Io's SO2 Atmosphere: Patchy or Not?
Noll         STScI                        Ultraviolet Spectra of Saturn's 
                                           Satellites: Ion Modification of 
                                           Surface Ice
Noll         STScI                        The Ultraviolet Spectrum of Callisto
Roush        San Francisco State U.       Ultraviolet Spectra of Uranian 
                                           Satellites
Seidelmann   United States Naval Obs.     Recovery of Inner Satellites of 
                                           Neptune
Spencer      Lowell Observatory           Temporal Variability of Io's Surface
                                           and Plumes
Zellner      Georgia Southern University  Spectrophotometry of Inner Jovian 
                                           Satellites

Mike Brown (mbrown@kepler.gps.caltech.edu) supplies this additional information 
on his planned HST program "Determining the Crustal Composition of Io...":

  I've got an HST program for Cycle 6 (with Melissa McGrath) to look for
  silcon, magnesium, and Mg+ in the atmosphere of Io with the FOS 
  (so it >has< to schedule sometime in the next year) around 2800 A.
  Sensitivities are good, so if there is a reasonable amount of silicon
  or magnesium relative to sodium, we should see it easily.
  But who knows what's really reasonable on Io....

John Spencer gives the following info. on his Cycle 6 Io imaging program,
which is with McGrath, McEwen, Nash, Sartoretti, Clark, Ballester, and 
Trauger:

   We will obtain global longitudinal WFPC2 imaging of Io at 2500 A, 3400
   A, and 4100 A on two occasions, in Summer 1996 and Spring 1997, to
   extend Galileo imaging coverage into the ultraviolet.  We hope to look
   for the Loki and Pele plumes at 2500 A, following up on a very
   tentative identification of the Pele plume in 1995 HST images at this
   wavelength.

Jay Goguen gives the following info on his Cycle 6 "Global Mapping of
the Opposition Surge..." program:

   Dates not yet determined - 12 orbits in Cycle 6 for "Global Mapping of
   the Opposition Surge on the Galilean Satellites" (Some observations at
   phase angles less than 1 degree in early July a high priority).