The Heavy Ion Counter was added to the Galileo spacecraft to monitor the environment for energetic heavy ions with the potential to cause single event upsets in the spacecraft electronics. In addition to their engineering value, these observations are of course also of scientific interest. In particular, heavy ion spectra at Jupiter can be used to study composition, diffusion, and acceleration of these particles. Other scientific goals include observations of energetic particles associated with solar flare events, of cosmic rays, and of anomalous cosmic rays.

Technical Documentation

Instrument

Pictures of the HIC instrument are available here:

The Heavy Ion Counter is based on the Voyager CRS instrument and is described in an instrument paper which was part of a special Galileo issue of Space Science Reviews 60, 305-315, 1992. A good overview of the HIC instrument is also available through JPL's Galileo Mission Homepage.

For more detail the technical report, Science Requirements Document, (SRL Technical Report 85-02) can be viewed. This SRD also documents the data as it comes from the instrument.

HIC Data Format

In Phase II of the mission, HIC data are compressed substantially by software in the spacecraft's central data system before being downlinked. The compressed data are described in SRL Technical Report 97-01, "HIC Collect and Compress Routine".

Galileo-HIC data are carried, along with related header information, in an Instrument Packet File (IPF). Within each IPF are several data packets, structured in the standard formatted data unit (SFDU) form, which contain the actual Galileo-HIC rate count data. Overviews of the HIC IPF and SFDU data structures are available here. The original documentation on IPF/SFDU formats and a detailed description of the SFDU structure, both from Betsy Wilson and JPL, are also available. Raw IPFs are downloaded from the Galileo Science Vax Cluster (GLLSVC) at JPL and translated from binary data to a readable ASCII format with a tool called ipftoascii, which outputs rate and event data.

HIC Data Processing Routines

Available at the preceding link are documentation detailing the processing of HIC data from raw, binary data to finished data products such as rate plots and histograms. Also included here are documentation on the data processing tools.

Miscellaneous

For quick reference, a glossary of acronymns is available for those associated with the Galileo-HIC documentation.
Other sources of definitions include:

Galileo HIC Related Publications

"Effects of Absorption by Io on Composition of Energetic Heavy Ions" T. L. Garrard, E. C. Stone, N. Murphy. (SRL Publication 96-27), Science 274, 393-394, (1996).

Access to Current Galileo Data

HIC observations of the solar flare related ion fluxes in October 1989 and November 1992 are being made available via the Planetary Data System (PDS).

The Galileo Mission home page at JPL provides updates on Galileo, including several encounter images. The original images are generally available from the Planetary Data System.

Access to Other Galileo Experiments and Data

Data from the Energetic Particle Detector (EPD) can be accessed through the Johns Hopkins University-Applied Physics Laboratory EPD site.

The Galileo Plasma Particle Investigation (PLS) homepage at the University of Iowa gives links to PLS specific documentation and data, as well as links to many Galileo related WWW sites.

Other Galileo Related Homepages:

Project Information at Caltech

The contact person for the HIC project at the Caltech Space Radiation Laboratory is Tom Garrard. For questions and comments regarding this website, please contact Damien Chua or Vani Manjunath.

Email Tom Garrard: tlg@srl.caltech.edu

Email Damien Chua: damien@srl.caltech.edu

Email Vani Manjunath: deedee@srl.caltech.edu

Last Revised: Tuesday April 29, 1997