PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM

OBJECT                  = TEXT
   INTERCHANGE_FORMAT   = ASCII
   PUBLICATION_DATE     = 2007-06-25
   NOTE                 = "This file describes the files in the
                           extras/mk directory of this archive."
END_OBJECT              = TEXT

END

Meta-kernels for the Cassini mission
====================================

   This directory contains the meta-kernel files (a.k.a "furnsh" files)
   that provide lists of the archived kernels included in this data set
   suitable for loading into a SPICE-based application via the high
   level SPICE data loader routine FURNSH. Using these meta-kernels
   makes it easy to load with one call a comprehensive SPICE data
   collection for a given period. Like the text kernels archived in
   this data set, these meta-kernels are UNIX text files that have
   lines terminated with a line feed character, LF (ASCII 10).

   The names of the meta-kernels provided in this directory follow this
   pattern:

      cas_YYYY_vVV.tm

   when ``YYYY'' is the year covered by the kernels listed in the file
   and ``VV'' is the file version.

   Multiple versions of a meta-kernel for the same year may exist if
   new kernels were added to the archive in a later release and the
   meta-kernel for that year had to be updated to incorporate them. The
   reasons for adding new kernels include (but are not limited to)
   adding new kinds of kernels, adding new versions of existing kernels
   containing more complete or more accurate data, and adding new
   versions of existing kernels superseding the existing kernels that
   had errors. If more than one meta-kernel file for the same year is
   present, then the file with the latest version number supersedes all
   earlier versions. The latest meta-kernels can be loaded together in
   any order to provide coverage for more than one year. (Note that on
   some environments loading too many kernels at once may slow down
   data access.)
 
   Although the meta-kernels were created such that on a UNIX
   workstation they can be loaded into a SPICE-based application
   directly from the root directory of the data set -- because the
   PATH_VALUES keyword is set to './data' and '/' is used as the path
   delimiter -- it is recommended that users make local copies of these
   files and update the PATH_VALUES keyword in each of them to point to
   the actual location of the data set's 'data' directory on their
   system. Additional changes including replacing '/' and '\' in all
   path specifications and converting UNIX line terminator to
   terminators native to the user's system may be required to use these
   meta-kernels on non-UNIX workstation.
   
   The following guidelines were followed to pick and set priority --
   determined by the order in which the kernel files are listed, with
   the latest one taking precedence -- for the kernel files included in
   these meta-kernels:

      -  the latest archived versions of LSK, SCLK, IK, FK, and CDA CK
         were included

      -  no PCK files were included because the multitude of PCK files
         produced by the CASSINI project and archived in this data set
         did not allow NAIF to make a reasonable pick for this kernel
         type

      -  both the predicted and reconstructed spacecraft orientation
         CKs were included with the reconstructed CKs taking precedence
         (listed last) and predicted CKs having lower priority and used
         when the reconstructed CKs do not provide coverage

      -  a subset of small satellite SPKs providing the most complete
         coverage was included. If two or more SPKs covered the same
         time span for a body were included, the latest SPK was listed
         last for higher priority

      -  no ISS c-smithed CKs were included due to the very sparse
         coverage provided by these files

      -  no EK files were included due to the low likelihood that EKs
         would be needed for a SPICE-based application using the
         Cassini SPICE data

   WARNING: since the lists of kernels in these meta-kernels do not
   include any PCK files, these data collections are not usable for
   computing derived parameters that require knowledge of the natural
   body orientations, rotations and shapes. It is the user's
   responsibility to identify the PCK(s) most suitable for his/her
   application and to load this(these) PCK(s) in addition to these
   meta-kernels.


Contact Information
===================

   Regarding Cassini project specific information provided in this data
   set and for general information about SPICE system, contact:

      Boris Semenov
      (818)-354-8136
      Boris.Semenov@jpl.nasa.gov

   address:

      Navigation and Ancillary Information Facility (NAIF)
      Jet Propulsion Laboratory
      MS 301-125L
      4800 Oak Grove Drive
      Pasadena CA 91109 USA
