PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM

OBJECT                  = TEXT
   INTERCHANGE_FORMAT   = ASCII
   PUBLICATION_DATE     = 2008-03-25 
   NOTE                 = "SP-Kernel Information"
END_OBJECT              = TEXT
                                                                     
END 


General information about SPICE SP-kernels
==========================================

   The purpose of the SP-kernel -- which stands for S(pacecraft) and
   P(lanet) Kernel -- is to allow ephemerides for any collection of
   solar system bodies, spacecraft or any other objects in 3D space to
   be combined under a common file format, and accessed by a common set
   of subroutines.

   The SPK files can be accessed and manipulated using the SPICE
   Toolkit APIs, calls to which can be integrated into user application
   programs. The information regarding how to obtain the SPICE system
   toolkit for a number of languages and computer platforms is located
   in the ``/software'' subdirectory of the main directory of this data
   set.

   To use SP-kernels, a Leapseconds (LSK) is required. Also, to use
   SP-Kernels containing positions given relative to the non-inertial
   and project-defined frames, a Frame Definitions (FK) and Planetary
   Constants (PCK) files are required.

   Refer to the ``spk.req'' document provided with the toolkit to get
   more information on how to access SP-kernel data.


Cassini SP-kernels provided in this directory 
=============================================
 
   This directory contains the SPICE SP-Kernel files for the Cassini
   spacecraft and for solar system bodies important to the Cassini
   mission. The following files are present in this directory. (Only
   the leading portions of the file names are shown; the file name
   extensions of the binary SPK files are always ``.bsp''):

   Merged SPK files:
 
         Filenames for merged SPK files have the form:

         co_[StartDate]_[EndDate]_[Descriptor]_v[Version]

   where:
         [StartDate]                 File coverage start date (YYYYDOY);

         [EndDate]                   File coverage stop date (YYDOY);

         [Descriptor]                Mission Phase descriptor;

         [Version]                   Numeric version number, starting at 1.

   Specific files are:
 
         co_1997288_97318_launch_v1  Merged solar system body and
                                     spacecraft trajectories covering the
                                     period from launch through TCM 1
                                     (1997-10-15 through 1997-11-14).
                                     Data for satellites of Jupiter
                                     as found in the files jup204
                                     and jup204-s3, are included.
                                     Spacecraft and planetary data come
                                     from the file 000331R_SK_LP0_V1P32,
                                     produced by the Cassini NAV group.

         co_1997319_99311_i_cru_v1   Merged solar system body and
                                     spacecraft trajectories covering
                                     the Interplanetary Cruise phase
                                     (1997-11-15 through 1999-11-07).
                                     Data for satellites of Jupiter,
                                     as found in the files jup204
                                     and jup204-s3, are included.
                                     Spacecraft and planetary data come
                                     from the files 000331R_SK_LP0_V1P32,
                                     000331RB_SK_V1P32_V2P12 and
                                     010420R_SCPSE_EP1_JP83, produced
                                     by the Cassini NAV group.

         co_1999312_00365_o_cru_v1   Merged solar system body and
                                     spacecraft trajectories covering
                                     most of the Outer Cruise phase
                                     (1999-11-08 to 2000-12-31).Data for
                                     satellites of Jupiter as found in
                                     the files jup204 and jup204-s3,
                                     are included. Spacecraft and
                                     planetary data come from the file
                                     010420R_SCPSE_EP1_JP83, produced
                                     by the Cassini NAV group.

   The original spacecraft trajectory files, from which the above merged
   files were made, were produced using a special planetary ephemeris
   file that was merged with the appropriate spacecraft kernel. These
   planetary ephemerides are to be used only in conjunction with this
   spacecraft ephemeris.

   In addition to the merged files described above, files produced by
   the CASSINI NAV team are included. They are named as follows:

         [DeliveryDate][V][T]_[Description]_[StartEvent]_[EndEvent]

   where:

              [DeliveryDate]   Approximate date that the file was delivered
                               (YYMMDD);

              [V]              File version (optional, used only when
                               applicable). It is specified as consecutive
                               letters ``A'', ``B'', ``C'', etc. for each
                               corresponding new version of the same file.

              [T]              Type of the data in the file (optional, used
                               only when applicable). If present, it is a
                               single letter indicating predict trajectory
                               file (``P'') or reconstructed trajectory file
                               (``R'').

              [Description]    File description. This field can be ``SK'' for
                               orbiter spacecraft trajectory SPK file,
                               ``OPK'' for orbiter and probe trajectory
                               SPK file, ``PE'' for planetary ephemeris
                               SPK file, ``SE'' for major satellite
                               ephemeris SPK file,``RE'' for minor
                               satellite ephemeris SPK file, ``IRRE''
                               for outer irregular satellite ephemeris
                               SPK file, or ``SCPSE'' for a merged S/C,
                               Planetary and Satellite Ephemerides
                               file. 

              [StartEvent]     Identifier of the file coverage start event.
                               This field is a string consisting of two
                               elements, <YY>, and <DOY>, where <YY>
                               represents the last two digits of the year in
                               which the event started and <DOY> is the day of
                               the year. ``NA'' indicates not applicable.

              [EndEvent]       Identifier of the file coverage end event. This
                               field follows the same rules as the
                               [StartEvent] field.

   For example, the file:

           040901AP_SK_04192_05058.bsp

   is a binary SPK file delivered on 040901 (Sept. 1, 2004). It is the first
   version (A) of a Predicted SPK file covering from 2004 doy 192 to 2005 doy
   058.

   Note that a few reconstructed trajectory files included in the archive 
   were released in 2005-2006 with incorrect names. They had the version 
   ([V]) and type ([T]) tokens swapped. These files are:

           050105RB_SCPSE_04247_04336.bsp
           050414RB_SCPSE_05034_05060.bsp
           050513RB_SCPSE_05097_05114.bsp
           061129RB_SCPSE_06292_06308.bsp

   Additional ephemeris data, not yet ready for archiving, may be
   available on the NAIF public FTP site. Contact one of the individuals
   listed below for more information.


Kernel File Details
===================

   The most detailed description of the data in each SPK file is provided
   in metadata included inside the comment area of the file. This
   information can be viewed using the utility programs COMMNT and SPACIT
   included in the NAIF Toolkit.


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

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

