PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM

OBJECT                  = TEXT
   INTERCHANGE_FORMAT   = ASCII
   PUBLICATION_DATE     = 2003-10-15 
   NOTE                 = "C-Kernel Information"
END_OBJECT              = TEXT
                                                                     
END 


General information about SPICE C-kernels
=========================================

   In the SPICE system, pointing data for an instrument platform, or
   for a specific instrument, are stored C-kernels.  The pointing of a
   platform or an instrument is often expressed in terms of a
   transformation matrix from some standard inertial reference frame to
   a instrument-fixed frame. In the past, the instrument was often a
   camera, and the transformation was thus dubbed the ``C-matrix'';
   hence the choice of C as the name for the pointing kernel.
 
   The data contained in C-kernel files can be accessed and manipulated
   by a collection of FORTRAN 77 subroutines which are part of the
   SPICELIB library. These subroutines can be integrated into user
   application programs. The SPICE system toolkit for a number of
   computer platforms or information regarding how it can be obtained
   is located in the SOFTWARE sub-directory of the main directory of
   this data set.
 
   To use C-kernels, a Spacecraft Clock Kernel (SCLK) is required.
   Also, for C-Kernels containing orientation of a project-defined
   frames, a Frame Definitions File is required.
 
   Refer to the CK.REQ document provided with the toolkit or available
   from the NAIF Node of PDS if SPICE toolkit is not included with this
   data set to get more information on how to access C-kernel data.


DS1 C-kernels contained in this volume
======================================

   This volume contains the SPICE C-Kernel files for the DS1 spacecraft
   and its solar arrays. All files are in IEEE binary format. The
   following files are present in this volume. (Only file names are
   shown; the file name extensions of the binary CK files are always
   ".bc"):

   -- DS1 Spacecraft Orientation CK Files:
   
           m01_sc_YYYY                   DS1 spacecraft reconstructed
                                         Orientation CK files. Four
                                         letters ``YYYY'' indicate the
                                         year covered by the file. See 
                                         important note below regarding
                                         the reconstructed s/c attitude
                                         contained in these files.


           ds1_sc_borrelly_pred          DS1 spacecraft predicted
                                         orientation for Borrely encounter.
                                         Although the reconstructed
                                         orientation is available for
                                         the encounter, this file is
                                         included in the archive
                                         because its comments provide a
                                         a detailed description of the
                                         encounter attitude profile.
                                
   -- DS1 Solar Array Orientation CK Files:
 
           m01_sa_YYYY                   DS1 solar array reconstructed
                                         Orientation CK files. Four
                                         letters ``YYYY'' indicate the
                                         year covered by the file.

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

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


Important Note Regarding Reconstructed Spacecraft Attitude
==========================================================

   Attitude knowledge, represented by quaternions stored in the
   reconstructed s/c orientation CK files, ceased to be valid within a
   short time of the failure of the SRU on November 11, 1999. On-board
   knowledge (based on inertial celestial reference) was not restored
   until 01:00 on June 15, 2000. The reconstructed s/c orientation CKs
   provide no data during this period.

   Attitude knowledge was also subject to gyro drift inaccuracies
   during the following periods, in which our Science Camera/Star
   Tracker lost lock:
 
      2000-07-16T20:00  until  2000-07-19T01:00 
      2001-03-13T16:00  until  2001-03-16T20:00
      2001-07-15T20:00  until  2001-07-24T18:00
      2001-08-16T12:00  until  2001-08-24T11:00 
      2001-09-13T17:00  until  2001-09-14T01:00
      2001-12-02T16:00  until  2001-12-04T23:00

   Although the magnitude of the inaccuracy is not known for each
   period, the reconstructed s/c orientation CKs provide data during
   these periods because the attitude was determined using real gyro
   measurements and may be, at least at the starts of the intervals,
   close to reality.


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

   Regarding DS1 project specific information provided in this data set
   and for general information about SPICE system:
   
      Charles H. Acton, Jr, 
      (818)-354-3869, 
      Chuck.Acton@jpl.nasa.gov, 
      
   or 
   
      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