PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM

OBJECT                  = TEXT
   INTERCHANGE_FORMAT   = ASCII
   PUBLICATION_DATE     = 2003-10-15
   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 format is supported by a collection of subroutines that are
   part of the SPICELIB library, the major component of the NAIF
   Toolkit. 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 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 (FRAMES) and
   Planetary Constants (PcK) files are required.
 
   Refer to the SPK.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 SP-kernel data.


DS1 SP-kernels provided in this directory 
=========================================

   This directory contains the SPICE SP-Kernel files containing
   trajectory of the DS1 spacecraft and its targets -- asteroid Braille
   and comet Borrelly. All files are in IEEE binary format and suitable
   for ftp binary transfer to use on UNIX workstations and MACs. The
   following files are present in this directory. (Only file names are
   shown; the file name extensions of the binary SPK files are always
   ".bsp"):

         ds1_radionav            SPK file, containing DS1 trajectory
                                 and covering the whole mission,
                                 created by the DS1 Radio NAV team
                                 using radio tracking data

         ds1_opnav_braille       SPK file, containing DS1 trajectory
                                 and Braille ephemerides during the
                                 Braille encounter, created by the DS1
                                 Optical NAV team using optical
                                 navigation data

         ds1_opnav_borrelly      SPK file, containing DS1 trajectory
                                 and Borrelly ephemerides during the
                                 Borrelly encounter, created by the DS1
                                 Optical NAV team using optical
                                 navigation data

         de405s                  SPK file containing JPL's Planetary
                                 Ephemerides (DE) 405.


Important Note Regarding SPK Files
==================================

   The SPKs produced by DS1 Optical NAV team were created by processing
   images taken during the approach to and departure from the target.
   These solutions provide the best trajectory relative the specific
   target ephemerides that has been included in these SPKs to ensure
   that the s/c trajectory and that specific target ephemerides are
   always used together. These SPKs provide more accurate trajectory
   relative the target and, therefore, should be used to compute
   derived geometry during the encounters.

   The substantial difference between the DS1 trajectory provided by
   the OPNAV and Radio NAV solutions -- on average about 400 km for the
   Braille encounter and about 120 km for the Borrelly encounter -- can
   be attributed to the error in the knowledge of the target position.
   Since the OPNAV solution was done relative to the target and the
   Radio NAV was done relative to the Solar System ephemerides, the
   error is the target position became the main contributor to the
   difference between the two spacecraft trajectory solutions.

   Unfortunately the coverage of the OPNAV SPKs is relatively short,
   starting about a month before each encounter and ending shortly
   after it. For this reason the Radio NAN SPKs should be used wherever
   OPNAV SPK coverage is not available. To achieve correct access
   priority one could load all DS1 SPKs at once with the following
   meta-kernel:

      \begindata

         KERNELS_TO_LOAD = (
                            'de405s.bsp'
                            'ds1_radionav.bsp'
                            'ds1_opnav_braille.bsp'
                            'ds1_opnav_borrelly.bsp'
                           )

      \begintext 
   

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 utility programs COMMNT and
   SPACIT included into the NAIF Toolkit.
   

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