PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM

OBJECT                  = TEXT
   INTERCHANGE_FORMAT   = ASCII
   PUBLICATION_DATE     = 2008-11-12
   NOTE                 = "Viking Orbiter 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.


Viking Orbiter SP-kernels Provided in This Data Set
===================================================

   The following Viking Orbiter SP-kernels are provided in this data set
   (only name portion of the file name is shown on the right; the
   extension of all file names is ``.bsp''):

   -- Viking Orbiter Spacecraft Trajectory SPK files:

      vo1_sedr          VO1 primary, extended, continuation and survey
                        mission trajectory SPK file based on spacecraft
                        position and velocity information from SEDR
                        (Supplemental Experiment Data Record) files
                        generated by the Viking Project.

      vo2_sedr          VO2 primary, extended and continuation
                        mission trajectory SPK file based on spacecraft
                        position and velocity information from SEDR
                        (Supplemental Experiment Data Record) files
                        generated by the Viking Project.

      vo1_rcon          VO1 primary, extended and continuation mission
                        trajectory SPK file based on VO orbit reconstruction
                        made in 1995 by A. Konopliv, JPL.

      vo2_rcon          VO2 primary, extended and continuation mission
                        trajectory SPK file based on VO orbit reconstruction
                        made in 1995 by A. Konopliv, JPL.

      vo1_ext_gem       VO1 continuation and survey mission trajectory
                        SPK file based on spacecraft position
                        information from GEM files by USGS. This file
                        covers only 33 short periods of time at the end
                        of the mission.

   -- Solar System Bodies Ephemeris data SPK file:

      mar033            SPK file containing JPL's Development Ephemerides
                        (DE) 405 and Mars Satellite Ephemerides (MAR)
                        MAR033.7.

   All this data is actual (reconstructed).


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.

   The Konopliv's trajectory solution, generated years after the
   mission using substantially better Mars gravity field model, is
   definitely more accurate. But unfortunately, it does not cover the
   final phase of the VO1 mission. Refer to the ``vo_spks.txt'' document
   located in the ``document'' directory of this volume to get more
   information on comparison of the trajectory from original SEDR and
   Konopliv's data sets.


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

   Regarding VO 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