Data Set Overview
      =================

      This data set includes the complete set of SPICE data for the
      Mars Odyssey in the form of SPICE kernels, which can be accessed
      using SPICE software available to read these files.

      The SPICE data contains geometric and other ancillary information
      needed to recover the full value of science instrument data. In
      particular SPICE kernels provide spacecraft and planetary
      ephemerides, instrument mounting alignments, spacecraft
      orientation and spacecraft sequences of events. Data needed for
      relevant time conversions is also included.


      Data Types (SPICE kernel types)
      ===============================

      SPK kernels contain ephemerides for spacecraft, planets,
      satellites, comets and asteroids as well as for moving or
      fixed spacecraft and instrument structures. They provide
      position and velocity, given in a Cartesian reference frame.
      SPK files are located under the ``data/spk'' directory of 
      this data set.

      PCK kernels contain certain physical, dynamical and
      cartographic constants for target bodies, such as size and shape
      specifications, and orientation of the spin axis and prime
      meridian. PCK files are located under the ``data/pck'' directory
      of this data set.

      IK kernels (Instrument description kernels) give descriptive and
      operational data peculiar to a particular scientific instrument,
      such as internal timing relative to the spacecraft clock and
      field-of-view model parameters. IK files are located under the
      ``data/ik'' directory of this data set.

      CK kernels describe pointing, containing a transformation
      traditionally called the C-matrix which is used to determine
      time-tagged pointing (orientation) angles for a spacecraft
      structure upon which science instruments are mounted. CK files
      are located under the ``data/ck'' directory of this data set.

      EK (Events) kernels are derived from the integrated sequence of
      events used to produce actual spacecraft commands. EK files are
      located under the ``data/ek'' directory of this data set.

      LSK (Leapseconds) kernels contain the leapseconds and the values
      of other constants required to perform a transformation between
      Universal Time Coordinated (UTC) and Ephemeris time (ET). LSK
      files are located under the ``data/lsk'' directory of this data
      set.

      SCLK (Spacecraft Clock) kernels contain on-board clock calibration
      data required to perform a mapping between Ephemeris time (ET)
      and spacecraft on-board time (SCLK.) SCLK files are located under
      the ``data/sclk'' directory of this data set.


      FK (Frame Definitions) kernels contain information required to
      define reference frames, sources of frame orientation data and
      inter-connections between these frames and other frames supported
      within the SPICE system. This includes mounting alignment
      information for each instrument.  FK files are located under
      the ``data/fk'' directory of this data set.


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

      A brief overview of the different types of M01 kernels included
      in this data set is provided in the CONFIDENCE_LEVEL_NOTE section
      of this file while details specific to individual files are found
      in the ``*info.txt'' files in the corresponding data directory.
      The most detailed description of the data in each file is
      provided in metadata included inside the file -- in the
      description area of text kernels or in the comment area of binary
      kernels.


      Software
      ========

      The SPICE Toolkit contains software modules needed to read
      SPICE kernel files. SPICELIB software is highly documented
      via internal headers. Additional documentation is available
      in separate ASCII text files called Required Reading files.
      For example, the S- and P- Kernel (SPK) Required Reading File,
      named SPK.REQ, describes use of the SPK kernel file readers
      and contains sample programs.

      The latest SPICE Toolkit for a variety of computer platforms such
      as PC, Mac, SUN, HP, SGI, VAX, DEC Alpha, etc. is available at
      the NAIF Node of PDS electronically (via anonymous FTP and WWW
      servers). Refer to information in ``software/softinfo.txt'' for
      additional details. Each version of the Toolkit is also archived
      at the NASA National Space Science Data Center.


      Loading Kernel Files into a SPICE-based Application
      ===================================================

      The easiest way to make data from a collection of SPICE kernels
      available to a SPICE-based application is to list these kernels
      in a meta-kernel and load it into the program using the high
      level SPICE data loader routine FURNSH. This data set provides
      such meta-kernel(s) under the ``extras/mk'' directory. For more
      information about the MGS meta-kernel(s), see the file
      ``extras/mk/mkinfo.txt''.

This volume contains SPICE kernel files created during mission
      operations and after mission data reconstruction and analysis.
      Some general information about this collection follows here,
      but the prospective user is also referred to extensive
      descriptions about each file that are stored inside each kernel
      file. These metadata provide detailed information regarding
      the information source from which the data were derived, the
      type of processing applied to the source data, applicability
      of the data, etc. Metadata are located in the ``comment area''
      for binary kernel types (SPK, CK, ESQ), accessible using either
      the COMMNT or SPACIT utility program found in the NAIF Toolkit.
      Metadata are located after ``\begintext'' markers within the
      text kernel types (PCK, IK, FK, LSK, SCLK, MK), accessible by
      using any available text file display tool such as a word
      processor, text editor, or the unix ``more'' or ``cat''
      commands.

      In some cases data accuracy information does not exist, or
      may be estimated after mission completion.

      Where there are questions about data accuracy or ``confidence''
      not addressed herein the reader is invited to examine subsequent
      SPICE archive releases associated with this data set (if such
      exist), or to contact the NAIF node of the Planetary Data System
      for possible further information.


      SPK Files
      =========

      Three kinds of SPK files are provided in this archive: SPK
      files for the spacecraft orbit, SPK files for Phobos, Deimos,
      Mars, Earth and Sun, and SPK files for the solar array and
      high gain antenna structures. 

      Spacecraft Orbit SPK Files
      --------------------------

      Most of the included SPK files provide the orbit of the ODY
      spacecraft. These files came from three different producers --
      Mars Odyssey Navigation Team (NAV) and Alex Konopliv and Eugene
      Fahnestock of the Solar System Dynamics group of JPL. The NAV SPK
      files provide the reconstructed trajectory solution generated for
      use by various project teams during mission operations. The
      Konopliv's and Fahnestock's solutions were done at a later time
      using more recent and complex models and, in general, is more
      accurate. Refer to the detailed comments provided in the comment
      area of these files for more information about accuracy of the
      trajectory stored in the these files, models used in process,
      etc.

      This data set also includes the orbit number files generated
      during the mission using the NAIF's ORBNUM utility program for
      each of the NAV spacecraft trajectory SPK files for the orbital
      phases of the mission. These files are not SPICE kernels; for
      this reason they are provided in the ``extras/orbnum'' directory.
      For more information about Mars Odyssey orbit number files, see
      the file ``extras/orbnum/orbinfo.txt''.

      Solar System Body SPK Files
      ---------------------------

      The MAR033 Martian satellite ephemeris SPK files provided in this
      data set were used by the project up to the fall of 2006. They
      contain ephemeris data for Phobos, Deimos, Earth and the sun.
      Formal one-sigma accuracy information for Phobos and Deimos are
      reported as follows:

         Body         Downtrack      Crosstrack      Radial    
                     Uncertainty     Uncertainty   Uncertainty
         ------      -----------     -----------   -----------
         Phobos         15 km           7 km          3 km
         Deimos         30 km          16 km          3 km

      The MAR063 Martian satellite ephemeris SPK files provided in this
      data set superseded the MAR033 files and were used by the project
      starting in the fall of 2006. As the MAR033 files the MAR063 SPKs
      contain ephemeris data for Phobos, Deimos, Earth and the sun.
      Formal one-sigma accuracy information for Phobos and Deimos are
      reported as follows:

         Body         Downtrack      Crosstrack      Radial    
                     Uncertainty     Uncertainty   Uncertainty
         ------      -----------     -----------   -----------
         Phobos          5 km           2 km          2 km
         Deimos         10 km           3 km          3 km

      Accuracies for Mars-Sun and Mars-Earth directions (positions
      obtained from SPK files) are at the level of 0.001 arc-sec (1
      sigma).

      Spacecraft Solar Array and HGA Structures SPK File
      --------------------------------------------------------------

      Included in the SPK archive is a file containing location
      information (fixed offsets) for spacecraft structures--the
      high gain antenna and solar array. See the metadata in this
      file--found in the comment area--for detailed descriptions
      of how the file was produced.

      For more information about Mars Odyssey SPK files, see the file
      ``data/spk/spkinfo.txt''.

      CK Files
      ========

      C-kernel files provide orientation of a structure:
      the spacecraft bus, the solar array, or the high gain
      antenna. There is only one reconstructed CK file provided
      for each structure for a given mission phase or a portion of
      a mission phase. All three kinds of reconstructed CK files
      are produced from engineering telemetry downlinked from the
      spacecraft. As is often the case with spacecraft engineering
      telemetry-based measurements, considerable uncertainty exists
      as to the accuracy of such measurements, and, data quality
      (accuracy and completeness) can vary significantly.

      For the spacecraft bus, in addition to the reconstructed CKs,
      this data set also includes predicted nominal nadir-pointed
      orientation CK files and CK files providing nominal orientation
      during ROTO periods. The ``nadir'' CKs contain orientation
      computed assuming that the spacecraft was pointing nadir at all
      times or was pointing off nadir by a constant yaw or roll angle
      (for HGA mitigation periods in 2005 and 2009). The ``ROTO'' CKs
      contain orientation computed assuming that the spacecraft was
      pointing according to the commanded off-nadir roll angle; they
      cover only the periods when the spacecraft was at ROTO
      orientations. Both types of the nominal orientation CKs should be
      used only when the reconstructed CKs don't provide coverage and
      the spacecraft is known to be in the pointing mode matching the
      mode represented by the nominal CK files. For such periods the
      nominal orientation usually matches the actual orientation to
      about or better than 0.2 degrees.

      Reconstructed Solar Array CK Files
      --------------------

      CK files providing orientation of the solar array relative
      to the spacecraft bus are provided to support any spacecraft
      dynamics and/or instrument view obstruction analysis that
      would require knowledge of the solar orientation and position.

      Reconstructed High Gain Antenna CK Files
      --------------------------

      CK files providing orientation of the high gain antenna (HGA)
      relative to the spacecraft bus are provided to support the
      radio science analysis, spacecraft dynamics analysis, and 
      instrument view obstruction analysis.

      Reconstructed Spacecraft Bus CK Files
      -----------------------

      CK files providing the orientation of the spacecraft bus (``the
      spacecraft'') are provided to support interpretation of data
      obtained by all science experiments. At the time of this archive 
      release there are no known reports assessing accuracy of the 
      orientation provided in these files.

      Caution on Using CK Files
      -------------------------

      While not a data accuracy issue, the CK user is nevertheless
      cautioned to understand and properly use the data found and
      tolerance arguments that are inputs to the CK reader provided
      in the SPICE Toolkit. Descriptions about how to read CK files
      are found in the CK reader routine headers (top of the source
      code files) and in the ``CK Required Reading'' document; these
      are contained in each SPICE Toolkit package.

      For more information about Mars Odyssey CK files, see the file
      ``data/ck/ckinfo.txt''.


      PCK Files
      =========

      PCK files provide size, shape and orientation data for ``target''
      bodies such as Mars, Phobos and Deimos. A description of these
      data items and reference to their source is provided inside
      the PCK file, which is a simple text file that can be viewed
      using any word processor, text editor or text display utility.
      The data for the PCK provided in this archive are official 
      IAU/IAG/COSPAR values accepted in 2000. 

      For more information about Mars Odyssey PCK files, see the file
      ``data/pck/pckinfo.txt''.


      FK Files
      ========

      Frames kernel files provide specifications for how one reference
      frame is defined relative to another frame. The ODY FK provided
      in this data set contains a complete set of frame definitions for
      the spacecraft, its structures such as solar array and antennas,
      and all of its science instruments. Meta information provided in
      the comments included in this file consists of the frame
      definitions, description of the frame relationships, source of
      and accuracy of the mounting alignment information, etc. 

      For more information about Mars Odyssey FK files, see the file
      ``data/fk/fkinfo.txt''.


      IK Files
      ========

      Instrument kernel files provide specifications for the optical
      and physical instrument parameters and -- where applicable --
      field-of-view size, shape and orientation for the named
      instrument. Metadata describing these estimates are provided in
      each IK file included in this archive. 

      For more information about Mars Odyssey IK files, see the file
      ``data/ik/ikinfo.txt''.


      SCLK Files
      ==========

      Spacecraft Clock kernel files provide a tabulation of data
      needed for converting time measurements between ephemeris time
      (ET) and spacecraft clock time (SCLK). A SPICE SCLK file is
      made from a similar file--SCLK/SCET file, or SCLKvSCET
      file--produced by another mission entity. Each newly made SCLK
      file fully replaces the previous SCLK file.

      For ODY the time correlation accuracy provided in SCLK/SCET
      files is informally reported by the Lockheed Martin spacecraft
      team to be better than 100 milliseconds during cruise and
      better than 10 milliseconds during orbital phases. (NAIF has
      not attempted to obtain or produce an independent corroboration
      of these LMA estimates.) The SPICE SCLK file has essentially
      the same accuracy as the SCLK/SCET file.

      SPICE software does not prohibit an SCLK file from being used
      for time conversions occurring for ``future times'' (or more
      accurately, for epochs that occur later than the epoch of the
      last telemetry data used in producing the last correlation
      coefficients found in the SCLK file). Such ``predict'' time
      conversions are likely to be inaccurate (changed somewhat)
      once the epoch of interest has been passed.

      For more information about Mars Odyssey SCLK files, see the file
      ``data/sclk/sclkinfo.txt''.


      LSK Files
      =========

      Leapseconds kernel files provide a tabulation of ``leapseconds''
      and some other terms used in converting time measurements
      between ephemeris time (ET) and Universal Time (UTC). ``Spacecraft
      Event Time'' (SCET) is the commonly used name for UTC events
      measured at the spacecraft.

      Metadata describing how the LSK data are obtained or computed
      is contained inside the LSK text file. The time conversion
      provided by SPICE LSK files is accurate to approximately
      0.000030 seconds.

      For more information about Mars Odyssey LSK files, see the file
      ``data/lsk/lskinfo.txt''.


      EK Files
      ========

      Two kinds of Events kernel (EK) files are included in this
      archive: Experimenter's Notebook EKs and Sequence EKs.  Each of
      these kinds is briefly described below.

      Experimenter's Notebook EKs kernels are a digital analog to the
      traditional paper laboratory notebook. Hence Experimenter's
      Notebook entries represent truth only as seen by the author of
      the notes--there is no attempt made to independently validate any
      aspect of Experimenter's Notebook information.

      Sequence EKs comprise a summary of all commands sent to the
      spacecraft as well as some ground system events and instrument
      state (status) summaries. All Sequence EK entries are time
      tagged. In this archive includes Sequence EKs created the
      automated process for providing ``as run'' inputs reflecting what
      was actually sent to the spacecraft, and what execution times
      were used.

      For more information about Mars Odyssey EK files, see the file
      ``data/ek/ekinfo.txt''.