 
 
MGS Solar Array CK File for Extended Mission
===========================================================================
 
     Created by Boris Semenov, NAIF/JPL, Thu Jan 11 11:12:48 PST 2007
 
 
Orientation Data in the File
--------------------------------------------------------
 
     This file contains orientation and angular velocity data for the Mars
     Global Surveyor (MGS) +Y and -Y nominal solar array frames --
     'MGS_LEFT_SOLAR_ARRAY' and 'MGS_RIGHT_SOLAR_ARRAY' -- relative to the
     'MGS_SPACECRAFT' frame. The NAIF ID codes for the
     'MGS_LEFT_SOLAR_ARRAY' and 'MGS_RIGHT_SOLAR_ARRAY' frames are -94001
     and -94002.
 
     This C-kernel provides the nominal orientation of the MGS solar
     arrays. However, this does NOT reflect the fact that the -Y solar
     panel did not fully deploy after launch, stopping short by
     approximately 20 degrees, and bent during initial aerobraking almost
     to its nominal position. The actual orientation of this panel, and the
     magnetometer mounted on it, relative to the base body, may be found by
     combining this CK data with the mounting alignment offset data found
     in the SPICE Instrument Kernel (IK) for the magnetometer and -Y panel
     hinge deflection CK file.
 
     MGS solar array angular rates stored in this file are not based on the
     real telemetry but rather calculated from pointing data with the ONLY
     goal to provide smooth usage of SPICE system frames capabilities that
     require rates to be present in the file along with pointing data.
     These rates were computed as follows: for each pointing instance two
     angular velocity vectors representing constant rotations from the
     previous point to this point and this point to the next point were
     computed. These vectors were added and result vector was divided by
     two. For the first and last points the only available rates were used.
 
 
Status
--------------------------------------------------------
 
     This file was created by merging daily CK files produced by the MGS
     Spacecraft Team at LMA, Denver. No timing or any other correction was
     applied to the original data during merge process.
 
 
Pedigree
--------------------------------------------------------
 
     The original CK files used to create this file were officially
     delivered to the MGS project data base by the MGS Spacecraft Team at
     LMA, Denver. These files contained nominal solar array frames
     orientation relative to the spacecraft frame. The orientation was
     computed on the the ground using MGSSCK process from solar array
     gimbal angle values measured on-board and sent to Earth in spacecraft
     housekeeping telemetry. Nominal gimbal angle data sampling rate for
     the solar array gimbals was once every 32 seconds. The individual
     daily files were merged together to provide complete coverage on a
     mission phase basis.
 
     A table containing the complete list of original CK files from which
     data were included in this file is provided at the end of these
     comments.
 
 
Approximate Time Coverage
--------------------------------------------------------
 
     This file covers the following period of the Extended phase
     the mission:
 
        COVERAGE BEGIN TIME (UTC):   2006-OCT-11 00:02:31.027
        COVERAGE END TIME (UTC):     2006-NOV-02 23:24:06.660
 
     This file is a type 3 CK file which provides linear interpolation
     between orientation data points extracted from telemetry. Such
     interpolation is not applied to the whole coverage of the file but
     only inside intervals where enough gimbal telemetry data was available
     and data points were close to each other in time for such
     interpolation to make sense.
 
     Given that nominal gimbal telemetry rate was once every 32 seconds the
     duration of the longest interval over which the data may be
     interpolated was set to 180 seconds, i.e. interpolation was enabled
     only over a four point drop-out. For all requests for data falling
     between two adjacent data points separated by more than 180 seconds
     the SPICELIB CK readers will return a logical flag stating "POINTING
     NOT FOUND".
 
     Tables containing the complete list of valid interpolation intervals
     for the +Y and -Y array data in the file are provided at the end of
     these comments.
 
 
Usage Note
--------------------------------------------------------
 
     In order to use this file an MGS SCLK file containing coefficients
     mapping MGS on-board time to ET and frame definitions for the MGS
     spacecraft and nominal solar array frames must be loaded into a user's
     program.
 
 
Related Kernels
--------------------------------------------------------
 
     This file was created with LSK file naif0008.tls and MGS SCLK file
     MGS_SCLKSCET.00061.tsc.
 
 
Contacts
--------------------------------------------------------
 
     If you have any question regarding this data contact NAIF at JPL:
 
        Charles H. Acton, Jr
        (818)-354-3869
        chuck.acton@jpl.nasa.gov
 
        Boris V. Semenov
        (818)-354-8136
        boris.semenov@jpl.nasa.gov
 
 
Appendix 1: List of the original CK files
--------------------------------------------------------
 
        mgs_solar_array_2006-284.bc
        mgs_solar_array_2006-285.bc
        mgs_solar_array_2006-286.bc
        mgs_solar_array_2006-287.bc
        mgs_solar_array_2006-288.bc
        mgs_solar_array_2006-289.bc
        mgs_solar_array_2006-290.bc
        mgs_solar_array_2006-291.bc
        mgs_solar_array_2006-292.bc
        mgs_solar_array_2006-293.bc
        mgs_solar_array_2006-299.bc
        mgs_solar_array_2006-300.bc
        mgs_solar_array_2006-301.bc
        mgs_solar_array_2006-302.bc
        mgs_solar_array_2006-303.bc
        mgs_solar_array_2006-304.bc
        mgs_solar_array_2006-305.bc
        mgs_solar_array_2006-306.bc
 
 
Appendix 2: Interpolation Intervals for +Y and -Y Array Data
------------------------------------------------------------
 
     Table contains start and stop UTC time for each interval as displayed
     by CKBRIEF utility ran with "-dump -utc" option:
 
 
        CKBRIEF Version: 3.2.0, 2006-11-02. SPICE Toolkit Version: N0061.
 
 
        Summary for: mgs_sa_ext26.bc
 
        Segment No.: 1
 
        Object:  -94001
          Interval Begin UTC       Interval End UTC         AV
          ------------------------ ------------------------ ---
          2006-OCT-11 00:02:31.027 2006-OCT-11 23:59:19.011 Y
          2006-OCT-12 00:02:31.011 2006-OCT-12 23:59:18.995 Y

          (many lines were skipped here to reduce the example size)

          2006-NOV-02 21:16:06.661 2006-NOV-02 22:25:58.660 Y
          2006-NOV-02 23:13:58.660 2006-NOV-02 23:24:06.660 Y
 
 
