KPL/MK MESSENGER MDIS Spacecraft Attitude Overlay Meta (FURNSH) Kernel ============================================================================== This kernel contains a list of SPICE kernels to load into programs that wish to make use of the best available MESSENGER spacecraft attitude C-kernels for MDIS analysis. It is to be loaded into SPICE after the mission meta kernels, as it provides supplemental higher rate spacecraft attitude data specifically captured for MDIS usage. Version and Date ---------------------------------------------------------- Version 2.0.0 -- April 1, 2009 -- Scott Turner -- After careful consideration it was decided to make this an addendum to the main meta kernel that covers all MDIS related spacecraft attitude activities. Version 1.0.1 -- March 16, 2009 -- Scott Turner -- Modified kernel variables to match PDS archive structure. Version 1.0.0 -- January 24, 2008 -- Chris Hash -- Initial version References ---------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. furnsh_c (CSPICE) or FURNSH (SPICELIB) module headers. Contact Information ---------------------------------------------------------- Direct questions, comments or concerns about the contents of this kernel to: Mike Reid The Johns Hopkins University Applied Physics Laboratory Mike.Reid@jhuapl.edu Implementation Notes ---------------------------------------------------------- This file is a SPICE meta-kernel used by the SPICE system as follows: programs that make use of this kernel must ``load'' it, normally during program initialization. Loading the kernel loads all of the kernels referenced in the KERNELS_TO_LOAD keyword below. The SPICELIB routine FURNSH and CSPICE routine furnsh_c load this kernel as illustrated below: FORTRAN (SPICELIB) CALL FURNSH ( 'meta_kernel_name' ) C (CSPICE) furnsh_c ( "meta_kernel_name" ) This meta-kernel assumes that the kernels are located in a directory structure as follows: path-to-kernels/ | ck/ If one maintains a duplicate of the officially distributed kernel tree on their system, then one must only edit the path symbol/name pair described in the section below to point to their local kernel "$ROOT" path. This file was created and may be updated with a text editor or word processor. Root Path Definition ---------------------------------------------------------- As discussed above, this meta-kernel assumes that all of the kernels to be loaded are located under a particular directory. The following PATH_SYMBOL/PATH_NAME pair defines the top level or "ROOT" directory underneath which the kernels lie. \begindata PATH_SYMBOLS += ( 'ROOT' ) PATH_VALUES += ( './data' ) \begintext If you have a duplicate kernel tree located somewhere else on your system, you can simply change the value of PATH_VALUES above to point it at your local repository. Kernel Path Definitions ---------------------------------------------------------- These are the names of the directories underneath which individual kernel types are sorted. See the discussion above in the Implementation Notes section for more details on the path structure. \begindata PATH_SYMBOLS += ( 'CK' ) PATH_VALUES += ( 'ck' ) \begintext Kernels to Load ---------------------------------------------------------- The following is the list of kernels to load. They are broken up into types with a brief explanation of the source attitude data going into each kernel. Spacecraft and solar array attitude history derived C-Kernel: These C-Kernels are generated from the merged set of available spacecraft and solar array attitude history packets. None are included here as these are provided in the mission meta kernel for a particular year. Spacecraft attitude history synchronized to MDIS exposures ("0x191") C-Kernel: These C-Kernels are generated from the set of APID 0x191 packets. The 0x191 packets contain spacecraft attitude history only for periods bracketing MDIS exposures. This packet set has not always been captured for every image taken in flight. For example, it was not used for Mercury flyby 1. Whenever available this data is used for processing MDIS geometry: KERNELS_TO_LOAD += '$ROOT/$CK/mdis_sc_040812_081016v1.bc' Spacecraft MDIS Image header derived C-Kernel: This C-Kernel is generated from the spacecraft attitude quaternions attached to the raw image files from MDIS. The comments in this type of CK file describe how these are created in more detail. Typically these files are generated from hand picked images when there is no other source of spacecraft attitude at sufficient resolution. The only kernel in this set is for a portion of Mercury flyby 1 (M1). During the M1 flyby period, the 0x191 packets were not captured (see 0x191 C-kernel section). The alternate source of attitude history (see Spacecraft and solar array attitude history derived C-Kernel section) for certain periods during the M1 flyby had a low sampling rate (1 sample every 5 minutes). This kernel substitutes for only those low rate periods by using the MDIS header quaternions. Specifically it covers: * The first 84 of 104 images of the M1 approach and OPNAV sequences. (Exposure SCLK range 1/0108363798 - 1/0108616201) * 216 images during the M1 approach Wide Angle Camera (WAC) "movie". (Exposure SCLK range 1/0108718077 - 1/0108803286) * 222 images during the M1 departure Narrow Angle Camera (NAC) "movie". (Exposure SCLK range 1/0108846764 - 1/0108899804) \begindata KERNELS_TO_LOAD += '$ROOT/$CK/mdis_hdr_sc_080109_080115v1.bc' \begintext