PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2012-01-13 NOTE = "C-Kernel Information" END_OBJECT = TEXT END General information about SPICE C-kernels ========================================= In the SPICE system, pointing data for an instrument platform, or for a specific instrument, are stored C-kernels. The pointing of a platform or an instrument is often expressed in terms of a transformation matrix from some standard inertial reference frame to a instrument-fixed frame. In the past, the instrument was often a camera, and the transformation was thus dubbed the ``C-matrix''; hence the choice of C as the name for the pointing kernel. The data contained in C-kernel files can be accessed and manipulated by a collection of APIs which are part of the SPICE Toolkit library. These subroutines/functions 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'' subdirectory of the main directory of this data set. To use C-kernels, a Spacecraft Clock Kernel (SCLK) is required. Also, for C-Kernels containing orientation of a project-defined frames, a Frame Definitions File is required. Refer to the ``ck.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 C-kernel data. Stardust C-kernels contained in this Data Set ============================================= This data set contains the SPICE C-Kernel files for the Stardust spacecraft and NAVCAM instrument. The following binary CK files are present in this data set (only file names are shown; the file name extensions of the binary CK files are always ".bc"): sdu_sc_rec_YYYY[_vX] Stardust spacecraft orientation CK files. Each of these files covers the year specified by the YYYY token of the name. The file for the year 2003 also covers the first half of January 2004, during which the Wild 2 encounter and post encounter observations have occurred. This longer coverage is indicated by the YYYY token set to 2003_w2. The file for 2005 also covers the beginning of 2006, through the end of the Earth return phase. These CKs contain s/c orientation that was extracted from the channelized telemetry, small forces packets, and NAVCAM image headers. If more than one file is present for any of the years, the file with latest version (_vX) supersedes all other files for that year. sdu_sc_rec_next Stardust spacecraft orientation CK file covering the NEXT mission (2006-2011). This CKs contain s/c orientation that was extracted from the channelized telemetry, small forces packets, and NAVCAM image headers. sdu_sc_rec_w2_opnav Stardust spacecraft orientation CK file, containing s/c attitude for the Wild 2 encounter, determined as part of the Optical Navigation (OPNAV) team geometry solution for the encounter. sdu_sc_rec_t1_opnav Stardust spacecraft orientation CK file, containing s/c attitude only for the 72 small intervals covering images taken during Tempel 1 encounter, determined as part of the Optical Navigation (OPNAV) team geometry solution for the encounter. sdu_nc_rec[_vX][_type2] NAVCAM orientation CK files. These files contains data required to compute NAVCAM pointing w.r.t the spacecraft. The CKs without ``type2'' in the name are type 1 CK files containing discrete orientation points computed from the mirror angle values included in the image headers and corresponding to the exact image exposure start times. Therefore, they cannot be used to compute the camera view direction for any other times. To get these exact times users interested in computing NAVCAM orientation using these CKs must start with SCLK values provided in the SPACECRAFT_CLOCK_START_COUNT keywords in the NAVCAM image labels and convert these SCLKs to other time system(s) to access SPICE data. Starting with UTC times from the NAVCAM labels will result in a small round off and the pointing will not be found. The CKs with ``type2'' in the name are type 2 CK files containing orientation data covering small windows, from exposure start minus 1 SCLK tick to exposure stop plus 1 SCLK tick, for constant mirror position across windows, computed from the mirror angle values included in the image headers. These CKs can be used to compute NAVCAM orientation at any time within the image exposures. If more than one NAVCAM CK file is present, the file with latest version (_vX) supersedes all other files. Because ``type2'' CKs are more usable, they supersede non-``type2'' CKs with the same versions. sdu_coll_nom[_vX] Dust collector orientation CK files. These files contain commanded orientation of the dust collector grid with respect to the spacecraft. If more than one collector CK file is present, the file with latest version (_vX) supersedes all other files. Kernel file details =================== The most detailed description of the data in a binary CK 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. Kernel Loading Priority ======================= In order to provide the best available spacecraft and instrument orientation to the whole primary and NEXT missions, the following subset of CK files included in this directory must be loaded in the following order: sdu_coll_nom_v1.bc sdu_nc_rec_v3_type2.bc sdu_sc_rec_1999_v2.bc sdu_sc_rec_2000_v2.bc sdu_sc_rec_2001_v2.bc sdu_sc_rec_2002_v2.bc sdu_sc_rec_2003_w2_v2.bc sdu_sc_rec_2004_v2.bc sdu_sc_rec_2005_v2.bc sdu_sc_rec_next.bc sdu_sc_rec_w2_opnav.bc sdu_sc_rec_t1_opnav.bc Contact information =================== Regarding Stardust 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