PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2007-01-02 NOTE = "SP-Kernel Information" END_OBJECT = TEXT END General information about SPICE SP-kernels ========================================== The purpose of the SP-kernel (SPK), 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. SP Kernels provide the state of a target relative to its center of motion, where ``state'' implies Cartesian position and velocity at a requested epoch. The SPK format is supported by a collection of subroutines that are part of the SPICELIB library, the major component of the NAIF Toolkit. These subroutines can be integrated into user application programs. Information about obtaining the SPICE Toolkit is located in the "software" subdirectory of the main directory of this dataset. To use SP-kernels, a Leapseconds Kernel (LSK) is required. Also, to use SP-Kernels containing states defined relative to non-inertial or project-defined frames, a Frames Kernel (FK) and/or Planetary Constants Kernel (PcK) are required. Refer to the SPK Required Reading (spk.req) document provided with the Toolkit or available from the NAIF Node of the PDS, to get more information on how to access SP-kernel data. Deep Impact SP-kernels Provided in This Directory ================================================= This directory contains the SPICE SP-Kernel files for the Deep Impact Flyby (DIF) and Impactor (DII) spacecraft, Deep Impact mission targets comets Tempel 1 and Boethin, and solar system bodies. All files are in IEEE big endian binary format and suitable for use on UNIX workstations and MACs. The following files are present in this directory. (Only the leading portions of the file names are shown; the file name extensions of the binary SPK files are always ".bsp"): dif_preenc174_nav_v1 SPK file providing DIF spacecraft trajectory as well as ephemerides of the comets Tempel 1 and Boethin and solar system bodies for the whole duration of the mission, based on the last predict pre-encounter trajectory solution 174. dii_preenc174_nav_v1 SPK file providing DII spacecraft trajectory as well as ephemerides of the comets Tempel 1 and solar system bodies for the whole duration of the mission, based on the last predict pre-encounter trajectory solution 174. di_finalenc_nav_v1 SPK file providing an earlier version of the DIF, DII, and Tempel 1 trajectories for the two days period around encounter, reconstructed by DI NAV team from DIF and DII optical navigation data. DIF and DII spacecraft trajectories provided in this SPK use impact site as the center of motion. di_finalenc_nav_v3 SPK file providing the latest version of the DIF, DII, and Tempel 1 trajectories for the two days period around encounter, reconstructed by DI NAV team from DIF and DII optical navigation data. DIF and DII spacecraft trajectories provided in this SPK use impact site as the center of motion. di_finalenc_nav_v3_to06048 SPK file providing the latest version of the DIF, DII, and Tempel 1 trajectories for the two days period around encounter, reconstructed by DI NAV team from DIF and DII optical navigation data and then adjusted by Science Data Center, Cornell University to shift DIF and DII spacecraft trajectories to be with respect to the comet center rather than to the impact site. di_tempel1_ssd_v1.bsp SPK providing Tempel 1 ephemeris spanning from 2000 through 2050, produced at the end of the mission by the Solar System Dynamics Group at JPL. Comet ephemeris data provided in the file is the same as the data provided in di_finalenc_nav_v1, di_finalenc_nav_v3, and di_finalenc_nav_v3_to06048 SPK files. NOTE 1: the best solution for processing the impact data is provided in the file di_finalenc_nav_v3_to06048.bsp. NOTE 2: of the two NAV solutions providing spacecraft trajectories with respect to the impact site, the best one is in the file di_finalenc_nav_v3.bsp. di_finalenc_nav_v1.bsp SPK is included in the archive only because it was used to compute derived geometry items in the set of DI science products generated in November/December 2005. NOTE 3: the "preenc174" SPK files do not provide adequate accuracy for processing of the encounter image data. The encounter (for Impactor) and closest approach times (for Flyby) computed using spacecraft and comet trajectory provided in these SPKs are different from the actual times by over ten seconds. On the other hand these files provided trajectory spanning the whole mission and, therefore, cover every DIF and DII science observation that took place during cruise and far approach. NOTE 4: The following four of these SPKs should be loaded in this order to make sure that the best trajectory solutions are available to the calling application at any given time: dii_preenc174_nav_v1.bsp dif_preenc174_nav_v1.bsp di_tempel1_ssd_v1.bsp di_finalenc_nav_v3_to06048.bsp Deep Impact SPK File Naming Scheme ================================== The Deep Impact SPKs provided on this volume are named according to the following scheme: sc_ident_prod_vX[_modif].bsp where: sc is the name of the spacecraft: "dif" or "dii" or "di" (contains trajectory data for both spacecraft, Flyby and Impactor.) The exception to this is the file for Tempel 1 that provides data only for the comet but still has "di" as the first token indicating that the comet trajectory solution was derived primarily from Deep Impact mission observations. ident is a token identifying the type and coverage of trajectory data provided in the file. Examples: "preenc174" -- complete mission trajectory based on pre-encounter predicted trajectory OD solution 174; "finalenc" -- final reconstructed encounter trajectory, etc. prod is a token identifying the data producer. Examples: "nav" -- DI Navigation team, etc. vX is the file version number. modif is an optional modifier indicating additional processing done to create the file. Example: "to06048" -- "t"empel "o"ffset, solution generated on 2006 DOY 048. The file with the highest version number supersedes all files with the same name but earlier version numbers. 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 the utility programs COMMNT and SPACIT included in the NAIF Toolkit. Contact Information =================== Regarding Deep Impact project specific information provided in this data set and for general information about SPICE system: Boris Semenov (818)-354-8136 Boris.Semenov@jpl.nasa.gov or Chuck Acton (818)-354-3869 Chuck.Acton@jpl.nasa.gov address: Navigation and Ancillary Information Facility (NAIF) Jet Propulsion Laboratory MS 301-125L 4800 Oak Grove Drive Pasadena CA 91109 USA