PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2024-02-01 NOTE = "SP-Kernel Information" END_OBJECT = TEXT END General information about SPICE SP-kernels ========================================== The purpose of the SP-kernel -- 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. The SPK files can be accessed and manipulated using the SPICE Toolkit APIs, calls to which can be integrated into user application programs. The information regarding how to obtain the SPICE system toolkit for a number of languages and computer platforms is located in the ``/software'' subdirectory of the main directory of this data set. To use SP-kernels, a Leapseconds (LSK) is required. Also, to use SP-Kernels containing positions given relative to the non-inertial and project-defined frames, a Frame Definitions (FK) and Planetary Constants (PCK) files are required. Refer to the ``spk.req'' document provided with the toolkit to get more information on how to access SP-kernel data. Cassini SP-kernels provided in this directory ============================================= This directory contains the SPICE SP-Kernel files for the Cassini spacecraft and for solar system bodies important to the Cassini mission. The following files are present in this directory: Final CASSINI reconstruction SPKs produced by R.A. Jacobson: 200128RU_SCPSE_[START]_[END].bsp where: 200128 File delivery date in YYMMDD format - January 28, 2020. RU Reconstructed from Uniform models for Saturnian system natural bodies. SCPSE stands for 'spacecraft, planet,and satellite ephemeris'. [START] File start date in Year-DOY where year is the last 2 digits. (YYDOY); [END] File end date in Year-DOY where year is the last 2 digits. (YYDOY); For example, the file: 200128RU_SCPSE_17235_17258.bsp refers to a reconstructed spice kernel delivered on January 28, 2020 that is begins on Day of Year 235 in 2017 and ends on DOY 258 in 2017. Merged SPK files for cruise, named as follows: co_[StartDate]_[EndDate]_[Descriptor]_v[Version].bsp where: [StartDate] File coverage start date (YYYYDOY); [EndDate] File coverage stop date (YYDOY); [Descriptor] Mission Phase descriptor; [Version] Numeric version number, starting at 1. Specific files are: co_1997288_97318_launch_v1.bsp is a merged solar system body and spacecraft trajectories covering the period from launch through TCM 1 (1997-10-15 through 1997-11-14). Data for satellites of Jupiter as found in the files jup204 and jup204-s3, are included. Spacecraft and planetary data come from the file 000331R_SK_LP0_V1P32, produced by the Cassini NAV group. co_1997319_99311_i_cru_v1.bsp is a merged solar system body and spacecraft trajectories covering the Interplanetary Cruise phase (1997-11-15 through 1999-11-07). Data for satellites of Jupiter, as found in the files jup204 and jup204-s3, are included. Spacecraft and planetary data come from the files 000331R_SK_LP0_V1P32, 000331RB_SK_V1P32_V2P12 and 010420R_SCPSE_EP1_JP83, produced by the Cassini NAV group. co_1999312_01066_o_cru_v1.bsp is a merged solar system body and spacecraft trajectories covering most of the Outer Cruise phase (1999-11-08 to 2001-03-07). Data for satellites of Jupiter as found in the file jup204 are included. Spacecraft and planetary data come from the file 010420R_SCPSE_EP1_JP83, produced by the Cassini NAV group. The original spacecraft trajectory files, from which the above merged files were made, were produced using a special planetary ephemeris file that was merged with the appropriate spacecraft kernel. These planetary ephemerides are to be used only in conjunction with this spacecraft ephemeris. OPS SPK files, produced by the CASSINI NAV team, named as follows: [DeliveryDate][V][T]_[Description]_[StartEvent]_[EndEvent].bsp [DeliveryDate]RU_[Description]_[StartEvent]_[EndEvent].bsp where: [DeliveryDate] Approximate date that the file was delivered (YYMMDD); [V] File version (optional, used only when applicable). It is specified as consecutive letters ``A'', ``B'', ``C'', etc. for each corresponding new version of the same file. [T] Type of the data in the file (optional, used only when applicable). If present, it is a single letter indicating predict trajectory file (``P'') or reconstructed trajectory file (``R''). [Description] File description. This field can be ``RE'' for minor satellite ephemeris SPK file, ``IRRE'' for outer irregular satellite ephemeris SPK file, or ``SCPSE'' for a merged S/C, Planetary and Satellite Ephemerides file. [StartEvent] Identifier of the file coverage start event. This field is a string consisting of two elements, , and , where represents the last two digits of the year in which the event started and is the day of the year. [EndEvent] Identifier of the file coverage end event. This field follows the same rules as the [StartEvent] field. For example, the file: 040901AP_SK_04192_05058.bsp is a binary SPK file delivered on 040901 (Sept. 1, 2004). It is the first version (A) of a Predicted SPK file covering from 2004 doy 192 to 2005 doy 058. Note that a few reconstructed trajectory files included in the archive were released in 2005-2006 with incorrect names. They had the version ([V]) and type ([T]) tokens swapped. These files are: 050105RB_SCPSE_04247_04336.bsp 050414RB_SCPSE_05034_05060.bsp 050513RB_SCPSE_05097_05114.bsp 061129RB_SCPSE_06292_06308.bsp The SPKs with the designation ``RU'' in place of the ``[V][T]'' tokens contain the Cassini trajectory reconstruction generated as part of the Uniform Trajectory Reconstruction task performed by the CASSINI NAV team after the end of the mission in 2018. In contrary to the expectations, the initial feedback from some science teams suggested that this uniform reconstruction was not better than the reconstruction done during operations. After consultations with the CASSINI NAV team it was decided to include these SPKs into the archive anyway, for the record, but to not use them in the archive meta-kernels. Special Saturnian satellites ephemeris SPKs, provided by NAIF: sat359_97288_04003.bsp is an SPK containing ephemerides for the first 10 Saturnian satellites for the period from launch to start of 2004, after which this data becomes available in the *R_SCPSE* SPKs. sat138.bsp is an older SPK containing ephemerides for the outer irregular satellites. This file is superseded by the latest *IRRE* SPK. sat427.bsp is an SPK containing ephemerides for selected Saturnian satellites, consistent with the final CASSINI reconstruction SPKs 200128RU_SCPSE_*.bsp produced by R.A. Jacobson. While data for Saturnian system included in this SPK is identical to the final CASSINI reconstruction SPKs, the ephemerides for Saturn barycenter, Sun, Earth barycenter and Earth are slightly different because they come from a more recent planetary ephemeris DE438. These SPKs do not contain any data for the CASSINI spacecraft. 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 Cassini 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 address: Navigation and Ancillary Information Facility (NAIF) Jet Propulsion Laboratory MS 301-125L 4800 Oak Grove Drive Pasadena CA 91109 USA