The DART SPICE Data Archive
========================================================================

   Last update: December 4, 2023


Introduction
============

   This document describes the DART SPICE archive, containing
   observation geometry and other ancillary data in the form of SPICE
   System kernel files for the DART spacecraft and its instruments and
   targets, and for the LICIACube (LICIA) spacecraft and its instruments and
   structures. It describes the archive directory structure, kernels
   included in the archive, their naming conventions, and provides
   pointers to the SPICE software and documentation.


Table of Contents
=================

   Introduction
   Table of Contents
   Overview
   Errata
   Archive Contents
   Kernel Types
   Archived Kernel Details
      SPK Files
      PCK Files
      IK Files
      CK Files
      LSK Files
      SCLK Files
      FK Files
      DSK Files
      MK Files
   Miscellaneous Files
      Checksum Files
   File Formats
   SPICE Software and Documentation
   Contact Information
   Cognizant Persons



Overview
========

   This archive includes the complete set of DART and LICIA SPICE data
   files (kernel files), which can be accessed using SPICE software. The
   SPICE data contain geometric and other ancillary information needed
   to recover the full value of science instrument data. In particular
   SPICE kernels provide spacecraft and planetary ephemerides, spacecraft
   and instrument orientation, instrument mounting alignments, and data
   needed for relevant time conversions. Data in the SPICE kernel files
   must be accessed using the software called the SPICE Toolkit produced
   and distributed by the Navigation and Ancillary Information Facility
   (NAIF) Node of the Planetary Data System.

   This archive includes data covering from DART launch, 2021-11-18,
   through the end time of the latest spacecraft orientation file
   supplied in the archive. Until the end of the spacecraft lifespan
   this archive will be accumulating with new data added according to
   the project archiving plan.

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Errata ====== 1. This document is a simple HTML document. Providing documents in a simple mark-up format was allowed by earlier versions of the PDS4 Standards but became prohibited in later versions starting summer 2015. Since using HTML documents was compliant at the time when a similar document was first provided in the MAVEN PDS4 archive and since NAIF strives to make bundle description document format and style consistent across all archives, this document continues to exist in this archive as an HTML document. 2. The XML labels of the ancillary products have the reference_type attribute of the Internal_Reference association within the Reference_List class of the Context_Area class pointing to the latest archive description document set to "ancillary_to_data" which is not correct. The correct value "ancillary_to_document" could not be used in these labels because it is not available in the PDS4 information model (IM) 1.5.0.0 used by this archive. This value was added to IM only in the version 1.14.0.0. 3. CK files generated for the DART spacecraft contain several gaps in time coverage for different known reasons. These gaps may be eliminated in the next release. 4. SPK file didymos_system_s501_v01.bsp has a 1 ms gap in coverage at the time of impact. This gap is eliminated in didymos_system_s542_v01.bsp. 5. The SPK dart_2022_231_2022_269_rec_v01.bsp, reconstructed from telemetry, and the SPK dart_2022_269_2022_269_spc_v01.bsp, reconstructed from Stereophotoclinometry, differ by approximately 2.7 km down-track distance and 0.45 seconds at the impact time of 2022-09-26T23:14:24.183 UTC. This version of the _rec_ SPK did not consider the final four hours of imaging, but future versions will include them. 6. The impact time according to SPK dart_2022_269_2022_269_spc_v01.bsp is 2022-SEP-26 23:14:24.164 UTC. This was found by determining the closest approach of DART to the impact site SPK dart_2022_269_2099_001_imp_v01.bsp. This differs from the impact time of 2022-SEP-26 23:14:24.183 UTC from dart_2022_269_2022_269_spc_v01.bsp and didymos_system_s501_v01.bsp by ~19 milliseconds. Most, but not all, of this discrepancy is the travel time of DART from the surface of Dimorphos to its center. 7. Version 003 of the Dimorphos DSK files had incorrect surface names listed in the "Objects" section. For example: The DSK surface NAIF ID code is DART_DIMORPHOS_000250MM_SPC_V003 should have read The DSK surface name is DART_DIMORPHOS_00250MM_SPC_V003 This issue is fixed for Didymos DSK files V003 and Dimorphos DSK files V004. 8. There is a ~72 cm offset between the final position of DART from dart_2022_269_2022_269_spc_v04.bsp and the impact position from dart_2022_269_2099_001_imp_v03.bsp. 9. DSK file names have five digits for the resolution. The source OBJ files for the v003 DSK files for Didymos and v004 DSK files for Dimorphos use 4 digits for the resolution. For example, didymos_g_09309mm_spc_0000n00000_v003.bds was built from didymos_g_9309mm_spc_obj_0000n00000_v003.obj, available at the PDS. Its surface name is DART_DIDYMOS_09309MM_SPC_V003. 10. The dart_spice archive coverage was set based on label values from text kernels. However, the actual coverage of the dart_spice archive based on DART and LICIA SPK and CK coverage is 2021-11-24T07:16:44 - 2023-03-31T23:58:51

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Archive Contents =============== Files in this archive are organized into a set of subdirectories below the top-level directory. The following diagram shows the structure and content of these directories. The directory names are enclosed in square brackets ([]). [top-level-directory] | |- bundle_dart_spice_v*.xml Bundle PDS4 label, one or more versions. |- readme.txt Bundle top-level readme file. | |-[spice_kernels] Directory containing SPICE kernels. | | | |- collection_spice_kernels_v*.xml PDS4 labels for Spice Kernels collections. | |- collection_spice_kernels_inventory_v*.tab | | Spice Kernels collections' inventories. | | | |-[ck] Directory containing CK files. | | | | | |-- *.bc Binary CK files. | | +-- *.xml PDS4 labels for CK files. | | | |-[dsk] Directory containing DSK files. | | | | | |-- *.bds Binary DSK files. | | +-- *.xml PDS4 labels for DSK files. | | | |-[fk] Directory containing FK files. | | | | | |-- *.tf Text FK files. | | +-- *.xml PDS4 labels for FK files. | | | |-[ik] Directory containing IK files. | | | | | |-- *.ti Text IK files. | | +-- *.xml PDS4 labels for IK files. | | | |-[lsk] Directory containing LSK files. | | | | | |-- *.tls Text LSK files. | | +-- *.xml PDS4 labels for LSK files. | | | |--[mk] Directory containing MK files. | | | | | |-- *.tm Text Meta-kernel files. | | +-- *.xml PDS4 labels for MK files. | | | |-[pck] Directory containing PCK files. | | | | | |-- *.tpc Text PCK files. | | +-- *.xml PDS4 labels for PCK files. | | | |-[sclk] Directory containing SCLK files. | | | | | |-- *.tsc Text SCLK files. | | +-- *.xml PDS4 labels for SCLK files. | | | +-[spk] Directory containing SPK files. | | | |-- *.bsp Binary SPK files. | +-- *.xml PDS4 labels for SPK files. | |-+-[miscellaneous] Directory miscellaneous files. | | | |- collection_miscellaneous_v*.xml PDS4 labels for miscellaneous collections. | |- collection_miscellaneous_inventory_v*.tab | | Miscellaneous collections' inventories. | | | +-[checksum] Directory containing checksum files. | | | |-- *.tab Text checksum files. | +-- *.xml PDS4 labels for checksum files. | +-[document] Directory containing documents. | |- collection_document_v*.xml PDS4 labels for document collections. |- collection_document_inventory_v*.tab | Document collections' inventories. | |- spiceds_v*.html This file and its earlier versions. +- spiceds_v*.xml PDS4 labels for this file and its earlier versions.

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Kernel Types ============ Different SPICE kernel types are used to store different kinds of ancillary data. SPK (Spacecraft Planet Kernel) files contain ephemerides (position and velocity) for spacecraft, planets, satellites, comets and asteroids as well as for moving or fixed spacecraft and instrument structures. SPK files are located under the spice_kernels/spk directory of this archive. PCK (Planetary Constants Kernel) files contain certain physical, dynamical and cartographic constants for target bodies, such as size and shape specifications, and orientation of the spin axis and prime meridian. PCK files are located under the spice_kernels/pck directory of this archive. IK (Instrument Kernel) files contain instrument parameters relevant for computing an instrument's geometry such as field-of-view definitions, CCD and optical distortion characteristics, and internal timing parameters. IK files are located under the spice_kernels/ik directory of this archive. CK (C-matrix Kernel) files contain time varying orientations for spacecraft, spacecraft structures, and articulating science instruments. CK files are located under the spice_kernels/ck directory of this archive. LSK (Leapseconds Kernel) files contain the leapseconds and the values of other constants required to perform a transformation between Universal Time Coordinated (UTC) and Ephemeris time (ET), which is also known as Barycentric Dynamical Time (TDB). LSK files are located under the spice_kernels/lsk directory of this archive. SCLK (Spacecraft Clock Kernel) files contain on-board clock calibration data required to perform a transformation between Ephemeris time (ET) and spacecraft on-board time (SCLK). SCLK files are located under the spice_kernels/sclk directory of this archive. FK (Frame definitions Kernel) files contain information required to define reference frames, sources of frame orientation data and connections between these frames and other frames supported within the SPICE system. The science instrument frame definitions provided in the FK files include mounting alignment information for the instruments. FK files also frequently contain NAIF name/ID mappings for bodies, spacecraft instruments and structures, and for DSK surfaces. FK files are located under the spice_kernels/fk directory of this archive. DSK (Digital Shape Kernel) files contain detailed shape models for extended objects such as planets, natural satellites, asteroids, and comet nuclei. DSK files are located under the spice_kernels/dsk directory of this archive. MK (Meta-Kernel) files list sets of related SPICE kernels that should be used together, providing an easy way to make data from these kernel sets available to a SPICE-based application by loading meta-kernels into the program using the high level SPICE data loader routine FURNSH. MK files are located under the spice_kernels/mk directory of this archive. Archived Kernel Details ======================= The subsections below provide details, such as file naming conventions and specific details, for each of the kernel types included in this archive.

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SPK Files SPK (Spacecraft Planet Kernel) files contain ephemerides (position and velocity) for spacecraft, planets, satellites, comets and asteroids as well as for moving or fixed spacecraft and instrument structures. This archive includes binary SPK files containing the following kinds of ephemeris data: - planetary ephemeris SPKs These SPKs contain ephemeris data for the Solar System planet barycenters, and Sun, Mercury, Venus, Earth, and Moon. They are produced by the JPL Solar System Dynamics group and are named DEXXX, e.g. DE424. - Asteroids Didymos and Dimorphos ephemeris SPKs These SPKs contain ephemeris data for the Didymos System. They are produced by the JPL Solar System Dynamics group. - DART structure SPK SPK containing fixed structures on the DART spacecraft (e.g. solar arrays, LICIACube mount, thrusters). - reconstructed spacecraft trajectory SPKs. These SPKs contain the reconstructed DART spacecraft trajectory determined by the DART Mission Design Team. The SPK files are provided under the spice_kernels/spk directory and are named according to the following schemes: - planetary ephemeris SPKs deVVVs.bsp where VVV is the ephemeris version s (optional) indicates that the original file coverage was shortened to reduce the file size. - Jovian system ephemeris SPKs jupVVV.bsp where VVV is the ephemeris version. - Didymos system ephemeris SPKs didymos_barycenter_sSSS_vVV.bsp where SSS is the solution version. VV is the file version; the file with the latest version supersedes all similarly named files with earlier versions. - Didymos and Dimorphos ephemeris SPKs didymos_system_sSSS_vVV.bsp where SSS is the solution version. VV is the file version; the file with the latest version supersedes all similarly named files with earlier versions. - DART structure SPK dart_struct_vVV.bsp where VV is the file version; the file with the latest version supersedes all similarly named files with earlier versions. - reconstructed trajectory SPKs SC_YYYY_DDD_YYYY_DDD_TYPE_vVV.bsp where SC is the spacecraft name, either "dart" or "licia". YYYY is the file coverage start and stop year DDD is the file coverage start and stop day of year TYPE is the data type imp impact kernel; this is the fixed position of the DART impact site on Dimorphos rec reconstructed trajectory spc derived from stereophotoclinometry VV is the version; the file with the latest version supersedes all similarly named files with earlier versions. 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 program COMMNT included in the NAIF Toolkit.

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PCK Files PCK (Planetary Constants Kernel) files contain certain physical, dynamical, and cartographic constants for target bodies, such as size and shape specifications, and orientation of the spin axis and prime meridian. This archive includes text and binary PCK files containing the following kind of data: - generic text PCKs These PCKs contain data from the reports of the IAU Working Group on Cartographic Coordinates and Rotational Elements. The generic text PCK version 00010 contains data from the 2009 report. Produced by NAIF, JPL. - Didymos system text PCK files These PCKs contain for the Didymos system provided by the DART science team. The PCK files are provided under the spice_kernels/pck directory and are named according to the following schemas: - generic text PCKs pckVVVVV.tpc where VVVVV is the version; the file with the largest number is the latest, but the user of PCK data must decide if the latest version, or an earlier version, is appropriate for his/her analysis task. - Didymos system text PCK files didymos_system_VV.tpc where VV is the file version; the file with the latest version supersedes all similarly named files with earlier versions. The most detailed description of the data in a text PCK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program.

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IK Files IK (Instrument Kernel) files contain instrument parameters relevant for computing an instrument's observation geometry such as field-of-view definitions, CCD and optical distortion characteristics, and internal timing parameters. This archive includes text IK files for the DRACO camera on board DART and for the Luke and Leia cameras on board LICIA. The IK files are provided under the spice_kernels/ik directory and are named according to the following scheme: - instrument and antennae IK files SC_NAME_VVV.ti where SC is the spacecraft name, either "dart" or "licia". NAME is the instrument acronym: draco Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO) pl LICIA Luke and Leia combined payload VVV is the version; the file with the latest version supersedes all similarly named files with earlier versions. The most detailed description of the data in a text IK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program.

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CK Files CK (C-matrix Kernel) files contain time varying orientations for spacecraft, articulating spacecraft structures, and articulating science instruments. This archive includes binary CK files containing the following kinds of orientation data: - DART spacecraft, high gain antenna, and solar array CKs and These CKs contain reconstructed and predicted DART spacecraft solar arrays, and high gain antenna orientation information. - LICIA spacecraft CKs These CKs contain reconstructed and predicted LICIA spacecraft orientation information. The CK files are provided under the spice_kernels/ck directory and are named according to the following scheme: - DART spacecraft, high gain antenna, and solar array CKs and LICIA spacecraft CKs SC_YYYY_DDD_YYYY_DDD_TYPE_vVV.bc where SC is the spacecraft name, either "dart" or "licia". YYYY is the start/end year DDD is the start/end day of year TYPE is the data type rec reconstructed attitude from telemetry spc derived from stereophotoclinometry VV is the version; the file with the latest version supersedes all similarly named files with earlier versions. The most detailed description of the data in each CK file is provided in metadata included inside the comment area of the file. This information can be viewed using the utility program COMMNT included in the NAIF Toolkit.

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LSK Files LSK (Leapseconds Kernel) files contain the leapseconds and the values of other constants required to perform a transformation between Universal Time Coordinated (UTC) and Ephemeris time (ET), also known as Barycentric Dynamical Time (TDB). This archive includes generic text LSK files produced by NAIF, containing leapsecond information based on the IERS announcements. The LSK files are provided under the spice_kernels/lsk directory and are named according to the following scheme: - generic text LSKs naifVVVV.tls where VVVV is the version; the file with the latest version supersedes all similarly named files with earlier versions. The most detailed description of the data in a text LSK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program.

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SCLK Files SCLK (Spacecraft Clock Kernel) files contain on-board clock calibration data required to perform a mapping between Ephemeris time (ET) and spacecraft on-board time (SCLK). This archive includes text SCLK files containing correlation data for the main DART on-board clock and the LICIA on-board clock. The SCLK files are provided under the spice_kernels/sclk directory and are named according to the following scheme: - spacecraft clock SCLK files SC_sclk_VVVV.tsc where SC is the name of the spacecraft in lower case; either "dart" or "licia" VVVV is the version; the file with the latest version supersedes all similarly named files with earlier versions. The most detailed description of the data in a text SCLK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program.

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FK Files FK (Frame definitions Kernel) files contain information required to define reference frames, sources of frame orientation data and connections between these frames and other frames supported within the SPICE system. The science instrument frame definitions provided in the FK files include mounting alignment information for the instruments. This archive includes text FK files defining reference frames for the DART spacecraft, its structures, and science instruments. These FKs were produced by NAIF using the spacecraft and instrument design documentation as well as actual instrument alignment values determined pre-launch and as the result of in-flight calibrations. It also includes text FK files defining reference frames and surface name/ID mappings for the Didymos system. The FK files are provided under the spice_kernels/fk directory and are named according to the following scheme: - Spacecraft FK files SC_VVV.tf where SC is the name of the spacecraft in lower case; either "dart" or "licia" VVV is the version; the file with the latest version supersedes all similarly named files with earlier versions, although a SPICE user might decide decide to use an earlier version if trying to be consistent with some earlier computed results. - Didymos system FK files didymos_system_VVV.tf where VVV is the version; the file with the latest version supersedes all similarly named files with earlier versions, although a SPICE user might decide decide to use an earlier version if trying to be consistent with some earlier computed results. The most detailed description of the data in a text FK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program.

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DSK Files DSK (Digital Shape Kernel) files contain detailed shape models for extended objects such as planets, natural satellites, asteroids, and comet nuclei. This archive includes binary DSK files containing digital shape data for the DART mission target asteroids Didymos and Dimorphos. These DSKs were produced by the DART Altimetry Working Group. The DSK files are provided under the spice_kernels/dsk directory and are named according to the following scheme: - asteroid Didymos/Dimorphos DSK files BODY_C_RRRRRmm_spc_LLLLDGGGGG_vVVV.bds where BODY is the body name in lower case; either "didymos" or "dimorphos" C is the spatial coverage token: g global coverage; if the file contains a complete closed body surface l local (partial) coverage; if the single file contains only a part of the a complete body surface, whether as part of a global tileset or just a small disjoint region RRRRR is the average vertex spacing, in mm SSS is the shape model source: spc stereophotoclinometry LLLLD is the center latitude of the file LLLL latitude in degrees; implicit decimal point after the second digit; D n for North or s for South; 0000n for files with global coverage GGGGG is the center longitude of the file; in degrees; implicit decimal point after the third digit; 00000 for files with global coverage VVV version number. The most detailed description of the data in each DSK file is provided in metadata included inside the comment area of the file. This information can be viewed using the utility program COMMNT included in the NAIF Toolkit.

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MK Files Meta-kernel (MK) files (a.k.a 'furnsh' files) provide lists of the archived kernels included in this archive suitable for loading into a SPICE-based application via the high level SPICE data loader routine FURNSH. Using meta-kernels makes it easy to load, with one call, a comprehensive SPICE data collection for a given period. The text MK files are provided under the spice_kernels/mk directory and are named according to the following scheme: - DART MK files dart_vVV.tm where VV is the version; the file with the latest version supersedes all similarly named files with earlier versions. Although the meta-kernels were created such that on a UNIX workstation they can be loaded into a SPICE-based application directly from the directory in which they reside -- because the PATH_VALUES keyword is set to '..' and '/' is used as the path delimiter -- it is recommended that users make local copies of these files and update the PATH_VALUES keyword in each of them to point to the actual location of the archive's 'spice_kernels' directory on their system. Additional changes including replacing '/' and '\' in all path specifications and converting UNIX line terminators to terminators native to the user's system may be required to use these meta-kernels on non-UNIX workstation. The following guidelines were followed to pick and set priority -- determined by the order in which the kernel files are listed, with the latest one taking precedence -- for the kernel files included in the dart_vVV.tm meta-kernels: - the latest archived versions of LSK, PCK, and each kind of SCLKs, IKs, FKs, SPKs, and CKs were included - no DSKs were included Additional description of the kernels sets listed in a text MK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program.

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Miscellaneous Files =================== Miscellaneous files provide value added elements that are outside the scope of the PDS archive requirements. Miscellaneous files included in this archive are currently limited to checksum files. The subsection below provides details for these files.

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Checksum Files A checksum file provides a table of MD5 checksums for all files in the archive as of a particular archive (bundle) version, including checksums for all previous checksums files and their labels but excluding the checksum for the checksum file itself and its label. The checksum files are provided under the miscellaneous/checksum directory and are named according to the following scheme: - DART checksum files checksum_vVVV.tab where VVV is the version; the file with the latest version supersedes all similarly named files with earlier versions and can be used to validate the archive in its entirety.

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File Formats ============ All text documents, checksum files, and other meta information files such as descriptions, detached PDS4 labels, and inventory tables, are stream format files, with a carriage return (ASCII 13) and a line feed character (ASCII 10) at the end of the records. This allows the files to be read by most operating systems. The text kernel files in this archive -- LSKs, PCKs, SCLKs, IKs, FKs, and MKs -- are UNIX text files, with a line feed character (ASCII 10) at the end of the line, and binary kernel files -- SPKs, CKs, and DSKs -- are IEEE LSB binary files. While data files in this archive can be used 'as is' with SPICE toolkits for the majority of supported environments, converting the files to the binary or text format native to the user's computer may be required for use of the data with FORTRAN toolkits on incompatible environments. Refer to the documentation provided with the SPICE Toolkit to find out whether conversion is needed in each specific case. NAIF provides a tool (BINGO) that can convert either binary or text kernels from one format to another. This means that text files can have their line terminator changed and binary files can be converted to the native format of the platform of interest. BINGO is available from the utilities page at the NAIF Node of the PDS: https://naif.jpl.nasa.gov/naif/utilities.html

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SPICE Software and Documentation ================================ The latest SPICE Toolkit for a variety of computer platforms, additional utility programs, documentation, tutorials, and hands-on lessons are available at the NAIF Node of the PDS: https://naif.jpl.nasa.gov specifically: Toolkit: https://naif.jpl.nasa.gov/naif/toolkit.html Utilities: https://naif.jpl.nasa.gov/naif/utilities.html Tutorials: https://naif.jpl.nasa.gov/naif/tutorials.html Lessons: https://naif.jpl.nasa.gov/naif/lessons.html

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Contact Information =============================== PDS Navigation and Ancillary Information Facility (NAIF), MAIL STOP 301-121 Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Pasadena, CA, 91109-8099 818-354-8136 WWW Site: http://naif.jpl.nasa.gov

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Cognizant Persons ================= This archive was produced by Hari Nair, Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, Marc Costa Sitja and Alyssa Bailey, Planetary Data System Navigation and Ancillary Information Facility Node, Jet Propulsion Laboratory, Pasadena, California. End of DART SPICE archive description.

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