The Venus Climate Orbiter Akatsuki SPICE Data Archive
=======================================================================

  Last update: June 7, 2023


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

   This document describes the Venus Climate Orbiter (VCO, also
   known as PLANET-C and AKATSUKI) SPICE archive, containing
   observation geometry and other ancillary data in the form of SPICE
   System kernel files for the Venus Climate Orbiter Akatsuki spacecraft
   and its instruments and targets. 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
      MK Files
   Miscellaneous Files
      Checksum Files
      Orbit Number Files
   File Formats
   SPICE Software and Documentation
   Contact Information
   Cognizant Persons



Overview
========

   This archive includes the complete set of VCO 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 VCO launch, 2010-05-20,
   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.

   This archive supersedes the Venus Climate Orbiter PDS3 data set:

      Murakami, S., Y. Yamamoto, K. McGouldrick, G. L. Hashimoto,
      N. Hirata, VENUS CLIMATE ORBITER SPICE KERNELS V1.0,
      VCO-V-SPICE-6-V1.0, NASA Planetary Data System, 2017.
      https://doi.org/10.17597/isas.darts/vco-00001

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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 the document was compliant at the time when its first version was released, it will continue to exist in the archive as an HTML document. 2. Some of the SPICE kernels present in the first release of this bundle have embedded PDS3 labels. This is intentional in order to preserve the original kernels from the PDS3 data set that this PDS4 bundle supersedes. 3. PDS4 labels vco_v0[1-6].xml for SPICE text orbit number files vco_v0[1-6].orb released as part of the bundle version 1.0 have wrong offset value in the Table_Character class. It has 365 but the correct value is 363. In Header class in the labels, object_length also have wrong value which is 364 but the correct value is 363.

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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_vco_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. | | | |-[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. | | | +-[orbnum] Directory containing orbit number files. | | | |-- *.orb Text orbit number files. | +-- *.xml PDS4 labels for orbit number 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, detector 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 are located under the spice_kernels/fk 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 the spice_kernels/mk directory of this archive.

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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 under the spice_kernels/spk directory (Only the leading portions of the file names are shown; the file name extensions of the binary SPK files are always ``.bsp''): vco_YYYY_vVV SPK files containing the trajectory of the Venus Climate Orbiter Akatsuki spacecraft relative to the Sun or Venus barycenter, mostly created during operations by the ISAS orbit determination group, JAXA. Most of source data for 2010 and for some periods around orbital maneuvers in 2015 were created by the NASA JPL Navigation Team. YYYY in the file name that represents the year identify the period covered by the file. vco_de423_de430 vco_de423_de430 combined planetary ephemeris SPK containing data from both de423 and de430. This kernel contains the results of merging portions of DE423 with DE430, to produce a single SPK file that should be valid for the bulk of the entire Venus Climate Orbiter Akatsuki mission. If this data set contains multiple SPK files for a particular period, the one with the latest version (VV) supersedes all previous 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 (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. The PCK files are provided under the spice_kernels/pck directory (Only file names are shown; the file name extensions of the text PCK kernel files are always ``.tpc''): vco_gm_de431_vVV PCK file containing mass parameters used in the Venus Climate Orbiter Akatsuki mission. This file is based on gm_de431.tpc, created by NAIF, and then modified only GM values for Venus and Venus barycenter, where VV is the version number. pck00010 generic PCK file containing IAU 2009 rotation and shape constants for planets, satellites, and some asteroids, created by NAIF. If this data set contains multiple PCK files, the one with the latest version (VV) supersedes all previous versions. In most cases these two PCK files pck00010.tpc vco_gm_de431_vVV.tpc should be loaded into a user's application to process data for the science phase(s) of the mission. 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 (Instrument Kernel) files contain instrument parameters relevant for computing an instrument's observation geometry such field-of-view definitions, detector and optical distortion characteristics, and internal timing parameters. The following IK files are provided under the spice_kernels/ik directory (only the leading portion of the file name is shown; the extension of all file names is ``.ti''): vco_ir1_vVV IK file containing FOV and reference frame definitions for the VCO 1-MICRON camera (IR1) instrument, created by the PLANET-C IR1 Team. vco_ir2_vVV IK file containing FOV and reference frame definitions for the VCO 2-MICRON camera (IR2) instrument, created by the PLANET-C IR2 Team. vco_lac_vVV IK file containing FOV and reference frame definitions for the VCO Lightning and Airglow Camera (LAC) instrument, created by the PLANET-C LAC Team. vco_lir_vVV IK file containing FOV and reference frame definitions for the VCO Longwave Infrared Camera (LIR) instrument, created by the PLANET-C LIR Team. vco_uvi_vVV IK file containing FOV and reference frame definitions for the VCO Ultra Violet Imager (UVI) instrument, created by the PLANET-C UVI Team. If this data set contains multiple IK files for a particular instrument, the one with the latest version (VV) supersedes all previous versions. In most cases these IK files vco_ir1_vVV.ti vco_ir2_vVV.ti vco_lac_vVV.ti vco_lir_vVV.ti vco_uvi_vVV.ti should be loaded into a user's application to process data for the science phase(s) of the mission. 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 under th spice_kernels/ck directory and are named according to the following scheme: The following CK files are provided in the spice_kernels/ck directory (only the leading portion of the file name is shown; the extension of all CK file names is ``.bc''): vco_YYYY_vVV CK files containing reconstructed Venus Climate Orbiter Akatsuki spacecraft orientation, created during operations by the PLANET-C Project Team. YYYY in the file name that represents the year identify the period covered by the file and VV is the version number. vco_YYYY_pred_vVV CK files containing predicted orientation of the Venus Climate Orbiter Akatsuki spacecraft, covering only ``gaps'', i.e., periods without data in the yearly reconstructed CK files, vco_YYYY_vVV, created by the PLANET-C Project Team. YYYY in the file name that represents the year identify the period covered by the file and VV is the version number. For the case of YYYY with 2012 and 2013, there aren't any gaps in the reconstructed CKs, so the predicted CKs for 2012 and 2013 don't exist. vco_sap_nominal_vVV CK files containing two Solar Array Paddles' orientation of the Venus Climate Orbiter Akatsuki spacecraft, with respect to the dynamic frame named ``VCO_SAP_NOMINAL''. VV in the file name is the version number. vco_sap_YYYY_vVV CK files containing two Solar Array Paddles' orientation of the Venus Climate Orbiter Akatsuki spacecraft, with respect to the Venus Climate Orbiter Akatsuki spacecraft body-fixed frame, created by the PLANET-C Project Team. YYYY in the file name that represents the year identify the period covered by the file and VV is the version number. vco_xmga_YYYY_vVV CK files containing two X-band Medium Gain Antennas' orientation of the Venus Climate Orbiter Akatsuki spacecraft, with respect to the Venus Climate Orbiter Akatsuki spacecraft body-fixed frame, created by the PLANET-C Project Team. YYYY in the file name that represents the year identify the period covered by the file and VV is the version number. If this data set contains multiple CK files for a particular period, the one with the latest version (VV) supersedes all previous versions. In most cases these CK files vco_YYYY_pred_vVV.bc vco_YYYY_vVV.bc vco_sap_nominal_vVV.bc vco_sap_YYYY_vVV.bc vco_xmga_YYYY_vVV.bc should be loaded in this order into a user's application to process data for the mission. 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 following LSK file is provided under the spice_kernels/lsk directory: naifVVVV.tls where VVVV is the file version. The latest LSK file supersedes all previous 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). The following Frames Kernel files are provided under the spice_kernels/sclk directory (only the leading portion of the file name is shown; the extension of all file names is ``.tsc''): vco_vVV SCLK file containing clock correlation data for the Venus Climate Orbiter Akatsuki spacecraft on-board clock, created by the PLANET-C Project Team, where VV is the version number. If this data set contains multiple SCLK files for a particular period, the one with the latest version (VV) supersedes all previous 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. The following Frames Kernel files are provided under the spice_kernels/fk directory (only the name portion of the file name is shown on the right; the extension of all file names is ``.tf''): rssd0002 Generic Frames Definition Kernel for ESA Planetary Missions. 0002 is the version number. This file is used in the Venus Climate Orbiter Akatsuki mission to calculate orbit number for the Venus Climate Orbiter Akatsuki spacecraft. vco_spacecraft_vVV FK file containing the definition of the Venus Climate Orbiter Akatsuki spacecraft body-fixed frame and frames for its engineering structures and science instruments, created by the PLANET-C Project Team, where VV is the version number. If this data set contains multiple FK files, the one with the latest version (VV) supersedes all previous versions. In most cases both FK files should be loaded into a user's application to process data for the science phase(s) of the mission. 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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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. The text MK files are provided under the spice_kernels/mk directory follow this pattern: vco_pds4_vVV.tm where ``VV'' is the file version and ``pds4'' indicates that the text and PATH_VALUE key in meta-kernel versions 01 to 05 differ from the meta-kernels present in the superseded PDS3 data set. Multiple versions of a meta-kernel may exist if new kernels were added to the archive in a later release and the meta-kernel for that it had to be updated to incorporate them. The reasons for adding new kernels include (but are not limited to) adding new kinds of kernels, adding new versions of existing kernels containing more complete or more accurate data, and adding new versions of existing kernels superseding the existing kernels that had errors. If more than one meta-kernel file is present, then the file with the latest version number supersedes all earlier versions. (Note that on some environments loading too many kernels at once may slow down data access.) 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 these meta-kernels: - the latest archived versions of LSK and FK were included - the sets of the CKs, SPKs, PCKs, IKs, and SCLKs were picked according to the recommendations made in the corresponding sections of this document - the predicted CKs where produced for Venus Climate Orbiter Akatsuki spacecraft attitude are also included in the metakernel, listed before each reconstructed CK kernel for the spacecraft attitude. This way, the reconstructed information will have preference, and the predicted attitude will be used only for periods of time when there is no reconstructed attitude - the nominal CK where produced for solar array paddles of Venus Climate Orbiter Akatsuki spacecraft is also included in the metakernel, listed before each reconstructed CK kernel for the solar array paddles orientations. This way, the reconstructed information will have preference, and the nominal orientation will be used only for periods of time when there is no reconstructed orientation 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 and orbit number 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: checksum_vVVV.tab where ``VVV'' is the file version. The file with the latest version supersedes all files with earlier versions and can be used to validate the archive in its entirety.

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Orbit Number Files An orbit number (ORBNUM) file provides a table of records ordered by an increasing orbit numbering scheme. The orbit number changes at every periapsis event and the information contained for each record includes: - Orbit number ("No".) - Periapsis UTC time ("Event UTC PERI") - SCLK time ("Event SCLK PERI" ) - Apoapsis UTC time ("OP-Event UTC APO") - Sub-solar geodetic longitude and latitude (SolLon, SolLat), in the IAU_VENUS reference frame. - Sub-spacecraft geodetic longitude and latitude (SC Lon, SC Lat), in the IAU_VENUS reference frame. - Altitude of the vehicle above the primary body (Alt) - Inclination of the vehicle orbit (Inc) - Eccentricity of the orbit plane about the primary body (Ecc) - Longitude of the ascending node of the orbit (LonNode) - Argument of periapsis of the orbit (Arg Per) - Solar distance the time of the orbit event (Sol Dist) - Semimajor axis of the orbit (Semi Axis) All the orbital elements are calculated in the VME2000 reference frame. See rssd0002.tf for details about this frame. The ORBNUM files have been generated during the mission using the NAIF's ORBNUM utility program for consolidated spacecraft trajectory SPK files for the orbital phases of the mission. Orbit number 1 corresponds to the first orbit, started from 2015-12-07. The ORBNUM files are provided under the miscellaneous/orbnum directory and are named: vco_vVV.orb where ``VV'' is the file version. The file with the latest version supersedes all files with earlier versions. The files included in this dataset are the most recent files available at the moment of the compilation of each release of this dataset, which should span at least the same time interval as all the SPK files included in the dataset.

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File Formats ============ All text documents 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 --, the ORBNUM files, and the checksum files are UNIX text files, with a line feed character (ASCII 10) at the end of each line. Binary kernel files -- SPKs and CKs -- 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 =============================== Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA) 3-1-1 Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa 252-5210, Japan WWW Site: https://darts.isas.jaxa.jp/about.html.en Electronic mail address: darts-admin@ml.isas.jaxa.jp 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: https://naif.jpl.nasa.gov

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Cognizant Persons ================= This archive was designed and produced by Shin-ya Murakami, Yukio Yamamoto, and Kevin McGouldrick. End of Venus Climate Orbiter Akatsuki SPICE archive description.

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