Overview

The Venus Climate Orbiter SPICE archive contains observation geometry and other ancillary data in the form of SPICE kernels for the Venus Climate Orbiter (VCO, also known as PLANET-C and AKATSUKI) spacecraft, its instruments, and targets.

Contents

SPICE kernels

Note that the contents in this section is copied from " vco-v-spice-6-v1.0/vcosp_1000/catalog/spiceds.cat " and " vco-v-spice-6-v1.0/vcosp_1000/extras/mk/mkinfo.txt ".

CK

Five kinds of C-kernel files are provided in this archive: the reconstructed CKs for spacecraft attitude produced from telemetry, the predicted CKs for spacecraft attitude produced by data extracted from history of commands sent from the ground, the reconstructed CKs for orientation of the solar array paddles of the spacecraft produced from telemetry, the nominal CK for orientation of the solar array paddles of the spacecraft, and the predicted CKs for orientation of the two medium gain antennas of the spacecraft produced from history of commands sent from the ground. Each of these kinds is briefly described below; more information is available in the file ``data/ck/ckinfo.txt''.

All reconstructed CK files were produced from engineering telemetry downlinked from the spacecraft. As is often the case with spacecraft engineering telemetry-based measurements, considerable uncertainty exists as to the accuracy of such measurements, and, data quality (accuracy and completeness) can vary significantly.

All predicted CKs were produced from command history that describes commands sent from the ground.

Spacecraft Bus reconstructed CK Files

These CK files providing the orientation of the spacecraft bus (``vco_YYYY_vVV.bc'') can be used to support interpretation of data obtained by all science experiments. They were generated by mission operations at variable sampling resolutions depending on downlink availability and spacecraft configuration (can be up to 0.5 Hz).

Spacecraft Bus predicted CK Files

These CK files providing the orientation of the spacecraft bus (``vco_YYYY_pred_vVV.bc'') can be used to support interpretation of data obtained by all science experiments. They were generated from history of attitude control commands. These CK files cover the gaps (i.e., the period without any data points) in the reconstructed CK files for spacecraft attitude.

Solar Array Paddle Orientation reconstructed CK Files

These CK files (``vco_sap_YYYY_vVV.bc'') contain the orientation of the -Y to +Y solar array paddle (SAP1) and the +Y to -Y solar array paddle (SAP2) relative to the spacecraft bus. They were generated by mission operations at variable sampling resolutions depending on downlink availability and spacecraft configuration (can be up to 0.5 Hz).

Solar Array Paddle Nominal Orientation CK Files

These CK files (``vco_sap_nominal_vVV.bc'') contain the nominal orientation of the SAP1 and the SAP2 relative to the dynamic frame, ``VCO_SAP_NOMINAL''.

X-band Medium Gain Antennas Orientation reconstructed CK Files

These CK files (``vco_xmga_YYYY_vVV.bc'') contain the orientation of the X-band Medium Gain Antenna A (XMGA-A) and the X-band Medium Gain Antenna B (XMGA-B) relative to the spacecraft bus. They were generated from history of commands.

EK

The PLANET-C Project Team did not produce any EK files; therefore, no EKs are included in this data set.

FK

The FK files included in this data set provide definitions for the Venus Climate Orbiter spacecraft frames, and the Venus body-fixed frame. Comments in the FK files provide the frame specifications, descriptions of the frame relationships, the source of and accuracy of the mounting alignment information, etc.

The ``vco_spacecraft_vVV.tf'' FK defines the Venus Climate Orbiter spacecraft frame and frames for its engineering structures and science instruments.

The ``rssd0002.tf'' FK is the generic frames definition kernel for ESA planetary missions and defines the body-fixed frame for Venus.

Additional information about FK files provided in this data set is available in the file ``data/fk/fkinfo.txt''.

IK

The IK files included in this data set provide specifications for the optical and physical instrument parameters and -- where applicable -- field-of-view size, shape and orientation for the Venus Climate Orbiter instruments. Each IK file contains comments providing descriptions of the included parameters and FOV and frame specifications.

All IK files provided in the data set were created by the PLANET-C Project Team. There is one IK for each instrument (``vco_uvi_vVV.ti'', ``vco_ir1_vVV.ti'', ``vco_ir2_vVV.ti'', ``vco_lac_vVV.ti'', and ``vco_lir_vVV.ti'') except for Ultra Stable Oscillator (USO) used in Radio Science (RS) experiments.

Additional information about IK files provided in this data set is available in the file ``data/ik/ikinfo.txt''.

LSK

The LSK file included in this data set provides the most current tabulation of ``leapseconds'' and other terms used in converting time measurements between ephemeris time (ET) and Universal Time (UTC) at the time when this data set was assembled (February 2017).

Metadata describing how the LSK data are obtained or computed is contained inside the LSK text file. The time conversion provided by SPICE LSK files is accurate to approximately 0.000030 seconds.

Additional information about LSK files provided in this data set is available in the file ``data/lsk/lskinfo.txt''.

PCK

The PCK files included in this data set provide size, shape and orientation data for the mission target, Venus, and for the Solar System planets and satellites. A description of these data items and reference to their source is provided inside the PCK files, which are simple text files that can be viewed using any word processor, text editor or text display utility.

Two types of PCK file are provided in this data set: a type of the generic PCK file (``pck00010.tpc'') containing the official IAU/IAG/COSPAR values as of 10/21/2011 and a type containing a the Venus Climate Orbiter mission specific file (``vco_gm_de431_v01.tpc'') for the GM values used in the Venus a Climate Orbiter mission. It contains both the generic PCK provided by NAIF and the Venus Climate Orbiter mission specific parameters.

Additional information about PCK files provided in this data set is available in the file ``data/pck/pckinfo.txt''.

SCLK

The SCLK file included in this data set provides a tabulation of data needed to convert time measurements between ephemeris time (ET) and Venus Climate Orbiter spacecraft clock time (SCLK). This file was created by the PLANET-C Project Team and is named ``vco_vVV.tsc''. The accuracy of and issues with the correlation provided by this file are discussed in the comments.

Additional information about SCLK files provided in this data set is available in the file ``data/sclk/sclkinfo.txt''.

SPK

Two kinds of SPK files are provided in this archive: a planetary ephemeris SPK, spacecraft reference trajectory SPKs. Each of these kinds is briefly described below; more information is available in the file ``data/spk/spkinfo.txt''.

Planetary SPK

A custom version of planetary ephemeris SPK file containing data from both DE423 and DE430, spk/vco_de423_de430.bsp, is included in this archive.

Spacecraft Reference Trajectory SPKs

These SPKs are the latest official reference trajectory SPK files that contain only the spacecraft ephemeris. They were created by merging a series of reconstructions. These files include extensive internal comments providing detailed information.

Additional information about SPK files provided in this data set is available in the file ``data/spk/spkinfo.txt''.

Orbit number files

The orbit number files generated at the archive preparation time using the NAIF's ORBNUM utility program for the NAV SPK files covering the orbital phases of the mission are provided. These files are provided in the ``extras/orbnum'' directory.

For more information about the orbit number files, see the file ``extras/orbnum/orbinfo.txt''.

Meta-kernel files

The meta-kernel files (a.k.a "furnsh" files) that provide lists of the archived kernels included in this Venus Climate Orbiter (VCO, also known as PLANET-C and AKATSUKI) data set suitable for loading into a SPICE-based application via the high level SPICE data loader routine FURNSH are provided. Using these meta-kernels makes it easy to load with one call a comprehensive SPICE data collection for the whole mission. Like the text kernels archived in this data set, these meta-kernels are UNIX text files that have lines terminated with a line feed character, LF (ASCII 10).

The names of the meta-kernels provided in this directory follow this pattern: vco_vVV.tm where ``VV'' is the file version.

Multiple versions of a meta-kernel may exist if new kernels were added to the archive in a later release and the meta-kernel 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 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.

Although the meta-kernels were created such that on a UNIX workstation they can be loaded into a SPICE-based application directly from the root directory of the data set -- because the PATH_VALUES keyword is set to './data' 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 data set's 'data' 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.

Data Processing tools

Citation

When you publish your own work based on the Venus Climate Orbiter (AKATSUKI) SPICE kernels dataset, please refer to the following paper(s):

  1. 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.

Related Papers

Old pages

Contacts

For questions concerning this archive and the data:

Shin-ya Murakami, Japan Aerospace Exploration Agency, murashin _AT_ gfd-dennou.org
Yukio Yamamoto, Japan Aerospace Exploration Agency, yukio _AT_ planeta.sci.isas.jaxa.jp