PDS_VERSION_ID                = PDS3
RECORD_TYPE                   = STREAM
OBJECT                        = TEXT
  NOTE                        = "Comments on the Venus Climate Orbiter
SPICE Data Archive"
  PUBLICATION_DATE            = 2021-04-28
END_OBJECT                    = TEXT
END


COMMENTS ON THE VENUS CLIMATE ORBITER SPICE DATA ARCHIVE
========================================================

   This document contains comments and errata concerning the Venus
   Climate Orbiter (VCO, also known as PLANET-C and AKATSUKI) SPICE
   Data Archive.

   This data set is superseded by the PDS4 Venus Climate Orbiter
   Akatsuki SPICE kernel archive.


1. Text Kernel File Format
--------------------------

   All SPICE text kernel files (LSK, PCK, SCLK, IK, FK) provided in
   these volumes have lines terminated by only <LF> (UNIX convention.)
   This is dictated by NAIF's archiving approach to include a
   consistent set of UNIX binary (IEEE architecture) and text (<LF>
   only for end of line marker) kernels in the archive volumes.

   However, the format of the text kernels is specified in their
   associated labels as ASCII (INTERCHANGE_FORMAT = ASCII.) This is a
   violation of the PDS standard stating that lines in ASCII files must
   be delimited by the combination of <CR><LF>. This line termination
   treatment is standard practice for SPICE volumes in the PDS.


2. Use of SPACECRAFT_NAME in the Labels
---------------------------------------

   PDS labels for SPICE kernels provided in this data set contain the
   deprecated keyword SPACECRAFT_NAME instead of the keyword
   INSTRUMENT_HOST_NAME. This is standard practice for SPICE volumes in
   the PDS and is dictated by NAIF's archiving approach to make SPICE
   archives for more recent missions consistent with SPICE archives for
   older missions, for which use of SPACECRAFT_NAME was legitimate.


3. Values of INSTRUMENT_NAME in the Labels
------------------------------------------

   PDS labels for SPICE kernels provided in this data do not set the
   keyword INSTRUMENT_NAME to "SPICE KERNELS", that is the name of the
   instrument described by the instrument catalog file SPICE_INST.CAT
   provided in the data set. Instead this keyword is set to either
   "N/A" or the name(s) of the instrument(s) or structure(s), the
   geometric parameters of which a particular kernel file provides.
   While this error does prevent the individual data products from
   being associated with the "SPICE KERNELS" instrument, it does not
   affect usability of the SPICE data provided in this data set in any
   way because the SPICE Toolkit does not use any information from the
   PDS label to access the data.


4. Missing FILE_RECORDS Keyword in the Binary Kernel Labels
-----------------------------------------------------------

   All labels for binary SPICE kernels provided in this data set are
   missing the FILE_RECORDS keyword, which is required because these
   labels have the RECORD_TYPE keyword set to FIXED_LENGTH. While this
   error violates the PDS standards, it does not affect usability of
   the SPICE data provided in this data set in any way because the
   SPICE Toolkit does not use any information from the PDS labels to
   access the data.


5. Target Catalog Files
-----------------------------------------------------------

   No target catalog files are provided in this data set. The catalog
   files for the targets listed in the "mission.cat" are assumed to have
   already been ingested from the Venus Climate Orbiter science data sets.


6. Bad Version 1 XMGA CKs
-------------------------

   The version 1 XMGA CKs covering from January 2011 to December 2012,
   added to the data set in the release 1 provided erroneous data during
   September 2011 to April 2012.

   The version 2 XMGA CKs covering the same time interval, added to the
   data set in the release 2 fully supersede the version 1 CKs. They fix
   the errors found in the version 1 CKs.


7. Bad Version 2 S/C and SAP CKs for year 2018
----------------------------------------------

   The version 2 S/C and SAP CKs for year 2018 added to the data set in
   the release 3 contain erroneous data points.

   The version 3 S/C and SAP CKs for year 2018 added to the data set in
   the release 4 fully supersede the version 2 CKs for year 2018. The
   erroneous data points are excluded from these updated CKs found in
   the version 2 CKs.


8. Meta-data updates for PDS3 to PDS4 migration
-----------------------------------------------

   The release 5 of this archive has been amended by updating the
   "spiceds.cat" catalog file, "aareadme.txt", "aareadme.htm", and
   "errata.txt" files to indicate that the data set has been superseded
   by the PDS4 Venus Climate Orbiter Akatsuki SPICE kernel archive.