PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT NOTE = "Comments on the DAWN SPICE Archive" PUBLICATION_DATE = 2019-02-22 END_OBJECT = TEXT END COMMENTS ON THE DAWN SPICE DATA ARCHIVE ====================================== This document contains comments and errata concerning the DAWN SPICE Data Archive. 1. Text Kernel File Format -------------------------- All SPICE text kernel files (LSK, PCK, SCLK, IK, FK) provided in this data set have lines terminated by only (UNIX convention.) This is dictated by NAIF's archiving approach to include a consistent set of UNIX binary (IEEE architecture) and text ( only for end of line marker) kernels in the archived data sets. 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 . This line termination treatment is standard practice for SPICE data sets 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 data sets 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. The other side of this error is that the data set does not include instrument catalog files for the following instruments named in the INSTRUMENT_NAME keyword in the PDS labels: "DAWN SPACECRAFT" "DAWN SOLAR ARRAYS" "VISIBLE INFRARED MAPPING SPECTROMETER" "GAMMA-RAY AND NEUTRON DETECTOR" "FRAMING CAMERA 1" "FRAMING CAMERA 2" 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. Changes to Already Archived Kernels and Labels ------------------------------------------------- Although NAIF archiving policies prohibit modification of any kernels or labels already released to the public, an exception to this policy was made to change the DESCRIPTION values in the detached and embedded labels for PCKs "dawn_vesta_v05.tpc" and "pck00008.tpc" to more clearly state which Vesta rotation constants these PCKs provide and to correct two minor errors in the comments in the PCK file "dawn_vesta_v06.tpc". For this reason the versions of the PCKs and detached labels provided in the archive as of release "0001" differ in DESCRIPTION values provided in the archive as of releases "0002" and later. 6. Error in SPK dawn_rec_150630-151023_151210_v1.bsp ---------------------------------------------------- The DAWN spacecraft trajectory data provided in the SPK file dawn_rec_150630-151023_151210_v1.bsp was incorrect during the interval 2015-07-24 to 2015-08-14 due to missing thrust models in the OD solution. This SPK was superseded by the SPK file dawn_rec_150630-151023_160804_v1.bsp correcting this error, added to the data set in the release 0006. 7. Error in Orbit Number file dawn_ceres_v02.nrb ------------------------------------------------ Due to erroneous spacecraft trajectory data provided in the SPK file dawn_rec_150630-151023_151210_v1.bsp for the interval 2015-07-24 to 2015-08-14, the orbit number file dawn_ceres_v02.nrb generated using that SPK had incorrect orbit start/stop times starting with the orbit 24 (2015-07-24). This orbit number file was superseded by the orbit number file dawn_ceres_v03.nrb correcting this error, added to the data set in the release 0006. 8. Use of "CERES ENCOUNTER" phase in the Labels ----------------------------------------------- For consistency with labels for kernels added to the data set in earlier, pre-Ceres releases, all labels for kernels covering the "CERES ENCOUNTER", "CERES EXTENDED MISSION 1", and "CERES EXTENDED MISSION 2" phases use only the "CERES ENCOUNTER" phase in the MISSION_PHASE_NAME keyword. End of errata.txt.