Solar Orbiter MK files
===========================================================================

     This ``aareadme.txt'' file describes the contents of the kernels/mk
     directory of the Solar Orbiter SPICE Kernel Dataset.

     It was last modified on July 4, 2019 by Marc Costa Sitja, ESAC/ESA.


Brief Summary
--------------------------------------------------------

     This directory contains the SPICE Meta-Kernel files for the
     SOLAR ORBITER mission. Meta-kernels (also known as ``FURNSH kernel'')
     are a way of loading a  self-consistent dataset with a single command.
     They are essentially an ASCII file containing a list of other kernels to
     load, and are how we will manage version control: If a user has access to
     the entire Solar Orbiter SPICE Kernel Dataset and loads the most recent
     meta-kernel, they will automatically be using the most recent versions of
     each kernel.

     SOC will maintain two meta-kernels: One for the predictive dataset, and
     one for the as- flown dataset. This is necessary because of the different
     spacecraft clocks used in the production of the attitude kernels.


File naming conventions and Kernel File Details
--------------------------------------------------------

    The naming scheme for the SOLAR ORBITER MKs is:

       solo_ANC_soc-TYPE-mk[_VNNN_YYYYMMDD_XXX].tm

     where

           TYPE      Type of meta-kernel:

                        pred: predicted attitude
                        flown: as-flown attitude

           NNN       version number that corresponds to the version of the
                     meta-kernel or the SPICE Kernel Dataset release number
                     (optional, e.g. v121 for Release 1.2.1)

           YYYYMMDD  a date tag of the MK generation time (optional,
                     e.g. 20190604);

           XXX       a count of the MK version generated for a given date.
                     (optional, e.g. 001)


Other directory contents
--------------------------------------------------------

     aareadme.txt         This file.

     former_versions      Directory where old versions are stored for
                          archive and consistency purposes.


Particulars
--------------------------------------------------------

     Meta-Kernel file management is a critical element of any SPICE dataset.
     For ESA Missions the Meta-Kernels of the operational SPICE repositories
     are also used to control the version of the SPICE Kernel Dataset.

     For what concerns SPICE Kernel Dataset version kernels, they are
     generated when a new version of the kernel dataset is released.
     In parallel a new operational version is made available.

     In general missions in operations will have an "operational" Meta-Kernel.
     This MK will contain the latest SPICE kernels available for the mission
     including those kernels generated by the operational pipeline in a
     periodical basis (namely SPK, CK and SCLK files).
     Since the periodicity of this updates ranges from hours to weeks
     (should happen after every S/C Ground Station pass), the MK
     in the Meta-Kernel directory does not have a version number and is
     regularly overwritten. Nevertheless in order to keep traceability and
     backwards compatibility with former MKs, a duplicate of every generated
     MK is stored. This duplicated MK filename is appended with a time-tag and
     a version; if the original MK looks like:

        SOLAR-ORBITER/kernels/mk/solo_ANC_soc-pred-mk.tm

     the following duplicate is generated:

        SOLAR-ORBITER/kernels/mk/solo_ANC_soc-pred-mk_V100_20190704_001.tm

     New kernel datasets are typically released when new text kernels are
     added, updated or modified, when there is a change in the directory
     structure, etc. Superseded version kernels are moved to the
     'former_versions' directory.


Contact Information
--------------------------------------------------------

   If you have any questions regarding this file contact the
   ESA SPICE Service (ESS) at ESAC:

           Marc Costa Sitja
           (+34) 91-8131-457
           esa_spice@sciops.esa.int, marc.costa@esa.int

   or the Solar Orbiter Science Operations Center at ESAC:

           sol_soc@esa.int


References and required readings
--------------------------------------------------------

     1. ``Kernel Required Reading'', NAIF Document

     2. ``SOC-Provided Ancillary Data for Solar Orbiter'',
        SOL-SGS-TN-0017, A. Walsh, Issue 0, Revision 3, 22/09/2018


End of aareadme file.