EnVision MK files
===========================================================================

     This ``aareadme.txt'' file describes the contents of the kernels/spk
     directory of the EnVision SPICE data server.

     It was last modified on February 24, 2025 by Alfredo Escalante Lopez,
     ESAC/ESA.


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

             Alfredo Escalante Lopez
             (+34) 91-8131-429
             spice@cosmos.esa.int

     or NAIF at JPL:

             Boris Semenov
             (818) 354-8136
             Boris.Semenov@jpl.nasa.gov

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

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


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

     This directory contains the SPICE Meta-Kernel files for the EnVision
     mission. Meta-kernels (also known as ``FURNSH kernel'') are used to 
     name a collection of kernels that are to be loaded into a user's 
     application at run-time. Meta-kernels are appropiate to group kernels
     that correspond to a certain study group, phase or kernel state of the
     mission.


File naming conventions
--------------------------------------------------------

   Naming Scheme for EnVision spacecraft MKs:
   
     The naming scheme for the EnVision spacecraft MKs is:
     
           envision[_ID][_DESC][_TAG][vNNN].tm
           
     where

           ID        mapping to the original trajectory file product IDs 
                     as defined per the original Mission Analysis filename 
                     (optional) e.g.:

           DESC      a brief description of the scope of study of the 
                     trajectory (optional);

           TAG       a time tag of the MK generation time (optional; 
                     e.g. 20160928);
                 
           vNNN      version number that corresponds to the current SPICE
                     kernel dataset release (optional; e.g. v100);
           

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

     aareadme.txt         This file.
   
     former_versions      Directory where versions no longer valid are
                          stored for archive purposes.



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

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

     EnVision has a number of meta-kernels that contain information of the
     so-called crema document; these are trajectories provided by Mission
     Analysis for the development phase. These meta-kernels are used for
     studies and development.


Kernel File Details
--------------------------------------------------------

    Name                            Comments
    ---------------------------------------------------------------------

    envision_study_ID.tm            Contains the latest version of the
                                    information defined by the Study scenario
                                    described by ID.

    envision_study_ID_vXXX[_YYYYMMDD_NNN].tm

                                    Is a duplicate of the study MK that
                                    derived from ID. If multiple operational MK
                                    files are generated on the same date the
                                    version NNN is increased starting from 001.
                                    The YYYYMMDD_NNN tag is optional.


End of aareadme file.