MEX models files
===========================================================================

     This ``aareadme.txt'' file describes the contents of the misc/models
     directory of the Mars-Express SPICE data server.

     It was last modified on March 23th, 2020 by Alfredo Escalante Lopez,
     ESAC/ESA.


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

     If you have any questions regarding this directory or its
     contents, please contact the ESA SPICE Service at ESAC:

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

             Alfredo Escalante Lopez
             (+34) 91-8131-429
             aescalante@sciops.esa.int, esa_spice@sciops.esa.int


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

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

     2. ``DS-Kernel Required Reading'', NAIF Document


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

     This directory contains the OBJ files with materials (MTL)
     used for generating the SPICE DS-Kernel files for the MEX
     spacecraft.

     The dimensions are in kilometers as in the DSK files and the
     center of each file correspond to the ephemeris object associated
     to the corresponding DSK center. In the same way, they OBJ models
     are oriented according to the reference frame associated to the
     corresponding DSK.


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

   Mars-Express spacecraft OBJ:

      The naming scheme for the Mars-Express spacecraft OBJ is:

           MEX_BODY_[STRUC]_vNN.obj

      where

           BODY    spacecraft/model/body identifier:

                       sc: for the MEX spacecraft

           STRUC   instrument/structure/sensor identifier (optional):

                       bus: for the MEX spacecraft bus;
                       sa: for the solar array;

           NN        OBJ version number -- 2 digits (required).


   If multiple versions of a OBJ file are provided, always use the latest
   version (unless earlier version is needed for some special reasons.)


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

     aareadme.txt                         This file.

     MEX_BODY_[STRUC]_vNN.mtl             Each OBJ has an associated MTL
                                          material file to be used in render
                                          applications.

     MEX_BODY_[STRUC]_vNN.png             Each DSK has an image example in png
                                          format for convenience.

     textures                             This subdirectory contains the
                                          textures (albedo, normal) of the
                                          parts referenced in the MTL files.


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

   Up until the expansion of SPICE with the DTM capabilities, these checks
   were performed by defining “engineering” field-of-views for these
   instruments, using the location of each of these sensors within the
   spacecraft and the corner points of the spacecraft bus and solar panels.
   This was a complex modeling, which in some cases was not feasible due to
   the type of frames of interest or illumination sources' nature.

   With the new DTM capabilities, and by modeling the BepiColombo S/Cs as an
   irregularly shaped extended ephemerides object, it is possible to exploit
   the full capabilities of the DTM subsystem to find out whether these
   conditions are met or not given a particular attitude profile of the
   spacecraft at a given time.


End of aareadme file.