KPL/PCK

P_constants (PCK) SPICE kernel file mars_rotation_reset_v1.tpc
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   By: Nat Bachman (NAIF)    2026 October 3

   This kernel was created with the assistance of Claude Sonnet 5.

Purpose
--------------------------------------------------------

   This PCK can ensure that Mars and Mars satellite orientation 
   computations performed using NAIF text PCKs are not compromised by 
   residual data from other, earlier loaded, PCKs.

   The PCK files 

      mars_konopliv_2026_v1.tpc
      mars_konopliv_2026_n0066_v1.tpc
      pck00011.tpc
      pck00011_n0066.tpc

   define kernel variables that aren't necessarily overwritten 
   when other PCKs are loaded after them, during a program run.
   Below, we'll call the files listed above the "extended PCKs."

   Residual kernel variables defined by the extended PCKs may 
   prevent or corrupt computation of orientation of Mars, or of 
   Mars satellites, performed using other PCKs. 

   Orientation models that are vulnerable to the effects of these 
   residual kernel variables are those that contain Mars and Mars 
   satellite orientation data, but that do not redefine all of the 
   kernel variables of the corresponding models in the files listed 
   above. 

   We'll call PCKs containing these models the "vulnerable PCKs."

   This set of vulnerable PCKs includes older NAIF generic text PCKs,
   up to and including

      pck00010.tpc 

   Archived and operational PCKs may be vulnerable as well.
  
   Loading this kernel after loading any of the extended PCKs,
   and before loading vulnerable PCKs, eliminates this problem.

   Residual kernel variables also can be removed by unloading
   the PCKs that defined the variables. However, this is not 
   always practical, and it has the side effect of clearing 
   from the kernel pool any variables defined via the programmatic
   interface.


Applicability
--------------------------------------------------------

   This PCK addresses interoperability problems arising from 
   use of the extended PCKs listed above. 
   
   This PCK may be applicable when user applications load PCKs 
   not produced by NAIF, but which define the same kernel 
   variables as the extended PCKs, possibly using different data.


Updates 
--------------------------------------------------------

   It is possible that future Mars system PCKs will define 
   additional kernel variables that need to be reset by this 
   kernel.

   It's also possible that the list of extended PCKs produced 
   by NAIF will grow, without any change to the kernel variables 
   requiring a reset. In this case, NAIF will update the comments 
   of this file to accurately specify the set of extended PCKs.

   If the future NAIF generic text PCKs (no release date is 
   currently planned)

      pck00012.tpc 
      pck00012_n0066.tpc 

   use the Mars system rotation models of the Mars Konopliv 2026 
   PCKs, those PCKs would be added to the list of extended PCKs.
   The comments of this file would be updated to refer to them, 
   but the data assignments would not change.

   NAIF will release a new version of this file if any changes 
   are made to its data or documentation. The file name's 
   version number will be incremented. 

   NAIF requests that users who modify this file also rename it
   using a name pattern that doesn't conflict with that used 
   by NAIF. 


Usage 
--------------------------------------------------------

   This kernel may be loaded by meta-kernels, or loaded directly.
   To be effective, if loaded via a meta-kernel, it must be listed 
   in the meta-kernel's
   
      KERNELS_TO_LOAD 

   assignments ahead of any vulnerable PCKs containing Mars system
   rotation data. If loaded directly, it must be loaded ahead of
   any vulnerable PCKs.

   This kernel must not be loaded after loading the extended  
   PCKs if Mars or Mars satellite orientation data from 
   those kernels is to be used subsequently, since this kernel
   modifies the kernel variables containing those data.


   Example 1: a meta-kernel that loads this kernel prior to loading
            a "vulnerable" PCK. 

   In the text below, we've omitted from the "begindata" and "begintext"
   directives the backslash characters that would be used in an actual 
   meta-kernel.

      KPL/MK 

      We load the "reset" PCK in this meta-kernel to protect
      the Mars system rotation models of pck00010.tpc from any
      residual kernel variables defined by a PCK that may have been 
      loaded earlier.

      begindata 

         KERNELS_TO_LOAD = ( 'naif0012.tls' 
                             'mars_rotation_reset_v1.tpc'
                             'pck00010.tpc' ) 

      begintext 
      

   Example 2: a C-style pseudo-code fragment that loads a Mars 
              Konopliv 2026 PCK, then "cleans up" by loading this 
              kernel, then loads an older PCK. 

      furnsh_c( "mars_konopliv_2026_n0066_v1.tpc" );
      
      Do some work...

      /*
      Clean up residual kernel variables without unloading the 
      currently loaded PCK, then load another PCK.
      */
      furnsh_c( "mars_rotation_reset_v1.tpc" );

      furnsh_c( "pck00010.tpc" );

      Do some work...

      /*
      End of function
      */


Data
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\begindata  

   BODY4_MAX_PHASE_DEGREE = 1
   BODY4_NUT_PREC_ANGLES  = ( 0.0 0.0 )

   BODY499_NUT_PREC_RA  = 0.0
   BODY499_NUT_PREC_DEC = 0.0
   BODY499_NUT_PREC_PM  = 0.0 

\begintext

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End of file mars_rotation_reset_v1.tpc
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