KPL/PCK P_constants (PCK) SPICE kernel file mars_konopliv_2026_v1.tpc =========================================================================== By: Nat Bachman (NAIF) 2026 October 3 PCK for Mars rotation, based on data from the 2026 publication by Konopliv et al. [1]. To assist with PCK interoperability, rotation data for Phobos and Deimos, and triaxial ellipsoid shape models for all three bodies, are included. These data are from sources [2] and [3]. This kernel was created with the assistance of Claude Sonnet 5. Sources and References -------------------------------------------------------- Sources and background references for the constants listed in this file are: [1] Alex. S. Konopliv, Ryan S. Park, Sebastien Le Maistre, Marie Yseboodt, and Rose-Marie Baland, "Updated Mars Orientation and Gravity Field and Indication of Decadal Changes in Rotation Rate." The Planetary Science Journal, 2026, DOI: 10.3847/PSJ/ae9ba7. [2] Archinal, B.A., Acton, C.H., A'Hearn, M.F., Conrad, A., Consolmagno, G.J., Duxbury, T., Hestroffer, D., Hilton, J.L., Kirk, R.L., Klioner, S.A., McCarthy, D., Meech, K., Oberst, J., Ping, J., Seidelmann, P.K., Tholen, D.J., Thomas, P.C., and Williams, I.P., "Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015," Celestial Mechanics and Dynamical Astronomy 130, Article number 22 (2018). DOI: https://doi.org/10.1007/s10569-017-9805-5 [3] Archinal, B.A., Acton, C.H., Conrad, A., Duxbury, T., Hestroffer, D., Hilton, J.L., Jorda, L., Kirk, R.L., Klioner, S.A., Margot, J.-L., Meech, K., Oberst, J., Paganelli, F., Ping, J., Seidelmann, P.K., Stark, A., Tholen, D.J., Wang, Y., and Williams, I.P., "Correction to: Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015." Rotation data for Phobos and Deimos, and triaxial ellipsoid radii for all three bodies, are included. These data are from [2] and [3]. Toolkit Compatibility Warning -------------------------------------------------------- This file provides Mars system rotation data usable with the N0067 and newer versions of the SPICE Toolkit. This file cannot be used to compute Mars, Phobos, or Deimos orientation with Toolkit versions N0066 or earlier versions. See "Software Limitations" below. All other data are compatible with the N0066 and earlier Toolkits. NAIF provides the PCK file mars_konopliv_2026_n0066_v1.tpc for use with older Toolkits. That PCK contains all the data from this file, except that, in that file, one of the phase angle polynomials for Phobos is truncated to first order. Software Limitations -------------------------------------------------------- SPICE support for quadratic phase angle polynomials was introduced in the N0067 Toolkit version. Older Toolkits cannot make use of the Mars system orientation data provided in this file. Older Toolkits are unable to detect and signal a SPICE error if they are used to compute orientation of Mars, Phobos, or Deimos using these data: memory corruption will occur in user applications linked to these Toolkits if the applications attempt such computations. Any results, including those of unrelated computations, may be invalid after such memory corruption occurs. See the NAIF server at https://naif.jpl.nasa.gov for the file mars_konopliv_2026_n0066_v1.tpc, which can be used with older Toolkits. Kernel Interoperability -------------------------------------------------------- This PCK file can be safely loaded after other, older generic text PCKs created by NAIF. Loading it before these or other text PCKs may prevent use of Mars system rotation models from those files. PCK incompatibility can be due to kernel variables defined by this PCK and not overwritten by PCKs loaded later. This problem can be resolved in two ways: 1) After using this kernel, unload it before loading incompatible PCKs. 2) After using this kernel, load the PCK mars_rotation_reset_v1.tpc before loading incompatible PCKs. Loading that file after this PCK has been used, and before another PCK is loaded, enables Mars system rotation models from the last-loaded PCK to function properly. See the documentation within mars_rotation_reset_v1.tpc for details. Data Modifications -------------------------------------------------------- 1) Poisson terms in the angular expressions for alpha, delta, and W in the source model have been replaced by asymptotic approximations, in order to represent the expressions in a format compatible with SPICE Toolkit software. The approximation replaces expressions of the form T * sin ( a + b * T ) T * cos ( a + b * T ) with, respectively, sums of expressions of the form constant * scale * sin( T / scale ) * sin ( a + b * T ) constant * scale * sin( T / scale ) * cos ( a + b * T ) Here T represents Julian centuries past J2000 TDB, and scale = 1.0e4 The modified expressions agree with the original ones, over the time range 1970-2050, to these levels: Maximum absolute alpha error (rad) = 5.33e-15 Maximum absolute delta error (rad) = 6.66e-16 Maximum absolute W error (rad) = 1.09e-10 These errors were determined by sampling using a step size of approximately 250 seconds. The modified expressions have been analytically transformed to expressions that satisfy SPICE text PCK requirements. 2) A typo in a constant in pck00011.tpc has been corrected. The quadratic coefficient in the 5th Mars system phase angle has been set to 12.71192322 replacing the value from pck00011.tpc 12.711923222 Data -------------------------------------------------------- \begintext The first set of angle coefficients below are those supporting rotation models for Phobos and Deimos. Later assignments in this file augment the angle set with data used by the Mars rotation model. \begindata BODY4_MAX_PHASE_DEGREE = 2 BODY4_NUT_PREC_ANGLES = ( 190.72646643 15917.10818695 0 21.46892470 31834.27934054 0 332.86082793 19139.89694742 0 394.93256437 38280.79631835 0 189.63271560 41215158.18420050 12.71192322 121.46893664 660.22803474 0 231.05028581 660.99123540 0 251.37314025 1320.50145245 0 217.98635955 38279.96125550 0 196.19729402 19139.83628608 0 198.991226 19139.4819985 0 226.292679 38280.8511281 0 249.663391 57420.7251593 0 266.183510 76560.6367950 0 79.398797 0.5042615 0 122.433576 19139.9407476 0 43.058401 38280.8753272 0 57.663379 57420.7517205 0 79.476401 76560.6495004 0 166.325722 0.5042615 0 129.071773 19140.0328244 0 36.352167 38281.0473591 0 56.668646 57420.9295360 0 67.364003 76560.2552215 0 104.792680 95700.4387578 0 95.391654 0.5042615 0 ) \begintext Polynomial terms of expressions for Mars pole RA, pole Dec, and prime meridian angle W. \begindata BODY499_POLE_RA = ( 317.6811001 -0.1085514 -2.99e-5 ) BODY499_POLE_DEC = ( 52.8863461 -0.0614879 4.41e-5 ) BODY499_PM = ( 176.6302669 350.89198247002 -8.5e-15 ) \begintext Nutation precession angles for Mars pole RA: \begindata BODY4_NUT_PREC_ANGLES += ( 226.3 38280.6 0 198.6 19140.3 0 248.7 57420.9 0 266.0 76561.2 0 194.7 15924.9 0 285.2 95701.5 0 305.1 657.5 0 304.5 114841.8 0 59.2 38280.594270422051 0 239.2 38280.605729577946 0 210.7 19140.294270422048 0 30.7 19140.305729577951 0 ) \begintext Nutation precession angles for Mars pole Dec: \begindata BODY4_NUT_PREC_ANGLES += ( 43.0 38280.6 0 122.7 19140.3 0 58.7 57420.9 0 79.8 76561.2 0 194.7 15924.9 0 99.3 95701.5 0 305.1 657.5 0 118.7 114841.8 0 80.8 19140.294270422048 0 260.8 19140.305729577951 0 212.3 38280.594270422051 0 32.3 38280.605729577946 0 ) \begintext Nutation precession angles for Mars prime meridian angle W: \begindata BODY4_NUT_PREC_ANGLES += ( 46.3 38280.6 0 147.5 19139.9 0 92.6 1395.3 0 18.6 19140.3 0 253.3 38279.7 0 68.7 57420.9 0 86.0 76561.2 0 291.9 57419.6 0 237.1 76559.4 0 14.7 15924.9 0 105.2 95701.5 0 125.1 657.5 0 321.0 16105.3 0 124.5 114841.8 0 27.6 19140.294270422048 0 207.6 19140.305729577951 0 247.7 38280.594270422051 0 67.7 38280.605729577946 0 ) \begintext Nutation precession angle coefficients for Mars pole RA: \begindata BODY499_NUT_PREC_RA = ( 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) BODY499_NUT_PREC_RA += ( 0.0002383 0.0000682 0.0000519 0.0000088 0.0000019 0.0000014 0.0000007 0.0000002 0.006 0.006 0.005 0.005 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) \begintext Nutation precession angle coefficients for Mars pole Dec: \begindata BODY499_NUT_PREC_DEC = ( 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) BODY499_NUT_PREC_DEC += ( 0 0 0 0 0 0 0 0 0 0 0 0 0.0001414 0.0000519 0.0000310 0.0000053 0.0000012 0.0000008 0.0000004 0.0000001 0.002 0.002 0.004 0.004 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) \begintext Nutation precession angle coefficients for Mars prime meridian angle W: \begindata BODY499_NUT_PREC_PM = ( 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) BODY499_NUT_PREC_PM += ( 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0001900 0.0001448 0.0000683 0.0000544 0.0000467 0.0000414 0.0000070 0.0000055 0.0000030 0.0000015 0.0000011 0.0000006 0.0000002 0.0000002 0.004 0.004 0.005 0.005 ) \begintext Rotation data for Phobos and Deimos follow. Satellites of Mars Phobos Old values are from the 2009 IAU report. body401_pole_ra = ( 317.68 -0.108 0. ) body401_pole_dec = ( 52.90 -0.061 0. ) body401_pm = ( 35.06 1128.8445850 6.6443009930565219e-09 ) body401_long_axis = ( 0. ) body401_nut_prec_ra = ( 1.79 0. 0. 0. ) body401_nut_prec_dec = ( -1.08 0. 0. 0. ) body401_nut_prec_pm = ( -1.42 -0.78 0. 0. ) The quadratic prime meridian term is scaled by 1/36525**2: 8.864000000000000 ---> 6.6443009930565219E-09 Current values: Values from the 2015 IAU report [2] were corrected by [3], which is used as the source for the data below. The quadratic prime meridian term is scaled by 1/36525**2: 12.72192797000000000000 ---> 9.536137031212154e-09 \begindata BODY401_POLE_RA = ( 317.67071657 -0.10844326 0. ) BODY401_POLE_DEC = ( 52.88627266 -0.06134706 0. ) BODY401_PM = ( 35.18774440 1128.84475928 9.536137031212154e-09 ) BODY401_LONG_AXIS = ( 0. ) BODY401_NUT_PREC_RA = ( -1.78428399 0.02212824 -0.01028251 -0.00475595 ) BODY401_NUT_PREC_DEC = ( -1.07516537 0.00668626 -0.00648740 0.00281576 ) BODY401_NUT_PREC_PM = ( 1.42421769 -0.02273783 0.00410711 0.00631964 -1.143 ) \begintext Deimos Old values are from the 2009 IAU report. The Deimos prime meridian expression from that report is: 2 W = 79.41 + 285.1618970 d - 0.520 T - 2.58 sin M 3 + 0.19 cos M . 3 At the present time, the PCK kernel software (the routine BODEUL in particular) cannot handle the cosine term directly, but we can represent it as 0.19 sin M 4 where M = 90.D0 - M 4 3 Therefore, the old nutation precession angle assignments for Phobos and Deimos contain four coefficients rather than three. The quadratic prime meridian term is scaled by 1/36525**2: -0.5200000000000000 ---> -3.8978300049519307E-10 body402_pole_ra = ( 316.65 -0.108 0. ) body402_pole_dec = ( 53.52 -0.061 0. ) body402_pm = ( 79.41 285.1618970 -3.897830d-10 ) body402_long_axis = ( 0. ) body402_nut_prec_ra = ( 0. 0. 2.98 0. ) body402_nut_prec_dec = ( 0. 0. -1.78 0. ) body402_nut_prec_pm = ( 0. 0. -2.58 0.19 ) New values: \begindata BODY402_POLE_RA = ( 316.65705808 -0.10518014 0. ) BODY402_POLE_DEC = ( 53.50992033 -0.05979094 0. ) BODY402_PM = ( 79.39932954 285.16188899 0. ) BODY402_LONG_AXIS = ( 0. ) BODY402_NUT_PREC_RA = ( 0 0 0 0 0 3.09217726 0.22980637 0.06418655 0.02533537 0.00778695 ) BODY402_NUT_PREC_DEC = ( 0 0 0 0 0 1.83936004 0.14325320 0.01911409 -0.01482590 0.00192430 ) BODY402_NUT_PREC_PM = ( 0 0 0 0 0 -2.73954829 -0.39968606 -0.06563259 -0.02912940 0.01699160 ) \begintext Radii of Mars System Objects -------------------------------------------------------- Values are from [2]. Mars \begindata BODY499_RADII = ( 3396.19 3396.19 3376.20 ) \begintext Phobos \begindata BODY401_RADII = ( 13.0 11.4 9.1 ) \begintext Deimos \begindata BODY402_RADII = ( 7.8 6.0 5.1 ) \begintext =========================================================================== End of file mars_konopliv_2026_v1.tpc ===========================================================================