The precession and nutations of a rigid Mars


  • BMAN20 (Baland Martian Analytical Nutations 2020) is a semi-analytical model to predict the precession and nutations of a rigid Mars, based on the Torque approach. It is an update of RMAN99 (Roosbeek, 1999). We include in the BMAN20 model the torques by the Sun, Phobos, Deimos, and the other planets of the Solar System. We also include the geodetic precession and nutations. With a truncation criterion of 0.025 milliarcseconds in prograde and/or retrograde amplitude, we identify 43 nutation terms. The uncertainty on our solution (0.03%) mainly derives from the observational uncertainty on the current determination of the precession rate of Mars by Konopliv et al. (2016). Uncertainties related to our modeling choices are negligible in comparison.
  • Given the current determination of the precession rate (7608.3+/-2.1 mas/yr, Konopliv et al. 2016), our model predicts a dynamical flattening HD=0.00538017+/-0.00000148 and a normalized polar moment of inertia C/ MR2=0.36367+/-0.00010 for Mars.
  • BMAN20RS (BMAN20 for Radio Science) is a modified version of the model, which reproduces at best the behavior of the BMAN20 solution around J2022, the average epoch of the RISE and LaRa mission duration, but groups different terms (main periodic terms, Poisson terms, and periodic terms of period close to the period of the main periodic terms) into a more limited subset of nutation terms that can be observed and identified by the radioscience instruments LaRa and RISE onboard the ExoMars and InSight missions.
  • RMAN99 recomputed is a modern recomputation of RMAN99 nutation series.
  • Citation : Baland, R.-M., Yseboodt, M., Le Maistre, S., Rivoldini, A., Van Hoolst, T., and Dehant, V., The precession and nutations of a rigid Mars: Analytical developments, CMDA, submitted.

    Contact :

    Nutations in longitude and in obliquity, as a function of time (in years past J2000).


    1. Files :
      1. bman20.dat : Periodic and Poisson terms of the rigid Mars nutation series BMAN20
      2. bman20rs.dat : Periodic terms of the rigid Mars nutation series BMAN20RS
      3. bman20_TimesSeries.dat : times series obtained from BMAN20
      4. bman20rs_TimesSeries.dat : times series obtained from BMAN20RS
      5. bman20.txt : readme file for bman20.dat and bman20rs.dat
      6. rman99_recomputed.dat : Periodic terms of the recomputation of the rigid Mars nutation series of RMAN99 (Roosbeek 1999)
      7. rman99_recomputed_TimesSeries.dat : times series obtained from RMAN99 recomputed
      8. rman99_recomputed.txt : readme file for rman99_recomputed.dat