BMAN20
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. Celest Mech Dyn Astr 132, 47 (2020)
BMAN20.1
BMAN20.1 is an update of BMAN20 that includes the following corrections:
- The four long-period terms of the original series are removed because their effect is included in the precession terms.
- The series is now scaled to the precession rate of Mars by Konopliv et al. (2016), but expressed with respect to the mean orbit of J2000 instead of the Mars mean orbit of 1980.
- Terms with period close to the ter and semi-annual periods are now merged with the main ter and semi-annual terms.
- Terms with the same periods but due to different physical causes (indirect and direct effects of Jupiter, Venus, and of the Earth) are now merged.
- Quadratic and Poisson terms in alpha/delta are corrected
- The obliquity epoch value now includes a correction of -1.4 mas, corresponding to the constant term of the nutations series used in Konopliv et al. (2016).
With a truncation criterion of 0.025 milliarcseconds in prograde and/or retrograde amplitude, we now identify 31 nutation terms.
Given the current determination of the precession rate (-7607.6118+/-2.1 mas/yr, Konopliv et al. 2016, with respect to the mean orbit of J2000), our model predicts a dynamical flattening
HD=0.00537968+/-0.00000148 and a normalized polar moment of inertia C/ MR2=0.36370+/-0.00010 for Mars.
BMAN20RS.1.RISE is a modified version of the model, which reproduces at best the behavior of the BMAN20 solution around the 16th of August 2020, the mean epoch of the RISE mission.
BMAN20RS.1.VIKING is a modified version of the model, which reproduces at best the behavior of the BMAN20 solution around the 10th of October 1977, the mean epoch of the VIKING mission.
Like BMAN20RS, BMAN20RS.1.RISE and BMAN20RS.1.VIKING group 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
BMAN20.1.PM.Ext is the series for the Polar motion induced by the external gravitational torque, provided as a byproduct of the nutation theory
Contact : rose-marie.baland@oma.be
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Nutations in longitude and in obliquity, as a function of time (in years past J2000).
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