Mars rotation determination from a moving rover using Doppler tracking data: What could be done?

Abstract This paper is a case study providing some insights on what improvement could be achieved on the Mars Orientation and rotation Parameters (MOP) determination using radio tracking data from a moving rover. Thanks to high-performance mobility systems onboard new generation of rovers like ExoMars 2020, the position of the rover can be precisely known with respect to its previous position. This characteristic, together with the long life of the rovers and their steerable high-gain-antenna communication system, is shown here to provide an unexpected opportunity to improve the MOP determination. This paper presents the results of numerical simulations involving radio-science experiments between the moving rover and the Earth ground stations as well as between the rover and an orbiting spacecraft. The benefits of combining both links (direct-to-Earth and rover-orbiter) for the MOP determination is also assessed. The impacts of the spacecraft position accuracy as well as the frequency band used to communicate with it are quantified. It is shown that, after one Martian year of operation, the polar motion could be determined with 5 milliarcsecond (mas) of precision (formal error) from the rover-orbiter Doppler link, while it cannot be determined with usual equatorial lander-to-Earth radio link. This would allow for the first time the direct detection of the Chandler wobble amplitude in the polar motion of Mars, which is an important quantity to constrain the planet interior and atmospheric models. Although the moving rover Doppler data alone barely improve the current precision on the other MOP (like the length-of-day and nutation), a combination of those together with historical and future lander data would definitely help to fill gaps in the MOP signal and to decorrelate between the estimated parameters, thereby reducing the uncertainties in their determination.

[1]  V. Dehant,et al.  Link between the retrograde-prograde nutations and nutations in obliquity and longitude , 1995 .

[2]  L. Sebastien.  InSight coordinates determination from direct-to-Earth radio-tracking and Mars topography model , 2016 .

[3]  M. Zuber,et al.  Mars high resolution gravity fields from MRO, Mars seasonal gravity, and other dynamical parameters , 2011 .

[4]  Véronique Dehant,et al.  New constraints on Mars rotation determined from radiometric tracking of the Opportunity Mars Exploration Rover , 2014 .

[5]  V. Dehant,et al.  Lander radio science experiment with a direct link between Mars and the Earth , 2012 .

[6]  W. Folkner,et al.  Interior structure and seasonal mass redistribution of Mars from radio tracking of Mars Pathfinder. , 1997, Science.

[7]  Sami W. Asmar,et al.  The Rotation and Interior Structure Experiment on the InSight Mission to Mars , 2018, Space Science Reviews.

[8]  Sami W. Asmar,et al.  Mars reconnaissance orbiter radio science gravity investigation , 2007 .

[9]  F. Roosbeek.  Analytical developments of rigid Mars nutation and tide generating potential series , 1999 .

[10]  J. Barriot,et al.  Analytical modeling of the Doppler tracking between a lander and a Mars orbiter in terms of rotational dynamics , 2003 .

[11]  S. L. Maistre.  The rotation of Mars and Phobos from Earth-based radio-tracking observations of a lander , 2013 .

[12]  J. G. Williams,et al.  Same beam interferometry as a tool for the investigation of the lunar interior , 2012 .

[13]  V. Dehant,et al.  Signatures of the Martian rotation parameters in the Doppler and range observables , 2016, 1611.09040.

[14]  V. Dehant,et al.  Chandler wobble and Free Core Nutation for Mars , 2000 .

[15]  G. Balmino,et al.  Martian gravity field model and its time variations from MGS and Odyssey data , 2009 .

[16]  W. Folkner,et al.  The netlander ionosphere and geodesy experiment , 2001 .

[17]  G. Balmino,et al.  Lander radioscience for obtaining the rotation and orientation of Mars , 2009 .

[18]  V. Dehant,et al.  Sensitivity of the Free Core Nutation and the Chandler Wobble to changes in the interior structure of Mars , 2000 .

[19]  Dah-Ning Yuan,et al.  A global solution for the Mars static and seasonal gravity, Mars orientation, Phobos and Deimos masses, and Mars ephemeris , 2006 .

[20]  A. Rivoldini,et al.  Interior Structure and Evolution of Mars , 2014 .

[21]  S. Larsen,et al.  NETWORK SCIENCE LANDERS FOR MARS , 1999 .

[22]  J. Barriot,et al.  Numerical simulations of a Mars geodesy network experiment: Effect of orbiter angular momentum desaturation on Mars' rotation estimation , 2004 .

[23]  F. Hourdin,et al.  Influence of the seasonal winds and the CO2 mass exchange between atmosphere and polar caps on Mars' rotation , 2002 .

[24]  The Rotation of the Terrestrial Planets , 2007 .

[25]  William M. Folkner,et al.  An improved JPL Mars gravity field and orientation from Mars orbiter and lander tracking data , 2016 .