Dehant, Véronique ; Le Maistre, Sébastien ; Yseboodt, Marie ; Baland, Rose-Marie ; Karatekin, Ozgur ; Péters, Marie-Julie ; Rivoldini, Attilio ; Van Hoolst, Tim ; Van Hove, Bart ; Kosov, Alexander

Poster presented at AGU, San Francisco, USA on 2019-12-11 on 2019-12-11

Abstract: The LaRa (Lander Radioscience) experiment is designed to obtain coherent two-way Doppler measurements from the radio link between the 2020 ExoMars lander (the Kazachok surface platform) and Earth during at least one Martian year. The Doppler shifts are measured by comparing the frequency of the radio signal received from LaRa with the known frequency of a ground-based reference signal. Transmitting signals from Earth to Mars and back again is called two-way communication and greatly enhances the accuracy of the radio experiment. The Doppler measurements are used to determine the orientation and rotation of Mars in space (precession, nutations, and length-of-day variations), as well as polar motion, more accurately than ever before. The LaRa transponder is designed to maintain the phase coherency of the signal, and the global precision on the Doppler measurements is expected to be better than 0.1 mm/s for a 60-second integration time (compared to instrument precision requirements at the level of 0.02 mm/s for a 60-second integration time). The final objective is to obtain new information and constraints on the interior of Mars, and on the sublimation and condensation cycle of atmospheric CO2. Rotational variations will allow us to constrain the moments of inertia of the whole planet, including its mantle and core, moments of inertia of the core only, and seasonal mass transfer between the atmosphere and ice caps. The LaRa experiment will be combined with other ExoMars experiments in order to retrieve a maximum amount of information. We will also combine LaRa’s Doppler measurements with similar data from the Viking landers, Mars Pathfinder, Mars Exploration Rovers, and the ongoing InSight/RISE mission, will provide information on the interior of Mars with unprecedented accuracy, improving our understanding of the formation and evolution of the Red Planet.

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Funding: ESA/PRODEX/PlanetInt ESA/PRODEX/LaRa