4602 20200124121649.0 POSTER-2020-0028 Le Maistre, Sébastien First estimate of Mars precession rate and moment of inertia from data of the Rotation and Interior Structure Experiment (RISE) on the InSight Mission to Mars 2019 2019-12-09 The Rotation and Interior Structure Experiment (RISE) on-board the InSight mission uses the lander’s X-band (8 GHz) radio system in combination with tracking stations of the NASA Deep Space Network (DSN) to deduce the rotation and orientation of Mars. The determination of precession and nutation of the spin axis are the main objectives of RISE. While measuring nutation precisely requires accumulating data over almost a Martian year, the precession rate can already be determined after one Earth year of operations with better accuracy than today. Here we present the improved precession rate and the associated moment of inertia of Mars. We compare it with the results based on other spacecraft and we discuss the constraints implied by this new value on the interior structure of the planet. PRODEX/ PRODEX/ PRODEX NO Folkner, William Rivoldini, Attilio Dehant, Veronique M A Yseboodt, Marie Van Hoolst, Tim Kahan, Daniel S Buccino, Dustin AGU fall meeting, San Francisco, USA marie.yseboodt@observatoire.be https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/574764 CPOSTER