Mars precession rate determined from radiometric tracking of the InSight Lander. (May 2021) - Kahan, Daniel S.
Abstract: The Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) mission has provided an opportunity to improve our knowledge of Mars' interior via the Rotation and Interior Structure Experiment (RISE). RISE provides information on the rotation of Mars by measuring the Doppler shift of radio transmissions from InSight to NASA's Deep Space Network (DSN) on Earth. Through the combination of one year of Doppler data from InSight with previous data from the Viking-1 lander, Mars Pathfinder, and Opportunity missions, data spanning 43 years from 1976 to 2019 are used to estimate the Mars precession rate as −7605 ​± ​3 milliarcseconds per year. This result is consistent with the precession rate estimated from Doppler tracking of previous landers and orbiters alone. Highlights: The Doppler shift of signals between Mars landers and Earth tracking stations can be used to estimate Mars' rotation. One year of InSight tracking data are combined with data from Opportunity, Pathfinder, and Viking-1 to estimate Mars' precession rate. Mars' precession rate is used to compute the mean Moment of Inertia, which constrains the radius of the core.