A new look at Venus gravity and rotation from a reanalysis of Magellan Doppler tracking

Most of the current knowledge regarding the interior of Venus is derived from Magellan gravity and topography datasets collected three decades ago. While this mission provided the first high-resolution global gravity field, the computational limitations of the 1990s necessitated compromises that impacted the accuracy of the gravity solutions. We report on a reanalysis of the Magellan Doppler tracking data, leveraging modern computational capabilities to improve the Venus gravity field, orientation, and rotational dynamics.

Most significantly, modern computing power allows us to achieve a spherical harmonic degree-and-order 180 solution via a single inversion, eliminating the need for the multi-step approach that previously affected the solution.  We observe a reduction in high-frequency noise (ringing) in the solution, leading to more coherent spatial structures in the solution which is beneficial for localized analyses of near-subsurface features. The single-step solution, additionally, removes the discontinuities in the uncertainty estimates of the gravity field coefficients, enabling more coherent and robust uncertainty quantification on derived products.

Using this new field, we investigate the elastic properties of the lithosphere taking advantage of improved polar resolution and robust uncertainty quantification. Additionally, we assess the sensitivity of the dataset to length-of-day variations which were previously not explicitly solved-for, but whose magnitudes as observed from Earth would have had a measurable influence on the probe.