The Determination of the Rotational State and Interior Structure of Venus with VERITAS

G Cascioli,S Hensley,P Racioppa,F De Marchi,D Breuer,D Durante,L Iess,S E Smrekar,E Mazarico

doi:10.3847/psj/ac26c0

Abstract

Abstract Understanding the processes that led Venus to its current state and will drive its future evolution is a major objective of the next generation of orbiters. In this work we analyze the retrieval of the spin vector, the tidal response, and the moment of inertia of Venus with VERITAS, a NASA Discovery-class mission. By simulating a systematic joint analysis of Doppler tracking data and tie points provided by the onboard synthetic aperture radar, we show that VERITAS will provide accuracies (3σ) in the estimates of the tidal Love number k 2 to 4.6 × 10−4, its tidal phase lag to 0.°05, and the moment of inertia factor to 9.8 × 10−4 (0.3% of the expected value). Applying these results to recent models of the Venus interior, we show that VERITAS will provide much-improved constraints on the interior structure of the planet.

Highlights

The most comprehensive mapping of Venus was done by the Magellan mission in the early 1990s (Saunders et al 1992)
Alongside a typical orbit determination solution employing Earth Doppler tracking data, we explore a novel approach based on the systematic inclusion of VISAR landmark features observations, or tie points, to tighten the determination of the rotational state of the planet
The inclusion of VISAR tie point measurements in the orbit determination enables a large improvement in the determination of the rotational state of Venus, not attainable with Doppler data alone

Summary

Introduction

The most comprehensive mapping of Venus was done by the Magellan mission in the early 1990s (Saunders et al 1992). The Magellan estimates, proved not sufficiently precise to constrain the structure of the mantle and core. Models of Venus’s interior relied solely on scaling Earth’s interior structure to Venus’s radius (e.g., Yoder 1995; Aitta 2012). A recent direct (ground-based) measurement of the moment of inertia factor (MOIF = C/MR2, where C is the polar moment of inertia and M and R are the planetary mass and radius, respectively) yields 7% fractional uncertainty and provides weak constraints on the internal density profile and core size (Margot et al 2021). Improved measurements are needed to quantify the interior structure of Venus with precision

Objectives

Results

Conclusion