EnVision Radio Science and Altimetric Data Processing for Orbit Determination

The precise orbit determination for ESA's EnVision mission is critical for high-resolution surface mapping and geophysical studies of Venus. This work presents an innovative approach to orbit determination by combining radio tracking data with altimetric crossover measurements for trajectory estimation, while accounting for atmospheric drag perturbations. Venus's dense atmosphere introduces significant drag forces, especially at low altitudes, which must be carefully modeled to ensure precise orbit prediction. Synthetic datasets are produced by estimating atmospheric density from the Venus Climate Database, providing a detailed representation of atmospheric conditions. During the orbit determination phase, corrections to the spacecraft state vector are applied using the Venus-GRAM atmospheric model to account for density time variations. A thorough combination of radio and altimetric data significantly improves the orbit determination accuracy, which is a fundamental requirement for EnVision. An accurate reconstruction of the spacecraft state will enable a precise georeferencing of the measurements that are key to enhancing our understanding of Venus's geophysical properties and atmospheric dynamics.