Advancing Inter-Satellite Radio Occultation with MaCro on the M-MATISSE Mission

Radio occultation (RO) techniques provide valuable remote-sensing insights into planetary ionospheres and atmospheres by measuring the bending of radio signals as they traverse atmospheric layers. Mutual radio occultations between the Trace Gas Orbiter (TGO) and Mars Express (MEX) demonstrated the feasibility of this approach but were limited by hardware not designed for radio science occultation measurements—most notably, the absence of ultra-stable oscillators, single-frequency operation, and restricted timing precision.The Mars Magnetosphere ATmosphere Ionosphere and Space-weather SciencE (M-MATISSE) mission—currently in its Phase A study by the European Space Agency (ESA)—is a Medium-class (M7) candidate that will overcome these constraints through the dedicated MaCro (Mars Crosslink Radio Occultation) instrument: a dual-frequency, precision-timed, ultra-stable radio system purpose-built for inter-satellite occultations. MaCro’s design enables high-accuracy profiling of the Martian ionosphere and atmosphere across diverse geometries and solar conditions.This study systematically investigates how the known limitations of TGO–MEX influenced the retrieved electron density profiles and explores how modern machine-learning techniques—for example regression-based drift correction—can enhance the data-processing pipeline. The outcomes of this work will support the development of MaCro’s data processing chain and contribute to the improvement of its performance.