The aim of this paper is to propose a Mars Quantum Gravity Mission (MaQuIs). The mission is targeted at improving the data on the gravitational field of Mars, enabling studies on planetary dynamics, seasonal changes, and subsurface water reservoirs. MaQuIs follows well known mission scenarios, currently deployed for Earth, and includes state-of-the-art quantum technologies to enhance the gained scientific signal.

Mars hosts the largest volcano in our solar system, Mons Olympus. Up until now, flexural isostasy has commonly been used to understand the relationship between observed topography, crustal structure, and gravity. NASA’s InSight mission has brought new information about the Martian lithosphere, which warrants a re-analysis of the support of the large volcanic complex. After conducting spectral analysis on the topographic and gravity results from the flexural models, the gravitational signal of Martian topography with thin shell compensation fits well with the observed free-air anomaly for degrees, n≥2. The Martian lithosphere can be modelled by a thin shell model using the following parameters: crustal thickness of 60 ±10 km, crustal density of 3050 ±50 kg/m3, mantle density of 3550 ±100 kg/m3, and the best-fit elastic thickness (Te) is found to be 80 ±5 km. The remaining short scale gravity residuals give insight in Martian crustal density distributions. There appear to be buried mass anomalies in the subsurface of the northern polar plains, suggesting an older history of the northern hemisphere of Mars. A mismatch between modeled and observed gravity field for the long-wavelengths (between n=2-6 degrees) exists. The location of the residual anomaly correlates with the Tharsis Rise. which suggests active large-scale dynamic support of the volcanic region. A substantial negative mass anomaly in the mantle underneath the Tharsis Region can explain the gravity residual. Could mantle convection is still be active in Mars, explaining the relatively young geologic surface volcanism on Mars.

Venus is a terrestrial planet with dimensions similar to the Earth, but a vastly differentgeodynamic evolution, with recent studies debating the occurrence and extent of tectonic-like processes happening on the planet. The precious direct data that we have for Venusis very little, and there are only few numerical modeling studies concerning lithospheric-scale processes. However, the use of numerical models has proven crucial for our under-standing of large-scale geodynamic processes of the Earth. Therefore, here we adapt 2Dthermo-mechanical numerical models of rifting on Earth to Venus to study how the ob-served rifting structures on the Venusian surface could have been formed. More specif-ically, we aim to investigate how rifting evolves under the Venusian surface conditionsand the proposed lithospheric structure. Our results show that a strong crustal rheol-ogy such as diabase is needed to localize strain and to develop a rift under the high sur-face temperature and pressure of Venus. The evolution of the rift formation is predom-inantly controlled by the crustal thickness, with a 25 km-thick diabase crust required toproduce mantle upwelling and melting. The surface topography produced by our mod-els fits well with the topography profiles of the Ganis and Devana Chasmata for differ-ent crustal thicknesses. We therefore speculate that the difference in these rift featureson Venus could be due to different crustal thicknesses. Based on the estimated heat fluxof Venus, our models indicate that a crust with a global average lower than 35 km is themost likely crustal thickness on Venus.