Geodesy — the study of a planet’s shape, orientation, and gravity field — is one of the most powerful methods for investigating the formation, evolution, structure, and active processes of Solar System bodies. Geodetic measurements from robotic missions to distant worlds have revealed oceans of liquid water within icy moons, probed the atmospheric dynamics of gas giants, and characterized the deep structure of terrestrial worlds. The power of geodesy is best demonstrated at the Earth and Moon, where spacecraft missions have transformed geodesy from a purely geophysical tool into one that unlocks advances in geology, climate change, hydrology, geochemistry, and more.
While geodesy in the Earth-Moon system has flourished, geodesy of other worlds has lagged behind. Closing this gap would revolutionize planetary science. New geodetic data could be used to locate hidden water resources on Mars, test how mantle dynamics operate in the absence of plate tectonics on Venus, explore the habitability of oceans on Europa and Enceladus, and address many other high-priority questions in planetary science.
report will provide a roadmap for the development of NASA planetary geodesy missions.
Check out our Enceladus geophysics white paper to the decadal survey here!
The picture above shows the gravity anomaly over the largest impact craters on Ceres. I study the formation and evolution of these impact craters, with the goal of providing a constraint on the thermal evolution and liquid water survivability within Ceres.
MAPPING MERCURY'S LITHOSPHERE
Mercury's tectonics is dominated by contractional features pointing at an earlier epoch of global contraction. I am leading a DDAP grant project to map the lithospheric thickness of Mercury using the MESSENGER spacecraft data. First, the lithospheric thickness will be estimated by measuring the flexural profiles of contractional features. Second, the lithospheric thickness will be mapped by modeling the localized gravity-topography admittance. Mapping lithospheric thickness with two methods and comparing the results to each other and other remote sensing datasets will constrain the thermal evolution and the history of lithospheric loading.
TIDAL TOMOGRAPHY OF VENUS ATMOSPHERE
Venus' massive atmosphere creates variations in Venus' gravity field that are just a factor of several below the sensitivity of the Magellan spacecraft data. Future missions to Venus will likely become sensitive to Venus' atmospheric gravity. In addition, the slow retrograde rotation of Venus has long been hypothesized to be due to a balance of the torques on the solid body tidal bulge and thermal atmospheric tidal bulge. The total torque acting on Venus can be estimated from the gravity measurements.