Gravimetry

Gravimetry is the measurement of the Earth’s gravity field—specifically the acceleration of gravity (g) at or near the Earth’s surface. Changes or anomalies in gravity are linked to variations in mass distribution (e.g. density contrasts in subsurface rock, water movement, or ice mass changes). It includes terrestrial (ground, marine, airborne) techniques and satellite gravimetry, which infers gravity from orbital perturbations.

More Info: https://geodesy.science/item/satellite-gravimetry/