Gravity Field Investigation Package
The Gravity Field Investigation will study the Doppler shift in the radio communications signal to determine the gravitational field.
These observations will be used to understand the subsurface structure of Mars on the scale of several hundred kilometers, and the rigidity of the planet as a whole.
The gravity field also provides information on the density of the atmosphere at the spacecraft altitude and on the seasonal changes in the location of carbon dioxide deposited at the surface. The team leader is Maria Zuber from the Massachusetts Institute of Technology/ Goddard Space Flight Center.