NASA Map of Mars Gravity

A new map of Mars' gravity is the most detailed to date, providing a revealing glimpse into the planet's hidden interior. The map was derived using Doppler and range tracking data collected by NASA's Deep Space Network from three NASA spacecraft in orbit around Mars: Mars Global Surveyor, Mars Odyssey, and the Mars Reconnaissance Orbiter. via NASA http://www.nasa.gov/image-feature/map-of-mars-gravity