section_path: Physical characteristics/Gravitational field
section_name: Gravitational field
paragraph_text: Gravitational field
  
  On average the Moon's surface gravity is 1.62 m/s (0.1654 g; 5.318 ft/s), about half of the surface gravity of Mars and about a sixth of Earth's.
  
  The Moon's gravitational field is not uniform. The details of the gravitational field have been measured through tracking the Doppler shift of radio signals emitted by orbiting spacecraft. The main lunar gravity features are mascons, large positive gravitational anomalies associated with some of the giant impact basins, partly caused by the dense mare basaltic lava flows that fill those basins. The anomalies greatly influence the orbit of spacecraft about the Moon. There are some puzzles: lava flows by themselves cannot explain all of the gravitational signature, and some mascons exist that are not linked to mare volcanism.