NASA's GRAIL Mission Maps Out The Moon's Uneven Gravity

The moon may look round to us from down here on Earth, but the surface of our lunar companion is riddled with craters and varying densities which give the moon uneven gravitational pulls. For the first time, NASA scientists have properly mapped out the cause of this phenomenon. 

NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission used a spacecraft to map the structure and composition of the moon. When GRAIL's data was combined with data concerning asteroids and impact craters, GRAIL scientists were able to identify dense regions known as massive concentrations, or mascons, caused by lava filling craters or the iron mantle swelling up to the crust.

"GRAIL data confirm that lunar mascons were generated when large asteroids or comets impacted the ancient moon, when its interior was much hotter than it is now," said Jay Melosh, a member of the GRAIL team and lead author of the paper published May 30 in the journal Science. "We believe the data from GRAIL show how the moon's light crust and dense mantle combined with the shock of a large impact to create the distinctive pattern of density anomalies that we recognize as mascons." 

Mascons are not necessarily new to scientists. They were identified back in 1968 by a NASA Jet Propulsion Laboratory team, but it isn't until now that the extent of mascons underneath the moon's surface has been mapped properly.

"Knowing about mascons means we finally are beginning to understand the geologic consequences of large impacts," Melosh said. "Our planet suffered similar impacts in its distant past, and understanding mascons may teach us more about the ancient Earth, perhaps about how plate tectonics got started and what created the first ore deposits." 

By better understanding the mass makeup of the moon, and thus its gravity, NASA hopes the findings will allow for better lunar navigation.

You can read the full NASA press release here.