Gravity Map of the Moon by GRAIL

This is the most accurate gravity map of the Moon, as measured by NASA’s GRAIL mission. Image credit: NASA/ARC/MIT

Image credit: NASA/ARC/MIT

The viewing perspective, known as a Mercator projection, shows the far side of the moon in the center and the nearside (as viewed from Earth) at either side.

Twin NASA probes orbiting Earth’s moon have generated the highest resolution gravity field map of any celestial body.

The new map, created by the Gravity Recovery and Interior Laboratory (GRAIL) mission, is allowing scientists to learn about the moon’s internal structure and composition in unprecedented detail. Data from the two washing machine-sized spacecraft also will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

The gravity field map reveals an abundance of features never before seen in detail, such as tectonic structures, volcanic landforms, basin rings, crater central peaks and numerous simple, bowl-shaped craters. Data also show the moon’s gravity field is unlike that of any terrestrial planet in our solar system.

These are the first scientific results from the prime phase of the mission, and they are published in three papers in the journal Science.

“What this map tells us is that more than any other celestial body we know of, the moon wears its gravity field on its sleeve,” said GRAIL Principal Investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. “When we see a notable change in the gravity field, we can sync up this change with surface topography features such as craters, rilles or mountains.”

Image credit: NASA/JPL-Caltech/ IPGP

This image depicting the porosity of the lunar highland crust was derived using bulk density data from NASA’s GRAIL mission and independent grain density measurements from NASA’s Apollo moon mission samples as well as orbital remote-sensing data. Red corresponds to higher than average porosities and blue corresponds to lower than average porosities. White denotes regions that contain mare basalts (thin lines) and that were not analyzed.

The 12 percent average porosity of the highland crust is a consequence of fractures generated by billions of years of impact cratering. The crustal porosities in the interiors of many impact basins are lower than their surroundings, a result of high temperatures experienced at the time of crater formation. In contrast, the porosities immediately exterior to many impact basins are higher than average as a result of fracturing by impact-generated shock waves and the deposition of impact ejecta.