Gravity Gradients Frame Oceanus Procellarum

Topography of Earth's moon generated from data collected by the Lunar Orbiter Laser Altimeter, aboard NASA's Lunar Reconnaissance Orbiter, with the gravity anomalies bordering the Procellarum region superimposed in blue. The border structures are shown using gravity gradients calculated with data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission. These gravity anomalies are interpreted as ancient lava-flooded rift zones buried beneath the volcanic plains (or maria) on the nearside of the Moon.

Launched as GRAIL A and GRAIL B in September 2011, the probes, renamed Ebb and Flow, operated in a nearly circular orbit near the poles of the moon at an altitude of about 34 miles (55 kilometers) until their mission ended in December 2012. The distance between the twin probes changed slightly as they flew over areas of greater and lesser gravity caused by visible features, such as mountains and craters, and by masses hidden beneath the lunar surface.

The twin spacecraft flew in a nearly circular orbit until the end of the mission on December 17, 2012, when the probes intentionally were sent into the moon's surface. NASA later named the impact site in honor of late astronaut Sally K. Ride, who was America's first woman in space and a member of the GRAIL mission team.

GRAIL's prime and extended science missions generated the highest-resolution gravity field map of any celestial body. The map will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

Image credit: NASA/Colorado School of Mines/MIT/GSFC/Scientific Visualization Studio

Note: For more information, see PIA18821: On the West Coast of the Ocean of Storms (Artist's Concept) and NASA Mission Points to Origin of 'Ocean of Storms' on Earth's Moon.

North Polar Gravitational Map of the Moon

This is a polar stereographic map of gravity of the north polar region of the moon from the Gravity Recovery and Interior Laboratory (GRAIL) mission. The map displays the region from latitude 60 north to the pole. The data was collected during GRAIL's extended mission which took place from August 30 to December 17, 2012. In the image, red corresponds to mass excesses and blue and purple to mass deficiencies.

Map credit: NASA/MIT/JPL/GSFC/GRAIL

Note: For more information, see NASA's GRAIL Mission Solves Mystery of Moon's Surface Gravity.

Lunar Gravity Map by Grail

This image shows the variations in the lunar gravity field as measured by NASA's Gravity Recovery and Interior Laboratory (GRAIL) during the primary mapping mission from March to May 2012. Very precise microwave measurements between two spacecraft, named Ebb and Flow, were used to map gravity with high precision and high spatial resolution. The field shown resolves blocks on the surface of about 12 miles (20 kilometers) and measurements are three to five orders of magnitude improved over previous data. Red corresponds to mass excesses and blue corresponds to mass deficiencies. The map shows more small-scale detail on the far side of the moon compared to the nearside because the far side has many more small craters. › See video

Image credit: NASA/JPL-Caltech/MIT/GSFC

NASA's GRAIL Spacecraft in Science Collection Phase

An artist's depiction of the twin spacecraft that comprise NASA's Gravity Recovery And Interior Laboratory (GRAIL) mission. During the GRAIL mission's science phase, spacecraft (Ebb and Flow) transmit radio signals precisely defining the distance between them as they orbit the Moon in formation. As the two fly over areas of greater and lesser gravity caused by both visible features, such as mountains and craters, and masses hidden beneath the lunar surface, the distance between the two spacecraft will change slightly. Mission scientists use this information to create a high-resolution map of the Moon's gravitational field. The data will allow scientists to understand what goes on below the lunar surface. This information will increase knowledge of how Earth and its rocky neighbors in the inner solar system developed into the diverse worlds we see today.

Illustration credit: NASA/JPL-Caltech/MIT

Note: See also PIA13965: GRAIL Spacecraft Over the Moon.