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Wednesday, December 05, 2012

New Moon Graviety Field Map Released


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.  
 
CREDIT: NASA/JPL-Caltech/MIT/GSFC
The short movie above shows the variations in the lunar gravity field as measured by 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 times 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.

GRAIL Principal Investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge notes that the moon's gravity field preserves the record of impact bombardment that characterized all terrestrial planetary bodies and reveals evidence for fracturing of the interior extending to the deep crust and possibly the mantle. This impact record is preserved, and now precisely measured, on the moon. 
 
CREDIT: NASA/JPL-Caltech/MIT/GSFC
The map was created by the spacecraft transmitting radio signals to define precisely the distance between them as they orbit the moon in formation. As they fly over areas of greater and lesser gravity caused by visible features, such as mountains and craters, and masses hidden beneath the lunar surface, the distance between the two spacecraft will change slightly.
 
While results from the primary science mission are just beginning to be released, the collection of gravity science by the lunar twins continues. GRAIL's extended mission science phase began Aug. 30 and will conclude Dec. 17, 2012. As the end of mission nears, the spacecraft will operate at lower orbital altitudes above the moon.
 

Press Conference with the NASA-JPL-MIT-Goddard ard Team. 

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