Archive - Lunar Gravity Field from GRAIL

December 23, 2018



Each Sunday we present a notable item from our archives. This EPOD was originally published December 19, 2012.

: GRAIL’s Gravity Map of the Moon (NASA/ARC/MIT)
Summary Authors: NASA/JPL-Caltech/MIT/GSFC

These two images show variations in the Moon’s gravity field as observed by NASA's Gravity Recovery and Interior Laboratory (GRAIL) during its primary mapping mission from March to May 2012. The top image shows a portion of the far side of the Moon (right) and a portion of the nearside (left). At bottom is a Mercator projection of the complete lunar surface – the far side is at center and the nearside at far left as well as far right. Precise microwave measurements between the washing-machine-sized spacecraft, named Ebb and Flow, were used to map the lunar gravity with high precision and high spatial resolution. Measurements are three to five orders of magnitude improved over previous data. Here, red corresponds to mass excesses (mountains, for example) and blue corresponds to mass deficiencies (lowlands). The spherical red splotch on the top photo, just left of center, is seen at left center on the Mercator view, and the bull’s-eye-like object at upper right of the top photo is at upper left-center on the bottom image (a little above and to the right of the red splotch). Note that there’s more small-scale detail on the far side of the Moon compared to the near side since the far side has considerably more small impact craters. Data from Ebb and Flow will help to provide a better understanding of how Earth and other terrestrial planets in the solar system formed and evolved.