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By Stephen Luntz

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Lunar Gravity Map Created
The creation of a detailed map of lunar gravity has revealed the internal workings of our nearest neighbour. “Our new lunar gravity map now shows, for the first time, how the pull of gravity changes from location to location over the rugged surface of the Moon,” says Dr Christian Hirt of Curtin University.

Space probes, particularly the 2007 Japanese SELENE mission, have provided large-scale maps of anomalies in lunar gravity. However, the height at which these missions have flown past prevent them from detecting smaller variations, such as those caused by mountains or craters.

“Recently the United States Lunar Reconnaissance Orbiter has provided a useful data source on lunar topography, containing rich information on expected gravity field signatures such as of small craters,” Hirt notes.

Hirt and Prof Will Featherstone combined information from these maps with far more detailed topographic data to estimate the gravity on a finer scale. The same technique has been verified on Earth, with comparison against local data.

Apollo 17 astronauts took detailed gravity measurements at around a dozen locations, but the spread represents a tiny portion of the Moon’s surface. Consequently Hirt acknowledges that the map assumes that the density of the surface materials is consistent over small scales.

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