Maria Zuber on project to map moon’s gravity

Maria Zuber: If you want to understand a planet, understanding the inside is just as important as understanding the outside.

That was Maria Zuber, a geophysicist at MIT who will lead a science mission to Earth’s moon, called GRAIL, set for launch in 2011.

Maria Zuber: GRAIL measures gravity. The name stands for Gravity Recovery and Interior Laboratory, and gravity tells us how mass is distributed in a planet.

The denser the rock, the stronger its gravity field. GRAIL consists of two satellites that’ll orbit the moon for about 90 days, like a pair of mini-moons of the moon. As one satellite flies over lunar rock of different densities, gravity slightly pulls and releases it. The other satellite follows along and tracks the changes to the first, and an x-ray picture of the moon emerges.

Maria Zuber: We’re actually going to produce a gravity map of the moon that’s going to have a spatial resolution better than the global gravity model for Earth.

That’s because the GRAIL satellites can orbit the moon much lower than terrestrial satellites. Zuber said that GRAIL might find out whether the inside of the moon is like Earth, with a core, a mantle, and crust.

Maria Zuber: On the moon, we have a crust, we don’t know very well how thick it is, because we don’t have any gravity observations on the far side.

What’s more, understanding lunar gravity will help future missions land safely on the moon. Our thanks to NASA, in celebration of the International Polar Year.

Our thanks to:
Maria Zuber
Massachusetts Institute of Technology
Cambridge, MA

March 28, 2008

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