NASA Podcasts

NASA Mission Update: GRACE
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Everything, from the motion of the ocean tides, to the expansion of the universe, is controlled by gravity.

Here on Earth, gravity's pull varies from place to place, depending upon an area's mass. Making precise measurements of these variations is the mission of the Gravity Recovery and Climate Experiment, or GRACE.

John LaBrecque, GRACE Program Scientist: "It measure the changes in the Earth's pull of gravity to about one part in one billion. It's extremely sensitive."

Launched on March 17, 2002, the GRACE mission notes when the distance between its orbiting twin satellites changes as they pass over variations in the Earth’s gravitational mass. A map of these gravity-field variations, accurate to within a centimeter, equips scientists with a new, more accurate baseline against which they can compare any subsequent change in Earth's mass.

John LaBrecque, GRACE Program Scientist: "From the ice caps to the oceans to the lands and river valleys; the motion of mass during earthquakes. GRACE has really helped us to build a foundation for variability of our Earth's climate system."

By quantifying any changes in mass around the Earth, GRACE is providing precise, up-to-date data that are helping scientists predict and better understand the future of our environment.

John LaBrecque, GRACE Program Scientist: "One of the big uncertainties prior to GRACE was, 'Are the ice caps melting? If so, how fast? Are they increasing in size and, if so, how fast? The Alaskan ice fields, the Greenland ice caps. Antarctica." GRACE has provided us with some of the first global measurements of these changes in mass."

To learn more about the GRACE mission, visit

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