A European spacecraft that skims the upper reaches of the atmosphere has mapped Earth's gravity with unrivaled precision. The map below shows how the pull of gravity varies minutely over the surface of the Earth, from deep ocean trenches to majestic mountain ranges.
The measurements have allowed scientists to create a computer model called a 'geoid' that reveals what Earth would look like if its shape were altered to make gravity equal at every point on the surface.
Researchers unveiled the latest data from the European Space Agency's Gravity and Ocean Circulation Explorer, or Goce, at a workshop in Munich on Thursday.
Data from the five-meter-long spacecraft will be crucial for understanding sea level changes, shifts in ice flows and how ocean currents – which are driven by gravity – respond as the planet warms over the next few decades.
The spacecraft circles the Earth at an altitude of 150 miles (250km) and uses an ion rocket to prevent it losing height as it flies through wisps of atmosphere.
Described by project manager Andrea Allasio as "the Ferrari of space probes", GOCEmaps Earth's gravitational field by recording its exact position with GPS and detecting variations in the pull of gravity accurate to one part in ten million million.
Earth's gravity is subtly influenced by all manner of changes in the structure and topography of the Earth. The planet is not a perfect sphere, instead bulging around the equator, making gravity weaker there than at the poles. Gas fields, mineral deposits, aquifers and rock formations also affect the pull of gravity.
Information from GOCE is already being analyzed to get a deeper understanding of the geological processes that cause earthquakes. The recent quake that brought devastation to Japan was triggered by the sudden movement of tectonic plates beneath the ocean. These dramatic movements in rock leave signatures in gravity data that could provide fresh insights into how they occur.
The satellite was launched in March 2009 and has now collected more than two year's worth of gravity data. The probe has enough fuel to fly until the end of 2012, a doubling of its intended mission life.
"At its early conception, GOCE was more like science fiction. GOCE has now clearly demonstrated that it is a state-of-the-art mission," said Volker Liebig, director of Esa's Earth Observation Programs.
Posted By Zach Royer | 4:44 PM PST | March 31st, 2011
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