Jun 29, 2010

Goce satellite data allows boffins to map Earth's gravitational pull

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Data gathered by the European Space Agency’s Goce satellite has allowed scientists to draw a map that traces the pull of gravity across the globe.

Known as a geoid, the map defines where the level surface is on the Earth; it helps us understand which way is “up” and which way is “down”.

The new map was presented at Bergen, Norway, at a special Earth observation (EO) symposium dedicated to the data being acquired by Goce and other European Space Agency (Esa) missions.

Launched last year, the Gravity Field and Steady-State Ocean Circulation Explorer (Goce) flies pole to pole at an altitude of 254.9km – the lowest orbit of any research satellite in operation today.

The spacecraft carries three pairs of precision-built platinum blocks inside its gradiometer instrument that sense accelerations which are as small as 1 part in 10,000,000,000,000 of the gravity experienced on Earth.

This allows it to map almost undetectable differences in the pull exerted by the mass of the planet from one place to another.

Two months of observations have now been translated into what scientists have dubbed the geoid.

“I think everyone knows what a level is in relation to construction work, and a geoid is nothing but a level that extends over the entire Earth,” The BBC quoted Professor Reiner Rummel, the chairman of the Goce scientific consortium, as saying.

Rummel added: “So with the geoid, I can take two arbitrary points on the globe and decide which one is ‘up’ and which one is ‘down’.”

Dr Rune Floberghagen, Esa’s Goce mission manager, said: “The Goce data is showing up new information in the Himalayas, central Africa, and the Andes, and in Antarctica.

“This is, in one sense, not so surprising. These are places that are fairly inaccessible. It is not easy to measure high frequency variations in the gravity field in Antarctica with an aeroplane because there are so few airfields from which to operate.” (ANI)

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