GOCE satellite probing how pull of gravity varies across Earth

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London, December 25 (ANI): Reports indicate that Europe's GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) satellite is returning remarkable new data on the way the pull of gravity varies across Earth.

GOCE was launched by the European Space Agency (ESA) in March from the Plesetsk Cosmodrome in north-west Russia.

The information relayed by GOCE is expected to bring new insights into how the oceans move, and to frame a universal system to measure height anywhere on the planet.

According to a report by BBC News, the first maps built from GOCE observations were presented at the American Geophysical Union's (AGU) recent Fall Meeting, the world's largest annual gathering of Earth scientists.

Although they represent just 47 days of operation following the start of the satellite's science campaign on 30 September, the maps prove that GOCE is attaining an exceptional level of performance.

The 'standard' acceleration due to gravity at the Earth's surface s 9.8m per second squared

In reality, the figure varies from 9.78 (minimum) at the equator to 9.83 (maximum) at the poles.

"There is a tremendous amount of geophysics in these plots," explained Rune Floberghagen, ESA's GOCE mission manager.

"You see where there are big variations, for example in the mountain range of the Andes, or the Mariana Trench, or the Indonesian Arc, or the Himalayas. In fact, on most of the continents, you see a lot of variation," he told BBC News.

The maps reproduced by GOCE illustrate "gravity gradients".

The red colours on the map indicate a positive variation in gravity moving from one place to another, that is, places where Earth's tug becomes greater.

The blue colours indicate a negative variation in gravity - places where Earth's tug is a little less.

The Earth's interior layers are also not composed of perfect shells of homogenous rock - some regions are thicker or denser.

Such factors will cause g to deviate from place to place by very small but significant amounts.

The GOCE maps these differences with a state-of-the-art gradiometer produced by the French Onera company.

The instrument is sensitive to accelerations of about one-tenth of a millionth of a millionth of g.

The gradiometer measures these accelerations across all three axes of the spacecraft to obtain a multi-dimensional view of the Earth's gravity field.

"These are by far the smallest accelerations ever measured from orbit," said Dr Floberghagen. (ANI)

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