ESA boffins meet to plot gravity field plotting

Mission slated for 2007 launch

Over 150 scientists met in Italy this week for the third international GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) workshop.

The ESA mission is scheduled to launch next year and is the first in a series of Living Planet missions planned by the European Space Agency (ESA). It will spend 20 months gathering data on the Earth's gravitational field.

GOCE is unusual because it will fly in such a low orbit, just 250km above our heads, its design has had to account for the effects of the Earth's atmosphere. As a consequence, the satellite is a long, but narrow, octagonal tube. It also has an ion engine to counteract the atmospheric drag.

ESA head of Ocean Ice Unit Dr Mark Drinkwater described the satellite as the "Ferrari of gravity missions".

The mission's gradiometer is comprised of three pairs of accelerometers oriented along, across, and radially (pointing from the centre of the Earth outwards) to the flight track of the satellite. This means the researchers can record gradients in the Earth's gravity field, Drinkwater explained.

This data will allow scientists to model the geoid, the hypothetical surface of the Earth, reflecting the variations of the gravity field. ESA says this data will give scientists insight into the internal dynamics of our planet, as well as events on the surface.

Dr Reiner Rummel, Tech University of Munich explains how our gravity field affects the oceans and, in turn, our climate.

"The oceans deviate slightly from the level, and these deviations are what cause the oceans to move, to circulate. " he said. "This circulation is very important for understanding our climate, because it explains how heat is transported from the equator, how mass is transported, how polluted materials are transported,"

GOCE will allow the first direct measurement of how oceans move and will also help scientists explain sea-level changes, he said.

Dr Drinkwater says GOCE will give details of how the gravitational field is affected by plate tectonics, which in turn should help improve models of how the Earth's crust moves and changes. He noted that this could eventually improve predictions of earthquakes and volcanic activity. ®

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