Europe’s GOCE Satellite Takes Gravity’s Final Measure as It Breaks up Over Ocean

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PARIS — Europe’s GOCE gravity-measurement satellite, which broke up in the atmosphere as scheduled early Nov. 11, continued to generate useful data as it was pulled into Earth’s atmosphere and the temperature of its computer and battery rose to above 80 degrees Celsius, the European Space Agency (ESA) said Nov. 11.

The 20-nation ESA estimated that about 25 percent of GOCE’s total mass on re-entry, or about 250 kilograms, likely survived to land somewhere in the southern Atlantic Ocean between South America and Antarctica based on data provided by the U.S. Strategic Command.

Launched in March 2009, the Gravity field and steady-state Ocean Circulation Explorer spacecraft, shaped like an arrowhead and powered by a xenon-electric system including 41 kilograms of xenon fuel, far outlived its expected lifespan.

GOCE’s fuel supply was depleted Oct. 21, but it kept sending data as late as Nov. 10 to the Troll ground station in Antarctica, when its altitude was no more than 120 kilometers. Friction from the atmosphere by then had increased the temperature of GOCE’s computer to 80 degrees and its battery to 84 degrees, ESA said.

The agency estimated that GOCE began to disintegrate at about 80 kilometers in altitude as it descended along a path taking it over Siberia, the western Pacific Ocean, the eastern Indian Ocean and Antarctica.

GOCE managers said gravity-field experts will be studying GOCE data for years, but it was the uncontrolled descent that produced more media attention in GOCE’s final weeks than the mission ever got during its productive life.

 

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