Nasa's UARS satellite fell far from major landmass

Orbital tracking experts have now established that the defunct satellite entered the atmosphere over the Pacific Ocean at 14.1 degrees South latitude and 170.2 degrees West longitude, BBC News said.

Any debris that survived Saturday's fiery descent would have plunged into open water, the US space agency says.

The exact time the six-tonne craft engaged the atmosphere is now given as 0401 GMT.

The Upper Atmosphere Research Satellite (UARS) was the largest American space agency research platform to return uncontrolled from orbit in about 30 years.

Its fall from the sky generated huge interest worldwide at the weekend, with the possibility that its destruction would produce a spectacular fireball in the sky for anyone close enough to see it.

The return was monitored by the Joint Space Operations Center (JSPOC) at Vandenberg Air Force Base in California.

On Saturday, JSPOC's best estimate for the timing of the re-entry was 0416 GMT. Post-fall analysis has now brought that forward by 15 minutes, meaning the event occurred much further from the west coast of North America than was originally thought.

Modelling work had indicated perhaps 500kg of mangled metal could have survived to the surface, spread over a path some 800km long. If the latest analysis is correct, it seems certain all of that debris would have gone into the ocean.

"We have a high accuracy assessment based on a large number of data points, and we're very, very confident in our latest assessment," said Nick Johnson, Nasa's chief scientist for orbital debris at the Johnson Space Center in Houston. "Because the re-entry of the UARS satellite took place over the mid-Pacific Ocean, it's unlikely that anyone actually observed the re-entry."

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