Six-tonne satellite to fall from orbit

The $750 million Upper Atmosphere Research Satellite (UARS), launched to study climate change, will fall in a few weeks, The Telegraph reported.

Though NASA said the risk to public safety from the satellite was "extremely small", officials are concerned about the risk to billions of people when the satellite starts falling uncontrolled out of orbit.

A major chunk of the satellite will burn up after entering Earth's atmosphere, but more than half a tonne of metal will survive, NASA said. While NASA did not know the exact areas it will fall, the projected danger zone has been narrowed to areas between 57 degrees north and 57 degrees south of the Equator.

These areas cover six continents and billions of people and three oceans. Gene Stansbery, NASA's orbital debris chief said: "Things have been re-entering ever since the dawn of the space age. To date nobody has been injured by anything that's re-entered. That doesn't mean we're not concerned."

The satellite, launched by space shuttle Discovery in 1991, is 35 feet long, 15 feet in diameter, weighs 13,000 pounds, and carries 10 instruments. It was designed to operate for three years but six of its 10 instruments are still working. It ran out of fuel in 2005.