The Pentagon plans to shoot down a disabled U.S. spy satellite before it enters the atmosphere to prevent a potentially deadly leak of toxic gas from the vehicle's fuel tank, officials said on Thursday.
President George W. Bush decided to have the Navy shoot the 5,000-pound (2,270 kg) minivan-sized satellite with a modified tactical missile, after security advisers suggested its re-entry could lead to a loss of life.
U.S. officials said they were not trying to protect classified information on the satellite or to demonstrate their capabilities to China, which downed one of its own satellites with a missile last year, drawing criticism from Washington.
Some experts disagreed and questioned the risks associated with shooting down the satellite.
Two defence officials also cited disagreement within the administration over the action and said the decision appeared to have been strongly influenced by the White House.
The Pentagon hopes to strike the satellite just before it reaches the atmosphere and drive it into ocean waters. Officials would not estimate the likelihood of success, only calling it high.
Thousands of space objects fall to Earth each year, but they generally scatter over a huge area and there have never been any reported injuries.
What makes this different is the likelihood the satellite could release much of the more than 1,000 pounds (454 kg) of hydrazine fuel as a toxic gas, according to James Jeffrey, deputy national security adviser.
He said the satellite was unlikely to hit a populated area and described the danger from toxic gas as limited. But Jeffrey added, "There was enough of a risk for the president to be quite concerned about human life."
There is also no downside to trying, NASA Administrator Michael Griffin said. If the missile misses, there is no change. If it just grazes the satellite, the satellite will start to re-enter the atmosphere, as it will soon anyway.
"There is almost nothing we can do here that makes it worse," Griffin said.
SIGNAL TO CHINA?
