WASHINGTON — The United States will try to shoot down a disabled spy satellite that's expected to re-enter the Earth's atmosphere within the next two weeks, the Pentagon said Thursday, marking the first time the military will use its missile defense program to attempt to bring down a satellite.
Military officials said President Bush ordered the Navy to try to bring down the satellite because the chemicals aboard could endanger populated areas. Of particular concern are the 1,000 pounds of hydrazine, an ammonia-like component of rocket fuel that's highly toxic if inhaled or swallowed.
Congressional leaders who were briefed on the plan generally approved, though the idea of blasting a satellite from orbit is controversial. Last year, U.S. officials were critical when China destroyed a satellite with a missile.
"I am satisfied that the destruction of the malfunctioning satellite is the best option available to protect public safety," said Rep. Ike Skelton, D-Mo., the chairman of the House Armed Services Committee. "However, it should be understood by all, at home and abroad, that this is an exceptional circumstance and should not be perceived as the standard U.S. policy for dealing with errant satellites."
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Marine Gen. James Cartwright, the vice chairman of the Joint Chiefs of Staff, said a Navy cruiser would try to hit the satellite with a Standard Missile 3, which is designed to bring down ballistic missiles.
The decision about when to launch the missile will depend on where Pentagon planners think the satellite will land if it's hit.
"We'll take one shot and assess," Cartwright said.
Deputy National Security Adviser James Jeffrey said that the United States is notifying scores of countries of its plans.
Cartwright refused to say who built the satellite or its purpose, but he said that military controllers lost contact with it within hours of its launch in December 2006.
Various aviation publications said that Lockheed Martin built the satellite at a cost of several hundred million dollars for the National Reconnaissance Office, the government agency that manages many of the nation's spy satellites. Lockheed Martin spokesman Chip Manor declined to provide additional details.
Cartwright said the military decided to move against the satellite to lessen the risk that the hydrazine would be scattered in a populated area. He said scientists estimate that the chemical could be scattered over an area the size of two football fields if the satellite breaks apart over land.
Hydrazine can damage vital organs and the central nervous system if swallowed or inhaled.
Experts said that the risk would vary widely, however, depending on wind conditions and a person's distance from where the satellite lands.
Cartwright said military planners hope to lower the risk of exposure by hitting the satellite before it begins its re-entry into the atmosphere. That will allow the military to influence whether the satellite crashes onto land or into water.
"Once it hits the atmosphere, it tumbles, it breaks apart (and will become) next to impossible to engage," Cartwright said.
NASA administrator Michael Griffin said the plans add little to the risk from the satellite's descent. "There is almost nothing we can do here that will make it worse," Griffin said.
Concerns over the satellite's fate have been rising since the military announced last month that it was falling to Earth.
Griffin tried to distinguish the U.S. plans from China's downing last year of one of its defunct weather satellites, noting that the Chinese action was a test of an anti-satellite program, while the U.S. plans are intended to ensure human safety.
He said that the satellite that the Chinese destroyed was 528 miles from the Earth's surface, while the U.S. satellite will be much closer to the ground when the Navy fires at it.
He said debris from the U.S. satellite should fall into the atmosphere and burn up within days, while the Chinese satellite's debris will remain a threat in space for years.
"It's an enormous difference," Griffin said.
Griffin said NASA's current space shuttle mission wouldn't be disturbed by the military's plan.