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Missile Used To Bring Down Orbiting Satellite

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By ROBERT BURNS, The Associated Press

Published: February 21, 2008

WASHINGTON - A missile launched from a Navy ship struck a dying U.S. spy satellite passing 130 miles over the Pacific on Wednesday, the Pentagon said.

It probably succeeded in its main goal of destroying a tank aboard the satellite that carried a toxic fuel that U.S. officials said could pose a hazard to humans if it landed in a populated area, a military official said.

But, "Confirmation that the fuel tank has been fragmented should be available within 24 hours," the Pentagon said in a written statement.

The USS Lake Erie, armed with an SM-3 missile designed to knock down incoming missiles - not orbiting satellites - launched the attack at 10:26 p.m. EST, according to the Pentagon. It hit the satellite as the spacecraft traveled at more than 17,000 mph.

Because the satellite was orbiting at a relatively low altitude at the time it was hit by the missile, debris will begin to re-enter the Earth's atmosphere immediately, the Pentagon statement said.

"Nearly all of the debris will burn up on re-entry within 24-48 hours and the remaining debris should re-enter within 40 days," it said.

The use of the Navy missile amounted to an unprecedented use of components of the Pentagon's missile defense system, designed to shoot down hostile ballistic missiles in flight - not kill satellites.

The operation was so extraordinary, with such intense international publicity and political ramifications, that Defense Secretary Robert Gates - not a military commander - was to make the final decision to pull the trigger.

The Centers for Disease Control and Prevention sent out a health advisory starkly describing the risks posed by the rocket fuel, and the Federal Emergency Management Agency released a newly published, 18-page document detailing how emergency workers should handle the substance.

The "First Responder Guide for Space Object Re-Entry" was sent by e-mail to communities across the nation, and the administration also mobilized six of what it called "joint interagency task forces" under the codename "Burnt Frost" around the country to reach the site of any satellite debris impact. The steps were taken in coordination with the Defense Department.

But several scientists, including Massachusetts Institute of Technology research professor Geoffrey Forden, said they had estimated the risks of exposure to the satellite and its components, including the fuel, and found them to be exceedingly low.

Forden found a 3 percent chance that an individual somewhere in the world would be injured by the hydrazine if any fell to Earth. For a resident around Los Angeles, for example, the risk of being harmed is one in a billion, Forden said. The government estimates the risk of being struck by lightning at one in 700,000.

Forden and his colleagues concluded that the possibility of the toxic gas making it to land is very close to zero. "The amount of pressure on that tank will be enormous - about 50 times the gravitational force on Earth," he said. "We can't see how it would possibly make it through the atmosphere."

Harvard astrophysicist Jonathan McDowell separately concluded the chance that a piece of the satellite might strike someone directly is about one in a million. The chances the hydrazine will land within 100 yards of someone if the tank makes it through Earth's atmosphere, he said, are higher: about 2 in 100. But "if people just walk away from it, they won't be harmed at all," he said.

Both McDowell and Forden said that NASA and the Defense Department should release the data used by the government to conclude the health risks were so great that the satellite should be destroyed by a missile - at an estimated cost of more than $30 million - before it enters Earth's atmosphere and breaks apart.

Skeptics in the arms control community have speculated that the administration chose to undertake the shoot-down partly so it can test potential anti-satellite weapons and missile defense technology. Some have also speculated that Washington may want to send a message to China, which conducted an anti-satellite test last year, or to keep potentially valuable technology from falling into the wrong hands.

Pentagon officials have denied the claim and said they take the risks seriously, noting that a similar tank on the space shuttle Columbia fell unbroken to Earth during a 2003 disaster. Wednesday's CDC health advisory said, for example, that those who breathe hydrazine can suffer convulsions, tremors or seizures.

"There's only a small chance the hydrazine will land in a populated area or cause injury or death, but there's still a chance that it could," said Bryan Whitman, a Pentagon spokesman. "The United States has a chance to mitigate that risk or possibly eliminate it. We have this capability and can reduce the risk to human life on this planet, and that's why we're doing it."

Forden and others say it is unfair to compare the Columbia mishap with what might happen with the spy satellite.

While the Columbia broke apart at about 40 miles above Earth, this satellite is expected to break apart not long after it hits the atmosphere, at about 80 miles above Earth, giving it longer to burn up.

Information from The Washington Post was used in this report.

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