A missile launched from a Navy ship struck a dying U.S. spy satellite passing 130 miles over the Pacific Ocean yesterday, the Pentagon said.
A Defense Department official said an initial view of the missile strike on the spy satellite indicated that it probably hit the spacecraft's fuel tank, whose toxic contents were the main target of the missile launch, the Associated Press reported.
"Due to the relatively low altitude of the satellite at the time of the engagement, debris will begin to re-enter the Earth's atmosphere immediately," the Pentagon said in a news release last night. "Nearly all of the debris will burn up on re-entry within 24 to 48 hours, and the remaining debris should re-enter within 40 days."
The U.S. military has shot down missiles in flight before - 12 times while testing key parts of its $9 billion missile defense effort. It even destroyed an orbiting satellite in 1985.
But the Pentagon's plan to blast an errant spy satellite out of the heavens posed unique technological challenges. It could have been an embarrassment if its main mission failed - and an international liability even if it has succeeded, experts say.
The satellite, known as USA-193, was built by Lockheed Martin Corp. and failed shortly after launch in December 2006. In addition to its high-tech payload, it contains about 1,000 pounds of frozen hydrazine, a hazardous propellant stored in a metal tank.
The Pentagon said the tank and hydrazine would pose a hazard if they landed in a populated area, so officials planned to take out the satellite by blasting it with an Aegis missile launched from a Navy cruiser in the Pacific.
The missile was launched from the USS Lake Erie about 10:25 p.m. EST. The government had notified sailors and aviators to stay clear of parts of the Pacific beginning about 10:30 p.m. EST.
The guided missile was specifically part of the Aegis Ballistic Missile Defense System, which has hit 12 out of 14 targets during flight tests, according to a Defense Department spokesman.
"It's one of the Defense Department's more successful anti-missile systems," said Dr. Jonathan C. McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
Some experts have compared the task of hitting the satellite to hitting a bullet with a bullet about 150 miles above Earth.
The satellite, the size of a small bus, was speeding through space at 18,000 mph, about twice as fast as the test missiles previously targeted. "It's moving at roughly 300 miles a minute, and so you need to know where it's going to hit. And if you're off by just a minute on that, that's 300 miles off," said Ivan Oelrich, vice president for strategic security programs at the Federation of American Scientists.
Nor was the 40-pound missile equipped with explosives - it was to rely on its own kinetic energy to smash the 5,000-pound satellite to bits, experts say.
Had the Navy missed, it could have proved a highly visible failure for the Defense Department's $1 billion-a-year Aegis Ballistic Missile Defense System.
Then there are international politics. Some experts say the move is a U.S. attempt to counter actions by the Chinese last year. China blasted one of its own weather satellites on Jan. 11, 2007, prompting criticism that it had created thousands of new shards of hazardous space debris and escalated international tensions about conflicts in space.
The U.S. effort is not expected to create as much space debris because the point of impact is closer to Earth. But it might still spark international tensions, experts say. "It takes us further along that road of weapons in space and war in space," McDowell said.
Chinese and Russian officials recently proposed a ban on anti-satellite missile testing in space. The Bush administration has rejected the proposal as unverifiable.
"Yet again, we have a superpower testing what the world will perceive is a space weapon," said Phil Smith, assistant director of the Secure World Foundation, a nonprofit group organized to promote peace in space.
Others, too, are suspicious of the Pentagon's motives. "So far, in the entire history of the Space Age, no manmade object has badly injured anyone," said Michael Krepon, director of the Space Security Project at the Henry L. Stimson Center in Washington.
The Pentagon has never provided estimates on the risk attached to the demise of the satellite. But Krepon said other experts have put the risk that a single human being would be injured by the satellite at between 1 percent and 3.5 percent - not worth the "extreme measures" being undertaken.
Krepon offered two other explanations that he considers more plausible. The first is the protection of "state secrets" - a fear that key components of the satellite could fall into Russian or Chinese hands and divulge something about our spy technology.