Navy Missile Hits Satellite, Pentagon Says

Some scientists calculated that the tank of hydrazine could not possibly survive a descent through the atmosphere, and others said that even if it did, the chances of anyone being injured were extremely small. Some worried that the U.S. decision to adapt a rocket designed for missile defense to serve as an anti-satellite weapon would encourage other nations to experiment with their own anti-satellite technology.

In January 2007, China shot down an aged satellite orbiting about 600 miles above Earth and was roundly criticized by the United States and many other nations for doing so. That anti-satellite test created thousands of pieces of debris that will remain a potential hazard to orbiting spacecraft for decades.

Administration critics worried that debris from the U.S. intercept could harm other satellites as well, especially if the pieces are pushed far out into space by the force of the strike. But NASA Administrator Michael D. Griffin and Marine Gen. James E. Cartwright, vice chairman of the Joint Chiefs of Staff, said they expect half of the debris to fall to Earth quickly and the rest to remain in safe low orbit until it descends in the next few weeks.

Most information about the malfunctioning spy satellite is classified, but space and defense experts believe that it was launched from Vandenberg Air Force Base in California in December 2006 and that it malfunctioned soon after reaching low-Earth orbit. That spacecraft, called L-21 and commissioned by the government's National Reconnaissance Office, cost hundreds of millions of dollars and included the most advanced radar imaging technology, said defense analyst John Pike of GlobalSecurity.org.

He said there is "good reason" to believe that it was part of the National Reconnaissance Office's Future Imagery Architecture program, which was supposed to replace the larger spy satellites now being used. "The whole program has had problems" with challenging technology and contracts that were bid unrealistically low, he said. "And now this."

The National Reconnaissance Office is an arm of the Defense Department tasked with designing, building and operating spy satellites for the nation. While hundreds of these spacecraft have been launched in the past decades, few remain useful for more than several years, and so, to keep important orbits clear, they routinely are directed back to Earth. Generally, that is done with a controlled burn of a craft's remaining fuel, one that allows ground control to crash it safely into an ocean, analysts say.

In the past, the most important spy satellites were large, about 8 to 10 tons. The newer generation was supposed to be considerably smaller and lighter, making them potentially cheaper and quicker to launch.

Pike and others believe that the failed satellite was part of a controversial contract given in 1999 to Boeing, which had never built a spy satellite before, and ultimately the contract was taken from the company because of technological and financial problems.

Amateur astronomers who track satellites identified the December 2006 launch as troubled from the start. They reported that the satellite never left its low orbit for the higher one it needed and that the orbit gradually became lower.