WASHINGTON (CNN) -- Pentagon officials said they think a Navy missile scored a direct hit on the fuel tank of an errant spy satellite late Wednesday, eliminating a toxic threat to people on Earth.
The USS Lake Erie launches a missile as the satellite travels over the Pacific Ocean.
"We have a high degree of confidence we got the tank," Marine Gen. James Cartwright said at a Pentagon briefing Thursday morning.
A fireball and a vapor cloud seen after the strike appeared to indicate the toxic hydrazine fuel had been destroyed, he said. The missile that struck the satellite did not carry an explosive warhead.
Cartwright also said the satellite seemed to be reduced to small pieces.
"Thus far, we see nothing larger than a football," he said.
The military was analyzing data from the strike to confirm that the tank was hit and that no larger pieces of debris escaped detection, Cartwright said.
The missile that struck the satellite was launched from the ballistic missile defense cruiser USS Lake Erie from the Pacific Ocean west of Hawaii at 10:26 p.m. ET Wednesday, the general said. Breakup of the satellite more than 130 miles above was confirmed 24 minutes later, Cartwright said. Watch as the general explains how debris will be monitored »
Cartwright said the Navy took its first opportunity to hit the satellite and acted before days of expected bad weather may have prevented a missile launch.
Cartwright said debris from the satellite was burning up in the atmosphere over the Atlantic and Pacific oceans. This process was expected for the next day or so. Watch a report on the shootdown »
Officials had said the missile would not be fired until the space shuttle Atlantis landed, which it did Wednesday, to ensure debris from the destroyed satellite didn't strike the shuttle.
The satellite was launched in December 2006. It lost power and its central computer failed almost immediately afterward, leaving it uncontrollable. The satellite carried a sophisticated and secret imaging sensor.
Because it malfunctioned immediately after being launched, it had a full tank -- about 1,000 pounds -- of frozen, toxic hydrazine propellant.
Without intervention, the satellite would have fallen to Earth in early March, officials said. Watch how the failing satellite failed to spark fears »
The fuel tank might have survived re-entry if the satellite had fallen to Earth on its own. It could have dispersed harmful or even potentially deadly fumes over an area the size of two football fields. Hydrazine is similar to chlorine or ammonia in that it affects the lungs and breathing tissue.
But some analysts said the Pentagon had reasons other than safety for bringing down the satellite.
"The spy agency doesn't want some part of the satellite to fall into the wrong hands," Philip Coyle, a former assistant secretary of defense, told SPACE.com.
The Web site also reported that Coyle said the shootdown allowed the Pentagon to show off U.S. missile defense capabilities and to prove to China "we can shoot down a satellite in a test without creating a lot of debris like they did."
The Chinese military destroyed an aging weather satellite last year.
James Jeffrey, deputy national security adviser, denied the allegation that the U.S. was flexing its military muscle. "This is all about trying to reduce the danger to human beings," he said.
But Beijing appears to have doubts.
"China is continuing to closely follow the possible harm caused by the U.S. action to outer space security and relevant countries," Foreign Ministry spokesman Liu Jianchao said Thursday.
"China further requests that the United States ... promptly provide to the international community the necessary information ... so that relevant countries can take precautions."
Later Thursday, U.S. Defense Secretary Robert Gates said the Pentagon would share some information on the shootdown with China.
In January 2007, China used a land-based missile to destroy a 2,200-pound satellite that was orbiting 528 miles above the Earth. The impact left more than 100,000 pieces of debris orbiting the planet, NASA estimated -- 2,600 of them more than 4 inches across. The U.S. agency called the breakup of the Fengyun-C satellite the worst in history.
In 1989, a U.S. fighter jet destroyed an American satellite by firing a modified air-to-air missile into space from an altitude of 80,000 feet. That move adds to evidence the U.S. acted Wednesday strictly to guard against the prospect of a potential disaster, Cartwright said.
The military timed its shootdown attempt so that resulting debris would tumble into the atmosphere and not interfere with other satellites, said Christina Rocca, a U.S. diplomat and expert on disarmament. Her comments were included in an online U.N. report on this month's Conference on Disarmament in Geneva, Switzerland. See dangers and possible solutions to the satellite problem »
The military also timed its efforts to minimize the chances that debris would hit populated areas. But the United States is "prepared to offer assistance to governments to mitigate the consequences of any satellite debris impacts on their territory," according to a report of Rocca's remarks on the Web site of the Geneva office of the United Nations. E-mail to a friend
CNN's Suzanne Malveaux, Jamie McIntyre and Miles O'Brien contributed to this report.
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