( dpa ) - The US military expressed confidence Thursday that the missile strike against a failed spy satellite succeeded in destroying a hazardous fuel tank that could have posed a danger to humans if the spacecraft re-entered Earth's atmosphere.
Marine General James Cartwright, the vice chairman of the Joint Chiefs of Staff, said there was a "high degree of confidence" the tank carrying a toxic fuel called hydrazine was ruptured, but another one to two days of analysis was required to be certain.
Cartwright said the Pentagon spotted a vapour cloud that erupted following the collision in low orbit over the Pacific Ocean, and pictures that show the missile hit near the tank were solid evidence the tank was destroyed.
"By all indications, we're on a positive path that this was a successful intercept," Cartwright said, but added the Pentagon was not "at a point where we are ready to say for sure."
The Navy fired an unarmed missile to take out the rogue satellite before it was to re-enter the Earth's atmosphere in the first week of March. The Pentagon was worried the fuel could harm humans if it landed in a populated area.
President George W Bush authorized the shoot-down of the satellite to minimize the threat, but the act prompted protests from Russia and China, who argued the controversial operation could be seen as a test of the US missile-defence system's ability to hit satellites.
The USS Lake Erie near Hawaii fired a missile at 10:26 pm Wednesday (0326 GMT Thursday) that struck the satellite minutes later at a speed of 27,000 kilometres per hour and at an altitude of 247 kilometres.
The successful hit will be viewed as a major accomplishment for the sea-based missile defence system, which was built to counter medium-range threats and has in testing been among the Pentagon's more reliable missile defence programmes.
Officials expect most of the debris to burn up while re-entering the atmosphere. The Pentagon wanted to avoid the possibility of the satellite's debris returning to a high orbit and posing a threat to other objects in space. Cartwright said the debris spotted since the collision indicate the satellite was broken into small pieces.
"Right now we're seeing nothing bigger than a football," Cartwright said.
The US military opened a window beginning Wednesday in hoping to launch a missile to shoot down the satellite, despite earlier concerns about poor weather that caused rough waters around the firing vessel.
The satellite lost communication shortly after it was launched in 2006 and has since wandered aimlessly in orbit. It had over time begun a descent toward Earth and the White House opened up the possibility of shooting it down earlier this year.
The Pentagon estimated that it would have until the end of February to shoot down the satellite but waited to fire until the return of the Space Shuttle Atlantis early Wednesday at Cape Canaveral, Florida.
The Pentagon was concerned that once the satellite fell into re- entry in March, it would not be possible for the missile defence system to track it for a missile strike.
China and Russia protested the launch would mark a step toward the militarization of space and signalled a broader mission for the US missile-defence system. The sea-based Aegis version of missile defence was deployed by the Navy to strike the satellite. China a year ago used a land-based missile to shoot down one of its old weather satellites, which was in much higher orbit than the US satellite, leaving thousands of chunks of debris in orbit that will have to be monitored for years. The US strike against the satellite in low orbit means most of the debris will burn up in the atmosphere within weeks, officials said.
China, however, on Thursday restated its complaints about the US operation. A spokesman for the Foreign Affairs Ministry, Liu Jianchao, said Beijing was worried about potential damage from the destruction and the possible ramifications for security in space.
The United States should provide the international community with information "promptly" so "relevant countries can take precautions." Cartwright said the Pentagon was supplying the State Department with information to pass on to its embassies so it can be shared with other countries.
"If anybody has any questions, we'll answer those on a case-by- case basis," State Department spokesman Sean McCormack.
John Rood, the acting US undersecretary for arms control, met with Russian Deputy Foreign Minister Sergei Kislyak in Budapest for talks on US plans to base long-range missile defences in Poland and the Czech Republic. But they also discussed the satellite operation.
"We had a full exchange on the subject, we have shown transparency and explained our reasons for the action," Rood told reporters. Moscow strongly opposes the deployment of the system to Eastern Europe and the dispute has largely been behind deteriorating US- Russian relations.
The USS Lake Erie, a Ticonderoga-class cruiser, fired a Standard Missile-3, which used thermal image sensors to seek out the satellite and computer-guided thrusters to stay on course. When the satellite mission arose, the Navy rushed to adjust three of its missiles to hit a satellite target rather than an enemy missile; only one was needed.
The Standard Missile does not carry explosives, instead colliding with targets at high speeds.
Experts have suggested that the US military could have used the satellite to test the adaptability of its missile defence system for taking out satellites or to prevent sensitive technologies on the satellite from ending up in the wrong hands.
The United States had not tested an anti-satellite weapon since 1985.