The U.S. Navy has blasted a disabled spy satellite carrying a tank of toxic fuel out of the sky over the Pacific with a heat-seeking missile.
A senior defence official said that the specially-designed missile launched at the satellite, which experts feared would crash to the Earth, had destroyed the satellite's main fuel tank - making the mission a complete success.
The 5,000lb USA 193 satellite, which is about the size of a small bus, was equipped with rocket thrusters loaded with toxic hydrazine fuel.
Perfect strike: The SM-3 is launched from the US Navy destroyer USS Lake Erie this morning 
Up, up and away: Just three minutes after this photo was taken, the missile destroyed the satellite
Orbiting 130 miles above the Earth, scientists feared the satellite would crash with the fuel tank intact, causing contamination.
Earlier today the Pentagon had said it would take up to two days to determine whether the fuel tank has been destroyed - but a senior official later said all indications showed the mission had been a complete success.
Officials had been generally confident the missile would strike the bus-sized satellite, but had been worried it would miss the much smaller fuel tank.
It is the first time the US Navy has conducted a mission to shoot down a satellite and the heat-seeking missile was fired shortly after 3.30am.
U.S. Defence Secretary Robert Gates approved the missile launch last night. Within nine hours - at 10:26 p.m. EST (0326 GMT) - the USS Lake Erie fired the SM-3 missile originally designed to knock down incoming missiles rather than orbiting satellites.
We have a strike: General James Cartwright tells Defence Secretary Robert Gates of the 'hit'
It hit the satellite about three minutes later as the spacecraft travelled in polar orbit at more than 17,000 mph (27,000 kph).
The Lake Erie and two other Navy warships, as well as the missile and other components, were modified in a hurry-up project started in January. The missile alone cost nearly US$10 million (£5 million), and officials estimated that the total cost of the project was at least US$30 million (£15 million).
The operation was so extraordinary, with such intense international publicity and political ramifications, that Gates - not a military commander down the chain of command - made the decision to pull the trigger.
The government organized hazardous materials teams, under the code name "Burnt Frost," to be flown to the site of any dangerous or otherwise sensitive debris that might land in the United States or elsewhere.
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 three-stage Navy missile used for the mission has chalked up a high rate of success in a series of tests since 2002, in each case targeting a short- or medium-range ballistic missile, never a satellite.
Modifications to the missile for the mission were completed in a matter of weeks, and Navy officials said the changes would be reversed once this satellite was down.
Within hours of the reported success, China said it was on the alert for possible harmful fallout from the shootdown and urged Washington to promptly release data on the action.
"China is continuously following closely the possible harm caused by the U.S. action to outer space security and relevant countries," Foreign Ministry spokesman Liu Jianchao said at news conference in Beijing.
The satellite went off course shortly after its 2006 launch and has been orbiting out of the control of ground technicians.
A US Navy ship test fires a missile like the one used to destroy the satellite
The craft is operated by the National Reconnaissance Organization, the US agency in charge of spy satellites, which has not divulged the spacecraft's mission.
The missile attempt was approved by President George Bush, but Russia and China both voiced fears that the exercise was an excuse for the US to test missile defence systems.
Ships on the Pacific were warned to be aware of the attempt and the possibility of debris.
A senior defence official said that because the satellite was dormant and had been flying through the freezing temperatures of outer space, Navy commanders had to rely on the sun to warm the craft so that the missile being shot at it - which relies heavily on heat to find its target - could locate it.
The move - the first attempt to shoot down a satellite since Cold War tests in the 1980s - has been condemned by Russia which says the exercise is a ruse by Washington to test a new US anti-missile defence system.
China has also expressed alarm over the plan, questioning why it is necessary to carry out such a risky manoeuvre when the dangers posed by the satellite crash-landing were so slim.
Earlier this week, a spokesman for RAF Fylingdales in North Yorkshire said the satellite tracking station had not been asked to do anything specifically for this satellite.
"It's just normal business here for us tracking the 12,000 or so space objects that pass within our range on a regular basis," a spokesman said.
"In the future we may be asked, as one of many tracking facilities, to track the debris of the satellite if the US authorities are successful in shooting it down."
Left alone, the satellite would have hit Earth during the first week of March. About half of the 5,000-pound (2,200-kilogram) spacecraft was expected to survive its blazing descent through the atmosphere and would have scattered debris over several hundred miles.
Planes over the pacific have been warned. Debris from the rogue toxic satellite is expected to largely burn up on entry but some may fall over the next month Source: Daily Mail UK, Feb. 21, 2008
Bullseye! US blasts out-of-control toxic satellite with £5m heat-seeking missile 
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