Spy satellite to plummet to Earth
A "large" US spy satellite has gone out of control and is expected to crash to Earth sometime in late February or March, government sources say.
Officials speaking on condition of anonymity said the satellite had lost power and propulsion, and could contain hazardous materials.
A spokesman from White House said "numerous" satellites had come out of orbit and fallen back to Earth harmlessly over the years.
"We are looking at potential options to mitigate any possible damage this satellite may cause," said Gordon Johndroe, who speaks for the US National Security Council.
Fuel hazard
The satellite contains the rocket fuel hydrazine, a government official told AP on condition of anonymity.
A colourless liquid with an ammonia-like odour, the fuel is a toxic chemical and can cause harm to anyone who comes in contact with it.
John Pike, director of the defence research group GlobalSecurity.org, said an uncontrolled re-entry could risk exposure of US secrets.
Spy satellites typically are disposed of through a controlled re-entry into the ocean so that no one else can access the spacecraft, he was quoted by AP as saying.
The military expert believes that shooting the satellite down would create debris that would then re-enter the atmosphere and burn up or hit the ground.
In his estimate, the satellite weighs about 20,000 pounds (9,000kg) and is the size of a small bus.
It is possible, he adds, that this one died as long as a year ago and is just now getting ready to re-enter the atmosphere.
Another expert, Jeffrey Richelson of the National Security Archive, said the satellite was probably a photo reconnaissance satellite.
Into the ocean
AP notes that the largest uncontrolled re-entry by a US space agency (Nasa) craft was Skylab.
The 78-tonne abandoned space station fell from orbit in 1979.
Its debris dropped harmlessly into the Indian Ocean and across a remote section of western Australia, the US news agency says.
In 2002, officials believe debris from a 7,000lbs (3,200kg) science satellite hit the Earth's atmosphere.
It rained down over the Gulf, a few thousand miles from where they first predicted it would crash.
MISSILE DEFENCE WORKS
The US defence secretary has said that the shooting down of a disabled spy satellite with a missile shows the country's missile defence system works.
Robert Gates said the operation "speaks for itself", adding the US was prepared to share some technology with China.
The comments came after China said the missile strike could harm security in outer space.
US officials are confident that the satellite's potentially toxic fuel tank was destroyed by the missile.
Marine Gen James Cartwright said there was a 80-90% chance the tank had been hit.
A fire ball, vapour cloud and spectral analysis indicating the presence of hydrazine all indicated this, he told reporters.
Frozen solid
Operatives had only a 10-second window to hit the satellite, which went out of control shortly after it was launched in December 2006.
The missile needed to pierce the bus-sized satellite's fuel tank, containing more than 450kg (1,000lbs) of toxic hydrazine, which was otherwise expected to survive re-entry.
The US denies the operation was a response to an anti-satellite test carried out by China last year, which prompted fears of a space arms race.
US officials had said that without an attempt to destroy the fuel tank, and with the satellite's thermal control system gone, the fuel would have been frozen solid, allowing the tank to resist the heat of re-entry.
If the tank were to have landed intact, it could have leaked toxic gas over a wide area - harming or killing humans if inhaled, officials had warned.
The US has denied that it shot down the satellite to prevent parts of it from falling into the hands of foreign powers.
Gen Cartwright said most of the satellite's intelligence value was likely to have been destroyed.
Marine Gen James Cartwright said there was a 80-90% chance the tank had been hit.
It would take 24-48 hours for officials to confirm whether the operations had been completely successful, he said.
No comments:
Post a Comment