WASHINGTON — Taking a page from Hollywood science fiction, the Pentagon said Thursday that it will try to shoot down a dying, bus-size U.S. spy satellite loaded with toxic fuel on a collision course with Earth.
The military hopes to smash the satellite as soon as next week — just before it enters Earth’s atmosphere — with a missile fired from a Navy cruiser in the northern Pacific.
The dramatic maneuver may well trigger international concerns, and U.S. officials have begun notifying other countries of the plan — stressing that it does not signal the start of a new American anti-satellite weapons program.
Military and administration officials said the satellite is carrying fuel called hydrazine that could injure or even kill people who are near it when it hits the ground. That reason alone, they said, persuaded President Bush to order the shoot-down.
Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, predicted a fairly high chance — as much as 80 percent — of hitting the satellite, which will be about 150 miles up when the shot is fired. The window of opportunity for taking the satellite down, Cartwright said, opens in three or four days and lasts about seven or eight days.
“We’ll take one shot and assess,” he said. “This is the first time we’ve used a tactical missile to engage a spacecraft.”
Deputy National Security Adviser James Jeffrey discounted comparisons to an anti-satellite test conducted by the Chinese last year that triggered criticism from the U.S. and other countries.
Risk to human life cited
“This is all about trying to reduce the danger to human beings,” Jeffrey said. “Specifically, there was enough of a risk for the president to be quite concerned about human life.”
There might also be unstated military aims, some outside the administration suggested.
Similar spacecraft re-enter the atmosphere regularly and break up into pieces, said Ivan Oelrich, vice president for strategic security programs at the Federation of American Scientists. He said, “One could be forgiven for asking if this is just an excuse to test an anti-satellite weapon.”
A key issue when China shot down its defunct weather satellite was that it created an enormous amount of space debris. “All of the debris from this encounter, as carefully designed as it is, will be down at most within weeks, and most of it will be down within the first couple of orbits afterward,” said Jeffrey.
Left alone, the satellite would be expected to hit Earth during the first week of March. About half of the 5,000-pound spacecraft would be expected to survive its blazing descent through the atmosphere and would scatter debris over several hundred miles.
If the missile shot is successful, officials said, much of the debris will burn up as it falls. They said they could not estimate how much would make it through the atmosphere.
They said the largest piece to survive re-entry would be the spherical fuel tank, which is about 40 inches wide — assuming it is not hit directly by the missile.
The goal, however, is to hit the fuel tank in order to minimize the amount of fuel that returns to Earth, Cartwright said.
“A one-time deal”
Known by its military designation US 193, the satellite was launched in December 2006. It lost power, and its central computer failed almost immediately afterward, leaving it uncontrollable. It carried a sophisticated and secret imaging sensor.
A Navy missile known as Standard Missile 3 would be fired at the spy satellite in an attempt to intercept it just before it re-enters Earth’s atmosphere.
The missile’s designed mission is to shoot down ballistic missiles, not satellites, so its software will have to be modified. Other officials said the missile’s maximum range, while a classified figure, is not great enough to hit a satellite operating in normal orbits.
Officials at the North American Air Defense Command — NORAD — near Colorado Springs refused to comment on whether it would play any role in the operation.
When asked whether the modified missile should be considered a new U.S. anti-satellite technology, Cartwright replied: “It’s a one-time deal.”
NASA Administrator Michael Griffin said the hydrazine tank would survive a fall to Earth under normal circumstances, much as one did when the space shuttle Columbia crashed.
“The hydrazine which is in it is frozen solid, as it is now. Not all of it will melt,” he said. If the tank hits the ground, the fuel lines will have broken off and hydrazine will vent out, he said.
