U.S. Officials Say Broken Satellite Will Be Shot Down
By DAVID STOUT and THOM SHANKER
WASHINGTON — The Pentagon plans to shoot down a disabled 5,000-pound spy satellite before it enters the atmosphere in early March, a senior Pentagon official said Thursday.
The official said the operation was expected to be carried out from a Navy cruiser that would fire a missile specially fitted for the mission. Other details on the timing and location of the operation were not available, pending a Thursday afternoon briefing at the Defense Department. Navy ships routinely carry missiles to shoot down aircraft.
It was not immediately known if the operation was prompted by fears that the satellite’s debris would pose a danger if the satellite were allowed to tumble back into the atmosphere on its own; by reasons of secrecy, or by some combination of factors.
Many satellites have fallen harmlessly out of orbit during the space age, in part because they often break apart and the pieces generally burn upon re-entry. And when pieces do survive re-entry, they have usually landed in remote areas or in an ocean, simply because the Earth’s surface has more remote regions and seas than it does heavily populated areas.
The operation, which was first reported on Thursday by The Associated Press, involves the Department of Homeland Security, the State Department and other agencies in addition to the Defense Department.
The ramifications of the operation are diplomatic as well as military and scientific, in part because the United States criticized China last year when Beijing used a defunct weather satellite as a target in a test of an antisatellite system.
After their test, the Chinese said that they had no intention of getting involved in a “space race,” and that their test had not been designed to intimidate. Under the Bush administration, the United States has asserted its need to protect its interests in space.
The United States shot down a satellite in September 1985, as a test of an antisatellite system under development. In that experiment, an F-15 Eagle fighter aircraft fired a missile armed with a “kill” vehicle that collided with the U.S. Solwind satellite.
The impending demise of the American spy satellite has been of some concern to rocket experts, who have speculated that the object may contain hydrazine fuel, which is typically used in thrusters for rocket maneuvers in space and would be hazardous to anyone who came into contact with it on the ground, should any of the substance not be consumed by the fierce heat of re-entry.
“Appropriate government agencies are monitoring the situation,” Gordon Johndroe, a spokesman for the National Security Council, said in a statement in late January, when the problem satellite was moving in a circular orbit about 170 miles above the Earth. In the previous month, its orbit had declined as much as 12 miles.
Specialists who follow spy satellite operations have speculated that the problem satellite is an experimental imagery device built by Lockheed Martin and launched from Vandenberg Air Force Base in California aboard a Delta II rocket. Shortly after it reached orbit, ground controllers lost the ability to control it and were unable to regain communication.
“Not necessarily dead, but deaf,” as Jonathan McDowell, an astronomer at the Harvard-Smithsonian center for Astrophysics, put it in late January.
John E. Pike, the director of Globalsecurity.org in Alexandria, Va., said in January that assuming the satellite in question was indeed a spy satellite, it would probably not contain any nuclear fuel, but that it could contain toxins, including beryllium, often used as a rigid frame for optical components. Moreover, it is possible that any surviving debris could be scattered over several hundred square miles.
If the satellite is destroyed before plummeting to earth, there would be less chance of sensitive American technology being compromised, Mr. Pike said. “We are worried about something showing up on e-Bay,” he told The A.P.
As for the possibility that debris could strike a population center, Mr. McDowell said in January that “one could say we’ve been lucky so far.”
The largest uncontrolled re-entry by an American spacecraft was that of Skylab in 1979. Controllers changed the 78-ton abandoned space station’s orientation to vary atmospheric drag to shift its entry point. Much of the craft fell into the Indian Ocean, as predicted, but some pieces traveled farther than expected, falling harmlessly in Western Australia.
http://www.nytimes.com/2008/02/14/s...tellite.html?hp
ראשי
צ'אט
26-01-2008, 23:33
)
מצב כלאיים
