The U.S. military, using a missile from one of its Navy ships, will likely try to shoot down a failed spy satellite(用从海军舰艇发射的火箭击落退役的间谍卫星) Thursday, two officials familiar with the planning told us.
The satellite 卫星
A Delta II rocket carrying a reconnaissance satellite launched December 14, 2006, from Vandenberg Air Force Base in California. The 5,000-pound satellite stopped working within hours after reaching orbit and has not responded to attempts to communicate with it, authorities said. Without intervention, officials believe that the spacecraft will come down on its own in March.The satellite is carrying approximately 1,000 pounds of frozen hydrazine propellant, according to the U.S. military. Because the chemical can be toxic to human lungs and breathing tissue, the military said it will try to shoot down the satellite and make the hydrazine tank explode before the satellite enters Earth.
The missile 火箭
The military said it plans to shoot down the satellite using the Standard Missile 3(美国海军标准2型火箭), a U.S. Navy missile, which will be launched from the Navy's USS Lake Erie, pictured. Changes have been made to the software associated with the missile to increase the odds of its sensors identifying the satellite as its target; the missile was designed to shoot down ballistic missiles, not satellites.
Shooting down the satellite击落卫星过程
This animation gives a projection of the shootdown mission, which is estimated to cost $40 million to $60 million(花费约4000-6000万美元), according to the Missile Defense Agency.The USS Lake Erie, an Aegis cruiser, will fire a missile from a spot in the northern Pacific Ocean while a trajectory comes from a second ship. A third ship will be used as a backup, U.S. Navy officials said.Marine Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, predicted a chance of up to 80 percent that the missile will hit the satellite.
Satellite orbit卫星轨道
The satellite is expected to be about 150 miles high, or just above Earth's atmosphere, when the missile is launched. A successful hit will blast the satellite into smaller debris that will burn up in the atmosphere as it falls back to Earth over the next few weeks, officials said. If the missile does not hit the satellite, the largest piece that will survive re-entry is the fuel tank, which is about 40 inches wide.U.S. officials criticized China last year for shooting down a defunct weather satellite orbiting more than 500 miles above Earth. The impact created space debris that will remain in orbit for decades, according to the U.S. State Department, threatening other satellites and spacecraft -- including the international space station, pictured -- in its path.
[本帖最后由 wind 于 2008-2-19 13:07 编辑]