NASA, Navy team up to shoot down runaway U.S. spy satellite
Friday, February 15th 2008, 1:10 AM
WASHINGTON - NASA and the Navy teamed up Thursday for an urgent, never-before-tried mission to shoot down a runaway U.S. spy satellite that threatens to fall to Earth with a half-ton of deadly hydrazine gas aboard.
President Bush ordered the shootdown attempt by a missile launched from a Navy Aegis cruiser "to reduce the danger to human beings," said Deputy National Security Adviser James Jeffrey.
Hydrazine gas "could, in fact, be deadly," said Marine Gen. James Cartwright. It can cause fatal lung, liver and kidney damage.
Unless the 5,000-pound satellite - about the size of a city bus - is destroyed, its gas tank, containing 1,000 pounds of hydrazine, would likely survive the fiery reentry into Earth's atmosphere, said NASA chief Michael Griffin.
"The hydrazine tank will survive intact," Griffin said. "It will land on the ground as slush hydrazine, so that hydrazine will vent."
Pentagon officials could not predict where the satellite would come down if the missile fails to hit it, but they said it was unlikely to land in a populated area. However, the debris could cover an area as large as two football fields, they said.
Cartwright said there was a "high degree" of probability that the missile will hit and break up the satellite, but he added, "This is the first time we've used a tactical missile to engage a spacecraft."
The shootdown plan is to have the missile, which lacks an explosive warhead and is designed to slam into targets, intercept the satellite just before reentry, about 130 miles up.
Missiles fired from Aegis ships have hit 12 of 14 targets in tests, "but this target will be more difficult because it will be going faster" - about 20,000 mph - said John Pike, head of globalsecurity.org, a defense watchdog group.
The launch window for firing the Standard Missile-3 anti-ballistic missile from an Aegis in the northern Pacific opens early next week and stays open for about a week, said Cartwright, the vice chairman of the Joint Chiefs of Staff.
But Griffin said the shootdown would not be attempted before the space shuttle Atlantis, currently docked with the International Space Station, lands next Wednesday to avoid having a miss endanger the astronauts.
The satellite, which belongs to the super-secret National Reconnaissance Office, went dead shortly after launch in December 2006, and ground technicians have been unable to communicate with it or control it ever since.
The satellite is believed to carry advanced-imaging radar that can see through clouds.
The largest previous uncontrolled reentry by a spacecraft was that of Skylab in 1979. Much of the debris from the 78-ton space laboratory fell into the Indian Ocean, but some harmlessly hit Australia.