Associated Press
Debris from an obliterated U.S. spy satellite is being tracked over the Pacific and Atlantic oceans but there does not appear to be enough of it to cause damage on Earth, a senior military officer said Thursday, just hours after a Navy missile scored a direct hit on the failing spacecraft.
Marine Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff and an expert on military space technologies, told a Pentagon news conference that officials have a "high degree of confidence" that the missile launched from a Navy cruiser Wednesday night hit exactly where intended.
It was an unprecedented mission for the Navy, so extraordinary that the final go-ahead to launch the missile Wednesday was reserved for Defense Secretary Robert Gates rather than a military commander.
Cartwright estimated there was an 80 percent to 90 percent chance that the missile struck the most important target on the satellite—its fuel tank, containing a thousand pounds of hydrazine, which Pentagon officials say could have posed a health hazard to humans if it had landed in a populated area.
(Related story: Is Spy Satellite's Toxic Fuel Risk Real? [February 20, 2008])
Alluding to a video clip of the missile smashing into the satellite, which he showed at the news conference, Cartwright said, "We have a fireball, and given that there's no fuel (on the tip of the missile), that would indicate that that's a hydrazine fire."
The video showed the three-stage SM-3 missile launching from the U.S.S. Lake Erie at 10:26 p.m. EST, northwest of Hawai'i, and of the missile's small "kill vehicle"—a non-explosive device at the tip—maneuvering into the path of the satellite and colliding spectacularly.
He said the satellite and the kill vehicle collided at a combined speed of 22,000 miles per hour (35,000 kilometers per hour) about 130 miles (200 kilometers) above Earth's surface. The collision was confirmed at a space operations center at 10:50 p.m. EST.
Asked about the satisfaction felt among those in the military who had organized the shoot-down on short notice by modifying missile software and other components, Cartwright smiled widely.
"Yes, this was uncharted territory. The technical degree of difficulty was significant here," Cartwright said. "You can imagine that at the point of intercept there were a few cheers that went up."
He cautioned, however, that more technical analysis was required to determine for certain what debris was created and where it might go. The satellite was described as the size of a school bus and said to weigh about 5,000 pounds (2,300 kilograms).
Unlike most spacecraft that fall out of orbit and re-enter the atmosphere, this satellite had an almost full fuel tank because it lost power and became uncontrollable shortly after it reached its initial orbit in December 2006.
