WASHINGTON
(AP) — Debris from an obliterated U.S. spy satellite is being tracked over the
Pacific and Atlantic oceans but appears to be too small 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 1,000
pounds of hydrazine, which Pentagon officials say could have posed a health
hazard to humans if it had landed in a populated area.
Cartwright
showed a brief video of the SM-3 missile launching from the USS Lake Erie at
10:26 p.m. EST, northwest of Hawaii, 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 mph about
130 miles above Earth's surface.
Asked about
the satisfaction felt among those in the military who had organized the
shootdown 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 weighed about 5,000 pounds.
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. Cartwright said
the hydrazine alone was justification for undertaking the unprecedented effort
to use a Navy missile interceptor to attempt to destroy the satellite in orbit.
Cartwright
said experts were still watching the debris fields and he could not yet rule
out that hazardous material would fall to Earth. But he indicated that this
appeared unlikely to pose a problem.
"Thus
far we've seen nothing larger than a football," he said, referring to
debris spotted by radars and other sensors.
The
military concluded that the missile had successfully shattered the satellite
because trackers detected a fireball, which seemed to indicate the exploding
hydrazine in the tank. Cartwright said it was unlikely that the fireball could
have been caused by anything other than the hydrazine. Also, a vapor cloud was
detected, further suggesting the destruction of the fuel, Cartwright said.
Debris from
the satellite has started re-entry and will continue through Thursday and into
Friday, Cartwright said.
The size of
the debris is smaller than the Pentagon had forecast and most of the
satellite's intelligence value was likely destroyed, Cartwright said. Analysts
had said one of the reasons for the shootdown was that officials worried that without
it, larger chunks of the satellite could fall and be recovered, opening the
possibility of secret technology falling into the hands of the Chinese or
others.
Gates
arrived in Hawaii less than two hours before the missile was launched. His
press secretary, Geoff Morrell, said Gates had a conference call during his
flight with Cartwright and Air Force Gen. Kevin Chilton, head of Strategic
Command. They told him that "the conditions were ripe for an attempt, and
that is when the secretary gave the go-ahead to take the shot, and wished them
good luck," Morrell said.
At 10:35
p.m. EST, Gates spoke to both generals again and "was informed that the
mission was a success, that the missile had intercepted the decaying satellite,
and the secretary was obviously very pleased to learn that," said Morrell.
The
elaborate intercept may trigger worries from some international leaders, who
could see it as a thinly disguised attempt to test an anti-satellite weapon —
one that could take out other nations' orbiting communications and spy
spacecraft.
Within
hours of the reported success, China said it was on the alert for possible
harmful fallout from the shootdown and urged Washington to promptly release
data on the action.
"China is continuously following closely the possible harm caused by the U.S. action to outer space
security and relevant countries," Foreign Ministry spokesman Liu Jianchao
said at news conference in Beijing. "China requests the U.S. to fulfill its international obligations in real earnest and provide to the
international community necessary information and relevant data in a timely and
prompt way so that relevant countries can take precautions."
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