U.S. to try to shoot down falling satellite tonight

WASHINGTON – The U.S. military likely will make its first effort to shoot down a crippled spy satellite that’s approaching Earth’s atmosphere sometime after 6:30 p.m. Pacific time today, the Pentagon announced Tuesday, in what will be a major, if unplanned, test of America’s anti-ballistic missile program.

The USS Lake Erie, a Ticonderoga class missile cruiser with an Aegis weapons system, will launch an SM-3 tactical missile toward the satellite from somewhere west of Hawaii, the Pentagon said. If that missile misses, the Navy has two other missiles on standby to launch, most likely on Thursday or Friday, the Pentagon said.

A Federal Aviation Administration advisory warned airlines that the launch could happen between 6:30 p.m. and 9 p.m. Pacific time.

U.S. officials announced last week that the Navy would try to down the satellite out of concern that a tank carrying 1,000 pounds of hydrazine, an ammonia-like chemical used in rocket fuel, would survive re-entry into the Earth’s atmosphere and land in a populated area. Hydrazine can be toxic if swallowed or inhaled.

The plan, however, is controversial. Some experts have suggested that the attempt is really an effort to expand the capabilities of the anti-ballistic missile system to include satellites and to counter China’s destruction of an aged weather satellite last year. The United States denounced that Chinese test.

The missile and the roughly 5,000-pound satellite, which failed shortly after it was launched in December 2006, will close in on each other at roughly 20,250 mph, officials said.

The shootdown isn’t a sure thing. The missiles that will be used to strike the satellite were designed to bring down ballistic missiles, and their software had to be rewritten so they could target the satellite, which moves faster than a ballistic missile.

The missiles also will find tracking the satellite difficult because, without power, it will be cooler than a ballistic missile. A senior Navy official, who couldn’t be quoted by name under Pentagon press rules, said that the timing of the shootdown was chosen partly so that the afternoon sun over the Pacific could warm the satellite, making it more likely that the missile would be able to find it 150 miles above the Earth’s surface.

The timing also was dictated by the scheduled return of the space shuttle Atlantis, which is expected to land by this afternoon, said Geoff Morrell, a Pentagon spokesman. “Touchdown of the Atlantis opens the window of opportunity for the military to shoot down that rapidly decaying U.S. intelligence satellite,” he said.