U.S. could shoot down satellite overnight Wednesday

WASHINGTON (Reuters) - The U.S. Navy may make its first attempt to shoot down an errant spy satellite loaded with toxic fuel overnight on Wednesday in an area of the Pacific Ocean west of Hawaii, according to U.S. officials and government documents.

A notice to mariners broadcast by the National Geospatial Intelligence Agency warned of "hazardous operations" in the area between 9:30 p.m. EST on Wednesday and midnight EST on Thursday.

The Federal Aviation Administration issued a similar notice to airmen.

Officials, who spoke on condition of anonymity, said the notices were intended to clear the area of shipping and air traffic during what could be an initial attempt to down the bus-sized satellite from a U.S. Navy ship in the Pacific.

Pentagon spokesman Geoff Morrell told reporters no decision about when to attempt the shootdown has yet been made.

But he said the first attempt would follow the scheduled landing of the space shuttle Atlantis at the Kennedy Space Center in Florida on Wednesday at 9:06 a.m. EST.

"The window of opportunity ... opens as soon as the shuttle is safely on the ground. At that point, we begin to look at when is the best time to take a shot to bring down this dying satellite," he said at a Pentagon briefing.

A Navy official said the satellite poses several challenges for U.S. ballistic missile defense because it is traveling far faster than the targets the system was designed to attack and will provide less of a heat target for infrared sensors.

Some analysts, citing defense sources, have said the Pentagon may even wait until as late as March to try to down the 5,000-pound (2,270-kg) satellite.

The notice to mariners also laid out alternatives -- each day this week through Monday during the same 9:30 p.m. EST on Wednesday and midnight EST on Thursday time-frame.

The Pentagon expects to announce the missile firing publicly within an hour of the event. But Morrell said it could take a day or more to determine whether the missile successfully destroys the satellite's fuel tank, which contains the chemical hydrazine.

The Pentagon revealed last week that President George W. Bush decided to have the Navy try to shoot down the satellite because of the danger that its fuel tank could leak deadly toxic gas if it enters the atmosphere and reaches Earth.

The satellite would be unlikely to strike a populated area but the craft's hydrazine fuel could pose a threat to life if it did, officials said.

The Navy hopes to strike the missile with a nonexplosive "kinetic kill vehicle" just before the satellite reaches the atmosphere and drive it into ocean waters, about 150 miles (240 km) above the Earth's surface.

The satellite has been out of touch since shortly after reaching its low-Earth orbit.