The window of opportunity to shoot down a dying spy satellite is now open, right after the landing of space shuttle Atlantis, the Pentagon said on Wednesday.

"We're now into the window," a senior Pentagon official told a news conference shortly after space shuttle Atlantis landed at Kennedy Space Center in Florida at 9:07 A.M. EST (1407 GMT) on Wednesday.

 
This photo released by the US Navy in 2003 shows a Standard Missile-3 (SM-3) launching from the Aegis cruiser USS Lake Erie. The US warship is moving into position to try to shoot down a defunct US spy satellite as early as Wednesday before it tumbles into the Earth's atmosphere, Pentagon officials said Tuesday. (Xinhua/AFP Photo)

The US Navy may take the action as early as Wednesday night, US medias reported. However, the Pentagon official said the unfavorable weather at northern Pacific may postpone the shoot-down into Thursday.

"We don't anticipate the weather to be good enough," the official said, speaking on condition of anonymity. Currently no final decision has been made to call off Wednesday's opportunity.

Marine General James E. Cartwright, vice chairman of the Joint Chiefs of Staff, told reporters last week the window of opportunity for shooting down the satellite would last seven or eight days. The US military is evaluating the situation real-time.

Cartwright, Air Force General Kevin P. Chilton, commander of US Strategic Command, and other experts across the military and US government "will advise the defense secretary when they have a shot to take," Pentagon Press Secretary Geoff Morrell said on Tuesday.

The US Federal Aviation Administration is issuing notices every 24 hours during the anticipated shoot-down window, warning aircraft and ships to steer clear of the projected shoot-down zone in the Pacific.

The Pentagon announced last week the plan to shoot down the malfunctioning US spy satellite just above the atmosphere, because the satellite could cause death or injury if it fell in a populated area. Of particular concern is that the satellite could release hydrazine, a toxic chemical used as a maneuvering fuel.

The US Navy has prepared for the mission by modifying three SM-3 missiles aboard Aegis ships to strike the satellite, Cartwright said last week.

Morrell said again on Tuesday that the mission isn't designed to test US anti-satellite capabilities. "This operation is designed to alleviate a threat to human beings on this planet. There is a large tank of hydrazine fuel onboard that satellite that would pose a significant threat to people within the immediate vicinity of it if it were to hit land."?

(Xinhua News Agency February 21, 2008)