WASHINGTON (CNN) -- The U.S. Navy likely will make its first attempt to shoot down a faulty spy satellite Wednesday night.
A Delta II rocket lifts off in December, carrying a reconnaissance satellite that failed hours later.
The U.S. government issued a formal notice warning ships and planes to stay clear of a large area of the Pacific Ocean west of Hawaii.
The notice says the two- and-a-half hour window begins 2:30 a.m. Thursday Greenwich Mean Time, which is 9:30 p.m. Wednesday on the East Coast, and 4:30 p.m. Wednesday in Hawaii.
The timing is also after the U.S. space shuttle Atlantis is scheduled to be safely on the ground.
Pentagon officials caution that the notice reflects the first opportunity to take a shot at the satellite, but it's possible the attempt could be delayed until later. Watch Pentagon spokesman Jeff Morrell describe the launch window
"We have to make the notification, but it's possible the conditions won't be ideal, or that everything won't be ready," said a Pentagon official who asked not to be identified.
Pentagon officials says if the first attempt to hit the satellite fails, there may be time for a second attempt, but that would only come after an assessment that would be hours or even days after the first attempt.
Because the 5,000-pound satellite malfunctioned immediately after launch in December 2006, it has a full tank of fuel. It would likely survive re-entry and disperse potentially deadly fumes over an area the size of two football fields, officials have said.
The Navy plans to fire at the satellite as it enters Earth's atmosphere at an altitude of about 150 miles.
Officials want the missile to hit the edge of the atmosphere to ensure debris re-enters and burns up quickly.
The Missile Defense Agency estimated the cost of a sea-based attempted intercept at $40 million to $60 million.
Without any intervention, Pentagon officials have said they believe the satellite would come down on its own in early March.
The option of striking the satellite with a missile launched from an Aegis cruiser was decided upon by President Bush after consultation with several government and military officials and aerospace experts, said Deputy National Security Adviser James Jeffrey.
"If we miss, nothing changes," said NASA administrator Michael Griffin. "If we shoot and barely touch it, the satellite is just barely in orbit" and would still burn up somewhat in the atmosphere, he said.
"If we shoot and get a direct hit, that's a clean kill and we're in good shape," he added. E-mail to a friend
CNN Senior Pentagon Correspondent Jamie McIntyre contributed to this report.
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