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. "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

 Source : CNN.com