It's a 5,000 pound defective spy satellite that in weeks could enter Earth's atmosphere.

And with the threat of 2,800 pounds of debris and toxic fumes raining down on land, the Department of Defense is preparing for a mission-- the first of its kind.

"This operation is designed to alleviate a threat to human beings on this planet," said Pentagon Press Secretary Geoff Morrell.

As soon as Wednesday, a modified missile will be launched from the Pearl Harbor based USS Lake Erie. It's somewhere in the Pacific Ocean, Northwest of Hawaii.

Right now, about 300 Hawaii-based sailors are awaiting orders from the secretary of defense on when to take aim.

The missile will have to travel 150 miles outside of the earth's atmosphere to hit its target.

The bull's-eye? The satellite's hydrazine tank holding 1,000 pounds of toxic fuel. But it won't happen until space shuttle Atlantis is out of harms way.

"It could happen anytime the shuttle touches down and the shuttle is scheduled to touch down at 9:07 EST tomorrow [Wednesday]," said Air Force Lt. Col. Karen Finn.

The window to launch lasts only until the end of February. But officials believe the Navy has an 80 percent chance of hitting it on its first try.

The Pentagon said the mission does not pose any threat to Hawaii residents and pilots and boaters have been warned.

"General Cartwright and the commander of strategic command, General Chilton, supported by a slew of other experts across the military services and, indeed, the U.S. government, are evaluating the situation and will advise the secretary when they have a shot to take," said Morrell.

The Pentagon said it will alert the media an hour before the launch. And then afterwards announce whether the missile successfully hit the satellite.

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