The SM-3 missile fired from a U.S. Navy warship hit the failing satellite over the Pacific Ocean thus preventing it from falling from the orbit and crashing to Earth with its toxic fuel tank, the Pentagon said Wednesday.

"The missile's been launched and [it was] a successful intercept," the Pentagon source emphasized.

The main objective of this mission was not only to hit and destroy the satellite which was the size of a bus, but also to destroy a tank aboard the spacecraft carrying 1,000 pounds of hydrazine, which is a highly toxic substance used in rocket fuels and to prepare the gas precursors used in air bags. The fuel aboard the satellite would have posed a potential health hazard to humans if it had landed in a populated area.

Although the chance that the satellite would crash in a highly populated area is very low, the Pentagon wanted to eliminate even that minor risk.

However, the Navy officials also said that they wouldn't know until Thursday whether the mission was a complete success.

The Pentagon official said the monitoring panel saw what appeared to be an explosion which indicated that the fuel tank was hit.

The missile that hit the failing satellite was a SM-3, which is a rocket designed to knock down incoming missiles, not incoming satellites. The SM-3 was launched from the warship Lake Erie at 10:26 p.m. New York time. The missile traveled with a speed of more than 17,000 mph and it took three minutes to hit the target.

The operation began just after the space shuttle Atlantis landed Wednesday in Florida. The best time to attempt the shot was late afternoon local time because at that time the satellite would have had maximum exposure to the sun. The sun would have warmed the satellite enough so the heat-seeking SM-3 to track and destroy it.

Even if the fuel tank wasn’t obliterated, the explosion would reduce the risk by breaking the satellite into smaller pieces that will be destroyed before entering the Earth's atmosphere.

"Nearly all of the debris will burn up on reentry within 24-48 hours and the remaining debris should reenter within 40 days," the statement released by the Pentagon said.