Pentagon could down satellite today

WASHINGTON — An attempt to blast a crippled U.S. spy satellite out of the sky using a Navy heat-seeking missile — possibly tonight — would be the first real-world use of this piece of the Pentagon's missile defense network.

The attempted shootdown is seen by some as blurring the lines between defending against a weapon like a long-range missile and targeting satellites in orbit.

The three-stage Navy missile, designated the SM-3, has chalked up a high rate of success in a series of tests since 2002 — in each case targeting a short- or medium-range ballistic missile, never a satellite. A hurry-up program to adapt the missile for this anti-satellite mission was completed in a matter of weeks; Navy officials say the changes will be reversed once this satellite is down.

The government issued notices to aviators and mariners to remain clear of a section of the Pacific beginning at 10:30 p.m. EST tonight, indicating the first window of opportunity to launch an SM-3 missile from a Navy cruiser, the USS Lake Erie, in an effort to hit the wayward satellite.

Having lost power shortly after it reached orbit in late 2006, the satellite is well below the altitude of a normal satellite. The Pentagon wants to hit it with the missile just before it re-enters Earth's atmosphere, in that way minimizing the amount of debris that would remain in space.

Adding to the difficulty of the mission, the missile will have to do better than just hit the bus-sized satellite, a Navy official said Tuesday. It needs to strike the relatively small fuel tank aboard the spacecraft in order to accomplish the main goal, which is to eliminate the toxic fuel that could injure or even kill people if it reached Earth. The Navy official described technical aspects of the missile's capabilities on condition that he not be identified.

Also complicating the effort will be the fact that the satellite has no heat-generating propulsion system on board. That makes it more difficult for the Navy missile's heat-seeking system to work, although the official said software changes had been made to compensate for the lack of heat.

The Pentagon press secretary, Geoff Morrell, said Defense Secretary Robert Gates was briefed on the shootdown plan Tuesday by the two officers who will advise him on exactly when to launch the missile — Gen. Kevin Chilton, the head of Strategic Command, and Gen. James Cartwright, the vice chairman of the Joint Chiefs of Staff, who held Chilton's post until last summer.