A pair of local astronomers have headed to the Haleakala Summit on Maui today on the slight chance they'll be able to see the explosion of the wayward U.S. spy satellite through their telescope.

"It's going to be difficult to see if it happens because it is happening in the west around sunset," said JD Armstrong, Maui technology education and outreach specialist with the UH Institute for Astronomy. "If it reaches its maximum brightness, about minus 1.8 magnitude, it will be brighter than any star in the sky. If it reaches just 1.4 magnitude, it will be only as bright as the most visible star in the sky. Because of it's location and timing, it's going to be diffcult to see at best."

Armstrong and Rob Ratkowski of the Haleakal Amateur Astronomers group have calculated the satellite's orbit and said the U.S. military will be shooting it down at 5:26 p.m, weather permittiing.

Earlier today it was reported that rough seas may delay the shooting. Pentagon officials declined comment this afternoon on whether it would launch heat-seeking missiles at the satellite or wait another day. A military spokesman said the Department of Defense will issue an update about an hour after the shoot if it goes off, but nothing beforehand.

The USS Lake Erie, a cruiser armed with two SM-3 missiles, will be firing the shot at the satellite.

The attempted shoot-down was approved by President Bush last week out of concern that toxic fuel on board the satellite could crash to Earth and potentially harm humans, the Defense Department has said.

According to Associated Press reports, officials will know within minutes of the SM-3 missile launch whether the missile has hit the satellite, but it will take a day or two to know whether the fuel tank has been destroyed.

The military has readied a three-stage Navy missile, designated the SM-3, which has chalked up a high rate of success in a series of missile defense tests since 2002. In each case it targeted 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 Ocean beginning at 5:30 p.m. Hawai'i time Wednesday, indicating the first window of opportunity to launch an SM-3 missile from 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 out of control and well below the altitude of a normal satellite. The Pentagon wants to hit it with an SM-3 missile just before it re-enters Earth's atmosphere, in that way minimizing the amount of debris that would remain in space.

Left alone, the satellite would be expected to hit Earth during the first week of March. About half of the 5,000-pound spacecraft would be expected to survive its blazing descent through the atmosphere and would scatter debris over several hundred miles.

Adding to the difficulty of the shoot-down 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.