Tonight, at 10:30 EST, Navy gunners aboard the cruiser USS Lake Erie will fire a $10 million SM3 interceptor missile that will destroy the faltering spy satellite before it can tumble to Earth and -- possibly -- release a cloud of toxic gas.
Malfunctioning immediately after it was launched in December 2006, the satellite has a full tank -- about 1,000 pounds -- of frozen, toxic hydrazine propellant.
Authorities said, without intervention, the fuel tank likely would survive re-entry and could disperse harmful or even potentially deadly fumes over an area the size of two football fields. Hydrazine is similar to chlorine or ammonia in that it affects the lungs and breathing tissue.
The goal is to strike the satellite in a low orbit, just before it re-enters the Earth's atmosphere, at an altitude of about 150 miles. The idea is to blast the satellite apart on impact so that the hydrazine tank explodes.
If the satellite is not destroyed, it is expected to make an uncontrolled re-entry into the Earth's atmosphere on or about March 6.
Not to be upstaged, nature will present a total lunar eclipse, at 10:01 EST, in a different portion of tonight's sky.
Total Lunar Eclipse Details
UPDATE: Spy Satellite Shootout Succeeds - Ongoing Story
"We have a hit!" was the radio message transmitted to the Pentagon three minutes after the missile was launched.
Several cameras trained on the satellite known as USA 193 saw it immediately reduced to a cloud of shards.