Editor's Note: Updating from an earlier post:
By Jim Miklaszewski, NBC News Chief Pentagon Correspondent
President Bush has personally authorized the U.S. military to launch a surface-to-air missile to destroy a disabled spy satellite that is orbiting out of control and is expected to reenter the atmosphere and crash to earth within the next several weeks. This is the first time the U.S. military will attempt to shoot down an orbiting satellite with a tactical missile.
In a Pentagon briefing, White House, Pentagon and NASA officials said the decision was made primarily because the 1,000 pounds of hydrazine fuel on board presented a potential danger to people on the ground. The officials said the hydrazine fuel tank would likely be the largest piece of satellite debris that hits the ground, about 40 inches in diameter. The hydrazine fuel, frozen in space, would turn to slush by the time it hit the ground, and as it melted would give off toxic fumes that could affect an area of "a couple hundred yards." That means, they explained, that anyone within a hundred yards on each side of the fuel tank could suffer lung damage, or, with prolonged exposure, be killed.
The officials claimed that any top-secret optics or imagery equipment on board would be destroyed even during an uncontrolled entry, and this would not fall into the hands of rival nations. Destruction of that sensitive material is not the reason for the missile intercept, they said.
According to the officials, an SM-3, three-stage tactical missile would be fired from a Navy ship in the Pacific, in an attempt to intercept and destroy the missile as it begins to reenter the atmosphere 130 nautical miles above the earth. Ideally, the missile would slam into the satellite at a closing speed of 22-thousand miles per hour, break it apart and disperse the hydrazine fuel in the upper atmosphere. If the missile nicks the satellite, it would cause it to tumble even more violently when it reentered the atmosphere, increasing the odds the missile would fly apart. If the missile misses, the Navy would have two other missiles on board ships and the military would reassess whether they should take a second, or even third shot at the satellite as it comes around in subsequent orbits.
The officials say that destroying the satellite as it reenters the atmosphere will all but eliminate any "space junk" debris that would present a hazard in space, because virtually all the pieces would reenter the earth in smaller chunks within a couple orbits.
The officials put the likelihood of hitting and destroying the satellite at 80-90 percent.
US officials tell NBC News the window for opportunity to shoot down the satellite will open on Thursday, February 20, and remain open for about 10 days.
