When the U.S. Navy announced yesterday its plans to shoot down satellite US 193, some had their doubts.  The dead satellite was the size of a school bus and completely cold, masking it from traditional missile tracking technologies.  Furthermore, the planned impact would have a combined velocity of around 22,000 mph, calling for utmost precision.

The target was a mere 4-6 ft patch on the massive satellite -- the fuel tank containing the toxic Hydrazine.  The mission was a true test of the U.S. progress in missile defense against intercontinental ballistic missiles (ICBMs) and other space based threats.

The U.S. Navy came through solidly; announcing that the first missile fired made a solid hit on the plummeting satellite.  The modified Standard Missile 3 (SM-3) launched at just before 10:26 pm EST from the deck of the U.S.S. Lake Erie, an Aegis-equipped cruiser.  The missile hurtled upwards out of the atmosphere at a speed of 5,000 mph.  At a height of 247 kilometers above the earth, it slammed into the satellite, scoring a clear hit.  The missile carried no payload so it relied on sheer kinetic energy to provide its stopping power.

The only downside is that the Department of Defense was unable to determine whether the missile hit its intended target on the satellite.  Several officials did state to the Associated Press that they believe the fuel tank was hit.  The status of the tank will be known for certain in 24 hours, when the satellite's debris begins to rain into the atmosphere.  The Department of Defense stated, "Debris will begin to re-enter the Earth's atmosphere immediately.  Nearly all of the debris will burn up on re-entry within 24-48 hours and the remaining debris should re-enter within 40 days."

The Pentagon says that any hit, whether on the fuel tank or elsewhere is better than doing nothing, as it lessens the risk of the fuel tank surviving the fall and releasing a toxic chlorine-like cloud in a populated area.  Adm. Mike Mullen, chairman of the Joint Chiefs of Staff voiced this sentiment to reporters in Pearl Harbor, Hawaii, saying, "Any kind of hit provides a much better outcome than doing nothing at all."

The Navy stated earlier in the day that the launch might be postponed due to concerns about weather.  However, they pulled off the launch without delays.  The space shuttle Atlantis also landed safely in the morning, another requirement before an attempt could occur.  The Navy only had a 10 second window to strike at the satellite.  A miss would mean that they wouldn't get another shot at the satellite till the next day.

The launch carried a large price tag -- around $60M USD, almost $10M USD for the missile alone.  However, the armed forces say that the costs fall far short of the cost if people suffered from exposure to satellite's fuel.  The satellite carried almost a ton of frozen Hydrazine, which could have created a toxic cloud almost two football fields wide.  While less toxic than some biological and nuclear agents, Hydrazine in gaseous form poses a significant threat.  The Centers for Disease Control and Prevention previously stated that Hydrazine exposure in the short term produces coughing irritated throat and lungs, convulsions, tremors or seizures.  In the long term it can cause liver, kidney and reproductive organ damage.  Its effects are similar to severe ammonia or chlorine exposure.

One group is not very happy about the launch -- the Chinese.  The Chinese took an accusative tone, inferring that the U.S. was simply trying to flex its muscles in a space arms race.  Chinese Foreign Ministry spokesman Liu Jianchao said, "China is continuing to closely follow the possible harm caused by the U.S. action to outer space security and relevant countries.  China further requests that the United States ... promptly provide to the international community the necessary information ... so that relevant countries can take precautions."

China's remarks come as somewhat curious considering it carried out a highly controversial destruction of an aging weather satellite in January of last year.  The Chinese kill was far sloppier than the U.S. effort, as the Chinese hit took place at a higher altitude.  This meant that the debris from the impact remain in orbit and now compose a high percentage of the space junk, endangering shuttles and orbiting satellites.

The U.S. carefully planned the launch, according to Christina Rocca, a U.S. diplomat and expert on disarmament, so that the debris would tumble into the atmosphere and burn up.  She included comments on these plans in the monthly report for the United Nation's Conference on Disarmament.  Further, she said any damage from falling debris would be dealt with graciously.  She said the United States is, "prepared to offer assistance to governments to mitigate the consequences of any satellite debris impacts on their territory."

As a whole the launch is perhaps most interesting as evidence that the U.S. is making large gains in being able to counter nuclear ICBMs, the ultimate goal of SDI.  For an interesting read on the SDI program and its current progress in more depth, please read DailyTech's coverage on the topic.