A senior U.S. military officer says there is a high degree of confidence that the warhead from a missile fired by a U.S. Navy ship west of Hawaii late Wednesday hit the fuel tank of a failed American satellite, eliminating any significant danger from the satellite's fall to earth. VOA's Al Pessin reports from the Pentagon.
The number-two U.S. military officer, General James Cartwright, showed a video of the impact, and said analysts believe the warhead, which has no explosive charge of its own, not only destroyed the satellite, but hit the exact spot where the tank of dangerous hydrazine fuel was located.
"We have a fireball, and given that there is no fuel, that would indicate that that is a hydrazine fire," he explained. "We have a vapor cloud that formed. That, again, would be likely to be the hydrazine. We also have some spectral analysis from airborne platforms that indicate the presence of hydrazine after the intercept."
But General Cartwright said experts need to do more analysis to be absolutely sure the tank was destroyed and the fuel burned up. He says U.S. military and civilian space radars are tracking the debris from the impact, and that some pieces have already entered the earth's atmosphere and burned up.
"It generally takes us about a day to two days to get a good sense of each piece of material that is up there," he added. "Thus far, we have seen nothing larger than a football."
The general says that, and the path of the debris' orbit, mainly over water, means there is now little danger to people on the ground, but he says military units remain on alert to help in case any small pieces of the satellite do hit populated areas. The main concern was the hydrazine fuel, which can cause respiratory problems and even cancer.
The failed satellite, believed to have had an intelligence mission, was launched 14 months ago and stopped responding to commands almost immediately. Since then, it has been in a deteriorating orbit, and it would have re-entered the atmosphere on its own in the coming weeks.
Some countries, particularly China, have criticized the U.S. decision to shoot down the satellite, saying the operation was a thinly-veiled test of a new anti-satellite weapon system. U.S. officials have consistently denied that, and speaking in Hawaii Thursday Defense Secretary Robert Gates offered to provide China some additional information about the shoot-down.
"Our whole approach to this was one of compete transparency, prior notifications, and letting everybody know what was going on and the purpose of the activity," he said. "And we certainly are prepared to share whatever, appropriately, we can."
At the Pentagon news conference earlier, General Cartwright General Cartwright said the State Department is keeping other nations informed of the path of the debris, but he said no country has been notified that it is at particular risk.
The general says the missile, and two others that were standing by, had special modifications, what he calls "mods," and will be returned to regular service as part of the new system designed to defend the United States from a ballistic missile attack.
"This is a one-time mod," he noted. "If you put this mod in we cannot use the ship or the missile for another function without taking the mods out, so it is not something that we would be entering into the service in some standard way. This is a one-time type of event."
General Cartwright and other experts say this was a particularly difficult technological challenge, because both the missile and the guidance software had to be modified, and because the satellite was somewhat higher and moving much faster than the incoming missiles the system was designed to intercept. Officials have described the missile defense system as trying to use a bullet to hit a bullet. The general said the warhead and the satellite hit each other at a combined closing speed of 35,000 kilometers per hour, about 250 kilometers above the earth.
General Cartwright, who is the Vice Chairman of the Joint Chiefs of Staff, says Defense Secretary Robert Gates approved the missile launch about eight hours before it happened. He said bad weather in the area where the Navy task force was operating cleared in time for the very narrow launch window of less than a minute. Officials had said they would not launch the missile unless conditions were nearly perfect and the chances of success very high.
The general reports those involved in the project reacted when sensors indicated they had succeeded.
"You can imagine at the point of intercept last night, there were a few cheers from people who have spent many days working on this project," he added.
But the general says analysts will continue to work on the data for another day or two to be sure the fuel tank was destroyed, and will continue to monitor the debris to ensure no large pieces hit populated areas, and to respond with help if they do.