A little more than a year ago, the government launched a reconnaissance satellite from Vandenberg Air Force Base. It turned out to be a dud. The thing never worked. However, it's the size of a bus and it's falling out of orbit and is due to re-enter the Earth's atmosphere in about three weeks.
On board the 5,000 pound satellite is a three-foot round tank of frozen hydrazine gas. The tank and its poisonous contents are expected to survive re-entry. That's why the Pentagon says it wants to blow up the satellite before it comes down on its own.
"In a worst case scenario for the hydrazine, it's similar to chlorine or to ammonia in that when you inhale it, if affects your tissues and your lungs," says Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff.
Gen. Cartwright told reporters it's not likely that debris from the satellite would hit anyone, it's the tank of hydrazine that's the problem. So the Navy is going to launch a missile from an Aegis class guided missile cruiser to try and intercept the satellite just before it hits the Earth's atmosphere.
"We'll use one missile with two backups. We'll have three ships on station," says Gen. Cartwright.
The missile launch is scheduled for sometime next week. Gen. Cartwright said the U.S. is announcing its intentions now to give other nations with space programs fair notice. But a year ago, when the Chinese shot down one of their defunct weather satellites, the United States protested, accusing the Chinese of testing anti-satellite weapons.
Deputy National Security Advisor James Jeffrey says this launch is not a tit for tat.
"Hydrazine equals hazard to human beings and we tried to do what we could to mitigate it," says Jeffrey.
At U.C. Berkeley, Professor Steven Weber heads the Institute for International Studies and is a consultant to the Defense Department and intelligence agencies on the intersection of technology and deterrence.
"The likelihood that any of that gas would actually land in a populated region on the planet is extraordinarily low. That said, if it's a risk we're not willing to take, we should've been talking about this quietly with the Chinese and with other countries as well for months before we made this announcement and surprised people with it," says Prof. Weber.
Professor Weber believes the Chinese will see this shoot down as a unilateral action and will take it in a less friendly way than the U.S. would like them to take it. We have heard no response yet from the Chinese government.