The U.S. will shoot down a damaged spy satellite expected to hit Earth in early March, officials said at a news conference Thursday.

Gen. James Cartwright, Joint Chiefs of Staff vice-chairman, speaks to the media on Thursday.
(CBC)

The satellite, launched in December 2006 and weighing more than 2,000 kilograms, lost power almost immediately and never reached its final orbit.

President George W. Bush, acting on advice of security officials, has decided to try to shoot down the satellite before it enters Earth's atmosphere.

Officials said a missile would be fired from a U.S. navy cruiser off Hawaii next week at the earliest.

The officials said downing the satellite would help ensure it landed in an unpopulated area and help destroy the satellite's thruster tanks. The tanks contain a toxic rocket fuel called hydrazine, which can harm anyone who comes in contact with it, causing a burning sensation similar to chlorine.

Deputy national security adviser James Jeffrey said that if the satellite impacted on land, the hydrazine could spread to an area as large as two football fields.

"The likelihood of it falling in a populated area is small. But there was enough of a risk that the president asked us to review our options," said Jeffrey.

In addition to safety concerns, U.S. officials told the Associated Press earlier that they do not want the satellite to fall into the wrong hands, as it carries a sophisticated and secret imaging sensor.

China drew criticism

But Joint Chiefs of Staff vice-chairman Gen. James Cartwright denied that, saying classified technology is not an issue because the heating that would occur on re-entry would destroy any technology and "would not justify using a missile to shoot it down."

NASA administrator Michael Griffin said the risks to the International Space Station and space shuttle Atlantis were negligible.

It will be the first time the U.S. has ever attempted to shoot a spacecraft down with a surface-to-air missile, Cartwright said.

Last year, China drew criticism from a host of countries, including the U.S., after it used a missile to shoot down an old weather satellite about 865 kilometres above the Earth. The move was widely viewed as one that could lead to the increasing militarization of space.

Cartwright said this case is different because the U.S. is notifying countries and international organizations before attempting to knock out the satellite. He also said the plan to shoot it down as it enters the atmosphere will reduce the potential for debris to remain in orbit.

With files from the Associated Press