By Bettina H. Chavanne

NASA, DOD and the White House defended their plans for a ballistic-missile take-down of a falling National Reconnaissance Organization (NRO) satellite, speaking to reporters this afternoon and planning to address international organizations in a "diplomatic global roll-out" later in the day.

Aviation Week first reported the shoot-down plans Tuesday on its AviationWeek.com and Aviation Week Intelligence Network websites.

Satellites have de-orbited before, but never with this much associated risk, said U.S. Marine Corps General James Cartwright, vice chairman of the Joint Chiefs of Staff. "It's the hydrazine that's the distinguishing characteristic," Cartwright said in a Pentagon briefing. "Our objective was whether we could reduce the risk to space, airborne or terrestrial platforms."

A Standard Missile 3 (SM-3) will be launched from one of three Aegis ships on station during a window of opportunity between late February and early March, with two SM-3s as back-ups. "It'll be one shot... If we're not successful we'll reassess," Cartwright said. He added only that the ships would be positioned in the Northern Hemisphere and the Pacific.

Accusations that the only reason for the shoot-down is that the satellite contains classified information were rebuffed. "This is not an issue," Cartwright said. "Our assessment [of the satellite] is that it wouldn't be of high intel value... the hydrazine is the only reason we're taking extraordinary measures."

The space shuttle Atlantis is still in orbit, and the satellite shoot-down will not occur until the shuttle has returned to Earth. The International Space Station is not at risk from the missile launch, said NASA Administrator Michael Griffin at the briefing. "We looked very carefully at the increased risk to the shuttle and the space station," he said. "Broadly speaking, they are negligible." If the shot is successful, Griffin added, there is no anticipated risk from debris to the upcoming STS-123 International Space Station assembly mission set for a March 11 launch.

The SM-3 will be re-configured to perform this mission on a one-time basis, said James Jeffrey, White House Deputy National Security Advisor. Although the likelihood of the hydrazine tank landing in a populated area is relatively small, "it was enough of a risk for the President to be concerned," said Jeffrey.

SM-3 missile photo: U.S. Defense Department