Shuttle to race home out of Navy's field of fire

— -- Space shuttle Atlantis departs the International Space Station Monday to return to Earth as quickly as possible, to maximize the amount of time the Pentagon has to shoot down a dying spy satellite.

The shuttle must be safely on the ground before a Navy ship fires a missile at the satellite, which is slowly falling out of the sky with its load of toxic fuel. The shootdown is intended to shatter the satellite's fuel tank into fragments, allowing the fuel to dissipate.

If the fuel tank isn't blown up, it will plunge to Earth and spew a cloud of fumes that could injure or kill anyone nearby, said Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff.

Cartwright and other officials estimated they have a seven- to eight-day window to bring down the satellite before it would make a final, uncontrolled dive to the Earth's surface in early March. To give the military more flexibility, NASA will take the rare step of opening two runways Wednesday, the day Atlantis is scheduled to come home: the shuttle's normal runway in Florida and a backup landing strip in California.

The shuttle usually doesn't touch down in California unless Florida has bad weather for two consecutive landing days. Landing in California costs an extra $1 million, in part to ferry the shuttle back to its Florida hangar.

In preparation for their homecoming, the Atlantis crew closed the door between the shuttle and the station Sunday. The shuttle launched Feb. 7 on a mission to expand the station by adding a European laboratory.

Among the astronauts aboard Atlantis was Daniel Tani, who has lived for the past four months on the orbiting lab. During Tani's stay in space, his 90-year-old mother was killed when a train hit her car in December, making Tani the first astronaut in orbit to lose a close relative. Tani's mother raised him after his father died when he was a young boy.

During a farewell ceremony Sunday, Tani said he had been thinking about "my mother, my inspiration." Another subject on his mind, he said as he choked up, was his wife, "the love of my life," prompting station commander Peggy Whitson to wipe away tears.