NASA will fly each space shuttle mission only when it’s ready to fly safely, an approach that dovetails with a pending congressional plan saying the space shuttle fleet doesn’t necessarily have to complete all scheduled missions by a Sept. 30, 2010, deadline.

The space agency will “do each mission” individually, with full concern that no safety problems loom, Bill Gerstenmaier, associate NASA administrator for space operations, said in a news briefing Saturday evening. “We’re not going to do anything dumb” and fly when there is a high risk of an accident, he said. “When we’re ready to fly, we’ll go fly.”

Officially, NASA has only eight space shuttle missions to fly this year and next. But a ninth mission may be added, where a shuttle would take a $1.5 billion experiment, the Alpha Magnetic Spectrometer, or AMS, to the International Space Station. Otherwise, the AMS will sit uselessly on the ground, the money wasted.

Members of Congress are moving to ensure that the extra shuttle mission is funded.

“We’ll see what we get in the budget,” Gerstenmaier said, and “see how things come out.”

NASA is prepared to fly that extra mission next year if Congress funds it, he said.

How long the space station then would remain in operation is unknown. Current law authorizes the station to be manned only through 2015, but Gerstenmaier said it may fly until 2020 or 2025.

On another issue, he expects a problem with an external cargo platform that frustrated astronauts on the just-ended Space Shuttle Discovery mission to the station to be solved by spacewalkers on some later mission.

While Gerstenmaier and other top NASA officials exulted in Discovery completing the major construction work on the space station, installing a huge pair of solar array wings, and expect Congress to extend the life of the space station, he was asked how NASA will handle destruction of the space station when Congress decides to end its life.

Gerstenmaier said probably an unmanned, disposable European Automated Transfer Vehicle, or ATV, will be sent to dock with the station. Then the ATV will use thrusters to shove the space station out of orbit and back into the atmosphere, where much of its 900,000 to 1 million pounds of mass will burn up. Any remaining fragments will fall into the Pacific Ocean.