NASA Says Shuttle "Ready to Fly"

June 8, 2006 -- -- Touting design changes and improvements -- such as a redesigned fuel tank and new sensors and windows -- NASA said today that Space Shuttle Discovery has been cleared to fly.

The agency warned, however, that there are still engineering questions to resolve and cautioned about the risks inherent in space flight.

"We are ready to go into what I think will be a rapid succession of flights in the next few months," said space shuttle program manager Wayne Hale.

The next shuttle flight is scheduled to launch in a window that opens July 1 and closes July 19.

In a series of press briefings today at the Johnson Space Center in Houston, NASA managers talked about the changes to the shuttle and noted that the next flight would test what Hale called "the largest aerodynamic change to this vehicle that has been made since we started flying 25 years ago."

That change involves foam structures on the large orange external fuel tank that on previous flights acted as windshields, protecting the cables and pressurized fuel lines that run along the outside of the tank.

Hale said that the foam windshields were added to the shuttle design shortly before the first flight in 1981 because engineers weren't sure at the time whether the external components could withstand the tremendous force and turbulence of a launch.

In 2003, a chunk of foam insulation fell off Columbia's fuel tank during launch, hit the ship's wing, and critically damaged its heat shield. Seven astronauts aboard the shuttle died when Columbia broke apart as it flew through the atmosphere for landing.

Large foam chunks also fell off during Discovery's liftoff last year but did not strike the orbiter.

Hale said today that unlike in 1981, engineers have now improved wind tunnel technology and provided better aerodynamic modeling that helped NASA conclude that the shuttle could fly without the foam windshields.

"We certainly believe we have sufficient engineering evidence to show that we will not lose large pieces of foam off the tank the next time we fly," he said.