Grounded a Year, Shuttle Discovery to Launch in July

After completing the biggest overhaul of the space shuttle’s design since it started flying 25 years ago, NASA said Thursday that Discovery is now ready for a July 1 launch to the International Space Station.

“It’s been a long road for us, but indications are the vehicle is in good shape,” said Steve Lindsey, the commander of the seven-person crew. “I’m very optimistic about meeting the July launch window.”

Since the last shuttle flight, last summer, engineers have replaced 5,000 spacers between heat-resistant tiles under the nose of Discovery, changed 242 tiles and replaced 44 insulating blankets around the cockpit.

The biggest change was removing 34 pounds of foam insulation from around cables on the outside of the giant external fuel tank that the craft rides piggyback into orbit.

Engineers worried that exposing the underlying cables to the heavy air pressures of launch might interfere with the shuttle’s flight-worthiness. But NASA said wind tunnel tests showed there was a good margin of safety, even without the foam ramps.

“We found no showstoppers,” said John Chapman, manager of the external tank program, at a series of news briefings at Johnson Space Center in Houston. “The overwhelming opinion is, we are ready to go.”

The changes are designed to prevent a repeat of mishaps that plagued the last flight, chiefly the flaking off of a 1-pound piece of foam during launch. The foam did not hit Discovery, which landed safely after a two-week mission.

But the incident was considered serious given that a falling piece of foam had damaged the shuttle Columbia in 2003, leading to its destruction on reentry and the death of its crew.

N. Wayne Hale Jr., head of the space shuttle program, warned that despite the new modifications, foam would still come off the tank, but that the biggest piece should be no larger than 0.2 pounds.

Some NASA engineers aren’t so sure.

They are concerned about the ice frost ramps on the fuel tank, which are made up of 34 chunks of foam.

After a spirited internal debate, top managers decided to leave the ice frost ramps alone until they see how the current modifications work.

The shuttle is scheduled to deliver food and water to the space station, along with a freezer, and an oxygen generation system that will allow the station to house six crew members.

NASA Administrator Michael D. Griffin has estimated 16 more flights will be necessary to finish construction of the space station. Presuming no problems surface on the July launch, NASA plans to try for a second shuttle launch Aug. 28.