NASA will go ahead with the launch of Discovery after fixing slight damage to heat-resistant tiles caused by a fallen window cover, a NASA spokesman said Tuesday.

"The issue has been resolved. Launch is a go," NASA spokesman Mike Rein said.

The plastic and foam cover, used to keep windows clean until the launch, fell off the shuttle and damaged thermal tiles near the tail. This came just hours after NASA Administrator Michael Griffin said that NASA has done everything it can to ensure the safety of the first shuttle flight since the 2003 Columbia disaster.

"We've done everything we need to do" for the safety of shuttle flight, and "we are in good shape," he told a news conference after a meeting of NASA officials, one day before Discovery's liftoff, which is scheduled for 3:51 PM EDT (19:51 GMT) Wednesday.

He said his message to millions of people worldwide to watch the event from TV is that "We've come through a very difficult period in NASA. ......Now we're back on line and ready to go."
The flight of Discovery is "crucial" for NASA, the US nation, and the US space exploration program, he said.

While acknowledging the US space agency has not yet developed reliable technology for orbit repairs as required by the investigation board of Columbia accident, and the safety improvements NASA had made has yet to be tested in the flight of Discovery, Griffin noted that NASA has been asking questions and answering them appropriately.

The task force reviewing NASA's return-to-flight preparations had concluded that despite the progress in many aspects, NASA has failed to meet three of the 15 recommendations raised by the Columbia accident investigation board. It said NASA has not eliminated the debris risk, failed to sufficiently toughen up the shuttle's shell, and remained incapable of orbit repairs.

The Columbia tragedy in Feb. 2003, in which all seven astronauts aboard were killed, was blamed on a suitcase-sized insulation foam that fell off the external fuel tank on liftoff and harmed Columbia's left wing, leading to the shuttle's disintegration during re-entry.

This had led to many major modifications in the fuel tank design. But NASA technicians had later found from a tanking test in last April that ice can form on the tank when it is filled with super cold liquid oxygen and hydrogen fuel, and that any ice breaking off the tank on liftoff could do bigger harm if it smacked into the shuttle. Safety concerns had delayed the launch from mid May to July.

After its own review of the return-to-flight preparations, NASA decided that the level of risk from debris falling off the external fuel tank and harming the shuttle is acceptable.

At the news conference Tuesday, Griffin said it was not a difficult decision for him to make to approve the resumption of flight for NASA's shuttle fleet, which has been grounded since the loss of Columbia.

The NASA chief told reporters he has been in contact with families of crew members killed in the Columbia disaster by phone, face-to-face or by emails, adding that he is "very pleased" that they are supportive of NASA's return-to-flight effort.

These families issued a joint statement Tuesday to express their support for NASA's work.

"As NASA prepares to launch the Shuttle Discovery, we, the Columbia Families, would like to show our support for the STS-114 crew and all the dedication and talent of those who supported this return to flight effort."

"As important as solving the technical risk is, we must be vigilant to ensure the organizational and cultural issues that contributed to Apollo, Challenger, and Columbia are forever remembered," the statement noted.

(Xinhua News Agency July 13, 2005)