Nasa plans first launch since 'Columbia' disaster

Nasa administrator Michael Griffin yesterday said he and his staff were as ready as they were ever going to be to relaunch the shuttle following an exhaustive review of what went wrong with the Columbia flight and an effort to plug as many of the security holes as possible.

"We're currently 'go' for launch of Discovery on July 13," Mr Griffin said. "The proximate causes of the loss of Columbia have been addressed. Many other things which could have been of concern or would have been of concern have also been addressed. We honestly believe this is the cleanest flight we have ever done. The only other flight that will ever be cleaner is the next one."

It has been a fraught couple of years for Nasa, which has had to put construction of the International Space Station, which the shuttles were servicing, largely on hold while it investigated the Columbia disaster. The new shuttle was originally scheduled to be launched in May, but that was postponed when some last-minute problems concerning the possibility of ice damage were discovered.

Earlier this week, an independent panel found that Nasa had not fully implemented three of the 15 safety recommendations made after Columbia. But the panel said the oversights were not serious enough to warrant postponement.

"We are being as smart about this as we know how to be," Mr Griffin said. "But we are up against the limits of our human knowledge. If someone wants more, they're going to have to find smarter humans."

Columbia came to grief because a suitcase-sized piece of foam hit one of its wings during take-off, punching a hole in the skin of the craft that allowed hot gas to seep in and trigger an explosion on re-entry into the earth's atmosphere. Discovery, the new craft, is still susceptible to foam damage, according to the independent panel, but the risk of it creating a major problem is now much diminished.