"It certainly helps put behind us the remaining legal actions resulting from the Challenger tragedy," he said.

Clearly, the Challenger tragedy wasn't enough.

This hiatus is about to end, with the launch of probes that were delayed by the Challenger tragedy.

As an example, in the Challenger tragedy, inquiry began with trying to locate the technology that failed as the reason for the explosion.

Previous news stories have compared similar small rocket failures to major disasters, including the Challenger tragedy.

Nothing, not even the Challenger tragedy in 1986, could change its course and reinvigorate it with a new sense of purpose.

It was the 47th flight in the space shuttle's 11 years of operations and the 22d since the Challenger tragedy.

My job was to stop the Challenger tragedy - I never really had a chance to stop what happened in Dallas.

"One of the valuable lessons learned from the Challenger tragedy was that major space programs cannot be developed 'on the cheap'," he said.

But the new emergency evacuation system, installed after the Challenger tragedy, had yet to be tested.