I wasn't recommending not launching because of what I knew, but because of what I didn't know, and I thought that NASA was in the same position. It just wasn't worth taking the risk with all of these unknowns.

It was the first time in my two-year career in the Shuttle program that we were experiencing a last-minute crisis of this magnitude just before a launch.

fly. This was the first time that NASA personnel ever challenged a recommendation that was made that said it was unsafe to fly. The flight readiness review process was always structured around the contractors having to prove beyond a shadow of a doubt that their hardware was safe to fly.

Sitting down, Commissioner Feynman commented that he held us both in high regard and that we were kind of like him in a way, a sort of maverick willing to “say it like it is.” Such a statement coming from a former Nobel Prize winner in physics, who was held in very high esteem by his students and peers, was a high compliment, indeed. Feynman then

was now evident that the joint failure had been initiated at ignition by a failure of the O-rings to seal off in the aft right-hand solid rocket booster field-joint.

Ignition always makes me nervous, but this time I was far more concerned because of the effects that the extremely cold temperatures could have on the sealing capability of the O-rings in the SRB field-joints. I breathed a sigh of relief as Challenger lifted off the pad. I really believed that if the O-rings were to fail, it would be at ignition

NASA knew that I did not feel at all good about the change from our original recommendation not to launch. My concern focused on the effects of cold temperature on the performance of our O-rings, the rubber seals that our company's engineers had designed at the beginning of the Shuttle program to prevent hot gases from leaking through the joints

Roger Boisjoly stood fast, saying he believed the data indicated that the cold temperatures were going away from the direction of goodness.

Dear Dr. Fletcher: We are greatly disturbed by testimony of May 2 to the Rogers Commission that strongly suggests that Morton Thiokol, Inc., and at least one NASA official, have attempted to control the flow of information to the Commission through acts of intimidation and punishment. In evaluating that testimony, it appears that a Morton Thiokol