28, 1986, was flawed because one of the pieces wouldn't hold up in the cold temperatures predicted for that day. He and other scientists explained this to NASA the night before launch, however their objections were disregarded. He then refused to sign off on the required launch recommendation report, even though he knew that his career could be at risk.When he heard that a cold front was coming in on the scheduled launch day, McDonald alerted some of the other engineers to look into how the low temperatures would affect the O-rings which are the circular pieces of rubber that span 12 feet in diameter that seal the metal cylinders of the rocket booster together so that no gases can escape. McDonald knew that in cold temperatures, the rubber hardens and loses its