The rubber rings often worried engineers, especially in cold weather, when they would grow stiff and not mold as well into their grooves. In 1982, after only five shuttle flights, a NASA report said the rubber rings could burn through, destroying the shuttle and everyone in it. In 1983, a U.S. Air Force report gave the seals a 1- in-35 chance of failing. In mid-1984, unusual flames were seen billowing around a booster during a launch of the shuttle Discovery.

The Rockwell group told the [Ronald Reagan] investigators they vetoed a launch under those conditions. NASA executives said they never got that impression, that the Rockwell people had not spoken as bluntly then as they did later under questioning. Still later, tapes of the talks were produced, seeming to support the Rockwell version. But on Jan. 28, NASA officials had overruled the Rockwell protest and decided to launch anyway.

Then Morton Thiokol engineers, afraid the rubber rings would not seal the joints on their rockets in such cold conditions, called NASA to say a launch would not be safe. NASA, the evidence indicates, used what seemed like verbal bludgeoning to get Morton Thiokol managers to change their minds and overrule their own engineers and recommend the launch go on. After those engineers testified about this later before the Reagan commission, three were moved to other jobs.