As they took temperature readings around the shuttle with a handheld infrared thermometer, the instrument produced odd results: the surface of the left-hand solid rocket booster registered at around 25 degrees Fahrenheit, close to the air temperature at sunrise. But at the bottom of the right-hand booster, near the aft field joint, the reading was just 8 degrees—an astonishing 24 degrees below freezing; that just couldn’t be right. Stevenson and his engineers assumed the thermometer was malfunctioning, and took note of the numbers, but kept the data to themselves.
