On January 28, 1986, the 25th flight of NASA's space shuttle program launched from Kennedy Space Center. The Space Shuttle Challenger was set to begin a planned mission of six days and 34 minutes. At 11:38 a.m., the temperature at Cape Canaveral was 36 degrees Fahrenheit. The launch was originally scheduled for January 22 and had been re-scheduled several times for many different reasons, one of which was "unacceptable weather." The launch of the space shuttle went as planned. However, 0.678 seconds after lift off, a strong puff of gray smoke was seen spurting from the area of the right solid rocket booster. Beginning at about 72 seconds after the launch, a series of tragic events that occurred very quickly ended the flight. The shuttle had climbed to an altitude of 46,000 feet and was traveling at Mach 1.92 when it was completely engulfed in flames. Tragically, the explosion claimed the vehicle as well as the lives of the seven crew members.
This accident began several investigations centered around the cause of the explosion. In the Report of the Presidential Commission on the Space Shuttle Challenger Accident, the findings indicate the cause of the accident, and recommendations are specified to avoid a similar event in the future. The indicated reason for the accident was O-ring failure in the right solid rocket booster. Cold weather was also determined to be a contributing factor. Among the most interesting studies, was the study of the function of .
O-rings when under extreme thermal conditions. Apparently, when an O-ring is exposed to cold temperatures, it does not react in the usual manner. It was found that the resiliency of an O-ring is directly related to its temperature. As noted above, the temperature at the time of launch was 36 degrees Fahrenheit, which was 15 degrees lower than the next coldest previous launch. The temperature at the site of the suspected O-ring failure was determined to be 30 degrees, while the temperature on the opposite side (the side facing the sun) was 50 degrees.
