ORLANDO, Fla. – Central Florida is preparing for its coldest weather in years, but the 1986 late January freeze is one many will never forget.
Not only did temperatures tumble to 22 degrees in Daytona Beach and 26 in Orlando and Melbourne, but it was that same arctic air mass that touched— and forever changed —history along the Space Coast.
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It was the morning of Jan. 28, the day of the space shuttle Challenger disaster.
The right solid rocket booster (SRB) failed during liftoff.
The disaster was caused by an O-ring seal that failed to work properly during the unusually cold conditions. Temperatures behind a strong cold front had dipped to a frigid 26 degrees, well below the average low of 50 degrees.
Preparations were made the night before to prevent or minimize ice formation. Water was drained from pipes on the launch pad, but another factor defeated their efforts. Strong wind gusts blew water on parts of the pad and froze. There was ice on the external tank that housed liquid oxygen and hydrogen.
That morning after seeing ice on the tank, liftoff was delayed to just before lunch time to allow for the sun to melt it. Ice development is considered a debris hazard since it can break off and damage thermal protection tiles on the shuttle. This was an important factor, not just for the external tank but on the pad itself. Ice on the launch pad would have sent astronauts slipping if they had to evacuate due to an emergency prior to launch.
A number of checks were performed on the ice prior to liftoff. Launch time was 11:38 a.m. and temperatures had risen to a chilly 36 degrees. Records later show the temperature near the right SRB that failed was actually closer to 28 degrees due to its height off the ground and the fact that booster was in the shade. The booster on the side getting full sun was 15-20 degrees warmer.
The O-rings used to keep the flammable gas from seeping out of the tank had not been tested in such low temperatures.
Engineers warned of the possible failure of the O-ring given the uncharted territory into such cold temperatures. They feared the putty used to seal the ring could have had ice in or around it, and the hardiness of the ring being a function of temperature could have kept the ring from performing properly in the joint.
Puffs of smoke, less than a second, after liftoff were a sign the seal had failed and the rocket continued to be battered by wind as it changed in speed and direction, known as shear at the different altitudes.
NASA reports showed the wind shear caused the “steering system to be more active than on any previous flight.” All of these elements caused the external tank to fail, leaking the hot gas and resulting in the explosion of Challenger.
Weather played a pivotal role but was not the only factor on that tragic day in history, including the freeze protection plan, other component concerns and administrative influences. In 73 seconds, all seven crew members, including the first civilian to fly, Christa McAuliffe, were gone.
It wasn’t until September 1988 when the United States would return to space flight with five crew members aboard the space shuttle Discovery.