JACKSONVILLE, Fla: -

Monday marked the 27th anniversary of the Space Shuttle Challenger Explosion that killed 7 astronauts some 73 seconds after takeoff. Above is a chilling image taken by NOAA satellites moments after the explosion on January 28th, 1986.

According to the presidential commission on the Space Shuttle Challenger disaster, temperature was widely believed to have played a pivotal role in the accident. The forecast the night before the launch called for clear and very cold conditions with overnight lows in the low 20s. In fact, both Melbourne and Orlando both recorded a low of 26 degrees that morning; both of which were records. The temperature at the time of launch (11:38 AM est) was 36 degrees fahrenheit; some 15 degrees colder than the next coldest launch observed.

The O-Ring issues in regards to cold temperatures were not a surprise to the investigation into the breakup of STS-51-L (Challenger). In fact, puffs of smoke (as seen in the STS-51-L's launch) had been observed before. Here's an excerpt from the presidential commission:

"Of 21 launches with ambient temperatures of 61 degrees Fahrenheit or greater, only four showed signs of O-ring thermal distress; i.e.,erosion or blow-by and soot. Each of the launches below 61 degrees Fahrenheit resulted in one or more O-rings showing signs of thermal distress."

At the time of launch, the O-rings facing the sun had an ambient temperature exceeding 50 degrees while the O-rings on the right side of the shuttle facing away from the sun were still well below freezing allowing them to easily fail upon liftoff. 

While NASA's biggest fear for launches is lightning, there are many other factors to be considered when preparing a launch such as: lightning, upper-level winds and obviously temperature. It just goes to show that every aspect of weather can be deadly---either directly or indirectly---regardless of whether how tame or insignificant a clear sky and a freezing temperature can be.

(Source: The Presidential Commission on the Space Shuttle Challenger Accident Report, June 6, 1986 p.40, p.70-81)