Weather History: Challenger Disaster 1986

1/27/2012 5:05:40 AM

On Jan. 28, 1986, the Space Shuttle Challenger broke apart 73 seconds into its 10th mission. Cold weather played a strong factor in the disaster.

Today marks the 26th anniversary of the Space Shuttle Challenger disaster, in which the mission's seven crew members were killed after the shuttle broke apart over the Atlantic Ocean 73 seconds into the flight.

According to the Report of the Presidential Commission on the Space Shuttle Challenger Accident, weather conditions were likely one of the factors that contributed to the incident.

STS-51-L was the 25th American Space Shuttle Program flight. It was also the first mission to have a civilian on board, American teacher Sharon Christa McAuliffe.

File picture from January 28, 1986, shows the crew of Space Shuttle Challenger. The space shuttle with seven astronauts on board exploded over Cap Canaveral, Fla. 73 seconds after launch at 16 km height. All occupants were killed. In the front row, from left: Astronauts Mike Smith, Francis R. Scobee, Ronald E. McNair. Back row from left: Ellison S. Onizuka, Christa McAuliffe, Gregory Jarvis and Judy Resnik. (AP Photo/handout)

The Report of the Presidential Commission on the Space Shuttle Challenger Accident said the cause of the loss was a failure of the right Solid Rocket Booster, or SRB. SRBs are positioned to the right and left of the shuttle to help thrust the orbiter into space.

More specifically, a seal designed to prevent gasses from leaking during liftoff failed. This seal is an O-ring made of a type of rubber that is designed to keep a joint in the booster sealed.

Once the seal failed, hot gas began to leak from it, which can be seen in video footage of the launch.

As the shuttle ascended in the atmosphere, it encountered expected high-altitude wind shear conditions that lasted for about 30 seconds of the flight. These wind shear conditions were sensed and countered by the navigation, control and guidance systems.

However, the leak led to an eventual structural failure of the external tank. When the tank failed, the orbiter broke up. Contrary to popular belief, the shuttle did not explode, but rather disintegrated due to aerodynamics.

The commission determined in its findings that a faulty design "unacceptably sensitive to a number of factors" was to blame. These factors included the materials used, physical dimensions, and the temperature conditions.

According to the report, "The weather was forecast to be clear and cold, with temperatures dropping into the low 20s overnight."

Melbourne, Fla., located about 35 miles from Cape Canaveral, recorded a record low temperature of 26 degrees; the normal low on Jan. 28 is 50 degrees.

Likewise, Orlando also had a record low of 26 degrees that morning. Both records still stand, and both locations broke their record lows the following morning as well.

As a result of the cold, gusty winds, ice accumulated on the launch pad area overnight. The ice was removed by crews, and multiple ice checks took place prior to launch.

According to the report, the air temperature at the time of launch, 11:38 a.m. EST, was 36 degrees. This temperature was 15 degrees colder than any previous launch.

A written recommendation existed advising against a launch at temperatures below 53 degrees for fear of O-ring and joint failure, according to the report, but those in charge of making the decision to launch were not aware of it.

The report continues, "If the decision-makers had known all of the facts, it is highly unlikely that they would have decided to launch 51-L on Jan. 28, 1986."

A home video recording of the incident from a backyard in central Florida shows covered bushes, likely done to prevent frost damage.

"That's a historical moment we got on tape, I guess," Jack Moss, who was filming, said just before he turned the camera off.