How weather doomed a space shuttle, and why it wasn’t just the cold

An unseasonably frigid air mass settled over the Southeastern U.S. 30-years ago Thursday, dropping temperatures at Cape Canaveral to 24 degrees at 7 a.m.

The Space Shuttle Challenger, with teacher Christa McCauliffe, was being readied on its launch pad for what was to be a landmark liftoff watched in classrooms, offices and homes nationwide.

The space shuttle Challenger exploded 73 seconds into liftoff on Jan. 28, 1986, killing all seven aboard. (Florida Photographic Archives)

The space shuttle Challenger exploded 73 seconds into liftoff on Jan. 28, 1986, killing all seven aboard. (Florida Photographic Archives)

But Mother Nature, without intent, malice or remorse, would doom the fateful mission.

Within 74 seconds of takeoff, Challenger exploded in a fireball, debris falling from the sky like tears.

Yes, it was cold.

Debate swirled about the ability of the rubber O-rings that sealed joints of the solid-rocket boosters to stand up to temperatures that were just 36 degrees at liftoff. There was evidence the seals weren’t up to the job as gray smoke leaked through an O-ring on the right solid-rocket booster near the time of takeoff, according to the Report of the Presidential Commission on the accident and Penn State’s Department of Meteorology, which dedicate a portion of a lesson to the tragedy. (Full disclosure. I’m taking classes with the department to better understand the weather I write about.)

But research from both the Report of the Presidential Commission on the Space Shuttle Challenger Accident and Aersopaceweb.org, a non-profit run by aerospace scientists and engineers, said an O-ring leak likely resealed itself after liftoff.

“It is very possible this seal could have been maintained indefinitely if not for the fourth and final factor that doomed the mission,” notes Aersopaceweb.org.

That factor was vertical wind shear – a condition produced by a change in wind velocity with speed and/or direction with height.

At about 37 seconds into the flight, wind shear began to tear at the shuttle. It lasted just 27 seconds, but the force of the gales increased to 144 mph as the shuttle soared higher into the atmosphere.

While navigational systems compensated for the strong shear, the winds, described as the “worst wind shear in the history of the Shuttle program,” forced the rocket booster to flex. The flex dislodged the aluminum oxide plug that had sealed the damaged O-Rings, according to Aersopaceweb.org.

A small flickering flame appeared at about 58 seconds into flight. The Challenger was gone 15 seconds later.

 

 

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