The Challenger Disaster

Back row (L-R): Ellison Onizuka, Christa McAuliffe, Gregory Jarvis, Judith Resnik. Front row (L-R): Michael J. Smith, Francis "Dick" Scobee, Ronald McNair.

STS-51-L Mission insignia

I’m not always that bright. We were playing Trivial Pursuit and someone (not me) got the question: “How many people perished in the Challenger Space Shuttle disaster?”

As my opponent took an interminable period of time to ponder their answer, I couldn’t contain myself. “Holy shit! Come on! I can name all seven!”

Well played. I just gave my opponent the answer and another little wedgie piece for free. Dammit.

Then I did name all seven, from memory: Smith, McNair, Jarvis, Resnik, McAuliffe, Onizuka, and Scobee.

I’ve heard that most people remember exactly where they were when they heard the news about JFK being shot. That was slightly before my time. But I grew up with the NASA quest for the moon. The Mercury missions, then Gemini, then Apollo. And the Space Shuttle program.

For me, Tuesday, January 28, 1986, is my JFK moment. I remember that day vividly. Shortly after sleeping in, I found my roommates in front of the TV. We sat and watched the coverage for hours.

I’ve always been interested in NASA, astronauts and the space program. I have the NASA channel on my Roku and enjoy, much to my wife’s consternation, watching whatever happens to be on, especially if it’s a live feed showing astronauts doing anything in space. I pretty much don’t care what they’re doing. I find it fascinating.

I really enjoyed movies like The Right Stuff, about which Chuck Yeager says, “was a little bit stretched out of shape and Hollywoodized. But I thought the casting was outstanding, and it was fun to watch.” Yeager served as a technical consultant on the film. In his autobiography, Yeager, he says the movie was generally accurate, though. On the back cover of that book, Yeager also says:

The question I’m asked most often and which always annoys me is whether I think I’ve got ‘the right stuff.’ I know that golden trout have the right stuff, and I’ve seen a few gals here and there that I’d bet had it in spades, but those words seem meaningless when used to describe a pilot’s attributes.”

Another movie I love is Apollo 13 which I originally caught during its theater run in 1995. Wow, has the movie really been out that long?

Even before Apollo 11 (the first landing of humans on the moon) in 1969, NASA was already envisioning a space shuttle. By 1972 the Space Shuttle program was formally announced by President Richard Nixon. Due to budgetary and political constraints the version announced by Nixon was less costly and less technically ambitious than the fully reusable design that was originally planned. Nixon’s focus on reducing the cost of space operations essentially transformed the vision of the shuttle program from science and space exploration to one of “payloads.” The focus shifted subtly to the delivery of satellites and military projects into space rather than science and exploration for its own sake.

To get the space shuttle into orbit, more lift was needed. To achieve this, solid rocket boosters (SRBs) were designed. These are the two rockets attached to the sides of the space shuttle’s orange-colored external propellant tank. The SRBs provide 83% of the liftoff thrust required to get the space shuttle into orbit.

The SRBs are 149 feet long and 12 feet in diameter. Before ignition each SRB weighs about 2 million pounds. And the SRB’s are designed to be reusable. Spent SRBs are recovered from the ocean, refurbished, reloaded with propellant, and reused for several missions.

The interesting thing about SRBs is that once activated, they cannot be turned off or even controlled. But they were the chosen solution for the space shuttle because solid rockets can produce much more thrust than liquid fuel rockets. The SRBs for the space shuttle had two O-rings, a primary and a secondary, designed to prevent hot combustion gasses from escaping from the inside of the motor.

There was pressure to launch on time. The vice president, George H. W. Bush, was going to personally attend the launch. When a weather front was predicted and expected to bring rain and cold temperatures, the launch was postponed and Bush altered his travel plans. Ironically, the bad weather never happened and the launch window had “perfect weather conditions,” but the launch didn’t take place so they could wait for the vice president to make new travel plans.

Then there was a second delay caused by a faulty micro switch in the hatch locking mechanism and the problems in removing the hatch handle.

After these problems were sorted out, the weather front was on the move again. Winds were high and record low temperatures were being recorded in Florida. The temperatures for the launch window were expected to be near 20 degrees F. The lowest temperature ever experienced by the O-rings during previous shuttle missions was 59 degrees F.

Ice on the launch tower hours before Challenger launch

The night before launch there was a meeting (held by teleconference) between engineers and management from Kennedy Flight Center, Marshall Flight Center in Alabama, and Morton-Thiokal in Utah (makers of the SRBs). The recommendation was made to delay the launch until the temperature reached 53 degrees F. However, there was no data on O-ring performance in temperatures lower than 59 degrees F, so it couldn’t be proven that lower temperatures would be unsafe. The final result of this teleconference was that while cold was still a safety concern, the danger was “inconclusive” and launch was “recommended.” Some engineers refused to sign that recommendation.

As we all know, the shuttle did launch, the O-rings did fail, in fact, problems were later detectable after ignition even before Challenger had cleared the launch pad. Then, 73 seconds into flight, the vehicle exploded.

The temperature at ground level at Pad 39B was 36 degrees F, which was 15 degrees F cooler than any other previous launch by NASA.

Since then, we know that the crew was aware something had gone wrong. Experts, including veteran astronauts, concluded that a sheet of flame swept up past the window of pilot Mike Smith, and that there was no question that Smith knew of the disaster. The cabin crew recorder captured his last words.

“Uh oh!”

Evidence exists that suggests the crew was alive following the explosion.

Following the Challenger disaster, examination of the recovered vehicle cockpit revealed that three of the crew Personal Egress Air Packs were activated: those of Resnik, mission specialist Ellison Onizuka, and pilot Michael J. Smith. The location of Smith’s activation switch, on the back side of his seat, means that either Resnik or Onizuka could have activated it for him. This is the only evidence available from the disaster that shows Onizuka and Resnik were alive after the cockpit separated from the vehicle.

The explosion occurred at 48,000 ft. above the Atlantic Ocean. Momentum carried the crew compartment to a peak altitude of 65,000 ft. The crew compartment is believed to have remained intact following the explosion.

One solid booster broke free, its huge flame a cutting torch across Challenger, separating a wing. Enormous G-loads snapped free the other wing. Challenger came apart — but the crew cabin remained essentially intact, able to sustain its occupants.

The crew cabin, reinforced aluminum, stayed solid, riding its own velocity in a great curving ballistic arc, reached the top of its curve, and then began the dive toward the ocean.

It was only when the compartment smashed, like a speeding bullet, into the sea’s surface, drilling a hollow from the surface down to the ocean floor, that it crumpled into a tangled mass.

It is estimated that it took the crew compartment 2 minutes and 45 seconds to impact with the ocean. The impact was at 207 mph or a “declaration of impact” of over 200 g, far beyond human survivability levels.

It is believed that the crew survived the explosion but could not remain conscious at altitude. The air packs would not have been sufficient to prevent unconsciousness. But the crew may have remained alive until the moment of impact with the ocean.

A NASA report said:

The forces on the Orbiter (shuttle) at breakup were probably too low to cause death or serious injury to the crew but were sufficient to separate the crew compartment from the forward fuselage, cargo bay, nose cone, and forward reaction control compartment. … The cause of death of the Challenger astronauts cannot be positively determined.”

I first heard this stunning revelation while recently watching When We Left Earth, an excellent six-part series that chronicles NASA from Mercury, Gemini and Apollo through Skylab, the Shuttle Program, Hubble and the International Space Station.

Christa McAuliffe undergoing pre-flight training experiences weightlessness during a KC-135 "vomit comet" flight

Sources used for this post:
MSNBC: An Eternity of Descent
ENGINEERING ETHICS: The Space Shuttle Challenger Disaster
Wikipedia: Space Shuttle Challenger disaster
Wikipedia: Space Shuttle Solid Rocket Booster
Wikipedia: Judith Resnik
Wikipedia: STS-51-L
Wikipedia: Space Shuttle Challenger
Wikipedia: Christa McAuliffe