30 Years Ago - Challenger STS-51L

[mekender]

Forgive my lengthy wordsmithing...

It is hard to believe it was 30 years ago today... Probably the first major news event I can remember, I was standing on the playground in kindergarten watching as it cleared the trees and soared off into the blue sky. I had watched such an event more than a dozen times before in my young life and was excited every time... What I saw that day, I could not understand at the time but I still can see it in my memories as clearly as if it was playing out in front of me today.

In the years since, it has been a fascinating subject for me to study, reflect on and learn about...

The shuttle did not "explode" as so many people will commonly say in conversation, rather it was torn apart due to massive aerodynamic stresses during what the USAF likes to call "loss of controlled flight"... Essentially it was moving so fast that when it turned too far from the direction it was moving, the structure failed and it broke apart.

72.2 seconds into the flight, the right solid rocket booster ripped apart from its bracing to the liquid fuel tank causing a rather sharp change in the direction of the vehicle ... Slightly more than 9/10ths of a second later, structural failure of both the liquid oxygen and liquid hydrogen tanks occurred with the liquid hydrogen tank smashing into the liquid oxygen tank. Roughly 40 milliseconds later, the solid rocket booster impacted the fuel tank which was already disintegrating. As the liquid fuel dispersed into the air, it ignited creating a massive fireball that did envelop the whole assembly but by every bit of evidence, the Shuttle escaped this fireball as it continued upward.

At this point, the vehicle was moving at about Mach 1.92, almost 2 times the speed of sound, roughly 1,473 miles per hour at an altitude of 46,000 feet. The Space Shuttle itself still had structural integrity and thus would have been accelerating upward due to the launch at a faster rate than the no-longer aerodynamic fuel tank. At approximately 73.2 seconds into the flight, a bright flash was observed in the area between the fuel tank and the Shuttle, this is most likely the moment when the Shuttle started to separate from the fuel tank. Roughly 400 milliseconds later, the Shuttle itself started to break apart. In that time, the orbiter would have traveled more than 850 feet upward (roughly 7 times its own length) while the fuel tank was disintegrating behind it.

The orbiter was already doomed though, as the disintegration was occurring, the vehicle was hit with a severe jolt. With the 3 engines on the orbiter going at full thrust and the very rapid loss of several thousand tons of weight being ripped from the belly of the craft, it was suddenly exposed to a force of around 20g, four times the structural capability of the craft. The nose of the craft pitched downward and the entire front section was ripped off. When that happened, the payload bay was exposed to an almost instant rush of air moving at 2 times the speed of sound. The resulting pressure ripped the craft to pieces. The wings broke free and one can be seen tumbling out of the debris cloud on video. The entire tail section with the three engines attached and still burning can also be seen tumbling free.

The boosters survived mostly intact because of how robustly they were built and due to the sudden loss of weight they were attached to, they hurtled clear of the debris cloud. The ground controller issued a self destruct command to them at roughly 110 seconds into the flight.

The front section of the craft can be seen on the various videos captured of the event exiting the debris cloud at roughly 75.25 seconds into the flight. It continued upward and eventually reached an altitude of 65,000 feet some 25 seconds after the breakup of the vehicle.

Most incredibly, it is widely believed that some, if not all, of the crew not only survived the initial breakup of the vehicle, but were at least conscious for some part afterwards. The crew cabin was very strongly designed and the estimated g-forces on the cabin were not enough to seriously damage it or to cause serious injuries to the crew. It is not known if the cabin remained pressurized though so it is possible that any of them being conscious would have been a brief thing. They do know that several personal air packs were activated within the cabin and several switches on the right side of the pilot's panel were moved. These switches are spring loaded and have to be pulled outward before being turned so they know that this was done by a human hand. But by that point, there was nothing to be done... 3 minutes and 58 seconds after launch, the cabin hit the ocean at around 200mph subjecting the cabin to an estimated force of 200g which completely destroyed it.

The thing that I get most awestruck about the early days of the Shuttle Program is that every single person that strapped themselves into those seats knew full well that major failures during the first 350 seconds after launch were considered unsurvivable events... There were no options to abort that meant the craft or crew could survive. There were no ways to bail out of the craft. Ditching into the ocean would be fatal... And yet they did it anyways.

Ronald Reagan's speech that night is probably one of the most emotional ones I have ever seen a president give:

https://youtu.be/gEjXjfxoNXM

[JustinR]

Space flight is perhaps the least error-tolerant human endeavour. The fact that we haven't lost more astronauts is a testament to the extraordinary people involved, from the engineers to the maintainers to the managers to the astronauts themselves. That doesn't make their loss any easier to bear, nor their deaths any less of a tragedy. May they rest in peace.

ITEM-325038-NASA-2.jpg

[mekender]

I feel very fortunate to have seen somewhere above 75% of the Shuttle launches with my naked eyes... The closest I have ever been to one was during the first night launch, I was in the back of my family's station wagon at the press site for that one and man it was LOUD... Other fabulous viewing areas were my Uncle's dock, 3 canals inland from Coconuts on the Beach in Cocoa Beach, From the Cocoa Beach Pier and from the jetty at Port Canaveral...

Though I will say my parent's front yard was a damn good place too. Our street went almost due East-West and from my front yard to the end going east was a good 750' or so... If you stood out on the curb, you could see the launch break above the trees at about 15 degrees to the right of the center of the street. Similarly you had almost as good of a view from my back yard until the last 10 years or so when the neighbors trees got really tall. I remember several times seeing one launch while swimming in the pool and being able to feel the vibration in the water before you could hear it in the air. Even some 50 miles from the launch pad, on a humid enough day you can actually hear the low rumble of that sucker heading for orbit.

[Cobar]

I was eating lunch out of my Challenger lunch box in the school cafeteria when it happened. When we went back to class the teacher told us and we spent the rest of the afternoon watching the news.

[Mike OTDP]

I only saw one launch, STS-104, in person. Night launch...one of the greatest spectacles known to man.

When the Challenger mishap happened, I was out getting lunch. Heard on the radio. Went back to the office and we watched the TV. Being in flight test, this hit home hard. I didn't know anyone aboard, but people I worked with did.

It's a bit of a sore point with me. Every 3-5 years, the flight test community gets slapped in the face with this...except that the problem wasn't the working-level engineers who recommended a delay, but the managers with "go fever". Slap them in the face with it.

[Dinochrome One]

I was stationed at Adak in the Aleutians on the morning that Challenger launched. The first thing I heard after switching on my TV was a well-known newscaster reporting the accident in somber tones. I watched in shock as they replayed the video several times. In my office at the Terminal Building, Senior Chief Mike Fangman (CTCS) sauntered in and said, "Good Morning, Bob!" I looked up and replied, "No, Mike, it's not a good morning."

Just about all of our ETs and RMs were space-cadets, and it was very quiet around the workcenters that day.

[Denis]

I was stationed at Adak in the Aleutians.

Wow. I watch a fantastic documentary on German TV last week about the Aleutians. They visited Adak and Attu.

I remember the Challenger disaster. Very sad for those brave astronauts and their families. Sad for the rest of mankind that it set back the space program.

[randy]

I was in Korea, spending my time between changing from mids to days fighting a case of the Korean Crud and watching whatever coverage AFKN (Armed Forces Korean Network) was tapping into that day.

[Captain Wheelgun]

I was in college at that time (TSTI - Waco). I vaguely remember that shortly before it happened Khadafy (however the hell you spell that) had beed flapping his gums about wanting to blow up a Shuttle. I wondered if they would pin it on him as an excuse to slap him down.

[kapikui]

I was in sixth grade. I was home sick that day, and my father was laid off his job and watching Phil Donahue. A special report came on, and he (as he nearly always did) stated matter of factly and in total seriousness "We're at war with Russia." He was always certain that the only reason for interrupting programming was the onset of nuclear war. I was actually relieved when it was just the shuttle blowing up.