What if Space Shuttle Challenger had survived?

[Slowpoke]

And before the Challenger disaster, there were no provisions made for a bail-out capability in any case. Had a shuttle somehow been placed in a contingency abort scenario where they were gliding over water to an inevitable ditching, they'd simply have had to sit tight until they impacted and almost certainly died.

Given the way emergency procedures were laid out (after Challenger) I'd say that even with them in place, if a launchpad situation had occured, the astronauts were as good as dead. Soyuz T-10-1 blew up less than two minutes before planned liftoff (and the pod ejected just two seconds before the rocket exploded, obliterating the launch complex). If the Shuttle escape procedures took nearly 5 minutes from beginning to end (that was the rough estimate) the astronauts would be caught by the blast just at the foot of the launch platform.

 

[Robert9640]

This is the first I've heard of this!

What I have heard is that the jet of flame and subsequent explosion took place right around Q-Max. That is, the dynamic pressure of the airflow rises with increasing speed but falls with decreasing air density at higher altitudes; given a more or less steady acceleration upward it works out that there is an altitude at which aerodynamic stress is at maximum after which the falling density trumps the rising speed. The normal ascent involves throttling back a bit just before that point, and then reboosting the main engine to resume the full-on climb, to as it were "tunnel" through that peak. The explosion was right around when they did this.

So I've always assumed the shifting accelerations at this point, or the maximal air stress on the boosters, or both, were the culprits in the exact timing. I don't know that it needed an errant jet stream to tip the balance.

In any case as e of pi says, the longer they got lucky, the longer they lived in a fool's paradise of known problems the institutions involved (NASA, Morton Thiokol) would ignore as long as they could. It took a disaster unfortunately to force an effective look at the problem.

NASA is not always like this. Sometimes if they can see a solution that doesn't stop the show and put the whole business of space travel into political jeopardy, they do something about it.

I actually think the real scandal is, there is no escape system for the crew. I can think of one but it would probably be so costly as to have scotched the whole program.

If you want to learn more about what really caused the disaster, watch the show Seconds from Disaster on National Geographic, there's an episode about Space Shuttle Challenger under the title "Space Shuttle Explosion". You can watch it on YouTube it talks about the launch, the investigation, and the sequence of events from liftoff to 73 seconds after launch, when Challenger exploded.

 

[modelcitizen]

Not a likely butterfly, but an interesting one none the less.

thank you!

 

[AndyC]

There's only one way, IMHO, that Challenger could've survived and the necessary changes to operational practices and management be made. That is for the two O-Ring seals to fail, yet the Aluminium Slag hold in place until it was returned for refurbishment. Seeing the potential catastrophe was was somehow averted would scare the living s*** out of everyone involved. And they would have no option but to implement the required upgrades.

But that is as close to ASB as you can get.

Actually, having thought of it - if this had happened (the aluminium slag holding the joint long enough - which is by no means completely improbable), I think that if anything, it would have further encouraged complacency:

"Oh look, it fails safe! If the O-rings do get burned through, the aluminium in the solid fuel forms a crust which protects the seal!"

 

[KG "Cagey"]

POST-launch survival POD = narrow window to avoid Loss of life or vehicle

The SRBs were a Criticality 1 component.
Meaning in NASA speak =
"Loss of life (crew) or vehicle" or LOCV

Any POST-launch survival POD... you MUST have the SRB seal failure happen later. For a POD, we cannot simply assign Lt. Butterfly with binoculars to duty with range safety officer Maj. Gerald F. Bieringer --or -- have Flight Controller Butterfly watching the tiny SRB pressure flux. Neither of these have time to say: " Danger Will Robinson" nor "We have a problem..." --AND-- start a change of actions to prevent LOCV. BTW 13 sec IS the minimum real time from turning the switch "SRB separation" from auto to manual to the actual SRB sep.

As stated by Rogers “Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident”
“At 58.788 seconds, the first flicker of flame appeared. ….One film frame later from the same camera, the flame was visible without image enhancement. It grew into a continuous, well-defined plume at 59.262 seconds…… Barely visible above, it grew into a large plume and began to impinge on the External Tank at about 60 seconds. Flame is pinpointed in the computer drawing between the right booster and the tank, as in the case of earlier smoke puffs. At far right (arrow), vapor is seen escaping from the apparently breached External Tank.”

So even if we place a very skilled set of eyes on the correct location AND with DIRECT contact to Flight Control... they got less than the needed 13 seconds until
-finis-.

Originally Posted by NHBL
"Could some other near disaster happen, that would be a dramatic failure, and cause a "We got lucky!" reaction? If the O-ring failed in such a way that the flame jet was venting away from the main fuel tank, could they have jettisoned it? Tanks explodes clear of the shuttle, and there's a dramatic abort?"

Originally Posted by e of pi "No, it would have been impossible. There were no abort mode involving tank jettison or (to my knowledge) early SRB separation, since the Shuttle carries essentially no fuel of its own."

So for any POST-launch survival POD... you MUST have the SRB seal failure happen later.

In OTL, "aluminum oxide and other combustion debris" resealed the joint until.... "The winds aloft caused control actions in the time interval of 32 seconds to 62 seconds into the flight that were typical of the largest values experienced on previous missions."

Again these are only POST-launch PODs:
POD option Alpha: Less Wind = Less stress on the lucky / temporary aluminum oxide seal. In this POD have the seal hold until post-Main engines throttled up to 104%; soon after this is Max-Q (the point of the greatest dynamic pressure).

So what does a minute (or more) provide?

From NASA: "The next major event is SRB separation, which occurs six seconds after … both SRB chamber pressures below 50 psi within 4.3 seconds of each other and detects vehicle rates within specified limits. These checks ensure that neither SRB is burning at separation and that the SRBs will not recontact the ET after separation. SRB separation occurs at about two minutes after launch. At separation, the first stage is complete, and the software automatically shifts to major mode 103 (second stage)."

If the seal held 1 minute more, there is a chance for SRB Separation. In POD Alpha, Max Q causes the fateful jolt. This delays the OTL failure of the SRB but still allows a visible "blow through" flame plume and scare the BLEEP out of all. This visible "oh crap!" failure cannot be a hidden failure.

Later, than Max Q fail means some seal o-ring or alum. slag holds like on one year prior flight of Discovery STS-51-C. In that case Nasa et Morton-Thiokol, bury the uh-oh until some other LOCV.

POD option Beta is identical to POD Alpha with a delay in the SRB seal failure until automatic or manual SRB sep. but instead of magic timing in the release/ sep a few seconds of damage to the ET or Orbiter occur. This very unlikely POD is the only I see for a O-ring seal failure but also a risky abort whether RTLS ( Young compared this maneuver to Russian Roulette) or TAL (that day transoceanic abort landing (TAL) site was either Dakar, Senegal -or- Casablanca).

Any post launch POD that calls for manual SRB separation is unlikely given the narrow window among visible failure, decision, and time to perform actual sep.
In OTL, The orbiter did not suffer from any "explosion," it was the aerodynamic pressure due to the separation from the external tank at flight speeds. Any POD calling for detaching the orbiter from the ET and SRB during the SRB power phase would probably cause a disaster similar to OTL and LOCV. Indeed, any incomplete (unscheduled/ accidental ) separation would leave at least one attach point that would drag and twist the orbiter around in an uncontrolled fashion and LOCV.

Pre-SRB separation accident leaves almost no options. They could not easily have early SRB nor MECO in preparation for ET separation while still under SRB thrust. That would cause the ET and SRBs to pitch into an aerodynamic side load which would repeat OTL LOCV.