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In a previous thread, I asked the question of the likelihood of the STS stack surviving an early separation of the SRB using the SRB manual separation switch on panel C3:

Could the SRB's have separated successfully at 70 seconds into flight

enter image description here

Estimates ranged from the "Official" accepted answer of:

The Space Shuttle System was not designed to survive a failure of the Solid Rocket Boosters. There are no corrective actions that can be taken if the boosters do not operate properly after ignition, i.e., there is no ability to separate an Orbiter safely from thrusting boosters and no ability for the crew to escape the vehicle during first-stage ascent

To an estimate I received from a NASA engineer of 75% chance of successful separation. My educated guess, based upon herculean design efforts made to get maximum separation from the stack, is that a manual separation before booster burnout had a 50/50 chance of destroying the vehicle.

The question:

Suppose you are in the flight control room on January 28th, 1986. You are a support person for FIDO, perhaps abort support or range safety. (I don't want to label any specific party, so lets leave it general) You look up to John Aaron and have made a point to have lunch with him regularly at JSC. You have listened to him tell the story of how on the Apollo 12 launch he responded to an unexpected environmental condition (lighting strike). He used his extensive knowledge of how the systems work and more important how they fail. As a result of his extra effort, he was able to make a completely unrehearsed call up (SCE to AUX) that saved the mission.

https://motherboard.vice.com/en_us/article/john-aaron-apollo-12-curiosity-luck-and-sce-to-aux

In addition to a thousand other details, you have looked into the possible use of the SRB man separation switch in odd failure conditions. What if a booster suffered a case crack or insulation failure? What would that look like in the data? Would I be able to detect it? Could I respond to it? You have determined that the best way to detect a case breach would be visually. SRM engineers tell you that if it occurs it will propagate in seconds, so the response would need to be quick.

So your routine at launches has been to watch the data but to also watch the live feed tracking cameras to look for visual anomalies. ( like your mentor John Aaron, you do odd extra things because you see value, no matter what the "Official" position is). You don't know what you will do if you think you see an anomaly but you know the SRB manual separation would probably be the only chance, even if the likelihood of success is low. On 51L you are watching the following live feed.

At 16:39:01 you get the pit in your stomach moment (What the **** is that??). You know your John Aaron moment has arrived. Is that really a case breach?? By 16:39:04 you are sure. Months of thinking about it are upon you. Make the call, "FIDO, SRB MAN SEP NOW!!" "Look at the ROTI video!!! MAKE IT..."

Within 3 seconds, by 16:39:07, the trust between you and FIDO and FLIGHT has resulted in the call up to the flight crew "Challenger SRB MAN SEP, Dick, MAN SEP NOW!!"

The response takes another 3 seconds by 16:39:10, the SRB separation process has started.

In reality it was another 3 seconds before the RH aft ET attachment was destroyed and the RH Booster rotated into the ET and began the destruction of the vehicle.

Luckily the high winds aloft on that day assist in the separation. That and good design are on NASA's side and the SRB's separate and clear the accelerating stack.

Did 51L simply need a John Aaron mentor in Flight control that day??

If he had been, would the call up have been made??

Or was the official conclusion the correct one, ye who enter here abandon all hope ..at least till SRB burnout

Organic Marble
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Challenger Truth
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    My deepest respect and thanks, to Jim Kingsbury, head of MSFC engineering for some the ideas and details provided with regard to the Challenger accident. Jim was as close as anyone to solving the SRB problems in 1985. RIP Jim (1928-2012) – Challenger Truth Jun 15 '17 at 18:15
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    What do you think? If there was a method available to save the Challenger crew, NASA would have used it. @Challenger Truth – Starship - On Strike May 20 '22 at 22:42
  • Not necessarily true. In the STS-107, Columbia accident, the CAIB looked into the possibility that a rescue mission could have been launched and succeeded. It never happened for the same reason the Challenger was not saved. No one realized there was a problem until it was too late. This question is simply, what would have happened if you had pushed the SRB sep button prior to 74 seconds. The "why" it didn't happen is a much more complex and entirely different question. – Challenger Truth May 22 '22 at 22:17

1 Answers1

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My reading of the function of the SRB manual separation control is that it would not actually trigger a separation while the boosters were firing (bold mine):

SRB separation is normally performed automatically by the onboard GPCs; however, the flight crew can command separation through use of the SRB separation switches on panel C3. The SRB separation auto/man (manual) switch is positioned to man and the SRB sep push button depressed.

This manual function for SRB separation provides a backup for the automatic function; however, the manual function uses the same separation logic as the automatic. The automatic sequence is initiated by the software in the GPCs when the SRB chamber pressure is below 50 psi.

I haven't found a more detailed confirmation of this interpretation, however.

I suspect that even if a manual separation was available and would not have destroyed the spacecraft if attempted, it wouldn't have been possible for a controller to call for the separation and have it relayed quickly enough to make a difference.

By 16:39:07 the ET is already compromised and the shuttle's fate is thereby sealed. From the point where the controller makes the call at 16:39:04, all of this has to happen in three seconds:

  • One or two people up the decision chain (FIDO and Flight Director in your scenario) have to hear, comprehend, and unconditionally accept the call
  • Capcom has to repeat the instruction to the spacecraft
  • Spacecraft commander has to hear and comprehend the instruction
  • Spacecraft commander has to locate the SRB sep switches
  • Spacecraft commander has to operate two switches while under 3G acceleration

I don't think this is a possible scenario; just repeating the call from supporting controller to FIDO to Flight to Capcom might take 8 seconds.

Compare with the timeline of the "SCE to AUX" incident on Apollo 12 (trimmed down to a few key points):

000:00:37 Gordon (onboard): What the hell was that?

000:00:43 Conrad (onboard): Roger. We had a whole bunch of buses drop out.

000:00:56 Conrad (onboard): I just lost the platform.

000:01:02 Conrad: Okay, we just lost the platform, gang. I don't know what happened here; we had everything in the world drop out.

000:01:08 Carr: Roger.

000:01:36 Carr: Apollo 12, Houston. Try SCE to auxiliary. Over.

000:01:39 Conrad: Try FCE to Auxiliary. What the hell is that?

000:01:41 Conrad: NCE to auxiliary...

000:01:42 Gordon (onboard): Fuel cell...

000:01:43 Carr: SCE, SCE to auxiliary. [Long pause.]

000:01:50 Conrad (onboard): SCE to Aux.

The crew's first report of a problem to the ground comes at 1:02, 25 seconds after Gordon sees a problem; Capcom Carr doesn't even "roger" to Conrad's call for six seconds. In mission control, they should already have seen, by this time, that the telemetry is bad. In particular, we expect that John Aaron is seeing the glitch by this point.

It's almost 30 seconds later at 1:36 that the first "SCE to Aux" call goes up to the ship; they have no idea what Carr is talking about and Carr has to repeat the call at 1:43. It's unclear if Conrad's "SCE to Aux" at 1:50 is him confirming he's flipped the switch, but assuming that it is, we're looking at 14 seconds from instruction to operation and probably at least 40 seconds since Aaron saw the problem.

In this case, also, "SCE to Aux" is a very low-stakes call, easy to make. If the problem isn't with the signal conditioning equipment, all Aaron's call does is waste a little time, and at this point the launcher itself seems to be doing fine. An emergency booster sep on the shuttle would be at best a mission failure, and depending on who you ask, anywhere from a 25% to 99% chance of loss of crew.

Russell Borogove
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    Thank you that would be very important information. In addition the timeframe of the software would be important as well. Wayne Hale tells me that at the end of the STS program this switch had been completely reprogrammed to use it for a wheels down discrete function. I am guessing that over the life of the program the software for this switch changed. I have no idea how to nail down its function in 1986, unless someone has the code from that time frame. – Challenger Truth Jun 15 '17 at 18:31
  • The SRB Separation switch, in AUTO, simply allowed the sep commands to pass through the switch to the FF MDMs and then to the GPCs. AUTO/MAN kept that functionality but added a parallel path through the pushbutton that sent (originally) sep commands to the FF MDMs and then to the GPCs. At the end of the program this pushbutton sent a backup weight on wheels discrete instead. The takeaway here is that the manual button just sent commands to the GPCs which processed them and if accepted, sent them on to the Master Events Controller to fire the PICs. The question is what was the FSW logic? – Organic Marble Jun 15 '17 at 19:02
  • Russell is correct that the call up would have required immediate action. One quick glance at the video would have convinced anyone that a "real" problem existed, eliminating the need to question the call. I think the response time would have come down to two things, did the person have the knowledge and GUTS to make the call immediately and would FIDO and FLIGHT have questioned it or just trusted it. In reality although the ROTI camera was a live feed it was not picked up as part of the NASA select feed until the last 3 seconds before the accident. – Challenger Truth Jun 15 '17 at 19:29
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    Try this: strap a ten pound sandbag to your arm, start a stopwatch, turn away from it, speak out loud the words "FIDO, SRB MAN SEP NOW", "Flight, SRB MAN SEP NOW", "Challenger, SRB MAN SEP NOW", and only then reach to turn it off. Takes me about 8 seconds without the sandbag. – Russell Borogove Jun 15 '17 at 19:38
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    I would disagree that the Shuttle's fate was sealed when the ET Hydrogen tank was breached at 16:39:07. The vehicle continued flight until the ET attachment failed and did not explode even with the Hydrogen streaming in the SRB plume. With the SRB's gone and a leak, I think it is possible that the stack could continue to execute a RTLS. Even in the accident, the large quantity of H2 and O2 fuel did not explosively burn. Hydrogen requires the right mix of oxygen to burn properly, it probably would not have existed at 50,000 feet from a leak out of the aft portion of the ET. – Challenger Truth Jun 15 '17 at 19:52
  • What this really comes down to is there is 12 seconds between the first appearance of the breach at 16:39:01 and the destruction of the RH aft ET attachment and breakup at 16:39:13. To save the crew, the flight controllers needed to recognize the problem, relay the manual separation call to the STS crew and the crew needed to flip the switch and push the button. Separation sequence itself took 0.8 seconds. Is it possible, yes!! Is it probable, we can only speculate. However, the answer is, a method was available to save the Challenger crew. – Challenger Truth Jun 21 '17 at 12:26
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    I strongly disagree. Uncontrolled venting from the H tank, even if it chooses not to explode, is likely to destabilize the orbiter+ET, and once it's turned more than a few degrees, it's cartwheeling and coming apart. Feel free to write your own answer, but my conclusion is that there's no way to save the crew. – Russell Borogove Jun 21 '17 at 14:07
  • A LH tank is only at 22.9 psig or 37.6 ppi absolute. This is not high pressure. Since it is mostly liquid, the boil off from a leak would provide very little specific impulse IMO. I would imagine the aerodynamic factors would have more impact on shuttle trajectory that a spray of LH2 at 23 psig. https://science.ksc.nasa.gov/shuttle/technology/sts-newsref/et.html I repeat my earlier observation, the STS did not go out of control with the leak, it was the rotating booster that started the destruction not the leak. – Challenger Truth Jun 21 '17 at 20:44
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    I have received information from a member of the SAIL team in 1986, that both the SRB sep switch and the ET sep switch had minimal Flight Software checks prior to passing the signal on to the Master Events controller. In plain language, the button once pressed would trigger the event. With respect to the ET sep button the Astronaut office objected to any FSW that checked the 2% ET tank level during RTLS and that same objection was carried over to the SRB sep. button The pilot in command would make the sep decision not the computer. This means that successful or not this was an option – Challenger Truth Jul 13 '18 at 19:11
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    @ChallengerTruth, an RTLS abort was considered "an unnatural act of physics" by the astronauts, and even with an intact Shuttle and ET was a high-risk maneuver. With a leaking hydrogen tank, it's impossible. The ET needs to be nearly empty when you jettison it to keep it from colliding with the Shuttle; without hydrogen, there's no way to empty the oxygen tank (you can't burn it off, there's no dump valve, and running oxygen through the engines without hydrogen for it to burn will cause the engines to explode). – Mark Nov 02 '18 at 23:49
  • The question regarding the issues of RTLS addresses some of your concerns Mark. https://space.stackexchange.com/questions/29489/could-dick-scobee-have-flown-a-rtls-on-challenger-51l?noredirect=1&lq=1 The alternative of not throwing the SRB separation switch would seem much worse than the risks you describe. IMHO – Challenger Truth Nov 03 '18 at 19:32
  • @ChallengerTruth No. "Same type, we're go" was in response to an alarm very similar to one that had already come up earlier in the descent. From Armstrong's first "Program alarm" call at 102:38:26, it's 27 seconds before CAPCOM replies "we're go on that alarm." – Russell Borogove Jul 19 '19 at 02:05