Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident


Volume 4 Index


Hearings of the Presidential Commission on the Space Shuttle Challenger Accident: February 6, 1986 to February 25, 1986


Centered number = Hearing page
[bold number] = Text page.

[409] 753




Kennedy Space Center
Cape Canaveral, Florida
The Commission met, pursuant to recess, at 11:05 a.m.
WILLIAM P. ROGERS, Chairman, Presiding
NEIL A. ARMSTRONG, Vice Chairman
AL KEEL, Commission Executive Director






CHAIRMAN ROGERS: I would like to say that we're very pleased that you made provisions for us to be here so quickly and so thoroughly, and how busy all of you have been, and thank all of you for making it possible.

Secondly, I would like to suggest that, in view of the story this morning in the New York Times resulting from yesterday's briefing, that you get the appropriate people to start thinking about this criticality one problem, because it came through in the newspapers as if the waiver was of tremendous significance, and it appears as if the waiver only applied to this particular flight and this particular problem.

And so I think we may want to, after we've had a chance to talk to you about it, pointing out that this is not all that unusual, that it is not a waiver as such, that you've isolated a criticality problem and then you've thoroughly considered whether that should result in the stopping of flights or not or whether it was something that was an important factor and you had done all you could about it, but you decided to proceed.

Now, if you can show that that is also not an


[410] 755


unusual circumstance, the same papers and the same documentation would show a lot of other aspects of the shuttle program, that would help you.

If you saw the paper this morning, it sounds very serious, just in the case of the O-rings, and you waived something that was dangerous. So give some thought to how we might handle that possibly this afternoon.

MR. MOORE: Yes, sir. Let me just comment on that. We started an action yesterday going back through the entire program looking at category one items, and there are a number of them in the program, and I think we will put that particular situation in context.

Mr. Chairman, let me also make a couple of other comments quickly. We have people here from three NASA centers - the Kennedy Space Center, the Marshall Space Flight Center, and the Johnson Space Flight Center, to try to support you and your Commission here today.

You will see reports from our various teams that have been formed in terms of where they are in their analysis and the results of the work that they have done to date on this thing. And we have tried to sketch the agenda out so we can give you reports, and tomorrow, I would like to close tomorrow, if I could,




with telling you what our kind of forecast, being a schedule of activities to encompass the additional analysis that we plan to undertake, as well as the additional tests that we plan to undertake trying to validate various phase errors.

So with that, I would like to turn the meeting over to Mr. Dick Kohrs of Johnson Space Center. And Dick is prepared to cover in detail the environment and the events time line, which I think has been of high interest on your list.

So with that, let me turn it over to Dick Kohrs.






MR. KOHRS: I'm Dick Kohrs from Johnson Space Center, Deputy Manager of the NST Program Office, and I work for Arnie Aldrich.

Jess mentioned I was going to talk about environments today. I'm not going to talk too much about the environment. I'm going to give you the weather that we had on launch day during our final mission management teams, and we're building a more detailed environment and discussion of the weather that we hope to have ready later on this week.

(Viewgraph.) [Ref. 2/13-1]

Could I have the next chart, please, which is the outline.

(Viewgraph.) [Ref. 2/13-2]

I'm going to go over a few charts on the pre-launch time line and the weather summary I'm going to give you is the weather summary as we dealt with it in our mission management teams that we had the last day, starting with the L minus one review, and just highlight that for you. And then I'm going to go through the ascent time line, and then I have some detail of the data base that we used to build the ascent time line, and show you those data





[411] It is both telemetry data and data that we recreated from the photos which you're going to see next and Charlie Stevenson is going to present.

The next chart, please.

(Viewgraph.) [Ref. 2/13-3]

The first part of the time line, which is really kind of gross. It is a pre-launch time line which takes us all the way back to the ET on dock at KSC back in August of last year. The orbiter from the last mission returned to Kennedy on the 11th of November. The SRB stacking for this stack was the 4th through the 10th.

ET SRB mate was on the 10th, and it's a little bit out of sequence here. At the same time while the orbiter was in the OPF, we were putting in the Spartan Halley into the orbiter cargo bay in the horizontal.

MR. KEEL: Mr. Chairman, could I make one suggestion, that you don't use the acronyms, for the benefit of the Commissioners.

MR. KOHRS: I will do the best I can.

The external tank on dock is the ET. ORB is the orbiter. Of course, the SRB the solid rocket boosters. Then the mating of those.

The orbiter-external tank mate is on the




16th. We transferred the total stack from the crawler to the pad on the 22nd of December, secured the vehicle, essentially powered it off. From the 24th to the 3rd was the time for upgrade here at Kennedy.

In the meantime, the cargo, the IUS, and the TDRS data satellite went out to the cargo prior to Christmas, stayed in its payload canister until after the holidays, and then was installed in the orbiter here on the 5th of January.

The TCDT is a terminal countdown demonstration test. It is an all-up test of the flight vehicle with the Kennedy team that goes through a simulated countdown down to T-zero, then after T-zero they run a couple of anomaly cases in plus time just for training primarily.

CHAIRMAN ROGERS: Are you going to be explaining that a little bit later, because I really don't understand that. I don't understand what you just said.

MR. KOHRS: Prior to every flight - and it's normally about two weeks - with the stacked vehicle in its flight configuration, with the flight crew on board, here at Kennedy we conduct what is called a TCDT, which is a terminal countdown demonstration test, that exercises the flight vehicle and the flight crew and the ground crew.




We do not tank the vehicle, the external tank, during that test, and we do not run our auxiliary propulsion systems, we do not run the APU's or we do not run the booster HPU's. But it is the best we can simulate is a detailed time line countdown that we're going to do on launch day.

DR. COVERT: When you say you don't tank it, does that mean the tanks are empty?

MR. KOHRS: The orbiter OMS tanks and RCS tanks are full. And when I say don't tank, it is the external tank, the liquid launch.

DR. COVERT: And the RCS, this is the rocket control system that you use?

MR. KOHRS: Yes, that is not tanked. And the reason I put that on here, the hyper load came after the terminal countdown demonstration. The hyper load is the OMS and RCS, et cetera. And I apologize for these acronyms.

GENERAL KUTYNA: Dick, one detail on stacking. Did you take out one segment? We heard the aft center segment?

[412] MR. KOHRS: That's going to be covered, I think, on this afternoon's agenda. You will have a detailed discussion of that. Here I was just trying to give you a view of how things progressed here at KSC.




CHAIRMAN ROGERS: But as far as TCDT, did you take and have the astronauts out there and the whole crew?

MR. KOHRS: Right.

CHAIRMAN ROGERS: And you planned to try to simulate what it would do in terms of time, what each person has to do?

MR. KOHRS: Right.

CHAIRMAN ROGERS: Does any inspection occur at that time?

MR. KOHRS: Not to my knowledge. We don't really do any detailed inspection. It's just a dress rehearsal.

MR. RUMMEL: Does that include a system checkout?

MR. KOHRS: The best we can. It powers up the orbiter subsystems. We don't - the fuel cells are not powered up. We use ground power and the best we can simulate we power up the guidance system. Primarily, it is the guidance system we power up.

MR. RUMMEL: How about the telemetering data system?

MR. KOHRS: All the data is telemetered to the ground through the umbilicals. Some of it is RF and that data is recorded.




MR. RUMMEL: But at that point you check the propellant meter system out to be sure all the circuits are working?

MR. KOHRS: To be sure all the data flows and all the red lines are passed that apply to that dress rehearsal, yes, sir. It is as close as we can get to - the best words are a dress rehearsal, with the flight crew and the ground crew.

CHAIRMAN ROGERS: Dr. Ride was just saying, in addition, what happens to the engines?

DR. RIDE: Well, we don't - I guess the best way to put it is that it is a dress rehearsal for the crew and the launch control center and the orbiter systems, and you go through an entire countdown, including the data and information that you would be getting on launch day.

In the launch control center and on board, you go through the regular countdown, and really you go down to zero. But we don't light the engines, obviously, and you don't load the external tank, and you don't start the auxiliary power units, and you don't light the engines. But basically everything else is a dress rehearsal for the launch.

CHAIRMAN ROGERS: And that is for the purpose of a dress rehearsal. You don't learn anything about




the condition of the shuttle at that time?

MR. MOORE: No, you do learn about the orbiter system and so forth, sir, at that time.

CHAIRMAN ROGERS: What do you learn?

MR. MOORE: We learn if some of the orbiter avionics systems on board are functioning properly. We also learn if we have got any problems with the ground processing system to get ready for launch in the launch control center.

So we do learn a lot, and that allows us to put in any kind of corrections required prior to actually doing the launch. That is a very important milestone that we go through on each mission.

[413] CHAIRMAN ROGERS: And I suppose you will be telling us later what you learned?

MR. MOORE: Yes, sir.

MR. SUTTER: When you take the system out of the assembly shed and you put it onto the moving transfer plate -

MR. KOHRS: The mobile launch platform and the crawler.

MR. SUTTER: This introduces - you take it under one loading condition and you put another load on, like the solid rocket boosters. How is that controlled? Is that done the same way every time, and




are there checks after you take it from one place to another the shifting in load hasn't affected the mating between the solid rocket boosters and the external tank?

Or could something happen there to say affect the loading of the joints and the seals? And how is that, you might say, inspected to make sure that a movement like that is consistent and in line with all of the documented specs?

MR. KOHRS: The best way I would describe that is, when we stack the vehicle in the vertical assembly building we have the strain measurements of the holddown posts, and that data is recorded as we stack the vehicle. We have level-in requirements that the vehicle has to be to a certain level requirement to get the loads balanced between the eight posts, and I think that criteria is something like 10 thousandths to start a stack.

We have criteria dimensionally that says, when you get it to the top where the ET attaches, you have to have a certain dimensional criteria that you have to pass.

MR. SUTTER: But do you continue those measurements as you make these transfers?

MR. KOHRS: Yes. After the vehicle is stacked, you roll out to the launch pad. Then you again




have measurements to tell you what the loading is on the stack out on the launch pad.

And we also have that data coming down during the liftoff of the loads that we are putting into the holddown posts. And you will see in my later time line one of the things that we haven't completed yet is to accurately reconstruct the liftoff loads based upon that data, strain gauge data, then based upon the film analysis, to make sure that this vehicle has lifted off within our envelope that we had on the previous 24 flights. And that is ongoing.

MR. SUTTER: So you are checking those loads against your previous flights?

MR. KOHRS: Yes, and the film data, because we have film data in terms of the drift as you go out of the ascent.

MR. CRIPPEN: Dick, just for clarification, what were the measurements that you had on the holddown points? We don't instrument, nor do we measure, the joints per se after the stacking?

MR. SUTTER: What about the loads attached between the solid rocket booster and the main tank? Is that an important load that could vary?

MR. KOHRS: Let me back up. In the OFT program which you saw last week, which was our first




five flights, we flew one - we flew one of two that it was heavily instrumented, as were the SRB's, as were the struts.

[414] We have gathered our data base during that time frame and have used that data base to say, if we stack within these dimensional tolerances we're going to be within our load acceptance.

MR. SUTTER: But since that time, you've changed the structural characteristics of the center tank. You took 5,000 pounds out of it. You've increased the power of the solid rocket boosters, not by much but like about five percent. And you had a margin you were dealing with at that time in those other flights.

But what has happened to that margin for this flight?

MR. KOHRS: Analytically we have done that. We can show you analytically what the margins are with the new configurations. We have not passed - STS-5 had what I would call a heavily instrumented DFI. That is development flight instrumentation.

That is not real time. It was recorded in on-board recorders, and once we landed we analyzed that data on the first five flights. But based upon that data, based upon our structural models, we have analyzed




what the new loads are, and it is based upon that that we proceeded.

MR. SUTTER: You are talking about doing some more tests, though, to verify that?

MR. KOHRS: Yes, sir. And I think George Hardy is going to talk a little bit later, I think he is, on that.

The hypergolic load, which is the OMS and RCS, was done on the 16th, and on the HPU, is the solid rocket booster.

CHAIRMAN ROGERS: Just before we got to that, what does that mean, hyperload? What did you do?

MR. KOHRS: Sir, the OMS and RCS, which are our maneuvering systems on board the orbiter, are hyper propellant, and roughly the OMS is in the neighborhood of 23,000 pounds and the RCS is in the neighborhood of 7400 pounds.

GENERAL KUTYNA: These are hypergolic propellants. They don't need any ignition.

DR. COVERT: And the OMS is the orbiter maneuvering system. That's the rocket that allows you to rotate.

MR. KOHRS: And the reaction control system are the small jets described last week.

MR. MOORE: Dick, let's make sure we cover




each of the acronyms up here, because that is a communication problem we've got with some members of the Commission. So let's make sure we explain the acronyms.

MR. KOHRS: The data on the 17th is the HPU, which is the propulsion system for the SRB's. It is very similar to the orbiter's auxiliary propulsion system. And we did roughly a 20 second hot fire prior to launch in the 17th time period.

And finally, at 1/23 we picked up a point in our countdown that is called the beginning of the final count or the beginning of the terminal count, and that begins at T minus 43, which in calendar days, 43 hours in calendar days is roughly three days before the planned launch.

You've got some built-in holds, but this is in our clock counting terminology.

MR. RUMMEL: Could you explain the HPU a little more fully?

MR. KOHRS: The HPU and the SRB control the actuators that drive the nozzle for the flight control.

MR. RUMMEL: How is it powered?

MR. KOHRS: By an auxiliary power propulsion unit, very similar to the orbiter, which is basically a hydrozene powered system. And the only major difference


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between the orbiter and the SRB is the orbiter has some requirements where it has to go through the total ascent. It has to be able to restart it on flight, and it's used during entry for elevon control and surface control.

The SRB HPU basically only needs to work during this 20 seconds prior to liftoff and through the 128 seconds of burn. It is recovered, it is reused for following flights.

MR. RUMMEL: Thank you.

MR. KOHRS: Could you put up the next chart, please?

(Viewgraph.) [Ref. 2/13-4]

What we have done here at Kennedy is, for this flow which involves the orbiter, the external tank, the SSME, and the solid rocket boosters, we have gone back and are reviewing all of the paper that was generated during that flow, and we have appointed special teams, different than the guys or the people that did the work, to go back and relook to satisfy ourselves that that paper was properly closed out.

To date, that amounts to about 2,000 pieces of paper of different actions and things that were done since the 26th of August. That data we estimate we will have complete probably within ten days to two weeks.




MR. WALKER: Is that a fairly typical level of paper?

MR. KOHRS: That is typical of a flow. And the chart on the right is just an example. I won't dwell on it, but it is an anomaly that occurred when the orbiter landed at Dryden from its last flight, where we had a platform interference with the orbiter and we nicked a couple of tiles. And the people went back to relook at that to make sure that that was satisfactorily closed out.

CHAIRMAN ROGERS: Is there anything in that time line that is of significance in terms of anomalies or anything else that was suspicious that might have affected 51-L so far?

MR. KOHRS: No, sir. The only thing I would think up here - and we've had a lot of weather discussion - is we did go to the pad.

CHAIRMAN ROGERS: Well, we will come to that later. But I'm just thinking as far as this chart, the time line, is concerned, there is nothing unusual about it, and this was the way you normally handled it, and what you're doing is describing how it worked, and it worked in this case without any problem as far as you could tell?

MR. KOHRS: Yes, and the amount of paper we




created on this flow I would say is typical of other flows.

The next chart then is going to take you from the T minus 43 point, which is the start of - the next chart, please.

(Viewgraph.) [Ref. 2/13-4]

- which is the start of the terminal count. And it extends, and I will have to go through my acronyms, it extends from the pickup at 10:00 a.m. on the 23rd of January, goes through our final launch down here to 11:38, which was our launch time.

Basically, at T minus 43 hours there's a standard set of terminal count flows that were being followed with no unusual circumstances. On the 25th at 11:00 a.m., we had our L minus one day. And "MMT" stands for mission management team. We talked a little bit about that last week.

Next chart, please.

[416] (Viewgraph.) [Ref. 2/13-5]

At that briefing the projects and all of the cargo gave their go for launch. The only questionable item we had on that day is, we had a questionable weather predicted for the Sunday launch on the 26th.

CHAIRMAN ROGERS: How large is that MMT team?

MR. KOHRS: We have some charts. The MMT team




on L minus one is done both here in person and by telecon around our loop. If you count up all those people, we probably had close to 100 people: primarily all the field centers, their contractors, the cargo people and their support, the Kennedy people and their support here locally.

CHAIRMAN ROGERS: Are the telecons recorded?

MR. KOHRS: No, sir.

CHAIRMAN ROGERS: Were there any summaries made after the conversations?

MR. KOHRS: Normally, at the L minus one mission management team the record is - the presentations that were given at that meeting, that is in the record.

CHAIRMAN ROGERS: But no record of the comments were made?

MR. KOHRS: No, sir, no formal record has been made. That is a good point. At the FRR action items are documented and, as I said last week, we close out the action items that we have from the FRR at the L minus one, and that closeout of all the open action items are documented and in the record as closed out formally.

CHAIRMAN ROGERS: When you say "closed out," you mean checked? Everybody says okay?




MR. KOHRS: Jess Moore and Arnie Aldrich sign them.

MR. MOORE: And the generator for the action item provides the data for the action item. They are then reviewed by and signed off by that person. They are then signed off by the responsible project manager, and they are signed off by Arnie Aldrich at level two, and then they're presented to me and I have the final signoff on them. And that is the formal action for any signoffs that we have at this L minus one day review or the flight readiness review, as we discussed before.

We've got records of those.

CHAIRMAN ROGERS: And everyone who signed off, the only real question then was the weather?

MR. MOORE: The only real question that we had at the launch minus one day review was in fact the weather. There were no system problems identified at that time.

CHAIRMAN ROGERS: And how did you leave the weather?

MR. KOHRS: I was going to go through that next. The right chart is a couple of bullets on each of our meetings on the weather. Now, as we meet later this week or next week, we will give you a detailed briefing. We actually have charts that were presented




at the meeting. We have the videotapes that were presented at the meeting.

But if you look at the top of the chart of the right, at that mission management team, the cold front approaching, that was forecast for low clouds and rain at launch time. Temperature forecast for launch on that day was going to be in the mid-60's at launch time. And just for information, it was also reported at that meeting that the rainfall that we had at the pad since [417] the rollout on the 22nd was approximately seven inches, versus a normal of two and a half inches for this time period.

DR. RIDE: Did anybody express any concern over that? Were there any systems that thought that might be a problem?


MR. ALDRICH: I would like to comment, Sally. We did discuss that throughout this period, about the amount of water that the orbiter might have picked up in terms of additional weight, and that was closely monitored, and the amount of waterproofing on the orbiter had been reviewed to show that we were well within the minimum pickup.

DR. RIDE: And I assume that all of the appropriate systems people, like SRB people, to pick




relevant example maybe, had heard that there was more rain than usual?

MR. ALDRICH: That was clearly reported in a very formal way, the same way we're reporting it today.

CHAIRMAN ROGERS: Had there been any evidence that on previous launches that rain had created any problem?

MR. ALDRICH: Early in the program, we had a problem with water pickup in orbiter tiles, and we have had an ongoing program of techniques to waterproof the orbiter and prevent that, both from the extra weight that was carried and from the freezing of that water in orbit, causing tiles to fracture as the freezing expands.

That has been well understood and researched through the whole flight program, and there are techniques and ways to deal with it, including the ones that were discussed here, including 51-L. And we felt that was well within bounds.

CHAIRMAN ROGERS: But that related to the tiles and not to the launch itself, or to any danger involved with the launch from the view of the amount of rainfall?

MR. ALDRICH: It related to the launch with respect to the orbiter and any related causes or dangers




that might be involved with the launch of the flight.

CHAIRMAN ROGERS: I guess maybe let me ask the question a little differently. Did you have any previous experience with rainfall that had created any possible problem with the launch or with the O-rings?

MR. ALDRICH: I don't believe so.

MR. MOORE: I think George Hardy from Marshall Space Flight Center, I would let him comment on that.

MR. HARDY: No, we had no problems of any kind that we attached in any way to the rain.

MR. WALKER: I understood that the putty was thought to be rather sensitive to moisture and there was a concern that humidity might somehow affect the putty.

MR. HARDY: There is a procedure for handling the putty and storing the putty prior to the time that it is applied. And then of course the segments are stacked. And part of this procedure is relative to the fact that we want to minimize the moisture pickup of the putty.

The experience that we have had is that when the putty does pick up moisture that it gets tacky and sticky and softer.

DR. COVERT: Is there a seal at the bottom of the skirt, or the nozzle, rather, so that the inside of the rocket is isolated from the environment?


[418] 777


MR. HARDY: Yes, Gene, there is a plug, what we call a nozzle plug, that is bonded in place in the nozzle while it is sitting on the launch pad or while it is being shipped. And it does have thermal protection system material on the bottom of it.

DR. COVERT: Thermal or humidity?

MR. HARDY: Thermal. Now, the bond, the bond itself of course forms a seal, which we think is a good seal. We don't propose it to be a hermetic seal, but we do think it is a good seal.

DR. COVERT: This is actually an insulator. When you start the main engines, with current circulating around, it can come up and cause a problem.

MR. HARDY: That is correct.

DR. COVERT: Is this an epoxy seal?

MR. HARDY: Yes, it is a epoxy seal, and that plug actually blows out when we ignite the solid rocket motors. I forget the exact pressure, but it's 15 or 20 or 30 psi.

MR. MOORE: I was going to say, Mr. Chairman, that at the time of this launch we had not - we were not aware of any water experiences in any of the joints. We are looking at the water history now for the program in a lot of detail, and we're trying to see if in fact there could have been some water in that




particular joint.

That is one of the failure analysis scenarios that we are looking at, and we are trying to go back in the history and processing of all of the segments and retrieving of all of the segments to find out if we did see any evidence of water. I did hear a report the other day that we did see one instance potentially where we did have some water, and we are looking at that right now.

And I do not have a detailed report to offer you now, but I will tell you that my task force is really looking at that, because water in this joint in my opinion has to be looked at very, very carefully.

CHAIRMAN ROGERS: Well, I think that answers my question. In other words, you still have some suspicion that the rainfall might have affected the joint?

MR. MOORE: Yes, sir.

CHAIRMAN ROGERS: And you are studying that.

MR. MOORE: Yes, sir.

CHAIRMAN ROGERS: But at the time of the launch you had no reason to think that the rainfall in and of itself was part of the problem, going to cause a problem?

MR. MOORE: That is correct. That was my




feeling at the time, and I will let Dr. Lucas and Arnie and the other people who sat and made the final critical decision that we had no reason to believe, other than the tile, absorption of water had anything to do with any concerns relative to the systems in the shuttle.

DR. LUCAS: Yes, I am Bill Lucas. That is correct, at the time of launch we had no evidence that water would be a problem.

In the first place, these joints are put together with very heavy grease on the tang and on the clevis side of it, and then a bead is put around the top. That is primarily to protect the joint from corrosion as you tow it back through the sea.

But we had not had any evidence that water had been captured in those joints. Since that time, since the launch, we have heard that there may have been one instance in which there was evidence of water in the joint, and we are pursuing that to see if that is in fact the case.

[419] CHAIRMAN ROGERS: Without drawing any conclusions, of course, how far back was that experience?

DR. LUCAS: The experience that has been reported to me, which is not confirmed as far I'm concerned, is on STS-9, which was - and this would be




25, so that was several launches ago.

MR. MOORE: STS-9, sir, I think was launched in November of 1983, and it was the first space lab launch in the shuttle program, I believe, November of 1983, I believe.

MR. ALDRICH: Mr. Chairman, could I make one more comment about the weather, because over and over again that will come into our discussions. This mission management team focuses extensively on the weather for every launch, because of a variety of considerations with respect to the orbiter - the fragility of the tiles from ice impact, the crosswinds at our landing site, and the approaches for the landing site.

I mean, we have one here right at Kennedy adjacent to the launch pad. So we had extensive discussion of the weather and a review for the orbiter, and that is why that comes up so much in our discussion.

CHAIRMAN ROGERS: I understand that. But for our purposes, the first objective we have, or the first request by the President to this Commission, was to try to find out the cause of this accident. We have other considerations later on. But I mean, that is our first mandate or part of the mandate.

And so I am trying to focus and we're trying




to focus on things that might relate to that. And obviously, there are a lot of aspects to the weather. The rainfall itself, there was unusually heavy rainfall, and the question I was asking, did it occur to you that that rainfall in and of itself might affect the joints?

And now of course you're telling me you didn't think so at the time, you are reviewing the previous launches to see, and there is one that might be suspicious.

DR. LUCAS: Mr. Chairman, may I clarify one aspect? And George Hardy has just reminded me that if this moisture or water was uncovered allegedly in the joint during the process of stacking, it was necessary to de-stack. The vehicle was de-stacked, one segment was removed from the other, and water was discovered and of course removed.

To our knowledge, STS-9 did not launch with any water in the joint.

GENERAL KUTYNA: Jess, one last rainfall question. How many launches experienced this much rain since the orbiter got rolled out to the pad?

MR. MOORE: I don't have the data. We will have to go back and track that data and give you a history of the rainfalls as a function of launches. Early in the program, a lot of flights set out a fairly




long period of time and so forth, so there have been instances where we've seen a number of instances of rainfall.

GENERAL KUTYNA: The point I'm trying to make, this is not necessarily the wettest orbiter you ever launched?

MR. MOORE: Well, I don't know that, Don. I can't commit to that right now, but we are going back and researching that weather history and so forth on the systems.

MR. ALDRICH: A clarification. We reviewed how much water we thought this orbiter had picked up and we felt the pad protection, the launch pad weather protection, and the water [420] proofing caused this orbiter to not be excessively heavy, and thought we had a maximum of 200 pounds, which is a low number given the total an unprotected orbiter could pick up and well within the bounds that we've accepted on other flights. And we felt it would fly with no significant effect.

MR. RUMMEL: In addition to the water question, I assume you're calculating the loads imposed on the various attachment fittings, both the shuttle and the SRB, as best you can that were experienced during this flight, is that correct?

MR. KOHRS: Yes, we are.




MR. RUMMEL: Do those calculations take into account what has to be a very complicated structural dynamic situation between the main components? Have you found any structural deformations? Has this occurred? Is this being done?

MR. KOHRS: Yes, sir. I will show you what we call our detailed ascent reconstruction. We are probably a couple of weeks away from the detailed reconstruction of the loads that we think we saw on launch date, based on the environment, which primarily is the winds aloft environment.

The liftoff loads we got: At SRB ignition we had the strain gauge data, and the wind data we got from our wind balloons that were sent up, and that is ongoing. I will show you some charts later that will show you the wind profiles and some of the Q levels. And I have some backup charts that will show you in a preliminary fashion, for example, the strut between the SRB and the ET, what we predicted pre-flight and what we have reconstructed to date based upon the winds of the day.

And Tom Moser will also show you that.

MR. RUMMEL: Does the recorded information show the relative G loads between the shuttle and the SRB's and the main tanks?




MR. KOHRS: I don't have it today, but the reconstruction does do that.

MR. RUMMEL: It does to that?

MR. MOORE: Yes, sir.

MR. RUMMEL: Do you have similar data on earlier flights. I'd be interested in how the structural loads might have been affected by the dynamics between the main tank and the SRB.

MR. KOHRS: Yes, sir, we have it for all of our flights up through STS-5. We had our struts instrumented, so we are actually getting measurements for that I call our OFT flights or operational flight test program. We have that data, which shows you what the interaction was for those five flights, and then we have the analytical data modeling that tells you, based upon the wind measured that day, what the strut loads and what the vehicle loads were for all of the flights.

MR. RUMMEL: You don't know yet how that came out for this flight?

MR. KOHRS: Well, on a couple of preliminary things, for example the strut that holds the orbiter - I'm sorry, the external tank, to the SRB, we have reconstructed that, and the load levels are down into like the 50 percent level.

MR. RUMMEL: Were there any unusual wind shear





MR. KOHRS: Yes, sir, and I have a chart here later that will show you that we did have a wind shear around the 60 second time frame. And I think what we will build during these [421] scenarios is a combination of the wind shear and the other events probably were some combination to this failure scenario that is being developed.

And I will show you here what the effects were of the wind component of that. The winds, though, were based on our balloon releases. We released balloons at 13 hours before launch - actually, it started 48 hours before launch - 24 hours before launch, 13 hours before launch, 7 hours, 5 hours, 3 hours, 2 hours, and then 10 minutes after launch, on this particular flight we did.

DR. COVERT: Does the balloon data correlate with the plume distortion in the 35, 40,000 foot altitude level?

MR. KOHRS: I will show you that, based upon the wind data and what the actual vehicle rates were doing, we have a delta force that we cannot account for.

DR. COVERT: But the plume data also shows a strong shear in this altitude.

MR. KOHRS: And that is the analysis still ongoing.

GENERAL KUTYNA: At Vandenberg, when we let




our balloons up, since they go much slower than the rocket does, the darn balloon goes way the heck down range before it gets to 50,000 feet, while the rocket goes up through here. Do you have that same problem?

MR. KOHRS: We have the same problem. We have that modeled, and downrange we are looking at a device called a wind profiler, which is installed here at Kennedy, that can give you more accurate wind data. And that is ongoing.

MR. SUTTER: You know, the wind shear and wind is an instantaneous effect. What does an hour before reading do for you to tell you what kind of wind shear?

MR. KOHRS: Well, we have developed our math models based upon a lot of historical data, for every month of the year, for different times of the year. And in our wind models we put in what is called a persistence factor, that says that the wind is this at seven hours and we've got the data from the last 48 hours; mathematically, from a modeling standpoint we predict ahead, and that is why we try to launch our balloons as close as possible to launch.

Now, our data has shown - and we generate the load profiles for each of these winds, and our data has shown a pattern that pretty closely follows the last 10, 12 hours.




MR. RUMMEL: Has there been, may I ask, any evidence of fatigue or other structural problems in the reusable part of the attach fittings during past launches?

MR. KOHRS: George, you may have to answer that for me.

MR. HARDY: I have no recollection of that. We will check that. Well, my recollection is there has been no problem.

MR. WAITE: Along that line, you were on the pad for a month, is that right?

MR. KOHRS: The 22nd to the 28th.

MR. WAITE: What load margins are represented with the weather conditions? How much does the weather put into that once it's on the pad?

MR. KOHRS: The vehicle is installed at the vertical assembly building, then rolled out to the pad.

MR. WAITE: I mean while it's on the pad, do you monitor it during that month to see what the load history is?

MR. KOHRS: No, I do not believe we do. We do not monitor the holddown posts during the time it is on the pad. We do it after rollout and then we do it prior to launch, and of course we have got the data during the launch phase.

[422] DR. COVERT: Do you monitor loads while it is




on the moveable vehicle?

MR. KOHRS: No, we don't.

MR. LAMBERTH: Dick, we've looked at them. I need to go back and look at the effect. And I'm Horace Lamberth, I'm sorry, Director of Shuttle Engineering for KSC. We have looked at all of the data that we took on the initial stacking, during the launch, and prior to launch.

But I will go back and see in the periods between that.

MR. WAITE: Well, is it ten percent of max load or five percent? It may be so low it's not significant.

MR. KOHRS: It is very low. We will have to get to those details.

CHAIRMAN ROGERS: Why don't you go ahead. I think we're getting ahead of you, and you've probably got other people that have information. So why don't we move along.

MR. KOHRS: Okay. If we move to the top of the right-hand chart, I've got you down to the point where we had the questionable weather, and what we did at the first mission management team meeting was decided to meet that night at 9:30 for the purpose of reviewing the weather.




At 9:30 we went through the weather briefing. Again, here's just a real quick summary, but essentially the cold front had progressed this way, as predicted. The forecast was unchanged, and so the mission management team, with all concurrences, decided not to start the tanking, which normally would have started about 1:00 a.m. that next morning.

CHAIRMAN ROGERS: And what was - the decision was to scrub?

MR. KOHRS: The decision was not to start tanking or try to launch on the 26th.

CHAIRMAN ROGERS: Why was that decision made?

MR. KOHRS: Primarily, on the top, we predicted the multi-layer cloud decks, and in our launch criterion we have both ceiling levels for return to the launch site and we also do not want to do ascent through any rain. That is our basic criteria that told us that if we tanked -

CHAIRMAN ROGERS: So it was cloudy and rainy?

MR. KOHRS: Right. So if you come down then, we decided to come in at 2:00 p.m. here on Sunday to again review the weather, and the weather here is listed on this set of bullets. And by that time the cold front had moved into the area. The weather, though, had not deteriorated as quickly as projected the day before.




However, the weather forecasters thought that a clearing was behind the frontal passage, and the only concern then on that day was the high forecast of surface winds and upper air winds for that day. We decided at that meeting, though, that we would go ahead and proceed with the tanking, and that was given at this time frame, and then the scheduled launch time was 9:37 a.m. for the 27th, which was a Monday.

On the 27th, we basically started the tanking at 1:00 a.m. For the 27th launch, we started the tanking at 1:00 a.m. in the morning. The ice team at 5:00 a.m. went out, like they do on all launches, to do a vehicle inspection.

And our ice team and their criteria is basically one of ice on the external tank, and primarily it is concern of ice formation that during ascent could cause debris that would impact the orbiter. And we do have a set of criteria that says in certain areas of the tank, like very forward, the criteria is no ice, and in other places of the tank you can have up to a sixteenth of an inch, and by analysis, it is areas that if it came off would not damage the orbiter.

[423] That ice team came back at 5:00 and gave that go.

CHAIRMAN ROGERS: Can I interrupt you just a




second? I guess then that the consideration of ice did not relate to the launch itself; it related to whether there would be damage to the orbiter. But you didn't think the ice on the external tank would impair the launch capabilities?

MR. KOHRS: Yes, sir, on this day. The next day it changed a little bit, because then we had the concern for the facility ice. And I will go through that.

MR. WALKER: Could you say a little bit about how much ice was on the external tank? Is that documented?

MR. KOHRS: That is documented. We have an ice team, and it's headed by Charlie Stevenson, who's going to be the next speaker, to show you the film. But that is documented as a record. We are documenting that data, and also I believe they take voice recorders on their ice inspections and that data - don't they, Horace?

Anyhow, that is documented.

VICE CHAIRMAN ARMSTRONG: Is this ice only - are you talking about glaze ice or are you also talking about frosting?

MR. KOHRS: We're not too concerned about frost. The areas of concern are ice that forms




protuberances, where we cannot have the right insulation, when we've got the expanding joints, because when the tank is loaded it essentially shrinks and some of our joints really become exposed because the tank has shrunk, and the members attaching it are changing load during the loading.

We are concerned about protuberance ice, but mainly it is acreage ice on the launch tank.

And this same team has gone out and done this inspection, basically the same people, I would say 85 percent of the same people, since STS-1, have gone out and done this ice inspection.

What happened at 9:18, we had a hatch anomaly, which Arnie Aldrich talked to you about last week. Because of that hatch anomaly we got ourselves into, we had essentially - our IMU's had come out of their realignment. That's inertial measurement units.

MR. MOORE: That's the gyros and so forth, for attitude control.

MR. KOHRS: And we have a constraint that says that they can only give you a hold time of 90 minutes. So as we were working on a hatch anomaly we had a three hour launch window. We decided to go back and do the IMU realignment, which delayed the launch to 12:37 at the close of the window.




And at 12:36, what happened to us here is we had a launch scrub. We had a high return to launch site crosswinds, and our criteria there is not to exceed 15 knot crosswinds. Based upon that data, we decided to call off the mission for that day, and we then proceeded.

And our normal course of business as soon as we can is to de-tank the external tank of propellant, and that started at 12:41. We then decided to have another review with the team to talk about a launching attempt for the 28th. That meeting was held at 2:00 p.m. on the 27th, primarily to talk about the weather forecast, which is on the bottom chart on the right.

And here again, it was forecast continued clearing, decreasing northwesterly winds, but the temperature there was expected to be below freezing, into the low twenties in the early morning hours, primarily around 6:00 a.m., but over a period of below 32 degrees for about eleven hours.

[424] We had a concern expressed at that meeting on our ice on the facility. That goes back to January of 1985 on the 51-C launch, where we also had a launch, I call it, a scrub, where we had below freezing temperatures and we decided not to tank because of the weather forecast, and we did launch the next day of




51-C, the following day.

CHAIRMAN ROGERS: What does "the capability of facility" mean?

MR. KOHRS: The facility has a lot of circulating water for things like eyewashes and water spray after liftoff, where we keep that water primed ready to use. In the meeting, we decided that the way to - I'm getting a little bit ahead of myself, but we decided that that water would probably freeze and bust some lines.

So we decided to go out and do what we call a little trickle, like you do with your water faucet at home to let the water run overnight.

The bottom line there is that at that weather briefing the temperature was forecast to be near 30 degrees, and I put the actual temperatures down there. At 9:00 o'clock it was 29 degrees, and at 10:00 o'clock it was 32 degrees.

DR. RIDE: You said that before 51-C you were faced with similar weather forecasts of below freezing and you decided not to tank. This time you decided to tank. What did you learn since 51-C?

MR. KOHRS: What happened of 51-C, Sally, is we did not have the procedures in place for keeping the facility from freezing. We have a terminology, Horace,




that is called freeze plan. For 51-C we did not have that, and the night that we had our low temperatures we actually broke pipes on the launch pad, and so we had to take the next day to really repair those pipes before we could get into the final launch count.

This method of trickling water kept the pipes from freezing. However, to lead you down that path, we gave the go for a tanking. Tanking was to start at 1:18. It was delayed because we had a launch processing system, LPS, anomaly in the flow of the vehicle.

In the meantime, this ice -

DR. COVERT: Wait a minute. That is an image I have difficulty accepting, the flow of the vehicle. Do you want to explain?

MR. KOHRS: The tanking of the vehicle, the processing flow, is what I meant to say.

DR. COVERT: The processing flow?

MR. KOHRS: The tanking flow.

DR. COVERT: So you're pumping in oxygen, liquid oxygen or something, and it's not right?

MR. KOHRS: The control system, the launch processing system, which is a computer system, had a problem with one of their control cards that would not allow us to safely tank. And so we took the time out to fix that.




DR. COVERT: Fine, I see now.

MR. KOHRS: Which got us into about a three hour delay. So during that time frame we decided to send the ice team out at 1:30 a.m. in the morning to take a look at the facility, and at that time they reported that we had heavy ice accumulation on some of our areas, especially where we had this trickling water.

[425] We did start tanking at 3:55 a.m., and then roughly three hours later at 7:00 a.m. the ice team went out and made their normal inspection of the vehicle, primarily concerned again with the external tank.

In the meantime, we decided that, based upon their report, we needed to have another review of the temperature data and we called a mission management team, which convened at 9:00 a.m. on the morning of the 28th to re-review the ice condition at the pad.

The concern at this meeting, though, was primarily, was the concern that ice that was on the facility during the ignition of the main engines and during the liftoff of the SRB would fall off of the pad or break loose from the facility, aspirate into the flow of the vehicle, and a potential damage to the orbiter.

We had an extensive review, and Arnie discussed it last week with the orbiter project, at this




meeting, and after a lot of consideration, we had a go for launch on that day.

CHAIRMAN ROGERS: Is this a fair summary, then: that the ice problem was assessed in terms of the facility, whatever you call it, the capability of facility, which means the water runs in the orbiter, I guess, and you checked that out and you checked out ice conditions because you were worried about the condition of the orbiter?

Was any check made by the ice team or anybody else how the whole temperature would affect the external tank or the booster rocket?

MR. KOHRS: The external 7:00 o'clock ice team inspection was a normal inspection. They did their normal temperature survey of the external tank, and as a matter of course they surveyed the SRB temperatures.

CHAIRMAN ROGERS: What did they do in that connection, the SRB temperatures?

MR. KOHRS: They just recorded the temperatures in some locations on the SRB and the external tank.

VICE CHAIRMAN ARMSTRONG: How did they do that?

MR. KOHRS: Horace, you will have to help me on that.




MR. LAMBERTH: Yes. The ice team that went out at this time, basically the vehicle was very clean of ice. They did it with an infrared pyrometer all the way up and down the stack, and that is just for a reference item.

DR. RIDE: You're going to go into that more?

MR. LAMBERTH: We hadn't planned on going into it today, but we would go into it later.

VICE CHAIRMAN ARMSTRONG: I think we would like to have a review of that.

CHAIRMAN ROGERS: Why don't we talk about it a little bit today, because I have trouble, if it was that cold and you knew that the orbiter - I mean, that the booster rocket might be affected by cold, why wasn't more attention paid to that aspect of it?

MR. CRIPPEN: I was just going to say that they do and did take temperatures of the solid rockets. However, they had no criteria with regard to that, and that was just a matter - I don't want to mislead you that they were looking at the SRB temperatures.

MR. MOORE: In the meantime, I guess Marshall in the Marshall projects office was looking at temperatures and so forth, and maybe Dr. Lucas can speak to that.

DR. LUCAS: Well, I can comment on that.


[426] 799


There was a meeting, which we're going to go into in detail, I believe at 8:00 o'clock tomorrow, that evening which I believe went on from about 11:00 p.m. until about 11:00 a.m., at which time it was concluded that it was satisfactory for the launch, the solid rocket booster, and in terms of the forecast that we had.

DR. RIDE: What were the temperature readings on the SRB's from the IR readings?

MR. LAMBERTH: Sally, we've got those documents and we've got some discrepancies between the left and right that we are running tests on now trying to understand those readings and how much they were affected by the night sky. And we had a team out last night looking at that, and we're trying to correlate that to give the best temperature estimate we can.

The left-hand SRB read what you'd expect, in the 23, 25 degree range. The right-hand shows lower readings than that. We feel like the right-hand is somewhat lower than the left due to the night radiation, but we don't believe they're as low as some of the readings we have, and we're trying to understand those and be able to put some logic into those.

MR. MOORE: As I understand it, Horace, we did see some readings as low as, data I have heard - and I haven't seen the actual data - is down as low as 10




degrees, is what the IR pyrometer said.

MR. LAMBERTH: Yes, we had some readings on the right-hand SRB as low as nine degrees and seven degrees on the nozzle. We do know from last night's data that that is affected some by the factor that you have a night sky looking from that side when you make those readings, and we don't think it was that low. We think it is lower than the left side, however.

DR. RIDE: Did that get fed back to Thiokol, that you saw readings that low?

MR. LAMBERTH: Sally, I'm not sure. The requirement that we had when we go out with the ice team, as Bob said, the requirement we give the ice team is to assess the pad conditions. At this particular time we were looking very heavy at the ice on the facility, the ice in the holding troughs underneath the SRB, and any other ice on the facility, as well as ice on the vehicle.

And like I said, the facility and the holding troughs had water underneath. That was our big concern. We did talk about the temperature we read in the holding troughs, ten degrees. To my knowledge, the temperatures as we read off the SRB's were not discussed at that time.

We did discuss the readings we got in the




troughs, though.

DR. COVERT: Do the troughs see the night sky?

MR. LAMBERTH: We were reading temperatures in the trough of about ten degrees, and we were taking those basically from the same -

DR. COVERT: But the trough looks up at the night sky and it's out of the wind, so it is essentially a calm, good radiation reading?

MR. LAMBERTH: Yes. We had a ten mile an hour wind, the way we were taking the readings.

MR. SUTTER: Would the wind affect the temperature of one versus the other?

MR. LAMBERTH: The wind, by all of our analysis, the wind would be the effect that you get from the sky radiation, yes, sir.

CHAIRMAN ROGERS: Just because we are in closed session, I don't want to be unpleasant, but - and maybe I am being unpleasant, but it would seem to me that if the temperature at that time you've got down there was in the low 20's at 2:00 o'clock in the morning and it had been in [427] the low 20's for approximately 11 hours, and everybody knew that that would probably have some adverse effect and there were some limits of some kind about that, why that wasn't a matter of major





I can see why your team that was primarily concerned about ice and damage to the orbiter and the facility, whether the water faucet was working and that stuff - but I would think that that would have been a major concern to everybody.

And it would be helpful in this closed session, because you're going to be struck with it in public. What was it?

MR. ALDRICH: Could I speak to that? As I mentioned, I reviewed the details of the situation with respect to the orbiter and the physical ice on the facility. At no time during this period was I aware of a concern for the temperature of the SRB within the ranges as we had from the weather forecaster. It was not known to me as a constraint on the performance of the solid rocket booster as a system or any of its elements.

GENERAL KUTYNA: But, Bob Crippen, you said that there were no criteria on temperature on any of the solids, and yet in previous testimony we heard somebody say don't launch outside of 40 to 90 degrees.

MR. CRIPPEN: I'm saying there's no requirement for us to go out and measure temperature, like with an IR gun on the solids, and play that back




against the criteria. Yes, there is a bulk temperature requirement on the solids.

GENERAL KUTYNA: But when you qual a system, be it an airplane or be it a spaceship or whatever, and you do qual it within certain temperature limits - there was no such qual done on this and no temperature limits that these solids were qual'ed for.

MR. REINARTZ: Stan Reinartz, Marshall Space Flight Center, Projects Manager for the propulsion element that we had at Marshall.

The qualification of the motor is, yes, as Larry Mulloy, project manager stated, it is for the mean bulk temperature of 40. That was considered in the forecast that was made the night before, and we have a plot for weather, temperature, in the various conditions we could see.

And that was calculated, and it was calculated to be in the 55 to 56 degree temperature range. And when we launched that, at the time we then launched, that was what we were still predicting, in the 55 to 56 temperature for the mean bulk.

GENERAL KUTYNA: So mean bulk was the only constraint you had temperature-wise?

MR. REINARTZ: That was the constraint that we had.




CHAIRMAN ROGERS: Do you mean you were operating under the prediction that it was going to be 55?

MR. REINARTZ: No, sir. There is in the total solid propellant, you have an enormous heat sink or mass, and during the course of the weather changes down here at the Cape that mass of the propellant changes very slowly over time. And the temperature that we had predicted, knowing the conditions that were coming in starting 48 hours ahead and then for our meeting, is we were predicting we would be at a mean bulk temperature of the 55 to 56 degree range.

We have had a previous launch that launched at 52 degrees mean bulk temperature on the previous launch, and so it was within our experience base that we had for launching the vehicle at that temperature.

[428] CHAIRMAN ROGERS: Put it another way, then, if the temperature was 20 below or 20 degrees for eleven hours, it was thought that that would not affect the solid fuel in the booster to reduce it below 56?

MR. REINARTZ: That is correct, sir.

CHAIRMAN ROGERS: But there was no way to measure that, and so you did it on a projection basis?

MR. REINARTZ: It is analytical, based upon some early data that we had done on the propellants at




Wasatch, where we had some instruments that measured internal temperature, and then it was done from calculations based upon those types of measurements.

CHAIRMAN ROGERS: How low would the temperature have had to be before it would have been a problem in your thinking, and how long? Suppose it was eleven hours of zero temperature?

MR. REINARTZ: It would have had to have been for several days of time.

MR. HARDY: If I could help, in the model that we have, as Stan said, the model was calibrated from instrumentation that we had on these propellants early in the program, and also from the Minuteman program, which uses essentially the same propellant.

But the model was, say, in effect it follows ambient temperature of about 20 days. That is how big the thermal mass is, the mean bulk temperature. And so to get the temperature of the propellant down to 25 degrees - and this is rough - you would have to cold soak it for, let me say, 15 to 18 or 20 days, in order to get the temperature down that low.

CHAIRMAN ROGERS: That's another way of saying that as far as, based upon the previous experience, as far as you were concerned, that the coldness of the weather really wasn't of concern as far as the solid




fuel boosters are concerned.

MR. HARDY: Absolutely correct.

DR. COVERT: George, I have a question related to mean bulk temperature, and I understand what you're getting at here. But there's also a problem of temperature gradients, and depending upon the degree of rapidity of the change of the temperature, you could have a tolerable mean bulk temperature, but you could have fairly high temperature gradience which could give rise to anomalous effects that you've had previously.

Have you any estimate of the rate of temperature gradient?

MR. HARDY: Yes, we have analytically calculated gradient across the range for 51-L. I don't have those numbers, but this afternoon I can tell you what that was.

DR. COVERT: And I would like to see also the difference in temperature gradience between the middle of the panel and the neighborhood of the rings for where the field joints are made, because of the difference in thermal mass of the steel. Can you get that for me?

MR. HARDY: I will do that.

Let me just mention one other thing. The primary concern - And I'm sure many of you know this - on bulk temperatures in solid propellant is the strain




of the propellant and the potential for cracking the propellant.

[429] DR. FEYNMAN: Why is the mean an appropriate number, rather than the differences or the lowest values? Where it cracks isn't very important. The mean only tells you it doesn't crack on the average, where it could crack where it's lowest, right?

MR. HARDY: The effect of the temperature in terms of cracking would obviously be where it is lowest. The highest strains in the propellant are near the bore of the propellant. The bore of the propellant in where the mandril is. You have a mandril with the propellant around it. The highest strains are typically around the bore of the propellant.

Now, the highest strains that propellants will see in the motor are when the propellant is cured. There's a fairly rapid cooldown of the propellant under transportation conditions or under storage conditions. When you ignite the motor, then the pressure is uniformly inside the bore, pushing against the propellant. Then of course the effect of temperature strain rates at that time are much less.

DR. FEYNMAN: You mean cracking deeper in would be closed by the pressure, presumably, so when the burning got down to there it wouldn't penetrate the




cracks and the rate of burning would be uniform, even though the material may have in fact been cracked and crumbled near the outside?

That wouldn't, presumably, be of much importance because the pressure holds it together.

MR. HARDY: That is correct. And if I could just add one other thing, one other bit of information, in any sort of failure analysis on a solid rocket motor, looking for propellant problems, propellant cracking or anything of that nature, you look in the pressure-time trace.

And if you crack propellants and increase the burning surface any significant amount at all, that will show up readily in the pressure-time trace.

VICE CHAIRMAN ARMSTRONG: Are there concerns other than cracking with the lower temperature?

MR. HARDY: Not with regards to the propellant.

DR. COVERT: Are you saying, George, no anomalous pressure-time behavior in these boosters?

MR. HARDY: We will talk about those events. There are none which we can associate with the anomalous propellant parameter.

MR. WALKER: One other question. Then there is no temperature specification or requirement on the




steel case? Presumably the steel case follows the ambient temperatures, although in this case it was lower than the ambient in some cases.

MR. LAMBERTH: The requirement is for an operating motor at 40 degrees, the operating motor.

MR. WALKER: But the steel case is going to be colder than that.

MR. LAMBERTH: But I don't know - and we will be furnishing at the time we talk about the detailed weather discussion, we will go into the entire set of qualification data and requirements, and each piece that goes with that for the environment it is to survive and what qualification tests were done to assure that.

MR. WALKER: But what I was asking, is there a specific requirement on the temperature of the steel case, as opposed to the bulk temperature?

MR. LAMBERTH: To my knowledge, there is not a specific requirement on the steel case.

MR. WALKER: So ever though you actually measured this temperature with the pyrometer, nothing was done with that data?

[430] MR. LAMBERTH: Yes, that is a correct statement. There is no requirement to take measurement or to act on that data.

DR. RIDE: Let me ask that another way. I




guess the question would really be what launch commit criteria there are related to cold temperature.

MR. ALDRICH: I was just trying to fit that in if I got the floor again, Mr. Chairman and Sally. The launch commit criteria we have for cold temperature is to launch at an ambient outside temperature at launch time of 31 degrees or greater.

Now, the prediction was for that case to be greater than that, and that in fact is how the data turned out. There are no more definitive or solid element-unique criteria specific in that.

DR. RIDE: So the assumption is that, back when the solid rocket boosters were, to pick an example, were qualified and built and certified for launch on the shuttle flight, they had to prove that if the ambient temperature was 31 degrees, all parts of the solid rocket were go for launch?

MR. ALDRICH: That would be implied, and it has been for a series of launches.

CHAIRMAN ROGERS: Without going through this whole discussion, because I know we're coming to it later, but did Thiokol - why did Thiokol advise against it the night before because of the weather, as I understood it? At least I gather that they did.

MR. LAMBERTH: Mr. Chairman, their concern




that they raised at that time - and we will give you a full discussion of that, and Thiokol will also explain their position. But it was related to the O-rings, was the only point for consideration that they raised in that discussion on the potential lower temperature.

CHAIRMAN ROGERS: Of the O-rings?

MR. LAMBERTH: Of the O-rings, and the possibility that you might have increased erosion due to the lower temperature.

CHAIRMAN ROGERS: Well, we will come to that later.

MR. WALKER: But there is no such written requirement? That is just something they brought up and were concerned about, and it is not written down and it is not a checklist item?

MR. LAMBERTH: That was not a checklist item against the launch procedure.


MR. KOHRS: I think I will get off the pre-launch and move on to the ascent time line.

GENERAL KUTYNA: Before you do, one more question on launch. What were these delays costing you in terms of either future mission processing or experiments flown on this mission? Were we losing any experiments because of these delays?




MR. KOHRS: No, sir. We had a three-hour launch window that we had signed up with both the TDRS projects and with the Spartan Halley projects, and there was no constraint beyond the three hours.

GENERAL KUTYNA: So you weren't going to miss Halley's Comet by going beyond the 28th?

MR. KOHRS: No, sir.


MR. KOHRS: The next chart, which is starting the time line for ascent, and let me say a few words.

[431] (Viewgraph.) [Ref. 2/13-6]

I've listed four pages here. To start at the beginning, the main engine start command, which is 6.6 seconds before the SRB command. And I have listed the events in the center of the page, and I will try to make sure I cover all the acronyms. And I have listed over in the right-hand column in "remarks" whether the data was nominal, and the nominal data as we read it is on our telemetry data that comes down.

And then our other data which talks about this anomaly is data that we have recreated from our cameras, different camera locations. And here I've just listed camera number 60, camera number 207. Charlie Stevenson will talk next and show you those cameras and more details on their locations.




What I will do later on, then I will bring up some charts on the right that show you what downlink or telemetry data we use to pick off these data points. And the camera data data points were picked off really from time tags and the count of frames in the cameras.

We'd look - like I said, the main engines, the SSE start command is the nominal 6.6 seconds before SRB. At about 3.7 seconds into that, the engines build up to 100 percent of rated thrust. There is a series of internal checks that say, we're ready to launch, all automatic within the computer.

And then the zero point which I've listed here, which was 11:38.0.010, is the best estimate of the SRB ignition command.

Now, at the top of the chart I've labeled this data as of 2/12/86, which is yesterday, and we're still refining the detailed times between us and all the other projects. We are within a few milliseconds on these time tags. You may see some data later that is maybe a little bit different here.

DR. RIDE: Was there anything anomalous at all within the main engines?

MR. KOHRS: No. Let me say, all of our engine data from post-flight reconstruction, all of our orbiter data from post-flight reconstruction, we don't see any




anomalies to date.

MR. MOORE: I would qualify that to say to date. It has not been checked off the list and say it has been exonerated. It is still going on. But as of now, we see nothing anomalous in that data.

MR. RUMMEL: May I ask, do the computers check this in some way or another?

MR. KOHRS: Yes, sir. During the engine startup, the engines have their own managing controller that has a series of red line criteria built in that it has to meet certain gates, of valve openings, throttle levels, and time levels and temperature levels to proceed to launch.

If we don't pass those gates during the 6.6 seconds, we call those internal red lines to the computer. We will get what we call an automatic cutoff.

MR. RUMMEL: Let me ask it differently. Is there redundancy in the computer recording setup?

MR. KOHRS: Yes, sir.

MR. RUMMEL: Have you checked one against the other?

MR. KOHRS: We do have criteria that our redundancy has to be there at liftoff. So we have, like if you have two measurements up until the time of SRB




ignition command, you have to have redundancy in our critical measurements.

[432] The first movement was plus .05 seconds. The key thing here, you will see on the pictures at .445 seconds, is our first evidence of black smoke from the right-hand SRB near the aft field joint, and we will show you that coming up.

MR. SUTTER: Could you show where that is on that model?

MR. KOHRS: We think it was back in this quadrant over here.

MR. STEVENSON: That's right.

MR. WALKER: Could you point out the lower field joint?

MR. KOHRS: That's right here, this white line.

MR. LEE: This is Jack Lee. You might point out from the camera angles, from the photography we have, it's not obvious where it comes from. It is emanating between the right-hand SRB and the external tank.

MR. KOHRS: You see it right in this area in the film.

DR. COVERT: I assume you've gone back and looked at a lot of other films since then of other,




earlier launches, and this is the only case that you've seen this black smoke?

MR. LEE: Yes, that's true.

DR. COVERT: Thank you.

MR. WALKER: Are there indeed over 200 cameras that you use?

MR. KOHRS: I think I've looked at about 82 or so films from this flight. There may be more, plus you had the TV cameras.

MR. WALKER: But the film cameras we're talking about here?

MR. KOHRS: These are 16 millimeter here, and we also have 70 millimeter.

DR. COVERT: Yes. Do you really know the framing rate to a millisecond?

MR. KOHRS: Yes. The 70 millimeter has a time tag on it. The 16 millimeter we're having a little bit of difficulty, and that is why you see some differences in persons looking at the film.

These two events you will see were abnormal. The roll maneuver was at 7.7 seconds, where the vehicle rolls. That was nominal.

If I could have the next chart up.

(Viewgraph.) [Ref. 2/13-7]

GENERAL KUTYNA: At liftoff do you measure




loads on the holddown bolts?

MR. KOHRS: Right.

GENERAL KUTYNA: Was there anything unusual in that?

MR. KOHRS: To date, we're still developing that data and going back through what we call our liftoff load reconstruction, and that still is about a week away, a detailed analysis.

Here again I will just show you - and it is in your handouts, and I know you can't read that chart. But in the right-hand upper corner in your handout will be a time that is tagged here. And the only reason I'm pointing this out - I'm sorry, right here, 7.7 seconds. The only reason I point this out is this is where we pick off the start of the roll maneuver, is our time tag.

And I'm not going to dwell on the details of that chart, but that particular one is the roll rate gyro on the vehicle, and it is normal as predicted.

The next chart.

(Viewgraph.) [Ref. 2/13-8]

[433] The next event is - let me talk about this one. This is an approximate. The last visual indication of the black smoke coming out of this area is in the 12 to 13 second time frame, and that is still




under study with different people looking at the film and looking at it with different cameras. This time I suspect we'll refine probably within the next week to get that pinned down.

The throttle maneuvers, and here it is picked off with the chamber pressure movements. This is chamber pressure of the engines, and it just shows you our nominal chamber or SSME throttle setting. We lift off at 100 percent, we throttle up to 104. As we get into our max Q area, we throttle down here to 94 percent for ten seconds, and then down to 65 percent, and then back up to the 104 percent, and fly at 104 percent for the remainder of the mission.

DR. FEYNMAN: What is measured on the vertical axis?

MR. KOHRS: That's chamber pressure, engine chamber. I'm sorry, it is chamber pressure that has been converted to throttle setting. But the reading is really PC or chamber pressure.

DR. COVERT: Which one of the engines is that?

MR. KOHRS: This particular engine is main engine 2, and they are all the same, though.

DR. FEYNMAN: In making this conversion, is it a simple mathematical formula or is it some kind of




guess? And the reason I ask is that the lines are extremely straight and flat, and I wonder what you measured so accurately that didn't have any wiggles in it.

MR. KOHRS: These are commands that we are measuring, but it is based on the PC measurements.

DR. FEYNMAN: PC measurements are measurements of chamber pressure, measurements of a physical quantity, and there are all kinds of noises and vibrations, and it has been extracted from this?

MR. KOHRS: It has been smoothed out.

DR. COVERT: Well, there's also the zero suppress.

MR. HOTZ: Do the solid motors change thrust in synchronization with the throttling back of the main engines?

MR. KOHRS: The solid rocket motor is cast to a specific burn rate versus time, or thrust versus time.

MR. HOTZ: But does that change during the course of this?

MR. KOHRS: It does change during time, and I think last week we did show you, I think. Jud Lovingood did show you a thrust versus time for the solid rocket boosters.




MR. HOTZ: There was some other testimony, though, that it didn't change.

MR. KOHRS: In my terminology, the confusion - there were some people thought there was some way to command to change. That is cast into the motor.

MR. HOTZ: No, I understand that. But it is a change which is roughly similar to your throttling back of your main engines?

MR. KOHRS: Yes. If you superimpose the throttle back of the SRBs, it is throttling down in the same time frame the chamber pressure is going from 900 to roughly probably 500 or 600.

MR. HOTZ: The curve that he gave us showed that, down and up.

MR. RUMMEL: On the burn rate inside the solid rockets, for clarification, I take it the motor burns longitudinally from the aft end forward, and then outward?

[434] MR. KOHRS: No, it burns radially, uniformly throughout the length.

MR. RUMMEL: So the exposure of the hottest gases would be toward the end of the burn, then, on the various joints, is that correct?


MR. RUMMEL: Well, is it correct to assume




that the exposure of the seams toward the nozzle are exposed at the same point in time as the rest of the seams or earlier?

MR. KOHRS: I would have to ask George Hardy, but I think it is uniform, I believe. Now, George will have to give you the specific answer.

MR. LEE: That is accounted for in the insulation inside the case. There's a different thickness in the aft sections, if that is the answer to your question.

MR. RUMMEL: So you take that into account by varying the insulation thickness?

MR. LEE: Yes.

MR. RUMMEL: I see. Thank you.

MR. SUTTER: I assume you are studying where did the black smoke come from?

MR. KOHRS: Right, and we're going to show you those photos, and that is still being studied. And we are also using the best enhancement techniques we have to try to pinpoint that.

MR. SUTTER: But what would make black smoke?

MR. KOHRS: That is what we're still trying to determine. There is grease in this area, but there has to be some ignition source or some temperature source for that to happen.




(Viewgraph.) [Ref. 2/13-9]

The next chart will drop you down to the roll maneuver, and here again I'm just showing you the data we picked off of the gyro. And this event here again is completed here at 21 seconds.

I showed you on the previous chart the throttle-down to 65 percent. At around 40 seconds - during ascent we get our normal actuator movement responding to wind,

We saw a little bit more activity during that area, well within our experience base and not any concern with the loads that were created within that time frame.

The next chart, please.

(Viewgraph.) [Ref. 2/13-10]

Oh, back up one. I need to finish.

(Viewgraph.) [Ref. 2/13-9]

We did the throttle-up which I talked about, and then at 58.7 seconds was our first indication of smoke from the minus Z side, in this area of the right-hand SRB, just forward of this, we think just forward of this aft ring.

CHAIRMAN ROGERS: I can't quite see your pointer. Did the smoke come from the same place?




MR. KOHRS: The same area, the area we are seeing the smoke up here on the films and then later at the 57 time in this area here.

CHAIRMAN ROGERS: And you're pointing to the right booster?


MR. HOTZ: Is this a different colored smoke you're seeing now?

[435] MR. KOHRS: Here you're really approaching the flame and the hot spot in this area. Here you will see in the film that this is definitely what I call black smoke. I think you just need to see that in the upcoming film.

GENERAL KUTYNA: So this thing at 58 seconds should not be called smoke?

MR. KOHRS: Well, it's the first indication. In the next slide I'll put up, it shows how it progresses.

MR. CRIPPEN: But that was not black smoke you saw at 58?

MR. KOHRS: It was smoke; it was not black smoke.

The next chart, please.

(Viewgraph.) [Ref. 2/13-10]

At about 59 seconds, we hit our max dynamic pressure. And I think I should have a chart 15 on the right.




(Viewgraph.) [Ref. 2/13-11]

Here is just a plot of recreated max dynamic pressure. The NAV derived on top is just a reference based upon the monthly mean winds. The solid line is the max pressure in pounds per square foot versus elapsed time.

And you see here we approach roughly 720 at around 59 to 60 seconds, and we have tagged it here from a detailed look at 59 seconds. At 59-1/4 you get a well-defined, intense plume, which you will see on the camera, and then the next slide will show you at 60.1 you start to get a chamber pressure divergence from the right-hand to the left-hand SRB.

The next slide, please.

(Viewgraph.) [Ref. 2/13-12]

Let me back up one. While I have this one up, I was just going to show you what the wind profile was for that day, reconstructed. The point to make on this chart is that at about 60 seconds we were also getting this change, high rapid change in the wind direction, which is in our normal design base, experience base, but this happened to occur around the same time as you see the build-up of this smoke area and plume area.

MR. WAITE: Also, max Q.

MR. KOHRS: Max Q was right around 59 seconds,




right here. And the thing that makes max Q right here is that the vehicle is flying and this actually is a headwind to the vehicle's nominal flight path. The vehicle is trying to fly up against this wind and here, as it sees this apparent headwind to what it's trying to fly, the headwind is going to up the max dynamic pressure.

And that is really what you see on that chart I had previously. You see that hump in the change of the dynamic pressure, which is just reacting to that wind.

GENERAL KUTYNA: That is all happening, that zig-zag is happening, after you had a problem? Is that right?

MR. KOHRS: Apparently it occurred right after the first 59 seconds. This is the in-plane wind. The next chart just shows the out-of-plane component of that same velocity plot.

The next chart -

(Viewgraph.) [Ref. 2/13-13]

- which is at 60.164, and what is plotted here is the left-hand solid rocket booster and the right-hand solid rocket booster chamber pressure. And, as we discussed earlier, the chamber pressure in this time frame as you're in the SRM bucket gets down to the


[436] 826


600 psi pressure level.

This difference here is not abnormal. Where you really see the right-hand SRB is it starts diverging out here, and this point is the point we picked for the 60.164 time frame.

Other people, just for background, you may see a little different time, may pick this point or that point, and you will get a few tenths of a second time difference.

MR. WAITE: Is that monitor real time?

MR. KOHRS: This data is sent down real time. It is run through our mission control center. It's processed, displayed to the flight control team at one sample per second. The data you see here is data that is recorded, that is coming down and then played back and analyzed at the higher sample rates.

I think this sample rate is probably up at the 100 samples per second. But in terms of what the person on the flight control team sees on the ground on launch day, it is displayed to them at one sample per second, and the data through the processing time is in the three- to four-second time delay, in that time frame.

DR. COVERT: And this thing really can read two psi out of 1,000?





MR. WAITE: How is that chamber pressure derived?

MR. KOHRS: We actually have on each booster two or three - three chamber pressure measurements that are fed directly from the SRBs over to the orbiter and then down.

MR. WAITE: Is that a direct pressure measurement or a strain gauge?

MR. KOHRS: It's a direct pressure measurement, a transducer.

DR. FEYNMAN: What is the horizontal scale? I can't read the numbers. It goes from 55 to zero?

MR. KOHRS: That is time, sir. If you slide this chart down a little bit - to put this in English, down a little bit further, slide that right chart down if you can.

Up here I have put the time. 60.164 is this point right here.


MR. KOHRS: We didn't have time to go back and put the right readable plots on there.

MR. WAITE: When do you think the control room first saw the pressure change, four seconds after that?

MR. KOHRS: I don't really think, in terms of the control room display, they - and I will have to check this - ever saw a pressure




change. By the time they recognized that - they really didn't see it until this data was played back and looked at in detail. This type of pressure change was probably not recognized.

The next chart, please.

(Viewgraph.) [Ref. 2/13-14]

During this time frame, which is also the time we're reacting to the wind load, the max dynamic pressure, and we've got now a plume, the elevons and the gimbals are moving to react. And all we're showing here in this sequence of telemetry data from 60.2 seconds is that we've got elevon movement and actuator movement.

And I can go through these charts pretty quick. The charts on the right - or on the left, are just showing you these time points and how we picked them up. And you can see here a spike [437] and here a differential pressure. But you've got to look at a lot of missions to pick out that this is a change in differential pressure, this little spike right here.

The next chart, please.

(Viewgraph.) [Ref. 2/13-15]




MR. KOHRS: This timeframe is when we started the SSME pitch variations, and you would expect the SSME to come down this line right here (indicating), and you've got a variation here which says that the vehicle is reacting to some external forces. The next chart, please.

(Viewgraph.) [Ref. 2/13-16]

DR. COVERT: Could I ask a question on the previous chart that you just had? If you look at that mean slope, and then it seems to pick up the mean slope again, so that this is probably a wind shear, and it is not probably any other anomaly?

MR. KOHRS: That, sir, is what we have to sort out, because at the same time this event is occurring, you've got this wind change. You've got a normal reaction; then we've got an external force. And what we have to do is try to separate out those two variables.

The other thing I would mention here is this wind data is based on balloon release that is in this case based upon a balloon that was released about ten minutes after launch, but it in itself is not totally accurate. So you can also have a different wind environment than we actually measured.

DR. COVERT: That is why I asked you before if you had watched the plume spreading and worked backwards.




MR. KOHRS: We are in the process of doing that.

DR. FEYNMAN: What does "pitch" mean?

MR. KOHRS: "Pitch" is the angle from the horizontal you are changing out of plane and looking forward at the pitch plane, and the yaw plane is to the right or left.

The next chart, in the center - well, let me keep that one here. We also saw some other deviations.

DR. COVERT: I guess I really want to go back to that other chart, please.

MR. KOHRS: Could you go back to that previous chart, number 16, on the left?

(Viewgraph.) [Ref. 2/13-16]

DR. COVERT: Now my question, the real thrust of my question is: Is that sort of gradual slope down there, ignoring for a moment that little thing, is that pretty much normal?

MR. KOHRS: It is pretty much normal. The vehicle is normally trying to control through the CG as we are depleting propellant. So you're normally going to get some movement of the actuators to keep this thing trimmed out.

DR. COVERT: But if we sort of put an average on this, the points that are labeled 07-001 are within a




fraction of a degree of where they would have been normally?

MR. KOHRS: Right.

DR. COVERT: Thank you.

MR. KOHRS: The next chart on the left, and here again let me pick up.

(Viewgraph.) [Ref. 2/13-17]

The next chart on the left - and I need a new chart in the middle, chart 9 in the mid

(Viewgraph.) [Ref. 2/13-17]

[438] Here at about 72 seconds, 72.141 and 72.661, looking at the gyros we're seeing a rapid change acceleration, which means we're getting a side force on the vehicle. Y acceleration, this is the Y direction out the side of the vehicle, so the vehicle is moving on one side in this case, as compared to the other. This is at 72 seconds. At 72.4 - we also had a tracking data relay system on board, which has its own gyros.

That data was telemetered to the ground. We have gone back and looked at that data, and it confirms that it matches the gyro data that we were seeing in the orbiter. And there is nothing anomalous with the TDRS. It just is another data source that says that it matches, and we happened to lose this data at 72.4 seconds.




I pointed out the lateral Y acceleration. Here we see the MPS, which is the main propulsion system, LOX, L02, and hydrogen inlet pressures drop slightly.

DR. RIDE: Could you go back to the 66 seconds? Were you going to say anything about the LH2 pressure?

MR. KOHRS: I wasn't going to say anything, Sally, other than we see a slight drop in the LH2 pressure. I did not put a chart in this. Well, I guess I did put a chart. It's really 66.484. It's really figure 23 that shows that deviation.

(Viewgraph.) [Ref. 2/13-18]

And if I could, I could put chart - here it is over here. By the way, we have three LH pressure transducers that drive three, or provide information to three flow control valves in the orbiter. What you are seeing here is (ullage) they track each other pretty well, and then you get down to this point and you start to see a deviation. And this one is SSME engine number one, and these are engines two and three, which are still tracking each other.

DR. FEYNMAN: By ullage pressure do you mean the pressure above the fuel, or the oxidizer?

MR. KOHRS: Yes, sir.

DR. COVERT: I guess, sir, I don't want to




argue with you, because you know more about this than I do, but if I just take my pen here and try to see what the discrepancy in these two lines are, the difference persists pretty much across the whole chart. It looks closer because of the steep gradient, but if you just sort of measure and count the number of dots involved - -

MR. KOHRS: These are very subtle changes, and what we have looked for are anything that is abnormal. We may find in later analysis that you are indeed right, and this is normal.

DR. COVERT: I'm not saying it is normal. What I am objecting to is that your arrow is located there, where I could locate that arrow anywhere on this chart.

MR. KOHRS: I would accept that.

MR. ACHESON: Is your lateral movement in the direction you would expect it to be if it were driven by a combustion leak back there?

MR. KOHRS: Tom Moser I think will have some charts later that will take this data and build you a failure scenario based upon this data. I'm trying to present the data in a cut at the time line of these major events.

MR. MOORE: Well, really, the answer to your question is, yes.




(Viewgraph.) [Ref. 2/13-19]

[439] MR. KOHRS: Following on this chart is the TDRS data. We had the chamber pressure drop which showed up on the other chart in this timeframe. If I could have the other chart, I think it would just - I'm sorry, it is not the next chart. These last ones we essentially had based all of our data and timing on the camera locations. And you will see these cameras coming up. Chart 10 in the center.

(Viewgraph.) [Ref. 2/13-20]

Turbine temperature. That is just the pitch rate divergence. The other thing that we found - and this data is a couple of days old - as we looked further at our down list of data, is that the main engines, the SSMEs, were approaching their redline limits for the high pressure fuel turbopump. The redline limit I think in this case is about 1960 degrees.

DR. COVERT: This is essentially the turbine temperature?

MR. KOHRS: High pressure fuel turbopump discharge temperature. That is what the HPFT stands for, high pressure fuel turbopump redline temperature. And then later where we think - and this data is still being reviewed at this timeframe - we actually had a shutdown of SSME engine number one. At 73.605 was our last validated data. And if I had the next chart, I




could show you - and that is a very subtle change. I need chart 29 up on the right.

DR. COVERT: Is the number one engine on the right?

MR. KOHRS: That's the top one. Here again are the RCS jets, which are the reaction control system jets, which are located up here on the vehicle, aren't firing during this timeframe. They do have pressure measurements. So when we do fire them, we see the pressure in the chamber. And the only thing that is happening here is normally during ascent, the chamber pressure should just be dropping from 14.7 atmospheric down to essentially a zero pressure.

(Viewgraph.) [Ref. 2/13-21]

Now in this timeframe, which is noted over here, you should see just before the loss of data we can see a buildup that says that it was seeing some change in pressure up in this area, probably from the plume or the explosion, and that was our last validated data. And a few milliseconds later was our last data frame. And then on the pictures at 76.425, we saw the drogue chute coming out of the right-hand SRB, and you will see that. And then at 109 seconds, the righthand SRB range destruct system destructed that booster. And then at 110.2 seconds, the range safety system destructed the




left-hand booster.

MR. CRIPPEN: Dick, just so people don't think there were anomalies. You were talking about the main engine temps getting high. That was explainable.

MR. KOHRS: That was a reaction to the event. We feel that that was the reaction that we were loosing LOX or hydrogen to the pump, and it was overtemping.

GEN. KUTYNA: Where were those boosters at impact?

COLONEL LINDSAY: Their normal impact area is about 140 knots or about 90 miles offshore. So a normal flight would carry them about 140 knots.

GEN. KUTYNA: Where were these going to go that caused you to blow them up?

COLONEL LINDSAY: I don't know. When the explosion occurred, all data was lost. The next set of information we have was visual from the videos that we displayed, and you were able to see, depending on which video you were looking at, one propulsive SRB coming out of the cloud, and later you could see on other screens, too, and displaying some erratic flight as far as we could see.

DR. COVERT: You could see some tumbling of the right-hand booster?

[440] COLONEL LINDSAY: I wouldn't call it "tumbling." It was fishtailing.




DR. COVERT: Did you have enough time to actually see it come back? Or just veering off?

COLONEL LINDSAY: No, you could see it do a turn.

GEN. KUTYNA: I think there was some insinuations that if we hadn't blown those things up we would have had wonderful data to retrieve.

COLONEL LINDSAY: I doubt that. One motor, the one that you will see later, the right motor that we have the best data on was still climbing at 122,000 feet when it was destroyed. Estimates on its impact would be very significant damage, maybe fracturing when it impacted on the water, and, if there was propellant left in it, probably detonation of some percentage of the explosive content.

MR. MOORE: Don, we do have a detailed presentation on range safety, if the committee would like to look at it. We are planning to cover some of that.

GEN. KUTYNA: There was an article in The Post that, gee, if the Air Force hadn't destroyed these things, we would have had wonderful data.

MR. KOHRS: This was the last timeline chart. What I put together on my last chart is kind of an




observation chart of this ascent timeline, which is on chart 30. But basically, as I said earlier, the orbiter data and the main engine data, up until the start of this event, all appeared nominal. And the areas that we are concentrating on in our further analysis are the photoanalysis of the SRB and the external tank.

DR. FEYNMAN: You say "nominal" up until when?

MR. KOHRS: Up until we started to get these divergences. That was about 59 seconds, in that timeframe. And the last chart, chart 30, kind of summarizes that.

(Viewgraph.) [Ref. 2/13-22]

The only thing, we talked earlier about the angle of attack profile, critiques this deviation, based on this wind shear we had, but when we try to reconstruct it, we cannot totally reconstruct it. We have got some external force which undoubtedly is this plume, and we've got some uncertainty in our wind profile. That is what we will be refining within the next weeks to give you a better backout of the effect.

And the other point is that our wind load indicators, which are the measure of the stress that the vehicle is seeing during ascent, which we have done for these load indicator routines during all our flights, and in this particular flight our highest




indicator, which happened to be a wing indicator in this case, was 87 percent. And the SRB indicators, which are really the indicators that we developed back where the tank is tied to the vehicle, we were down in the 30 percent of their limit load capability as measured against their load capability.

MR. RUMMEL: Again, Are the limit loads the maximum computed applied loads? Is that correct? As opposed to design loads, which would then have the load factor applied? Can you just clarify what the 30 percent is of here?

MR. KOHRS: It is 30 percent of a factor of safety of 1.4. That's the way I would say it.

MR. RUMMEL: Are those factors applied to what we would normally call the design loads? That is, the actual load plus a load factor? I notice there is a load factor of 3 someplace.

[441] MR. KOHRS: In some cases - and, George, you could help me on the SRB on the load factor.

MR. HARDY: I'm not sure I understand the question.

MR. RUMMEL: Well, I'm trying to understand what these percentages are. Is it the design load, the maximum load? Or, is it what is called the applied load? Or is it a limit load? What is it?




MR. HARDY: As best I recall, it is the design load.

MR. RUMMEL: So you say it is of the computed maximum load to which is applied the load factor, to which then is applied the safety factor which is 1.4. Is that correct?

MR. HARDY: I believe that is correct.

MR. RUMMEL: Thank you.

GEN. KUTYNA: Jess, 87 percent shouldn't give you any problems or concern. You've been there before.

MR. KOHRS: That is well within our base.

MR. MOORE: We've been above 87 percent many times.

MR. KOHRS: This actual trajectory for that day was what we call a benign trajectory in a load sense.

Mr. Chairman, that's all the charts I had.

CHAIRMAN ROGERS: You were mentioning you would have some of this data completed in two weeks. Is that about what you are estimating?

MR. KOHRS: Well, here again what we call our ascent trajectory reconstruction, and part of that takes you back to the liftoff loads and gets you all the way through the completion of the events, we should have a pretty good, what I call a preliminary cut, in the next




couple of weeks. The final cut is probably in a month's timeframe to reconstruct all of this.

CHAIRMAN ROGERS: Does that include everything? In other words, will all of the collection of material and data and photographs be completed within a month?

MR. KOHRS: I can't answer to photographic. I'm talking about the flight telemetry data.

CHAIRMAN ROGERS: I'm not trying to hold you to it.

MR. MOORE: We're going to show you tomorrow, Mr. Chairman, what we think the analytical and testing process associated with our task force is going to take in terms of time. I think from a trajectory reconstruction and so forth, we hope to be able to get everybody agreed and in sync on the details of what happened sometime within the next couple of weeks.

I think with respect to the photography data, it depends upon what we find in that data. I mean, it may take us several additional weeks once we have identified an area to go back and get the best experts in this country to go and take a look at those photographs, enhance them and do digital analysis on the photographs. So that is kind of a to-be-determined with respect to the photographic data.

With respect to the data of the testing and




trying to re-create the set of circumstances on this thing, that will take a fairly long time.

CHAIRMAN ROGERS: I wasn't asking about that. I was asking about the analysis of the telemetry.

MR. MOORE: I think we are in what I would say, and anybody on our team can comment on it, I think we are in reasonable agreement about the major sequence of events. We are probably still off in terms of the precise times by a few-tenths of a second, or milliseconds, and so [442] forth, which we have not exactly pinned down yet. And based upon Dick's assessment, a couple of weeks is probably a reasonable time to expect us to be in fairly good agreement in terms of a timeline.

CHAIRMAN ROGERS: As you may know, I am going to have to testify Tuesday before the Senate Committee, and it would be helpful if I could make some general comments about it, to say that our review with you -

MR. MOORE: I'm going to be there, as well.

GEN. KUTYNA: Jess, I asked the question about liftoff loads because I've gotten through the back channel that there were some. You're not going to have that data for a few weeks, but do you have any preliminary that there might have been some liftoff loads that were unusual?




MR. MOORE: I will ask my Cape friends or Marshall friends, and so forth. I have not seen any done at this point in time.

MR. HARDY: We don't have the liftoff loads totally reconstructed. We're very interested in those loads, and we are working with Dick and his people to reconstruct those. I believe that that is somewhere in the neighborhood of a week or so away.

GEN. KUTYNA: But how about first-look?

MR. KOHRS: We have not seen anything. There are a few things that the guys are doubletracking to make sure that they've got the right timing, and the liftoff loads are a function of the liftoff time. As the vehicle bends over and is coming back, essentially we are minimizing the loads at liftoff, and there is some disagreement on the actual liftoff time. I showed on my chart 6.6 seconds SSME start T-06.6 seconds later. The guys that have looked at the strain guage data to date, and have just started looking at this, are about .08 to maybe a tenth of a second in disagreement that they are still trying to resolve. And to say we've got a problem today would just be conjecture until we get that detailed analysis. But I've had that same input and guys are working on it with all the priority that can be put on it.




MR. MOORE: Where is that work going on? At JSC?

MR. KOHRS: At JSC in conjunction with Marshall.

MR. MOORE: We would be happy to provide the status of what we have right now, Don. GEN. KUTYNA: Well, Jess, what I'm saying, I don't want the Commission to be surprised that, oh, you didn't tell us something. Because there's word going around that, hey, there was something squirrely about the liftoff loads. So, for the record, you are looking at it. Maybe there was, maybe there wasn't?

MR. MOORE: I had not even heard that. So I think you are using words I haven't heard yet. MR. KOHRS: I personally did not get that until last night, but we are working on it.

DR. COVERT: Could I ask Dr. Williams a question, please? Walt, if I recall correctly, one way to get an increase on the turbine temperature on the high pressure fuel turbopump would be to reduce oxygen flow. Is that right?

MR. WILLIAMS: No. You reduce hydrogen, if you go with more oxygen and less fuel.

MR. CRIPPEN: Which is what we were showing.

DR. COVERT: I just want to be sure my memory of




that was correct.

[443] MR. ACHESON: I don't need a long presentation on this, but just a clarification. What is destroyed in this destruct case that is not destroyed in the normal flight termination of the boosters?

MR. MOORE: Are you familiar enough with the range safety, Dick? Maybe we could get George Hardy up here to clarify what we think is destructed when a range safety device is fired. George, why don't you go illustrate.

MR. ACHESON: But it did come down on the chute? Is that correct?

MR. MOORE: No. The drogue chute did come out, but it did not come down on the chute. Following that, the range safety destruct sent commands up to destruct the vehicle. So it did not come down on the chute.

MR. HARDY: Well, as you well know, the booster is built in what are referred to as the four field segments, and then we have a forward skirt, and then the frustum, which houses the recovery system. And if I could, I would take just a few seconds to tell you how the normal recovery works. In a normal recovery after separation the recovery system is armed, and then, after it times out during the fallback phase, the pyrotechnics would jettison the nose. That pulls the pilot chute out,




which employs a drogue chute. That is at roughly 16,000 feet. And at about 6,000 feet, we pyrotechnically jettison the frustum which allows then the drogue chute to pull out the main chutes and the booster falls back into the water impact. It stabilizes very quickly under the three clustered main chutes, and it falls back in tail-first.

The range safety destruct obviously for a normal flyback is not actuated at all. The range safety destruct system is a linear-shaped charge. It is configured to concentrate the jet of the explosion, and it covers a portion of this forward segment, and then the forward center section, we call it, and most of the aft center segment. It terminates, as I recall, about 18 to 20 inches above the field joint here, and it is not on the aft segment at all. It is designed such that under pressure it will simply open up the case. It opens up the case, and the pressure will drop, and you lose all propulsive capability.

MR. RUMMEL: Is there a notch in the case, or a seam of any kind?

MR. HARDY: No, sir. It has been qualified that it will fire through the full case thickness.

MR. CRIPPEN: George, excuse me. I think maybe there's one other point. Someone correct me if




I'm wrong. I think some people thought that if we had not destructed on the range safety system, that we perhaps would have gotten a normal separation sequence which would put the chutes out, and it would have deployed the SRBs in the water.

These SRBs tore off of the system, and consequently they never received the normal set sequence that they would need to activate the system. So in fact by shutting down the thrust, it may have kept them from going higher and falling further.

MR. ACHESON: Parts of the booster that are valuable for evidence examination after the fact would have been lost in the destruct mode?

MR. MOORE: Well, all of - the key element that we are after in this thing is the apparent leakage in the field joint down there, and we do not think that is destructed. We think that field joint was not impacted by range safety, and we have got some sonar data that says that we have located the righthand solid rocket booster, and so forth, which will be extremely valuable evidence to us in terms of going back and fitting some of these failure scenarios.

[444] We plan to talk to the Commission this afternoon about what we have located on the bottom, but we do think we have the righthand aft case segment




intact enough to allow us to get some physical evidence back from the recovery, which is of paramount importance.

CHAIRMAN ROGERS: On that point, in the NBC report we heard just as we got on the plane that there was an official of NASA that said that you were 95 percent certain of what the cause was. Was that just a leak from somewhere? Was that a newspaper rumor?

MR. MOORE: I would certainly categorize that as a newspaper rumor.

CHAIRMAN ROGERS: You heard it, I assume?

MR. MOORE: I did not hear it.

CHAIRMAN ROGERS: It was the lead story on NBC that said a high official of NASA - now I think I'm an expert on leaks.


CHAIRMAN ROGERS: I'm just asking, as far as you know it was not a high official?

MR. MOORE: No, sir. We stand on the statements we made the other day. We do not have any cause pinned down at this point in time.

CHAIRMAN ROGERS: I'm not talking about these kinds of leaks. I'm talking about newspaper leaks.


COLONEL LINDSAY: Let me add one thought on




the destruct mechanism on the solid rocket boosters. The linear-shaped charge merely opens the case. It is designed to penetrate the steel case, and then it opens like a clamshell to instantly vent and go to zero thrust, so there is no further propulsive power. And that last segment did not have, by design, the linear-shaped charge.

MR. SILVEIRA: By stopping the burning at that time, you probably stopped the hot gases if you had any leak there, so you probably preserved the damage in the state we would like to look at it, rather than damaging it any further. The range destruct was probably a help rather than a hindrance.

DR. COVERT: Well, it has a potential, but it may well, when it hits the water, break apart. I agree that it has that potential.

DR. FEYNMAN: How are these things made? If you wanted to put out a chute, do you have to have the signals received by a radio that is located somewhere else, and it is wired across? But if you want to destroy it, it has its own receiver? How does it work?

MR. SILVEIRA: The normal chute functioning - -

MR. HARDY: Well, I will talk to the chute functioning, and you might talk to the range safety. But as Bob Crippen mentioned, as an interlock to make sure that we don't get any separation during the boost phase, which would not be healthy, we require two signals from the orbiter, two independent signals, what we call fire one and fire two, and those are the signals to separate the booster. And until that has happened, we have an interlock such that there is no power on the recovery system. The recovery system has its own battery power, and there is no power on the recovery system at all. When separation signal is received, those two separate signals, the power is - the bus is powered up by the battery; the switch is closed, so that you've got bus power; and then it is a combination of timing, timing [445] circuits, and altitude detection from the barrel switch that's sequenced, in the remaining things that I just described in the recovery system.

The range safety system does have its own receiver.

DR. FEYNMAN: Located on?

MR. HARDY: It's located on the booster. There is one on this booster. There is one on this booster. But they are redundant. Let me take that back. They are redundant on this booster, and they're redundant on this booster, and they are also on the external tank. And they are crossstrapped, so that if you had any occasion for destruct with the vehicle




intact, a signal received from either one of two receivers here, or either one of two receivers here, or the one receiver here would effect destruct.

After the booster is away, it has its own battery-powered redundant receivers.

DR. FEYNMAN: Thank you.

MR. SILVEIRA: Don't forget the separation motor sequence two.

MR. HARDY: In a normal separation, when the solids - when the separation signal is received, it is received to fire an explosive bolt here (indicating), and an explosive bolt in each of the three struts here. Those are redundant signals. Each end of the bolt has a pyrotechnic device to set it off, and that also signals ignition of the separation motors. There are four down here on the bottom, and there are four up here on this frustum.

So all of that, timewise, is essentially simultaneous.

COLONEL LINDSAY: The destruct commands, the commands you pray you never have to send, in the case of the shuttle are through an encoding device that is built and provided to us by the National Security Agency. And each mission has a different code, and it is completely independent of the shuttle system. It is separately




transmitted and received.

MR. SMITH: As host, could I suggest we break for a few minutes? Lunch is outside.

MR. MOORE: Before we do, let me discuss with the Chairman his druthers this afternoon. We've obviously spend a lot of time on this part, and there are also going to be a lot of very interesting things this afternoon. Is your cutoff time somewhere around the 5:00 p.m. timeframe? Is that something we should target for?

CHAIRMAN ROGERS: Well, I think, myself, and any other members of the Commission could speak for themselves, but I think we should do as much as possible today, and I think we ought to cut down the social activities, although it is nice, but it is so vital that we know about all of this as quickly as possible. I mean we are here to work and not to enjoy ourselves.

MR. MOORE: You are getting the latest data information that we have from all our teams.

CHAIRMAN ROGERS: That is vitally important, and that is what we are here for. I would like to work as late as we can stand it.

MR. MOORE: We will proceed with the agenda as we have it right now.

MR. SMITH: Lunch is self-service outside for




everyone. And, please, eat off your tray so we can just take the trays back out and pick it up in a hurry.

(Whereupon, at 1:05 p.m., a luncheon recess was taken, to reconvene at 1:45 p.m., this same day.)


[Please note that some of the titles to the references listed below do not appear in the original text. Titles are included to identify and clarify the linked references [Note: some of the links below display pictures/charts that also appear in Volume 3 - Appendix N]- Chris Gamble, html editor]

[446] [Ref.2/13-1] PRE-LAUNCH/ASCENT TIMELINE. [Ref.2/13-2] OUTLINE.

[447] [Ref.2/13-3] PRE-LAUNCH TIMELINE.

[448] [Ref.2/13-4] STS 51-L TERMINAL COUNT.

[449] [Ref.2/13-5] STS 51-L WEATHER SUMMARY.

[450] [Ref.2/13-6 1 of 4] STS 51-L ASCENT TIMELINE.

[451] [Ref.2/13-6 2 of 4] STS 51-L ASCENT TIMELINE. [Ref. 2/13-6 3 of 4] STS 51-L ASCENT TIMELINE.

[452] [Ref.2/13-6 4 of 4] STS 51-L ASCENT TIMELINE.

[453] [Ref.2/13-7] Vehicle roll program initiate.

[454] [Ref.2/13-8] SSME engine throttle commands.

[455] [Ref.2/13-9] Vehicle roll program complete.

[456] [Ref.2/13-10] Start of liquid hydrogen ullage pressure deviation.

[457] [Ref.2/13-11] Systems Integration STS 51-L Dynamic Pressure. [Ref.2/13-12] Systems Integration.

[458] [Ref.2/13-13] Systems Integration.

[459] [Ref.2/13-14] MPS liquid oxygen pressure rise rate decrease.

[460] [Ref.2/13-15] SRB pitch rate upset.

[461] [Ref.2/13-16] Start of main engine large pitch variation.

[462] [Ref.2/13-17] Vehicle maximum lateral acceleration.

[463] [Ref.2/13-18] Liquid oxygen inlet pressure drop.

[464] [Ref.2/13-19] RCS thruster chamber pressure fluctuations.

[465] [Ref.2/13-20] SRB yaw and pitch rate divergence.

[466] [Ref.2/13-21] SRB throttle bucket and divergence.

[467] [Ref.2/13-22] Systems Integration Observations.

[468] 854



(1:45 p.m.)

MR. MOORE: Mr. Chairman, this is Charlie Stevenson of the Kennedy Space Center here, and he is in charge of our photographic team analysis, and we are going to try to give you a fairly comprehensive rundown of a lot of the photographic data that we've got from Flight 51-L.







MR. STEVENSON: I guess what I'm going to try to do is give you a quick rundown of where we are, and show you some of the things we have come up with. We have a variety of visual aids here we are going to try to run.

(Hereafter, a film was shown.) [Not published]

First we are going to show you the film from our 70 millimeter cameras. We have picked the ones that show you the best views. Of course we don't have a 70 millimeter projection here, and so the machine we have will be this one, which is older than I am. As a matter of fact, it was going out when I was young. But we're going to try with this one. It is an analysis type machine, and it is not there for projection, but we're going to try it anyway. So let's go on, Gary, and we will slow it down when we need to.

What I will do, as we run along I will stop, and as we get into the other film, the things I am pointing out will become more and more obvious as you see more of them.

VICE CHAIRMAN ARMSTRONG: Is this 70 millimeter?




MR. STEVENSON: This is 70 millimeter. Now this camera is located at Pad A, and it looks north at the orbiter part of the vehicle. And the reason we have it is it shows a good example here of the smoke cloud. And we show it in this camera because it is all the way around the vehicle looking through the vehicle, more or less, at where the cloud is here.

MR. SMITH: The Commission members may want to get up closer, because some of this is hard to see. I'm sorry.

VICE CHAIRMAN ARMSTRONG: Now it appears to me that that could be geometrically located very close to that. Am I wrong about that?

MR. STEVENSON: Yes, sir. As I go along, I will show you some viewgraphs later that will more or less show you where that is coming from.

DR. WALKER: Is there a blemish on the screen?

MR. STEVENSON: Yes. This is a very old machine, and we cleaned it as good as we could last night. You are actually looking at a view like this, side to side, from Pad A.


On the TV system, which we will show you later, we can start and stop and really show you exactly what we have. This is the ET attach ring right here.




DR. FEYNMAN: I notice it is higher now.

MR. STEVENSON: We're going to walk around the vehicle this way with our projection until we get around the back, and so several additional films will be available.

[469] MR. SMITH: This is Dick Smith speaking. If I could point out, it appears on all the films that the smoke was projected upwards initially, and you kind of fly up through it, and so you do see the change in elevation, and it does appear to be above the joint, the large cloud.

MR. STEVENSON: It comes up and touches 30 feet or so, and then we fly on out.

MR. SMITH: We apologize for this projector. It was flown in from Houston last night. We were trying to find a projection machine we had out in the other area. We had one we couldn't move. This is an antique machine, and as you can tell it does not work very well.

MR. STEVENSON: We usually look at 16 millimeter, and if we see something we're interested in, then we go to the 70 millimeter.

CHAIRMAN ROGERS: Do you think that is smoke, or something else?

MR. STEVENSON: That is definitely smoke.

CHAIRMAN ROGERS: It almost looks as if it is




continuing to come out.

DR. FEYNMAN: It is flying up.

CHAIRMAN ROGERS: I guess what I was wondering about was whether there was a leak.


MR. STEVENSON: Okay, you can see it as we reach about this level, the 200-foot level. The cloud has actually disappeared, and from many camera angles. We only have really one camera that really shows the puff good down at the bottom. So we can see at a later time when the cloud of smoke begins to appear again.


With this camera, we are able to - we ran out of form before we got to the critical point of where we saw the plume in question. This camera eventually looks right up at the bottom as we gain altitude. Now the little dark spot you see on the aft dome are normal. That is just charring. There's nothing abnormal about that. Occasionally you'll see a little white puff come by.

DR. FEYNMAN: Is that normal, too, the white puff?

MR. STEVENSON: We do see that.

DR. COVERT: The boundary of the righthand plume is considerably furrier than the other




DR. FEYNMAN: But you're looking at a different part. One is below; the other is above.

MR. STEVENSON: Okay. As we continue to rise in altitude, you'll notice we are looking more and more into the dome. And on the lefthand rocket, the area we are concerned with, you can see very clearly on the lefthand - I'm talking the lefthand, not righthand - you can see the ET ring here (indicating). This little ring (indicating), the structural ring that we attach, the ET, to the external tank, and this is also the area that we attach the orbiter to the external tank. So that the SRB ET ring right here is on the other side in this area (indicating). This is where we see the plume.

We won't see it on this film, but we will see it on the next one. Go ahead.


DR. FEYNMAN: Can you stop it there? Is this the plume?

MR. STEVENSON: What you see here is the IEA, which is the same as this (indicating).

MR. HOTZ: What is that red area there?

MR. STEVENSON: This is the bottom of the aft dome of the external tank.



[470] 860


MR. STEVENSON: In the area of the righthand booster, you now begin to see more smoke in this area than we were seeing before. Some of it is attributed to the flame being this way toward the camera, rather than just let's say smoke coming off the righthand booster.

DR. FEYNMAN: Do you know what time it is now?

MR. WAITE: Aren't you looking through the exhaust of the main engines, as well?

MR. STEVENSON: Some. Now this, the second film, is from camera site 10, which is north of Pad B, several miles north of Pad B, and I apologize for the orientation, but the image goes into the camera, and we need one more lens in it to turn it around correctly. But let's run it.


Here you can see your righthand SRB here (indicating), with the plume here (indicating), and the smoke. The aft dome is in this area. This is just a reflection.

DR. FEYNMAN: From the beginning of the plume until now is about how long?

MR. STEVENSON: The first flame was visible at about 59 seconds.

DR. FEYNMAN: And when is this, now?

MR. STEVENSON: You're probably talking about 65




seconds or so, in that timeframe.

DR. COVERT: Now there is, it looks like some strings coming out, or some little things being thrown out. Has it exploded already?


DR. COVERT: Do you see right below the plume? To the left it looks like there are hot particles being ejected.

MR. STEVENSON: What is happening here is that the plume is beginning to wrap around the rocket case, so it is just expanding. The rocket case is that way (indicating), up.

DR. COVERT: So that is just the reflection along the line of the cylinder?

MR. STEVENSON: Yes. It actually wraps around this way, between the orbiter and the SRB. It will come around the other way, and then actually they will meet here in the middle.

As we go along, we will show you a better one of this that you will be able to orient yourself. You see the tail is up here instead of down. The film was just taken the wrong way. So here (indicating) is the tail of the orbiter, the righthand wing, the external tank, the righthand rocket.

MR. SMITH: Why don't you stop it right there,




Charlie, and explain what you've got. It's wrapped all the way around just about now.

MR. STEVENSON: Now you can see the flame coming between the lower surface of the orbiter, the righthand SRB, and around the backside, what I call the backside, the minus-, side of the SRB.

MR. WAITE: Why wouldn't that just melt the case and cause a separation?

DR. LUCAS: That analysis is under way to respond to that very point, and you will hear some of it this afternoon.

MR. STEVENSON: This is just a reflection off the smooth part of the external tank inner tank area.

DR. FEYNMAN: Which way is that moving through the air?

MR. STEVENSON: The orbiter normally flies down toward the ground.

MR. SMITH: What is the angle of attack it typically flies, Dick?

[471] MR. KOHRS: At 65 seconds, it's about 2 degrees negative.


MR. SMITH: Stop there a second.

MR. STEVENSON: This is the right rocket, and you can see the chute coming out here, the drogue, and the nose cone is long gone. And here is somewhere, if I remember correctly - well, we missed that. This is the plume we were referring to. And of course the nozzle here, the aft skirt, and the aft booster. The chute blooms, and then is immediately consumed. Okay, this third one, again, is - there is your plume. This time it is aligned correctly. This again is the lefthand rocket this time. The righthand rocket on the other side. The plume is coming toward you. The orbiter is here, and the external tank.

DR. RIDE: Are we seeing the plume wrap around?

MR. STEVENSON: Yes. (Pause.)




MR. STEVENSON: You can see here, it has now spread to where it is around between the orbiter and the external tank, and in this case the lefthand rocket.


DR. FEYNMAN: The last time we saw the plume it was coming out and down, and now it's supposed to be coming out and around and between?

MR. STEVENSON: The plume over here is coming under this way and out here and in between.

MR. SMITH: Speak up a little louder, Charlie, so everybody can hear you.

DR. FEYNMAN: This must be later, then, from when you had the other picture.

MR. STEVENSON: Yes. And what we have found, what we are doing in all of these, we are going back and making 8 x 10s of these, and we are putting the exact time reference on each frame so we can giggle them where they should be, and that way we will get the three-dimensional analysis.


We can slow this down for you when we go to the TV tapes, and we will show you this in more detail than we can show you on this machine. This was the loss of the LOX tank, and we can see on film that it actually lifted right up and we can see sky completely under the




forward top of the LOX tank. It blew the top right out.

DR. COVERT: Is that a vaporization pressurized, a heat boiloff, heat boiled off oxygen?

MR. SMITH: Yes, from the engine.


MR. STEVENSON: Again, we're really not dwelling on these type objects here, but this is the orbiter. And once again, the righthand rocket that you can see here, the extra plume that we have that we normally would not have.

MR. HOTZ: What is that on the lower left?

MR. STEVENSON: That's part of the orbiter. We have passed the part where you can see the cabin and the lower portion, but there is some question about the RCSV. We think it is an explosion following behind. Again, you can see the chute and the obvious two plumes here.


[472] This is the wing, by the way. The wing just came across here.

DR. COVERT: Are these all manually aimed?

MR. STEVENSON: Some go with radar. They are remotely tracked, and they are corrected as we need them during flight. (Pause.)




Again, this is the right SRB, and the left one is here (indicating).


This film was underexposed in order to study the plumes, to get an idea of what the plumes look like, which fell right in line with what happened. In this case you'll be able to see the extra plume we have.

MR. ACHESON: What angle are we looking at here?

MR. STEVENSON: We're looking right up the bottom.

GEN. KUTYNA: What would you call that?

MR. STEVENSON: I would call that inboard toward the minus Y from the struts. And I will show you by viewgraph.

DR. FEYNMAN: You were going around the circle, weren't you, with the zero angle?

GEN. KUTYNA: It's not on the bottom of the solids?

MR. STEVENSON: It's in between the rocket and the external tank, and I will point that out on the viewgraph.


You see now you appear to have what is three plumes instead of two. This one here, the top plume,




you normally don't have that.


DR. FEYNMAN: Did you have a special camera set at a lower sensitivity?

MR. STEVENSON: We had a camera just to look at the SRB plume. Okay, this again is the righthand rocket. You can tell by the extra plume we have off to the side. You can see it rotate around. Hold it just a second. This is when the range safety system destructed the vehicle. A typical type range safety system destruct. Okay.


Here's the frustum right here. The forward part, this part here of the SRB actually under magnification is in extremely good condition. A little bit of smudge marks, but it generally is in good condition, at this point anyway. Now that's the end of that one. Let's turn the lights on again, and let me orient the guys as to where we were.

CHAIRMAN ROGERS: Is there anything about that that you can tell us that is significant to you, more than what we observed? Can you draw any tentative conclusions from that? What I've learned is that you have a little smoke early on in the first seconds, and it disappears, and then the plume, and more smoke about that same time. Is there anything else of significance that you can draw from that?

MR. STEVENSON: Well, I think - can I show you the TV version, and that will be able to answer your questions a lot better. Let me have the three viewgraphs on the smoke, please.

(Viewgraphs.) [Ref. 2/13-23]

[473] MR. STEVENSON: Okay, left to right timewise. The one on the left on this side under screen A is typical. The photo was taken out of a long stream. I just went and pulled one out just before the smoke started, and the smoke again is in this area here (indicating). And I will show you viewgraphs in a minute that will describe this entire area here.

GEN. KUTYNA: Where is the field joint?

MR. STEVENSON: This is the ET attach ring and the field joint is roughly a foot above that. I will show you that in detail in just a few seconds here.

MR. HOTZ: Where is the smoke coming from in that first picture?

MR. STEVENSON: Over here in the first two frames, we have no visible smoke. In the middle frame on the B, we have the smoke here. It actually goes up to right about here. It goes 25 or so feet up the vehicle.

DR. FEYNMAN: You mean it starts low and goes





MR. STEVENSON: Yes. It starts here, goes up, and we fly out of it.

CHAIRMAN ROGERS: What is the length of that smoke?

MR. STEVENSON: It's about 25 feet tall.

GEN. KUTYNA: Is the dark area on the bottom of the ET, is that smoke - that dark shadow?

MR. STEVENSON: Yes, sir. You see, we're already flying out of it. This is about the sixth or seventh frame where there is smoke. I'm just going downstream a little way so it is obvious to everyone that it is there.

MR. RUMMEL: Does the solid motor burn out up to that joint at that point?

GEN. KUTYNA: No, it burns the whole thing.

MR. RUMMEL: The entire length?

MR. STEVENSON: Right. You burn from here down internally.

MR. RUMMEL: It's ignited at the upper end up there?


DR. WALKER: When it's ignited, how long does it take for a fire to start? Does it start very quickly, I imagine? It ignites at the top?




MR. HARDY: It is microseconds. Just a very short time.

MR. STEVENSON: The smoke is real small in here and going up.

MR. WAITE: Do you think those are combustion gases?

MR. STEVENSON: I think these are carbon particles in the materials that make up the joint, is my opinion.

MR. WAITE: So it is just pressure leaking out? What is it that's leaking out?

MR. STEVENSON: Black smoke is what we see.

DR. WALKER: How long after the ignition is the first frame?

MR. STEVENSON: Rough time showed this to be about 610 milliseconds.

CHAIRMAN ROGERS: Going back to the question before that, what do we think is leaking out? What do we see as smoke? Do we have a guess?

MR. STEVENSON: I'm guessing, but to me it is the SRB exhaust coming through the field joint, and you are seeing the hydrocarbon particles that make up the joint is what makes the black smoke.

DR. COVERT: Could that be O-ring material?

MR. STEVENSON: It could be O-ring material. It could be



[474] 871


grease and putty.

DR. COVERT: Putty is zinc chromate. That probably doesn't burn black.

MR. SMITH: Mr. Hardy is going to try to cover that when he gets up.

DR. WALKER: One other question. In the first frame - -

MR. SUTTER: Could I ask a question? Can't you run a test and find out what the hell it is? Can't you set one of these things up, and build a leak, and blast it, and see what the hell it looks like?

MR. HARDY: We know that the product combustion of the grease in the joint that blows the O-ring would be black, dark in color. The insulation on the external tank would be black if it were burning - the foam insulation. So there are at least two things that I just mentioned that could be black.

MR. SUTTER: But it seems to me that maybe this is not the cause of the accident, but this is certainly one thing that might be. And it seems to me you guys would be going hell bent for election running tests.

MR. HARDY: We are, and I plan to talk about that.

DR. LUCAS: If we could look at this as




background, George Hardy plans to take these step by step right along and describe what we know.

MR. SUTTER: I know, but I think the Chairman was reflecting a little bit of the frustration. We're not trying to solve the accident. We want to do it in an orderly manner.

DR. FEYNMAN: The orderly manner is first to get the facts and see what we see, and then hear an interpretation, because the interpretation might be wrong. But what we see, we see, and might be right. So the orderly way I think would be to look closely at it and see what we see, and then hear what they think they see.

MR. SUTTER: But this is not something that has been leaked to the press yet.

DR. FEYNMAN: We don't care about the press.

MR. SUTTER: Well, this is going to get out to the press, and I don't think it would do anybody, the Commission or NASA or anybody, any good to say we really don't know what the hell that is.

DR. WALKER: Could I ask one question? In the first frame, how well localized is the smoke, and exactly where is it on the first picture of the smoke that you saw? You say this is the fifth one?

MR. STEVENSON: There are four or five in




front of this, and we actually first see it here.

DR. WALKER: It's really pretty close to the seam?

MR. STEVENSON: It's really big when you first see it.

DR. WALKER: It overlaps the seam?

MR. STEVENSON: We can't quite see the seam, and I will show you where we can see it in just a minute.

CHAIRMAN ROGERS: But just for our purposes, now you sound as if you think it is most likely coming from the seam.

MR. STEVENSON: The field joint.

[475] CHAIRMAN ROGERS: Is there anybody of the opinion that thinks it's actually coming from the external tank? I realize you can't exclude it as a possibility.

MR. HARDY: We have not excluded it as a possibility.

CHAIRMAN ROGERS: But the more likely possibility is the one he says?

MR. HARDY: That certainly is a possibility.

CHAIRMAN ROGERS: The more likely possibility? I'm just trying to figure out your thinking. If it should leak out, I gather that is one that seems more likely?




MR. ACHESON: Not to anticipate, but what is there in that vicinity structurally, that would permit leakage of some material?

MR. HARDY: Well, the external tank is covered.

MR. ACHESON: Is there a seam there, or any valve?

MR. HARDY: There's a number of longitudinal welds, circumferential welds around the tank in the general region between the booster and the tank.

CHAIRMAN ROGERS: So it is possible that something might have happened to the external tank that would cause this black smoke?

MR. HARDY: Yes, and I do plan to discuss that.

MR. RUMMEL: I would like to return, if I may, to Joe Sutter's point. Do you plan a test to examine the design of the rings once more and what the nature of the smoke is, and that sort of thing? It seems to me that should be something that should be of interest.

DR. LUCAS: Yes. We're going to discuss the test program.

MR. RUMMEL: When? Oh, you going to discuss that? Oh, all right.

CHAIRMAN ROGERS: Why don't you move along?





DR. COVERT: What is the framing rate of this camera?

MR. STEVENSON: I'm sorry. I don't have that with me. There's a big thick book of all those things.

DR. COVERT: I'm curious what the time is for this plume to go 25 feet up in the air in four or five frames, and I wonder what the drift velocity is of that plume.

MR. STEVENSON: We haven't worked on that yet.

CHAIRMAN ROGERS: Why don't you go ahead?

MR. STEVENSON: We just picked a third series of photos here that show that when we are roughly at 200 feet in elevation, the black smoke has disappeared, and it is some time again before we can positively identify it as a matter of fact completely out of the frame.

MR. SUTTER: Could I make a point? Maybe I've got the cart before the horse, but if you look at this sequence of shots over here, the main motors are just about up to power, right?


MR. SUTTER: And when they do, they bend the whole machine and it is held to the ground, and you've got a structural joint where that bending, really a lot of that load is going right into that joint. Isn't that right? And that might be changing the seating of those




seals. And I'm just throwing out a theory, and I would like to get a comment on it. I will tell you the whole damn theory, and you can tell me how crazy I am.

As soon as that happens, then you put the solid rocket booster motors on, which reorients the whole load. That might be changing the seating of those seals again. And just about when [476] that load changes again, then you see the smoke. And when you get around to this testing, it seems to me you ought to run a test where you put those great big hellish loads in, in the direction they are here. You've got the right pressures, and you build a leaky seal, and you see what the hell happens.

This is why I sort of get antsy. Are you going to do a test? And how real is it? I think these ground-holding loads, and the changing of loads, and maybe a slightly worn eroded seal, could be the whole damn trigger. And I'm going to pursue that test. And if it's a few million dollars, or it takes a month, what the hell. I think there ought to be a hellishly good test of that.

DR. LUCAS: Well, certainly, sir, we do plan to do some testing. Let me just mention two things, though, that fall in line with your theory. One is, when the Space Shuttle main engines ignite, as you




suggested, the whole stack leans over away from that application of force, and the thing is calculated such that just as the tip of the tank comes back to the vertical, then the solids ignite.

Now that is one of the things we are looking at. In case that was a little bit off, it would put a different load pattern into the stack. The maximum bending moment, however, on the SRB is not at this joint, but at the joint above this one. The maximum bending moment is, at that joint, however, at max Q. And so we are looking at those things.

And as you have already observed, this first light flame occurs at about max Q. And that happens to be the position of the maximum bending loads on the SRB at that time. So we are looking at those things, and I'm sure some test programs will ultimately be required.

DR. COVERT: And that's also the point where there is the maximum windshear.

DR. LUCAS: That's right. All those things are fact.

DR. COVERT: I'm not speculating at this point. I just want to see if I'm right.

MR. MOORE: Those are the factors that we're looking at.

DR. COVERT: Thank you.




MR. MOORE: The other thing in this thing is it may turn out that a test like that is going to be required, and so forth. You know, we do flight readiness firing in preparing and checking out the new orbiters where you just simply keep the system bolted to the mobile launch platform and bring the engines up to their rated thrust. So that may be a test that we're going to have to go back and do.

DR. WALKER: But you don't fire the solids.

MR. MOORE: No, we do not fire the solids, but you can get a feel for what the loads are on the solids prior to liftoff.

DR. WALKER: But the launch pad couldn't withstand a full firing of the solids?

MR. MOORE: No. No, sir. So those are the kinds of things we're going to be looking at in terms of laying out a test program, and additional test programs may be required for the solids themselves.

DR. WALKER: When you test the solids, of course, on their test stands, they don't have these kinds of moments.

MR. MOORE: You normally test them on the horizontal.

DR. WALKER: We could impose those bending moments on it.

DR. COVERT: It would be hard to put the




dynamic moment on it. The static ones you probably could do.

[477] DR. LUCAS: That's right. And we did, of course, in the test program.

MR. MOORE: There could be dynamics for the mobile launch platform, as well as the base mount and pad itself.

CHAIRMAN ROGERS: Okay. Out of a matter of politeness, let's let the briefer finish his briefing, and then we will ask the questions.

MR. STEVENSON: Let's have the next series of slides on the ET ring.

(Viewgraphs.) [Ref. 2/13-24]

I'm going to present several slides here that will show you roughly what the ET ring looks like, starting with the orbiter here, the main structure, attach structure between the external tank and the orbiter. The large pieces - -

DR. WALKER: Is this 51-L?

MR. STEVENSON: This is the vehicle, right. As a matter of fact, you see the frost here. This was taken at T minus 3 hours. The cable tray that goes between the SRB, across the ET and to the orbiter. The upper strut, which is well protected with what we call a milk can. It is a stainless steel fairing that goes, which has cork on it to protect the cabling between the external tank and the rocket.

The IEA unit - -

DR. COVERT: What's that?

MR. HARDY: The integrated electronic assembly.

DR. COVERT: Thank you.

MR. STEVENSON: In a lot of our films, you will see this reflection because it is white. You also will be able to see the strut. This is the ET attach ring where we attach the rocket to the external tank. The cable tray is on the Y axis outboard of the vehicle and runs the entire length of the rocket.

DR. LUCAS: Would you point out the pressure checkport up there?

MR. STEVENSON: I'm going to go all the way around it. I'll get to the back in just a minute. We stopped at the cable tray here. Here is the cable tray again. This is the IEA, the end of the IEA assembly, the ET attach ring, back around to the Z. These are stiffener rings which we put foam on to protect from water impact. We do get a little gassing on these during the ascent, which does attribute to some of the smoke you see under the bottom side of the engine.

The next two.

(Viewgraphs.) [Ref. 2/13-25]




We are moving now from here, which is this point. This is the backside which is in question as to the plume. Our analysis says the plume is in here. The leak checkport, which you will hear, or have heard, or will hear much about today, is here.

DR. COVERT: So that is minus-Z ?

MR. STEVENSON: Minus-Z on the righthand booster is right there (indicating). Well, I'm saying it's there. It is supposed to be along in there, I believe. But I'm assuming that is what that is.

DR. WALKER: That is frost on that bracket.

MR. STEVENSON: Yes. The external tank. This is what we call the EV fitting, and this is the lower strut, the lower righthand strut. This fitting is flown bare. This way, as a matter of fact you can see the green paint here. It is isolated from the hydrogen tank.

DR. WALKER: This is where the glass insulators are.

[478] MR. STEVENSON: Yes, there are phenolic insulators right under here. There are six bolts on the bottom, and six on the top. They do have a layer of insulation on them to protect them.

GEN. KUTYNA: Dr. Lucas, the distribution of stress around that circumference, is it equal or are there points where it is greater or lesser?




DR. LUCAS: I think there are points where it is greater.

MR. HARDY: Yes. Are you talking about on the booster, or on the tank?

GEN. KUTYNA: On that solid, on that joint, as it bends through all these moments, is there a point where the stress is greater? And might it be at that point where it is connected to the ET?

MR. HARDY: It would be higher up above.

MR. STEVENSON: It would be higher in this area (indicating).

GEN. KUTYNA: Where the general higher stress is on SRB?

MR. HARDY: In that black area.

MR. STEVENSON: Again, I didn't point out the diagonal strut, which is on the other side. You couldn't see it in the first series of pictures we showed.

DR. WALKER: There are actually three struts, and there are only two on the model.

MR. STEVENSON: There is another one on the backside here. The lower strut is flown bare, with the exception of under the bottom here is where we have the ordinates, the cable comes across here and goes into here for the separation. So we do protect the ordinates




wire, and this also has a layer of insulation on it.

DR. COVERT: Is that an optical illusion on that dark-colored cover there, that it doesn't stick up, that it just projects forward?

MR. STEVENSON: It does come out here. This is for this joint to move. So it isn't just a flat surface circumferential type cover. It does have a leg in it like that.

DR. COVERT: Go ahead.

MR. STEVENSON: It is to make that square with the strut. As a matter of fact, you can see it better over here.

DR. COVERT: Has it always been that way?

MR. STEVENSON: This design, yes, sir. You can see the joint here. You can see the grease here.

MR. RUMMEL: Is any degree of relative motion possible between the tank and the SRB with all that insulation?

MR. STEVENSON: Back and forth this way, practically none. The tank does rise about 4 inches when we tank it, and the strut becomes horizontal. The tank shrinks as we go to cryo temperatures and the tank goes up to the forward attachments, so this part of the tank moves up to the beam here during cryo loading, and this strut becomes horizontal.

Normally, if you looked at it untanked, it would




have as much as I believe 8 degrees cant down. Let's go to the next three slides.

(Viewgraphs.) [Ref. 2/13-26] [Ref. 2/13-27]

I included these this morning to show about some of the lines of sight of the cameras, and the particular ones I'm showing you, we have camera flats around the pad as well as up on the pad and out on the beach, and as far north as Ponce de Leon, and as far south as Melbourne.

[479] The camera, like one of the cameras I'm showing you, happens to be located here and looks at this angle. And what we're doing, what I've done here, when we finish, camera E-60 sits over in this northeast corner of the pad, and the field of view of camera 60 shows that I definitely can see the Z axis where the leak check plug is. I very plainly can see this part of the vehicle, and should be able to see the strut. Looking from this way, the camera on the other side of the pad on the northwest side of the pad, I can nearly see the same thing.

So by doing a comparison of all of our charts, we will be able to say exactly how far in this way between the crack we will be able to see.

Okay, what I would like to do next is just go through about ten minutes of this or so. We have a TV.




We can start and stop that. The TV shows some things that are much more detailed than you were able to see on this one. So I guess if we could cut the lights again.

(A film was shown.)

Again, this camera is from Pad A looking north at Pad B. Why don't we just run this one through? This is one series. Let's just run it through and we will come back and pick this one up a little later.

We are going back and reviewing all of our data from previous flights. Part of this smoke is not unusual. As we go higher in altitude, the amount of smoke you see here does become unusual, and it will actually engulf part of the wing before we finish. We probably edited this one too much.

DR. COVERT: What was that bright spot up near the bow of the righthand booster?

MR. STEVENSON: We have a shockwave in here.

DR. COVERT: No, earlier.

MR. STEVENSON: It's condensation.


This is the same camera, and here's the spot here (indicating). The next one - we haven't seen this one before, but you will see the smoke right here. This is a TV, black and white TV, camera located on the top of the pad.


Again, you can see the plume.


GEN. KUTYNA: There appears to be a rotation in that one on liftoff. Is there any oscillation, or is that my imagination?

MR. STEVENSON: I think the oscillation you saw right at liftoff was in our transposing the camera. This came off a 35 millimeter, transposing to a videotape. It actually came off a 16 millimeter.


Okay, in this one we're going to slow it down for you, but you see the plume here (indicating). Again, this is actually the lefthand SRB. The righthand was behind, and the flame is coming towards you. You will see it increase around to this side, and you can see it flash in here, which is actually coming all the way under the dome, and it is actually on the lefthand SRB.

DR. WALKER: It is just surrounding the tank.

DR. COVERT: The flame on the tank is attributed to the oxidizing nature of the exhaust, and the combustion products?

[480] MR. STEVENSON: Well, I think the flame you see here is actually coming from where 1 think it was actually coming from the righthand SRB.

DR. COVERT: So there is no combustion?




MR. STEVENSON: The heating, the charring of the foam can have a combustible out-gas. but it chars.

DR. COVERT: You're saying it's later, in other words?



This again is the one we partially underexposed for the flame.


In this sequence, we were showing what we feel is our scenario, anyway, of how we are losing the forward part of the hydrogen tank and the LOX tank. As the flame increases from here over to here (indicating), we will see it propagate around the ring frame here. You will also at the same time we see it - do you want to stop it, Pete; back up for just a second - okay, we feel that at this timeframe we have lost the weld joint, or the barrel section just about the weld joint, between the weld joint and the 2058 ring frame, which is where the aft dome attaches, and the hydrogen we feel is coming out here.

DR. FEYNMAN: That is the joint that usually carries the hydrogen? No, it has nothing to do with that?

DR. WALKER: So you think you lost the hydrogen feed, too?




MR. STEVENSON: No, sir. The hydrogen feed is over here. I believe we lost the weld, just the weld joint. It just unzipped.

MR. RUMMEL: So you've got a hole in the main tank now?

MR. STEVENSON: Yes, where the barrel section joints the main ring frame here to the aft dome. But once again, we feel this is coming from the righthand SRB toward us.

DR. FEYNMAN: You see, it flashes up there. Is that hydrogen coming from somewhere else?

MR. STEVENSON: We believe also about this same timeframe, due to what we feel, and based upon the gyro data we have, that we actually lost this strut on the lower end here, and that this rocket had freedom of motion to cause a problem in the inner tank. And what you see here is the hydrogen coming from the inner tank, and this now again we are looking at the side that has the minimum amount of activity.

There is considerably more leakage on the other side, and this flash from here we feel went around the back side of the vehicle, and you see it here again. And then it propagates up.

CHAIRMAN ROGERS: When you say "vehicle," what




is that?

MR. STEVENSON: The external tank and the orbiter.

DR. COVERT: But the negative angle - but this is at a negative angle of attack, and so that is the windward side, and so you were at some mach number like 4 or so?

MR. ALDRICH: Mach 2.

DR. COVERT: Okay. I'm not going to quibble about a factor of 2. Then, unless there is some separation there, I don't believe the propagation of a hydrogen flame will go upstream against a [481] mach 2, because I think the hydrogen flame propagations are around at 150 meters a second. So what is happening, causing it to move forward that way? As I say, if there is some separation there, then you could have the separation as a dead zone, and you could propagate forward, but you are at a negative angle of attack, and it should be relatively clean in there.

VICE CHAIRMAN ARMSTRONG: How well do you think we can identify the time of these TV frames?

MR. STEVENSON: Pretty well, within two or three frames, two or three thousandths. We feel that about 73.1 seconds we lose the aft barrel section on the hydrogen tank.




MR. HOTZ: How many seconds?

MR. STEVENSON: About 73.1, and approximately 70 milliseconds after that is when the inner tank and hydrogen tank fails, along with, followed immediately by the LOX tank mainly on the righthand side, but you can see here, we do have other photographs that show a lot of activity on the other side that you can't see in this frame.

We calculate this area to have been 73.2 seconds, roughly a tenth of a second difference.


You can see more action on this one than you did in the last one.

DR. COVERT: Could we go back and start that one all over again, please? And could we go a frame at a time?


Thank you.

MR. STEVENSON: We have already had the mixing of the LOX and hydrogen in this area, about three frames.

DR. COVERT: In fact, that may even be a detonation.

MR. RUMMEL: What evidence is there that the strut failed?

MR. STEVENSON: We have in the TM data we have




a rate change. The gyro rate.


Again, the righthand SRB, and we believe we actually have part of the external tank we feel still attached to it, and it is actually burning out around it.

DR. COVERT: So you think that external tank held and the external tank failed, and you took a piece with it?

MR. STEVENSON: Yes, sir.


Again, your righthand rocket and lefthand.


This is the righthand rocket again, and actually this stage appears to be in excellent shape, except for this area. And of course the front shows a little more burning than we normally would see, or a little more charring.


This is the righthand rocket which is going to destruct in this one. You've got two plumes.


There's the destruct. And again, the righthand rocket actually showed very little. It was still intact the last time we saw it. And we feel that


[482] 892


at least in our frames it was still intact, except for the forward assembly. The lefthand SRB, the destruct on it was what we would call normal, in that the pieces, the actual segments separated and we are only left with the aft booster portion.


[Please note that some of the titles to the references listed below do not appear in the original text. Titles are included to identify and clarify the linked references - Chris Gamble, html editor]
483] [Ref. 2/13-23] 51-L LAUNCH.

[484] [Ref. 2/13-24] [Attached structure between ET and SRB]

[485] [Ref. 2/13-25] NOT REPRODUCIBLE.

[486] [Ref. 2/13-26] NOT REPRODUCIBLE. [Ref. 2/13-27] NOT REPRODUCIBLE.


[487] MR. MOORE: That is some of the photographic data we have. We are working on the enhancement of this with some of the best experts in the country. In fact, we got some people from Los Alamos working on this to try to blow up certain segments of this thing and see if we can duplicate this. But that is kind of what we thought was relevant to let the Commission see, and the kind of data that we do have in hand.

And we are going through, as I said, additional analysis.

CHAIRMAN ROGERS: It seems to me, from looking at it, very convincing. Why don't your photographs exclude the external tank?

DR. LUCAS: We're going to talk about that, and that may be the way it turns out. But I'm not prepared to say. I think there's a strong probability that a leak from the tank was then triggered. The thing that gives me the most trouble is how does one explain a leak through a joint in that rocket nozzle that lasts as long as it does. You see it's running for 100 seconds.




I think we will show some calculations that say if that hot gas is going through that period of time, you would have a large hole in there. And I believe the analysis will say, although they have not yet been done, that the tank would come apart before you would get that far.

It may be, and I don't think there's any question that ultimately that joint gets hot and leaks hot gas. That is very evident here. But I am not certain that it did not come from a heating source somewhere else. If you have an external source heating that joint, it would have the same effect, ultimately.

This is speculation.

CHAIRMAN ROGERS: How about the first black smoke? Did that come from - could that have come from the external tank?

DR. LUCAS: Well, here's the thing. You see, if one postulates hydrogen is leaking, it burns with a nonluminous flame, and you wouldn't see it until it hit something. So if if hits that bead of grease going around that joint, for example, that would give you a puff of black smoke. If it hit the cork that overlays that band over the pins, it would give you black smoke. If it happened to hit some of the insulation on the tank itself, it would give you a puff of black smoke.

Now I don't know whether any of those things




happened, but until we can exclude that, I think we ought to continue looking at it.

CHAIRMAN ROGERS: That explains why you haven't excluded it. And so it is possible that one theory would be a leak from the external tank, which wasn't apparent, and it might cause the puff of black smoke, and it wouldn't then be more apparent until the plume - how did you get the plume on the right booster that comes from the external tank?

DR. LUCAS: I think ultimately there's no question that ultimately that joint up there allows the leakage of hot gas on the solid rocket motor. My only question is: Is the flame, the penetration of the flame, through that joint? Did it originate from heating that came from inside the solid rocket booster and deteriorated the joint from the inside? Or did it happen by a flame from the outside of the solid rocket booster that deteriorated that joint? It could be done either way.

[488] Now the thing that got my attention was that I had asked some of my people to look at how much leakage of liquid hydrogen could I have at liftoff and not detect that in any of the systems? It is about four pounds per second. That's a lot of hydrogen. Now I want to emphasize -




CHAIRMAN ROGERS: I think it is clear.

DR. LUCAS: - that my speculation has to include that one could have had a leak in the tank, and that it could have come from various sources. Maybe it is some defect. We are looking back at the tank to make sure that is not the case. It could be some piece of ice or something blew up, or something that penetrated, perforated the tank, or maybe it is a leak in a joint somewhere.

MR. RUMMEL: Could it have come from the filler valve, somehow?

DR. LUCAS: Well, that is disconnected. You mean at the disconnect?


DR. LUCAS: Well, I couldn't exclude that as a possibility. It is supposed to be disconnected, and it shouldn't leak, and I don't think it was leaking before we lifted off, because we have hydrogen gas detectors all around, and so far as I know, no detection of a leak was observed.

DR. COVERT: There once was, long ago, some leaking, if I recall correctly, in an early preflight readiness fire.

MR. CRIPPEN: That was STS-6, and inside.

DR. COVERT: Right. But it never was




satisfied to me that anybody knew where it was coming from.

DR. LUCAS: Oh, yes. We pinpointed that one.

MR. WAITE: Can the crystal be extruded through the crack by the pressure inside the tank?

DR. LUCAS: I beg your pardon?

MR. WAITE: Is this a rubbery material that can be extruded through the crack by the pressure inside the O-ring?

DR. LUCAS: The O-ring? It is rubber elastomeric material.

MR. WAITE: No, I mean the propellant itself, so it's actually burning on the outside of the tank.

DR. LUCAS: It is a rubbery material, but I wouldn't think that it would extrude out the tank. It is still, I believe, too viscous to flow through that joint.

MR. WAITE: What is it? 600 psi?

DR. LUCAS: It originally starts about 900 psi, and it is about 600 psi at the time one observes the flame coming out of the joint.

MR. WAITE: When you do your test, you can have a crack that's open on one end, then one typical of this, and see if you can get that.

DR. LUCAS: That's an idea. We ought to




consider that.

DR. COVERT: I think the propellant, and I don't remember correctly, I think it's got some aluminum trichlorate in it, some solid crystal, so it's not only got a rubbery-like material, but it's sort of like a rubbery material with sand in it. And so it will extrude with greater difficulty than if it were merely a rubbery material - at least I believe that to be the case.


[489] 898


MR. WAITE: Like you, I can't understand how you could have that much flow through a crack without eroding everything around it.

DR. LUCAS: Well, you will see some preliminary analysis this afternoon that supports that, and we also early on looked at the possibility of a separation of the insulation from the wall of the tank in such a way that because of the thermal gradient, that the flame could get down to the membrane of the solid rocket motor, and the calculations are that when you get a hole on the order of one inch - and I'm speaking from memory now - on the order of one inch or so in the membrane section of the case, it would become unstable and come apart.

MR. ACHESON: Is there anything on these pictures that is inconsistent with a leaky test port?

DR. LUCAS: No, sir. That is why I wanted to make sure we understand where the port is. It is in that area.

MR. ACHESON: But either way, it would look about the same from the photographs?

DR. LUCAS: Yes, sir.

MR. CRIPPEN: I guess you can clearly see where the test port is on the bottom side of that tank, and Charlie showed you the smoke, and it appeared to be




coming from further around the tank than where the port is. But again, it is hard to tell.

MR. MOORE: I would only qualify what Bob said in that I saw the black dot up there, too, and that was the first time I saw it. That is alleged to be the test port. I am not convinced that is the test port. I mean, that is where we think it is. That is where it should be, but it is a real dot, and if anybody can see the test port on that photo, they have got a lot better eyes than I do.

DR. COVERT: I would be prepared to guess that that is grease because it looks furry.

MR. ACHESON: Did the segments have to be put together in a way that makes the test port appear at that point?

MR. MOORE: Yes. You are going to hear about how they are stacked in what comes up. We will give you that whole sequence, but the way they are stacked is that all test ports on the right-hand booster should line up on one side of the axis, and on the left-hand booster they line up on the other side. So they all should be down a vertical line drawn down the solid rocket booster roughly 90 degrees from the way we measured the clock angle on these drawings.

DR. COVERT: When you did the wind tunnel




test, were there vapor screen pictures taken to show the shock wave conditions?

MR. SILVEIRA: Yes, we did that in oil flows.

DR. COVERT: So if it becomes a problem to trace why this flame acted like it did, there is a great body of data to refer back to?

MR. SILVEIRA: The flow between the tank and the orbiter is very, very minuscule, and it --

MR. HARDY: Excuse me. If I could mention, we are looking at setting up some tests in Huntsville where we can actually evaluate the interaction of the flow with the plumes.

DR. COVERT: And you will put smoke probes in there and so forth, and how are you going to maintain the same sensitivity constant with smoke and air as opposed to hydrogen and air?

MR. HARDY: We are just looking at how we are going to put together the tests now.


MR. MOORE: Maybe you can help us design the tests.


[490] DR. COVERT: I am supposed to be independent, and if I helped you design it, then I would have a strong prejudice to believe what I saw.




(Laughter. )

MR. SUTTER: On that very first film where there was a very isolated plume for a while and then it seemed to spread around the circumference, and then it got much bigger, but couldn't there be that you would say have that hole, for instance, the test hole, allowing whatever was coming out and starting the thing to still be heating it, but it would be working on just the seals so you wouldn't be having the total burnthrough to make it go slower?

MR. HARDY: That could be correct, and as I say, in another 15 minutes we are going to cover this.

DR. LUCAS: That is one of the scenarios we have. I think that's right. You see, if you assume this puff of black smoke comes from the solid rocket motor, then you have got to explain how it can stop.

Well, if it turned out that it came from the test port, which is a threaded insert with an O-ring around it, and if that leaked, then you could imagine that it would stay in there for a while, but there would be a slight little bleed of hot gas coming through, and I think it possibly could show with the aluminum oxide that you produce from the burning of the propellant, could choke those threads, but ultimately it is going to get hot enough to blow out, and then it quickly goes around.

MR. FEYNMAN: There is another possibility for a transient; the O-rings don't have good resilience when they are cold, and the first bit of gas that comes in gets through and makes the black smoke. And then it becomes warmer, it takes time, but it goes through where the metal is cold, and it has to warm up the metal.

I am not sure myself, and I don't know how long it should take, but warm up the piece of rubber, and then the rubber expands, fills the hole. But in the meantime, putty and junk has gotten in, and it is not really a perfect seal. It just seems to work for a while, but it gradually leaks and finally breaks down.

DR. LUCAS: I think that is a plausible scenario.

MR. FEYNMAN: I don't think it is fair to make up these things now. We should wait and hear what you say.

I'm sorry, I apologize.

DR. COVERT: It is a lot of fun, though.


DR. LUCAS: It is encouraging though that you are coming up with similar ones as we have.

MR. FEYNMAN: But in your scenario, I have a question with the hydrogen coming out of the ET tank, is




it obvious that it immediately flames, that it burns? Is that automatic?

DR. COVERT: Well, there is enough oxygen in the air that it would burn out the interface.

MR. FEYNMAN: It starts itself automatically?

DR. COVERT: The combustion ratio is 5 percent to 95 percent, or something like that, and so that it is hard to not burn in the air.

DR. LUCAS: Its flammability, its ignition temperature is very low, and its flammability range runs from 4 percent to 96.

[491] DR. COVERT: I'm sorry about that.

DR. WALKER: The hydrogen tank is welded?


DR. WALKER: It is aluminum?

DR. LUCAS: Yes, and it is a very good low temperature material, obviously, because it is containing hydrogen at minus 423 degrees.

DR. WALKER: I didn't hear the answer to the question that someone asked if you ever had any leaks in those tanks?

DR. LUCAS: No, sir.

DR. WALKER: But they do, of course, have to go over a pretty large temperature range.

DR. LUCAS: That's right, but that is - aluminum gets stronger at low temperature, and the




environmental temperature is insignificant as compared to the minus 423 degrees of liquid hydrogen on the inside.

DR. COVERT: Are those automatic welds?

DR. LUCAS: Those are automatic welds. And the tanks are all x-rayed as you may remember. All of them are x-rayed. Each one of them is x-rayed, and then they are proof tested subsequent to the x-ray.

DR. COVERT: At what temperature are they proof tested?

DR. LUCAS: I think it is ambient but I will have to check.

DR. COVERT: That is just a leak test?

DR. LUCAS: I am sure it is ambient, because if they are proofed at ambient, the strength increases by about 30 percent.

DR. COVERT: Except it gets more brittle?

DR. LUCAS: No, it gets tougher, as a matter of fact; the aluminum alloy, this particular alloy gets tougher at low temperature than it is at room temperature. That is not true of steel, and I think Dr. Walker this morning was raising some questions there. The D-6A, which is the material in the case, would not respond the same way as aluminum, but it does have a fairly high toughness even at the temperatures, at these temperatures.




DR. WALKER: The proof test is a pressurization of the tank?


MR. RUMMEL: It seemed to me the plume was almost instantaneous, a small fraction of a second. If that is the result of heating from the hydrogen, wouldn't the hydrogen leak have had to occur almost prior to ignition?

DR. LUCAS: Are you talking about for the luminous flame that appears from the SRB?

MR. RUMMEL: No, the puff of smoke. I thought you were implying that might have been the result of heating from the hydrogen flow, which could well be the case, but in any event, the leak would have to have occurred almost prior to launch, wouldn't it?

DR. LUCAS: Or coincident with.

MR. RUMMEL: And my question is, is there any way to go back over ground instrumentation or photography or in some manner to find that out? It is awfully early.

DR. LUCAS: You may be missing that the SSMEs have been burning, first one has been burning about 6 seconds before we get to the point of ignition of the SRM. You see, you ignite the SSME at intervals and the time line is when you ignite the solids, you have ignited


[492] 906


the SSMEs some six seconds earlier, and that is what bends the stack over, and then when it comes back, you launch with the solids.

MR. MOORE: I think the question that Mr. Rummel is asking is is there instrumentation on the tank that will allow you to detect a leak that was small enough or large enough, as the case may be, to cause this, or on the ground, and I think the answer to that is no.

MR. LAMBERTH: That's right. The leak detection we have looked at the 17 inch disconnect area. We looked at that with fire detectors, and we also know that enough of the purge could come from that area, comes in from the aft. We had no indication of leaks on that. We have leak detection up at the vent, but we do not have any leak detection that would cover maybe someplace in that area on the tank in the same area of the right hand SRB. If you had a leak and it did not ignite, the instrumentation and the pressure and things like that didn't see it, you would not see it.

MR. RUMMEL: If it did ignite - -

MR. LAMBERTH: I think we have enough fire detection around that if it ignited, we would pick it up prelaunch.

DR. WALKER: I think you said, Dr. Lucas, that




four pounds could be leaking without being detected? How big a hole would that be?

DR. LUCAS: Four pounds per second is eight-tenths of an inch in diameter. I want to emphasize again, I don't have any evidence at all that we have a leak in the hydrogen tank.

MR. MOORE: But just as we have been saying, I mean, we have been focusing on the solid rocket booster as maybe being a prime, and we have not resolved the external tank and so forth.

CHAIRMAN ROGERS: What about the main engines?

MR. MOORE: The main engines in my book have not been exonerated, but they look pretty clean.

CHAIRMAN ROGERS: What possible data do you have from these photos that the main engines might be involved?

MR. MOORE: We don't have any working theories at this point in time, sir, that would tell us the main engines are a contributor.

DR. COVERT: The sequence is wrong. If you threw a turbine blade into the hydrogen tank, you could have something, but then you would have engine shutdown preceding the event, and there would be a lateral acceleration and lateral feed.

CHAIRMAN ROGERS: For our purposes, it seems




to me that you always can say everything might have caused it, but with the picture and telemetry, it seems to narrow the focus somewhat, and it seems - it looks now as if it is the right booster, or the external tank tank.

MR. MOORE: I would say there are three major areas we are looking at still. Although we in my task force have not exonerated the orbiter or the main engines, they look pretty clean based upon our preliminary data, and they are likely to be exonerated. We are still looking at the SRB, at the external tank, and also the launch pad system.

CHAIRMAN ROGERS: How could that come into play?

MR. MOORE: There may have been different loads and so forth transmitted to the vehicle. That could have been the cause of this whole thing. And so we have got to go back and clearly understand what loads the system saw from the time of ignition and so forth. And so we are not [493] exonerating the launch facility at this point in time until we have done our loads analysis. So those are the three main thrusts we are working on at this point in time.

MR. FEYNMAN: Suppose that we do seem to all agree and that we have established something, which is




that the black smoke appears to come from a region which is the same region as the flame later comes from the rocket. Nobody is proposing that that is a mere coincidence.

So if I have understood our situation, to take a very elementary view without solving too many problems at once, axiom one, you have got to explain the black smoke. After that, the rest of the problems will be less important.

How long does it take before the other thing comes out and so on are clues perhaps to the mechanism of the black smoke, but are not as essential. I mean, they are just helpers.

Is that true? Is that the viewpoint we are taking, that it can't be a coincidence that these things are in the same place?

DR. COVERT: I don't rule that out yet.

MR. FEYNMAN: Good, I am glad to hear there is somebody still thinking because I have ruled it out.


MR. SUTTER: I didn't appreciate it when I was lying home in bed sick, and after the last God damned airplane left for the east coast, I was asked to be at a meeting at 2:00 o'clock on Monday, and I couldn't make it because I don't have my executive jet. But I am glad




I wasn't there because that was nothing more than to reply to a leak, and there are going to be leaks. I am not complaining about leaks, but I think it was important that we discuss these theories, and we discuss every damned thing you know, and you tell us what the hell you are going to do so that when the press hears about the black smoke, which they will, the Commission will say, hell, they've told us everything they know about it, they have told us what the he]l they are going to test for, and we will let NASA tell you about it. We have already told them what the hell we expect out of them.

I would rather help you guys investigate this rather than have the God damned New York Times or Washington Post do it.

MR. MOORE: We are with you 1000 percent on that, and if we can stay ahead of the press, we are a lot better off.

MR. SUTTER: I don't want to tell you guys how to run your test program. I know you will run a very thorough one.




MR. SUTTER: It would have been nice for us to know last Friday that this letter was out. You guys must have known that letter was out.

MR. MOORE: We sure did not know about it.

MR. HARRINGTON: We read it in the Sunday Times like you did.

CHAIRMAN ROGERS: That was our first reaction.

MR. MOORE: But I told the Chairman about the black smoke.

DR. COVERT: We knew about the black smoke I believe it was last week, but I've lost contact with reality.

CHAIRMAN ROGERS: Joe, I want to be sure to get you an executive jet so you can catch up with us.

[494] Laughter )

MR. SUTTER: I just want to make one more comment. When one of those dumb guys asks what the hell do you think might be the black smoke, we know you guys have got to do a lot of investigation, and the black smoke may be some cigar left in the pipe, but I mean, you




fellows said it may have been the damned rubber tubes. We don't have to worry about the press anymore.

MR. MOORE: Well, we are delighted to have this entire group down here so you can hear firsthand from all of the task force people that have been working this, and you can all see the data that we have seen. This is the latest data that we have seen here, and you are seeing it right now.

So you should be ahead of the world.




DR. WALKER: Jesse, maybe you and a couple of other guys could just have a press conference and present all of this.

MR. MOORE: One suggestion is we were planning to put out some additional data after we had had a chance to brief the Commission here on some of this photography and some other kinds of things, but I wanted to make sure that the Commissioners saw it first hand before we released it.

DR. WALKER: You could have one of these things with a few select people.

MR. MOORE: We also had yesterday Dr. Lucas and Larry Mulloy on a press conference for an hour and a half to try to answer questions.




CHAIRMAN ROGERS: When should you say something about that? I mean, I certainly would be guided by what you think would be best.

MR. MOORE: I think we ought to say something right away about the black smoke.

MR. HARRINGTON: I think the black smoke was




mentioned in the press conference yesterday by the press.

MR. MOORE: I think we ought to release the photos on the black smoke.


MR. MOORE: We don't have any problem with that. I think that is the way we ought to do it. In fact, I believe we ought to put together a press kit with these photos in it, talking about the black smoke and explaining it, and release it to the press.

MR. FEYNMAN: Could I add a suggestion that when you present it you simply say that you have known about this for how many days but you preferred to show it to the Commission completely before you presented it, and that was the only reason for the delay?

DR. WALKER: Or that you wanted to document it properly.

MR. MOORE: My task force has not even seen all of this data.




I think that is what we would like to do.

DR. LUCAS: We admitted yesterday there is black smoke. I had to say truthfully that I had not seen it, because I had not, but we did say that the black smoke had been reported.

[495] CHAIRMAN ROGERS: But it didn't get any attention.

DR. WALKER: I think I saw you make that comment, and they didn't pick up on it.

CHAIRMAN ROGERS: Why don't we do this tonight?

DR. WALKER: Mr. Chairman, I wonder now, from the theories and models that you have, how should they deal with that? One way is just to say we have several theories, and they might want to know what they are.

MR. SUTTER: Well, I would say that they have got several theories, and they expose the theories to the Commission, they are telling the Commission about the tests they are planning, the Commission reviewed their test plans and maybe even augmented them, and they are getting on with the testing.

DR. WALKER: The press is going to want to know the theories.

MR. MOORE: Mr. Chairman, I think we ought to put together a draft press package on this thing, and then I think we ought to get on with our presentation here because you are going to hear some theories associated with O-rings and tank leakage and so forth.

MR. FEYNMAN: Good. Let's go on.

MR. RUMMEL: I might suggest that it would be useful for the Commission and the members to see the press releases of this type so we know what's going to come out.

CHAIRMAN ROGERS: He's been giving it to us. We've had trouble transmitting it to all Commissioners, but we have been getting the documents.

MR. MOORE: We will go off and work something for possible release tonight on these photos. It will not make the evening news. It will be for the morning type of thing.

CHAIRMAN ROGERS: Let's tell them we don't have anything for the evening news.

MR. MOORE: It might make the 11:00 o'clock




news but not the national news because I think we want to get the right photos in there and we want to have the right explanation to go with it.

I would like to introduce Jack Lee who is Deputy Director of the Marshall Space Flight Center.

CHAIRMAN ROGERS: Why don't we take about a five minute recess first?

(A brief recess was taken.)

CHAIRMAN ROGERS: Let's come back to order, okay?


February 11, 1986 SESSION | Volume 4 Index | February 13, 1986 SESSION (part 2)