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
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
points.
[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
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. KOHRS: No.
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?
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
conditions?
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.
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
concern?
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.
CHAIRMAN ROGERS: Okay.
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.
CHAIRMAN ROGERS: Go ahead.
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. KOHRS: Yes.
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. KOHRS: Yes.
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
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. KOHRS: Yes.
MR. WAITE: How is that chamber pressure derived?
MR. KOHRS: We actually have o