Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident


Chapter V: The Contributing Cause of The Accident.



[82] The decision to launch the Challenger was flawed. Those who made that decision were unaware of the recent history of problems concerning the O-rings and the joint and were unaware of the initial written recommendation of the contractor advising against the launch at temperatures below 53 degrees Fahrenheit and the continuing opposition of the engineers at Thiokol after the management reversed its position. They did not have a clear understanding of Rockwell's concern that it was not safe to launch because of ice on the pad. If the decisionmakers had known all of the facts, it is highly unlikely that they would have decided to launch 51-L on January 28, 1986.


Flaws In The Decision Making Process

In addition to analyzing all available evidence concerning the material causes of the accident on January 28, the Commission examined the chain of decisions that culminated in approval of the launch. It concluded that the decision making process was flawed in several ways. The actual events that produced the information upon which the approval of launch was based are recounted and appraised in the sections of this chapter. The discussion that follows relies heavily on excerpts from the testimony of those involved in the management judgments that led to the launch of the Challenger under conditions described.

That testimony reveals failures in communication that resulted in a decision to launch 51-L based on incomplete and sometimes misleading information, a conflict between engineering data and management judgments, and a NASA management structure that permitted internal flight safety problems to bypass key Shuttle managers.

The Shuttle Flight Readiness Review is a carefully planned, step-by-step activity, established by NASA program directive SPO-PD 710.5A, 1 designed to certify the readiness of all components of the Space Shuttle assembly. The process is focused upon the Level I Flight Readiness Review, held approximately two weeks before a launch. The Level I review is a conference chaired by the NASA Associate Administrator for Space Flight and supported by the NASA Chief Engineer, the Program Manager, the center directors and project managers from Johnson, Marshall and Kennedy, along with senior contractor representatives.

The formal portion of the process is initiated by directive from the Associate Administrator for Space Flight. The directive outlines the schedule for the Level I Flight Readiness Review and for the steps that precede it. The process begins at Level IV with the contractors formally certifying-in writing-the flight readiness of the elements for which they are responsible. Certification is made to the appropriate Level III NASA project managers at Johnson and Marshall. Additionally, at Marshall the review is followed by a presentation directly to the Center Director. At Kennedy the Level III review, chaired by the Center Director, verifies readiness of the launch support elements.

The next step in the process is the Certification of Flight Readiness to the Level II Program Manager at Johnson. In this review each Space Shuttle program element endorses that it has satisfactorily completed the manufacture, [83] assembly, test and checkout of the pertinent element, including the contractors" certification that design and performance are up to standard. The Flight Readiness Review process culminates in the Level I review.

In the initial notice of the review, the Level I directive establishes a Mission Management Team for the particular mission. The team assumes responsibility for each Shuttle's readiness for a period commencing 48 hours before launch and continuing through post-landing crew egress and the safing of the Orbiter. On call throughout the entire period, the Mission Management Team supports the Associate Administrator for Space Flight and the Program Manager.

A structured Mission Management Team meeting-called L-1-is held 24 hours, or one day, prior to each scheduled launch. Its agenda includes closeout of any open work, a closeout of any Flight Readiness Review action items, a discussion of new or continuing anomalies, and an updated briefing on anticipated weather conditions at the launch site and at the abort landing sites in different parts of the world. It is standard practice of Level-I and II officials to encourage the reporting of new problems or concerns that might develop in the interval between the Flight Readiness Review and the L-1 meeting, and between the L-1 and launch.

In a procedural sense, the process described...


Readiness reviews for both the launch and the flight of a Shuttle mission are conducting at ascending levels that begin with contractors. Note: See Chart on page 102 for description of management

Readiness reviews for both the launch and the flight of a Shuttle mission are conducting at ascending levels that begin with contractors. Note: See Chart on page 102 for description of management "levels" and organization chain of command.


[84]....was followed in the case of flight 51 -L. However, in the launch preparation for 51-L relevant concerns of Level III NASA personnel and element contractors were not, in the following crucial areas, adequately communicated to the NASA Level I and II management responsible for the launch:

On December 13, 1985, the Associate Administrator for Space flight, Jesse Moore, sent out a message distributed among NASA Headquarters, NASA field centers, and U.S. Air Force units, that scheduled the Flight Readiness Review for January 15, 1986, and prescribed the dates for the other steps in the standard procedure.

The message was followed by directives from James A. (Gene) Thomas, Deputy Director of Launch and Landing Operations at Kennedy on January 2, 1986; by the National Space Transportation System Program Manager, Arnold Aldrich, on January 3; by William R. Lucas, the Marshall Center Director, on January 7; and by the Marshall Shuttle Projects Office on January 8. Each of these implementing directives prescribed for Level III the preparatory steps for the Flight Readiness Review.

The Flight Readiness Review was held, as scheduled, on January 15. On the following day, Aldrich issued the schedule for the combined Level I/Mission Management Team meetings; he also announced plans for the Mission Management Team meetings continuing throughout the mission and included the schedule for the L-1 review.

On January 23, Moore issued a directive stating that the Flight Readiness Review had been conducted on the 15th and that 51-L was ready to fly pending closeout of open work, satisfactory countdown, and completion of remaining Flight Readiness Review action items, which were to be closed out during the L-1 meeting. No problems with the Solid Rocket Booster were identified.

Since December, 1982, the O-rings had been designated a "Criticality 1" feature of the Solid...


The NASA Asscociate Administrator for Space Flight issued this notice of scheduling of the Flight Readiness Review for mission 51-L.

The NASA Asscociate Administrator for Space Flight issued this notice of scheduling of the Flight Readiness Review for mission 51-L.


....Rocket Booster design, a term denoting a failure point-without back-up-that could cause a loss of 'life or vehicle if' the component fails. In July 1985, after a nozzle joint on STS 51-B showed erosion of a secondary O-ring, indicating that the primary seal failed, a launch constraint was placed on flight 51-F and subsequent launches. These constraints had been imposed and regularly waived by the Solid Rocket Booster Project Manager at Marshall, Lawrence B. Mulloy.

Neither the launch constraint, the reason for it, or the six consecutive waivers prior to 51-L were known to Moore (Level I) or Aldrich (Level II) or Thomas at the time of the Flight Readiness Review process for 51-L.

It should be noted that there were other and independent paths of system reporting that were designed to bring forward information about the Solid Rocket Booster joint anomalies. One path was the task force of Thiokol engineers and [85] Marshall engineers who had been conducting subscale pressure tests at Wasatch during 1985, a source of documented rising concern and frustration on the part of some of the Thiokol participants and a few of the Marshall participants. But Level II was not in the line of reporting for this activity. Another path was the examination at each Flight Readiness Review of evidence of earlier flight anomalies. For 51-L, the data presented in this latter path, while it reached Levels I and II, never referred to either test anomalies or flight anomalies with O-rings.

In any event, no mention of the O-ring problems in the Solid Rocket Booster joint appeared in the Certification of Flight Readiness, signed for Thiokol on January 9, 1986, by Joseph Kilminster, for the Solid Rocket Booster set designated BI026.2

Similarly, no mention appeared in the certification endorsement, signed on January 15, 1986, by Kilminster and by Mulloy,3 No mention appears in several inches of paper comprising the entire chain of readiness reviews for 51-L.4

In the 51-L readiness reviews, it appears that neither Thiokol management nor the Marshall Level III project managers believed that the O-ring blow-by and erosion risk was critical. The testimony and contemporary correspondence show that Level III believed there was ample margin to fly with O-ring erosion, provided the leak check was performed at 200 pounds per square inch.

Following the January 15 Flight Readiness Review each element of the Shuttle was certified as flight-ready.

The L- 1 Mission Management Team meeting took place as scheduled at 11:00 a.m. Eastern Standard Time January 25. No technical issues appeared at this meeting or in the documentation and all Flight Readiness Review actions were reported closed out.

Mr. Mulloy testified as follows regarding the Flight Readiness Review record about O-ring concerns: 5


Chairman Rogers: . . . Why wasn't that a cause for concern on the part of the whole NASA organization?

Mr. Mulloy: It was cause for concern, sir.

Chairman Rogers: Who did you tell about this?

Mr. Mulloy: Everyone, sir.

Chairman Rogers: And they all knew about it at the time of 51-L?

Mr. Mulloy: Yes, sir. You will find in the Flight Readiness Review record that went all the way to the L-1 review.


It is disturbing to the Commission that contrary to the testimony of the Solid Rocket Booster Project Manager, the seriousness of concern was not conveyed in Flight Readiness Review to Level I and the 51-L readiness review was silent.

The only remaining issue facing the Mission Management Team at the L-1 review was the approaching cold front, with forecasts of rain showers and temperatures in the mid-sixties. There had also been heavy rain since 51-L had been rolled out to the launch pad, approximately seven inches compared with the 2.5 inches that would have been normal for that season and length of exposure (35 days).

At 12:36 p.m. on the 27th, the Mission Management Team scrubbed the launch for that day due to high cross winds at the launch site. In the accompanying discussion that ran for about half an hour, all appropriate personnel were polled as to the feasibility of a launch within 24 hours. Participants were requested to identify any constraints. This meeting, aimed at launch at 9:38 a.m. On January 28, produced no constraints or concerns about the performance of the Solid Rocket Boosters.

At 2:00 p.m. on the 27th, the Mission Management Team met again. At that time, the weather was expected to clear, but it appeared that temperatures would be in the low twenties for about 11 hours. Issues were raised with regard to the cold weather effects on the launch facility, including the water drains, the eye wash and shower water, fire suppression system, and overpressure water trays. It was decided to activate heaters in the Orbiter, but no concerns were expressed about the O-rings in the Solid Rocket Boosters. The decision was to proceed with the countdown and with fueling, but all members of the team were asked to review the situation and call if any problems arose.

At approximately 2:30 p.m. EST, at Thiokol's Wasatch plant, Robert Ebeling, after learning of the predicted low temperature for launch, convened a meeting with Roger Boisjoly and with other Thiokol engineers. A brief chronology of the subsequent chain of events begins on page 104. Ebeling was concerned about predicted cold [86] temperatures at Kennedy Space Center. In a post-accident interview, Mr. Ebeling recalled the substance of the meeting. 6

"The meeting lasted one hour, but the conclusion of that meeting was Engineering-especially Arnie, Roger Boisjoly, Brian Russell, myself, Jerry Burns, they come to mind-were very adamant about their concerns on this lower temperature, because we were way below our data base and we were way below what we qualified for."

Later in the afternoon on the same day, Allan McDonald-Thiokol's liaison for the Solid Rocket Booster project at Kennedy Space Center- received a telephone call from Ebeling, expressing concern about the performance of the Solid Rocket Booster field joints at low temperatures. During testimony before the Commission on February 27, McDonald recounted that conversation:7


Mr. McDonald: Well, I had first become aware of the concern of the low temperatures that were projected for the Cape, it was late in the afternoon of the 27th. I was at Carver Kennedy's house. He is a vice president of, as I mentioned, our space operations center at the Cape, and supports the stacking of the SRMs [Solid Rocket Motors].

And I had a call from Bob Ebeling. He is the manager of our ignition system an final assembly, and he worked for me as program manager at Thiokol in Utah. And he called me and said that they had just received some word earlier that the weatherman was projecting temperatures as low as 18 degrees Fahrenheit some time in the early morning hours of the 28th, and that they had some meetings with some of the engineering people and had some concerns about the O-rings getting to those kinds of temperatures.

And he wanted to make me aware of that and also wanted to get some more updated and better information on what the actual temperature was going to be depicted, so that they could make some calculations on what they expected the real temperature the O-rings may see....

I told him that I would get that temperature data for him and call him back. Carver Kennedy then, when I hung up, called the launch operations center to get the predicted temperatures from pad B, as well as what the temperature history had been during the day up until that time.

. . . He obtained those temperatures from the launch operations center, and they basically said that they felt it was going to get near freezing or freezing before midnight. It would get as low as 22 degrees as a minimum in the early morning hours, probably around 6:00 o'clock, and that they were predicting a temperature of about 26 degrees at the intended time, about 9:38 the next morning.

I took that data and called back to the plant and sent it to Bob Ebeling and relayed that to him, and told him he ought to use this temperature data for his predictions, but I thought this was very serious and to make sure that he had the vice president, engineering, involved in this and all of his people; that I wanted them to put together some calculations and a presentation of material.

Chairman Rogers: Who's the Vice President, Engineering?

Mr. McDonald: Mr. Bob Lund is our Vice President, Engineering, at our Morton Thiokol facility in Utah.

To make sure he was involved in this, and that this decision should be an engineering decision, not a program management decision. And I told him that I would like him to make sure they prepared some charts and were in a position to recommend the launch temperature and to have the rationale for supporting that launch temperature.

I then hung up and I called Mr. Mulloy. He was staying at the Holiday Inn in Merritt Island and they couldn't reach him, and so I called Cecil Houston-Cecil Houston is the resident manager for the Marshall Space Flight Center office at KSC [Kennedy Space Center]-and told him about our concerns with the low temperatures and the potential problem with the O-rings.

And he said that he would set up a teleconference. He had a four-wire system next to his office. His office is right across from the VAB [Vehicle Assembly Building] in the trailer complex C over there. And he would set up a four-wire teleconference involving the engineering people at Marshall Space Flight Center at Huntsville, our people back at Thiokol in Utah; and that I [87] should come down to his office and participate at Kennedy from there, and that he would get back with me and let me know when that time would be.


Soon thereafter Cecil Houston called Dr. Judson Lovingood, Deputy Shuttle Project Manager at Marshall Space Flight Center, to inform him of the concerns about the O-rings and asked Lovingood to set up a teleconference with senior project management personnel, with George Hardy, Marshall's Deputy Director of Science and Engineering, and with Morton Thiokol personnel. Lovingood called Stanley Reinartz, Shuttle Project Manager, a few minutes later and informed him of the planned telecon.

The first phase of the teleconference began at 5:45 p. m. Eastern Standard Time; participants included Reinartz, Lovingood, Hardy, and numerous people at Kennedy, Marshall and Thiokol-Wasatch. (Allen McDonald missed this phase; he did not arrive at Kennedy until after 8:00 p.m.) Concerns for the effect of low temperature on the O-rings and the joint seal were presented by Morton Thiokol, along with an opinion that launch should be delayed. A recommendation was also made that Aldrich, Program Manager at Johnson (Level II), be informed of these concerns.

The following are excerpts from testimony before the Commission relating to the teleconference: 8


Dr. Keel: You just indicated earlier that, based upon that teleconference, you thought there was a good possibility of delay. Is that what Thiokol was recommending then, was delay?

Dr. Lovingood: That is the way I heard it, and they were talking about the 51-C experience and the fact that they had experienced the worst case blow-by as far as the arc and the soot and so forth. And also, they talked about the resiliency data that they had.

So it appeared to me-and we didn't have all of the proper people there. That was another aspect of this. It appeared to me that we had better sit down and get the data so that we could understand exactly what they were talking about and assess that data.

And that is why I suggested that we go ahead and have a telecon within the center, so that we could review that.

Dr. Keel: So as early as after that first afternoon conference at 5:45, it appeared that Thiokol was basically saying delay. Is that right?

Dr. Lovingood: That is the way it came across to me. I don't know how other people perceived it, but that's the way it came across to me.

Dr. Keel: Mr. Reinartz, how did you perceive It?

Mr. Reinartz: I did not perceive it that way. I perceived that they were raising some questions and issues which required looking into by all the right parties, but I did not perceive it as a recommendation delay.

Dr. Keel: Some prospects for delay?

Mr. Reinartz: Yes, sir, that possibility is always there.

Dr. Keel: Did you convey that to Mr. Mulloy and Mr. Hardy before the 8:15 conference?

Mr. Reinartz: Yes, I did. And as a matter of fact, we had a discussion. Mr. Mulloy was just out of communication for about an hour, and then after that I got in contact with him, and we both had a short discussion relating to the general nature of the concerns with Dr. Lucas and Mr. Kingsbury at the motel before we both departed for the telecon that we had set up out at the Cape.

Dr. Keel: But based upon that, Mr. Lovingood, that impression, you thought it was a significant enough possibility that Mr. Aldrich should have been contacted?

Dr. Lovingood: Yes.

Dr. Keel: In addition, did you recommend that Mr. Lucas, who is director of Marshall, of course, and Mr. Kingsbury, who is Mr. Hardy's boss, participate in the 8:15 conference?

Dr. Lovingood: Yes, I did.

Dr. Keel: And you recommended that to whom?

Dr. Lovingood: I believe I said that over the net. I said that I thought we ought to have an inter-center meeting involving Dr. Lucas and Mr. Kingsbury, and then plan to go on up the line to Level II and Level I.

And then it was after we broke off that first telecon I called Stan at the motel and told [88] him that he ought to go ahead and alert Arnie to that possibility.

Dr. Keel: And Mr. Reinartz, you then visited the motel room of Mr. Lucas with Mr. Kingsbury, and also was Mr. Mulloy with you then?

Mr. Reinartz: Yes, sir, he was. In the first couple of minutes I believe I was there by myself, and then Mr. Mulloy joined us.

Dr. Keel: And did you discuss with them Mr. Lovingood's recommendation that the two of them, Lucas and Kingsbury, participate?

Mr. Reinartz: No, sir. I don't recall discussing Mr. Lovingood's recommendations. I discussed with them the nature of the telecon, the nature of the concerns raised by Thiokol, and the plans to gather the proper technical support people at Marshall for examination of the data. And I believe that was the essence of the discussion.

Chairman Rogers: But you didn't recommend that the information be given to Level II or Level I?

Mr. Reinartz: I don't recall that I raised that issue with Dr. Lucas. I told him what the plans were for proceeding. I don't recall, Mr. Chairman, making any statement regarding that.

Mr. Hotz: Mr. Reinartz, are you telling us that you in fact are the person who made the decision not to escalate this to a Level II item?

Mr. Reinartz: That is correct, sir.


At approximately 8:45 p.m. Eastern Standard Time, Phase 2 of the teleconference commenced, the Thiokol charts and written data having arrived at Kennedy Space Center by telefax. (A table of teleconference participants is included with Chronology of Events.) The charts presented a history of the O-ring erosion and blow-by in the Solid Rocket Booster joints of previous flights, presented the results of subscale testing at Thiokol and the results of static tests of Solid Rocket Motors. In the following testimony, Roger Boisjoly, Allan McDonald and Larry Mulloy expressed their recollections of this teleconference up to the point when an off-net caucus was requested: 9


Mr. Boisjoly: I expressed deep concern about launching at low temperature. I presented Chart 2-1 with emphasis-now, 2-1, if you want to see it, I have it, but basically that was the chart that summarized the primary concerns, and that was the chart that I pulled right out of the Washington presentation without changing one word of it because it was still applicable, and it addresses the highest concern of the field joint in both the ignition transient condition and the steady state condition, and it really sets down the rationale for why we were continuing to fly. Basically, if erosion penetrates the primary O-ring seal, there is a higher probability of no secondary seal capability in the steady state condition. And I had two sub-bullets under that which stated bench testing showed O-ring not capable of maintaining contact with metal parts, gap, opening rate to maximum operating pressure. I had another bullet which stated bench testing showed capability to maintain O-ring contact during initial phase (0 to 170 milliseconds of transient). That was my comfort basis of continuing to fly under normal circumstances, normal being within the data base we had.

I emphasized, when I presented that chart about the changing of the timing function of the O-ring as it attempted to seal. I was concerned that we may go from that first beginning region into that intermediate region, from O to 170 being the first region, and 170 to 330 being the intermediate region where we didn't have a high probability of sealing or seating.

I then presented Chart 2-2 with added concerns related to the timing function. And basically on that chart, I started off talking about a lower temperature than current data base results in changing the primary O-ring sealing timing function, and I discussed the SRM-15 [Flight 51-C, January, 1985] observations, namely, the 15A [Left SRM, Flight 51-C] motor had 80 degrees arc black grease between the O-rings, and make no mistake about it, when I say black, I mean black just like coal. It was jet black. And SRM-15B [Right SRM, Flight 51-C] had a 110 degree arc of black grease between the O-rings. We would have low O-ring squeeze due to low.....


Chart 2-1 [Left] presented by Thiokol's Roger Boisjoly summarizing primary concerns with the field joint and its O-ring seals on the boosters.

Boisjoly's Chart 2-2 [Right] indicating concern about temperature effect on seal actuation time (handwritten).

Chart 2-1 [Left] presented by Thiokol's Roger Boisjoly summarizing primary concerns with the field joint and its O-ring seals on the boosters.

Boisjoly's Chart 2-2 [Right] indicating concern about temperature effect on seal actuation time (handwritten).


[89] ....temperature which I calculated earlier in the day. We should have higher O-ring Shore hardness.

Now, that would be harder. And what that material really is, it would be likened to trying to shove a brick into a crack versus a sponge. That is a good analogy for purposes of this discussion. I also mentioned that thicker grease, as a result of lower temperatures, would have a higher viscosity. It wouldn't be as slick and slippery as it would be at room temperature. And so it would be a little bit more difficult to move across it.

We would have higher O-ring pressure actuation time, in my opinion, and that is what I presented.... These are the sum and substance of what I just presented. If action time increases, then the threshold of secondary seal pressurization capability is approached. That was my fear. If the threshold is reached, then secondary seal may not be capable of being pressurized, and that was the bottom line of everything that had been presented up to that point.

Chairman Rogers: Did anybody take issue with you?

Mr. Boisjoly: Well, I am coming to that. I also showed a chart of the joint with an exaggerated cross section to show the seal lifted off, which has been shown to everybody. I was asked, yes, at that point in time I was asked to quantify my concerns, and I said I couldn't. I couldn't quantify it. I had no data to quantify it, but I did say I knew that it was away from goodness in the current data base. Someone on the net commented that we had soot blow-by on SRM-22 [Flight 61-A, October, 1985] which was launched at 75 degrees. I don't remember who made the comment, but that is where the first comment came in about the disparity between my conclusion and the observed data because SRM-22 [Flight 61-A, October, 1985] had blow-by at essentially a room temperature launch.

I then said that SRM-15 [Flight 51-C, January, 1985] had much more blow-by indication and that it was indeed telling us that lower temperature was a factor. This was supported by inspection of flown hardware by myself. I was asked again for data to support my claim, and I said I have none other than what is being presented, and I had been trying to get resilience data, Arnie and I both, since last October, and that statement was mentioned on the net.

Others in the room presented their charts, and the main telecon session concluded with Bob Lund, who is our Vice President of....


Initial Thikol recommendation Chart presented by Robert K. Lund at second teleconference prior to Thiolol caucus.

Initial Thikol recommendation Chart presented by Robert K. Lund at second teleconference prior to Thiolol caucus.


[90] ....Engineering, presenting his conclusions and recommendations charts which were based on our data input up to that point. Listeners on the telecon were not pleased with the conclusions and the recommendations.

Chairman Rogers: What was the conclusion ?

Mr. Boisjoly: The conclusion was we should not fly outside of our data base, which was 53 degrees. Those were the conclusions. And we were quite pleased because we knew in advance, having participated in the preparation, what the conclusions were, and we felt very comfortable with that.

Mr. Acheson: Who presented that conclusion?

Mr. Boisjoly: Mr. Bob Lund. He had prepared those charts. He had input from other people. He had actually physically prepared the charts. It was about that time that Mr. Hardy from Marshall was asked what he thought about the MTI [Morton Thiokol] recommendation, and he said he was appalled at the MTI decision. Mr. Hardy was also asked about launching, and he said no, not if the contractor recommended not launching, he would not go against the contractor and launch.

There was a short discussion that ensued about temperature not being a discriminator between SRM-15 [Flight 51-C] and SRM-22 [Flight 61-A], and shortly after, I believe it was Mr. Kilminster asked if- excuse me. I'm getting confused here. Mr. Kilminster was asked by NASA if he would launch, and he said no because the engineering recommendation was not to launch.

Then MTI management then asked for a five-minute caucus. I'm not sure exactly who asked for that, but it was asked in such a manner that I remember it was asked for, a five-minute caucus, which we put on- the line on mute and went off-line with the rest of the net.

Chairman Rogers: Mr. Boisjoly, at the time that you made the-that Thiokol made the recommendation not to launch, was that the unanimous recommendation as far as you knew?

Mr. Boisjoly: Yes. I have to make something clear. I have been distressed by the things that have been appearing in the paper and things that have been said in general, and there was never one positive, pro-launch statement ever made by anybody. There have been some feelings since then that folks have expressed that they would support the decision, but there was not one positive statement for launch ever made in that room.


Mr. McDonald's testimony: 10


Mr. McDonald: I arrived at the Kennedy Space Center at about 8:15 [p.m.], and when I arrived there at the Kennedy Space Center the others that had already arrived were Larry Mulloy, who was there-he is the manager, the project manager for the SRB for Marshall. Stan Reinartz was there and he is the manager of the Shuttle Project Office. He's Larry Mulloy's boss.

Cecil Houston was there, the resident manager for Marshall. And Jack Buchanan was there. He happens to be our manager, Morton Thiokol's manager of our launch support services office at Kennedy.

The telecon hadn't started yet. It came on [91] the network shortly after I got there. .

Chairman Rogers: Was it essentially a telephone conference or was there actually a network of pictures?

Mr. McDonald: It was a telephone conference....

But I will relay . . . what I heard at the conference as best I can. The teleconference started I guess close to 9:00 o'clock and, even though all the charts weren't there, we were told to begin and that Morton Thiokol should take the lead and go through the charts that they had sent to both centers.

The charts were presented by the engineering people from Thiokol, in fact by the people that had made those particular charts. Some of them were typed, some of them were handwritten. And they discussed their concerns with the low temperatures relative to the possible effects on the O-rings, primarily the timing function to seal the 0rings.

They presented a history of some of the data that we had accumulated both in static test and in flight tests relative to temperatures and the performance of the 0rings, and reviewed the history of all of our erosion studies of the O-rings, in the field joints, any blow-by of the primary O-ring with soot or products of combustion or decomposition that we had noted, and the performance of the secondary O-rings.

And there was an exchange amongst the technical people on that data as to what it meant . . . But the real exchange never really came until the conclusions and recommendations came in.

At that point in time, our vice president, Mr. Bob Lund, presented those charts and he presented the charts on the conclusions and recommendations. And the bottom line was that the engineering people would not recommend a launch below 53 degrees Fahrenheit. The basis for that recommendation was primarily our concern with the launch that had occurred about a year earlier, in January of 1985, I believe it was 51-C.


Mr. Mulloy's testimony: 11


Mr. Mulloy: That telecon was a little late starting. It was intended to be set up at 8:15 . . . and the telecon was begun at 8:45.

And Thiokol will then present to you today the data that they presented to us in that telecon. I will not do that. The bottom line of that, though, initially was that Thiokol engineering, Bob Lund, who is the Vice President and Director of Engineering, who is here today, recommended that 51-L not be launched if the O-ring temperatures predicted at launch time would be lower than any previous launch, and that was 53 degrees.

Dr. Walker: May I ask a question? I wish you would distinguish between the predicted bulk temperatures and the O-ring temperatures. In fact, as I understand it, you really don't have any official O-ring temperature prediction in your models, and it seems that the assumption has been that the O-ring temperature is the same as the bulk temperature, which we know is not the case.

Mr. Mulloy: You will see, sir, in the Thiokol presentation today that that is not the case. This was a specific calculation of what the O-ring temperature was on the day of the January 1985 launch. It is not the bulk temperature of the propellant, nor is it the ambient temperature of the air.

It was Thiokol's calculation of what the lowest temperature an O-ring had seen in previous flights, and the engineering recommendation was that we should not move outside of that experience base.

I asked Joe Kilminster, who is the program manager for the booster program at Thiokol, what his recommendation was, because he is the gentleman that I get my recommendations from in the program office. He stated that, based on that engineering recommendation, that he could not recommend launch.

At that point I restated, as I have testified to, the rationale that was essentially documented in the 1982 Critical Items List, that stated that the rationale had been that we were flying with a simplex joint seal. And you will see in the Thiokol presentation that the context of their presentation is that the primary ring, with the reduced temperatures and reduced resiliency, may not function as [92] a primary seal and we would be relying on secondary.

And without getting into their rationale and getting ahead, the point, the bottom line, is that we were continuing-the assessment was, my assessment at that time was, that we would have an effective simplex seal, based upon the engineering data that Thiokol had presented, and that none of those engineering data seemed to change that basic rationale.

Stan Reinartz then asked George Hardy, the Deputy Director of Science and Engineering at Marshall, what his opinion was. George stated that he agreed that the engineering data did not seem to change this basic rationale, but also stated on the telecon that he certainly would not recommend launching if Thiokol did not.

At that time Joe Kilminster requested a five minute off-net caucus, and that caucus lasted approximately 30 minutes.


The teleconference was recessed at approximately 10:30 p.m. Eastern Standard Time. The off-net caucus of Thiokol personnel started and continued for about 30 minutes at the Wasatch office. The major issues, according to the testimony of Jerry Mason, Senior Vice President for Wasatch Operations, were the effect of temperature upon the O-rings and the history of erosion of the O-rings: 12


Mr. Mason: Now, in the caucus we revisited all of our previous discussions, and the important things that came out of that was that, as we had recognized, we did have the possibility that the primary O-ring might be slower to move into the seating position and that was our concern, and that is what we had focused on originally.

The fact that we couldn't show direct correlation with the O-ring temperature was discussed, but we still felt that there was some concern about it being colder.

We then recognized that, if the primary did move more slowly, that we could get some blow-by and erosion on the primary. But we had pointed out to us in that caucus a point that had not come across clearly in our earlier discussions, and that is that we had run tests where we deliberately cut large pieces out of the O-rings to see what the threshold of sealing was, and we found we could go to 125 thousandths of a cut out of the O-ring and it would still seal.


Approximately 10 engineers participated in the caucus, along with Mason, Kilminster, C. G. Wiggins (Vice President, Space Division), and Lund. Arnold Thompson and Boisjoly voiced very strong objections to launch, and the suggestion in their testimony was that Lund was also reluctant to launch:13


Mr. Boisjoly: Okay, the caucus started by Mr. Mason stating a management decision was necessary. Those of us who opposed the launch continued to speak out, and I am specifically speaking of Mr. Thompson and myself because in my recollection he and I were the only ones that vigorously continued to oppose the launch. And we were attempting to go back and rereview and try to make clear what we were trying to get across, and we couldn't understand why it was going to be reversed. So we spoke out and tried to explain once again the effects of low temperature. Arnie actually got up from his position which was down the table, and walked up the table and put a quarter pad down in front of the table, in front of the management folks, and tried to sketch out once again what his concern was with the joint, and when he realized he wasn't getting through, he just stopped.

I tried one more time with the photos. I grabbed the photos, and I went up and discussed the photos once again and tried to make the point that it was my opinion from actual observations that temperature was indeed a discriminator and we should not ignore the physical evidence that we had observed .

And again, I brought up the point that SRM- 15 [Flight 51 -C, January, 1985] had a 110 degree arc of black grease while SRM-22 [Flight 61-A, October, 1985] had a relatively different amount, which was less and wasn't quite as black. I also stopped when it was apparent that I couldn't get anybody to listen.

Dr. Walker: At this point did anyone else speak up in favor of the launch?

Mr. Boisjoly: No, sir. No one said anything, in my recollection, nobody said a word. It was then being discussed amongst the management folks. After Arnie and I had [93] our last say, Mr. Mason said we have to make a management decision. He turned to Bob Lund and asked him to take off his engineering hat and put on his management hat. From this point on, management formulated the points to base their decision on. There was never one comment in favor, as I have said, of launching by any engineer or other nonmanagement person in the room before or after the caucus. I was not even asked to participate in giving any input to the final decision charts.

I went back on the net with the final charts or final chart, which was the rationale for launching, and that was presented by Mr. Kilminster. It was hand written on a notepad, and he read from that notepad. I did not agree with some of the statements that were being made to support the decision. I was never asked nor polled, and it was clearly a management decision from that point.

I must emphasize, I had my say, and I never [would] take [away] any management right to take the input of an engineer and then make a decision based upon that input, and I truly believe that. I have worked at a lot of companies, and that has been done from time to time, and I truly believe that, and so there was no point in me doing anything any further than I had already attempted to do.

I did not see the final version of the chart until the next day. I just heard it read. I left the room feeling badly defeated, but I felt I really did all I could to stop the launch.

I felt personally that management was under a lot of pressure to launch and that they made a very tough decision, but I didn't agree with it.

One of my colleagues that was in the meeting summed it up best. This was a meeting where the determination was to launch, and it was up to us to prove beyond a shadow of a doubt that it was not safe to do so. This is in total reverse to what the position usually is in a preflight conversation or a flight readiness review. It is usually exactly opposite that.

Dr. Walker: Do you know the source of the pressure on management that you alluded to?

Mr. Boisjoly: Well, the comments made over the [net] is what I felt, I can't speak for them, but I felt it-I felt the tone of the meeting exactly as I summed up, that we were being put in a position to prove that we should not launch rather than being put in the position and prove that we had enough data to launch. And I felt that very real.

Dr. Walker: These were the comments from the NASA people at Marshall and at Kennedy Space Center? Mr. Boisjoly: Yes. Dr. Feynman: I take it you were trying to find proof that the seal would fail?

Mr. Boisjoly: Yes.

Dr. Feynman: And of course, you didn't, you couldn't, because five of them didn't, and if you had proved that they would have all failed, you would have found yourself incorrect because five of them didn't fail.

Mr. Boisjoly: That is right. I was very concerned that the cold temperatures would change that timing and put us in another regime, and that was the whole basis of my fighting that night.


As appears from the foregoing, after the discussion between Morton Thiokol management and the engineers, a final management review was conducted by Mason, Lund, Kilminster, and Wiggins. Lund and Mason recall this review as an unemotional, rational discussion of the engineering facts as they knew them at that time; differences of opinion as to the impact of those facts, however, had to be resolved as a judgment call and therefore a management decision. The testimony of Lund taken by Commission staff investigators is as follows: 14


Mr. Lund: We tried to have the telecon, as I remember it was about 6:00 o'clock [MST], but we didn't quite get things in order, and we started transmitting charts down to Marshall around 6:00 or 6:30 [MST], something like that, and we were making charts in real time and seeing the data, and we were discussing them with the Marshall folks who went along.

We finally got the-all the charts in, and when we got all the charts in I stood at the board and tried to draw the conclusions that we had out of the charts that had been presented, and we came up with a conclusions [94] chart and said that we didn't feel like it was a wise thing to fly.

Question: What were some of the conclusions?

Mr. Lund: I had better look at the chart. Well, we were concerned the temperature was going to be lower than the 50 or the 53 that had flown the previous January, and we had experienced some blow-by, and so we were concerned about that, and although the erosion on the O-rings, and it wasn't critical, that, you know, there had obviously been some little puff go through. It had been caught.

There was no real extensive erosion of that O-ring, so it wasn't a major concern, but we said, gee, you know, we just don't know how much further we can go below the 51 or 53 degrees or whatever it was. So we were concerned with the unknown. And we presented that to Marshall, and that rationale was rejected. They said that they didn't accept that rationale, and they would like us to consider some other thoughts that they had had.

....Mr. Mulloy said he did not accept that, and Mr. Hardy said he was appalled that we would make such a recommendation. And that made me ponder of what I'd missed, and so we said, what did we miss, and Mr. Mulloy said, well, I would like you to consider these other thoughts that we have had down here. And he presented a very strong and forthright rationale of what they thought was going on in that joint and how they thought that the thing was happening, and they said, we'd like you to consider that when they had some thoughts that we had not considered.

.....So after the discussion with Mr. Mulloy, and he presented that, we said, well, let's ponder that a little bit, so we went offline to talk about what we-

Question: Who requested to go off-line?

Mr. Lund: I guess it was Joe Kilminster.

And so we went off line on the telecon . . . so we could have a roundtable discussion here.

Question: Who were the management people that were there?

Mr. Lund: Jerry Mason, Cal Wiggins, Joe, I, manager of engineering design, the manager of applied mechanics. On the chart.


Before the Commission on February 25, 1986, Mr. Lund testified as follows regarding why he changed his position on launching Challenger during the management caucus when he was asked by Mr. Mason "To take off his engineering hat and put on his management hat": 15


Chairman Rogers: How do you explain the fact that you seemed to change your mind when you changed your hat?

Mr. Lund: I guess we have got to go back a little further in the conversation than that. We have dealt with Marshall for a long time and have always been in the position of defending our position to make sure that we were ready to fly, and I guess I didn't realize until after that meeting and after several days that we had absolutely changed our position from what we had been before. But that evening I guess I had never had those kinds of things come from the people at Marshall. We had to prove to them that we weren't ready, and so we got ourselves in the thought process that we were trying to find some way to prove to them it wouldn't work, and we were unable to do that. We couldn't prove absolutely that that motor wouldn't work.

Chairman Rogers: In other words, you honestly believed that you had a duty to prove that it would not work?

Mr. Lund: Well, that is kind of the mode we got ourselves into that evening. It seems like we have always been in the opposite mode. I should have detected that, but I did not, but the roles kind of switched. .


Supplemental testimony of Mr. Mason obtained in a Commission staff interview is as follows: 16


Question: Do you recall Mr. Hardy and Mr. Mulloy's comments after-I think after Mr. Kilminster had got done, or Mr. Lund got done presenting the charts? They had some comments. Do you recall-

Mr. Mason: Oh, yes, it was over and over. Hardy said that, "I'm appalled at your recommendation. ".

Question: Well, did Mr. Hardy's n «appalled" remark and Mr. Mulloy's "can't launch, we won't be able to launch until April" [95] remark, how did that affect your thinking and affect your decision?

Mr. Mason: My personal thinking, I just, you know, it didn't make that much difference .

And the comments that they made, in my view, probably had got more reaction from the engineer[s] at the lower level than they would from the manager[s], because we deal with people, and managers all the time....


Mr. McDonald indicated that during the period of the internal Morton Thiokol caucus he continued to argue for delay with Mulloy, challenging, among other things, the rationale that the rocket motor was qualified down to 40 degrees Farhenheit. Present were Reinartz, Jack Buchanan, the manager of Morton Thiokol Launch Support Services at Kennedy, and Cecil Houston. McDonald's testimony described that conversation: 17


Mr. McDonald: . . . while they were offline, reevaluating or reassessing this data . . . I got into a dialogue with the NASA people about such things as qualification and launch commit criteria.

The comment I made was it is my understanding that the motor was supposedly qualified to 40 to 90 degrees.

I've only been on the program less than three years, but I don't believe it was. I don't believe that all of those systems, elements, and subsystems were qualified to that temperature.

And Mr. Mulloy said well, 40 degrees is propellant mean bulk temperature, and we're well within that. That is a requirement. We're at 55 degrees for that-and that the other elements can be below that . . . that, as long as we don't fall out of the propellant mean bulk temperature. I told him I thought that was asinine because you could expose that large Solid Rocket Motor to extremely low temperatures-I don't care if it's 100 below zero for several hours-with that massive amount of propellant, which is a great insulator, and not change that propellant mean bulk temperature but only a few degrees, and I don't think the spec really meant that.

But that was my interpretation because I had been working quite a bit on the filament wound case Solid Rocket Motor. It was my impression that the qualification temperature was 40 to 90, and I knew everything wasn't qualified to that temperature, in my opinion. But we were trying to qualify that case itself at 40 to 90 degrees for the filament wound case.

I then said I may be naive about what generates launch commit criteria, but it was my impression that launch commit criteria was based upon whatever the lowest temperature, or whatever loads, or whatever environment was imposed on any element or subsystem of the Shuttle. And if you are operating outside of those, no matter which one it was, then you had violated some launch commit criteria.

That was my impression of what that was. And I still didn't understand how NASA could accept a recommendation to fly below 40 degrees. I could see why they took issue with the 53, but I could never see why they would . . . of accept a recommendation below 40 degrees, even though I didn't agree that the motor was fully qualified to 40. I made the statement that if we're wrong and something goes wrong on this flight, I wouldn't want to have to be the person to stand up in front of board of inquiry and say that I went ahead and told them to go ahead and fly this thing outside what the motor was qualified to.

I made that very statement.


Mr. Mulloy's recollections of these discussion are as follows: 18


Mr. Mulloy: Mr. Kilminster then requested an off-net caucus. It has been suggested, implied, or stated that we directed Thiokol to go reconsider these data. That is not true. Thiokol asked for a caucus so that they could consider the discussions that had ensued and the comments that Mr. Hardy and I and others had made.

That caucus, as has been stated, was going to start at that point, and Mr. McDonald interjected into the teleconference. At that point, he made the first comment that he had made during this entire teleconference.

Mr. McDonald testified for quite a while yesterday about his thoughts on this, but he did not say any of them until this point. At that point, he stated that he thought what George Hardy said was a very important [96] consideration, and that consideration was, and he asked Mr. Kilminster to be sure and consider the comment made by George Hardy during the course of the discussions, that the concerns expressed were for primary O-ring blow-by and that the secondary O-ring was in a position to seal during the time of blow-by and would do so before significant joint rotation had occurred.

They then went into their caucus, having asked for five minutes-

Mr. Hotz: . . . It figures quite prominently in the discussion that you were quoted as saying, do you expect us to wait till April to launch?

Mr. Mulloy: Yes, sir.

Dr. Walker: Is that an accurate statement or not?

Mr. Mulloy: It is certainly a statement that is out of context, and the way I read the quote, sir-and I have seen it many times, too many times-the quote I read was: My God, Thiokol, when do you want me to launch, next April?

Mr. McDonald testified to another quote that says: You guys are generating new Launch Commit Criteria.

Now, both of those I think kind of go together, and that is what I was saying. I don't know whether that occurred during the caucus or subsequent to. I just simply can't remember that.

Mr. Hotz: Well, never mind the timing.

Mr. Mulloy: Well, yes, sir. I'm going to answer your question now. I think those quotes derive from a single thought that may have been expressed by me using some of those words.

I have not yet encountered anyone other than those at KSC who heard those words, so I don't believe they were transmitted over the net. The total context I think in which those words may have been used is, there are currently no Launch Commit Criteria [LCC] for joint temperature. What you are proposing to do is to generate a new Launch Commit Criteria on the eve of launch, after we have successfully flown with the existing Launch Commit Criteria 24 previous times. With this LCC, i.e., do not launch with a temperature greater [sic] than 53 degrees, we may not be able to launch until next April. We need to consider this carefully before we jump to any conclusions.

It is all in the context, again, with challenging your interpretation of the data, what does it mean and is it logical, is it truly logical that we really have a system that has to be 53 degrees to fly?


At approximately 11 p.m. Eastern Standard Time, the Thiokol/NASA teleconference resumed, the Thiokol management stating that they had reassessed the problem, that the temperature effects were a concern, but that the data were admittedly inconclusive. Kilminster read the rationale recommending launch and stated that that was Morton Thiokol's recommendation. Hardy requested that it be sent in writing by telefax both to Kennedy and to Marshall, and it was. The testimony of Mulloy and Hardy regarding the remainder of the teleconference and their rationale for recommending launch follows: 19


Mr. Mulloy: Okay, sir. At the completion of the caucus, of course, Mr. Kilminster came back on the loop and stated they had assessed all the data and considered the discussions that had ensued for the past couple of hours and the discussions that occurred during their caucus.

Chairman Rogers: Was it a couple of hours?

Mr. Mulloy: Yes, sir. We started at 8:45 and I believe it was probably 11:00 o'clock before he came back on the loop. It was a long discussion. And I must emphasize that I had no knowledge of what interchange occurred during the caucus at Thiokol, because all sites were on mute. We were on mute at KSC. No communications occurred between myself and Mr. Hardy at Huntsville, nor did any communication occur between KSC and Thiokol during that caucus.

After Mr. Kilminster made that recommendation, Mr. Reinartz then asked if there were any further comments, and to my recollection there were none. There were no further comments made.

I then asked Mr. Kilminster to send me a copy of his flight readiness rationale and recommendation. The conference was then terminated at approximately 11:15.

I have no knowledge of, as has been testified, of Mr. McDonald being asked to sign that documentation. That would have....



Copy of telefax sent Kennedy and Marshall centers by Thiokol detailing the company's final position on the January 28 launch of mission 51-L.

Copy of telefax sent Kennedy and Marshall centers by Thiokol detailing the company's final position on the January 28 launch of mission 51-L.


....been unusual, because Mr. Kilminster signs all flight readiness documentation.

Now, after the teleconference was complete, Mr. McDonald informed Mr. Reinartz and me that if the Thiokol engineering concern for the effect of cold was not sufficient cause to recommend not launching, there were two other considerations, launch pad ice and recovery area weather.

I stated that launch pad ice had been considered by the Mission Management Team-

Chairman Rogers: Excuse me. Could you identify that discussion, where that took place?

Mr. Mulloy: That was after the teleconference was completed, after Mr. Kilminster made his recommendation, after Mr. Reinartz asked are there any other comments. There were no other comments on the telecon from anyone....

I stated that launch pad ice had been considered by the Mission Management Team before deciding to proceed and that a further periodic monitoring of that condition was planned. I further stated that I had been made aware of the recovery area weather previously and planned to place a call to Mr. Aldrich and advise him that the weather in the recovery area exceeded the Launch Commit Criteria.

So I stated earlier, when you asked what were the Launch Commit Criteria, one of them was that the recovery area weather has limitations on it. The report we had, that Mr. McDonald confirmed, was that we were outside of those limits.

Now, I must point out that that is not a hard Launch Commit Criteria. That is an advisory call, and the LCC so states that. It does require that we discuss the condition.

So at about 11:30 p.m., Mr. Cecil Houston established a teleconference with Mr. Aldrich and Mr. Sestile at KSC. I informed Mr. Aldrich that the weather in the [98] recovery area could preclude immediate recovery of the SRBs, since the ships were in a survival mode and they were moving back toward Cape Kennedy at about three knots, and the estimate provided to us by Mr. Sestile was that they would be probably 40 miles from the SRB impact area at the time of launch, at 9:38; and then, continuing at three knots, it was going to be some period of time before they could get back and locate the boosters.

The concern I had for that was not loss of the total booster, but loss of the main parachutes for the booster, which are separated at water impact, and loss of the frustum of the boosters, which has the drogue parachute on it, which comes down separately, because with the 50 knot winds we had out there and with the kind of sea states we had, by the time the recovery ships got back out there, there was little probability of being able to recover those.

I informed Mr. Aldrich of that, and he decided to proceed with the launch after that information. I did not discuss with Mr. Aldrich the conversations that we had just completed with Morton Thiokol.

Chairman Rogers: Could you explain why? Mr. Mulloy: Yes, sir. At that time, and I still consider today, that was a Level III issue, Level III being an SRB element or an external tank element or Space Shuttle main engine element or an Orbiter. There was no violation of Launch Commit Criteria. There was no waiver required in my judgment at that time and still today.

And we work many problems at the Orbiter and the SRB and the External Tank level that never get communicated to Mr. Aldrich or Mr. Moore. It was clearly a Level III issue that had been resolved.

. . . There were 27 full-scale seal tests with an O-ring groove damage tolerances, damage in the grooves and damage tolerance on O-rings. And then there were two cold gas tests.

And these data were presented on the night of the 27th. All of that was at ambient temperature. And then we did discuss what is a development qualification motor experience range, and that is shown on the chart. We had experience everywhere from 40 to 85 degrees.

There then were data presented on two cold gas tests at 30 degrees, where the O-ring was pressurized at the motor pressurization rate at 30 degrees, which would indicate that an O-ring would operate before joint rotation at 30 degrees.

Dr. Ride: Was that actually in a joint?

Mr. Mulloy: No, it is not. It is a full-scale O-ring, full-scale groove, in a scaled test device, where the pressurize rate on that O-ring is zero to 900 psi [pounds per square inch] in 600 milliseconds at a temperature of 30 degrees.

Dr. Walker: You would say, then, the O-ring was qualified to a temperature of 30 degrees? Would that be an accurate statement?

Mr. Mulloy: The day that we were looking at it, on the 27th, these two tests that we did indicated that it would perform at 30 degrees under the motor pressurization rate before the joint rotated.

Dr. Walker: What about, let's consider the putty and the O-ring, because that is really the system that responds to the pressure surge. What temperature was the putty/O-ring system qualified to?

Mr. Mulloy: The lowest that I'm aware of-and we're still flushing this out, because this is kind of what we talked about on the 27th, but the lowest that I'm aware of is the 40-degree test on one of the development motors.

Dr. Walker: And, of course, during those tests the putty was modified before the test. The putty was not just laid up and then the seal made. The putty was then smoothed out or some attempt was made to remove the volcanoes, I think.

Mr. Mulloy: Because the horizontal assembly caused that.

Now, there's one other significant point on this chart that we did discuss, that we didn't have the quantities on on the 27th, and I mentioned this earlier. We have 150 case segment proof tests, with a large number of joints with a simulation of a cold O-ring. That is the 90 durometer with a .275, and that was at about 35 degrees.

[99] So those are the certification data that we kind of discussed, all of which we didn't discuss. The two cold gas tests we did, the segment proof tests we did, the development and qualification motor test we did, as a basis for understanding what we could expect to happen at colder temperatures on the joints.


Mr. Hardy testified as follows:20


Mr. Hardy: At the teleconference on the evening of January 27, 1986, Thiokol engineering personnel in Utah reviewed charts that had been datafaxed to Huntsville and KSC participants just prior to the beginning of the conference. Now, I am not going to repeat a lot of what you have already heard, but I will give you some of my views on the whole matter.

The presentations were professional in nature. There were numerous questions and answers. There was a discussion of various data and points raised by individuals at Thiokol or at Marshall or at Kennedy. I think it was a rather full discussion. There were some 14 charts presented, and as has been mentioned earlier, we spent about two, two and a half hours reviewing this. To my knowledge, anyone who desired to make a point, ask a question or express a view was in no way restrained from doing so.

As others have mentioned, I have heard this particular teleconference characterized as a heated discussion. I acknowledge that there were penetrating questions that were asked, I think, from both, from all people involved. There were various points of view and an interpretation of the data that was exchanged. The discussion was not, in my view, uncharacteristic of discussions on many flight readiness issues on many previous occasions. Thiokol engineering concluded their presentation with recommendation that the launch time be determined consistent with flight experience to date, and that is the launch with the O-ring temperatures at or greater than 53 degrees Fahrenheit.

Mr. Kilminster at Thiokol stated . . . to the best of my recollection, that with that engineering assessment, he recommended we not launch on Tuesday morning as scheduled. After some short discussion, Mr.

Mulloy at KSC summarized his assessment of the data and his rationale with that data, and I think he has testified to that.

Mr. Reinartz, who was at KSC, asked me for comment, and I stated I was somewhat appalled, and that was referring specifically to some of the data or the interpretation of some of the data that Thiokol had presented with respect to its influence on the joint seal performance relative to the issue under discussion, which specifically was the possibility that the primary seal may take longer to actuate and therefore to blow by the primary seal. The blow-by of the primary seal may be longer, and I am going to elaborate on that a little further in this statement.

Then I went on to say that I supported the assessment of data presented essentially as summarized by Mr. Mulloy, but I would not recommend launch over Thiokol's objections.

Somewhere about this time, Mr. Kilminster at Utah stated that he wanted to go off the loop to caucus for about five minutes. I believe at this point Mr. McDonald, the senior Thiokol representative at KSC for this launch suggested to Mr. Kilminster that he consider a point that I think I had made earlier, that the secondary O-ring is in the proper position to seal if blow-by of the primary O-ring occurred.

I clearly interpreted this as a somewhat positive statement of supporting rationale for launch.... The status of the caucus by Thiokol lasted some 30, 35 minutes. At Huntsville during this Thiokol caucus, we continued to discuss the data presented. We were off the loop, we were on mute. We were around a table in small groups. It was not an organized type discussion. But I did take that opportunity to discuss my assessment and understanding of the data with several of my key advisors, and none of us had any disagreement or differences in our interpretation of what we believed the data was telling us with regard to the primary issue at hand.

When Thiokol came back on line, Mr. Kilminster reviewed rationale that supported proceeding with the launch and so recommended.

[100] Mr. Reinartz asked if anyone in the loop had a different position or disagreed or something to that effect, with the Thiokol recommendation as presented by Mr. Kilminster. There were no dissenting responses.

The telecon was terminated shortly after, and I have no knowledge of any subsequent events or discussions between personnel at KSC or at Thiokol on this matter.


At about 5:00 a. m . on January 28, a discussion took place among Messrs. Mulloy, Lucas, and Reinartz in which Mulloy reported to Lucas only that there had been a discussion with Thiokol over their concerns about temperature effects on the O-rings, and that it had been resolved in favor of launch. The following testimony of Mr. Mulloy and Dr. Lucas recount that discussion: 21


General Kutyna: . . . Larry, let me follow through on that, and I am kind of aware of the launch decision process, and you said you made the decision at your level on this thing.

If this were an airplane, an airliner, and I just had a two-hour argument with Boeing on whether the wing was going to fall off or not, I think I would tell the pilot, at least mention it.

Why didn't we escalate a decision of this importance ?

Mr. Mulloy: I did, sir.

General Kutyna: You did? Mr. Mulloy: Yes, sir.

General Kutyna: Tell me what levels above you.

Mr. Mulloy: As I stated earlier, Mr. Reinartz, who is my manager, was at the meeting, and on the morning, about 5:00 o'clock in the operations support room where we all were I informed Dr. Lucas of the content of the discussion.

General Kutyna: But this is not in the launch decision chain.

Mr. Mulloy: No, sir. Mr. Reinartz is in the launch decision chain, though.

General Kutyna: And is he the highest level in that chain?

Mr. Mulloy: No. Normally it would go from me to Mr. Reinartz to Mr. Aldrich to Mr. Moore.


Dr. Lucas' testimony is as follows:22


Chairman Rogers: Would you please tell the Commission when you first heard about the problem of the O-rings and the seals insofar as it involves launch 51-L? And I don't want you to go way back, but go back to when you first heard. I guess it was on January 27th, was it?

Dr. Lucas: Yes, sir. It was on the early evening of the 27th, I think about 7:00 p.m., when I was in my motel room along with Mr. Kingsbury. And about that time, Mr. Reinartz and Mr. Mulloy came to my room and told me that they had heard that some members of Thiokol had raised a concern about the performance of the Solid Rocket Boosters in the low temperature that was anticipated for the next day, specifically on the seals, and that they were going out to the Kennedy Space Center to engage in a telecon with the appropriate engineers back at Marshall Space Flight Center in Huntsville and with corresponding people back at the Wasatch division of Thiokol in Utah.

And we discussed it a few moments and I said, fine, keep me informed, let me know what happens.

Chairman Rogers: And when was the next time you heard something about that?

Dr. Lucas: The next time was about 5:00 a.m. on the following morning, when I went to the Kennedy Space Center and went to the launch control center. I immediately saw Mr. Reinartz and Mr. Mulloy and asked them how the matter of the previous evening was dispositioned.

Chairman Rogers: You had heard nothing at all in between?

Dr. Lucas: No, sir.

Chairman Rogers: So from 8:00 o'clock that evening until 5:00 o'clock in the morning, you had not heard a thing?

Dr. Lucas: It was about 7:00, I believe, sir. But for that period of time, I heard nothing in the interim. . .

Chairman Rogers: . . . And you heard Mr. Reinartz say he didn't think he had to notify you, or did he notify you?

Dr. Lucas: He told me, as I testified, when I went into the control room, that an issue had been resolved, that there were some people [101] at Thiokol who had a concern about the weather, that that had been discussed very thoroughly by the Thiokol people and by the Marshall Space Flight Center people, and it had been concluded agreeably that there was no problem, that he had a recommendation by Thiokol to launch and our most knowledgeable people and engineering talent agreed with that. So from my perspective, I didn't have-I didn't see that as an issue.

Chairman Rogers: And if you had known that Thiokol engineers almost to a man opposed the flight, would that have changed your view?

Dr. Lucas: I'm certain that it would.

Chairman Rogers: So your testimony is the same as Mr. Hardy's. Had he known, he would not have recommended the flight be launched on that day.

Dr. Lucas: I didn't make a recommendation one way or the other. But had I known that, I would have then interposed an objection, yes.

Chairman Rogers: I gather you didn't tell Mr. Aldrich or Mr. Moore what Mr. Reinartz had told you?

Dr. Lucas: No, sir. That is not the reporting channel. Mr. Reinartz reports directly to Mr. Aldrich. In a sense, Mr. Reinartz informs me as the institutional manager of the progress that he is making in implementing his program, but that I have never on any occasion reported to Mr. Aldrich.

Chairman Rogers: And you had subsequent conversations with Mr. Moore and Mr. Aldrich prior to the flight and you never mentioned what Mr. Reinartz had told you? Dr. Lucas: I did not mention what Mr. Reinartz told me, because Mr. Reinartz had indicated to me there was not an issue, that we had a unanimous position between Thiokol and the Marshall Space Flight Center, and there was no issue in his judgment, nor in mine as he explained it to me. Chairman Rogers: But had you known, your attitude would have been totally different?

Dr. Lucas: Had I had the advantage at that time of the testimony that I have heard here this week, I would have had a different attitude, certainly.

Chairman Rogers: In view of the fact that you were running tests to improve the joint, didn't the fact that the weather was so bad and Reinartz had told you about the questions that had been raised by Thiokol, at least, didn't that cause you serious concern? Dr. Lucas: I would have been concerned if Thiokol had come in and said, we don't think you should launch because we've got bad weather.

Chairman Rogers: Well, that's what they did, of course, first. That is exactly what they did. You didn't know that?

Dr. Lucas: I knew only that Thiokol had raised a concern.

Chairman Rogers: Did you know they came and recommended against the launch, is the question?

Dr. Lucas: I knew that I was told on the morning of the launch that the initial position of some members of Thiokol-and I don't know who it was-had recommended that one not launch with the temperature less than 53 degrees Fahrenheit.

Chairman Rogers: And that didn't cause you enough concern so you passed that information on to either Mr. Moore or Mr. Aldrich?

Dr. Lucas: No, sir, because I was shown a document signed by Mr. Kilminster that indicated that that would not be significant, that the temperature would not be-that it would be that much lower, as I recall it.


It is clear that crucial information about the O-ring damage in prior flights and about the Thiokol engineers' argument with the NASA telecon participants never reached Jesse Moore or Arnold Aldrich, the Levels I and II program officials, or J.A. (Gene) Thomas, the Launch Director for 51-L. The testimony of Aldrich describes this failure of the communication system very aptly:23


Dr. Feynman: . . . have you collected your thoughts yet on what you think is the cause-I wouldn't call it of the accident but the lack of communication which we have seen and which everybody is worried about from one level to another? . . .

Mr. Aldrich: Well, there were two specific breakdowns at least, in my impression, [102] about that situation. One is the situation that occurred the night before the launch and leading up to the launch where there was a significant review that has been characterized in a number of ways before the Commission and the Commission's Subpanels and the fact that that was not passed forward.

And I can only conclude what has been reported, and that is that the people responsible for that work in the Solid Rocket Booster project at Marshall believed that the concern was not of a significance that would be required to be brought forward because clearly the program requirements specify that critical problems should be brought forward to Level II and not only to Level II but through myself to Level I.

The second breakdown in communications, however, and one that I personally am concerned about is the situation of the variety of reviews that were conducted last summer between the NASA Headquarters Organization and the Marshall Organization on the same technical area and the fact that that was not brought through my office in either direction-that is, it was not worked through-by the NASA Headquarters Organization nor when the Marshall Organization brought these concerns to be reported were we involved.

And I believe that is a critical breakdown in process and I think it is also against the documented reporting channels that the program is supposed to operate to.

Now, it in fact did occur in that matter. In fact, there is a third area of concern to me in the way the program has operated. There is yet one other way that could have come to me, given a different program structure. I'm sure you've had it reported to you as it has been reported to me that in August or I think or at least at some time late in the summer or early fall the Marshall SRB project went forward to procure some additional Solid Rocket Motor casings to be machined and new configurations for testing of the joints.

Now it turns out that the budget for that kind of work does not come through my Level II office. It is worked directly between the Marshall Center in NASA Headquarters and there again had I been responsible for....


Shuttle Program Management Structure.

Shuttle Program Management Structure.


[103] ....the budget for that sort of work, it would have to come through me, and it would have been clear that something was going on here that I ought to know about.

And so there are three areas of' breakdown, and I haven't exactly answered your question. But I have explained it in the way that I best know it and-well, I can say a fourth thing.

There was some discussion earlier about the amount of material that was or was not reported on O-ring erosion in the FRRs [Flight Readiness Reviews] and I researched the FRR back reports and also the flight anomaly reports that were forwarded to my center-to my office-by the SRB [Solid Rocket Booster] project and as was in-dicated, there is a treatment of the Solid Rocket Motor O-ring erosion, I believe, for the STS 41-C FRR, which quantifies it and indicates some limited amount of concern.

The next time that is mentioned, I believe it is the STS 51-E, FRR in January 1985 or early in February, and that indicates, again, a reference to it but refers back to the 41-C as the only technical data.

And then from there forward the comment on O-ring erosion only is that there was another instance and it is not of concern.

Clearly the amount of reporting in the FRR is of concern to me, but in parallel with that, each of the flight anomalies in the STS program are required to be logged and reviewed by each of the projects and then submitted through the Level II system for formal close-out.

And in looking back and reviewing the anomaly close-outs that were submitted to Level II from the SRB project, you find that O-ring erosion was not considered to be an anomaly and, therefore, it was not logged and, therefore, there are not anomaly reports that progress from one flight to the other.

Yet, that is another way that that information could have flagged the system, and the system is set up to use that technique for flagging.

But if the erosion is classified as not an anomaly, it then is in some other category and the system did not force it in that direction. None of those are very focused answers, but they were all factors.


The Commission Chairman, Mr. Rogers, asked four key officials about their knowledge of the Thiokol objections to launch: 24


Chairman Rogers: . . . By way of a question, could I ask, did any of your gentlemen prior to launch know about the objections of Thiokol to the launch?

Mr. Smith [Kennedy Space Center Director]: I did not.

Mr. Thomas [Launch Director]: No, sir. Mr. Aldrich [Shuttle Program Director]: I did not.

Mr. Moore [Associate Administrator for Space Flight]: I did not.


Additionally, in further testimony J.A. (Gene) Thomas commented on the launch.25


Mr. Hotz: . . . Mr. Thomas, you are familiar with the testimony that this Commission has taken in the last several days on the relationship of temperature to the seals in the Solid Rocket Booster?

Mr. Thomas: Yes, sir, I have been here all week.

Mr. Hotz: Is this the type of information that you feel that you should have as Launch Director to make a launch decision?

Mr. Thomas: If you refer to the fact that the temperature according to the Launch Commit Criteria should have been 53 degrees, as has been testified, rather than 31, yes, I expect that to be in the LCC. That is a controlling document that we use in most cases to make a decision for launch.

Mr. Hotz: But you are not really very happy about not having had this information before the launch?

Mr. Thomas: No, sir. I can assure you that if we had had that information, we wouldn't have launched if it hadn't been 53 degrees.


[104] Findings


l. The Commission concluded that there was a serious flaw in the decision making process leading up to the launch of flight 51-L. A well structured and managed system emphasizing safety would have flagged the rising doubts about the Solid Rocket Booster joint seal. Had these matters been clearly stated and emphasized in the flight readiness process in terms reflecting the views of most of the Thiokol engineers and at least some of the Marshall engineers, it seems likely that the launch of 51-L might not have occurred when it did.

2. The waiving of launch constraints appears to have been at the expense of flight safety. There was no system which made it imperative that launch constraints and waivers of launch constraints be considered by all levels of management.

3. The Commission is troubled by what appears to be a propensity of management at Marshall to contain potentially serious problems and to attempt to resolve them internally rather than communicate them forward. This tendency is altogether at odds with the need for Marshall to function as part of a system working toward successful flight missions, interfacing and communicating with the other parts of the system that work to the same end.

4. The Commission concluded that the Thiokol Management reversed its position and recommended the launch of 51-L, at the urging of Marshall and contrary to the views of its engineers in order to accommodate a major customer.


Chronology of Events Related to Temperature Concerns Prior to Launch of Challenger (STS 51-L)



Key Participants



12:36 PM (EST)
January 27, 1986

NASA Project Managers and Contractor Support Personnel (including Morton Thiokol).

  • Launch Scrub. Decision is made to scrub due to high crosswinds at launch site.


l :00 PM ( EST)

Same as above.


  • Post-Scrub Discussion. All appropriate personnel are polled as to feasibility to launch again with 24-hour cycle and it results in no SRB constraints for launch at 9:38 AM, 28 January 1986.
  • Request is made for all participants to report any constraints.


1:00 PM (EST)

Kennedy Space Center

(1) Boyd C. Brinton, Manager, Space Booster Project, MTI;
(2) Lawrence O. Wear, Manager, SRM Project Office, Marshall.
  • Conversation. Wear asks Brinton if Thiokol had any concerns about predicted low temperatures and about what Thiokol had said about cold temperature effects following January 1985 flight 51-C.

Morton Thiokol, Utah

(1) Arnold R. Thompson, Supervisor, Rocket Motor Cases;
(2) Robert Ebeling, Manager, Ignition System and Final Assembly SRM Project.
  • Brinton telephones Thompson and other MTI personnel to ask them to determine if there were concerns based on predicted weather conditions. Ebeling and other engineers are notified and asked for evaluation.


[105] Approximately
2:00 PM (EST)

NASA Levels I and II Management With Appropriate Program Managers and Contract Personnel

(1) Jesse W. Moore, Associate Administrator, Space Flight, NASA HQ and Director, JSC;
(2) Arnold D. Aldrich, Manager, Space Transportation Systems Program, JSC;
(3) Lawrence B. Mulloy, Manager, SRB Project, Marshall Space Flight Center (MSFC)
(4) Dr. William Lucas, Director, MSFC.
  • Mission Management Team Meeting. Discussion is centered around the temperature at the launch facility and weather conditions predicted for launch at 9:38 AM on 28 January 1986.


2:30 PM (EST)

At Thiokol, Utah

(1) R. Boisjoly, Seal Task Force, Morton Thiokol, Utah;
(2) Robert Ebeling, Manager, Ignition System and Final Assembly, SRM Project.
  • Boisjoly learns of cold temperatures at Cape at meeting convened by Ebeling


4:00 PM (EST)

At Kennedy Space Center

(1) Allan J. McDonald, Director, SRM Project, Morton Thiokol;
(2) Carver Kennedy, Director of' Vehicle Assembly Building Operations, and Vice President of Space Operations at KSC, for Morton Thiokol. At Thiokol, Utah Robert Ebeling, Department Manager, Ignition System and Final Assembly, SRM Project.


  • Telephone Conversation. McDonald receives call at Carver Kennedy's residence from Ebeling expressing concern about performance of SRB field joints at low temperatures.
  • McDonald indicates he will call back latest temperature predictions up to launch time.
  • Carver Kennedy calls Launch Operations Center and received latest temperature information.
  • McDonald transmits data to Utah and indicates will set up telecon and asks engineering to prepare.


5:15 PM (EST)

At Kennedy Space Center

(1) Allan J. McDonald, Director, SRM Project, Morton Thiokol, Inc.;
(2) Cecil Houston, MSFC Resident Manager, at KSC.
  • Telephone Conversation. McDonald calls Cecil Houston informing him that Morton Thiokol engineering had concerns regarding O-ring temperatures.
  • Cecil Houston indicates he will set up teleconference with Marshall Space Flight Center and Morton Thiokol.


[106] Approximately
5:25 PM (EST)

At Kennedy Space Center

Cecil Houston, MSFC Resident Manager, at KSC.

At Marshall Space Flight Center

Judson A. Lovingood, Deputy Manager, Shuttle Projects Office, MSFC.


  • Telephone Conversation. Cecil Houston calls Lovingood, informing him of the concerns of temperature on the O-rings and asks him to establish a telecon with:
    (1) Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC (at Kennedy);
    (2) Lawrence B. Mulloy, Manager, SRB Project, MSFC (at Kennedy);
    (3) George Hardy, Deputy Director, Science and Engineering (at Marshall);
    (4) Thiokol Wasatch Division personnel.


5:30 PM (EST)


At Kennedy Space Center

Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC

At Marshall Space Flight Center

Judson A. Lovingood, Deputy Manager, Shuttle Projects Office, MSFC.

  • Telephone Conversation. Lovingood calls Reinartz to inform him of planned 5:45 PM (EST) teleconference.
  • Lovingood proposes that Kingsbury (Director of Science and Engineering MSFC), participate in teleconference.


5:45 PM (EST)


At Kennedy Space Center

Stanley R. Reinartz, Manager, Shuttle Projects Office (MSFC).

At Marshall Space Flight Center

Judson A. Lovingood, Deputy Manager, Shuttle Projects Office, MSFC.

Plus other personnel at Kennedy, Marshall, and Thiokol, Utah.

  • First Teleconference. Concerns regarding temperature effects on the O-rings are discussed.
  • MTI is of the opinion launch should be delayed until Noon or afternoon.
  • It is decided that another telecon at 8:15 PM will be set up to transmit the data to all of the parties and to have more personnel involved.
  • Lovingood recommends to Reinartz to include Lucas, Director, MSFC and Kingsbury in 8:45 PM conference and to plan to go to Level II if MTI recommends not launching.


6:30 PM (EST)

At Marshall Space Flight Center

Judson A. Lovingood, Deputy Manager, Shuttle Projects Office MSFC.

At Kennedy Space Center

Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC.

  • Telephone Conversation. Lovingood calls Reinartz and tells him that if Thiokol persists, they should not launch.
  • Lovingood also suggests advising Aldrich, Manager, National Transportation System (Level II), of teleconference to prepare him for Level I meeting to inform of possible recommendation to delay.


[107] Approximately
7:00 PM (EST)


At Kennedy Space Center

(1) Lawrence B. Mulloy, Manager, SRB Project, MSFC.
(2) Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC;
(3) Dr. William Lucas, Director, MSFC;
(4) Jim Kingsbury, Director of Science and Engineering, MSFC.
  • Conversation. Reinartz and Mulloy visit Lucas and Kingsbury in their motel rooms to inform them of Thiokol concern and planned teleconference.


8:45 PM (EST)

At Morton Thiokol, Utah

(1) Jerald Mason, Senior Vice President, Wasatch Operations;
(2) Calvin Wiggins, Vice President and General Manager, Space Division, Wasatch;
(3) Joe C. Kilminster, Vice President, Space Booster Programs, Wasatch;
(4) Robert K. Lund, Vice President, Engineering;
(5) Roger Boisjoly, Member Seal Task Force;
(6) Arnold R. Thompson, Supervisor, Rocket Motor Cases.

At Kennedy Space Center

(1) Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC;
(2) Lawrence B. Mulloy, Manager, SRB Project, MSFC;
(3) Allan J. McDonald, Director, SRM Project, MTI.

At Marshall Space Flight Center

(1) George B. Hardy, Deputy Director, Science and Engineering;
(2) Judson A. Lovingood, Deputy Manager, Shuttle Project Office;
(3) Ben Powers, Engineering Structures and Propulsion. Plus other personnel (see table page 111).


  • Second Teleconference. Charts present a history of the O-ring erosion and blow-by for the primary seal in the field joints, including results of subscale tests, previous flights and static tests of Solid Rocket Motors.
  • The data shows that the timing function of the O-rings will be slower due to lower temperatures and that the worst blow-by occurred on SRM 15 (STS 51-C) in January 1985 with O-ring temperatures of 53 degrees Fahrenheit.
  • Recommendation by Thiokol (Lund) is not to fly STS 51-L (SAM-25) until the temperature of the O-ring reached 53 degrees Fahrenheit, which was the lowest temperature of any previous flight.
  • Mulloy asks for recommendation from Kilminster.
  • Kilminster states that based upon the engineering recommendation, he can not recommend launch.
  • Hardy is reported by both McDonald and Boisjoly to have said he is "appalled" by Thiokol's recommendation.
  • Reinartz comments that he is under the impression that SRM is qualified from 40 degrees Fahrenheit to 90 degrees Fahrenheit. ~ NASA personnel challenge conclusions and recommendations.
  • Kilminster asks for five minutes off

[108] Time

Key Participants



10:30 PM (EST)

Thiokol Personnel

(1) Jerald Mason, Senior Vice President, Wasatch Operations;
(2) Joe C. Kilminster, Vice President, Space Booster Program;
(3) Calvin Wiggins, Vice President and General Manager, Space Division;
(4) Robert K. Lund, Vice President, Engineering;
(5) Arnold R. Thompson, Supervisor, Rocket Motor Cases;
(6) Roger Boisjoly, Member, Seal Task Force;
(7) Brian Russell, Special Projects SRM Program Office;
(8) Robert Ebeling, Manager, Ignition System and Final Assembly, SRM Project.
Plus other personnel


  • Thiokol Caucus. Caucus continues for about 30 minutes at Thiokol, Wasatch, Utah.
  • Major issues are (1) temperature effects on O-ring, and (2) erosion of the O-ring.
  • Thompson and Boisjoly voice objections to launch and indication is that Lund also is reluctant to launch.
  • A final management review is conducted with only Mason, Lund, Kilminster, and Wiggins.
  • Lund is asked to put on management hat by Mason.
  • Final agreement is: (1) there is a substantial margin to erode the primary O-ring by a factor of three times the previous worst case, and (2) even if the primary O-ring does not seal, the secondary is in position and will.



10:30 PM to 11:00 PM (EST)


At Kennedy Space Center

(1) Allan J. McDonald, Manager, Space Booster Project, Morton Thiokol, Inc. (MTI);
(2) Lawrence B. Mulloy, Manager, SRB Projects, MSFC;
(3) Stanley R. Reinartz, Manager, Shuttle Projects, MSFC;
(4) Jack Buchanan, Manager, KSC Operations, for MTI;
(5) Cecil Houston, MSFC Resident manager, at KSC.


  • Conversation at Kennedy. McDonald continues to argue for delay.
  • McDonald challenges Reinartz's rationale that SRM is qualified at 40 degrees F. to 90 degrees F., and Mulloy's explanation that Propellant Mean Bulk Temperatures are within specifications.



11:00 PM (EST)


Same participants at 8:45 PM Teleconference.


  • Second Teleconference (Cont'd). Thiokol indicates it had reassessed; temperature effects are concern, but data is inconclusive.
  • Kilminster reads the rationale for recommending launch.
  • Thiokol recommends launch.
  • Hardy requests that Thiokol put: writing their recommendation and send it by fax to both Kennedy and Marshall.



[109] Approximately
11:15 to 11:30 PM (EST)

At Kennedy Space Center

(1) Allan J . McDonald, Manager, Space Booster Project, MTI;
(2) Lawrence Mulloy, Manager, SRB Projects Office, MSFC;
(3) Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC;
(4) Jack Buchanan, Manager, KSC Operations, for MTI;
(5) Cecil Houston, Manager, MSFC Resident Office at KSC.


  • Conversation at Kennedy. McDonald argues again for delay asking how NASA could rationalize launching below qualification temperature.
  • McDonald indicates if anything happened, he would not want to have to explain to Board of Inquiry.
  • McDonald indicates he would cancel launch since (1) O-ring problem at low temperatures; (2) booster recovery ships heading into wind toward shore due to high seas, and (3) icing conditions on launch pad.
  • McDonald is told it is not his concern and that his above concerns will be passed on in advisory capacity.


11:45 PM (EST)

  • Telefax. Kilminster faxes Thiokol's recommendation to launch at 9:45 M EST, 27 January 1986 ( 11 :45 EST
  • Fax is signed by Kilminster.
  • McDonald retrieves fax at KSC.


11:30 PM to 12:00 AM (EST)

At Kennedy Space Center

(1) Lawrence B. Mulloy, Manager, SRB Projects Office, MSFC;
(2) Stanley R. Reinartz, Manager, Shuttle Projects, MSFC;
(3) Arnold D. Aldrich, Manager, National Space Transportation System Program Office, JSC.


  • Teleconference. Discussion centers around the recovery ships' activities and brief discussion of the ice issue on the launch complex area.
  • Reinartz and Mulloy place call to Aldrich.
  • McDonald delivers fax to Jack Buchanan's office at Kennedy Space Center and overhears part of conversation.
  • Aldrich is apparently not informed of the O-ring concerns.


12:01 AM (EST)
January 28

  • Kennedy Space Center meeting breaks up.



1:30 to 3:00 AM (EST)

At Kennedy Space Center

(1) Charles Stevenson, Supervisor of Ice Crew; KSC
(2) B.K. Davis, Ice Team Member, MSFC
  • Ice Crew Inspection of Launch Pad B.
  • Ice crew finds large quantity of ice on Fixed Service Structure, mobile launch platform, and pad apron; and reports conditions.


5:00 AM (EST)

At Kennedy Space Center

(1) Lawrence B. Mulloy, Manager, SRB Project, MSFC;
(2) Dr. William Lucas, Director, (MSFC);
(3) Jim Kingsbury, Director of Science and Engineering, MSFC.
  • Conversation. Mulloy tells Lucas of Thiokol's concerns over temperature effects on O-rings and final resolution.
  • Lucas is shown copy of Thiokol telefax.


[110] Approximately
7:00-9:00 AM (EST)

At Kennedy Space Center

(1) Charles Stevenson, Supervisor of Ice Crew, KSC;
(2) B. K. Davis, Ice Team Member MSFC .
  • Ice Crew Inspection of Launch Pad B. Ice crew inspects Launch Pad B and Challenger for ice formation.
  • Davis measures temperatures on SRBs, External Tank, Orbiter, and launch pad with infrared pyrometer.
  • Left-hand SRB appears to be about 25 degrees F. and right-hand SRB appears to be about 8 degrees F. near the aft region.
  • Ice crew is not concerned since there is no Launch Commit Criteria on surface temperatures and does not report.
  • Crew reports patches of sheet ice on lower segment and skirt of left Solid Rocket Booster.


8:00 AM (EST)

At Marshall Space Flight Center

(1) Judson A. Lovingood, Deputy Manager, Shuttle Projects Office, MSFC;
(2) Jack Lee, Deputy Director MSFC.
  • Conversation. Lovingood informs Lee of previous night's discussions.
  • He indicates that Thiokol had at first recommended not launching, and then after Wasatch conference recommended launching.
  • He also informs Lee that Thiokol is providing in writing their recommendation for launch.


9:00 AM (EST)

NASA Levels I and Level II Management With Appropriate Project Managers and Contract Personnel.

  • Mission Management Team Meeting. Ice conditions at launch complex are discussed. There is no apparent discussion of temperature effects on O-ring seal.


10:30 AM (EST)

At Kennedy Space Center

(1) Charles Stevenson, Supervisor of Ice Crew;
(2) B.K. Davis, Ice Team Member
  • Ice Crew Inspection of Launch Pad B. Ice crew inspects Launch Pad B for third time.
  • Crew removes ice from water troughs, returns to Launch Control Center at T-20 minutes, reports conditions to Mission Management Team including fact that ice is still on left Solid Rocket Booster.


11:38 AM (EST)

  • Launch. Challenger (STS 51-L) is launched.


[111] Final Teleconference Participants

NASA Marshall Space Flight Center



Morton Thiokol Wasatch Division



1. George B. Hardy, Deputy Director, Science and Engineering, MSFC

1. Jerald Mason, Senior Vice President, Wasatch Operations, MTI

2. Judson A. Lovingood, Deputy Manager, Shuttle Projects Office, MSFC

2. Calvin Wiggins, Vice President and General Manager, Space Division, MTI

3. Leslie F. Adams, Deputy Manager, SRB Project, MSFC

3. Joe C. Kilminster, Vice President, Space Booster Programs, MTI

4. Lawrence O. Wear, Manager, SRM Project Office, MSFC

4. Robert K. Lund, Vice President, Engineering, MTI

5. John Q. Miller, Technical Assistant, SRM Project, MSFC

5. Larry H. Sayer, Director, Engineering and Design, MTI

6. J. Wayne Littles, Associate Director for Engineering, MSFC

6. William Macbeth, Manager, Case Projects, Space Booster Project Engineering, Wasatch Division, MTI

7. Robert J. Schwinghamer, Director, Material and Processes Laboratory, MSFC

7. Donald M. Ketner, Supervisor, Gas Dynamics Section and Head Seal Task Force, MTI

8. Wilbur A. Riehl, Chief, Nonmetallic Materials Division, MSFC

8. Roger Boisjoly, Member, Seal Task Force, MTI

9. John P. McCarty, Deputy Director, Structures and Propulsion Laboratory, MSFC

9. Arnold R. Thompson, Supervisor, Rocket Motor Cases, MTI

10. Ben Powers, Engineering Structures and Propulsion Laboratory, MSFC

10. Jack R. Kapp, Manager, Applied Mechanics Department, MTI

11. James Smith, Chief Engineer, SRB Program, MSFC

11. Jerry Burn, Associate Engineer, Applied Mechanics, MTI

12. Keith E. Coates, Chief Engineer, Special Projects Office, MSFC

12. Joel Maw, Associate Scientist, Heat Transfer Section, MTI

13. John Schell, Retired Engineer, Materials Laboratory, MSFC

13. Brian Russell, Manager, Special Projects, SRM Project, MTI

Present at KSC

14. Robert Ebeling, Manager, Ignition System and Final Assembly, SRB Project, MTI

14. Cecil Houston, MSFC Resident Manager, at KSC

Present at MSFC

15. Stanley R. Reinartz, Manager, Shuttle Projects Office, MSFC

15. Boyd C. Brinton, Manager, Space Booster Project, MTI

16. Lawrence B. Mulloy, Manager, SRB Project, MSFC

16. Kyle Speas, Ballistics Engineer, MTI

Present at KSC

17. Allan J. McDonald, Director, SRM Project, MTI

18. Jack Buchanan, Manager, KSC Operations, MTI



Above, Shuttle 51-L on Kennedy Space Center Pad 39B in the early morning of launch day. Temperatures were well below freezing, as indicated by the lower left photo, which shows thick ice in a water trough despite the use of an anti-freeze solution.

Above, Shuttle 51-L on Kennedy Space Center Pad 39B in the early morning of launch day. Temperatures were well below freezing, as indicated by the lower left photo, which shows thick ice in a water trough despite the use of an anti-freeze solution.


Above [upper left], foot long icicles on a lower level of the Fixed Service Structure frame the attachment point where the Orbiter is attached to the external tank (arrow). Icing was even more extensive at upper levels of the service structure [(upper right, lower left)]. At right below is a ground communications box (not used during launch) rendered inoperable by heavy ice.

Above [upper left], foot long icicles on a lower level of the Fixed Service Structure frame the attachment point where the Orbiter is attached to the external tank (arrow). Icing was even more extensive at upper levels of the service structure [(upper right, lower left)]. At right below is a ground communications box (not used during launch) rendered inoperable by heavy ice.


[114] Ambiguities In The Decision Making Process

During the night and early morning of January 28, another problem was developing due to the extreme cold weather, predicted to be in the low 20s for approximately 11 hours. Reaction control system heaters on the Orbiter were activated and the Solid Rocket Booster recovery batteries were checked and found to be functioning within specifications. There were no serious concerns regarding the External Tank. The freeze protection plan for the launch pad was implemented, but the results were not what had been anticipated. The freeze protection plan usually involves completely draining the water system. However, this was not possible because of the imminent launch of 51-L. In order to prevent pipes from freezing, a decision was made to allow water to run slowly from the system. This had never been done before, and the combination of freezing temperatures and stiff winds caused large amounts of ice to form below the 240-foot level of the fixed service structure including the access to the crew emergency egress slide wire baskets. Ice also was forming in the water trays beneath the vehicle.

These conditions were first identified by the Ice Team at approximately 2:00 a.m. on January 28 and were assessed by management and engineering throughout the night, culminating with a Mission Management Team meeting at 9:00 a.m. At this meeting, representatives for the Orbiter prime contractor, Rockwell International, expressed their concern about what effects the ice might have on the Orbiter during launch. Rockwell had been alerted about the icing conditions during the early morning and was working on the problem at its Downey, California, facility.

During Commission hearings, the president of Rockwell's Space Transportation Systems Division, Dr. Rocco Petrone, and two of his vice presidents, Robert Glaysher and Martin Cioffoletti, all described the work done regarding the ice conditions and the Rockwell position at the 9:00 a.m. meeting with regard to launch. Dr. Petrone had arrived at Kennedy on Friday, January 24. On Monday the 27th he left to return to Rockwell's facility in California, but Glaysher and Cioffoletti remained at Kennedy. Dr. Petrone testified that he first heard about the ice at 4:00 a.m. Pacific Standard Time. He explained what followed: 26

"I had gotten up and went to the support room to support this launch. We have people monitoring consoles, and I checked in, and they told me there was a concern, and when I arrived at about 4:30, 4:40 (PST), I was informed we were working the problem with our aerodynamicist and debris people, but very importantly, we would have to make an input to Kennedy for a meeting scheduled at 6:00 o'clock our time and 9:00 o'clock Florida time.

"We had approximately an hour of work to bring together. The work had been underway when I arrived and was continuing.

"At that time I got on the phone with my Orbiter program managers just to discuss background of where we were, how things stood, and what their concerns were locally. They described what they knew in Florida, and we also in Downey did television input, and we could see some of the ice scenes that were shown here this morning.

"We arrived through a series of meetings to a top level discussion at approximately 5:30 Pacific Standard Time, from which we drew the following conclusions: Ice on the mobile launcher itself, it could be debris. We were very concerned with debris of any kind at the time of launch. With this particular ice, one, could it hit the Orbiter? There was wind blowing from the west. That appeared not to be so, that it wouldn't hit the Orbiter but would land on the mobile launcher. The second concern was what happens to that ice at the time you light your liquid fuel engines, the SSMEs, and would it throw it around and ricochet and potentially hit the Orbiter.

"The third aspect is the one that has been discussed here of aspiration, what would happen when the large SRM [Solid Rocket Motors] motors ignite and in effect suck in air, referred to as aspiration, and ice additionally would come down, how much unknown.

"The prime thing we were concerned about was the unknown base line. We had not launched in conditions of that nature, and we just felt we had an unknown.

"I then called my program managers over in Florida at 5:45 (PST) and said we could [115] not recommend launching from here, from what we see. We think the tiles would be endangered, and we had a very short conversation. We had a meeting to go through, and I said let's make sure that NASA understands that Rockwell feels it is not safe to launch, and that was the end of my conversation . "

Mr. Glaysher, who was at Kennedy, came to the center at approximately 7:45 a.m. EST. He conferred with Rockwell's Chief Engineer as well as the Vice President of Engineering, Dr. John Peller, at Rockwell's Downey plant. At 9:00 a.m., after the ice debris team had reported back from the pad inspection, Glaysher was asked for Rockwell's position on launch. He discussed aspiration effects, the possible ricochet of ice from the fixed service structure, and what the ice resting on the mobile launch platform would do at ignition. Glaysher said he told the Mission Management Team when it met at 9:00 a.m. that the ice was an unknown condition, and Rockwell was unable to predict where the ice would go or the degree of potential damage to the Orbiter thermal protection system if it were struck by the ice. He testified that his recommendation to NASA was: 27

"[M]y exact quote-and it comes in two parts. The first one was, Rockwell could not 100 percent assure that it is safe to fly which I quickly changed to Rockwell cannot assure that it is safe to fly .

Rockwell's other vice president at Kennedy, Martin Cioffoletti, described the concern about ice in a slightly different manner: 28


Mr. Cioffoletti: Similarly, I was called in and told about the problem and came into the 6:00 o'clock meeting which you heard about a few minutes ago, and at the conclusion of that meeting I spoke with Mr. Dick Kohrs, the deputy program manager from Johnson Space Flight Center, and he asked if we could get the Downey folks to look at the falling ice and how it might reverse toward the vehicle, and also, did we have any information on aspiration effects.

So I did call back to Downey and got the John Peller folks working on that problem, and they did, as you saw from Charlie Stevenson's sketches, predict that the ice would travel only about halfway to the vehicle, freefalling ice carried by the winds. So we felt that ice was not a problem. However, it would land on the mobile launch platform. That we considered a problem. We also investigated the aspiration data base we had, and we had seen the aspiration effect on previous launches where things were pulled into the SRB [Solid Rocket Booster] hole after ignition, but we had never seen anything out as far as the fixed surface tower. So we felt in fact it was an unknown. We did not have the data base to operate from an aspiration effect.

At the 9:00 o'clock meeting, I was asked by Arnie Aldrich, the program manager, to give him the results of our analysis, and I essentially told him what I just told you and felt that we did not have a sufficient data base to absolutely assure that nothing would strike the vehicle, and so we could not lend our 100 percent credence, if you will, to the fact that it was safe to fly .

I said I could not predict the trajectory that the ice on the mobile launch platform would take at SRB ignition.

Chairman Rogers: But I think NASA's position probably would be that they thought that you were satisfied with the launch. Did you convey to them in a way that they were able to understand that you were not approving the launch from your standpoint?

Mr. Cioffoletti: I felt that by telling them we did not have a sufficient data base and could not analyze the trajectory of the ice, I felt he understood that Rockwell was not giving a positive indication that we were for the launch.


After Cioffoletti's testimony at the Commission hearings, Dr. Petrone was pressed for a more detailed description of Rockwell's launch recommendation: 29


General Kutyna: Dr. Petrone, you've got a lot more experience than I have in this business, but the few launch conferences that I have been on the question is very simple. Are you go or are you no-go for launch, and `` maybe" isn't an answer. I hear all kinds of qualifications and cautions and considerations here.

Did someone ask you are you go or nogo? Was that not asked?

[116] Dr. Petrone: At this particular meeting, as far as-and I was not in Florida, and so I cannot answer that. It had been done at earlier meetings. This was a technical evaluation of a series of problems, and we talked about debris hitting the TPS [thermal protection system] and the tiles, and the long series of reviews that we had done that morning and all led us to a conclusion that they were not safe to fly.

And we transmitted that to program managers along with the technical evaluation quickly of why we had arrived at that.

So much of it is how the question gets raised because earlier we had aspiration work, ricochet work, a number of things which we did, and then we came up with our recommendation.

Chairman Rogers: And your recommendation now you say it was, it was unsafe to fly?

Dr. Petrone: Correct, sir.


Two things are apparent from the Rockwell testimony. First, Rockwell did not feel it had sufficient time to research and resolve the ice on the pad problem. Second, even though there was considerable discussion about ice, Rockwell's position on launch described above was not clearly communicated to NASA officials in the launch decision chain during the hours preceding 51-L's launch.

At a meeting with Commission investigators on March 4, 1986, at Kennedy, Horace Lamberth, NASA director of Shuttle Engineering, said he did not interpret Rockwell's position at the 9:00 a.m. Mission Management Team meeting on January 28 as being "no-go." Lamberth said the the language used by Rockwell was "we can't give you 100 percent assurance" but there was no feeling in his mind that Rockwell was voicing a no-go recommendation. "It just didn't come across as the normal Rockwell nogo safety of flight issues come across." 30 This conclusion is confirmed in part by an interview of Dr. John Peller, Rockwell's Vice President of Engineering, who was assigned the ice problem early Tuesday morning. Dr. Peller, in describing a telephone conversation with the Johnson Director of Engineering, Tom Moser, stated:31


Dr. Peller: That was a call from Tom Moser to me, in which he asked again to understand my concerns. And I just repeated the same concerns. And he asked, "Did I think that it was likely that the vehicle would take safety critical damage?"

And I said, "From the possibility that the vehicle would take safety critical damage," I said, "there's a probability in a sense that it was probably an unlikely event, but I could not prove that it wouldn't happen . . ."

. . . I never used the words "no-go" for launch. I did use the words that we cannot prove it is safe. And normally that's what we were asked to do. We were unable to do that in this particular case, although it was a strange case, that we normally don't get involved in.


Arnold Aldrich, NASA Mission Management Team Leader, described NASA's view of the ice situation and his recollection of Rockwell's position. He said that on Tuesday morning the mission management team did a detailed analysis of the ice on the fixed service structure. Representatives from the ice team, Rockwell, and the directors of Engineering (Horace Lamberth) and the Orbiter project (Richard Colonna) all considered the problem. Aldrich reported this discussion as follows : 32

"Following the discussion of the acceptability of the ice threat to the Orbiter, based upon the conditions described in detail of the fixed service structure-and some of that you've seen here portrayed well this morning-I asked the NASA managers involved for their position on what they felt about the threat of that to the Orbiter.

"Mr. Lamberth reported that KSC [Kennedy Space Center] engineering had calculated the trajectories, as you've heard, of the falling ice from the fixed service structure east side, with current 10-knot winds at 300 degrees, and predicted that none of this ice would contact the Orbiter during its ignition or launch sequence; and that their calculations even showed that if the winds would increase to 15 knots, we still would not have contact with the Orbiter.

"Mr. Colonna, Orbiter project manager, reported that similar calculations had been performed in Houston by the mission evaluation team there. They concurred in this assessment. And further, Mr. Colonna stated that, even if these calculations were [117] significantly in error, that it was their belief that falling ice from the fixed service structure, if it were in fact to make its way to the Orbiter, it would only be the most lightweight ice that was in that falling stream, and it would impact the Orbiter at a very oblique angle.

"Impacts of this type would have very low probability of causing any serious damage to the Orbiter, and at most would result in post-flight turnaround repairs.

"At this point I placed a phone call to Mr. Moser that I had previously mentioned, director of Engineering at the Johnson Space Center, who was in the mission evaluation room, and he confirmed the detailed agreement with Mr. Lamberth's and Mr. Colonna's position....

"And both Mr. Lamberth and Mr. Colonna reported that their assessment was that the time it took for the ice to fall, to hit the Orbiter and to rebound, and the location of the fixed service structure on the MLP [mobile launch platform] would not cause that ice in their view to be a concern to rebound and come up and impact the rear end of the Orbiter.

"Following these discussions, I asked for a position regarding proceeding with the launch. Mr. Colonna, Mr. Lamberth, and Mr. Moser all recommended that we proceed.

"At that time, I also polled Mr. Robert Glaysher, the vice president, Orbiter project manager, Rockwell International STS Division, and Mr. Marty Cioffoletti, Shuttle Integration Project Manager, Rockwell International STS Division. Mr. Glaysher stated-and he had been listening to this entire discussion and had not been directly involved with it, but had been party to this the whole time.

"His statement to me as best I can reconstruct it to report to you at this time was that, while he did not disagree with the analysis that JSC (Johnson Space Center) and KSC had reported, that they would not give an unqualified go for launch as ice on the launch complex was a condition which had not previously been experienced, and thus this posed a small additional, but unquantifiable, risk. Mr. Glaysher did not ask or insist that we not launch, however.

"At the conclusion of the above review, I felt reasonably confident that the launch should proceed."

In addition to Rockwell's input, Mr. Aldrich also had reports from other contractors and the ice, frost and debris team at the 9:00 session. Ice on the vehicle assembly appeared to be of no concern; sheet ice in the noise suppression trays had been broken up and removed; as previously noted the ice team reported that there was ice on the fixed service structure between 95 feet above ground and 215 feet; no ice above 255 feet. The north and west sides had large amounts of ice and icicles. The final assessment was made that the ice on the fixed service structure would not strike or damage the Orbiter tiles or the vehicle assembly during ignition or ascent, owing to the considerable horizontal distance between the service structure and the vehicle assembly. The decision was made to launch pending a final ice team review of the launch complex in order to assess any changes in the situation. This inspection was completed following the Mission Management Team meeting and the ice team report indicated no significant change.



The Commission is concerned about three aspects of the ice-on-the-pad issue.

1. An analysis of all of the testimony and interviews establishes that Rockwell's recommendation on launch was ambiguous. The Commission finds it difficult, as did Mr. Aldrich, to conclude that there was a no-launch recommendation. Moreover, all parties were asked specifically to contact Aldrich or Moore about launch objections due to weather. Rockwell made no phone calls or further objections to Aldrich or other NASA officials after the 9:00 Mission Management Team meeting and subsequent to the resumption of the countdown.

2. The Commission is also concerned about the NASA response to the Rockwell position at the 9:00 a.m. meeting. While it is understood that decisions have to be made in launching a Shuttle, the Commission is not convinced Levels I and II appropriately considered Rockwell's concern about the ice. However ambiguous Rockwell's position was, it is clear that they did tell NASA that the ice was an unknown condition. Given [118] the extent of the ice on the pad (see photos pages 112 and 113), the admitted unknown effect of the Solid Rocket Motor and Space Shuttle Main Engines ignition on the ice, as well as the fact that debris striking the Orbiter was a potential flight safety hazard, the Commission finds the decision to launch questionable under those circumstances. In this situation, NASA appeared to be requiring a contractor to prove that it was not safe to launch, rather than proving it was safe. Nevertheless, the Commission has determined that the ice was not a cause of the 51-L accident and does not conclude that NASA's decision to launch specifically overrode a no-launch recommendation by an element contractor.

3. The Commission concluded that the freeze protection plan for launch pad 39B was inadequate. The Commission believes that the severe cold and presence of so much ice on the fixed service structure made it inadvisable to launch on the morning of January 28, and that margins of safety were whittled down too far.

Additionally, access to the crew emergency slide wire baskets was hazardous due to ice conditions. Had the crew been required to evacuate the Orbiter on the launch pad, they would have been running on an icy surface. The Commission believes the crew should have been made aware of the situation, and based on the seriousness of the condition, greater consideration should have been given to delaying the launch.


[119] References

1. NASA Program Directive Shuttle FRR, September 26, 1983, Appendix K, Volume I.
2. Shuttle Projects Flight Readiness Review Mission 51-L, January 9. 1986.
3. STS 51-L Flight Readiness Review, Solid Rocket Booster, January 15, 1986.
4. STS 51-L Flight Readiness Review.
5. Commission Hearing Transcript, May 2, 1986, pages 2610-2611.
6. Commission Interview Transcript, Ebeling, R., March 19, 1986, page 13.
7. Commission Hearing Transcript, February 25, 1986, pages 1264-1268.
8. Commission Hearing Transcript, February 26, 1986, pages 1694-1697 and 1681.
9. Commission Hearing Transcript, February 25, 1986, pages 1412-1417.
10. Commission Hearing Transcript, February 25, 1986, pages 1268-1271.
11. Commission Hearing Transcript, February 14, 1986, pages 1078- 1080.
12. Commission Hearing Transcript, February 25, 1986, pages 1346-1347.
13. Commission Hearing Transcript, February 25, 1986, pages 1418-1422.
14. Commission Interview Transcript, April 1, pages 37-53.
15. Commission Hearing Transcript, February 25, 1986, pages 1456-1457.
16. Commission Interview Transcript, Mason, J., April 2, 1986, pages 24-26.
17. Commission Hearing Transcript, February 14, 1986, pages 1234-1236.
18. Commission Hearing Transcript, February 26, 1986, pages 1537-1541.
19. Commission Hearing Transcript, February 26, 1986, 1553-1566 and 1560-1563.
20. Commission Hearing Transcript, February 26, 1986, pages 1598-1601.
21. Commission Hearing Transcript, February 26, 1986, pages 1588- 1589.
22. Commission Hearing Transcript, February 27, 1986, pages 1867-1868 and 1876-1879.
23. Commission Hearing Transcript, April 3, 1986, pages 2538-2541.
24. Commission Hearing Transcript, February 27, 1986, page 1899.
25. Commission Hearing Transcript, February 27, 1986, pages 1932-1933.
26. Commission Hearing Transcript, February 27, 1986, pages 1798-1800.
27. Ibid, page 1802.
28. Ibid, pages 1803 - 1806.
29. Ibid, pages 1806 and 1807.
30. Commission Work Session, Pre-Launch, March 4, 1986, page 75.
31. Commission Interview Transcript, Peller, J., April 10, 1986, pages 13 - 14.
32. Commission Hearing Transcript, February 27, 1986, pages 1833-1836.

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