Transcript

COLUMBIA ACCIDENT INVESTIGATION BOARD
BRIEFING
HOUSTON, TEXAS
MARCH 11, 2003

Adm. Harold Gehman, USN, Chairman of CAIB
Maj. Gen. Kenneth Hess, Chief, Safety Center, Kirtland Air Force Base
Dr. Sheila Widnall, Vice President, National Academy of Engineering
Maj. Gen. John Barry, Director, Plans and Programs,
Headquarters Materiel Command, Wright-Patterson Air Force Base

GEHMAN: Good afternoon. I'm joined today by three of my colleagues on the board, one representing each of the sub boards or working groups that we have established. To my left is Ken Hess, who is working in the operations section. Beside him is John Barry, who's working in the section that's looking at materiel and maintenance issues. And to his left is Dr. Sheila Widnall, who's working on the engineering and technical evaluations section.

I'll make a few introductory comments and then each of them will make some short comments as to what their groups are working one and where their fellow board members are. And then we'll open it up to questions.

As is our practice every week, we try not to save up news for Tuesday. We do release things as they become apparent. The purpose of this press conference is really more of a dialogue so you can ask questions and get a two-way dialogue going with the board members on anything that you're interested in.

Once again, I think that we've had a good week here. We are moving along methodically in our understanding of what happened to the orbiter. That is--let me rephrase that. We're moving along nicely in our understanding of the forces that were at work on the orbiter as it failed to properly enter the Earth's atmosphere.

I would not want to say that we're moving along rapidly at finding the cause, because it remains to be elusive.

But we are doing a considerable amount of good hard engineering and science work at understanding the environment and the forces that the orbiter was subjected to and also narrowing down the part of the geography on the orbiter where the assault seems to have taken place.

Every time we do a little analysis, every time we see another study, it tends to focus us a little bit more. And I think that my colleagues here will talk about that some more.

We continue to rely primarily on the six major detective stories that I told you about before. And they are: the aerodynamic analysis; the thermal analysis; the videographic and picture analysis of debris shedding; the refinement of the time line; debris collection, lay out, analysis; and the material documentation of everything that was done to the orbiter or anyone who touched the orbiter in between its flights. And those are the six primary areas that we hope will lead us to an answer to this riddle. And a lot of work has been done in each of those areas.

The board this week, as a group, spent a lot of time, many hours this week, testing, proposing and discarding scenarios. Now, by that I mean, individual little pieces of scenarios; relatively detailed discussions.

The purpose of these hours that we spent together was not necessarily to find the scenario that caused the orbiter to fail--we're not smart enough to do that yet. But we did want to determine what tests would be necessary in order to either prove or disprove a scenario. In other words, if somebody has a theory or a scenario which seems to be relevant, then we want to develop what it takes to either prove or disprove that.

And so we went through that--we spent a considerable number of hours going through that process. And I don't have--we don't have an answer for you, so I'm not going to--I won't go into any more detail than that.

The public hearing I found to be very useful. We're going to continue with the public hearing process. The next public hearing's on Monday afternoon, next, and Tuesday morning. We're going to go for three or four hours on Monday afternoon and go for three or four hours on Tuesday morning here at JSC. It's actually going to be at the Clear Lake Hilton Hotel in one of the ballrooms there.

We're going to discuss investigatory matters. We're going to have some of the experts on thermal and aero-analysis come and brief us with charts and view graphs and movies and videographs as to exactly where they are. So you will get a post-graduate level education on aerodynamics and thermodynamics. So you will see--you will be able to tell at the end of that exactly how far we've gone, how deep we've gone, but also how much further we have to go.

We worked--another issue that the board worked very hard this week was the issue of debris testing. We and NASA have had several meetings. The board has some testing initiatives that we want to get started. Just laying the debris out on the floor is not enough to find the answer to this mystery.

We need to do metallurgic testing, we need to do heat testing. There's a whole lot of kinds of--whole series of tests that need to be conducted.

But at the same time we have to be very careful that we don't in any way disturb or remove anything that might be evidence.

So this has been a very careful, methodical process between us, NASA and the people who are helping us, like the NTSB and other people that are helping us like that.

The last thing I'm going to mention is three new members that I announced last week. Dr. Sally Ride has already been to work. She was here last week and has already made a significant contribution. Dr. Douglas Osheroff I've been in contact with. He will be visiting us this week. He already has a bunch of ideas that he wants to pursue. And Dr. John Logsdon and I have exchanged a couple of telephone calls, a couple of e-mails, and I will be meeting with him next week.

So, all three of the new board members are either on or already participating, either in person or by remote. And essentially from now on they will be coming and going essentially weekly, if they can, to participate and help our investigation along.

That's a quick summary. Let me throw some facts out--just some facts and figures.

From--as of close of business last night we had collected 28,286 pieces total that are at Kennedy. We collected thousands more than that. Kennedy has 28,286 pieces, of which 25,404 have been identified.

Now, only--when you see pictures of the floor and see pictures of the grid, that represents only 1,038 pieces of the 25,000. Because you got to remember that we are laying the orbiter out in two dimensions, not three dimensions, upside down. So we're looking, what we're interested is the bottom surface. So that's what--those are the 1,000 pieces that we have out there, the landing gear, the landing gear door, the tiles, elevons and things like that.

All the rest of the pieces are catalogued and stored, and they're available for us to use for analysis.

The 28,286 pieces represents 39,300 pounds, I haven't divided that into the dry weight, but it works out to something like 18 or 19 percent.

On a daily basis, every day of the week, there have been over 4,000 people out collecting debris. On one day last week--I think I'm looking at the 7th here--they had actually 5,300 people out on one particular day.

They continue to average a dozen aircraft a day, helicopters and fixed wing. The Navy team in the two lakes, the Toledo Bend Lake and the Lake Nacogdoches, have identified over 200 submerged targets which are of great interest by electronic means, by sonar means, and then they're going to go back and dive on them.

We're hopeful included in there are the main engines, and I think that that's kind of all the h's.

Oh, yes, the--laid out in the grid among the 1,038 pieces laid out in the grid, are 233 that are from the left wing, which, of course, is what we're most interested in.

And I think that covers, kind of, all the introductory things, and I'll pass it now to General Ken Hess.

HESS: Good afternoon. Group Two is continuing on its march through the basic processes that got the shuttle into the launch that had to do with training and payload and operations.

Now, if you recall from our previous sessions with you, we, kind of, described our approach as, kind of, in phases. We're, I would say, maybe two-thirds of the way through Phase One, and that's just understanding and appreciating all the processes that lead to a launch.

This last week we finished looking at the training and certification, as well as complete research of the impounded records that NASA had on hold for us. And in the payload area we've completed our documentation review and we've looked at the telemetry that had to do with the payload and everything that was down-linked to NASA, and we didn't find anything that was unusual in those areas.

In the areas of operations, we are continuing our look into the DOD request for imagery; we are sharing that with Group One, and also with Group One we're looking at the e-mails that were exchanged between engineers, as well as looking at the impounded records and logs of the mission control team that was at the Mission Control Center at the time.

And this last week saw us begin our initial sets of interviews with the Astronaut Office.

In the area of mission management we've started to take a look at NASA's organizational structure, and those actions and decisions that led to launch preparation and launch decisions, as well as the things that took place while the shuttle was on orbit.

And we'll begin taking a look at the MMT specifically, it's organization and performance, here in the coming weeks with the addition of Dr. Ride to our team.

Last week, I had the opportunity to go to Kirtland Air Force Base as part of the Air Force Research Lab and got to the Star Fire Optical Range, and if you'll recall they took the picture of the orbiter overhead, that--where people have been suggesting, perhaps, that there was leading edge damage that was in that picture. And we're trying to verify that.

And I went there because I wanted to understand the techniques that were used to take that picture, and also to find out what kinds of things have been done to enhance that image by the Department of Defense.

I mean, I must tell you that those photo experts are just now beginning their work in liaison with aerodynamics experts and plasma experts to try to see what the picture will really yield. But the important part right now is to enhance the photo as much as can be done without adjusting the facts behind the photo. And we have an excellent team that's working that process right now.

The team added two new members. Admiral Gehman mentioned Dr. Sally Ride. She's going to be joining our team. And she's going to concentrate mostly in the flight readiness review and certification processes, as well, I think, as pinch hitting in other groups and areas where she has tremendous expertise.

We are also adding tonight, Dr. Tracie Dillinger (ph), who's a human factors and organizational psychologist. If you look in the McDonald's (ph) independent assessment, you will find that she was part of the human factor's group in that particular report, as well.

Now, in the very near future, we are going to be attending an integrated simulation training between astronauts who are preparing for a mission and their ground team so that we can look at all aspects of that training. And I think that'll be probably the last piece that we'll look at as far as active training processes.

We are beginning to outline our approach to taking a look at the safety organization and processes in the next week or so. And then, several members of the team will travel to D.C. this next week to begin interviewing at NASA headquarters those people who are in our area of responsibility.

Dr. Dillinger (ph) and many others who are already on the team, to include a Ph.D. from the NTSB, will join us in coming together with a strategy to begin looking at human factors.

I think everybody realizes that our whole investigation will fall short if all we do is concentrate on the technical aspects and ignore the organizational dynamic. And as you recall, Dr. McDonald, last week, says he had great confidence that the management would make the right decisions if they had the right information, OK? So we're going to take a look at the organization dynamic with an attempt to try to understand the implications of what Dr. McDonald was telling us.

And our goal still remains mishap prevention by identifying the hazards and coming up with risk mitigation strategies that would be helpful. So we'll look at the processes, and then talk to the personnel both in maintenance with General Barry's group and on the operational side with Group Two, and then work the seam of that issue together.

And in the coming weeks, we expect to finish Phase One, and then basically use safety and the human factor processes, being our Phase Two approach to the overall investigation.

As a member of Group One, right now we have General Duane Deal, who's down at KSC right now. Admiral Turcotte will leave tonight to go to KSC. We'll follow up that with visits to Michoud. And we plan to also, next Tuesday, visit the vendor for the RCC. And also follow up with General Hess' group when we head up to headquarters at NASA to do some interviews.

As you remember, our group is responsible for maintenance, materials and management, human factors kinds of considerations also. We've got a number of subteams out right now that are going on, continue their investigation, at least two to three investigators for each subgroup.

I'm going to give you a couple of updates on maintenance, and then I'm going to follow up with material. So let me just cover the maintenance to begin with.

Close out on fault trees is progressing at a pretty good rate. We continue to work the issues that will eventually be categorized as nonfactors. To date, we are closing out on the fault trees, probably in about a week. That still has to be a formal presentation to the board. But we expect to see the SSME, the space shuttle main engine, the SRB, solid rocket booster, and the replacement on the solid rocket motor. So we expect that to be probably be done in the next couple of weeks. And we'll give you updates as we go along that. Nothings been finalized yet on the close out, but right now, to date that looks like a pretty good schedule.

The external tank will take a little bit longer, because right now there are 14 working groups and about 3,200 blocks on their tree and, of course, the orbiter. So we still have a little bit of work to do on that one. So that's the update on maintenance.

Let me just turn to material. If I could have the first slide, please. I'm going to show you a couple of slides here, some of which you have seen before. This is the bipod that I think you've seen before. Right now, we're trying to follow the foam. And here is the connector, as you can make the comparison between what the slide has and what we have that Woody's (ph) holding in his hand.

I will also tell you that as we follow the foam, we're also looking at the fact that 1893, which was the external tank involved with Columbia, was mated, demated and then remated. And there was a problem report generated on that on damaged foam, which is not unusual when that happens, visibly inspected and concluded that there was no problem.

Also, I want to bring to the attention is, this is what is underneath the foam. There are three kinds of gladed (ph) material. And we have examples of it up here that you can take a look at. This is like cork, if you want to think of it that way. But part of this is clearly going to be an issue in so far as cryo-pumping (ph) is concerned. We're still looking at that as an issue.

Now, cryo-pumping, as you remember, is when we have liquid nitrogen or trapped air that liquefies when it's cold.

And that's what happens when it's sitting on the ramp. And then when it launches, of course, we have the fuel being transferred inside the external tank and we have trapped gases that eventually need to be what they call flash evaporated. And that can expand rapidly and break foam, break ablative and break TPS, thermal protection system, bonds.

So these three kinds of ablative material that you see there, from our investigation to date clearly shows that questionable whether it's even needed. And, in fact, the alternatives that are being designed by NASA right now do not include the ablative material underneath the foam.

There will be some changes to this bipod. You can see that a lot of it's at a pretty strong right angle. They're looking at making it more aerodynamic, and they're considering what exactly is--how they're going to pack the connections underneath so they can maintain the integrity of the system.

I want to give you an update on RCC. And this is, as some of you have seen, the quarter-inch complete RCC that shows you not only the fact that we have a sealant on top, but also that we have a silicone carbide coating on top of the carbon-carbon. You go to the carbon-carbon with another silicone coating, and that is a quarter of an inch. That is really what is protecting the RCC.

One of the things that we're looking at is the issue--here's an Atlantis panel where we've had some problems with pinholes and what I'll introduce as some of you have heard before oxidation. Oxidation is when you have a void underneath the surface and a void in the surface that translates down to the lower levels--a void or a pocket, if you want to think about that, as you can.

Here we have an indication that Atlantis--where they found a defect. When they went ahead and did further analysis, this is what we call a CAT scan, an X-ray. You can see where the--not only the surface but also the sub-surface shows some problems.

Now, this is one way of looking at it besides a visual inspection. Let me introduce another one. This happens to be what they call thermography. If you'll hear the term "tomography," that has to do with CAT scans. If you hear the term "thermography," it has to be a flash of heat on a surface and as it cools down, you get an idea of what's underneath it.

This is that same panel. It happens to be a repair that went bad. And you can see clearly with area three and four that those show some voided areas as well as area five.

Now, I introduce this as not the answer on how to do this, but I know NASA is looking at trying to validate this as a probable way of doing nondestructive examination of this really vital piece of the orbiter.

I want to also show this one. It's a little bit of a side cut on another panel that was discovered on the Discovery. And you can see where the carbon-silicon carbides on top and then also that we have the, kind of, a grayish crack and underneath that is a void. If you do a visual or you do a tap test on this, maybe it will penetrate, maybe it won't. But clearly we want to explore the options of improved capabilities for MDE (ph). So that is thermography and also the issue of oxidation.

Day-2 (ph) debris, I also want to mention is being analyzed at Wright-Patterson Air Force Base. We are doing radar signatures on a number of items from tiles, RCC blanket ice, horse collars and carrier plates to get some comparative signatures that we can maybe get some idea of what it is that floated off on the second day. Now, that's proceeding rapidly.

We also have what I would characterize as an interesting aspect on ascent. On ascent, what you try to do is measure the winds on liftoff. They send a balloon up and they figure out where the wind sheers are. The wind sheers allow you to make a prediction in the software on how the orbiter ought to roll or the power ought to be adjusted to transient through any wind sheer. We have an issue with that that we're looking into, and I just wanted to share with you all.

The bottom line is, as we move to understand that, at 62 seconds on launch we saw one of the larger transients we've seen on the solid rocket motor. It was well within parameters, but, interestingly enough, the two largest ones we've seen on ascent both happen to be Columbia, both happen to be going on 39 degree inclinations, both have lightweight tanks. So we're trying to identify if there's any commonality there as an additional stress load on the left-hand side of the orbiter, because it was on the left solid rocket motor that had this input. Again, well within parameters, but just one more as we follow the foam, as we follow the transient stresses on the orbiter that might have been able to contribute to one more issue as we trace down this detective story.

WIDNALL: (OFF-MIKE) along here to report on the activities of Group Three. Our chairman, Jim Hallock, is back at our offices. And he's working on the fault tree analysis of the (inaudible) failure that General Barry mentioned. Scott Hubbard and Roger Tetrault are at KSC today--actually they'll be there much of the week--basically analyzing debris and, kind of, postulating what kind of chemical and material analysis would yield important facts about that debris.

We expect to be joined later this week, as Admiral Gehman mentioned, by Dr. Douglas Osheroff, who's a Nobel Prize physicist from Stanford University. And so we'll work him into the group.

So I suppose I should ask the question, what have I been doing? Well, last week--last Monday, I went to KFC to examine the debris, and looked at some of the damage that occurred in flight.

As an aerodynamicist, I'm paying particular attention to the flight profiles, the temperatures, dynamic pressures on the vehicle.

I'm really gratified. I've been contacted by so many members of the scientific and engineering community who have provided important data relative to our charge. And let me just give you two examples out of the many inputs that I've received.

I guess we have a visual on the first one. It deals with the question of the NEXRAD Data System, the weather radar system. You may know that our country is under constant weather radar observation, and--do we have a visual of that? We don't have. OK, well, let me show it to you and it'll be on our web site.

I received an input from a meteorologist who was a research scientist at the National Center for Atmospheric Research, and also spent some time at Lincoln Lab. And basically the question that the picture raises is, is there any useful data that could be obtained from the NEXRAD System during the period of time of interest.

So I've gone back to this individual and we're working up a, sort of, search for the data in the national data base, and he's going to try to put together a set of, sort of, snapshots in time of what the NEXRAD System might have picked up.

Another example: When I went back home on the weekend I was able to engage in some very profitable brainstorming sessions with colleagues at MIT, really on a moment's notice. They were very forthcoming.

One of the issues we got into was to talk about the thermal environment seen by the vehicle and by its structure, and the properties of aluminum at very high temperatures. Without its oxide coating, aluminum is a very reactive material, and when it's exposed to high temperatures and a high-speed gas flow the possibility exists of vaporization of aluminum, which could be followed, then, by a very rapid burning of aluminum vapor. That's obviously a scenario that we want to follow up.

Our group is examining many scenarios. Some of these scenarios focus on the leading edge of the wing. Reconstruction of the flight conditions from flight data indicates the development of increased aerodynamic imbalance, which appears to be located on the left wing.

Some of you may know that NASA has begun a set of wind tunnel tests to determine what kinds of postulated damage on the wing leading edge could explain the level of imbalance. It turns out that a single missing tile or missing panel at the leading edge does not explain the measured effect. So, obviously, a series of wind tunnel tests will be run to determine what extent of damage is needed to produce the observed imbalance.

Our group has been focusing on the initial damage that was caused by the foam that impacted the shuttle wing near the leading edge, so I have a short video that shows this debris impact. It's about a--what?--four-or five-second loop. And it'll keep running it. And, obviously, what you want to look at is the piece of foam that comes down, impacting the leading edge.

You see the white? Where it is? There it is. I mean, you can see it. Right in there? You see, there's a--I mean, the video gives you a sense of motion. Obviously, the stills that one could get out of this could be a little higher quality. It's a very difficult thing.

But I think our group is convinced that that foam impacts the shuttle on the lower surface near the leading edge, and basically pulverizes, turns to powder. And so, obviously, we're very interested in this.

I'll say something else about that loop there. The, kind of, amateur interpretation of that loop there, you only see one piece of debris, but other photography indicates that there's more than one piece of debris.

The second gross level interpretation is that that piece of debris appears to hit on the leading edge, as Sheila Widnall just said, but on the lower half of the RCC; in other words, the debris doesn't appear to go over the top and under the wing. All the debris appears to go under the wing. So it appears to hit the leading edge, but, kind, of on the underside of the leading edge, and then all the debris follows the wind pattern.

And it appears to hit at RCC panel six, seven or eight, no closer than six, no more than eight, which, unfortunately, is not visible on the on-orbit photograph that we have. It's too close in, too close in.

And as you see, after the debris goes by there's no missing tile. I mean, you know, nothing's missing, so once again we had these tantalizing little pieces of evidence that don't fit together.

QUESTION: You mentioned at the beginning about scenarios that you now have tossed out. Can you expand a little bit on which ones you for sure (inaudible)?

(UNKNOWN): I don't know that I want to get into specifics of it, but what we are attempting to do is to take these broad scenarios that we have like hot gases got into the left wing somehow, be a little bit more definitive as to what could happen--remember, we can't prove any of this--and if they seem plausible, then what kind of tests do we absolutely need to do to either prove it or disprove it.

You know, one of them is--one of the scenarios might be that this had nothing to do with tiles or RCCs, that the heat got in there another way. There are some indications that there were some fuselage temperatures that went off temperature. So the--one of the scenarios might be that heat got in there another way. OK, without in any way evaluating that scenario, we then say, "OK, now what kind of test, what kind of data would we need in order to bring that one home?" just as an example.

So what we're attempting to do is to take what has been a very, very broad and open and not fenced investigation and we're attempting, as I said last week, you know, we're trying to pick up the pace here a little bit. We're attempting to focus a little without leaving anything out.

So I wouldn't want to get into its specific scenario because whichever one I mention will--you know, will become the favorite of the day. And we don't have a favorite scenario.

WIDNALL: I guess I almost want to ask General Barry that question. And in our group is you know, a lot of what the three groups are doing has a lot of overlap. And I think in the materials and the operation, it really is a lot of overlap.

We, for example, are monitoring and may run some tests of our own to see what kind of damage is caused by foam impacting, you know, a set of tiles or some RCC. I mean, that would be the way that a, sort of, technology group formulates the problem. The question of what do we see in the video, what do we see in operations, what do we see in materials is almost an issue that's shared between two groups.

BARRY (?): I'd like to comment on that. We've sent the original photographs and film to a commercial expert. We've got some of our experts at Kirtland who are working this right now. And what they are trying to do is figure out, through spectral analysis, whether that is--that splash you see coming off the wing, if I can use that term, is foam, is it tile, is it ice? Is there any metallic elements in there? There's going to be a very tedious process to go through that. And they're working very hard in the last week and a half to be able to do that. So we expect to see some results very shortly.

But it's an excellent question. And that's the process we're going through to get to it.

QUESTION: Can you tell us whether any of the panels six, seven or eight that appear to have been hit in that film have been recovered? And what--if there's any tell-tale conditions on them?

(UNKNOWN): I would have to take that question to be specific. But in the left wing we have recovered a piece of almost every RCC. Now it may be a mounting bracket or something like that, but I believe that we're only missing two or three of the total number of RCCs from the left wing. I don't know if anybody wants to help me with that, but the guide--but to get to your specific question, we'll get back to you on that. But we have recovered some part of almost every RCC panel in the left wing. But so far we have nothing on the left wing--if we had something on the RCC on the left wing which related to this video, we would have told you that immediately. No, so we don't have anything exciting about that.

QUESTION: My question has to do I think for General Barry on the blips here you saw at 62 seconds (OFF-MIKE) How does this play in to what you're looking at? That's interesting as though it might be one of the series of events that happened on this particular mission that played into it. (OFF-MIKE)

BARRY: I've been doing the analysis and trying to figure what was different about this flight. We're trying to pick on anything and everything that stands out as different.

This particular incident had to do what they call the absolute angle. It has to do with the amount that the solid rocket motor moves to be able to (inaudible) either roll or turn the orbiter. This is a software program input that is done on the ground in order to counteract what they know to be a wind sheer up top. What's interesting is this one was the highest and the closest to the max dynamic pressure point that they had on flight.

Now, what does that mean to the mishap? We're looking at this as just another additional stress load on the orbiter on ascent. Now, does that mean that there are anything that contribute to the mishap or are our foam? But this is at 62 seconds. We know the foam that we think came off from the external tank--and we're still, you know, clarifying what exactly that material is--came off at 81 seconds. So we're looking for any of these abnormal--not abnormal--anomalies that might stand out as making this a different aspect. So stress load and stress factors and what we call high (ph) loads also are some of the things that we are looking into on this ascent.

QUESTION: Could you just clarify that, when you said this is the most extreme or the second most or--do you mean in all sub launches or some other period of time?

BARRY: What we looked at is what is common. You know, all the shuttles do to different inclinations. They have different external tanks, in some cases lightweight, super lightweight. It turns out Columbia had the two that stand out.

And I can go over this in a little bit more detail with you on slides after we break up. But clearly the two that stand our are STS-90 and 107. And both of them were at 39 degree inclinations. Both of them had lightweight tanks. Both of them were Columbia. And we're just trying to see if there's any kind of a common thread there that might lead us down a path that could give us some kind of an insight into the stress on the orbiter.

Earlier there was some discussion about the breach in the wing, plasma breaching the wing. Has there been any analysis done on the debris that gives an indication where the plasma may have initially--the location where it may have initially breached the wing?

WIDNALL: Well, I think examining the debris down at KSC, I think one sees several interesting things. One sees melted aluminum slag on some of the interior sections of the RCC panels. One sees some very suggestive patterns in some of the tiles and some of the metal around the wheel well. It really is a detective story. I'm not ready to, you know, make any final conclusions about it.

But the debris is really reflecting the heating and aerodynamic load that it saw. So I think there's a wealth of information in that.

WIDNALL: I would say nothing definitive. Again, I don't think we want to leap to conclusions too early on this. There's going to be a chemical analysis and material properties analysis.

And, of course, the whole question is, how can you analyze that without destroying the piece? So there's a whole question of what sample size, you know, can we use to get the data without destroying the piece. So that's a really important question.

QUESTION: To follow up on that, Dr. Widnall, is what you're seeing giving you any further indications as to whether gas was escaping out or coming in at the left wheel well?

WIDNALL: Well, you know, I'm sure everybody has their favorite scenario on that. The scenarios that are being examined are really a balance, you know, between damage to the leading edge, damage to tiles.

I guess when I think about everything that's being examined, I would say the bulk of those show hot gas going in upstream of the wheel well and exiting in the wheel well. But I don't want to be categorical. There may be some other scenarios that are being examined that have other features.

(UNKNOWN): Everything helps. I've been over the time line, kind of, line by line myself, and I didn't see anything in there that struck me as being very revealing. A lot of times the more data we get the more it confuses us rather than help us.

But I didn't see anything in the latest revision of the time line. And I'm fully aware of all the issues about the data element that seems to indicate that the stick had been moved.

And there's another one which we are also puzzling over. It's a few seconds before that. I think it's in the first five seconds. It shows a master alarm--a master warning light, which, of course, would have been seen in the cockpit. But the data is not able to attribute what caused the master alarm to go off. So that's interesting, too. Could have been any one of a thousand things by this time, because it's at loss of signal.

QUESTION: Back to the time line--and by the way (inaudible) it's a marvelous document for insight and for questions, especially the very first page, which talks about the earliest known off-nominal external event. It's event sequence number 21 and 21.5. The earliest known off-nominal external event having to do with, first, a left yaw followed a few seconds later by a right yaw, presumably stopping the left yaw motion.

I don't understand what this earliest known external event, off-nominal event is. Is it just the RCS firing or what caused the RCS firing? And do we have any idea why the RCS jets fired at that time?

(UNKNOWN): Actually we don't have any real conclusions on that, other than as we work through the whole time line it becomes apparent that the shuttle, working with the digital flight controls in auto, is compensating up until the very end for the yaw rates that are starting to come onto the shuttle.

QUESTION: And that's occurring with a Q-bar (ph) of under 10 PSF (ph)? How big of a drag, do we have any idea, would that be? Is it a one-or two-square-foot irregularity or is it bigger or smaller?

(UNKNOWN): This is part of the investigative process that's ongoing. You know, they'll actually working through the structural scenarios like this so they can have a full understanding about how much of a problem would have to be present to cause the shuttle to react down the path that's laid out in that chronology that you have there. And we're just not there yet.

It's a very good question. And last week I mentioned that one of the things that the time line had demonstrated to us was the impression that things were happening earlier in the reentry than we previously had been given to understand, what you are looking at there.

To me, the question that I take away from that is, even though I understand that yours is a very good question, but to me what it gets to is the question of, which started first?

In other words, did the thermo event cause loss of tiles, and thereby these aerodynamic forces, or did we lose an aerodynamic surface, which then allowed the heat to start unzippering this aircraft? And every time I think I've got it figured out, I get a piece of data which changes my mind.

If the aerodynamic surface were disturbed long before re-entry, well, that then leads you to believe that there was some physical misarrangement on the wing that had nothing to do with entry.

On the other hand, all of our photographic evidence indicates that if there was a physical misarrangement on the wing it was so tiny that it's not visible to anybody else, which would lead you that it was some kind of a thermal event which was the triggering event which then started the unzippering process. And so, the fact that the orbiter was fighting an aerodynamic misarrangement earlier than we previously had thought, it makes my riddle very intriguing, OK?

WIDNALL: I mean, I actually, you know, just returning from Cambridge. I haven't really had a chance to study the time line. But you know, it could be one of the situations where the commander leaned on the stick and it would go (inaudible).

QUESTION: Dr. Widnall, could you go into greater detail about what the wind tunnel tests have shown?

WIDNALL: Well, I mean, it's really quite straightforward, and I got a briefing on this.

NASA put a model of the shuttle with a little notch out of the leading edge and measured the moments--the aerodynamic moments. And then compared those with the basically guidance and control analysis that backed out of the flight data what aerodynamic forces must have been acting on the vehicle in order to produce the observed flight behavior, the reaction jets and all the things the vehicle was trying to do. And so out of that analysis is inferred the aerodynamic forces and moments that must have been acting on the vehicle during the last part of the data where the aerodynamic got really serious.

And so they tested the shuttle in the wind tunnel with a notch out of the leading edge. And they found that the--basically, the moment coefficients were--they had their sign right--but the magnitude was about four times smaller than it needed to be. So the obvious thing to do is to--and they will do this--to go back into the wind tunnel and remove more sections from the leading edge and see at what point do you get moments that are comparable to the calculated moments from the guidance and control solution.

QUESTION: Just to follow-up, do you have an idea of how big that notch was (OFF-MIKE)

WIDNALL: I believe it was equivalent to one panel. So roughly speaking, we'd be looking to take four or five panels out of the leading edge, roughly speaking, in order to reproduce the observed flight characteristics.

QUESTION: I'm sorry to keep going, but it went on a curve. What point on that curve are we looking at? At the maximum at the end, or...

WIDNALL: Yes, well, I mean, this was--basically they have data for the entire flight trajectory, up to the point where they had lost their signal. And so, they can back out the aerodynamic moments and relate them to--they know the vehicle attitudes. They can relate it to the vehicle attitude and they can calculate basically the moments that existed on the vehicle. So they can back out the effective vehicle trajectory.

QUESTION: For the admiral, you mentioned that the piece of debris we see in the video is not the only piece of debris that you've--you're aware of. Could you tell us what you're either photo documentation or other evidence has shown you about other pieces coming off during launch, where they might have come from and whether they hit the vehicle?

GEHMAN: From other camera angles with a little bit more sunlight, most photo analysts think that there were a total of three pieces of debris. This is the largest one. In this angle--and by the way, they're all clumped together and they all hit the wing at the same time. So you can't tell whether--you can't tell piece by piece how each one acted from the photography.

In this particular angle, it looks like one piece of debris, but it's all one event. In other words, they all come off at the same time, they all followed the same path, and in one or more of them hit the underside of the wing.

From other angles you can see what appears to be debris number two and debris number three. And they all fly the same path. So you can't discern anything out of it. Now whether or not two of those pieces is foam and one is ice or whether they're all foam with ice on it, I mean, we can't tell that.

But I mean, I just wanted to make sure that the record didn't seem to indicate we're changing our story about three pieces of debris. That's still a good, valid analysis.

QUESTION: For Dr. Widnall, I wonder if you could talk a little bit about this issue of boundary layer prohibitions.

QUESTION: Do we know if Columbia was experiencing that transition at the time of the accident? And how big a factor might this be?

WIDNALL: OK, well, at the same briefing that we had on the--basically the aerodynamic affect and the size of the R moments (ph) and the wind tunnel tests that were done on the single panel missing, roughly speaking the--I'm going to get this wrong--asymmetric boundary layer transition--more boundary layer transition on one wing than on the other wing--produces a moment that is roughly comparable to one leading edge panel missing.

In other words, it is roughly a factor of four smaller than the observed asymmetry in the moments, due to whatever damage existed on the wing.

So even if you had a symmetric boundary layer transition, it appears to be a factor of four too small to explain the size of the moments that existed on the vehicle.

WIDNALL: Well, I don't want to rule anything out, but it does not seem to be of the magnitude that was measured in flight.

QUESTION: Maybe for Dr. Widnall: Just to clear up a little bit what the wind tunnel analyses, combined with the data from the flight show--I mean, is there some kind of convergency you're seeing in terms of you think that the debris hit in this, on a sense in this defined area of the RCC and it looks like you maybe need one or more RCCs to come out of the left side of the wing to produce the effects you saw on descent?

I know you haven't settled on one theory, but is there a convergence that you're seeing in these different pieces of evidence on pieces of the RCC on the left wing?

WIDNALL: Well, I'm not going to settle on a single theory, but I've looked at the data and I guess from my point of view what I see is a heating event followed by a very rapidly developing aerodynamic event. And I think the Guidance and Control Group has done a really good job at backing out those aerodynamic forces.

So, you know, the aerodynamic event, when it occurs, is pretty dramatic. And I mulled over that for a while and I looked at the flight profiles and I realized that the aerodynamic event occurs at the time when the dynamic pressure is undergoing a rapid increase of roughly 30 percent.

Now, that makes sense to me that the vehicle was, kind of, coasting along with heat damage, and then there was a sudden increase in dynamic pressure that came from the flight, and that was the onset of aerodynamic--the aerodynamic event. And that makes sense. But I'm not going to speculate.

QUESTION: Yes, just to follow up on that, can you say when in the time line that aerodynamic event was at its maximum?

WIDNALL: I'm having trouble hearing you, but, I mean, it--there is a point in time where the guidance and control analysis indicates the onset of a rapidly increasing, I hate to use the word yaw moment, because it's so technical, but that's--it's the twisting moment on the vehicle.

(UNKNOWN): Right. In other words, as the vehicle reenters the Earth's atmosphere, there's a time when the aero forces start going up more rapidly than a straight line and, lo and behold, at that point the orbiter starts to exhibit non-aerodynamic tendencies; remarkably more.

QUESTION: Have you done any analysis, or are you having any analysis done, on the heating from the videotape of the crew to check and see what was burning on the outside, if it was just nitrogen, oxygen? Have you done any analysis in that area?

And also, in your theory of the leading edge, I understand that the first four panels were pretty well badly damaged, you only have the supports of those, and then if you have panel six, seven and eight, that's getting to the area, possibly, of where you have enough to give you this type of aerodynamics that you've been talking about.

WIDNALL: OK, well, those are really two separate questions. Let me take the first question.

My understanding from the crew video is that what was observed on the video was completely normal, completely expected. It is the normal flashing of plasmas that occurs--what?--some five minutes before reentry into the atmosphere?

WIDNALL: So, again, I'm not discounting anything, but I think that is not connected to the later events.

Now, the aerodynamic--I've, sort of, lost the train of thought on your aerodynamics question.

QUESTION: Well, I was just saying, Doctor, that I understand that the first four RCC panels, that you only have small pieces of them but you have a lot of damage of the supports there.

QUESTION: Now, if you have those four opens, open on six, seven and eight, don't you have enough there to give you the aerodynamic drag that you were anticipating?

But, again, I think one has to go through that scenario very carefully, look at which underlying support structures are severely heat damaged, look at the condition of the individual panels that we do have, and really sort that all out.

(UNKNOWN): And we have to compare the left wing to the right wing. It may be that the right wing in-board support structure in RCC may show the same type of heating, in which case the deformations we see in the left wing would be break-up deformations, reentry deformations, rather than the accident cause deformations.

But you're--the underlying understanding in your question is correct. The left wing in general, the pieces of the left wing show more trauma than the pieces of the right wing.

QUESTION: This question is for General Barry. Can you explain something to me just so I'm sure I can understand it, can you explain to me--you said as we followed--no, sorry, you said that the, yes, the ET-93, the external tank, was mated, demated and then remated, and you said there was a report on damage found, it was visually inspected, concluded there was no problem. Can you explain to me what you're talking about there and what time frame this was? What does that mean? Can you clarify?

BARRY: Right, in the fall time frame the external tank was mated to solid rocket boosters. It was subsequently decided that those solid rocket boosters needed to be moved to another mission, so what happened was the external tank was demated and then remated onto Columbia.

So this is something that has happened before, as I understand it, but clearly you have to follow the issue on the foam. A problem report was generated, as you mentioned and I stated earlier, which required a follow-on inspection.

The concern we've got right now is just to see that problem report which we've already investigated and see if there's any more follow-on information that can help us understand cryo-pumping, maybe some additional cracks that might have been in there, we're trying to look at after, or just before last inspections on launch to be able to make that determination.

So, again, as we follow the foam story here, we're trying to look at each one of the iterations, and this is one of those things that stands out as a little bit different, that may or may not be contributing to the mishap.

QUESTION: I have a question for Dr. Widnall that to some extent relates to the boundary layer issue. I'd like to follow up on a comment made last week by Roger Tetrault.

Last week he said Columbia had flown, I quote, "a very hot reentry," and my question is, compared with most other reentries does the data support that Columbia was, indeed, flying a somewhat hot reentry as Tetrault said?

And if so, does that indicate that Columbia had an early boundary layer transition?

WIDNALL: Well, I have certainly heard that, but I've asked for data on anomalies from some previous flights of Columbia, and I'm going to look at that very carefully.

As I mentioned, the magnitude of the asymmetric boundary layer, in terms of forces, is not large enough to explain the observed aerodynamic imbalance.

But on the other hand, it could cause heating problems, and obviously anything that creates a heating problem can't be ignored.

GEHMAN: We have begun a line of investigation into that. General Barry has some facts over here, which I don't think we need to recite, but generally speaking, as far as time of shuttles being in the period of max heat, other kinds of facts like that, Columbia has not endured any more punishment than any other--than anybody else.

I think what Mr. Tetrault found was, though, that if you look at various temperature instruments, that there are signs that even though Columbia hasn't been subjected to any more punishment than any other orbiter, he found some places where some of the skin temperatures and things like that were higher than other orbiters, and we haven't made any conclusion about that.

BARRY: I might also mention that (OFF-MIKE) information on the history of the transition for Columbia. The transition time in seconds is how they measure it as it makes its entry.

The average for Columbia prior to the mishap was 1,204 seconds at point three, which is about a third of the way down the orbiter, and 1,160, point six, so two-thirds of the way down the orbiter.

The average for the fleet--as I said, for Columbia it was 1,204, the average for the fleet was 1,190; not much difference. For the, what they call XI.6 (ph), was 1,160 for Columbia, and for the fleet average it was 1,173; again not much difference.

GEHMAN: These are in seconds, in the transition zone, it's how NASA measures it. Now, that's what I referred to as far as time is concerned, and we have to find out whether or not even though they--Columbia spent the same amount of time in transition, whether or not she endured any extra higher temperatures. And that review is still going on.

QUESTION: For whoever knows about it, can you address the mystery object that was tracked in orbit with the shuttle? Has anybody done an area/mass calculation, ballistic coefficients, anything like that? And what else can you provide us in terms of information about it?

All we heard was 24 hours after launch it was tracked by radars. Do you have a more precise time or which radar tracked it first? And the time of day when it reentered over the South Pacific?

(UNKNOWN): Yes, this is what I alluded to earlier. We've got the radar signature study being done at Wright-Patterson right now, in the Air Force Research Laboratory, and we've got a number of pieces from the orbiter.

Of course, they're new pieces, so we're going to have to do some examination of what might be extrapolated off of damaged pieces.

But the intent here is to try to compare those signatures off a number of radars, not only from what we had for air traffic control, but also from the Air Force radars that came and gave us some information on signatures.

So hopefully with that comparison we'll be able to maybe put some substance to that second-day orbit piece of material that came by or off the orbiter.

QUESTION: So, General, do you have any more data on the actual orbit of the object, that NASA orbital information group just recently unembargoed the Keplerian elements of--for Columbia. But nothing has been provided as far as the orbit of this particular object.

(UNKNOWN): No, we have nothing new that we didn't release last time. The only thing that's new is this reflectivity and luminosity studies going on to see if we can figure out what the part was by matching it up with known pieces.

QUESTION: I have one quick question for General Barry on the problem report on the foam damage. Where on the external tank was the damage reported?

BARRY: The damage in the problem report was at the bipod. So just as we showed up here and also on the screen. So it was on the bipod region of the left side.

QUESTION: You showed some RCC panels with some voids and some non-conformities in the material. Are you examining whether that is a possible entry without any kind of space or foam (inaudible)?

(UNKNOWN): Well, yes and no. It's possible that some of this damage might have led to the loss of an RCC panel, but highly unlikely.

What we're really looking at is a complex failure of a complex system. It's possible, one of the scenarios we're looking at is it's possible that the foam striking a healthy orbiter would not have done--not done enough damage to cause the loss of this orbiter. But it's possible that foam striking an unhealthy orbiter that had problems in it, either due to stresses on launch--we talked about the wind sheer--too much heating and recoveries of too much heating and transition of the years before, aging of the orbiter like the RCC faults we see, or a whole number of other complex issues, it's possible that you could do some damage to this orbiter that would have been as a result of a normal event which she could have survived at age 10, maybe she couldn't survive it at age 21.

(UNKNOWN): Right now it is Lockheed Martin, and that is what we're going up to see on Tuesday of next week. We're going to the vendor with a team of experts from different variants, both in NASA and outside NASA and from academia. And we're going to go up there and look at...

BARRY: Well, we're just going to look into when you do a O&N, better known as a depot in the Air Force terms, they will look at the RCC panels, identify any anomalies. And if there are, they will send it back to the vendor, all right. And when they do a process flow between flights, same thing. They will identify any problems like pinholes or any abrasions or some kind of corrosion. If that's the case, then they will remove the RCC and send it back to the vendor.

We're curious as to see what kind of testing has been done by the vendor. And we're particularly interested in providing some information on possible recommendations on what NDE profiles, non-destructive examinations, engineering could be done in order to improve the process.

So I mentioned tomography, which is CT scans. I also mentioned thermography, which is the heat one. So we're looking to see if we can provide some additional insight for the board as well as a possible recommendation on where we would want to go for follow-on return-to-flight considerations for the RCC.

QUESTION: General Barry, have you looked at the communication between Space Command at the Johnson Space Center as far as this object that came off the orbiter and flew by? Was there any--maybe I misunderstood early on, that that information was not given to NASA early on? Or was--have you looked at the communication between the two groups? How soon do they know?

BARRY: It was well communicated and well transmitted. So this was something that was very evident early on.

It is not unusual, by the way, to have this happen. Ice has come off. We have had reports from astronauts that screws and washers, even parts of blankets when the orbiter doors are opened, for some things to fly out in there. The question now is, with all the seriousness and obviously with the mishap, was that something that was off the left wing that subsequently was damaged on ascent. So it obviously has a heightened awareness. And it wasn't cited by any of the astronauts reported by in communications (ph). So we have to go back to the detective story of trying to figure out what it is on radar signatures that might help us find out what that is.

QUESTION: Is there any thinking in your mind, after you've been looking at all of this data, of recommendations that may lead to better sensor equipment on the orbiter? If we have another tragedy like this, do you have any feelings early on what's missing in your...

GEHMAN: We're going to issue either preliminary recommendations or preliminary findings as soon as we are content with them. And we--in addition to working hard many, many hours a day, seven days a week of finding out what went wrong with this thing, we're also working hard on the cultural, management, budget issues.

We're also working very hard on the return-to-flight issues. And so all these things are going on simultaneously.

Yes, we have already had a couple of sessions on what could we tell NASA and when. Right now we're not ready to announce anything.

QUESTION: On the nature of the debris, whether it's foam, ice combination, has NASA told you that in their belief that debris contained no ice?

GEHMAN: Let's see; I don't know that anybody's been that firm about it yet. I think that that's still an open question as to whether or not there might be ice in there or not.

(UNKNOWN): This is a concurrent effort that's going on, it's not just a board effort. They are also cooperating with Air Force Research Lab to figure out what it is, and also with Kirtland to figure out what it is on the spectral analysis.

So this is an ongoing effort that we hope to get some results here in the next week or so.

GEHMAN: I mean, it wasn't part of your question, but just to give you an example of why this--we just keep working these questions, we never give up on them. We worked for a long time on the issue of whether or not debris passing through the hot exhausts of the shuttle engines would be like putting a piece of metal in a Bunsen burner. And you would get a color flash depending on what the debris was.

We worked that issue for a long, long time and got a lot of smart people working on it, and the answer is that if it were certain kinds of metal, maybe, but everything else, no: You don't get any kind of a flash.

So, we just never give up on these issues, and so I don't want to indicate that we're not getting anywhere on the ice issue, it's just that we keep picking at it.

QUESTION: General Barry, I have the impression--is this correct?--that you're saying that the existing examinations done between flights on the RCC might not capture flaws that could come back and bite you later in some weird combination or unlucky combination with other factors.

BARRY: No, I'm not exactly--I'm not saying that. What we do have is the evidence of what we've asked for questions on what kind of damage has been done to RCC.

There's six that we have, what they record as dings. One was in STS-39 in '91, 45 in '92, 65 in '94, 89 in '98, 103 in '99 and 102 in '01. All of them are a little bit different, some affect T seals, some are due to micro-meteors, some have to do with impact damage, some were scrape due to large damage that they indicate.

So, we're trying to go back to each one of these and find out was and is the inspection of the RCC adequate enough? We know that they do visual inspections, some at three feet, some closer than three feet, some with magnifying apparatuses to give them better indications.

But what is underneath the sealant? Is there oxidation that has provided some kind of a gap underneath it that we have to be sensitive to?

Now, is this something that contributed to the mishap, as the admiral said? You know, if something hit an orbiter that is not brand new, that's got--and this is an issue that we clearly have to work in--aging spacecraft, OK? We're entering an era we've never been there before. And our space exploration has always been either we had our capabilities to use it for one time, but now the orbiter is getting into 20 years-plus in a lot of cases, certainly in the Columbia's case, and we have to be more suitably attuned to the aspect of aging spacecraft in an R&D environment.

So this is just one of our issues that we will look on as maybe a contributing non-significant--non-factor contributing to the mishap, but something that we want to make sure that we can provide some serious recommendations.

BARRY: No, but you can eat away at it. I guess when you have a pinhole, you can have oxidation occurring inside the carbon-carbon that makes a gap.

We've seen evidence, as the photos that I showed you clearly indicate, with Atlantis and Discovery. Some were attributed to faulty repair, but also some were attributed to--no fooling--after it came back it was inspected and found to be that way.

GEHMAN: Think of termites. No, I mean really, or any of you that are boaters, it's blisters in fiberglass. This RCC is built up in layers, the oxidation gets inside and starts opening up gaps from the inside out.

And so the problem is when you do a visual inspection from the outside you never see it. Just like in a sailboat, or when you get a--or any kind of a power boat, when you buy a boat you get a survey and the surveyor has a little brass hammer, and he goes up and down the hull tapping it, this is one of the things that they do here because you can hear a change.

QUESTION: At some point you're going to know as much as you're going to know from the finding of the debris and so on. Do you anticipate when we're going to quit searching for debris?

I mean, they're still finding things, like at some point when they quit finding things and it's been two weeks and they haven't found anything else, when do you think that's going to happen?

I mean, this seems to be--you're still finding more and more questions rather than zeroing in on any answers?

GEHMAN: As you probably are aware, we've just come off a period of actually very bad weather. And the weather has now actually improved in East Texas and Central Texas.

Some of the debris that we're really interested in is under snow, and we are hoping that when people get outdoors and farmers start plowing fields and the snow melts that more interesting debris farther west will start to emerge.

So debris is still very important to us. I cannot give you a time. This board is going to work as hard as we can for as long as it takes to get--until we have some figure of merit of certainty on this.

QUESTION: You don't have a time frame? I mean, the space station is up there and the clock is ticking on getting the shuttles back in flight.

GEHMAN: But if we don't know anything, we're not going to--we can't say anything. So we're just--I mean, we can't possibly work any harder than we are; we're already working seven days a week. So we have--like I said before, we have either 4,000 or 5,000 people every day of the week out searching for debris; every one of them covers about three acres at a shot. There are divers out there, there are pilots, there are helicopter pilots.

Now, the energy level's still very high, both among the debris pickers-uppers, the debris analysts and this board, and I would not want to put any kind of time frame on it.

QUESTION: This is for General Barry regarding the problem report on the bipod foam area. Do you know whether that concerned the jack-pad close-out or the bipod ramp?

And what was done? And was there a hand patch done? Or what was the response to that problem report?

BARRY: No, as soon as you demate, you generate a program report as I understand it. So that had to be inspected after it was remated. So after it was remated, it was viewed to be OK, and they signed off on it.

Now, the question we've got, you know, as we move these things around, were there issues of cracks or things that could have contributed to cryo-pumping? And we're trying to do some experiments.

By the way, I might mention also, down in Michoud we're going to be doing a lot of experiments with the tanks that we have right now. ET-120 is being looked at this week as a kind of a test case to be able to do some analysis. And we'll do some cryo-pumping analysis and we'll do some foam analysis to see what the cracks are by trying to figure out with some kind of a dipenetrant (ph), water-based--I think it's--they're still working on trying to decide that, to get some kind of feedback what is it that could be happening to that particular area by the bipod.