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Columbia Accident Investigation Board Press Briefing
Tuesday, April 1, 2003

1:00 p.m.
Center for Advanced Space Studies
Lunar and Planetary Institute
3600 Bay Area Boulevard
Clear Lake, Texas

LT. COL. WOODYARD: Good afternoon and welcome to the Columbia Accident Investigation Board press briefing. We will begin today's briefing with opening comments from the chairman of the board, Admiral Gehman.

ADM. GEHMAN: Good afternoon, everybody. We'll use our usual format here today. We have a couple of introductory comments to make. We will let each of the board members speak, representing their group, and then we'll take your questions.

First of all, I would like to thank the Center for Advanced Space Studies, particularly the Lunar and Planetary Institute, whose facilities we're using here again. I appreciate it very much. Thank you very much.

This has been a good week for us, not just because of the promise of data from the famous OEX recorder, which we're going to get into in great detail, but also because of progress on a number of other fronts which we will mention here.

I think it's worth mentioning to kind of remind us all: Today is two months to the day since the loss of Columbia. Maybe it's useful for us to just take a second and reconstruct what we're doing.

The board is essentially working on three fronts simultaneously. The first is to determine the direct cause or the initiating event of this tragedy. As we have mentioned on several occasions, to do that, we are essentially pursuing six parallel avenues of technical investigation, and I have mentioned these before. That's the thermodynamic analysis, the aerodynamic analysis, the reconstruction of the debris and the testing of debris to learn what we can, the building of a detailed time line based on the telemetry and now the OEX recorder, analysis of the photos and the videography that we have received, and analysis of the maintenance and modification documentation. Those are the six areas.

If we find the direct cause because of physical evidence, that would be wonderful; but if we have to infer or deduce the initiating event, what we will do, of course, is to attempt to get these six avenues of investigation to line up somehow. Somebody has once described it to me as getting the holes in the Swiss cheese to line up. Then that, we believe, will point us with some degree of surety toward the initiating event.

The second front that we're working on in parallel with great rigor -- and will hear about it today -- is the investigation into all the contributing and root causes. This has to do with all the issues of budget and management and committees and boards and processes and all of this that's about ageing spacecraft and E-mails and all those kinds of things. We are going to run all that stuff to ground in due course; and it will be part of our report if it rises, in our view, to the level of being a contributing cause. You're going to hear about that today.

Then the third front that we're working on is this context issue that I had mentioned before -- that is, we're going to put our report in context. By "in context," I mean that this accident, in our view, is not necessarily a random data point on a continuum graph. It probably fits into some kind of an overall context. That context could be the context of budget patterns. It could be a context of changing priorities. It could be the context of perhaps the psychology of continued success. It could be the context of work force patterns -- that is, it could be that the work force has changed or the way they look at the shuttle program from being an operational or a research and development -- a whole number of contexts that we will attempt to put this accident in, and it will be part of our report. Several members of Congress have indicated to me that their work just begins when our work ends, and so we've got to provide them a document which will be a smooth bridge into the things that they need to do.

That's really all I have. I want to get to the meat of the press conference, which is listening to my colleagues here on the left. We'll start off with Steve Wallace, who is in the group we call Group 2, which is basically called the operations.

MR. WALLACE: Thank you, sir. So following Admiral Gehman's three fronts, I think we are largely in the second front in Group 2 in terms of contributing on root causes. The two gentlemen to my left are a little more into the debris and hardware, and we're more focused on decision-making and processes.

Let me just first give a quick report on where my colleagues are. There are three board members assigned to Group 2. Major General Ken Hess is at the Marshall Space Flight Center this week. He'll be doing a series of interviews and inquiries relating to external tank issues, particularly disposition of falling foam events in earlier flights and their role in the Flight Readiness Review and Certification of Flight Readiness process.

Dr. Sally Ride is the third member of our group, who is just this week kind of off, closing up some other personal commitments from her past life before Admiral Gehman drafted her to join our board. So she'll be back with us next week. I will say we worked with her for a couple of weeks before and she is a very effective and valued member of our team, especially on issues of communications and decision-making, obviously brings a terrific historical context and a great deal of technical expertise, as well.

I'm going to talk about foam a little now. Our part of the foam, again, is largely the decision-making on the disposition of prior foam events and we are doing what we're sort of calling foam audit where we're looking at falling foam throughout the history of the shuttle program, both when it was sort of popcorn and falling and then different events and particularly, of course, issues of bipod ramp foam and a particular focus on STS 112 where there was a substantial piece of bipod foam and the sort of disposition of that and whether there was a tendency to sort of normalize falling foam, it happens all the time, or whether it needed to be a distinction between the sort of popcorning small pieces of foam that was addressed a long time ago and these later issues. I will say we've reached no conclusion on foam's exact contribution. There's testing going on this week under Mr. Tetrault's group, or in the near future will be some testing to determine the possible foam impacts on different parts of the TPS system.

The other issue that we're heavily involved in is the request for DOD assets, the much-discussed on-again-off-again requests for DOD imaging. That's largely the subject of all the E-mails that have gotten so much publicity. I'd like to say about the E-mails that they are important but they are one part of a very complicated story. Other parts include interviews which we have done, over a hundred by this board already. In a great number of those, some of those same issues that are in E-mails are discussed -- minutes of meetings, various logs, audio recordings of meetings, comparing those to the minutes to try to get a sense for the dynamic. Mr. Tetrault will be talking later about all these various sensor inputs, sensors that were downlinked and sensors from the OEX recorder. I think I sort of view all these E-mails and interviews as our sensor inputs. We have a very complicated story that we are trying to fit together and ours is not a sort of mechanical story but it's very much of a human story in terms of interaction and decision-making and communications. And that part of our story on the overall safety processes, those that are written and procedurally defined, of which there are many, I think this is a very process-intense operation, a deeper question for us is how these work in reality and how communications, the various dynamics of the organization, which this part of our inquiry then flows into Group 4, not here with us today but recently constituted, headed by Dr. Logsdon, who is the director of the Space Policy Institute at George Washington University. And Admiral Gehman spoke earlier about putting our findings into context, work force patterns, budget. I think his group is entitled Organization and Policy. That's where we sort of meld into Dr. Logsdon, who will be having the lead on that issue and who is pulling together an extremely qualified group of experts who have a lot of historical context in the NASA organization.

Just to touch briefly on a couple of mundane aspects, relatively speaking, of our group's work. Training and payload issues. We're bringing those to closure. I can say we are close to completing a very thorough review of the training of the ground and flight personnel for STS 107. The records are not flawless; but they are such that, while it's not officially off the table, we've found nothing that would suggest any contribution to the accident. And the same with payloads. There's actually a fault tree on payloads that NASA will be closing out, and we're doing it in an effort in conjunction and oversight of that. Again, there were some minor irregularities with payload but nothing that would suggest a contribution to the accident.

Again, we are following and talked about this a little bit in the last press conference, about return-to-flight issues. There's the effort going on in the program level, there's an effort now directed from NASA headquarters with Astronaut Jim Halsell melding these two together, and the board will also be, in its recommendations, working on some return-to-flight issues. I would emphasize that we're all largely, I think, along the same lines; and there isn't a contest here. We all want to get back to flight. So that's the Group 2 update.

ADM. GEHMAN: Thank you very much.

General Barry.

GEN. BARRY: Sure. Good afternoon. I've got a couple of updates. First of all, Admiral Steve Turcotte, another member of our board, is at Langley today. General Duane Deal is here at JSC with me for the week. We've got a couple of trips with our subgroup members who are going to KSC and Marshall. So we're going to spread out again.

Let me give you a couple of updates. Maintenance, management and human factors, and then materials and structures. Let me just briefly mention on the maintenance side.

This Friday the board will receive a briefing that will close out, provided we approve it, the SSME as one of the fault trees, followed by, shortly, the SRB and the RSRM next week. So we're getting a full briefing, and we've been involved and engaged all along. So we'll be taking that.

ADM. GEHMAN: John, maybe you better spell out those abbreviations.

GEN. BARRY: The SSME is the space shuttle main engine; of course, the RSRM is the replaceable solid rocket motor; and then the solid rocket booster.

The other point I want to make is on management human factors. We've been engaged with numerous interviews, examining the Palmdale move and the Huntington Beach engineer move. So there's been a lot of work being done on that by our group.

The main thing I want to talk to you is to give you an update on foam, RCC ageing, and the Day 2 debris that we've got some updates on.

If I could ask for the first slide.

General Deal has been leading the charge on the foam for our efforts. We've got Lieutenant Colonel Larry Butkus from the Air Force Academy who's been helping also, as has Clare Paul. What I want to do is concentrate and focus your eyes on our dissection that we've got on the Y pod. We've also started cutting into the left side. So this is the right side, plus Y, minus Y, and I'll give you some information here.

Next slide. All right. Again, the big picture. I want to focus here. This is where it's located on the external tank, as indicated in red up here. A lot of different kinds of foams on the external tank, but we'll be focusing on this area.

Next slide. All right. I just wanted to show some of the loads that happen. This is the exact time that we've been able to record, 2.46 Mach is when the bipod foam came off on the left-hand side, allegedly. We're still trying to confirm that 100 percent. This is at the 81-second point. You can see it's a pretty dynamic engagement zone right now insofar as the aerodynamic loads.

Next slide. This will give you a color depiction. Again, there's a lot of intersecting shocks that are happening at this point for vortex pressures. You can see there's a lot more pressure from inside out here. There is no indication right now that the bipod design has not been adequate enough to accept these aerodynamic loads. However, I do want to point out that we're still examining cryopumping. So it looks like something else other than the aerodynamic loads is one that contributed to some of the losses in the past and the one we're looking at right now with STS 107.

Next slide. All right. Here is just a rehash on the previous ones we've had. This is in Challenger in '83. You can see the location of the actual paragraph and then a little bit of a schematic illustration of what they think actually happened. This was '83.

Next slide. '90. Again, the picture and then what piece we think came off.

Next. This is '92. And again, a larger piece.

Finally the one prior to Columbia. Next slide.

This was ten years later from the previous one. Last one before this was '92, and this was the piece that came off.

All right. Next slide. We are examining closely, as you know, the cryopumping issue; and what we think is there's purging that goes on in the internal part of the external tank. So inside here is purging to kind of act as a safety gas between oxygen and hydrogen. Well, some of that turns into liquid and seeps out and gets into the ablative or gets into what I'll show you here as the voids. So the cryopumping is a flash evaporation when it goes from very cold temperatures, liquid, to warmer temperatures and then turns into gas and has to find some vent there.

Next slide. Now, here is the cuts that we've been experimenting with down at Michoud. This is where I'll show you some of the photographs. This is Region 6A here, as indicated right back. We have problems with voids and de-bonding.

Next slide. You can see here we've got void and rollover. That's when the foam goes over the top as it's applied, disbonding, and then primer. We have some problems at the bonding levels.

Next slide. There are some closer photographs now here of voids that we have found in the right side pod of ET 120. That's the one we cut into. We're trying to get better at our ability to do this cutting and looking into it so when we tap into ET 94 -- that is the one that's exactly the same as ET 93 -- and ET93, as you will recall, External Tank 93 was the one that was on the STS 107.

Next slide. We've got a bigger picture here of the voids that were indicated. Again, these can capture liquid, which eventually can turn to gas when it gets warmer and then looking for a vent or a flash evaporation.

Next slide. Here's another picture of voids. Now, right now we've found about 14 voids in the right side and we're up to 18 on the left side now that we've cut into it in the last couple of days.

Next slide. All right. Now that I talked about the foam, follow the foam, this is a little bit about following the ageing. This is a pinhole on the RCC. So we have the foam come off and one of the scenarios, as you all know, is we're looking at something that hit the RCC. This was first discovered on 102-12 in 1992 and we've been examining some of the potential contributory elements that may have gone to them and we think one of the leaders is the corrosion from zinc oxide.

Next slide. Scale on the pinhole. If it is greater than .04 inches, it is out of tolerance. So this one right now is out of tolerance because of the increase in the expansion on the corrosion.

Now, this pinhole was first discovered in '92. It's on all the orbiters now, and at any given time you can look at any panel and you can count 20 to 40. The root cause of the pinholes is the paint primer that seeps down after the rain from the infrastructure that's on the pad. So the pad topcoat hasn't been refurbished and the primer gets exposed and then zinc becomes zinc oxide which then falls on the leading edge of the RCC and then we have pinholes.

Let me show you the next slide. You see the orbiter on the pad. When we have the collapse of the rest of the pad over it and expose some of the areas of that infrastructure that haven't been painted, we get the primer and get the zinc oxide. So that's one of the things that we've been contributing.

Okay. Bring down the slides, please.

All right. Day 2 debris. That's the final thing I want to bring to your attention. We do have some more information on that. As you remember, this was discovered on the sixth day after the mishap, by DOD. It was one of the most laborious reviews of radar data in history of Space Command. If you will recall, we assessed this thing when the shuttle was going on a rear vector. It turned into a right wing vector and then back to a rear. In the course of those maneuvers, we noticed that something came off; and this is what's been commonly called the debris of Day 2.

All right. Here's what we have so far on the testing. With the 3100-plus observations of Columbia by DOD, we've got a lot of radar cross-section feedback. There have been 29 various materials examined at Wright Patterson Air Force Base and we've concluded right now that only the carrier panel remains a viable candidate for the Day 2 object. Now, this radar cross-section came from Pave PAWS radar at Cape Cod, space surveillance radar at Eglin, Pave PAWS at Beale and Navy fence radar. All those combined gave us a pretty good data base on what to look for on this Day 2 debris. Then, of course, we took it to Wright Patterson Air Force research lab and put it in the sound room that we have over there and then tested it.

We think with the horse collar and the carrier panel it gives us one of the best candidates we've had so far, after reviewing all the testing, to be the leading candidate; but we still have some more testing to do. The engineer is going to do follow-on testing for four tiles versus three tiles on the carrier panel, and we also have some other looks that we want to take a look at.

Thermal blankets from the bay were also considered a possibility but because of the correct area and mass ratio when it re-entered the atmosphere, it doesn't look like that is a possible candidate. So the bottom line is the carrier panel. It looks like our best candidate so far. We do have some final refinements, and we'll continue to work that as we go forward.

ADM. GEHMAN: Thank you very much. In my opinion, it's a good week's progress; and we haven't even mentioned the OEX recorder yet.

So over to you, Roger Tetrault.

MR. TETRAULT: Right. I represent the technical committee; and, of course, we actually are the largest of the groups. We have five members; and those members include Sheila Widnall, who was at Langley yesterday, watching some of the wind tunnel testing that they're doing and getting updated on that wind tunnel testing. In addition to that, we have Jim Hallock, who is at Kennedy today; and he is reviewing the debris or looking at the debris. We also have Scott Hubbard, who is working the Southwest Research testing plan; and that plan is in a little bit of flux as of today. Also we have Dr. Doug Osheroff and, amongst other things that he's taken on, one of them is to try to come up with mechanism for chemical analysis of some of our debris to sort out at what altitudes various events happened, using Nobel gases. So that's a very tricky kind of area that he is helping us with.

As most of you are probably aware, I am the person who is responsible for both the leading edge of the wing and also the management of the debris and its analysis down at Kennedy. Today what I'd like to do is update you with four different areas; and I'm going to update you on flight data, including the OEX, and also one small item on the old telemetry data line. Then I would also like to give you a little bit of an update on the photo analysis and what's going on in that particular area, talk briefly about the orbiter aero off-nominal results and the struggle that we're having to try to come to some conclusions about the meaning of those results, and then show you one piece of the debris which is, in fact, at least answering one of the questions that we have on these off-nominal aero results.

So if we put up the first slide, this one you've seen before; but it is the OEX recorder which, as you can see, is in pretty good shape. Let me give you a kind of verbal description of what's on the recorder and what we can get out of it. It has two types of data. Data called PCM, which is pulse code modulation. This is low-frequency data and normally is used to get information about pressures, temperatures, and strain. It has FDM data, which is frequency division multiplex data, basically wide band. That data includes stress and strain sensors relative to the structural area, the vertical fin, the speed brake, and the heat shield, and also contains data relative to the main engine vibration.

The tape contains both ascent data and re-entry data, and I think most of you are probably aware that they turn on the OEX recorder 15 minutes prior to launch and it's kept on until main engine cutoff plus six minutes. On reentry, it's turned on ten minutes prior to entry interface; and the data that we have goes to the end of the tape.

Last week Scott Hubbard talked about what we could expect to find, and he told that you that there were 721 sensors that were recorded on this recorder. Of course, we're in very much a preliminary sort of stage on the information that we're receiving out of the recorder, but let me kind of put these 721 into buckets so that you have an idea of what kinds of data we're seeing.

Over the weekend there were over 100 people working at NASA to try to extract this data. They were able to extract good data from approximately 420 sensors, all on the PCM side. There were approximately 50 sensors that we don't have good data from and we don't expect to have good data from because they were not necessarily hooked up or for a variety of other reasons they were not essentially ready to take data. There was, over the weekend, 150 sensors -- and these were all strain gauge -- that were on PCM No. 3 that we were not able to read over the weekend, primarily because of a synchronization problem. They were able to read that data yesterday and we now have 150 extra pieces of sensory data, but it is all strain gauge data.

That leaves you with approximately 100 sensors. Those sensors are in the FDM, and they have not been read as of now. Most of this or a good portion of it needs to be sent to Boeing and also to California before it can be read. It can't be read here. So that gives you a pool. That accounts for 720 out of the 721 I just gave you, kind of putting them in buckets.

Let me tell you kind of in a gross-order fashion what we are finding from these sensors. We've taken a quick look at what they are telling us about ascent. That quick look on the strain gauges says that we are not seeing anything unique. Everything seems to be within family. I think Scott mentioned last week that he did not believe that we would see any foam strike at L plus 82 or something like that. We don't appear to be seeing anything that matches that L plus 82.

Let me talk about the descent. The FDM data went to Greenwich Mean Time 14, zero minutes, and 19.4 seconds. That's 15 seconds after any of the other sensory data that we previously had received. By that I mean the 32-second piece that we had that you may recall had a 5 seconds, 25 seconds missing, and then 2 final seconds. So we've got 15 seconds more than that now. In addition, we have sensors that now tell us about the 25 seconds which previously was missing.

The PCM data did not quite go so long. It went to Greenwich Mean Time 14, zero minutes, 13.4 seconds, or 9 seconds longer than the previous one. What all this suggests, of course, is that the OEX recorder, which is inside the fuselage, was receiving power during that entire period of time; and, of course, at that point the fuselage had probably not broken up.

Let me put another slide up, if I could. This is a very preliminary slide. It's under revision, but what I wanted to show you is I wanted to talk about four sensors and give you some information about four sensors. One is going to be on the OMS pod, which is not shown here. This is the lower portion of the left wing. The three that I want to talk about are all going to be in this area. One sensor is not shown. It is a strain sensor, and these are two temperature sensors.

This is 9910 and 9895. 9910 is in front of the spar. 9895 is behind the spar. Now, let me talk about these sensors and how they affect the beginning of the time line for events that we've seen before.

The first one I want to talk about is not shown on here. It is Sensor G9921, and it is right in this area behind the spar, at approximately RCC Panel No. 9. As I said, it is a strain gauge. It starts to increase and goes off nominal at Greenwich Mean Time 13:48:39. That's EI plus 270 seconds; and I'm going to try to give you, where I can, both the Greenwich Mean Time and the entry interface plus seconds after entry interface, because that's how these gauges are measured.

As I said, it's located behind RCC Panel No. 9; and it did go off nominal at 270 seconds. That's 206 seconds earlier than the first event on our previous time line. And the first event, you may recall, on the previous time line was the start of the delta yaw which was at EI plus 476 seconds.

The second one that I want to talk about is Sensor 9910, which is the one in front of the spar. It is actually attached to the clevis. I believe it is the clevis which is the outboard attachment for the RCC Panel No. 9 and where it mates with T Seal No. 10. So it's on the outboard side of RCC No. 9, forward of the spar. That one went off nominal at 13:48:59. That's at EI plus 290 seconds. It went off signal low at EI 492 seconds or approximately 52 minutes and 19 seconds. When it went off signal low, it had read only about 50 degrees, which probably suggested that the wire had been cut; and that is not particularly surprising when you recognize that this sensor actually has insulation which is packed around it, which are referred to as earmuffs.

Let me talk about the third sensor, and I'm giving you these in order. These are the four sensors in order as they went off on this OEX recorder. The third sensor is Temperature Sensor 9220. It is located on the OMS pod TPS surface and on the leading side of the OMS pod. It starts to go off temperature and it goes low off temperature at 13:49:53 Greenwich Mean Time, which is entry interface plus 344 seconds. It goes off low until approximately 540 seconds, and then it makes a rapid switch and goes high. And it actually goes as high as 1200 degrees.

Normal for that portion of the flight would expect to be around 600. So what can you gather from that? First we think that there is a change in the mass flow which moves the mass flow probably below the OMS pod and then there is something else which happens that raised the temperature rapidly up, which may be burning or burning aluminum or a number of other effects that we have to go look at.

The fourth sensor is 9895. This is the one behind the spar at RCC Panel No. 9. This one right here. And it's pretty much in the middle of the wing surface in terms of where it's positioned. It goes off nominal at 13:51:14, or EI plus 425 seconds. It goes off scale low at EI plus 520. So the wire is cut at approximately 520 seconds.

This particular one behind the spar goes up to approximately 450 degrees where it peaks and then goes off scale low. This is 63 seconds before the old time line Temperature D sensor, which was the first sensor in the old time line that was a temperature sensor. And if I go back and look at Event No. 2 which I gave you, which was the one in front of it, that was 188 seconds before brake line Temperature Sensor D first showed an off-nominal.

Now, what I would like to mention to you is it's probably even more of a delta than that because we are finding that brake line Temperature D, which established the first sensor previously, is probably not off nominal at the time that's on the time line. It's probably later than that. That's an important point strictly because Sensor D goes off first and it is in the aft of the wheel well and it is high in the wheel well, which tends to indicate that the heat is coming from the aft part of the wheel well, moving forward. But if you really look at it and say what's going on and that moves, it is much more likely that the heat is coming from the forward side of the wheel well going aft and this study that they've done that indicates Temperature Sensor D is probably nominal for a much longer period of time than they specified helps in making that case that this all begins to line up a little bit better than it had previously. In that study which NASA ran, they found that at least 13 flights had had bit flips before EI plus 500, and 11 of them had been before this flight showed the same kind of change.

Okay. Let me kind of give a general summary of the data that we're seeing. This is very general and very early, just as giving you some information about some of these individual sensors are, without a lot of review. In general, there are about 15 sensors in the left wing; and they all seem to go off scale low about Greenwich Mean Time 13:22:54, which is west of California. NASA has also looked at 17 sensors, all on the left wing, and has indicated that they believe they see a warming trend compared to previous flights with similar inclinations, and that warming trend -- not off-nominal trend, just a general warming trend -- occurs at EI plus 80. Very early in this flight.

Let me have the next slide, please. Scott showed you this slide last week, and what I wanted to do is update you on some photo analysis which has been done. NIMA, which is the National Imaging and Mapping Agency, has taken all of the photos that we had and digitized them at 50 megabytes per frame. Having done that, we have been able to actually come to some conclusions, and let me say what those conclusions are.


MR. TETRAULT: Yes, sir.

ADM. GEHMAN: We have to hurry up.


ADM. GEHMAN: Fifteen minutes has already gone by.

MR. TETRAULT: I apologize.

REPORTERS: We're happy.

MR. TETRAULT: The important issue here is the debris size, which has now been calculated to be 24, plus or minus 3; 15, plus or minus 3, and 5, plus or minus 1 -- which equates to approximately a 2-pound piece. The 24 and the 15 are measured; the 5 is a calculated value based upon the trajectory that it flew and the mass that it would have had to fly that trajectory and wind up with a velocity of 640 feet per second at the end, which is the average of the measured values that they have that it hit the wing.

There is no evidence of more than one strike. The impact point as you see it here is between RCC Panels No. 5 and 7; and no debris is seen over the top of the wing. And that photo that we previously showed you with before and after debris strike, with 16 frames and 17 frames and showing no damage to the acreage tile is now done at 30 frames and we still see no damage to the acreage tile. So this portion of the likely area that hit is a little bit suspect.

Okay. Let me just go quickly here. Next slide. This is the anomalous aero moment that we're looking at and are struggling with. The one that I like to call your attention to -- and this chart, by the way, was put together by Sheila Widnall to try to get the trajectory matching the aero that we've seen -- this represents loss of lift in the left wing and then additional lift in the left wing, which we have not been able to explain. So trying to explain what's going on here has been difficult.

If you were at the public hearings, NASA showed some wind tunnel tests that indicated, if the door was open and the ear was down, that it could happen. Other things that had been postulated are aluminum burning, missing bottoms to the RCC, a jet flow out of the wheel well, and some kind of flow on the tail.

Let me go to the next slide. I just want to show you that, given the debris that we're looking at, one of these, which is that the left main gear had deployed early and is creating an aero moment, is not likely to be a correct theory. This is a wheel, the wheel strut that you can see in this picture; and if you look, you can see nice, shiny chromium plating that goes on that wheel strut. If the plating was eroded in actual ballistic flight after breakup, the erosion would be the same on both sides, which it isn't. What you can see is there's more chromium on this side, which is the forward surface when it's deployed. If that had been deployed, that chrome would not be there. That's the bottom line.

So it says basically that the wheel well, as other data has begun to indicate to us, the wheel well was closed, the door was there, the wheels were up, and that's not the cause of that moment that we're seeing. We're still struggling with how to get there.

That's all I have.

ADM. GEHMAN: Thank you very much. I hope you can see from the three briefers -- for example, John Barry talked about the radar reflectivity studies at Wright Patterson Air Force Base -- the only piece of debris left on the table is a carrier panel. Roger's little pork chop diagram there covers two carrier panels. You can see how much work it takes and how these things need to line up, and you can see how much evidence it takes to convince us of anything. We are very skeptical.

I apologize for interrupting Mr. Tetrault there, but he could go on all afternoon. So, with that, over to you.

LT. COL. WOODYARD: We'll turn it over for questions. We'll continue our same format and we'll start here in Houston and then we'll go to our phone bridge.

Please identify your name and your organization, as well.

A REPORTER: USA Today. So are you convinced now that it was a carrier panel that came off on Flight Day 2, because you said there was some more testing to be done and I wasn't sure if that was only to narrow down the number of tiles that came off the panel or if you had other objects to rule out?

GEN. BARRY: We've exhausted all the testing on the parts that were given. There were 22 external and internal shuttle components tested at Wright Patterson, and all of them were eliminated except for the carrier panel as the leading candidate. As I mentioned earlier, there might have been some of that with the blanket, but when you compare the results of the area, the mass area ratio and the burn as it re-entered, it didn't make any sense. So right now the carrier panel is the leading indicator of all of the 29 candidate shuttle components that we provided at Wright Patterson and the Air Force research lab.

ADM. GEHMAN: But that does not equate to we're being convinced that it is the carrier panel. As a matter of fact, we were meeting earlier today; and we came up with a couple of other things we would like to have tested.

MR. TETRAULT: In addition, the testing that's going to go on at Southwest Research should help us really narrow down what items are weak in this entire system and where a breach may have occurred and help either deny or confirm this piece of data.

A REPORTER: Houston Chronicle. For General Barry. Can you just go over again the major components in this area that were tested? I think Admiral Gehman just mentioned there's a couple of more things you would like to test. Can you tell us what those are, please?

GEN. BARRY: The bottom line is that we tested, including the different kinds of tiles, the fibrous materials, the beta cloth, the insulation blankets, the carrier panel that we talked about with the horse collar, the RCC edge and earmuff seal, different variants of those, all totaling to about 22 components. We had 29 to select from, but those were the ones that we looked at for that part of the test. The eliminated majority of the components is either unknown objects either due to low or too-low RCS signatures, radar cross-section signatures. The possible candidates still stood out, and we want to look at the carrier panel now with not only three tiles but also four tiles.

If you take the carrier panel and you include the horse collar, it's a very strong candidate, matches up with the radar cross-section. If you take the carrier panel without the horse collar but increase it to four tiles, that also gives you a pretty good indication, we surmise. We've got that one added test to go through. In any case, the others have been pretty much eliminated for the reasons that I have stated.

A REPORTER: New York Times. Is the foam that's being shot at tile being tested with and without ice, or are we just looking at foam?

MR. TETRAULT: The testing right now is probably going to be delayed about a week. As I said, it was in flux; and the reason for that is this new photo information which tends to indicate a piece that's larger than what we previously had been looking at. So now the debate is what size do we actually shoot. As I mentioned to you, the thickness dimension was 5 inches. That was calculated on the mass that it would take to fly the trajectory that it would take. So if there was ice in there -- this was calculated on based on this being strictly foam. If there was ice in there which would have added to the mass, then you would have to subtract from it the 5-inch dimension to be equivalent. So to the extent that there is weight, it takes that into account already by having that 5-inch dimension.

A REPORTER: Associated Press. For General Barry. I wanted to talk a little bit about the zinc oxide contamination. Was NASA aware of this? Were they taking any steps to work around this? And just how damaging, in your opinion, is an RCC tile that got 20 to 40 pinholes?

GEN. BARRY: As you know, we've been examining the issue of ageing and looking at candidates for pinholes to explain them. Zinc oxide, that can come from primer as the infrastructure ages and doesn't get painted again, with the added rain, particularly when the orbiter is on the pad and ready for launch. This seems to be the leading candidate right now. There are other explanations, something to do with oxidation and so forth. We wanted to just kind of focus on this one. This does seem to be, from the experts' standpoint, the leading candidate. So we've taken that. We are doing some more study. We want to examine all of the issues in the pinholes as close as we possibly can to try to get to the bottom of the question -- the question being, if something hit the RCC and it was an aged RCC with pinholes or oxidation underneath that, would that be a contributing aspect to this mishap. If it hit a brand-new RCC, could it withstand it? That's why this testing they're going to do with the foam will be instructive, because we're not only going to send it against tile but we're going to send it against RCC. Roger, can talk a little more about that.

A REPORTER: I was just wondering. Were you aware of NASA having concern about this ageing?

GEN. BARRY: Yes. They had looked at this as a possible contender, and this is one of those things they have been working on for the pinhole explanations. Remember, pinholes that are less than .04 inches were greeted as okay. And they just went about either refurbishment and it was out of tolerance or they went on a repair, as Steve Turcotte mentioned last week -- as he's our leading guy on the RCC, he and his team. So they've gone through and listed all of the different RCCs that have been either refurbished or repaired, and I can give you that data again if you want it.

A REPORTER: ABC News. Mr. Wallace, you mentioned that you think we're not really quite keeping the E-mails in perspective. Would you care to put them in perspective for us, sir?

MR. WALLACE: I think I would just say again that they are part of a very complicated story and you haven't seen the rest of the story. A lot of it is developed in the context of interviews where they are strictly privileged; and this being a safety investigation where our sole objective is to determine the probable cause and look for ways to raise the level of safety, we grant these witnesses privilege, which means that their identity and what they say is protected, yet we use that information to form a part of the entire story.

Of course, we have done extensive review of material, much of which will be available to you as well, things like records of meetings from NASA and actually listening to tape recordings of meetings and comparing them with the written records and trying to sense the whole dynamic. So sort of a brush stroke by brush stroke, it gives you a picture which we have not completed; but I would just say that you don't get a balanced picture or a complete picture by any means by seeing the E-mails.

A REPORTER: Orlando Sentinel for Mr. Tetrault. Can you give us a sense of where the analysis of the OEX recorder data will go from here on, what kinds of questions and what kinds of data will be addressed?

MR. TETRAULT: Well, the kinds of data is just going to be temperatures, pressures, strains, some vibration, those sorts of things. What it is obviously showing, though, is events that are occurring much earlier in the time line, although my general sense is that it's not showing us anything that we didn't suspect that it was going to show us. It will show us, I think the one thing that I see, is that when we start looking at where the lines were cut, the electrical lines were cut, part of them were cut around 540 seconds after EI, that it will begin to help localize where in the front edge the problem is. Up until now, if I took collectively all the data that we had, I could in my mind locate this event somewhere between RCC Panel No. 5 and No. 12. I think this will help shrink that down to some much narrower one. Then when you begin to put that where the photos are showing where the foam hit, then I think you can start making some assessments of what are the probabilities of that being an initiating event, if you will. I wouldn't say necessarily the cause, but there may be an initiating event that leads to a whole series of other things that lines up with the accident.

ADM. GEHMAN: Roger, if I don't have this exactly right, I believe that, in answering this question, that this data is being looked at by literally hundreds of engineers from different disciplines and I believe that what will happen is that we will put out revisions, more revisions to the time line. We're up to Revision 15 already. I think that periodically as this data is analyzed to a degree with the engineers confident what they're looking at, we will continue to put out Revision 16, then Revision 17 and Revision 18. As you may be aware, when we put those revisions out, we annotate what's new on it. That's my understanding.

MR. TETRAULT: That's exactly correct. In fact, there is a preliminary time line that has some of these sensors already on it, but that's what they're working on and some of this data they only received yesterday and some of it they still don't have. But in looking at it, there's a lot of information on strain and stress that isn't going to show you a lot.

ADM. GEHMAN: Keep in mind that Revision No. 15 is dated like six weeks after the accident. A lot of work.

A REPORTER: NBC. For the chairman. I would like to ask about the air search issue. Those of us who are covering the story were shocked and horrified by the crash. Our condolences to the team and the people involved in the crash. I'm interested in the other air search that was work going on with the Army compass sensor that has apparently now been withdrawn. Can you describe to me how helpful that sensor was to your location and whether you intend to try and get it back to do any searches out west?

ADM. GEHMAN: We are receiving a brief tomorrow from the chief of the debris collection team. So I will have to defer any answer specifically to platform by platform just because I just don't happen to currently know it. I will say, however, that the debris search continues with the same vigor as it has been. We've got between 4500 and 5500 people every single day still picking up debris, and it continues to be enormously important. Obviously this OEX recorder is a piece of debris. I mean, that's how it was found; and it was found by somebody walking along, 6 feet away from the person beside them, and it was found in an area which had previously been gone over. So it just emphasizes how important this is.

So we are going to receive a brief tomorrow on the status, and the purpose of the brief is the beginning of the process of trying to determine how to terminate the debris search. We still have several weeks to go before we do that, but we are starting to talk about it. Air searches have been very important, particularly for the larger pieces in the wide-open area. Also, as we complete the debris searches in the areas where most of the debris is, which is essentially in East Texas, we now have to ask ourselves what do we want to do in the areas where there is less probability of finding debris but the debris that you're going to find is more important. Obviously walking side by side, 5 feet apart through West Texas is a different story when there's not much debris out there. So we don't know the answer.

A REPORTER: News 24 Houston. Admiral, at the media bridge yesterday on the information you're giving on the OEX recorder, a question was asked of you whether or not the debris that you collected represents any part of RCC Panel No. 9. Did you find that out?


MR. TETRAULT: The question was does any part --

ADM. GEHMAN: In other words, do we have any debris from RCC No. 9 or the attachment points?

MR. TETRAULT: RCC No. 9. Let me take just a second.

ADM. GEHMAN: I took that down and we passed it on to our folks and we're digging. I also by the way --

MR. TETRAULT: There is nothing on RCC No. 9.

ADM. GEHMAN: We have nothing on RCC No. 9.

MR. TETRAULT: Let me just give you one other piece of information if you would have asked this -- which if I were sitting out there, I would. What carrier panels do we have and what carrier panels are missing from the lower edge? We have pieces from carrier panels on Area 5, 6 -- I'm sorry, this is the missing ones -- from 5, 6, 8, 9, and 12.

ADM. GEHMAN: Missing.

MR. TETRAULT: Missing.

We have pieces from 1, 2, 3, 4, 7, 10, 11, and 13 and 14.

A REPORTER: NBC News. General Barry, could you provide just a little bit more detail on the process through which the pinholes were created on the RCC? It's a chemical reaction created by this interface with the paint?

GEN. BARRY: It is; and let me just give you a couple of other data points, if I may. The root cause of the pinholes in the RCC, of course, is not generally agreed upon; but the leading candidate we've got right now, as I said, is zinc oxide. The other possible contenders were salt spray from the ocean and a TEOS application providing oxygen sourcing.

TEOS is an application that's applied to the RCC in its development. What you do is you have this oxidation element that goes on that makes these pinholes and then, of course, if they get too large, they get refurbished. I do want to give you this detail, if I may; and it was highlighted last week a little bit. There have been 11 panels and 12 seals on the left side that have been refurbished, and then there have been repairs on 7 panels and 6 seals on the left side. Let me just give you an idea of what happens when we do the refurbishment, and then I'll talk about the repair real quickly.

If you're going to do a refurbishment on the RCC, first of all, you inspect the part, you disassemble it, you put a Type A sealant on it, you clean it, you repair the pinholes, you heat-treat the part to 1800 degrees, you apply the TEOS, and then you apply a second Type A sealant. That's refurbishment. And by the way, refurbishment has to be sent back to the vendor in Dallas. If you repair it, as I have listed the numbers here, what you do is you clean down the damaged area, you only apply a Type A sealant, you heat-cure it, and then you verify the contour is flush and send it on its way. So what we've been able to do is track the numbers of them; and as I said, per RCC, there were anywhere from 20 to 40 in them as they have aged over the years. And then we either refurbish it or repair it, depending on how large the pinhole is.

LT. COL. WOODYARD: Any other questions from here? If not, we'll move to the phone bridge.

A REPORTER: NBC. We'd like to go back to the carrier panel. It is now a likely suspect for the mystery piece you discovered the day after the Columbia reached its place in space. When it was going up and the impact took place, was the Columbia locked in its cradle right after that wind shear? Did that cause something there possibly to spring loose that carrier panel, or could it have come from the Palmdale modifications in '99 or even from wear of age? What's your best guess?

GEN. BARRY: Well, there's a series of incidents here that we're looking into. Let me start with the Palmdale OMM. They did do the normal depo level work on the orbiter in 1999. As you recall, it flew one more time at STS 113 and then, of course, STS 107. After the OMM, they, of course, removed all the RCC panels, put them back on, and then they found with a step-and-gap test, you know, to see if they were all flush and the right distances between them, that it was not lining up. They had to take them all off again. Then they got some of the old heads that had done this before and reinstituted and put it back in the right order. So there was some concern on our part about whether that was done right. All indications are that it has been done right.

The second thing is when the RCC follow-on flow to see what was done with any kind of changes. We know it was up near the leading edge of the No. 1 RCC that some work was done in the flow between STS 113 and 107. So what we're seeing is a series of things. We're trying to examine if any of them had factors. It's a long story, and it's still going to take a lot of investigation to be able to go through each and every one of them, from the paper review to the quality assurance review as well as the interviews that we've been able to do with some of the folks.

ADM. GEHMAN: The second part of the question was whether or not Q-loading or wind shear or anything like that on ascent could have contributed and what was the timing of it.

GEN. BARRY: As you remember, I brought up an issue where we had some what they call I-load preparation at 62 seconds. There was an out-of-experience movement of the solid rocket motor that put the orbiter in position where it was supposed to be countering a wind shear. We've looked into that pretty thoroughly right now. I'm not fully convinced yet. We've got another briefing this Friday coming in from NASA integration here at JSC, but all indications are that this was well within tolerance, certainly for the solid rocket motor to move, but also this being at 62 seconds, 61 seconds, that's about max dynamic pressure, pretty close to it. So we've still got some concerns about it, but we do have a briefing coming in Friday and we should be able to nail that one shut as either a contributor or maybe one more piece of the story.

A REPORTER: Newsday. There was a mention of 11 flights previously where there were bit flips prior to entry interface, and I'm just wondering what conclusions you draw from that.

MR. TETRAULT: When I mentioned that, I was referring to left main landing gear brake Temperature D, which is the first one that went off or went off nominal in the prior time line. The conclusion that NASA had was that that temperature sensor may not be off nominal and that the time line may need to be corrected as a result of that.

ADM. GEHMAN: And that we had seen this before.

MR. TETRAULT: I say may. They have not made the decision that that's correct, but they had found that 11 flights prior to that flight had had that same kind of impacts prior to the same time that this flight did.

A REPORTER: Aviation Week. For Admiral Gehman. You mentioned that underneath the context factors. I wonder if you could talk a little bit more about the methodology you're going to use as you get at those and how you're going to try to drive out such activity and things like the psychology of continued success.

ADM. GEHMAN: We're going to approach it from two angles. Group 4 has put together a panel of people who have written on, commented on, and studied manned space flight for ever since the beginning of it. They are going to put down some macro-level thoughts -- that is, thoughts of previous studies. NASA's always being studied by somebody, and manned space flight is always under review. So there's a rich treasure trove of studies and data and views. They are going to collect those, as well as their own. They're going to take source material like not only budgets -- I'll just give you a little example here.

Take budgets, for example. There are budgets and then there budgets. There is the budget which is appropriated by Congress that NASA uses to spend on the space shuttle, but you can go to another level of degree on budgets. You can compare what the space shuttle program asked for with what NASA submitted with what the administration submitted after OMB marked it up with what the appropriation committees finally gave them.

And there's actually a trend in there or there may be a trend in there. For example, you can find trends where the space shuttle program office asked for a lot of money and was not supported by somebody, any one of those categories. You can find trends where the administration asked for money and Congress didn't give to it them or you can find trends where Congress felt that NASA was underfunding the space program and Congress gave them more money than they asked for. There's all kinds of trends in there.

So Group 4 is going to take a kind of top-down look to see what history teaches us, to see what the previous studies teach us, to see what NASA and the administration have been told or were warned about. Meanwhile, my colleagues here are approaching the same question from the bottom up. As they do their inquiries, they are coming across habits and traits and events that they have looked at in the STS 107 investigation; and then we will intersect the two. Either their work will suggest to Group No. 4 an area that they ought to look at -- like I think the normalization of deviation was one of them that we mentioned -- or else, as the Group 4 reports out to the board as a whole on what they've found, we will find specific evidences that either confirm or deny their theories.

For example, if they say that there's been a migration of some work force trend -- this is popularly written on about changes in the NASA work force -- and they therefore find that the work force has done this, that, and the other thing, the work that people, my colleagues on the left will do, will either confirm or deny that. Then we weave that into our report. I hope that answers your question.

A REPORTER: I would like you to clarify a couple of things for me. You said that on the RCC panels there's a tolerance level of 40 thousands of an inch for a pinhole. Does that mean below 40 thousandths of an inch, it will not be repaired or refurbished and, above, it will? Second, you said that there were 20 to 40 pinholes per panel. Is that over time or is that at any given moment you could pull an RCC panel and see that many holes and would those all be repaired or would those be passed on if they're below a certain threshold? And I was wondering, finally, do you have to resolve the issue of whether the breach occurred in a carrier panel or an RCC panel. Is that a major development or conclusion that's still facing the investigation? Thank you.

GEN. BARRY: First answer to the question. If it's less than .04, that's correct. It's a visual test and kind of a press on the area to see if there's any voids underneath it, the way NASA's been operating to date. We do and are encouraging them to take some hard looks at NDE on RCC panels so you can get a better look at what exactly that pinhole has underneath it; but right now if it's less than .04, yes, it does past the test.

The 20 to 40 is over time. This is not per panel per sortie or per launch. So over the period of time, as I said, the flight the first time it was noticed it was in '92.

ADM. GEHMAN: But it does mean that on average over a long period of time there have been 20 to 40 pinholes either refurbished or repaired to each RCC panel, which tends to accumulate. Obviously what we're studying is whether or not -- we're studying the effects of ageing is what we're studying. We're not suggesting that RCC panel disintegrated and fell off the orbiter.

GEN. BARRY: But we are concerned about oxidation. As the Admiral explained a couple of press conferences ago, it's like termites, you know, underneath, digging holes. If we want to know what's underneath those pinholes, then the only way you're probably going to do is that certainly getting a little better discipline on the RCC non-destructive evaluations or examinations.

The final comment you had was the breach in the carrier panel. Yes, it is definitely one of the scenarios that is being looked at. We have about ten that we're looking at for the main landing gear and as Roger kind of commented on a little bit in his analysis, but also from the RCC or the carrier panel but certainly that is one of the theories that we're trying to go down and track down and nail shut.

MR. TETRAULT: Let me comment on the last one, if I could. We seem to have narrowed this down pretty well to the leading edge of the wing. In that leading edge, there are a number of items that could fail that could cause the accident. My list of those items includes the RCC panel, the T seal, the stainless steel structure which supports the RCC panels, the bolts that support all of those, and the carrier panel. So we have to sort our way through all of those and make a determination of which one is the real failure mode. If we fail to do that properly and we get the wrong one, then we could have a future accident. So we've got to bring it at least that far.

ADM. GEHMAN: Or else our recommendations would be so broad and general and not specific enough that they won't help the return-to-flight decision. And we would not be happy with that.

A REPORTER: CBS News. Just to follow up on that, for either Admiral Gehman or Roger Tetrault. Do your failure scenarios, if you have a missing carrier panel either with or without the horse collar, is the missing carrier panel by itself enough to generate the heat that you see in that sensor on the front of the wing spar behind RCC 9? Do you need any associated damage to the RCC to make that happen, I guess is what I'm wondering. Finally just as an interpretive question, if you guys are seeing something that looks pretty good right now that's an RCC panel, perhaps it came off on Day 2, why shouldn't I consider that the point where this breach occurred? I mean, that seems pretty straightforward to me, assuming that your continued testing pins that down.

MR. TETRAULT: The last item, I'd say your logic could lead to someone's death; but, you know, you can't rule out all these without specifically knowing and make this leap of faith that something that you know happened between Panels 5 and 12 actually happened in this particular area. You just can't make that leap of faith.

With regard to the size of the hole, without running a thermal analysis, I can't answer it specifically, but I would say I would tend to think that it would be more than plausible that that size of the RCC panel could cause all of these issues. We do know that the thermal analysis when it was done down at Panel No. 6, which started with a 6-inch hole, tended to indicate that the heat could get back into the wheel well and so on and actually support an accident. I did a quick check on the square area of an RCC panel at Position No. 6 before I came here, and it was about 92 inches. So given the heat, the thermal stuff that I saw based on 6 inches, I would say it's pretty well assured that 92 square inches could give us the kinds of conditions that we're seeing here. I'm saying that with some degree of confidence, not having run a thermal analysis.

ADM. GEHMAN: That's right. We have to caveat that by reminding everybody of my introduction in which the thermal story has to line up with the aerodynamic story which has to line up with the time line reconstruction story. So if you assume that you have a breach of some sort in the vicinity of RCC No. 6, either a carrier panel or a broken piece of RCC or something like that and then your closest temperature sensor is in the vicinity of RCC Panel No. 9, you have to calculate whether or not the heat can get over there and how does the heat get over there and how would the sensor react. Then you have to find out what the aerodynamic forces are. So you're way ahead of us. We would in no way conclude that we found the initiating event here.

A REPORTER: Earth News. For General Barry. With what you showed with your hand motion of the maneuver of the shuttle on Flight Day 2, was that at 23 hours after launch, the inertial measurement maneuver, or was it some other time and, if so, do you have that time? All I've heard for re-entry was four days later over the Pacific Ocean. The Pacific Ocean's fairly large. Can you narrow that down a bit or at least give me a time for when it re-entered and whatever the mystery object is? Any idea of what the orientation was, especially if it was a carrier panel? Was it edge on, slip stream, or sideways or what?

GEN. BARRY: We'll have to get back to you on the exact time. It was on the second day. I just don't know the exact location. My understanding was the velocity vector was going backwards. You know, they did about 250 maneuvers on these 16 days as part of their experiments. So the orbiter was changing many, many times. On this particular case, it was going on a rearward velocity vector. It did turn into a right wing going downstream and then came back to having a rearward velocity vector. In the course of that time -- and I don't know exactly where it was located -- we can get that for you -- that is when we saw this piece come off, and we're relatively confident now that it did come off the orbiter. It wasn't something that showed up somewhere as a meteorite or something like that. The velocity vector that it had coming off there did lead us to believe that it did come off the orbiter.

Things have come off in the past, as you know. We've seen blankets when the doors have opened, and astronauts have told us that screws and different things that have been debris in the inside of the payload bay have come out. So this is not unusual. But the size of this -- and certainly to be tracked. Now, remember this was not picked up by any DOD sensors until six days -- really we started looking right after the mishap, but it was a combination of all of the looks from all those radars that I mentioned to you and by the sixth day we concluded that we did see something there and then we tracked it through to when it burned up in the atmosphere.

ADM. GEHMAN: Let me follow on John's answer there. John said we saw it come off the orbiter. We did not see it come off the orbiter. The first radar observation of something on orbit, accompanying the orbiter, as I recollect, was an hour after the last of these yaw maneuvers. So the orbiter was back flying stern first and the DOD system just happened to look at the orbiter about an hour after that and there it was. So it would be wrong to characterize that we saw it come off the orbiter.

The second -- part of the question was the object is tumbling. Is that correct? The object is turning in space? It doesn't have an edge attitude or anything like that?

GEN. BARRY: Initially it doesn't show a lot of tumbling. Of course, as it re-enters the atmosphere, it starts going into more tumbling. Sheila Widnall has been looking into that as something else that we can combine with Lewis Labs and be able to get some more information. So there's still some more work to do.

ADM. GEHMAN: We can calculate the mass and shape of it.

A REPORTER: New York Times. Could you tell me, please, do you have a candidate mechanism in mind for how on earth you get a debris strike near max Q on liftoff, you damage the carrier panel either on the upper side of the wing or the lower side of it -- I don't know if you can say which -- and it survives all the way into orbit and is gently shaken loose by the motion of the shuttle yawing?

ADM. GEHMAN: Well, the answer is, no, we don't. But part of our testing at Southwest Research will be to characterize debris strikes different than the body of knowledge about debris strikes in the past, to see whether or not these debris strikes can create the kind of debris that the panel here has been talking about, including a carrier panel.

As far as the second part of your question, all of us have spoken to astronauts who on their mission have looked out in space and seen some part of the shuttle, which has been attached by nuts and bolts and screws, go drifting by. So, you know, these thermal blankets in the payload bay, they're all held on with clips and they've got wires. They're not supposed to come off either. One of the astronauts told me he looked out the window on Day 2 and saw a washer go by.

So, no, I don't think we're going to be able to prove that something came off, but I know we'll be able to get plenty of testimony of instances in which things which were firmly attached to the orbiter at one time came unattached later on. So that's the best I can do for answering that question.

GEN. BARRY: The only thing I might add is, you know, we did have a negative angle on attack on launch for a brief period of time. Then it goes to positive; but the higher you go, the less dynamic pressure you have. Of course, the less dynamic pressure you have, you know, maybe there is some issues there where there can be less chance for things to come off. We haven't quite figured that out, but certainly with the testimony we've gotten, as the Admiral has said, and the indications that we've had from certainly the radar cross-section, you can't rule out the aspect of something coming off the orbiter. We've still got some more work to do.

ADM. GEHMAN: One of the more common events are blocks of ice coming off the orbiter. Occasionally big blocks of ice which are attached to dump nozzles or exhaust nozzles -- and they're really attached pretty hard, I guess -- will just detach themselves and float away.

You might mention ice as a radar reflection candidate.

GEN. BARRY: We did. We looked at it, and it didn't meet the test.

ADM. GEHMAN: Ice is out.

A REPORTER: Discovery Channel. I'd like to know if you could please go back through three different points in time, to the time of the Boeing analysis during the shuttle flight to the data from last week and from the new analysis now and give us the dimensions of the debris, of the foam, and the probable strike zone on the orbiter and how that has changed as time has progressed.

MR. TETRAULT: I can give you what it is now. I'm not sure what was used in the analysis, so I can't make the comparison for you. Maybe one of my other friends up here knows that data off the top of their head. What we're looking at now, based on the photo analysis, is 25 by 15. These are 25, plus or minus 3, by 15, plus or minus 3, by 5. And I think that is probably larger than what they were using in the crater analysis, although I must say that what we're looking at is a strike which is not in the area where they used crater analysis to analyze.

GEN. BARRY: I'd just mention a couple of things on the crater. It is 20 years old plus, and it's a simpler algorithm than certainly we have today with hydro codes that are available. So I know NASA is looking into that as another thing that can be added to improve things. The model doesn't really account for lift because, you know, it just takes the impact velocities, the angles, and the density. Stiffness is not really in the crater program to speak of. The crater can do 3-D orientation, ballistic characteristics, and the crater analysis did not really look at the worst case with carrier panel impact or RCC as a case in point.

The one that is interesting also is the debris assessment team judged that the densified layer will remain attached to the crater even though it predicted damage exceeding tile thickness. So we're trying to not only look into the analysis that was presented for crater but also what follow-on improvements could be made based on the current technologies of today.

MR. WALLACE: I would just add two quick points, having gone through a lot of communication on crater analysis but not into the analysis in technical detail itself, is that there were several sets of dimensions. So I think there were different assumptions made. If it comes back to one specific number, we'll get that and get back to you.

LT. COL. WOODYARD: This concludes the press briefing today. Again, we thank you for coming out.

(Conference concluded at 2:23 p.m.)

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