CAIB News Conference NASA JSC 25 Feb 2003 – Part 4
DEAL: Well, again, it’s too early to speculate on that. They will be doing some tests at Wright Patterson Air Force Base, based upon the radar signature that they were able to get off of it. You could conjecture any type of scenario, anywhere from tile to–if you think about where this was in the flight profile of the Columbia, they had already been on orbit and they had opened their payload doors.
Could it have been something separated from there? Sure. You could build any kind of scenario.
So that’s why the continued analysis, based upon what they got from the signature, from the size, from the number of hits and from its orientation, will be critical for them to help eliminate that or determinate that that is a factor in this mishap.
STAFF: We’re now going to take questions from NASA Headquarters in Washington.
QUESTION: Admiral Gehman, can you tell us more about your trip to Washington tomorrow? Who invited you to come? Who will you be meeting with?
And is this a fact-finding trip for you, wanting to interview members of Congress? Or is this is a briefing trip, where you’re giving them the information?
GEHMAN: I’m going to go see half a dozen members of Congress–half a dozen members of the House and half a dozen senators who are on the oversight committees that provide oversight for NASA. And I’m going to give them an update on where we are, what we’re doing and how we’re organized and let them meet me and see me so they can put a face with a name.
And I’m also going to listen to them, to make sure that our report is comprehensive enough to satisfy their needs and their requirements. So there will be a little bit of me talking and a little bit of me listening. It certainly is not part of the investigation of the accident.
QUESTION: For Scott, what is the status of new tile foam impact physical tests? When and where and if they’re going to be done independently?
And is it fair to suggest that nothing so far has contradicted the theory that the foam impact may have done something to the tiles that may have contributed to this breach?
HUBBARD: Okay, let me address your two questions there. The first one: what is the status of testing? There have been, as you know, tests in the past by Southwest Research Institute of firing various types of shuttle foam materials at targets.
What we’re interested in is eventually some testing that may include not only, say, the tile or the reinforced carbon/carbon leading edge, but also the structure underneath it. This is part of our systems approach.
Those tests are not scheduled yet. NASA is moving out smartly in doing a whole lot of different tests. They are preparing to look at things like external tank insulation that’s been produced for, let’s say, a cousin tank, cousin external tank.
So there are a lot of things underway. Can’t give you a schedule right now. But it is our expectation that we will need this kind of test data in order to begin to conclude whether or not the external tank foam, in fact, played a major role in this tragedy.
Now that leads into the second question. And I would, I think, turn it around and say: What is there that proves that external tank foam insulation by itself can cause enough damage for something like this mishap to occur? Remember, I said that there is almost always a chain of events in accidents and complex systems.
So in looking back at the previous situations where it was observed that external tank insulation–and I’ll come back to insulation in a minute, what does that really mean?–fell off and then when the orbiter returned, there was observed damage to the tiles. Now that’s a correlation, but it may not be a cause and effect. The routine number of dings that the tiles get is somewhere over 100 from a typical flight.
In pressing down through levels of detail in observations of external tank insulation falling off and actual damage to the tiles, there is only a few cases where I think you could actually document for sure that a tile damage was correlated with a external tank insulation falling off. So I think we need to be careful about connecting every single event.
What does the external tank insulation consist of?
One of the things that our group is very interested in: is it only the lightweight foam? Is it the lightweight foam plus the material underneath, which goes by the name of SLA-561. It’s an ablative material. It’s a protecting material.
It is the same ablative material that was used for the Viking heat shield and is being used for the Mars Entry Vehicles that will be there next year. It’s been around a lot time.
And third: could there be other things in there? Could, perhaps, some piece of a cap of a heater element or something come off?
So in the spirit of looking across the board, I want to emphasize that this external tank insulation event needs to include more than just the lightweight white stuff that turns orange in the sun.
QUESTION: Two questions. One: I was wondering if you have learned anything from the piece of the left wing that was found earlier?
And two: I have heard and read that the reason there was the burst of–the loss of contact between the five seconds and the two seconds in that 32-second period is because the antenna on the shuttle wasn’t properly lined up to send signals back to Earth because it was tumbling so much. And I was wondering what you think of that idea.
GEHMAN: In the case of the first question, all of this tile debris is still being put together in kind of a jigsaw puzzle. We’re not ready to announce any findings or anything at all from what we’ve learned or from what we found.
We found some interesting things, which we have relayed to you. But we’re far too far away from coming to any conclusions or any findings.
As far as the missing 25 seconds in between the five seconds and the two seconds, I wouldn’t characterize it the way you did. As the shuttle turns and pivots, as it travels around the world, as it shifts, it has multiple antennas, radio antennas, it always tries to keep a direct line of sight between one of the TDRS satellites and its antennas.
Sometimes there are a few seconds where it’s interrupted. Sometimes, the re-entry hot gases and flow around the shuttle temporarily, for a few seconds, interrupt communications. That’s been normal.
But I wouldn’t characterize it as some antenna was pointed in the wrong direction or something like that. This is just a normal interruption of communications for a few seconds that happens every once in a while.
STAFF: Thank you. We’re going to move to questions from Langley Research Center in Virginia.
QUESTION: I have a two-part question relating to the NASA-Langley emails released last week.
What evidence do you have that supports or contests a Langley engineer’s theory that tires bursting in the left wheel well could have caused the catastrophe? And secondly, another Langley engineer speculated that the launch debris could have been ice from the external tank dump line. Have you studied that scenario?
GEHMAN: The answer to both questions is “yes.” We are entertaining all scenarios very seriously.
There are some on-orbit telemetry to suggest that the tire exploding is not very plausible. But we’re going to run it down since we have good solid telemetry of tire pressure.
But the ice business is being taken very seriously. Scott clearly alluded to that, that whatever hit the shuttle isn’t necessarily just foam. It could be a lot of things.
And oh, by the way, it’s possible that that left bipod ramp is not the only source of the foam. That has shed foam in the past. But there are other places that foam could have come from.
That foam could have been saturated with ice, which would make it very dense. All these are things we’re looking at very seriously.
STAFF: Okay. We are going to move back to questions here, probably take about four or five questions here max.
And then, what I’d like to let the TV folks know is that we’re going to have a nine-minute feed uplink of debris recovery efforts around Lufkin and Nacogdoches. Just want to let you know it’s available.
And why don’t we take a question over here?
QUESTION: Can any of you gentlemen tell us whether the areas of closeouts–that is, patches of foam applied either at the tank assembly facility or at Kennedy–is an area of special concern or study?
GEHMAN: I’ll speak in general. And this is being followed up on by the gentleman over here to the right, particularly by General Deal and his guys.
We have studied very carefully every time anyone touched the Columbia between flights. We have the records of every piece of tile that’s been repaired, replaced, minor repairs, big repairs. We have all those records.
And we are looking at them very, very carefully to see whether or not any of them are of any interest. And then, of course, if we get a piece of debris that is one of those repairs, we can put some things together.
But the answer to your question is “yes.” That’s an area of great concern to us. And the Materiel and Refurbishment Group, specifically, that’s on their list.
Duane, you want to . . .?
DEAL: Not much I can add to that, other than echo what the admiral said. We will be looking in-depth at it. That’s one of the reasons we are going to the Michoud Assembly Facility this week.
We’ll be looking at the quality assurance processes, what the inspections were, the government inspection points, in addition to the contract inspection points, what the processes are, how they inspected it through non-destructive inspection as well. And, as has already been mentioned, we have a kind of little bonus here that the sister tank to the one that was on board of Columbia, which was number 93, 94 is still in the plant and impounded. So we’ll be able to group with group three and do types of testing on that because it is in family.
STAFF: Thank you.
QUESTION: My question is for Scott Hubbard. And it, too, has to do with your opening remarks about the thermal testing that’s planned on the wheel well.
Can you elaborate a little bit on to what extent this testing is intended to tell you whether this breach occurred around the seal of the wheel well door, on the leading edge where you have the carbon composite, or somewhere on the top of the wing and how that answer, when you get it, would fit into the larger story of what happened here? Could you sort of connect those dots, please?
HUBBARD: I’ll do the best I can.
GEHMAN: Scott, let me interrupt by saying . . .
HUBBARD: Sure.
GEHMAN: First of all, it’s not testing.
HUBBARD: That was my first point.
GEHMAN: The first thing he was going to say.
HUBBARD: My first point is this is not testing. This is analysis in a computer. For decades, there has been a trade called computational fluid dynamics. And we have people out there that are very adept at taking wind tunnel data, coupling it with computer methods and then being able to use that to extrapolate what might happen in some future design.
That’s the way most modern aircraft have been done. And there was tremendous amount of this calculation done in developing the shuttle.
So what’s going to happen is they will take these computer models that they’ve got of flow of this rarefied atmosphere–I mean, we’re up at 200,000-plus feet. The atmosphere up there is 100,000 times less dense than it is here on the ground.
And they’re going to introduce into those models–those computer models–holes of breaches of various sizes and shapes in different parts of the wing. And then they’re going to look and see how the heat of that very rare, sparse atmosphere could get inside the wing and then where it might go from there.
And if you have access to the website and go in–I believe it’s available–and you look at a cross section of the wing, you will see there is all kinds of structure in there. So as that flow goes in, it gets very complicated.
And that’s why the first cut analysis was a good thing to do, which is just assume that you can get somehow–through the seal, through the door or somehow–this amount of heat in there and see if that correlates with the measured temperature rise. The first cut, it does.
Now though, you have to ask yourself the question: can you box this in? Put a breach at the front leading edge, put a breach at the wheel well door, put a breach at the seal of different sizes and shapes and then see where that takes us and see if that begins to match with the data that we’ve got.
So this analysis is ongoing. But again, it’s stuff done in a computer. It’s not testing.
GEHMAN: I’d like to follow up on that because there have been several questions on this. We actually have six of these analytical detective works going on. And the idea is that if you come up with a thermodynamic scenario, it also has to match the aerodynamic scenario, which also has to match the timeline that we have constructed as to which sensors went off.
That then has to match the debris shedding scenario. That has to match the imagery, the photographs of the debris shedding, which also has to match the evidence that we pick up from the debris on the ground.
And then we hope that we’ll be able to go back into the documentation of the repairs of whoever touched the shuttle. So there are six separate detective stories, one of which is the thermodynamic detective story.
And once we get a convergence of what appeared in the telemetry, what appeared in the photographs, a theory of how it could have happened thermodynamically, a theory of how it could have happened aerodynamically, we’ll be getting somewhere now. It won’t be proof. But it will be a convergence of possibilities.
And we have been beating up on the thermodynamic one here because it’s very interesting. But even when we get a thermodynamic scenario which matches, then it also has to match these other five that I mentioned in order for us to have any confidence.
QUESTION: Admiral, you were saying you can’t be sure exactly where the tile we saw came from. How specific can you be? Any more specific than simply saying it came from the glove area of the wing?
And you also said it did not show typical wear for tiles heat facing surface. Can you explain what’s untypical about it?
GEHMAN: First of all, we got our tiles mixed up. The tiles which came from the glove area was the tile which I don’t have a picture of here, the farther westernmost one that was found near Littlefield, Texas.
This tile, which was found in Powell, Texas, just 30 miles west of Fort Worth, the one I showed the picture of, it’s the one that has the very extreme heat damage to it. And whether that damage was caused while it was still on the shuttle or after it broke up or something like that, we have a lot of investigating to do.
We don’t know that. We don’t know that.
But this heat damage on this tile is not re-entry damage of a shuttle. It’s not what they look like when they come back.
QUESTION: Is there an easy way to say what it should look like?
GEHMAN: It should be smooth. And it should be slightly gray, very, very slightly gray, smoky and smooth. Maybe a couple little tiny pocket marks in it from the 100 hits that Mr. Hubbard referred to.
Okay.
QUESTION: I had a question about the final two seconds of data, telemetry data. Is it possible to say anything more specific about this? And by that, I mean we know the APUs were working. Can you say what other systems the telemetry data said were working on board the system, such as computers and other things?
And also, we know that they hydraulic fluid had drained out. Were there any other sensors, particularly sensors in the left wing, that had been working prior to that two-second period that were off scale low or not working in the final two seconds?
GEHMAN: Correct me if I’ve got this wrong, Scott. As far as we can tell, we have told you everything that we know that wasn’t working with one exception; and that is that in the final two seconds, there were no signals from the left wing. Is that right?
HUBBARD: I believe so.
GEHMAN: Yeah, I think that’s right.
HUBBARD: We’ve said everything that wasn’t working. There is a whole long list of things that were working.
GEHMAN: That’s right. As far as we know, in those last two seconds, the guidance system was talking to the jets, was talking to the elevons. The nose of the craft was talking to the tail. All those systems were intact.
And the big anomaly that we noticed was that the reservoirs of the hydraulics were empty. That’s the big anomaly that seems to stand out to us.
STAFF: This is the last question.
QUESTION: Gentlemen, I wonder if you have looked at the three analyses produced by Boeing during the flight. There is now a contention out there that Boeing’s analysis of the possibility of damage on liftoff was deficient because Boeing has restructured, moved personnel here, lost some of its knowledge base.
And in the fault tree, failure to make proper evaluation then led to failure to take preventive steps later, whether you have followed that or reviewed any other aspect of that analysis and whether your supervision of the NASA investigation also extends to whether the people doing that investigation have any conflict of interest, whether they are investigating what they formerly directly supervised?
GEHMAN: The answer to all your questions is “yes.” We are looking very carefully at the foam analysis from a half a dozen points of view. You’ve heard three or four of them here today.
Was it just foam? Maybe it was foam plus a blader. Was it foam plus ice?
And then all the other things that you mentioned about conflicts of interest and who did it and were they qualified and all that, all get looked at. It will all get looked at.
It’s in progress. Though I don’t have anything to tell you about it. It may have been done wonderfully. It may have been done expertly.
There has been some speculation in the press by some experts about the statistical methods, that they weren’t happy with some of the statistical methods and things like that. We’re going to look at all of that. We’re going to look at all of that.
I do apologize that I am going to have to cut it off here after an hour-and-a-half. As I say, we will be available every week so you can dialogue with us. And the public will be a week from Thursday. It will be open to the press.
And we think that we have told you everything we know. So thank you very much.
STAFF: Thank you everyone. And there will be a screen up for a few minutes that will have information about the board’s website and how to contact us.
Thank you very much.
