Transcript

STS-107 ACCIDENT RESPONSE BRIEFING
JOHNSON SPACE CENTER
1. Februar 2003

Kyle Herring, Public Affairs Officer
Ron Dittemore, Space Shuttle Program Manager
Milt Heflin, Chief Flight Director

I'd like to introduce the panel for this afternoon's briefing. On the dais here to my left is Ron Dittemore. He's the Space Shuttle Program manager. And to his left is Chief Flight Director Milt Heflin.

I'll have brief remarks from both gentlemen, and then we'll throw it open for questions.

DITTEMORE: I'm sure you understand how difficult a time this is for us right now. We're devastated because of the events that unfolded this morning. There's a certain amount of shock in our system because we have suffered the loss of seven family members, and we're learning to deal with that.

There's certainly a somber mood in our teams as we continue to try to understand the events that occurred. But our thoughts and our prayers go out to the families of Rick and Willie and David and Kalpana, Michael, Laurel and Ilan--true heroes. And we are suffering for the events that have happened this morning.

As difficult as this is for us to do, we wanted to meet with you and be as fair and open with you, given the facts as we understand them today. We will certainly be learning more as we go through the coming hours, days and weeks. We'll tell you as much as we know. We'll be as honest as we can with you. And certainly we'll try to fill in the blanks over the coming days and weeks.

As difficult a situation as this is, we are moving forward. We have established a number of different teams. We have contingency plans for just these types of events, though we never expect to use them.

We have implemented these contingency plans. We are preserving data. We are beginning thorough and complete investigations. We are mobilizing our forces, our engineers, our technicians, our safety and quality, our best experts to try and understand what went wrong.

I do want to take the time right now and express my appreciation for the tremendous number of agencies that are coming to our aid from across the country, both federal, state and local, that are assisting us in our recovery operations.

I also want to express my appreciation to the public for assisting in the recovery, for notifying us of different debris, where it is located, that we might get to is as quickly as possible.

It's also appropriate that we tell the public to be careful with the debris. What we fly in space is operated, in many cases, with toxic propellants, and some of the debris may be contaminated. So we need to be careful. And we don't wish any harm to come upon anybody that would be honestly seeking to help.

At this hour we have not positively identified any items that we have recovered. We are staging in an attempt to ensure that all recovered items are managed appropriately. But at this stage, I haven't received any real information on debris or status of crew remains.

I can go back to the start of the day, filled with excitement and anticipation. Today was a great day to land in the Florida area. We had all positive indications that it was going to be like every other day where we have landed in Florida--good weather, anxious team to welcome a fantastic crew back, families that were excited about welcoming their loved ones back, and no indications at all of any impending threats to the vehicle.

The first indications of a potential problem occurred minutes before 8 o'clock central standard time. The first indications were of the loss of sensors, temperature sensors in the hydraulic systems on the left wing. Both the left inboard and left outboard elevon temperature sensors.

They were followed seconds and minutes later by several other problems, including loss-of-tire-pressure indications on the left main gear, and then indications of excessive structural heating.

I have to caution you that we cannot yet say what caused the loss of Columbia. It's still very early in our investigation, and it's going to take us some time to work through the evidence, the analysis, and clearly understand what the cause was.

But what we are doing is we are impounding hardware so that we can preserve evidence. We have stopped processing at the Kennedy Space Center. We are preserving hardware around the country in our different facilities. We are impounding data here that represented the last data that we received from the crew. And we will be poring over that data 24 hours a day for the foreseeable future.

HEFLIN: First of all, just some personal observations and comments to begin with. Then I'll review some data with you.

This is a--this is a bad day. I'm glad that I work and live in a country where we have--when we have a bad day, we go fix it. Ron said, "We'll fix it."

I can talk to you some about what went on in the flight control room with the entry flight control team under the guidance of flight director Leroy Cain. Ron said it was a good day to land. In fact, many of us, as we came in today, were marveling at the fact that Leroy Cain did the ascent as well and probably the most difficult things that we deal with during launch attempts and entries is dealing with the weather, as you all are accustomed to.

And we marveled and felt good about the fact that, you know, launch we didn't have any weather issues to worry--in fact, any weather issues anywhere in the world that we were concerned about. And today, it was a very minor thing to talk about some fog, I believe, but nothing really hard to work.

So as Ron mentioned, this was a fantastic mission and just seemed to be coming to the right conclusion.

Just some specifics for you. And bear with me, this is relatively recent, fresh information. And as you can imagine, in the next several hours and days, this will be--we'll get closer to many details, I'm sure.

Around 7:53 a.m. Central time, as Ron mentioned, we saw indication of off-scale low temperature measurements on the left inboard and outboard hydraulic systems. This is loss of the temperature measurement. It wasn't any indication that it was high or low. We just lost it.

About three minutes later, around 7:56 a.m., in the left main gear tire wheel well brake line and tire temperatures, there we saw an increase.

Now, I need to tell you that during this time the vehicle was performing fine. We had no indications of any problem.

Around 7:58 a.m. Central time, a couple minutes later, we have what we call bond line temperatures. These are temperature sensors that are embedded in the structure of the vehicle. We have them all over the orbiter.

Three of these temperatures on, again, the left side of the vehicle, the left wing area, the off-scale low reading again. This was not high indication, low indication, but they were--we lost measurements.

Don't have the seconds here. Clearly seconds will play a part in our analysis, but I'm giving this to you at the nearest minute.

Around 7:59 then, Central time, left inboard and outboard tire temperatures and pressures, off-scale low. About eight measurements total during that time.

One of these--one of these measurements sensed on board by the computers gave the crew a message, indication that they could look at on their displays. And they--we think they were acknowledging that measurement that they saw.

And when things like this happen, when a crew gets an alert, you acknowledge it, they recognize they've seen it, and then we go and do what we might need to do with it.

And as far as I know, that was the last transmission from the crew. I've asked a couple of people, I haven't heard the tapes myself. I'm not sure what they said at the time. But they were acknowledging, we believe, that indication that they'd seen.

Then we lost all vehicle data. It looks like it was around--and I apologize, it looks like my little cheat sheet here doesn't have the last Central time on it and I'm not going to try to convert it to you at this point, but it was around 8 o'clock Central standard time. Altitude was 207,135 feet, and traveling at a mach of about 18.3.

And the flight control team, during this time--again, we lost the data, and that's when we clearly begin to know that we had a bad day.

As you can imagine, we have a lot of centers around the agency that are involved today. So we're going to try to limit the questions to one and try to get through as many as we can.

I need you guys to do me a favor and when you raise your hand, wait for a microphone and please give your name and affiliation first.

And we're going to start here in Houston and then go around to the other NASA centers. So let me see a show of hands, and then we'll try to get somebody to you.

DITTEMORE: We haven't yet identified a central location. Part of the activities that are ongoing, even at this very moment, is to stage our teams into a location in northeast Texas.

We are still identifying the locations for our teams to meet and gather and start this process of recovering debris. And part of their first activities is to identify the staging area, the collection point of all the debris. So that's some work that's going to be done later on today.

The teams are--let's see, they're not quite in the air. They're staging right now at the different airports, and they are converging on northeast Texas. And so, that's some work that's still in front of us.

QUESTION: At this point, what is the status of the shuttle program and particularly the upcoming missions you were going to have? Have you decided to put all of those missions on hold? And do you have any kind of idea of how long the program will be out of service?

DITTEMORE: Well, of course, this thing happened just this morning. And we put in motion some stop-work types of activities.

As I mentioned earlier, we've minimized our processing at the Kennedy Space Center so that we don't do anything that might disturb some evidence.

We are also slowing down our manufacturing processes in the MASHU (ph) facility in Louisiana where we manufacture the external tank. We're doing that in different areas around the country for different pieces of hardware.

We also will be having an investigative board outside the agency, as mentioned earlier by Mr. O'Keefe, that will come in and help resolve this situation to everybody's satisfaction so that we clearly understand what was the root cause of the problem.

And once we get on that path of understanding the root cause, then we'll be better able to say whether it affects future flights. If we can put it off to the side and get it narrowed down and say, "OK, we understand the root cause, here's the things we do about it or need to do about it," and then accomplish that corrective action on the other vehicle flows, then we'll be able to pick up our flight progress again.

How long that's going to take, it's too early for me to tell. But I do believe that we'll continue to meet with you and keep you informed of just how this is progressing.

I've talked to Mr. Bill Gerstenmaier, who is the program manager for the International Space Station Program.

DITTEMORE: They have scheduled a--they had a previously scheduled Progress launch tomorrow. And that Progress launch will proceed as scheduled.

They have reviewed the contents that are going to be shipped to the space station. And those contents are appropriate, given the fact that we may not be there for a while.

There--they have enough consumables, supplies for the crew to go through the later part of June without having a shuttle visit. So there's some time for us to work through this and get back on our schedule. And we're just going to have to work through that in the coming days and weeks.

But right now, there is a--certainly there is a hold on future flights until we get ourselves established and understand the root cause to this disaster.

QUESTION: And I was wondering if you could explain to people who are not from this area really how tight knit of a community this is, not just here on the NASA JSC campus, but all around here how much of an integral part of the community this is to you all.

DITTEMORE: Well, it's more than a job. This is a passion for us. Human space flight is a passion. It's an emotional event. And when we work together, we work together as family members. And we treat each other much that way. And whether it's the loss of a crew member of a loss of a member of our ground team or processing teams, it's a sad loss for us.

And so we are a very close community. We understand the risks that are involved in human space flight. And we know that these risks are manageable, but we also know that they're serious and can have deadly consequences.

And so we are bound together with the threat of disaster all the time, and we know we must count on each other to do what's right. We must count on the ground teams to process correctly. We must count on our suppliers to follow the procedures, just like we have identified to them. And we count on the flight crew members to fly the vehicles within the specifications.

So we all rely on each other to make each space flight successful. So we have a dependency, and it's a professional dependency, and it's an emotional dependency. And so, when we have an event like today where we lose seven family members, it is devastating to us.

And it's more than just us in this location. There is an emotional attachment to human space flight. It peaks our interest, it captures our imagination.

I received a couple of phone calls this morning immediately following the--when it became apparent that Columbia was no longer going to land. One phone call was from my brother in Phoenix, Arizona, not associated with the space business. I haven't talked to him yet. I just received a message certainly extending his thoughts and prayers. I received another phone call from my son in Provo, Utah, with the same emotional outpouring of sadness.

And I'm sure this is true across the country. We're seeing that from the public. We're seeing that as people that really care about the space program and understand what it means to this nation reflect their thoughts, their prayers, their caring attitude to us. And we want them to know we appreciate it very much. As we struggle with our emotions in this difficult time, we appreciate the thoughts, the prayers, the care and the support.

HEFLIN: Well, yes, it is--the community out here is extremely closeknit. I've been through three of these, and each time you see a coming together of the community here.

Our landscape has changed. The space flight business today is not going to be--it's going to be much different than it was yesterday. It was different after Apollo I; it was different after Challenger. And it was different because this community--Ron's right. The passion is here.

And as Ron was talking, I was thinking about your question, and I thought, you know, sometimes it's a shame that it takes things like this for this country to pull together and care. And it shouldn't. Man, we're good. This country is great. It shouldn't take these kind of things to cause a coming together.

QUESTION: You mentioned about eight sensors and one of those that triggered notification inside the shuttle. Can you tell us which sensor that was and whether it was an abnormal reading on whatever sensor it was or whether it just that the sensor was no longer functioning?

HEFLIN: There were in the left inboard and outboard--these are tire temperatures on the left-hand side, OK. Temps and pressures--and, Ron, help me out here if I get that mixed up. And they all went what we call off-scale low.

In other words, there's a bottom number; zero or maybe not zero, not necessarily zero, but there's a bottom number of the measurement. They all went off-scale low, indicating loss of the measurement itself.

And I cannot tell you specifically which one of the eight. We'll find that out, but I don't have that right now.

DITTEMORE: An easy way to think about that is the measurement was no longer reading. It was not giving an indication. It's as if someone just cut the wire.

QUESTION: You indicated that, at 7:53, was the first--you first lost some sensor information. And you indicated toward the end there was an acknowledgement from the crew. During the rest of that time period, there was any dialogue, any communication with the crew during that period?

QUESTION: During the rest of that time period, was there any dialogue, any communication with the crew during that period? And was--if there was, was there any indication from them that there was a problem that they could see on board?

HEFLIN: Yes, at 7:53 a.m. we did have another set of four measurements in the hydraulic system on the left-hand side that went off-scale low.

Now, this was reported by the flight controller responsible for the mechanical and hydraulic systems in the orbiter, reported to the flight director.

When this happens, then it's followed up by if there's any action to take, if there's anything that we see that needs to be done, that flight controller will tell the flight director and the crew--and a call might go to the crew.

These were measurements that did not have--we have many measurements onboard. Not all of them are enunciated to the crew. They don't need to be. We see a lot more information on the ground than they do. So they did not see this. So they had no indication.

We saw nothing else to indicate any difficulty at all, because had we seen anything else, we would have taken some action. That's--you know, we work, we work very hard. We train very hard to react in a very short amount of time to situations. But we don't--if we don't have anything that we see that we've got to do, then we don't spend the time talking about it because we focus on the next event and so forth.

QUESTION: We had heard some reports that during launch there had been some concerns that some debris hit the wing. Is that true? And is that any cause of concern that that could have caused today's problems?

DITTEMORE: It is true that right after launch--and I don't remember the time frame as far as the seconds--there was a piece of foam that is used as insulation on the external tank in the area of what we call the bipod, which is the forward attach between the orbiter and the external tank. There is a piece of foam that was shed.

And in our review the following day of the launch films, we saw this piece of debris drop off, and it looked to us like it impacted the orbiter on the left wing.

Where on the left wing it's very difficult for us to tell. Somewhere between the mid and outward span. Was it the leading edge? We don't know. Was it underneath the leading edge? We really don't know. To the best of our ability, that's what happened. We spent a goodly amount of time reviewing that film and then analyzing what that potential impact of debris on the wing might do and would there be any consequences.

Through analysis and through our ability to call back on our experience with tile, it was judged that that event did not represent a safety concern. And so the technical community got together and, across the country, looked at it and judged

And so as we look at that now in hindsight, that impact was on the left wing, and, certainly, we have all the indications that Milt talked to you about were on the left wing. We can't discount that there might be a connection.

But we have to caution you and ourselves that we can't rush to judgment on it because there are a lot of things in this business that look like the smoking gun but turn out not even to be close. And so we really have to do some regression analysis. We have to look at what Milt described to you and then back up in time through analysis to see if we can piece together or not this was a tile problem or whether it was a structural issue or some other event.

We don't know yet. What will help us determine that is inspecting the debris. That will really help us. And so we're very anxious to get certain pieces back to look at. And that will determine whether or not this particular event, whether it was the debris hitting the orbiter or some other event was the cause of this problem or this disaster today.

That will really help us. And so we're very anxious to get certain pieces back to look at, and that will determine whether or not this particular event, whether it was the debris hitting the orbiter or some other event was the cause of this problem, or this disaster today.

QUESTION: You talked a little bit about the hardware. What goes forward now with the astronaut training? Does that continue? Does that stop? What happens?

DITTEMORE: Well, there's going to be a period of mourning in this community. There's going to be a period where we're just going to get together and support each other and hug each other and help us go on.

But we're going to fix this problem. We're going to get back on the launch pad. We're going to launch shuttles again as soon as we're ready.

The training is going to continue. The best therapy in this business is to get on with your job. The best therapy in the flight control world is to get in that control center and train for the next mission. The best therapy in the flight crew world is to continue with your training, stay focused on the job ahead, stay focused on what we need to accomplish. And that's what we are all going to do.

There's going to be a subset of us that will be working together to resolve this problem. And we will do that, and we will do that quickly, efficiently, and we'll do it safely. And we will not fly again until we have this understood.

In the meantime, life goes on, training goes on. We'll start manufacturing hardware again as soon as we know that we have preserved evidence.

So in a few days, I suspect we will start pulling things back to what we understand and releasing certain activities to start up again. But in the next several days, it's going to be a period of quiet, of reflection, and where are we going to go from here as far as what do we need to do to resolve this issue.

DITTEMORE: No, we don't. We do not have a hardened black-box data recorder or a voice recorder.

We do have recorders. We do have recorders of both data and voice. If they survived the entry and the impact, we will certainly look to see if there's any information there.

As Milt mentioned to you on the time line, he talked to you a little bit about the sensors that just kind of quit working.

We also know that during this time frame, the vehicle was operating perfectly. It had gone into a roll reversal, which is a standard maneuver where the vehicle banks left or banks right; it's a standard maneuver. And when it does so, it does so to bleed off energy. And you do a number of these roll reversals so that you land at the right speed right at the Kennedy Space Center.

It had rolled itself into a roll reversal, and everything from a flight-control perspective was perfect. No indications of any problems. So we have some indications that it wasn't a vehicle loss-of-control issue. And so we're getting some hints of where we need to go look.

Whether or not these recorders survived and will be useful to us, I'm not really sure that's going to be the case.

QUESTION: I have a couple of questions. Regarding whatever it was, the foam that apparently fell off the vehicle at takeoff, was there any consideration during the flight that perhaps an EVA would be necessary, that you need to take a look?

Secondarily, I'm wondering about--you guys talked about loss of sensor readings and some unusual sensor readings. Could you give us a sense of how unusual that is? I mean, does that happen with any frequency, or was that something that was alarming that you had never seen before?

DITTEMORE: The easy answer is the sensor reading, and yes, that happens. The fact that you have a sensor that just quits working is not an alarming factor.

In fact, we understand that several sensors can quit working, and they're all a result of not the sensor quitting to work, the results of an avionics box, a signal conditioner, a multiplexer that happens to fail. And its signature to you and me is it looks like someone just cut the wire.

DITTEMORE: We've seen this on occasion, and we certainly train for it many, many times over. So it is not unusual for us, when we see it, to look at it and immediately start to understand whether it is a single sensor problem or it's an avionics box.

The team today looked at it, as they are trained to do, and could not see any common thread between this sensor and another sensor. There's nothing common about it. So that made it more significant.

And as soon as we understood it wasn't a common avionics box and that there were multiple sensors, all completely independent--and all this happened in a very short period of time--we knew that something was not right.

DITTEMORE: We do not have the capability to perform a space walk and do tile repair. We do not have the capability--as you know, when we go out of the spacecraft, we operate really within the confines of the payload bay.

On this particular mission, there was no remote manipulator system. There was no arm. And so all we had trained to do from a space sidewalk perspective were those things that might be an emergency or a latch did not work and the payload bay door closing sequence or something like that.

We can go outside and make sure they're closed. We have no capability to go over the side of the vehicle and go underneath the vehicle and look for an area of distress and repair a tile.

We know we have no capability. If, for some reason, we thought we had a tile problem, the risk you take when you launch is that you may suffer a tile issue. We have no capability to repair it. All we can do is, before we launch, design robustness into the system so that a loss of some tile capability will not result in loss of crew or vehicle.

DITTEMORE: There is no capability to inspect it. We are not able to look on the underside of the vehicle. And again, our rationale or our retention rationale, why we believe we can continue to fly safely is that we test our tiles on the ground. They're robust, they're hard enough to withstand certain levels of impact. And then we design our environments so that we don't have these circumstances.

We don't believe, at this point, that the impact of that ET debris on the tile was the cause of our problem. We convinced ourselves, as we analyzed it 10 days ago, that it was not going to represent a safety issue.

Now, we had the events of this morning. We're going to go back and see if there's a connection.

Is that the smoking gun? It is not. We don't know enough about it. A lot more analysis and evidence needs to come to the table. So it's not fair to represent the tile damage as the source. It's just something we need to go look at.

QUESTION: There are reports from an astronomer at Cal Tech that the shuttle was--debris was flying off the shuttle as early as a fly-over in Owens Valley in California. How does that match up with this time line? And are you aware of those reports?

DITTEMORE: Well, I haven't heard that report. And sometimes as you go through entry and are in a plasma, sometimes you see plasma. It looks like debris, but it's really not debris, it's plasma. It's just the fact that you're going really fast through the atmosphere.

If he saw something over Hawaii, recognize we flew a good long while before we got to the Texas area. And so it's doubtful that we had something in Hawaii that would cause us a thermal concern.

At the time that we believe we lost the vehicle, at Milt explained, it was about mach 18, or 18 times the speed of sound, we were at our peak heating. We were at 3,000 degrees Fahrenheit on the wing-leading edge.

DITTEMORE: And if we did have a structural problem or a thermal problem, you would--you would expect to get it at the peak heating, not back at Hawaii when you weren't suffering any real thermal environment, extreme thermal environment. The most extreme thermal environment was right at mach 18. And that's where we lost the vehicle.

QUESTION: Yes, Mr. Dittemore, you mentioned in your opening comments that there was indication of excessive structural heating. When did that happen in the time line, from 7:53 and on?

And secondly, at any point between 7:53 and 8:00 a.m., were the folks in mission control worried?

DITTEMORE: Let's see, you respond about the mission control. Let me talk about these bond-line temps.

We mentioned that--and I might have overstated it when I said excessive heating, because as I look at the notes here, the bond-line temps on the left side of the vehicle were off-scale low, which means it looked like the rest of the measurements, it looked like they had been cut. So I probably misspoke on that by saying excessive heating. It really is that we lost those measurements too.

The mood in my area where I observe the flight control team was very upbeat. And then we started to understand a little bit about these multiple loss of sensors. We recognized there was no commonality. We lost voice with the crew. We lost tracking data. We had no TV. As we came to find out later, there were--we saw the TV reports of debris. We did not have that at the time.

And so we were very anxious, because we knew we were in an area of good communication coverage. We were an area where we should have tracking. And we had lost both. And as we starting adding all of these up, the--we were certainly most anxious.

QUESTION: Can you confirm reports of debris in other states besides Texas, namely Oklahoma?

DITTEMORE: I can't confirm any debris in Oklahoma, and I would doubt any debris in Oklahoma because our ground track was basically just north of Dallas on a path that went through northeast Texas, Nacagdoches area, from northwest to southeast. That's going to be the ground track. That's going to be the interest of our search.

Mike Anderson, I suspect you asked me because we are both from the same hometown. Mike and I, we have common backgrounds. He attended my rival high school. He graduated from Cheney High School. I graduated much earlier than he did, I'm sad to say, from Medica Lake High School. And we were arch rivals, and he and I had a good communication going about that.

He was a--he grew up on an air force base, Fairchild Air Force Base, Spokane, Washington. I also grew up in Fairchild Air Force Base in Spokane. He went to the same grade school I did. We had a very common early beginning, but I told him that I was his path finder. And so, we had a good relationship.

And we talked many times about how he had met his wife in Spokane; I also met my wife in Spokane. His parents live there; my parents live there, my wife's parents live there--a lot of commonality.

QUESTION: We heard earlier today that this crew was very passionate about the work they were doing, the scientific experiments that they were conducting. And we heard that their loss would not be in vain.

What I'm wondering is, the--how many of the experiments aboard, in terms of the data being collected, required that the astronauts in the craft return safely to Earth?

And because there were some new laboratory modules on this craft, is there anything to suggest that those could have contributed at all to what we saw?

HEFLIN: Well, Ron, I don't have the answer to--maybe you do--on the number of experiments that we have to have the return of the--I'm don't have that. I'm sure we can get that for you.

And I can't imagine the SPACEHAB being onboard back in the cargo bay had anything to do with this.

DITTEMORE: Let me just says something about the science. This vehicle on orbit, we have kind of pinched ourselves over the past 16 days. This vehicle performed flawlessly, absolutely flawlessly.

Science was a premium. The folks on the ground were just ecstatic with the amount of science that they were reaping. And they were looking forward to getting much of that information back on the ground.

Certainly some of it was down-linked to the ground prior to entry. Some of it was--will be their legacy. Others had to come back and be analyzed, in which that particular part of the science would be lost.

But it was an amazing mission. And we were ecstatic over the results and looking forward to talking to the crew and telling them what a great job they had done. And so it is a painful experience for us to lose our friends and recognize that things were going so well and turned out so badly.

DITTEMORE: Well, a while ago, the last transmission that we got was--it had to do--I think a while ago I discussed that there was a measurement that gave an indication to the crew, an alert, that they acknowledged.

I can't tell you what they said at that time. I don't know what the word was, but it was the sort of thing that when something like that occurs, that the crew's response is fairly typical just to let the ground know that we see that.

HEFLIN: That's how the routine works. And that was the last transmission from the crew that I am aware of.

And I think as we go--you know, as we go through and peel this apart, we'll, you know, we'll have more information like that that we can share with you.

HERRING: OK, got time for two more questions here before I need to go to the other NASA centers. Grab this gentleman and then this young lady on the next row.

QUESTION: A brief loss of communication--has that happened before during reentry? And if so, when you did lose communication, was there still hope that perhaps it was just brief? And at what point did you realize that it was something more grave?

DITTEMORE: We lose communication from time to time for various reasons. We certainly lose it during the orbit phase. We've lost it sometimes for a whole revolution of 90 minutes.

On entry though, we understand that any dropouts generally are brief. And if they do occur, they occur during the peaking timeframes when the plasma around the vehicle is at its maximum extent.

And so, a brief dropout at this time period is no reason for us to be concerned. Our experience is we gain it back fairly quickly.

Our concern at this time was that as we made several calls to them, they did not respond. We made several more calls to them via UHF, which is usually as reliable as anything, and they did not respond. And it became apparent to us that we were in difficult circumstances.

QUESTION: When you guys first got that anomalous sort of readings where you were unclear if, you know, something strange is going on, at that point, was it--was it a situation where you guys were committed? I mean, there was nothing you could have done about it.

And as soon as--when you first saw those readings that, you know, that things went blank or whatever, was there any corrective action whatsoever at that point that you could've done?

DITTEMORE: Nothing that we could do. Just observe and see if there was going to be any future downstream impact of the landing.

In fact, if that's all we did was lose those 12-odd sensors, no impact of this flight at all. We would have come back and repaired the sensors. They don't impact the flying qualities of the vehicle. They don't impact the insight into how we control the vehicle.

All they do is provide us information on how the systems perform, so that when we turn around the vehicle for the next flight, gives us indications of where we should look. Did not affect and would not affect the flight given just the sensor by itself.

QUESTION: Ron, I have a written report from earlier in this flight that there was a potential for a large damage area to the tile. And given that, I'm wondering how and why was it deemed minor by NASA?

And do you have any idea how much of a damage area may have been left on the left wing and how big that piece of foam was that came off?

DITTEMORE: We have a pretty good idea how big the size of foam was. What we don't understand very well was what the actual impact did to the tile.

And so, we have to use our analysis and our engineering expertise to help us understand how a piece of foam of certain weight and density impacting the wing at certain velocity, what it does to the tile.

And our experts gathered together--and we have people in the system that have worked on these tiles since the beginning of the program, and we understand how the tiles function. We understand the tiles' ability to withstand damage. We understand the thermal characteristics of the tile, both on the surface of the tile and at the base of the tile.

And as we got together and reviewed this information, we were convinced, technically and analytically, that the tile would not--the impact of the debris on the tile would not represent a safety-of-flight issue. In fact, we were anxious to come back and get the hand-held film that the crew takes as soon as they get to orbit of the external tank as it's moving away. We ask them to take pictures of the external tank so we can understand exactly where the foam was shed from the tank.

And we were anxious to get that piece of information because we felt that we needed to analyze it so that it would not occur on future flights.

DITTEMORE: We have a flight readiness review coming up for the next flight. It was scheduled for February the 20th. And we knew we had some technical work to do to make sure that we understood why this piece of debris came off.

We were not concerned with Columbia. We felt we had analyzed that and we felt we understood it such that it was not a thermal concern to us, did not represent a control issue or a safety-of-flight issue.

And again, I'm going to caution you that that is the case today. We have no information that would say that is not the case. We are going to go look at it again to see if there is a connection between what Milt talked to you about and the fact that we had a debris impact on the tile. And there are some other things we need to go look at. The tile is just one.

And so, we are satisfied that we did the proper work and across the community, our safety, our quality, our crew members, our flight controllers and the program management reviewed the technical analysis and agreed to a person that it was not an impact to this flight.

So we need to go back and look at that of course, but that's the events as they unfolded.

QUESTION: I'm sorry to ask another question about the external tank, but has this happened before? Has foam come off the tank? Has it impacted the shuttle? And what were the consequences that you saw?

DITTEMORE: We had an event on STS-112 just several flights ago, where a piece of debris from the same general area was shed by the tank. And this particular debris--and I can't tell you today whether it's of the same general size--but it came from the same general area and impacted the aft skirt on one of the boosters.

Superficial damage occurred. When we got the booster back in port and looked at it, evaluated it, reviewed it technically, discussed it at the following flight readiness review, which was STS-113, we as an agency, as a shuttle program decided that it did not represent a technical safety risk to us.

We have, from time to time, debris. Ice can come off the tank, frost, pieces of debris. And they impact the bottom of the vehicle.

Several years ago, we had--we had a problem where we were--as we were during the launch phase, we were popcorning pieces of this insulation on the tile. It would effectively reach a certain point in ascent and it would popcorn out and impact the bottom of the vehicle, and it would cause damage to the tile, but not damage that was a concern from a safety standpoint. Damage that, when we got back, we had to repair or maybe replace a tile.

We have subsequently fixed that problem, and as we were looking at this particular problem of a debris shedding in this one bipod region on STS-112, we said, "Well, we've got an area we need to fix, and we have a turnaround discussion, but not a safety of flight issue."

We flew STS-113. We didn't shed any external tank debris. On STS-107, as we looked at the films on the following day, we saw the same type of debris being shed from the same location.

So again, two occurrences in the last three flights is certainly the signal to our team that something has changed. It did not represent on the first occasion an alarm from a safety point of view. It represented a turnaround processing issue.

As we go forward in our investigation, we're certainly going to look in this area and determine whether or not this was a contributor to the loss of Columbia and the loss of the crew.

QUESTION: Could you talk a little about who all and what all was involved in the analysis of the tile issue at the launch? Did you ever give any thoughts to using telescopes to look for signs of damage to the orbiter? And if you had detected extensive damage to the TPS, is there anything you could have done with the angle of attack or anything else during reentry to have reduced stress on that part of the vehicle?

DITTEMORE: The easy part of that question is there's nothing that we can do about tile damage once we get to orbit.

We can't minimize the heating to the point that it would somehow not require a tile. And so once you get to orbit, you're there, and you have your tile insulation, and that's all you have for protection on the way home from the extreme thermal heat heating during reentry.

We have experience in the past of having events that have occurred that would--that we have assessed using other assets to maybe get a closeup look at the bottom of the orbiter.

Recall a year or two ago, we lost the drag chute door. Right at liftoff, it fell off. And we actually tried to take some pictures of the back end of the vehicle to see what was really there so that we can understand our thermal heating in that case, and those pictures that we received were not very useful to us. So that was part of our background.

Combine that--our feeling that we didn't believe the pictures would be very useful to us--with the fact that there was not much--there was zero that we could do about it, and in this case, we elected not even to take the pictures.

We believed that our technical analysis was sufficient. We couldn't do anything about it anyway. We were in the best possible position, and so we elected not to take any pictures from any other sources, and that's the way it played out.

QUESTION: I'm trying to understand, especially at the first event, the 7:53 event, specifically where those sensors are located relative to the wing structure or the main body structure. Can you describe that in a little more detail, please?

DITTEMORE: Yes, they were located at the left inboard elevon and the left outboard elevon. And recall the elevons are at the back part of the wing, the trailing edge of the wing, and the impact, if you were trying to relate tile damage to the elevon, the impact was on the front edge of the wing.

You can't draw any conclusions from this yet. We can't. It's just data that we need to go pore over and understand.

If you looked at the sequence of events, you would see that our first indication was left inboard out, left outboard which is the trailing edge of the wing.

The next indication was left main gear wheel well which is--it's like it's moving forward toward the front of the wing. But that doesn't mean anything at this point. Because how we lost the sensors was it looks like we just cut the wires. It could be that the wires were being lost at some other location not on the trailing edge of the wing. And so we've got to piece all this together.

We can't say today that there is some significance that the indications started at the trailing edge of the wing and worked themselves forward. We can't say that, just like we can't say a debris impact on the front of the wing of tile is any reason to conclude we lost the vehicle.

It's information that needs to be factored in with a lot of other evidence and analysis, lots more work to do.

QUESTION: I noticed after the disaster, a couple hours after, there was a large number of mission controllers standing for quite some time in the control room. And it looked like they were listening to somebody addressing them. Who was it, and what was the discussion ongoing?

HEFLIN: I'll take that one. We--we are very fortunate here in the agency and, in particular, here at the Johnson Space Center to have people in our employee assistance program, specifically Jackie Reese who runs that program. It is a program to help employees deal with situations like this.

As part of our response to this, Jackie called in and made herself available. So prior to releasing the entry team, both the front room and the room that you see on TV and the people that support in the back rooms, we had everybody gather in that room. That's what you saw.

And Jackie Reese was giving them about five minutes of what they should do as a human being who has gone through something like this. As you leave work and you go home, giving them some assistance and also providing her office to be available if anybody individually needs any help. So that's what you saw. I'm glad she did it. And she's available to help us, and we will need the help in the next several days and weeks.

DITTEMORE: Let me add something to that too. Our communities and our workforce are grieving right now. They're grieving at Marshall in Alabama, and they're grieving at the Kennedy Space Center in Florida. They're grieving here at the Johnson Space Center in Houston, Texas. They're grieving at many of our installations around the country.

And this particular effort will help us get through difficult times for those that really need some extra help. And so we appreciate that service.

QUESTION: You said early in this briefing that you had some hints where the problem may have developed. Could you share those with us?

DITTEMORE: I don't recall whether I said I had hints. All I know is the data that's available to me today, and that is these sensors. It's interesting they kind of work themselves forward from the trailing edge, but I remind myself that may not be the facts.

I have indications of a debris impact on the--on either the leading edge or the wing, leading edge of the vehicle. I have some areas that I know I certainly want to go look at. I have some debris that I'm anxious to see to see if that would lead me down a particular path of investigation.

I have some areas that I know I certainly want to go look at. I have some debris that I'm anxious to see to see if that would lead me down a particular path of investigation. It's one of several that we will investigate, and it's just too early for me to speculate on where that's going to lead.

As you know, we will be thorough methodical, to be a pain in the neck, we will be to make sure we understand it, and it's going to take us some time to pull it all together.

QUESTION: Can you give us the time, I guess you have the initial time when you last lost the data of the conversion and describe what the vehicle was like at that point? You said roll reversal. You gave us altitude and velocity. What is it on autopilot? Was (inaudible) controlling it? What had it been going through at that point?

The MET of loss of vehicle data--thank you, Ron. We'll back up here. We had just completed roll reversal number one. It was completed at an MET of 15 days, 22 hours, 17 minutes and 50 seconds. And he wants the altitude. Thank you, sir. It was 224,390 feet, mach of 20.9.

The--again, as I mentioned earlier, we had no indication of any control problem prior to loss of data. So from a vehicle standpoint, other than what we've talked about that we saw with (inaudible) measurements, we had nothing to indicate the event that occurred. In hindsight, you're looking and saying, "Well, these things were probably tied together somewhere," but we just haven't done that yet.

Loss of vehicle data was at 15 days, 22 hours, 20 minutes, 22 seconds. Altitude 207,135 feet at a mach of 18.3.

QUESTION: I guess for Ron and Milt, could you talk about the issue of Columbia being NASA's original orbiter, the oldest orbiter, how the age issue may or may not be a factor here, and, just out of curiosity, was any of the original instrumentation still on and active that may or may not help you with additional data point?

DITTEMORE: Columbia was an amazing machine. It was the first space shuttle vehicle to fly into space. This was its 28th flight. It wasn't the most experienced vehicle.

Discovery has 30 flights, at least 30 flights if I remember it right. So I don't think age is a factor. If you ever have the opportunity to look at any of our vehicles, you'll see that the vehicles are kept in just pristine shape. A lot of tender loving care goes into the care of our vehicles so that they look brand new.

That doesn't mean that there aren't areas of wear. There certainly are. There are certainly areas of corrosion. That's our job to manage that corrosion and manage that wear so that we continue to fly these vehicles safely.

Columbia, because it was the first vehicle, had a lot more instrumentation included in its design and in its structure than the other three vehicles. And several years ago, we elected to take out much of that instrumentation because it was no longer being used. And we reduced the weight of the vehicle almost 1,200 pounds just by removing instrumentation and the associated wiring.

So there really is no extra instrumentation there that would add to our detective work, and what was there before we took it out was not being used.

QUESTION: We certainly appreciate you appearing here today. I know it's difficult. Could you tell me, please, Milt, if you told the Station crew, I'm sure you have, what's happened, when that happened and what Commander Bowersox and what the rest of the crew might have said in response?

DITTEMORE: Bill, I'm not able to tell you when it happened. Nor am I able to tell you the response. I was clearly not focused in that. I know we can get that for you.

QUESTION: I also wanted to express my condolences to you and your colleagues. You mentioned, Milt, that Americans often wait for a tragedy to come together, and we saw a substantial boost in NASA funding after the Challenger accident.

Ron, I was wondering if you could say what you wish to come about as a result of this tragedy and how much of a hardship would it be if you have to fly the shuttle manifest with just three ships?

DITTEMORE: My thoughts are not on what I hope to come out of this tragedy. My thoughts are still on what happened this morning. My thoughts are on seven families, children, spouses, extended family. My thoughts are on their grief. My thoughts are on what we missed, what I missed, to allow this to happen. It's going to be a difficult day. For all of us.

QUESTION: Ron, a two-part question. The first part may be a little repetition, but I want to make sure I got it clearly. Do you have any indication at all that there was excessive heating on any part of the space shuttle, whether it was wing or tires, landing gear, and secondly, would there be a possibility that there's anything associated with the bipod that could have come off (inaudible) along with that foam?

DITTEMORE: The first part of the question is, no, we really don't have any information that says there was excessive heating.

And so when I said that earlier today, I misspoke. All we do is have information that says the sensors quit working.

And if we do have evidence of excessive heating occurring, I will get back to you and let you know. I think we're going to hold some meetings with you on a fairly regular basis over the coming days, and I will bring you up to speed on if anything that I said today was erroneous. And certainly as we get new data, I'll let you know.

As far as the bipod area, we believe it was foam. We do not believe it was any metal. We don't believe there's any opportunity for any metal to be shed. And in fact, our films show that when this particular debris impacted the wing, there was a puff, puff of debris, like when it hit, it disintegrated itself. And so I don't believe there's any chance that it was hardware. It was all the soft foam insulation.

QUESTION: Is there any indication from what you learned so far, Ron, in this incident, that maybe the stress or maybe overstressing this space plane in the roll reversal process? I think, at one point, the left banking got up to 57 degrees.

DITTEMORE: Yes, that is not uncommon to have that type of roll reversal and banking (inaudible). In fact, we've seen a lot more--a lot steeper banks than what you just mentioned.

We'll have to go back and look to see if that is a factor. That will be part of our gathering the debris, inspecting that debris and seeing if there is anything there that would give us a clue as to whether this was structural in nature, a structural failure, or whether it was thermal related or some other.

So we're going to have to be some detectives and look at the debris and gather that evidence to determine what the cause was.

QUESTION: If you had had a sudden break in the heat envelope or sudden heating, would that have knocked out the sensors, or would you have expected to have seen a heat measurement before they quit working?

DITTEMORE: Well, it's certainly speculative to try and understand the relationship between any thermal environment and whether that thermal environment would have translated into an area of wiring and then destroyed wiring.

Hard for us to respond to that question today. Be glad to take that question in the coming weeks as we get some information where I can respond to it factually.

HEFLIN: You know, you guys are trying to help us, and we thank you for that. I mean, you know, you can continue to ask questions like this, but you know, anything that--everything would be a speculation. And that's not fair, it's not accurate, and I know you want to be accurate.

HERRING: Well, let me interject, because we also need to recognize these two gentlemen have been on duty since about midnight last night.

So I want to bring up a point that we are going to do--try to do briefings daily, at least daily. So please try to form your question appropriately so we can get through today. And then I need to get them out of here fairly soon.

So I need to wrap up with KSC as quickly as possible. I've got some other NASA centers to get done also before I wrap up. So let's make two more at KSC and then move to headquarters, please.

If you can, can you tell us all how the families are holding up under the circumstances, the families of the astronauts?

DITTEMORE: See, we don't have any firsthand knowledge. And I believe earlier in the day Mr. O'Keefe and Mr. Readdy talked a little bit about how the families reacted both with our administrator with the phone call from our president. So I don't have anything to add other than what was said previously.

QUESTION: I was wondering, after the loss of communications, did you notice any deviation in the flight path of the shuttle?

DITTEMORE: When we lost communications, we also lost our ability to track the vehicle. And so, we had no indications whether or not we were off the flight path. We had no indications that we had a break-up. Only later, as we reviewed the TV coverage, did we see that there was a break-up.

HEFLIN: And you know, in the control center, just to share with you, we have plots of the trajectory and how we're flying.

And I and I know others stared at that for a long time because the tracking ended, you know, over Texas, stopped. And it was--and I reflected back what I saw with Challenger.

QUESTION: Could you give us an idea of what your investigators are going to be looking for at Michoud and when they're going to start looking?

DITTEMORE: We had already kicked off an effort even prior to this morning to try and determine why the debris was being shed from that bipod region of the tank.

And the reason we kicked off that effort, because we knew we needed to understand it prior to the next flight. So we were already aggressively on a path that was helping--that was going to try and help us understand whether or not that represented any concern to us since--since now we had it two times in the last three flights.

That was a major element in our planned flight readiness review for STS-14 scheduled for march. So that activity was already in place, already ongoing.

What we have done today is asked--asked our external tank project team and Lockheed Martin, which is the contractor for the tank who builds the tank in the Michoud facility in Louisiana--to isolate certain pieces of hardware, to gather data that might be pertinent to this discussion and to make sure that we have not put in jeopardy any piece of evidence that might be helpful to us.

So we've taken those steps. Those are in place, ongoing right now, and we'll be able to keep you aware and tell you what's happening in the coming days, if there's anything that comes out of this.

QUESTION: What are the contingency plans for the International Space Station in the event of a grounding of the shuttle fleet for an extended period of time?

DITTEMORE: All I know today is that I've talked with our station program management.

They have been in contact with all of the international partners. They understand what happened today in the shuttle program.

They are going to proceed as planned tomorrow to resupply the station via the progress vehicle. There is a Soyuz launch that is planned later in the spring, and we know that we have sufficient consumables on board to go through the end of June without any shuttle support.

Beyond that, I have no further information. I hope that we get this situation resolved in the coming weeks, so that it isn't an extended period of time, but that remains to be seen.

In the near term, we know we have months of adequate supply on board the international space station, and we also know that we can help resupply them from our international partners' resources. So that's what I know today, and we'll see how that matures over time.

QUESTION: Could you tell us any more about how you approached the recovery of all the debris that is spread over such a large area and what the NTSB's role is going to be in that or in the investigation and also how long you think it will be before you know more about what happened today?

DITTEMORE: We have many government agencies that are helping us respond to this tragedy. The NTSB is at our disposal. We have the FBI that is involved with us. We have local and state law enforcement. We have FEMA that is also helping us tremendously.

We have been assured that we will have the assets and the efforts of the--of our government to help us wherever we need to gather debris, get it in the right locations, identify any crew remains, get them to the right locations.

All that is ongoing. It's being organized. It's a tremendous effort that has been engaged and is in the process of coming together from all different agencies and different parts of the country.

DITTEMORE: As these things come together and as we start basing and we start collecting, I'll keep you informed on just how that is going and where these things are happening, and certainly, we'll respond to your questions as this moves along.

QUESTION: Are there any satellites that NASA, U.S. Military or commercial satellites out there that might have caught what happened and will you be looking at images from other satellites? And just about the debris as well, you mentioned earlier that you were anxious to see certain types of debris. What types are you anxious to see, and are first responders trained for the recovery of such hazardous materials?

DITTEMORE: Well, we were anxious to see the pictures of the tank. As we separate from the tank roughly 8.5 minutes after launch, we have the crew immediately get out of their seats and use some handheld, both still and motion picture video, take some shots of the tank as we're separating from it, and we do this on a routine basis because that's our only evidence of what the tank looks like after it got to orbit because the tank goes about a half an orbit around the earth and reenters through the atmosphere and is destroyed, so we have no physical evidence other than film.

And what we were anxious to see was that film, to see if it looked similar to what we had experienced on STS-12 where we shed some debris from the same area.

Obviously, we're not going to get that information. So that's what we were looking for. And if you've asked me any other parts of that question, I've forgotten what they were.

QUESTION: It looks like, judging from the TV reports, what you've been finding are these smaller pieces of debris. Is it NASA's intention to try to gather as much as possible and then to try to rebuild the shuttle much the way they did with TWA flight 800?

DITTEMORE: I don't know for a fact, but my impression is we are going to gather every piece we can find, treat this much like an aircraft incident and see if we can solve the puzzle.

That's not going to be very easy because when we had this vehicle break apart at 200,000 feet and mach 18, it was at peak heating, and some evidence may have burned up during re-entry. Other evidence is just spread over such a wide territory that we may never find it.

So we hope to get as much as we can, piece it together, as experts think best, to help us solve the puzzle.

And let me make another plea to limit your questions to one. And I've got 15 more minutes for this briefing, and I'm cutting it off for the day, recognizing we are going to offer briefings at least daily from here on in.

QUESTION: I understand the Marshall Space Flight Center managed the key propulsion elements of the shuttle. What specific involvement will the center have in the investigation?

DITTEMORE: They, along with every other center, will be actively involved. We will have their key managers, their technical experts, all coming together, much like the teams we formed when we solved the flow liner problem of the summer and the recent BSTRA crack that allowed us to launch STS-107, the resolution of that issue.

So we're going to pull together the management. And we've already had meetings with the center directors. We've already had our meetings with our management at headquarters. We're already assembling the technical experts in the teams.

And so we're going to make wide use of their best and brightest to solve this problem and try to understand what happened and put in the proper corrective action.

QUESTION: Can you tell me if you learned anything from the investigations of Apollo I and Challenger that will help this investigation proceed more quickly?

DITTEMORE: I think the--what we are implementing today is a process that has been tried over time. And many of what we are--many of the procedures that we are implementing today were a lesson learned or an outgrowth from previous incidents.

And so we're learning our lessons. We're putting them into practice and what we have put into place today is the result of previous lessons learned.

Just a side personal note: It is our mantra or our personal effort to learn the lessons of the past, it's a mandatory reading for us to read the reports from the Rogers Commission on the Challenger accident. We study them. We understand them.

We try our hardest never to repeat the problems of the past. And it was all of our goals never to have to sit in front of you and describe these events again. And we're very disappointed. It's hard to tell you how disappointed we are, how saddened we are at this event.

And somewhere along the line, we missed something. We're going to learn something new that we couldn't do anything about, but I guarantee you, we're going to fix it.

QUESTION: Could you tell me who is on NASA's rapid response team from Marshall, what the role will be, and what role Marshall was playing in the foam debris investigation from the external tank?

DITTEMORE: Well, there are many superb technical experts at the Marshall Space Flight Center that are going to be involved in this investigation. I don't have at my fingertips today the names of those individuals.

If we judge it appropriate in the coming days to release that, we certainly will give that information to you.

QUESTION: Can you tell me who's leading this investigation from a center perspective? Is it coming out of Johnson, or will it come out of another center?

We have a mishap investigation team that is a standing team in case we have events like this happen. The chairman of that will mishap investigation team is Mr. David Whittle. He is a trained individual in mishaps. He has gone to NTSB school. He works very closely with the other agencies. He is NASA's commander on the scene. He is the one that's leading our effort. He is on his way to our staging areas, and he will be our prime interface with all the other agencies to help us resolve this problem.

So just a talented marvelous team that we'll have pulled together to go do this, and it's a team that is named prior to each flight, standing ready just in case we have to do just these types of things. Hopefully, we never plan to use them. In this case, they're trained and we have pressed them into service.

QUESTION: There have been 49 landings here at Edwards Air Force Base. When the Challenger disaster happened, it's my understanding that there was a two and a half year hiatus. You have mentioned within this press conference that future flights might be held. Can you tell me what the impact of today's terrible events will have on us here at Edwards Air Force Base?

DITTEMORE: Well, I suspect they're not going to--you're not going to feel much impact at all at the Edwards Air Force base complex.

Edwards is used as our secondary landing site in case we have bad weather in Florida and do not have sufficient consumables to attempt to get into the Florida and Kennedy Space Center facilities.

Recall in Challenger, one of the reasons why it was such a long delay was because we had to do some hardware redesign to make ourselves--to get ourselves the confidence that we were safe to fly.

That hardware redesign was necessary to be implemented, to be developed, to be tested and certified, and that took some time to do.

We'll just have to see how this particular tragedy works through the same type of engineering and technical scrutiny. If there is some hardware change, we'll just have to work through that. And we'll work through that with dealing with the requirements that keep us safe to fly, the development and design certification, testing type of process.

Too early yet to say whether or not that's going to be the case. And we'll let you know how it proceeds.

QUESTION: How is NASA responding to the families? What has NASA told the families? And what are families saying today? How are they reacting and responding in light of all this?

DITTEMORE: I believe earlier in the day, Mr. O'Keefe made a statement that reflects the reaction of the families and their heroic manner that they took the news. And I don't want to add any more than what has already been previously stated as to their reaction.

HEFLIN: And they will have a huge--they'll have a huge amount of support, you can guarantee it, from this family here and this family across the nation.

QUESTION: How many tiles in a given area of service, specifically the area where the sensors were located, could be lost before that might cause some catastrophic breach of that surface?

And what do you do in flight if you have that catastrophic breach and you know about it prior to re-entry?

DITTEMORE: I really don't know how many tiles. I can't really respond to that question here today.

Our only recourse is to design this vehicle such that we don't lose tiles, is to design this vehicle so that we can take debris impacts and not represent a safety concern.

It's been our experience that we have lost portions of tiles on the bottom of the vehicle. We have had a number of debris impacts damage to the tiles. They have all been acceptable in that they do not represent a safety-of-flight concern.

We would like to get a harder tile to make it more resilient to debris, but it has not, to date, represented a safety concern.

And we have no recourse if we lose tiles. Our only effective action is to prevent the loss of tiles through design and through test. And that has been perfectly adequate up to this point.

There will be a B-roll package for the STS-107 mission that will follow this briefing immediately.

The next briefing that we will hold is likely to be around noon central time tomorrow, but that's a very tentative time because there are some--obviously some management meetings that these gentlemen are taking part in that will occur prior to that tomorrow. So right now we're looking at around noon central tomorrow for the next briefing here.

Also, there is a lot of folks out there that are--that may discovering some debris from the accident. NASA has established a telephone hotline, also an electronic mail address, for the public to use for reporting information that may help in the investigation of this accident.

The telephone line--and you guys can certainly help us in this regard--is 281-483-3388.

The website that right now should be online for folks to provide either text reports or images that they think may be helpful in the investigation for us, that website address is nasamitimages--all together--nasamitimagesjsc--for Johnson Space Center--at jsc.nasa.gov.

So--and we will try to build a billboard or something like that that we can put on NASA TV as well to help folks with that.

So again, the phone number is 281-483-3388, and that is for the NASA hotline that has been established.