|Columbia Accident Investigation Board Public Hearing
Monday, April 7, 2003
3000 NASA Road 1
Board Members Present:
Admiral Hal Gehman
Major General Ken Hess
Brigadier General Duane Deal
Dr. Sally Ride
Dr. John Logsdon
Mr. G. Scott Hubbard
Mr. Steven Wallace
Col. James Halsell, Jr.
Mr. Robert Castle, Jr.
Mr. J. Scott Sparks
Mr. Lee Foster
ADM. GEHMAN: Good afternoon, ladies and
gentlemen. This public hearing of the Columbia
Accident Investigation Board is in session. We're
privileged to have with us today two experts to help us
see our way through some of the issues that we have to
deal with, and we're going to deal with the treatment
of anomalies and waivers and certifications and all
that sort of stuff today. We have a panel of two -- I
don't know if you'd call them experts or not; we'll see
at the end of the day whether they're experts or not --
but to help guide us through the first part of this
process. The first is Colonel James Halsell, who is an
astronaut and has a couple of duties, one of which is,
I presume, to command a mission here in the future, I
trust; and Robert Castle, who is from the Mission
Gentlemen, before we begin, let me ask
you to first to affirm that the information you provide
the board today will be accurate and complete, to the
best of your current knowledge and belief.
THE WITNESSES: I do affirm.
JAMES HALSELL and ROBERT CASTLE, JR.
testified as follows:
ADM. GEHMAN: Would either one of you
start and introduce yourselves and tell us a little bit about your background but also tell us what your duties
COL. HALSELL: Okay. I'll start first,
sir. It's my privilege to be here to have the
opportunity to work toward what certainly anybody at
NASA considers to be one of the most important things
we'll ever do in our career -- that is, to find out
what happened, to fix it, and get back to flying
I have a background in the Air Force.
I'm an active duty Colonel in the Air Force. My
background in aviation was fighter aviation, followed
by test aviation, and then an assignment to NASA for
the last 13 years, since 1990 as an astronaut. I had
the privilege of flying five missions; and at the
conclusion of my fifth mission, I was asked to take on,
as a career-broadening experience, a management job
down at the Kennedy Space Center as a launch
integration manager, working directly for the program
manager, Mr. Ron Dittemore. I did that from the summer
of 2000 until January of this year, when I was relieved
of that job in order to take my next assignment, which
was to command STS 120, which will be a mission to the
International Space Station, taking up Node 2, one of
the hardware components that will complete the American initial phase of the construction of the station.
If you'd like, at this point in time I
can talk to you --
ADM. GEHMAN: Before we do, let me ask.
Do you also have a role in the return-to-flight
COL. HALSELL: Yes, sir. I received word
just two weeks ago that I would be requested to head up
a return-to-flight planning team. We would be doing a
staff planning function, reporting directly to the deputy associate administrator for station and shuttle.
That's Retired General Michael Kostelnik. Our job is
to be his interface to the shuttle program and, in
fact, throughout the NASA system working this issue, to
come forward with recommendations and options in
response to the Columbia Accident Investigation Board's
findings and recommendations. So the way it should
work is that once your investigation board wraps up
with a report, and hopefully even in the interim before
that final phase, we'll have the opportunity to map out
a response to your investigation board's findings and
recommendations. I'm sure that we'll come down to a
set of options that we'll offer up to our leadership
and our management and they will make some of the tough
choices that have to be made with regard to what has to be done to fly safely again, what needs to be done in
the long term to make the system even safer.
ADM. GEHMAN: Let's let Mr. Castle
introduce himself, and then you can start.
MR. CASTLE: Okay. I'm very honored to
be here and take part in this, in the return-to-flight
effort for the Columbia. A little bit about myself.
I'm a full-time career civil servant. I've been
working for NASA for 25 years now. I started working
one of the mission control sections as a communications
officer, did that for about ten years, and then was a
mid-level manager for about a year and then was
selected for the flight director office in 1988. So
I've spent right at 15 years as a NASA flight director,
running missions in Mission Control.
I have recently left that job to become
the Missions Operations Directorate chief engineer and
currently working on things like orbital space plane
and some upgrades in the control center as well as
contributing work on the International Space Station.
I should also say I was a shuttle flight director for
virtually all of that time. The last two years or so,
I've switched over and become mainly a flight director
on the International Space Station. That started
around the middle of the year 2000 was when I did that much more than I did shuttle flights. So that's my
current role to date.
ADM. GEHMAN: Thank you very much.
Colonel Halsell, if you have a statement or perhaps a
presentation, we're ready to listen.
COL. HALSELL: Yes, sir. I did come
prepared with a presentation package. Certainly I
would expect -- and feel free, as I'm sure you will, to
ask me questions as we go along in this somewhat
It's my understanding that I've been
asked here today to give you any information that I
might provide with the preflight process. In the
shuttle program we call it the Flight Preparation
Process, FPP for short. So if I use that acronym, that
will be what I'm talking about. And that is the
all-encompassing phrase, if you will, for everything
that we do to get ready to go fly safely, including a
subpart of that is the Certification of Flight
Readiness and all the reviews and boards that we go
through for that.
Before I launch off into the details, it
might be helpful if we just review the basics. The
basics are basically this. The way the shuttle program
is set up -- and I believe correctly and appropriately so -- is we have a set of requirements. It is huge,
long list of requirements. It's broken down by the
projects and the elements and all the contributing
manufacturers, but the space shuttle program is
responsible to be the keeper of the list of
requirements. It tells us how we're going to build a
component, how we're going to use it. It tells us how
we train the crews. It tells us how we prepare the
vehicles. Everything we do answers back to a
requirement; and before we go launch a shuttle mission,
it's absolutely required that we know we have lived up
to and, in a closed-loop accounting fashion, answered
each and every one of those requirements successfully.
In a perfect world, you would have your
requirements on one hand and before we go to launch,
you'd have absolute and utter proof that you met each
and every one of your requirements. We do live in that
perfect world except there is such a thing as a waiver,
in the sense that oftentimes if you can't meet the
intent, indeed, the scripture of a requirement, then
you have to come forward to the program, and
specifically the program manager, and make the case for
what you are offering instead is sufficient to allow a
complete productive and safe mission. If you can pass
that test, then with the waiver we are allowed to go ahead and fly.
So it's requirements, closed-loop
accounting system, and to the degree to which they
don't match up perfectly, we enter into the waiver
process. That's the 37,000-foot view of what we do,
and almost everything that we talk about from this
point on could be tied back to that very simple basic
I know that after Challenger, it was
recognized that these processes were not as disciplined
and as rigorous as they should be; and I believe what I
hope to tell you today and what I hope comes out of my
presentation is that following the Challenger disaster,
we went back and did rigorously enforce that
discipline. In the degree to which we fell short in
the Columbia accident, that's why we're here today and
that's what we want to find out.
I think it might be helpful just to lay
out a couple of other basic thoughts. The shuttle was
designed with the philosophy that you should not have a
system in which you suffer a failure and you lose your
vehicle or your crew. It needs to be fail-safe.
Furthermore there was a high operational desire to be
fail-operational -- that is, suffer a failure and still
complete the mission. The basic requirements are that the vehicle and all of its subsystems will be
From the very beginning, there were three
of the systems which it was acknowledged we could not
achieve that desired goal. The thermal protection
system was one. It was recognized as being a
Criticality 1 -- that is, if it doesn't work, you're
going to lose the vehicle and/or the crew and we don't
have a backup system to it. Pressure vessels, whether
it's the pressure vessel in which the crew resides or
the pressure vessels which holds our fuels and our
oxidizers and our cryogens, was another. And finally
the primary structure of the vehicle. The vehicle was
not built with the intent that you could lose anyone --
you could always guarantee that you could lose one
primary load-bearing piece of the structure and still
maintain your safety margins. So those are the three
areas where the design of the vehicle, it was
acknowledged, would not live up to the basic
requirement of being fail-safe.
On the other hand, in the area of
avionics, they designed it with a higher than
fail-safe, that is, a fail-operational requirement. In
our avionics area, it was designed to be able to suffer
any one failure and continue to nominal end of mission. Those are my opening thoughts and maybe background that
might help you as we delve down into the flight
preparation process in detail. So with that, if I can
press on to the next slide, please.
This is a flow chart that shows you the
program level reviews. Each of these represents a
review, a large meeting of all the relevant NASA and
contractor personnel; and it's also just a program
level. Below each of these program level reviews is a
vast array of project level reviews, but let me just
briefly go through this and it will give you the
outline of what we do and how we do it.
Starting in the upper left-hand corner,
the Flight Definition Requirements Document. That is
the bible that a flight, a mission, in the preparation
of a vehicle for that mission, where it all gets laid
out. Normally this is presented to the Program
Requirements Change Board, which is the program
manager's venue for considering these top-level issues,
about 16 months prior to flight. You can go from the
front of the vehicle to the tail of the vehicle and
talk about the level of detail, but basically that
first block should be preceded by two or three years of
preceding blocks where our customer and flight
integration office receives inquiries from our potential customers to understand what payloads they
want to fly, what mission requirements they are
considering, and that's mapping those against the
shuttle capabilities and whether or not we can satisfy
those requirements. In a very complete iterative
process we go through understanding what do they want
to do, what is it that we're able to do, and to the
degree that it doesn't match up, let's try to better
understand how we might be able to force a match there.
When you get to the FDRD, you know the
vehicle you're going to fly on, you know the size of
the crew, you know how much cryogenic oxygen and
hydrogen's going to be on board, because that drives
how long the mission can be because, of course, that's
breathing oxygen for the crew and that's also what we
use to generate electrical power for the payload and
for the other systems on board the orbiter. You know
exactly what the payload configuration is going to be
in the payload bay, down to the keel and the trunnion
attachments on the side walls of the vehicle. You know
probably the serial numbers of the engines you're going
to fly. It baselines everything there is that you
really need to start out to do the detailed final
preparation for the mission, and that baseline can only
be changed from that point on by going back to the Program Requirements Change Board and asking
So that's the FDRD, and it's really the
first milestone at the program level. The other blocks
as we follow along there have names which are fairly
self-explanatory of what they do and what we're there
to do. The Cargo Integration Review highlights and
further refines details with the payload that we're
going to be carrying for that mission.
The Ascent Flight Design is a
program-level review because that is understood to be
the most dynamic phase of flight. It's the one where
we have to tailor the software the most from flight to
flight, given any one of a number of variables, not
only the payload you're carrying and the weights
involved and the load of propellants that you're going
to carry on that particular flight. So we bring that
to the program level.
The FPSR, the Flight Planning and Storage
Review, is the one that's near and dear to most crew
members' hearts because that usually happens at about
the ten-month-or-so month prior to flight and that's
just about the time that the crew has just been named
and has started working together as a crew. So that's
the first one that the crew normally supports; and the Flight Plan and Storage Review, it really summarizes
the issues which are most importance to the crew. The
flight plan tells everybody, including the crew, what
you're going to be doing every second of every mission;
and if you can nail down the flight plan and make it
answer back to the requirements of the flight, it's a
lot easier on the commander to be able to plan his
mission and to plan his training for his crew, which is
one of the primary jobs of the commander pre-launch.
The other important part is stowage.
Living on board the space shuttle and working on board
the space shuttle has been likened to a camping trip in
a closet in that you have to know exactly where
everything is so you can get to it in a timely fashion
and you also have to get it back in the right place
before you come home. And the degree to which you
don't know that or you make it more difficult than it
has to be, it directly impacts your ability as a crew
to get your work done. So you try very hard after
you're first named as a crew to get to the Flight
Planning and Storage Review and understand the degree
to which we have a high level of fidelity in that
planning process, because that's your first clue as to
how much work you have in front of you in planning the
mission, the details of it.
The next three blocks really have to do
with the same subject, and that is at the Kennedy Space
Center what are they going to have to do after that
orbiter lands from its previous mission until you
launch it on its upcoming flight. The first block, the
Integrated Launch Site Requirements Review, is where
you hash out what are the actual requirements. You
know you've got to be able to get the payload into the
payload bay. What are the requirements before and
after and leading up to that event? What are the
modifications that you want to do on this vehicle? At
any given time in the shuttle program, there is usually
a list of modifications which are ready to go to be
implemented in any given vehicle, and you have to weigh
is now the time to try to insert any of that particular
modification to bring the improvements that it does
either to the capabilities or to the safety level, or
do you have to understand that the manifest at its
current state is such that work would be better
implemented one flow following this flight. So you
make those trade-offs and those kinds of determinations
at that time.
Then the Kennedy Space Center comes back
at the Launch Site Flow Review and they tell you their
ability to meet those requirements and that they're going to be able to do it and to the degree that
there's a mismatch, we hash it out at that meeting.
There's one other meeting, the Delta
Launch Site Flow Review. By the way, the timing is 60,
, plus 15. That is, it's about two months prior to
the landing of the orbiter from its previous mission
that you really try to nail down the requirements.
It's about one month prior to that landing that you do
the flow review and have Kennedy come back and tell you
if they are going to be able to accomplish it. After
the landing from the previous mission has accomplished
and they've been able to roll the vehicle into the
processing facility, you understand better the
condition and any in-flight anomalies which it had
during the previous mission, how that might impact what
you had planned to do previously. You bring that back
to the program at the Delta Launch Site Flow Review and
that's where you make any final determinations and
judgments on what we are and are not going to do on
this particular flow. If necessary, you adjust the
launch dates to meet those requirements.
So that's the program level review,
starting at 16 months prior, to actually up to two
weeks after the landing of that orbiter and you start
to process the vehicle. This is what's typically referred to as the flight preparation process.
The last block that I'll lead into with
the asterisk is called Milestone Reviews, and this is
going to be where we now tend toward more of a
Certification of Flight Readiness flavor for what we're
doing. If I could have the next chart, please.
I believe I've talked about all this. So
if we could press on to the next chart.
The next chart, please. Here we go.
Here's the wiring diagram to talk about the milestone
reviews and the certification of flight readiness that
results from this process. The chart flows from the
left to the right. On the left-hand side, you have the
different projects and elements, each one responsible
for a particular major system on the orbiter. On the
far right-hand side, you have our flag -- I'll call it
our flagship review, the Flight Readiness Review, which
typically happens about two weeks prior to launch,
where we present all the information to senior NASA
management to determine the final readiness for launch;
and everybody's required at that point in time to sign
up to the Certificate of Flight Readiness. In between
is an incremental improvement at each step in our
ability and a refinement in our ability to say, yes, we
are headed toward the satisfactory Certification of Flight Readiness.
Starting at the left on the project
level, their major review would be the Element
Acceptance Review. That's where the government project
manager will accept from the contractor the piece of
hardware. Once again, there's a whole hidden set of
pre-reviews that led up to the Element Acceptance
Review. I've talked to a number of project managers
and I think they'll all tell you it would be totally
unacceptable for them to be surprised or to hear an
issue at the Element Acceptance Review that they did
not previously know about.
So it's worked in real time, but we do
lead up to the EAR for each major component of the
vehicle. Then where I've gotten involved in my job as
the launch integration manager are in the two
double-bordered boxes that you see there. The ET/SRB
Mate Review and the Orbiter Rollout Mate Review. Each
of those represents a processing milestone that we want
to be very careful and we want to be very studious, if
you will, before we go through that milestone, without
taking a breath and stopping and pausing and making
sure we're ready to go do that.
I approach it from the point of view of
two aspects. First of all, those mate reviews were my opportunity as the integration manager to actually
understand the rationale that was going to be brought
forward at the Flight Readiness Review for any of the
major waivers, hazards, first-time flight items,
changes to processes, in-flight anomalies to be
considered up to that point in time. It was my
opportunity to hear that in a formal forum and to
understanding how they were going to present it to the
Flight Readiness Review.
Now, let me make it immediately clear
that, just as it would have been unsatisfactory for a
project manager to come to an Element Acceptance Review
that did not know everything that he was going to be
told, it would be equally unsatisfactory for me as the
launch integration manager to come to a mate review and
not know the details of everything that was going to be
presented and have had a history of having known the
development of all those issues over the prior months.
Nevertheless, that's the first time we put it all
together in one package.
ADM. GEHMAN: Let me interrupt. This is
where -- I mean, you mentioned this. I just want to be
clear about this. In the Element Acceptance Review,
these EARs, as well as at these program reviews,
previous waivers and waivers that are currently in existence, disposition of old in-flight anomalies would
all be brought up, kicked around the table, and if they
had been accepted in the past, the acceptance would be
COL. HALSELL: Yes, sir. I believe I
understand the intent of the question. There is a
requirement both at the project level and at the
program level for us to fully understand in-flight
anomalies as they apply to that particular piece of
hardware and the mission that's about to be flown.
There's a requirement to review and understand all the
waivers that had been issued and, in particular,
concentrate on any change of waivers or any new
waivers. If it's a waiver which has previously been
approved through the program and through the entire
system and there is nothing different about it's
applicability or this flight as compared to the
previous flights, then it's not necessary that it be
brought forward again and again and again; but what is
absolutely required is that any new waivers or changes
to waivers be highlighted at each of these progressive
ADM. GEHMAN: Just from an administrative
point of view, if a system over a period of 20 years is
operating under 25 waivers -- which, by the way, that's probably not an outlandish number; it might be more
than that in some cases -- how does the system deal
with the fact that a waiver's starting to accumulate.
COL. HALSELL: I am aware during the time
that I was at the Cape that the program approached that
exact issue at least on a couple of occasions. Just
before I took over as the launch integration manager in
the summer of 2000, my immediate predecessor, Mr. Bill
Gerstenmaier, under Ron Dittemore's direction, had gone
through a review of the waivers. The question was:
How many are out there? Are they all still valid? How
often do we review this situation so that we're not
guilty of unknowingly accumulating waivers? To what
degree are we confident that we have good rationale for
retaining waivers in place?
What we found out from that review is
that we do have a good process in place. There's an
annual review of the waivers to make sure that it is
still appropriate, it's still applicable, it's still
necessary. Remember, we should probably back up a step
and just talk a little bit about how you go through the
process of granting a waiver. What you want to do, to
the degree that you can't meet the requirements that
you have in place, you want to try to change that and
satisfy the requirements. So your first goal would be to try to execute some type of design change that
allows you to satisfy that requirement. To the degree
that that's not possible, then you look at other
mitigating factors, if you're able to put warning
devices or safety systems in place or a crew or ground
work-around procedures in place which mitigate the
risks. Those are the kinds of things that have to be
part of the acceptance of the residual risk when you do
go forward with a waiver.
ADM. GEHMAN: Okay. Thank you very much.
That answered my question. So the kind of legacy
waivers then are reviewed annually or periodically,
depending on what the project manager wants as a kind
COL. HALSELL: Right. Once again, we
concentrate most directly -- in the Flight Readiness
Review process and the Certification of Flight
Readiness for a particular flight, what you want to
know is what's changed from this mission to the
previous missions or those waivers which need to be
highlighted due to the operational flavor of this
particular flight and maybe being different from recent
previous missions. You'll make sure that those
differences, those deltas, as we call them, that's what
you bring forward. The same would be true for the failure modes and effects analyses, the hazards, the
program hazards. So there is a family of processes
which we sometimes capture in this one word "waiver,"
but they're all reviewed and all brought forward as
required during the Certification of Flight Readiness
process to make sure that we're not guilty of missing a
waiver rationale that is in need of review prior to
that upcoming flight.
MR. WALLACE: You said that it would be
unusual at an Element Acceptance Review for something
to come up that you hadn't heard of previously. I have
to say in the weeks learning about the FRR process and
even the Launch Readiness Review just done in the days
before the launch at the Cape that this is sort of a
recurring message, like the work is kind of done before
these meetings. I'm curious is it fair to say that
these meetings, then, don't get scheduled until the
work is done or is it unusual things get stopped at
these meetings? Does the meeting become sort of a
COL. HALSELL: I guess the best way to
answer your question would be to talk a little bit
about my personal experience in this area. When I
stopped flying on a shuttle crew for a while and I went
down to be the shuttle launch integration manager, I perceived some of the same flavor that you're talking
about. That is, the important work was being done and
being done exceptionally well -- so well, in fact, that
when we got to some of these milestone reviews, it
appeared to me that all of the hard issues had been
discussed, all of the hard decisions and trade-offs had
been made. So I questioned the value to our senior
management of these level of reviews; but after being
in the job for a longer period of time and after having
discussed this situation with a number of my project
managers, they had a different point of view. They
didn't disagree with the fact that the way we do
business is such that most of these problems, not
always, but most of them, have been flattened out prior
to the formal review, but it's because of the presence
of those formal reviews and the fact that you know that
senior NASA management, the people that you answer to
and the people who are ultimately responsible for the
safety of the upcoming mission, 'cause you know they're
going to be there to hear that story, it drives all
that outstanding work that happens before. So from the
point of view of the projects and the elements, they
did not want to change or consider any dramatic changes
to the forum or to the agenda of any of these reviews
because, from their perspective, they were driving the kind of reaction within the system that was healthy and
DR. LOGSDON: If I heard what you just
said correctly, then what's presented to the senior
managers is the situation after things have been
smoothed out. How much visibility do the senior
managers have to the process of resolving issues prior
to the formal reviews?
COL. HALSELL: Let me see if I can say it
in a clearer fashion. I believe that the senior
management within NASA, since the Challenger disaster,
serves a critical role in deciding upon the final
readiness to go fly safely, and it's our job as the
middle-level managers to provide them with the
information that they need to make that determination.
I believe that the process we have in place works very
well to do that. I believe that absolutely if we get
to a Flight Readiness Review where there are any
outstanding issues or if there are any issues that need
to be discussed to the infinite level of detail for
that level of management, we do that; and I can recount
a number of instances where a Flight Readiness Review
which was marching along according to the agenda and
there were no particular issues, we would come upon one
that required the next hour of discussion. It would require a number of people to stand up ad hoc and
discuss their participation and their rationale. The
Flight Readiness Review board, as would my board on the
orbiter roll-out and the mate reviews, if there was
something fuzzy or something that we did not agree with
or something that we needed additional clarification,
we would delve into those details at that board, up to
and including the flagship review, the FRR. The point
I was trying to make earlier was it's knowing that you
are subject to that level of review and that level of
detailed review, if necessary, that drives all the good
work leading up to it.
DR. RIDE: This may not be quite the
right time to ask this question. Maybe it should be
further on in your preparation, but you've now
mentioned twice that since the Challenger accident,
processes have been improved and put in place. I just
wonder whether you could elaborate on that and maybe be
a little bit specific about changes that you are aware
of. There were, of course, FRRs before 51L, PRCBs
before 51L, senior management was pretty heavily
involved in the key meetings leading up to a launch.
I'd just be interested in your assessment of what
changes have actually taken place.
COL. HALSELL: Thinking back to some of the Challenger findings and recommendations, I believe
there were ten major findings and recommendations and
then appendices behind that. I know that NASA
responded to each and every one of those. The two that
come to mind, one that's particularly important to me
because it has certainly affected my life, was the
thought that we needed to involve the astronaut corps
in more of the middle and, if appropriate, later in
their career, senior management jobs because bringing
that operational expertise over to the managerial side
of the house was value added to the entire system. I
do know that, for example, immediately after the
Challenger accident, a number of astronauts were
consciously moved into management positions and we have
retained that priority for astronauts as part of their
career progression ever since then. I don't know the
degree to which astronauts were involved prior to the
Challenger, but I know that, after, the answer has been
quite heavily and in numerous occasions.
I know that another finding from the
Challenger commission had to do with the fact that on
the specific decision to go ahead and fly, given the
new data that was brought forward the night prior to
that launch, that information, that discussion, the
dissenting opinions and the method of which it was finally decided that we were going to go fly that day,
all that was not brought forward to senior NASA
management in a timely fashion; and I truly believe
that today, given the processes that we have in
place -- and you'll hear more about the Mission
Management Team later on -- that would not be the case.
That issue would have been elevated to the appropriate
level, given the same set of circumstances today.
DR. RIDE: I guess I was just curious
whether you could point to any specific -- and again,
this may not be the time -- but any specific parts of
the process that have been added or specifically
strengthened in the pre-launch process.
COL. HALSELL: I guess I can speak to the
strengths of the processes that we have in place. With
regard to the details of comparison how it was
pre-Challenger, which was prior to my participation, I
probably would not be the right person to ask; but when
I get to the part about the Mission Management Team and
the process that's in place, I would invite anybody who
is knowledgeable about being able to compare that
specifically to what we did pre-Challenger to help me
GEN. HESS: Colonel, before we get too
much further in your briefing, which might be in question, I was curious about providing some balance in
the discussion with regards to the line
responsibilities to the requirements meetings and these
various reviews and how that is balanced by the S&MA
organization and recalling the Rogers Commission saying
you needed an independent safety process. So if you
could help us out at these various stages and give us
some idea about how safety figures in and whether or
not they can actually overturn one of these meetings
because of their degree of questioning over any
particular portion of the mission as it's going.
COL. HALSELL: Let me answer the last
element of your question first, and the answer is
absolutely yes. On each of the reviews that I've
participated in, whether it be the orbiter roll-out
review or the mate review, the safety community is
represented through several different channels. Also,
the pre-launch Mission Management Team review at
O minus 2 -- that's launch day minus 2 two days -- and
then at the Flight Readiness Review, Safety is always
there. They're always represented and they are always
polled and they always expected to come forward with a
dissenting opinion which would cause everything to stop
at that point in time and we not progress to the next
review on the right side of that chart until we had it hashed out. So that's the answer I want you to hear is
that Safety absolutely has not only the ability but the
requirement to step forward if they believe that the
engineering community is headed down a wrong path.
I believe that's the essential element of
one of the strengths of the processes that we put in
place. That is, that, in my opinion, a large part of
your safety that's built into the system is
accomplished through the strength and the viability of
your engineering community and their in-house safety
work that they do in line. But it's also important --
and I know that Ron Dittemore has always felt very
strongly about this -- it's also important that we have
an independent over-the-shoulder assessment of how
we're doing from the safety community also. And the
important aspect that we've always worked hard on is
making sure that as we do our job in line, we have that
independent assessment looking over our shoulder and
then the fact that they are staffed, have the
resources, and empowered to give that independent look
at what we're doing. That's the fundamental strength,
I believe, in the process that we have in place.
ADM. GEHMAN: Colonel Halsell, we're
using the term "waiver." You already said this. I
just want to clear it up. We're using this term "waiver" kind of loosely here because it really
characterizes a number of administrative steps that are
taken to account for processes. Can you mention what
some of those other ones are called?
COL. HALSELL: Yes, sir. Some of the
other categories that we talk -- for example, hazards.
Hazards are a top-down look. You start with a fairly
limited number of ways that you can lose a vehicle or
crew and then as you drill down deeper and deeper and
you spread out farther and farther, you understand the
more detailed failures that could cause that hazard to
be recognized. The shuttle program is designed to
avoid these hazards and, to the degree we are not able
to do that, then we try to control them. You control
them by looking at your design and implementing
changes, if possible, or the safety controls or warning
devices or crew operational procedure work-arounds that
I talked about earlier.
ADM. GEHMAN: Is that what you referred
to as a FMEA?
COL. HALSELL: Well, a FMEA CIL is
actually a different process. It's a bottom up. It's
where you talk about, all right, what if that component
of that box failed? Then at the box level, what if
this avionics box fails or this component within my auxillary power unit hydraulic system fails? What's
the worst thing that could happen to me as a result of
We have requirements within the system,
as I explaining at the beginning of the discussion,
with regard to our willingness to expose ourselves to
risk. We always want to be fail-safe. We desire to be
fail-operational. The degree to which we're not able
to meet -- and you also use a risk matrix approach, if
you will, in analyzing some of those risks associated
with the different failures. Basically it boils down
to looking at what is the probability of an occurrence
of a particular failure and what are the consequences
if that happens. Depending upon where you fall in that
risk matrix determines whether it's unacceptable, in
which case you don't fly and you make a decision to go
fix it -- and I can give you examples of those kinds of
cases -- or if it's an accepted risk because you
believe that the mitigations that you have in place
make the combination of probability and consequences a
safe situation for you to go fly in. Then a totally
controlled risk is where you don't believe there is any
significant risk that you're being exposed to.
ADM. GEHMAN: If we took a case like the
cause celebre of the day, foam hitting the orbiter, if during the course of the years that foam shedding and
foam hitting the orbiter had been previously waived and
had previously been disposed of, it's likely it would
not even have come up at the ET review. Let me
rephrase that. That's a question, not a statement.
COL. HALSELL: Yeah. And I believe my
correct answer to your question is that I don't believe
that to be true. We'll use that as an example, if we
want to pull on this thread a little bit. I think it's
well known that we did liberate a piece of foam on
STS 112; and the process by which we went through
understanding what had happened, how that related to
our previously accepted hazards and FMEA CILs and what
was the appropriate course of action from that point on
all followed the processes that we had in place to try
to ensure that the right decisions and the right
trade-offs and risks got made.
For example, in the in-flight anomaly
situation for STS 112, that did come to a Program
Requirements Change Board. It was decided there that
an in-flight anomaly designation was not required for
this particular item because the previously accepted
and documented hazards -- and if I remember correctly,
there were two integrated hazards which were violated
or which were called into question by this particular instance -- two of them dealing with the external tank
liberating foam and creating a hazard to some other
vehicle component -- there was nothing about that
particular instance which invalidated the rationale for
the previously accepted risk. In other words, we
didn't move up and to the right on the risk matrix,
according to what we knew at that point that time. So
the action that was levied at that Program Requirements
Change Board was to the external tank project to go
back and fully understand what had happened, why it had
happened, and what we were going to do to keep it from
happening in the future. Also another action was
levied to bring that item forward at the Flight
Readiness Review to make sure it was discussed prior to
STS 113. So using that as my example, I would say that
that's an example of how the process worked properly
and the item was brought forward to the Flight
Readiness Review and it was discussed at some
considerable length there.
DR. RIDE: How would that have been
different if it had been classified as an in-flight
anomaly after 112? What would have been different in
the disposition process?
COL. HALSELL: Nothing. In the sense
that whether it's designated in-flight anomaly or not, the important item is that two PRCB directives were
issued at that time which directed the project to go
back, analyze the problem, find out what it is, and fix
it. Another action was issued to make sure this was
brought forward to the Flight Readiness Review. So
whether it's designated an in-flight anomaly or not,
the answer is it would have made no difference.
Now, let me jump ahead and make sure that
I'm not guilty of not answering the question you meant
to ask, which is, if we had designated at the highest
level, which is in-flight anomaly with constraint to
next launch, then it would have been immediately an
issue which had to be not only fully understood but
resolved either with an engineering design change or an
appropriate rationale for flight and formally
documented. So on this particular case, I would
maintain that that process was worked, because we did
discuss this issue at the STS 113 Flight Readiness
Review at some length. The process of making sure we
felt comfortable and safe and that we understood the
risks and the hazards and that there were no
significant changes from those that had been accepted
in the past, all that was done, despite the
classification that we came forward with at the PRCB.
MR. WALLACE: If I could follow up. I understand from reading some of the PRACA documents
that all PRACA reportable items must be dispositioned
in some way -- I mean, prior to the next. Is that a
COL. HALSELL: Yes, it is. However,
there is sub-documentation that gives you guidance by
which projects are allowed to enter into interim
disposition as opposed to disposition prior to the very
next flight. And it was the consideration of that
particular set of guidance, of rules, along with what
we thought was an understanding of no significant
increase of risks due to the liberation of STS 112,
that led the PRCB to decide that the appropriate way to
deal with that particular issue was to issue the
directive for the external tank project to come back
and find it and fix it and tell us what they had done
and also discuss it prior to the Flight Readiness
Review. In general, yes, all problem resolution
reporting and corrective action items have to be dealt
with. The level at which they get dealt with depends
upon the criticality, Criticality 1 being the most
significant and requiring the highest level of
managerial insight and concurrence with. On the other
end of the spectrum would be Criticality 3, which means
you have no risk of loss of vehicle or crew. Those can sometimes, under the guide rules that we have written
down, be dealt with at the project level and with
different combinations in between going to different
levels of management. I would hasten to add that, as a
project manager or as a program person, you don't have
the right to decide, on any given day, what level it's
going to go to. That's all been decided for you, and
it's documented for us in our processes.
MR. WALLACE: So this item which was a
PRACA reportable item but not an in-flight anomaly on
12, there was an interim disposition?
COL. HALSELL: Yes.
MR. WALLACE: Which then didn't include
any hardware changes -- it wasn't an assignment to --
COL. HALSELL: We can read the exact
directive; but paraphrasing as I remember, it was:
"ET Project, you've got until the 5th of December --
and I think that date was later extended due to some
conflicts of scheduling -- but you've got until the
th of December to go find out exactly what happened,
reinforce for us what you're telling us today, which is
you have no reason to believe that it's a generic issue
and that we're at any increased risk on the upcoming
flights of suffering this problem. We would like your
options for engineering design changes which could be implemented to completely alleviate this problem in the
future. Come back and report to us what your options
are and what your recommended plan is."
MR. WALLACE: Could you tell us about the
decision-making, I guess it was in the post-112 PRCB,
the roles of different elements in the decision-making
as regards the classification, in-flight anomaly or
not, and the decision to go with an interim deposition,
particularly the external tank element and the S&MA
office, if could you speak to that.
COL. HALSELL: I'm trying to think,
Mr. Wallace. What additional information or what
avenue are you trying to get me to talk about
specifically that I haven't talked about already?
MR. WALLACE: Just really focus on who
makes the call on that, on the in-flight anomaly
decision and on the interim disposition items.
COL. HALSELL: You're doing a good job of
doing my presentation for me -- and that's fine.
Let me. If I can go to the final two
slides, if I remember, in the presentation, prior to
the backup. Let's cover the two in-flight anomaly
pages. After every flight, or as you're doing the
flight, every element, every project, including Mission Operations Directorate, which Bob will have an
opportunity to talk about here in a moment, they're
compiling their list of things which have happened
during this flight. Sometimes you hear it called the
funnies list or the action log. It goes by a number of
names depending upon which element or project you're
talking to. I'll use the name "funnies list." That's
everything that happened that was worthy of attention
by somebody. In general, that entire list, all the
problems, all the elements, all of their funnies get
brought to the Program Requirements Change Board.
Usually it's the first one following the landing of
that vehicle. Sometimes it goes to the second PRCB.
The program documentation says we need to do it no
later than two weeks after landing, is our general
It's a fairly long and detailed PRCB
agenda item where you go through each and every problem
that you experience, all the engineering information
that you know that might have caused it, and the
elements first blush on where we need to go from here.
As part of that and as we go through each and every one
of those items, it's a PRACA reportable item. You
never have the option of saying, well, thank you very
much but I don't think that's worthy of my attention. Everything gets dispositioned one way or the other, and
part of the process that everybody is focusing on
appropriately in this discussion is in-flight anomaly
What you see before you are the listing
of rules by which the funnies can get elevated to an
in-flight anomaly. Just to go through them briefly, if
it's a Criticality 1 or 2 -- meaning that we threaten
the loss of vehicle or the crew, Criticality 1, and
Criticality 2 meaning we threaten loss of a normal
nominal mission, that's worthy of in-flight anomaly
consideration. If it's software, either orbiter flight
software or the space shuttle main engines, it could
cause Mission Operations Directorate -- and Bob can
probably give us examples of these kind of situations
where we got the nominal mission accomplished but they
had to work extra hard and had to do a lot of
work-arounds on orbit to make that happen -- then we
don't want that to have to happen again. So we deal
with that as an in-flight anomaly.
If it caused or if it could have caused a
countdown hold or a launch scrub or a launch abort,
then we want to deal with that. If it could have
affected safety or mission success or caused
significant impact on resources, logistics, or schedules for the future, or if it's any anomaly that
the designated responsible design element wants to make
an in-flight anomaly, they have the final word. So
that's a list of things that we use as criteria for
consideration as in-flight anomalies.
If I could have the next slide, please.
As far as interim deposition is concerned, these are
some of the items by which it was appropriate for us to
give the elements more time to deal with these issues
and not call them constraints to the very next flight.
Let me run through those. Remember, it's one of the
following criteria: If it's not applicable to the
flight -- in other words, whatever broke last time,
you're not flying next time, that's obvious; if the
problem condition is clearly screened during pre-flight
checkout or special tests and you know you're not
subject to that same problem; if the problem is
time/age/cycle related and the flight units will
accumulate less than 50 percent of the critical
parameters by the end of the upcoming flight; if
there's no indication that this is a generic problem or
if you have no overall safety-of-flight concern; if the
problem is applicable to flights, however, the PRCB
agrees that we have sufficient evidence that the system
can be flown safely with acceptable risk, then those are the kinds of circumstances under which we would go
to an interim disposition. And it's my belief that it
was the consideration of these type of issues which led
to the determination that the external tank foam, using
that as an example, would be an appropriate issue for
us to talk about completely at the upcoming FRR but to
give the project additional time to come forward with
their corrective action.
MR. HUBBARD: I'd like to go a little bit
to the hand-off between the end of one mission and the
beginning of another. You just characterized what you
do post-launch. Now, let's go pre-launch to the next
mission. What is the process by which the collection
of things that have happened over the various missions
get put into a data base or some kind of a memory bank,
other than just individuals around the table so that,
as the missions go forward one after the other, you
build up a sense of trends? You know, maybe there's
nothing on one specific flight, but maybe there's an
accumulation. How does that get brought to the
attention of management during the review process?
COL. HALSELL: I believe the answer to
your question is PCAS, which stands for Program
Compliance Assurance System. Lately the new word is
web PCAS in the sense that its been upgraded to a web-based system, and previously it had been a
mainframe-hosted computer system. Web PCAS is a
web-based system which allows any person associated
with the program at any level, including senior
management all the way down, to access all the sub-data
bases. PRACA's been -- the problem resolution
reporting and corrective action system, that's one of
the sub-data bases which is part of PCAS, for example.
The waivers list. The in-flight anomalies list. The
FMEA CILs. All of these data bases -- and we could
probably go on for quite some period of time to have an
exhaustive list -- are part of the web PCAS which the
engineering community and the safety community use
equally in this type of trend analysis and in what we
characterize as the paper close-out that has to happen
before we go fly again. Before we fly, we have to be
0 percent sure that we have our requirements and our
closed-loop accounting system has sufficiently -- you
can't launch if you simply know nobody's elevated a
problem. You have to have the reassurance that people
have looked and that they have closed out all of the
open paper, and it's only upon that positive
affirmation that you can go fly.
MR. HUBBARD: So just to follow this one
step further. This data base is available. Is there anybody who is charged with actually looking at it and
as you go around the FRR and these other reviews
saying, wait a minute, to take our favorite topic, I
see a trend in foam-shedding or something like that?
COL. HALSELL: Yes, sir, and there are
two somebodies. Every project and element -- and
you'll see the participation in the Flight Readiness
Review -- every project and element associated with the
program has to say that verbally at the Flight
Readiness Review. They are signing for that when they
sign the Certificate of Flight Readiness that, yes, we
have looked at this and we know we have closed out all
these issues; and the independent assessment that we
were talking about earlier, that's an important part of
their function in ensuring safety is they look over our
shoulder and they make sure that every project and
every element has closed out those issues appropriately
ADM. GEHMAN: Could I ask you to go back
one viewgraph here. I don't want to talk about STS 107
specifically. We're talking generic processes here,
but I would like to talk about foam-shedding as a
generic process. So if you can go back one viewgraph,
please, to the in-flight anomalies, the IFA. Thank
Okay. So as I understand it -- and I
don't know whether this viewgraph comes from NASA
regulations or procedures or where it comes from, but
I'm going to assume it's accurate for right now -- we,
of course, will check that out -- it says there that
any one of the following criteria makes it an IFA. I
assume that damage to TPS, since it's Crit 1, that
Item A there, any problem that affects a Crit 1 system
which is damaging TPS, we've got ourselves an IFA.
COL. HALSELL: Yes, sir. I mean, reading
No. A, that's what it says; and I would once again draw
your attention to the second page which we've already
covered, which gave further guidance which would allow
an interim disposition.
ADM. GEHMAN: Now, I want to go to the
second page. Once again, I'm not talking about the FRR
of STS 107. We're going to go into that in some
detail. I'm using this as a generic case. It looks to
me like something hitting the thermal protection system
or damage to the thermal protection system is a Crit 1
system and therefore anything that hits the TPS ought
to be an IFA, looks to me, just using this score card.
And if we look through the disposition here, it says
that interim disposition is acceptable or a final
closure is required if you meet any one of the following criteria. So I look at A, problems not
applicable to the flight we're talking about -- that
doesn't apply. A problem condition is clearly screened
pre-flight -- that doesn't apply because you can't tell
what piece of foam is going to fall off. C doesn't
apply because it's not age related. D, I would say,
doesn't apply because it's a generic problem and can
happen anytime and anyplace else. Then we get down to
E: There is no safety-of-flight concern. Now, can you
tell me how -- or even the last one: The board agrees
that sufficient evidence exists that the system can be
flown safely. How in the world does the system
determine that there's no safety of flight? Do you
know what processes there are involved or is it
COL. HALSELL: I know you say we're not
going to discuss and this is not STS 107 related, but
it is ET foam related. So continuing with that as our
example, as I remember, the particular presentation at
that PRCB, the nature of the rationale that was
presented in that forum was that the external tank had
gone back even at that point in time before they had
responded to the following action and they had
vigorously tried to understand did we do something
different with the tank where we had this problem as compared to all the other tanks which had flown
successfully. What came out of that was they felt
comfortable that there was no new and generic issue
that they could identify, either with changes or
weaknesses in their processes in applying the foam or
manufacturing or in the vendor that provides the raw
material. They had already gone back and looked at all
of that and they felt comfortable at that point in time
that they had no generic issue that indicted follow-on
future tanks that we were going to go fly.
Furthermore, I do not know for a fact that it was
presented in that form but I do know that as part of
the Boeing transport mechanism there was no elevated
level of concern that anything liberated from that
location would have impacted the orbiter. What all
this added up to was the conclusion that we had not
moved up and to the right on the risk matrix with
respect to the previously accepted hazard, the two
hazards that had been accepted and which we had flown
for much of the life of the program, I believe, since
ADM. GEHMAN: Thank you for that. To
follow up on Mr. Wallace's question, is it the PRCB
that would make that decision that there is no safety
of flight or -- I mean, it wouldn't wait for an FRR; you would have settled this some other way, I presume.
COL. HALSELL: It isn't the Program
Requirements Change Board, that the program manager has
the ultimate responsibility for determining what are we
going to classify as an IFA, what are we going to
classify as an IFA with constraint, and which are we
going to classify as an interim disposition with an
action assigned to come back at a later point in time.
But also it's important to understand that the Flight
Readiness Review, upon review of any of those actions,
certainly has the ability to upgrade any item that they
so deem necessary.
ADM. GEHMAN: Absolutely.
DR. LOGSDON: I am going to ask a
question about STS 107. If the mission had been
successfully completed, would the foam shedding have
been classified as an in-flight anomaly and, if so, by
what criteria, since there was an analysis that said it
was not a safety-of-flight issue. It was
COL. HALSELL: I want to make sure I
answer exactly the question that you're asking, and
it's in the context that we have had the foam
liberation on STS 112.
ADM. GEHMAN: No, what he's saying is Columbia gets struck by foam just like she did but she
COL. HALSELL: Yes. Absolutely. And
given that we have now had a second occurrence --
DR. LOGSDON: Go back to the prior slide.
COL. HALSELL: Before you do, just
remember "D" there about the generic problem. At that
point in time, I have absolutely no doubt that
following the STS 112 incident and it happens again on
7, what you now have on your hands is a major issue
that has to be dealt with before we consider even
rolling out the next vehicle, much less flying the next
MR. WALLACE: And the fact that on the
7 it struck the orbiter, does this even make it way
more clear that this would rise to the level of an IFA?
COL. HALSELL: Especially given that the
Boeing transport analysis seemed to indicate that we
were not at severe risk of having a strike against the
orbiter from a piece of foam liberated in this area.
Now, to be complete and fair -- and I know you know
this -- that same transport analysis also indicated
that there were weaknesses in the program that was
being used to do this analysis. Perhaps most
specifically, they made the assumption that you were dealing with a non-lifting something and that as soon
as you implied some lift in a direction, then that
would have to undergo further additional analysis that
took that into account.
ADM. GEHMAN: Why don't we let him move
GEN. DEAL: Well, I'll go ahead and ask
you an opinion question here, Jim, a little bit. It's
based not just on your extensive experience in the
shuttle but also your flight test experience. If 1 out
of every 25 flights you're flying a test development
vehicle and it drops a panel forward of the intake, you
know, I would think you would be a little bit
concerned. We talked to some test pilots that say the
deserts around Edwards are littered with panels out
there, but, you know, I equate foam falling off of a
bipod and hitting some part down below that's critical
to the flight as being something forward of a jet
intake. Can you give us any perspective about if we
showed the right level of concern with four previous
bipod ramp incidents where the foam broke off as
compared to what type of precedents we put on it.
COL. HALSELL: I understand the context
of the question you're asking me. As a test pilot and
somebody involved in the job of acquiring the data with which a vehicle that's going to be flown for hundreds
of thousands of hours over the fleet and making sure
that we vet out all those issues while we're in the
test phase, as opposed to in the operational phase,
trying to transfer that experience to what we're
dealing with here. One of the limitations that we've
had over the entire life of the shuttle program is that
we've never had the opportunity to accumulate the
number of flights and the number of flight hours and
the number of occurrences of any particular item to be
able to apply the same statistical rigor that we're
able to do in flight tests, for example, where you do
quickly accumulate that kind of experience. I think
trying to draw that analogy or that comparison might be
an error on my part. So I would ask that I not be
asked to do that because I don't feel comfortable doing
I will take what I think is the intent of
your question, and that is at the point in time when
STS 112 occurred, we had not had a loss of ramp foam,
if I remember correctly, since approximately STS 50.
There might have been some interim problems with ramp
foam, but nothing of that size and significance.
Following STS 50, they had changed some of the
procedures and some of the foams; and we thought that had been an improvement in our processes and in our
materials. So when STS 112 happened, whether it was
appropriate or not, I think there was a consideration
that this was a new occurrence, given a new baseline,
and trying to statistically infer that what had
happened prior to those changes were applicable to our
current configuration was not appropriate. I'm sure
that that consideration will be something that the
investigation board will feel charged to draw an
GEN. DEAL: I've got two other questions.
Since we're controlling your briefing for you, if we
can go back to Slide 10, I've got a question for you
because we haven't covered that one yet. We bypassed
When I look at the FRR, Jim, I see a lot
of people in there. Some of them are former
astronauts. Is the mission commander involved in this?
Are the current astronaut corps involved in the FRR?
COL. HALSELL: The Flight Readiness
Review, the flight crew is represented to the board or
the Flight Readiness Review through several different
avenues. The center director for the Johnson Space
Center, the astronauts are hired and work for that
person. So he represents their interests. The manager of the space shuttle program --
GEN. DEAL: On the three that you
commanded, did you attend the FRR? Were you a part of
it at all?
COL. HALSELL: No, I did not; and,
furthermore, I think that that's the right thing to do
because sitting right behind the board, not at the
board table, as the commander of a shuttle mission, I
have my direct and immediate two people I consider to
be my reps to the board. That is the chief astronaut,
that's currently Kent Rominger; and the director of
flight crew operations, currently Bob Cabana. Those
two individuals, in my opinion represent the flight
crew, the flight crew interests, the flight crew point
of view, and that's who I want to be there and to
concur with any issues having to do with the Flight
Now, I think there's a page of presenters
here; and I forget if it's forward or backward. But
very close to here is going to be the agenda. There we
go. You should see flight crew and the left-side
halfway down, the flight crew operations director will
make his presentation to the Flight Readiness Review
board as to the readiness of the flight crew to press
forward into launch countdown. At that point in time he's certifying that the crew has been fully trained,
is ready to go fly, they have all the procedures,
they've been trained on all the procedures, they have
all the equipment and training on how to use it to
accomplish the mission. Bob Cabana, the FCOD director,
doesn't just stand up and say that. In preparation for
the Flight Readiness Review, he has a pre-FRR at which
the commander of the mission does attend; and it's at
that meeting here at the Johnson Space Center
approximately three to four days prior to the FRR.
It's the face-to-face meeting where the FCOD director
queries the crew commander and asks him: Are you ready
to go fly this mission? Do you have any concerns? Do
you have any issues? So I feel 100 percent justified
in saying that even though the flight crew is not
physically present at the FRR, they are 100 percent
represented in terms of their ability to make it known
to anybody and everybody if they have a question.
I guess I feel like I know something in
this particular area that I would like to express.
There are about 100 meetings that you don't want the
flight crew to go at. Because at this point in time in
their training, two weeks prior to launch, that's when
their highest task loading is. That's what they're
trying their hardest to -- it's actually now in the preceding two or three months they're trying to congeal
together as a crew, ingrate all the procedures, all the
issues, and at this point in time they're typically
involved in the terminal countdown demonstration test
where they go to Kennedy Space Center and participate
in a full dress rehearsal where from the time you wake
up that morning until you do the simulated emergency
egress out of the vehicle, every step from waking up,
suiting up, going out to the briefings, going out to
the pad, getting strapped into the vehicle, going
through all the procedures of the last couple of hours
of the countdown, that's what you're concentrating on.
And I would maintain that as important as it is to make
sure that there's a chain of communication from the
command to senior NASA management, it's also important
that we don't overburden them with an unnecessary
requirement to be at certain meetings. We just need to
make sure they have that communication path; and I
believe certainly for all our reviews, including FRR,
ADM. GEHMAN: Go ahead.
GEN. DEAL: I've got one more follow-up,
but I can wait.
COL. HALSELL: Did I miss a question?
ADM. GEHMAN: No. Go ahead.
COL. HALSELL: With the presentation?
I've kind of forgotten where I was.
ADM. GEHMAN: Page 6.
COL. HALSELL: Okay. Thank you, sir.
Let's see we were talking -- the vehicle preparations.
Element Acceptance Reviews. And I think I got through
the external tank mate reviews. And we got taken down
what I -- I said there were two things that as the
launch integration manager I tried to concentrate on on
the mate reviews. The one we covered in a lot of
detail. I called it the paperwork, but it is the
close-loop accounting system to make sure that we have
positive affirmation, that we have met all the
requirements, that the rationale for the waivers that
we need to go fly with are in place and still valid.
The other part I'll call the practical
side. As the launch integration manager, I did not
ever want to be guilty of getting caught having gone
through a significant milestone such as mating the
external tank to the solid rocket boosters or, later,
rolling the orbiter out of its protected processing
facility and bringing it over to the Vehicle Assembly
Building, going vertical and mating it and then finding
out that there is something not right, something that I
should have known about at the mate review or prior that, in hindsight, would have stopped me from going
through that milestone. After you mate the orbiter,
for example, you don't have nearly the access that you
do in the orbiter processing facility. So there was a
practical side to those mate reviews that it was
important to make sure we had full understanding of,
Next slide, please. This slide probably
does a better job than I did verbally of answering a
question earlier of is there a process by which all the
waivers, all the FMEA CILs, all the open hazards, any
upgrades in hazards or FMEA CILs, that it's all brought
forward, what is that closed-loop accounting process
that we make sure we're ready to press forward to the
next level of readiness. This slide gives you that,
and I think we've touched upon some of the important
elements of that.
Next slide, please. Now we're talking
about Flight Readiness Review, which I think has been
done. Let me see if there's anything on this chart
that we haven't really talked about. I think the
important thing to understand is that the Flight
Readiness Review exists at its core for the associate
administrator of the Office of Space Flight, Mr. Bill
Readdy now, to make a final determination if he feels comfortable that we have done everything that we said
we would in our requirements to get ready to go fly
Next slide please. This slide should
look very similar to the one that I presented two
slides ago because it says basically the same thing.
We review all the open issues, make sure that our
baseline configuration, what we're flying is what we
said we were going to go fly and, if it doesn't, that
we understand why and that we agree with that. Any
significant unresolved problems or resolved problems
since the last review and the flight anomalies, any
open items on constraints, any and all new waivers and
any open actions from the Flight Readiness Review or
any of the element reviews that led up to that have to
be closed out at this meeting.
At the formal end of Flight Readiness
Review -- could I have the next chart please. I'll
continue my thought in just a moment.
Here is the participation of the board.
What I might have in the backup charts but, if I don't,
I want to make it clear to you, that this is not just a
table with these people. It is, rather, a table in the
center of a very large room with these people
surrounded by literally hundreds of other people. Every project, every mid-level and lower-level manager
of each project is represented there, each of the
contractors, from the CEO down through every individual
that he or she thinks is necessary to provide the
necessary support. Literally a couple of hundred
people at least are attending these meetings and are
right there in the same room.
Next slide, please. Some of the
logistics are talked about here. We try to hold this
review a couple of weeks prior because that's soon
enough so that if we identified any issues at that
point in time that need to be dealt with, we have some
chance of still making a launch date after having
satisfactorily resolved those issues. You don't want
to do it much earlier than that, though, because you're
reviewing a flight for which issues and problems are
going to arise in the interim period of time. So that
seems to be the right middle ground.
We talked about how all the NASA and
contractor personnel are there. One important aspect
is that we insist that the whole world of the space
shuttle program travel to the Kennedy Space Center and
be there in person. You do not participate in the
Flight Readiness Review by telecon. You will be there
and, if you can't, your designated alternate will be there. It's that face-to-face conversation,
face-to-face interaction, that allows you to gain so
much more information than you can from a telecon and a
voice transmitted to you over the telephone. So the
face-to-face nature, I think, is something that's
Also not only do we have minutes but we
audio- and video-record the proceedings. I know, for
example, in answer to Dr. Ride's previous question,
that's one thing in particular I remember was
implemented post Challenger that we hadn't done such a
good job of previously. Maybe we had been as good at
analyzing some of our issues, but the documentation of
the way we resolved those issues wasn't as stellar as
we would have liked. We made sure that problem was
fixed, hopefully, after Challenger.
MR. HUBBARD: This is a little bit of a
subjective question, but let me start off with just a
fact or two. You participated in FRRs as the manager
of launch integration, and what you described is a big
show. I mean, it's a big deal and it's a big room and
a lot of people. Somebody once said if you have more
than five people at a table, it's not a meeting; it's a
conference. So you've got, as you said, a couple of
hundred people, more than a hundred people in the room. What do you feel like when you're in an FRR? What do
you think the tone is? You know, people have their
antennae quivering, looking for issues? Do they feel
like their working their way through a series of boxes?
How do you feel when you're going through an FRR?
COL. HALSELL: I feel like it is the
culmination of a very, very long and involved process.
I feel like when we're there in that room, we are
putting the important final touches on the work of
thousands of people. It is thousands of people. Tens
of thousands of people. That filters up at the
engineering and manufacturing level, up through the
element processes and reviews and the element project
managers to what I'll call the mid-level to upper-level
management that I participated in in my reviews as the
launch integration manager. But it certainly wasn't
just me. There are a lot of other mid-level managers
doing the same thing in their areas of responsibility.
And I feel like the Flight Readiness Review is that
flagship review at which we have that last and final
opportunity to present our story to senior NASA
management. And we know that they've been made aware
in an interim basis on everything that we've been
doing. But I feel that at the table at the FRR board
you have the representatives of the right organizations to lend that final not only senior managerial level but
that experience viewpoint and common sense viewpoint
and asking the straightforward simple questions: Have
you done this? Have you accomplished that? Why do you
feel comfortable that your assumptions that you made
here allow you to make the conclusions that you're
presenting to us? I feel that that's the level of
inquiry that we get at the Flight Readiness Review,
especially on issues that require that at that point in
time. So I feel like it is an appropriate and
exhaustive review that culminates an appropriate and
MR. HUBBARD: Just one follow-up on that.
People, in general, can feel very comfortable saying
things one on one, maybe even in a group of five or
ten. I don't know if your average engineer -- and, of
course, this is a group of senior managers -- but do
you think people feel comfortable raising an issue in a
room with a hundred people?
COL. HALSELL: I know that in this
particular forum there's absolutely no hesitation to
raise your hand, even if you're sitting with your back
up against the back wall, against the wall of the
building -- and it happens every FRR. And I would
simply volunteer to bring forward transcripts and also recordings to back up what I'm telling you. It would
be highly uncommon for somebody not to interrupt a
presenter in the middle of their presentation and say,
"Well, now, wait a minute. How can you say that when
we had something else happen two years ago which now
seems associated. What do you think about that?"
At some points in time, as the
secretariate, if you will, of this particular
presentation, my issue has not been with getting full
and free participation but just making sure I get it
documented. I've got to stop people. I've got to say,
"Please come forward. Make your way to the microphone.
We need to get this recorded. We need to understand
what you're trying to tell us." So my issue has been
just to make sure that those types of input are
recorded and documented properly. So I do feel that
the Flight Readiness Review is a full and open forum.
DR. LOGSDON: If there is that kind of
lively interaction at the FRR -- and this is really a
question asked out of literal ignorance -- have there
been FRRs that have resulted in a decision that the
mission was not ready to fly?
COL. HALSELL: Yes, sir. We have a way
and we have a process to document that. It's called
the Exception to the Certificate of Flight Readiness.
Next slide, please. I'm trying to see if
I have it up here.
Next slide, please. Okay. We'll stop
right there. What happens at the end of the Flight
Readiness Review is that after all the elements have
presented, the chair, Mr. Readdy, will typically ask an
all-encompassing question. He'll scan the room, try to
make eye contact with everybody and say, "Is there
anybody in this room who has any information that has
not been brought forward that is relevant to making a
decision as to flight readiness?" It is rare at that
point in time that anybody raises their hand because
they should have done it -- and they do do it -- during
the element's previous presentation. Nevertheless,
Mr. Readdy makes sure he gives that last and final
opportunity for anybody to raise a hand and say, "Yeah,
there's something here that we haven't talked about
Also during the course of the
presentation, prior to this point in time, the elements
can take an exception to their Certificate of Flight
Readiness, which is basically a way of saying: I
certify that I did everything that's required by 8117,
also the appendix to 8117, which is my element-specific
requirements that I'm signing up to, and also the preamble to 8117 which applies to everybody equally. I
am signing up that I did everything and I've closed up
all the open issues in a closed-loop accounting fashion
with the exception of this one following issue; and
that's the Exception to the Certificate of Flight
A last thing we do at the Flight
Readiness Review is that Mr. Readdy will poll his board
members and contractors and they will have the
opportunity to say verbally if they certify to flight
readiness. Anybody who has taken an exception to
flight readiness will, in addition, at that point in
time, verbalize that exception, say something to the
nature of, "With the exception of issue of working with
shuttle main engine thermocouples" -- I'll just use
that as an example -- "we certify that we're ready to
go fly the next flight and, furthermore, we will not
allow the launch to proceed until we clear this
exception to the COFR." You're kind of a good lead-in
to the pre-launch MMT because that's going to be the
venue at which we clear the exceptions to the
Certificate of Flight Readiness, if you'd like me to
continue on into that at this time.
DR. LOGSDON: As you do that, can you
give me a sense of how often you get to a pre-launch MMT with significant open items?
COL. HALSELL: Exceptions? I would say
that -- I'm going to guess. We can go back and get the
exact percentage over the last couple of years, but it
is not unusual, somewhere between 25 and 50 percent of
the time, I would guess, that at least one exception to
the Certificate of Flight Readiness is presented, and
it's always presented with the conclusion of
Mr. Readdy, "We think we can or cannot clear this
exception in time to make the launch date that you're
considering and therefore we do or do not recommend
that you press forward toward that currently suggested
At that point after the flight readiness
poll and everybody's had a chance to say their piece --
and this might play in a little bit to the question
that Mr. Wallace had -- it is tradition that Mr. Readdy
adjourn to another smaller room with only invited
participants. Usually that's going to be the Flight
Readiness Review Board, the prime contractor CEOs, the
launch director, the manager for launch integration,
and a few other selected folks. In that smaller forum,
Mr. Readdy makes it clear that if there's anybody who
for whatever reason -- and I can't really understand
why -- but if there's anybody who wants to say anything there in that smaller forum that they were not willing
to come up with in the larger forum, now's the time and
place to do that, before we set a launch date. And it
is in addition to that information that's made
available to the associate administrator at that time
that he considers before he presses forward with
setting the launch date or not. We can and we do set
launch dates with exceptions to the Certificate of
Flight Readiness still pending, but only if he has firm
understanding and recommendations that we're going to
be able to clear them prior to that launch date.
If you like, I'll press forward with the
next couple of slides. So we've finished the Flight
Ready Review process. The members of the board have
been polled. We've adjourned. The associate
administrator has adjourned and had his opportunity to
hear anybody in private and also to decide if he wants
to set the launch date. For the purposes of this
illustration, we'll say the launch date was set and
that we do have some actions and an Exception to the
Certificate of Flight Readiness that have to be
accepted prior to going to fly.
Let's go ahead now to two days prior to
launch. Remember, the whole world came to the Kennedy
Space Center for the Flight Readiness Review. They now go away and do their business. Two days prior to
launch, we require once again that everybody come back
to the Kennedy Space Center. We do it two days prior
to launch because we want everybody to have a chance to
get back, get in place in plenty of time to set their
other job duties aside and to concentrate only on the
next safe and successful launch.
Two days prior to launch, we convene the
Mission Management Team. The Mission Management
Team -- and I believe if we could go to the next slide,
please -- I was thinking that I had a slide that showed
the composition of the Mission Management Team.
Basically if you go back to the FRR agenda slide,
remember all the participants, all the people who
participated in presenting the information to the
Flight Readiness Review associate administrator, those
organizations and their leaders now become the launch
integration manager's mission management team. It's
totally appropriate to think that we've not had our
review by the very senior level of NASA management and
they are now handing off to the mid-level management,
with their supervision, the job of launching this
vehicle safely within the constraints and within the
rules that have been set aside for us to work with
Columbia Accident Investigation Board Hearing
So that Mission Management Team convenes
and we go through basically the same agenda that we did
for the Flight Readiness Review. Every element, every
project gets the opportunity to present any interim
issues, anything that has arisen since the Flight
Readiness Review. If there are any exceptions to the
Certificate of Flight Readiness, the full and complete
rationale for that is presented there to the same level
of rigor that it would have been presented in the
Flight Readiness Review.
As the launch integration manager
chairing that pre-launch MMT, I felt it was important
that I get input verbally and visually and in public
from the program manager and from the associate
administrator at the MMT that they concurred on that
FRR COFR exception. In other words, it wasn't just the
middle managers now clearing something that previously
wasn't good enough for the senior managers to go with.
At the end of that MMT, we, once again, poll all the
participants to make sure that they are "go" to press
forward with the countdown.
From that point on, the Mission
Management Team is activated. I know where each of
them is. I can convene a meeting in literally an
hour's notice if I need to during the launch countdown. The next time we convene will be formally three hours
prior to launch, in the Launch Control Center.
If I can have the very last slide in the
whole package, I believe it's a picture of the Launch
Control Center. As he's scrolling forward -- at three
hours prior to launch, the Mission Management Team will
convene in this room that you see.
Next slide, please. Here's another view
of it. Up and in the dark to the upper left is where
the Mission Management Team resides. The larger room
is the Launch Control Team and the Launch Control
Center under the direction of the launch director, who
stands just about underneath that American flag in the
center of the room.
It can help you to understand the
relationships here as we go through the final hours of
the launch countdown. At this point, the Mission
Management Team has really done their job and we've
handed off responsibility for the successful launch of
the mission to the launch director who is directing the
Launch Control Team, as long as he or she is able to
work within the constraints of the Launch Commit
Criteria. That is huge, several-volume book which is
the what-if of every launch and represents the
corporate history of all the problems that we've either experienced or we've had the opportunity to think
through ahead of time that we might experience and our
reactive measures that we would take to further clarify
the problem and our ability to go launch safely.
For practically all the launch commit
criteria, when you run through the procedures, it ends
up in one or two branches. Either you have resolved
the issue as being safe to go fly, clear to launch or,
no, we're not sure, you have to stand down that day,
unless the Mission Management Team is offered rationale
which allows you to press forward and approves it in
real time. The Mission Management Team is there to
provide guidance if the launch director gets outside
the launch commit criteria and needs guidance.
GEN. DEAL: Jim, I just want to get back
to in-flight anomalies very quickly and get your
perspective because you experienced a very serious one
on STS 83 personally. What I want to do is get your
perspective on, following STS 83, how the process went,
did it underscore the strengths in the program, or were
there lessons learned by which we improved the
in-flight anomaly process following STS 83.
COL. HALSELL: Certainly I can lend my
experience from STS 83, and I think the question that
you're asking about the in-flight anomaly process is one of the reasons that we invited Bob Castle, as one
of the representatives of the in-flight MMT team, to
comment. So I'll hand off the remainder of that
question to him.
The issue you're talking about on STS 83
back in 1997 was that after we launched, we experienced
an in-flight anomaly concerning some out-of-family and
unacceptably divergent fuel cell substack delta volt
readings, which is a way of saying there were some
increased level of risk that if we were to continue the
mission with that fuel cell powered up that you could
experience crossover and that could lead to fire and/or
explosion. So that was deemed to be an unacceptable
risk. It was equally unacceptable to shut down and
save that fuel cell and continue the mission to nominal
conclusion on just the two remaining fuel cells. So
the Mission Management Team came to the conclusion that
the only safe and prudent thing to do was to have us
close up the lab, prepare to make an early entry back
home; and we did so after only four days in space.
The conclusion of that story is that
between then and STS 84 which, as I remember, wasn't
the very next but the one-after-the-one-after flight,
on STS 94, they resolved that particular issue, they
understood it after they were able to get the fuel cell and do all the testing back at the vendor to understand
that, in fact, it had most likely been an indication
problem, not an actual issue, and that we could have
stayed up on orbit. But there was no way to have known
that in real time and I, certainly as the recipient of
the safest course of action, I appreciate the action
that the MMT took at that time. So I think that is an
example of how, when faced with extremely difficult
choices, expensive choices both in terms of money, in
terms of the manifest having to be replanned for
probably several years downstream, but still when
confronted with that highly undesirable set of
consequences for making the safe decision, the on-orbit
Mission Management Team did make that decision. They
brought us home and we re-flew that mission a couple of
flights later with a full measure of success.
ADM. GEHMAN: Okay. Let's let Mr. Castle
give his introductory remarks, and we can always ask
MR. CASTLE: Okay. Well, that does lead
into what I was going to start talking about a little
bit. I don't have any charts. So you can feel free to
interrupt me even more freely than you have already.
As far as the way the realtime team goes,
we pick up the launch. Right after liftoff is when the realtime team picks up and starts conducting the
flight. I would call flight director the mid-level
management team that Jim referred to.
The flight director also has his set of
requirements. The specific ones that come to mind are
the flight rules and the SODB, which is the Shuttle
Operational Data Book. The flight rules is a large
book. I didn't bring one around. It's about yea thick
for the space shuttle. It's what I call pre-made
decisions, decisions you've already done your
what-if'ing and you've thought about them and you've
thought about the situations and the cases very
carefully and you write down what it is that you're
going to do for each of these particular cases.
In the one that Jim mentioned, the loss
of one fuel cell, it says you need to land what's
called a minimum duration flight to minimize the length
of time we stay in orbit because if you lose another
fuel cell, you can land with only one fuel cell but the
power-down you have to get into is dramatic and it
impacts your avionics in lots of other ways. So we've
already gone through that debate. If we lose one fuel
cell, we're going to land and we're going to cut the
flight short, early.
The MMT got involved with his flight because it wasn't really clear from the indications
whether we really had a bad fuel cell or not. So
that's where we had to call the engineering guys
together to look at that. But if it's clear we've lost
a fuel cell, the flight control team doesn't have to
consult anyone. We'd say, okay, the flight rules say
go do this, so this is what we're going to go do.
The SODB is the Shuttle Operational Data
Book. That is another book that is maintained by the
space shuttle program. It's a list of how you operate
the shuttle. You can operate the shuttle with the
temperatures on this loop, greater than this and below
that. This type of information. Kind of like an
owner's manual for your car except, again, it's several
volumes. It's fairly thick.
The flight rules are controlled by the
shuttle program. The final version of all of them are
taken forward to the PRCBs for approval. There are
several lower-level boards chartered by the program
that manage those rules.
People have asked about the safety
process. Any changes to the rules, that's done on
what's called a CR form, a change request. The Safety
folks review those as well, as all the rest of the
disciplines -- engineering, program offices, space and life sciences, FCOD, MOD, all the different areas.
There is a mid-level board, what's called the Flight
Rules Control Board, which is chaired right now by one
the deputy chiefs of the Flight Director Office.
Again, all of those same organizations represented and
then their approved set of rules come forward in a
change package to the PRCB for final approval by the
program. A very similar process used for the SODB, the
way it's managed.
So those are two things that I start off
with as my requirements, if you will. There are a
couple of other things that are like the flight
requirements document which are a mission-specific
document. Okay. The other two I just mentioned,
that's how you operate the orbiter, how you fly. The
FRD says, well, here's what we want you to go do. We
want you to conduct a space lab mission. Here's how
long we want you to stay in orbit. Here are the
priorities of things we'd like you to do. That type of
There is also a much smaller book of
flight rules that are flight specific. In that again,
you're writing down rules, mainly a priority list,
rules that are specific to the payload or the
particular operation you have on that flight. Those are flight specific. Also approved by a very similar
process and finally approved by the shuttle program
manager at the PRCB.
Also I want to say that the flight rules
are things that when we train people, we take these
things very, very seriously. The simulation folks try
to put in failures and various scenarios that will
stress people's thinking. Okay? They'll break a piece
of instrumentation someplace in the simulator. Well,
do people recognize what's just failed? Do they
recognize the instrumentation they've lost? Do they
understand the implications to the flight rules? Have
you just had a flight rule violation because of this
failure? Sometimes just loss of instrumentation is no
big deal. Sometimes you really have a rule violation
because we've thought through if I don't have this
measurement, then this thing that's really bad can
happen to me and there's nothing I can really do to
detect it or I've actually impacted the safety of the
vehicle because I can't measure something. Sometimes
Each rule is also annotated. Let me back
Jim talked about the top-down hazard
process and the bottoms-up failure modes and effects process. Anytime that this hazard control process says
we need to control this hazard by a certain operational
constraint, we want you to always flip this switch
before you flip that switch, a flight rule gets written
that says always do it in this order. That flight rule
gets annotated that it's a hazard control. So anybody
reading the rule book knows that this is a control for
a hazard that's been identified for the program. That
does a couple of things. The main thing it does for
you is when somebody comes along and says I'd like to
change this rule for whatever reason, it's in black and
white, right in front of you, that you've got to run
this by the safety community, you've got to look at it
carefully, look up that hazard control, make sure
you're not undoing what we carefully did.
They're also flagged from the bottoms-up
review. Anybody in the bottom-up review that comes up
with a classification of either a Crit 1, 1R, 1S,
and 2, I believe, gets classified on a Critical Items
List or a CIL. So we flag those rules, as well. It
says, okay, this rule is part of the rationale for
saying this critical item is acceptable. Again, you
get the same type of things that are controlled
operationally. If you have Failure A, then you must
take this following action to make sure another problem doesn't sneak up on you.
Everybody works really hard to understand
those, even though the book is very, very thick. We
train them very, very heavily. Our simulation guys are
very sneaky. They will put in an instrumentation
failure here and a power system failure there and an
avionics box failure here and you've got to realize
that when you add all those three things up, you've
really got a much more serious problem than it seems
like. Generally they'll set us up that you need to
recognize, hey, one more failure could really be bad.
So we work that very, very hard.
Again, I'm just going to keep talking
until somebody wants to stop and ask me questions.
Let's see. The basic rule, again, is the flight rules
and the SODB -- when I say the realtime team, let me
talk a little bit more about who the realtime team is.
There is the Flight Control Team, which is led by the
flight director who sits in the middle of the room. I
don't have a picture, but you've seen the room. There
are flight directors there 24 hours a day during a
We also appoint a lead flight director
who is appointed generally at least on the order of a
year before the mission. They oversee not only the mission but all the launch preparation, all the
preparation times, all the crew training, everything
else that goes on for that prior year. That includes
the little first chart that Jim put up, all the little
boxes. Either the flight director or some member of
his team plays in every one of those boxes throughout
the preflight process.
There are other members of what I call
the flight control or the realtime team. A very
important team is the MER, the Mission Evaluation Room.
That is a room that's down on the first floor of
Building 30. It is run by the program office and is
staffed mainly by people out of engineering and various
contractor support -- Boeing, various subsystem
contractors. Their function is evaluation. They watch
what's going on on the vehicle. They look for more
shuttle trends, things aren't clear black and white but
maybe more subtle problems. If there is a problem, of
course, they're ready to be activated, ready to go work
any details. Things are never quite as crisp and clean
as they look like in simulation. So you always like to
have the engineering talent there, ready to go. That
group in the MER includes a safety console position,
again, always watching what's going on as we operate
the mission, understanding all the hazard controls and all the things that have been preflight analyzed.
There's another room in the building
which is called the Customer Support Room and that is a
program office room. Representatives who report
directly to the program manager staff that room
hours a day. Again, they're watching out for
programmatic requirements. They're there to be
consulted. If we get into a situation where I can't do
what their priority list says I need to do, they're
there to go rework that. "Okay. This just happened.
I can't do your No. 3 item on the priority list. What
would you like to do? What options would you like to
invoke?" So they're there 24 hours a day, 7 days a
week during the mission, ready for consultation; and
they pay attention pretty well.
There's a formal CHIT system. It's
called a CHIT. I don't know what CHIT stands for, but
there's a formal paperwork system where if we make a
request for information or a request for special
analysis, we write down exactly what we want. It is
coordinated through the appropriate person who we're
requesting this of. Anyone in the building can write
such a CHIT. It comes down with an answer, and we
don't close that CHIT until the originator agrees that
whatever they wanted done has been done and done correctly. Again, it's a very formal process, I think,
that works fairly well.
ADM. GEHMAN: Let me interrupt. To carry
over the discussion, I asked a hypothetical question,
as did Dr. Logsdon, that if Columbia had returned
safely from this mission, we still would have an IFA of
a major foam strike.
MR. CASTLE: We would. It's interesting.
People have talked about it from the flight director's
perspective. That's one that would come in through the
program office and not the realtime team, because the
realtime team didn't know the foam came off the tank.
It was only the photo analysis folks the next day who
came in through the MER who knew something had come
from the tank. During the realtime ascent, I'm pretty
sure the team didn't know anything about it.
ADM. GEHMAN: That's right. But a day
later or a day and a half later, whenever the photo
analysis of the ascent, the launch photography was made
available and the MER was informed that there was a
strike, is it formally classified as an IFA at that
time or does it take more paper and more meetings or
something like that? I'm thinking MMT now. Are
members of the MMT or the flight team, are they aware
now that we have something to deal with?
MR. CASTLE: Yes. As soon it came
through the MER, it should be made known to the next
MMT, whenever that was. MMTs like generally every two
or three days. Now, I'm going to have to talk
generically here because I had really very little to do
with STS 107. I was there for a tiny period of time.
ADM. GEHMAN: That's perfectly all right.
MR. CASTLE: The realtime team, we
probably would hear about it from the MER even before
it came to the MMT. I say probably because we talk to
those guys a lot. We play in their games a lot.
ADM. GEHMAN: Since damage to TPS is a
Crit 1 issue, if you had debris striking the TPS and
the system was aware of it, I mean, both the flight
directors and the MMT personnel, they use the same
rules and the same categories and the same processes.
MR. CASTLE: Yes, we do. Sometimes the
in-flight anomaly list or the funny list will vary.
The flight control team may have different items on
their list than the MER has on their list and the CSR
has on theirs, which I think is a healthy thing. You
get together and decide which ones you want to carry
forward on a formal programmatic level.
ADM. GEHMAN: You mentioned that loss of
one of the fuel cells is in the flight rules.
MR. CASTLE: Yes, it is.
ADM. GEHMAN: What about damage to TPS?
Is there a flight rule for damage to TPS?
MR. CASTLE: I would have to go look it
up. I don't think there is one, mainly because I'm not
sure what the flight control team could do about it, is
the real gotcha there. If you knew exactly where it
was, then maybe you could do a little something about
it. But if there are any rules, they just tend to go
ADM. GEHMAN: So if it's outside the
flight rules, then it would be kicked up to the MMT.
MR. CASTLE: I think it's kicked up to
the MMT, yes.
ADM. GEHMAN: Correct me if I didn't get
this right. Did you say that changes to the flight
rules are approved by the PRCB?
MR. CASTLE: Yes, they are. All changes
to the generic rules are approved up at the PRCB level.
We don't take individual changes. What we do is we
process individual changes at the Flight Rules Control
Board, which is one board down. Then when we collect
up enough that we need to make an actual page change to
the book, we bring that forward to the PRCB.
There is a realtime flight rule change process that is in place where the flight director or
the mission ops representative, the representative of
essentially my boss, John Harpold. Those can be signed
off by the flight director or by the mission ops
representative; and the actual process allows it to
happen without the MMT. That is there so that if
there's no time to go have an MMT meeting, you can go
do what needs to be done. As a matter of practice, I
don't think any of them have ever been signed off
without being fully briefed to the MMT; and the number
of realtime changes is very, very small.
ADM. GEHMAN: Okay.
MR. WALLACE: Can you give a rough sort
of breakdown of the MER in terms of contractor versus
civil servant size?
MR. CASTLE: I really don't think I can
give a good breakdown because I don't really know. We
operate very much badgeless, is the term I like to use
around here. Even on the flight control team, the
people that I know, I'll tell you their names and their
wife's name but I can't tell you whether they're a
contractor or a civil servant because it's not really
important. So I really don't know about the MER. In
the flight control world, simply because I've seen
other statistics, it's about 30 percent civil servant and about 70 percent contractor.
MR. WALLACE: So when you say that anyone
can write a CHIT, then that includes contractors can
MR. CASTLE: A contractor write a CHIT.
They bring it to the MER manager for forwarding on into
MR. WALLACE: Does the CHIT guarantee a
certain level of elevation, and what would that be?
MR. CASTLE: Well, it guarantees that it
goes through a controlled process. They can write a
CHIT. So, for example, someone in the MER could write
a CHIT to the flight control team saying I would like
to go do this or I'd like this particular information
retrieved from the vehicle via a data dump or
something. It's guaranteed to go to the MER manager;
and if the flight control teams has to do anything,
then, of course, the flight director will hear about
it. That could be as far as it goes and the CHIT gets
MR. WALLACE: Does the CHIT go to the MMT
in an appropriate case, or is the CHIT something that's
with the flight control team?
MR. CASTLE: It's within the flight
control team, the CSR and the MER. It could certainly go to the MMT if either the missions ops rep or the MER
manager or the CSR reps wanted to elevate it to that
point as an issue, but CHITs routinely do not go to the
MR. WALLACE: Generally, could you
describe the sort of level of contact, day to day,
between the MER members and the realtime flight team?
MR. CASTLE: Fairly routine contact.
Generally, at the system level an electrical power guy
will talk to the EGIL electrical power guy on the
flight control team probably on a daily or
shift-by-shift basis. They will talk to each other on
voice loops and just say, "How are things going? Were
you working anything?" I know they did that back when
I worked in that level. At the flight director level,
probably daily we talk to the MER managers to see
what's going on, or they will talk to us.
MR. WALLACE: Is there a process at shift
change, sort of a formal tag-up process, or is that by
MR. CASTLE: There's a formal shift
change of the flight control team where we hand over to
each other. It's all done on a voice loop where we go
around the room: "What are the issues that you're
working?" The MER is certainly available to listen to those loops, and I know from experience that they often
do. MER is not usually, as an entity, polled during
the handover for shuttles. Last time I did the shuttle
flight was a couple of years ago. Now, on the station
program, we do poll the MER if they're there. They're
not there nearly as often.
MR. WALLACE: I have heard it said that
typically the MMT might become involved in a decision
if it's sort of outside the book, outside your flight
MR. CASTLE: Yes, that is by definition.
I look at the flight rules in a couple of ways. It is
pre-compiled list of decisions that have been agreed
upon. It's also what I consider kind of my contract
with the program manager. If it's inside this book,
then he's already agreed that this is something that's
appropriate for me to do with the vehicle that really
is his responsibility. I'm being delegated it during
the flight. So if it's inside the rules, then that's
perfectly my right or the flight director's right to go
operate within the rules, within whatever the program
has laid out. If it's outside the rules, it needs to
go to the MMT. It needs to go to the MMT for approval
of whatever I'm about to do, if there is time. There
is a caveat, again, since you're flying, if there's not time, the flight director and the mission commander do
what they think needs to be done. If there's time to
consult the MMT, then by all means you do and you get
your approval before you press forward.
MR. WALLACE: Would the sort of realtime
flight team expect to be aware of most anything going
on between the MER and the MMT as a general practice?
MR. CASTLE: As a general fact, yes. We
have a representative to the mission. We call him the
MOD. It's really, again, a representative of my boss,
being the director of MOD, who attends all the
MER meetings, all the MMT meetings. So anything that
goes on in that meeting, the realtime team has a
representative there who comes back and consults, talks
with the flight director. So the flight director will
be aware of anything that's going on in the MMT; and
like I say, we not only come back and talk about that,
the rep comes back and writes a little short report:
Here's what got discussed; here's what the flight team
needs to know about what's going on in the MMT.
DR. RIDE: You said that there are no
flight rules that cover tile damage.
MR. CASTLE: I can't remember any off the
top of my head. I'd have to go look it up.
DR. RIDE: I'm curious whether that would have been a conscious decision by the program. I know
the flight rules are reviewed periodically. They are
really the bible that the flight team uses to operate.
So I would have thought that at some point someone
would have brought up should we have a flight rule on
tile damage. So I'm curious about what the discussion
around that would have been and why there isn't one.
MR. CASTLE: I remember some of that from
quite a few years ago. Again, a flight rule is a
decision, is the way I like to look at. It's a
decision that's been made. So it should be, if you
know you have tile damage, then you go do this. If you
don't know what to do and there's nothing you can do
differently, then there's no point in having a rule.
So to my knowledge, we've never had an answer to what
you do if you have tile damage, because there's nothing
we can do in real time to do much with trajectories or
anything else that I'm aware of that would make any
DR. RIDE: Let me ask maybe just a little
bit of a different way. You know, suppose we're back
in time and 107 is in orbit and the crew happens to
look out and sees damage to the left wing. Then it
would have been reported, essentially, into the flight
control team. I just wonder whether you could describe how that situation might have been handled and whether
it would have been handled differently, whether the
assessment would have been handled differently or
whether the flight control team's involvement would
have been different than it was.
MR. CASTLE: How it would have been
handled, the flight control team would have immediately
reported that up the chain because we're going to need
more resources than the realtime flight control team
has to do anything about it. I'm sure we would have
turned on all sorts of effort in the mission evaluation
room to look at possible repair. The trajectory guys
would get turned on yet again to go look at is there
any other way, anything we can do to fly the vehicle
differently because of the specific damage that we see.
We would have worked on it very, very hard. I'm sure
we would have pulled out all the stops to try and do
anything about it; but, again, there are no flights
rules on it right now because, as Jim talked about in
the very beginning, there are three areas that are
simply Crit 1. If they fail, there's nothing you can
do about them. Thermal is one. We do not have a
flight rule on structural damage either. If you found
a broken member someplace, there's no flight rule that
says what to do about that. Pressure vessels -- actually we do have flight rules on that. Because if
you have a leak, you know, you can take action before
whatever it is all leaks out. But structure and TPS,
there really aren't any rules on that. But, yes, if we
had known about it, we would have pulled out all the
stops and done everything we could to find the answer,
I'm sure. The realtime team would not have been able
to do much but implement whatever somebody else figured
ADM. GEHMAN: Mr. Castle, is your
reporting chain to the center director?
MR. CASTLE: My reporting chain, yes, is
to the center director.
ADM. GEHMAN: I mean, I understand under
the flight rules and when you're flying, you're working
as an agent of the program manager; but your reporting
chain is to the center director.
MR. CASTLE: Yes, my reporting chain is
to the director of MOD who reports to the center
ADM. GEHMAN: I don't know whether or not
the slide presentation that Colonel Halsell put up
there is retrievable or not. I don't even know where
they come from. Could we have Slide No. 12? Let's go
back to Slide No. 12, which is the FRR agenda. What does the S&MA organization say when it's his turn to
MR. CASTLE: He talks about any program
safety paper that is open or any hazards that are open,
need to be closed, any new hazards that have recently
come into play, even if they've been safely controlled,
that type of thing. He gives a report on that and are
there any things in the safety reporting system, this
anonymous safety reporting system that's been set up,
are there any of those that are out there that affect
this mission. He talks about and reports on all those
COL. HALSELL: In addition, the safety
community, prior to the Flight Readiness Review, has
their own pre-FRR review. I believe they call it the
PAR. Really that stands for Prelaunch Assessment
Review. That's done by all the elements in the project
safety organization reporting up to Code Q, which is
Bryan O'Conner at headquarters, in association with the
Johnson Space Center safety space shuttle division.
All of these elements come together to review all the
issues. In addition, if there have been any increases
in hazards -- and I wasn't taking good notes -- but all
of the elements that we've talked about that the safety
organization is responsible for being the look over our shoulder to make sure that we're doing our closed-loop
accounting system. They report that there. Once
again, they report it in the affirmative and also the
negative. It's not good enough that they say we don't
know of anything; they come forward and say we looked
and we did not find anything. In the degree to which
it's not possible for them to stand up and say that,
then we have an exception to the Certification for
GEN. HESS: Let me talk about the MER
just a second. I really have a simple question.
During the course of the mission, the MER works for
MR. CASTLE: The MER works for the MMT.
GEN. HESS: Now, do you have any direct
authority, as the flight director, over the MER?
MR. CASTLE: In general, I can ask them
to go work on things. I can send them CHITs asking for
things. Do they absolutely have to do what I tell them
to do? No, they don't; but, in general, I think it's
been rare that if a flight director really wants
something with good rationale that they don't jump in
and do their best.
GEN. HESS: That's a good lead-in to my
other question here. We've heard a lot of characterizations about the preflight FRR process and
then the on-mission process that goes; and some would
say that one part, the pre-launch part is very, very
formal but then it tends toward being a little bit less
structured and less formal because you have this book
of rules and so the communication is decidedly
different. How would you respond to that?
MR. CASTLE: I think it is a little less
formal during the flight, for a couple of reasons.
One, I think since things are moving much more rapidly,
I think it needs to be a little less formal. I think
we also, unlike the previous meetings and all the other
work in the offices, everything that the flight control
team and the MER team does with each other, they do it
on voice loops. All of that is recorded so we've got
records of everything that's happened. We can go back
and sort out exactly what's happened. Things do need
to move a little faster when you're flying than when
you're sitting on the ground deciding whether you
should fly or not. And that's what's built in to allow
more flexibility and a little more speed in making
decisions. We try to have everybody in the building on
a voice loop who has got a stake in the situation and
can listen and participate in making the decision right
then. The MER manager is listening to what the flight director is talking about doing on the flight loop. In
my experience, those people have a remarkable lack of
shyness. If they feel they need to stand up and be
heard from, they will stand up and be heard from. Is
it as formal with normal paperwork going back and forth
and signatures and all of that? Yes, it is less
formal, considerably less formal in that perspective.
GEN. HESS: Following on with that, we
all have in the back of our mind this perhaps Hollywood
picture of Apollo 13 and, you know, failure is not an
answer and the flight director was the center of
gravity in running that particular event, but what
you're describing today is that if it's something
that's outside the bounds of the flight rules, it's not
the flight director that's the center of gravity, it's
MR. CASTLE: The MMT is the center of
gravity for making all the decisions and deciding which
way to go, yes. In terms of actively solving a
technical problem, I think you'll find the MER and the
flight director are the ones most involved in trying to
come up with a solution to a technical problem.
I was not in NASA for Apollo 13. I'm not
quite old enough for that, but I do know quite a few
folks who were here in that time frame. The movie, as all movies do, simplified things. There were a lot
more people involved in working on Apollo 13 than the
few that you see on the movie. There was a huge number
of people in both the MER and the flight control team
that did a huge amount of work, pulling all those
GEN. HESS: So then would your
expectation as a flight director be that, in the case
of 107 where we had the debris strike we know about and
then the visual debrief of the ascent video showed this
debris and the engineers were beginning to work and
decide whether or not that there was a problem with the
orbiter, that the CHIT system and the request for
information would have led to a filling in some of the
blanks that the engineers were obviously after?
MR. CASTLE: I don't know if it would
have or not. Again, I was not working 107 specifically
during the orbit phase.
GEN. HESS: I'm just talking about
normally. I mean, if you had been, would you expect
that process to formalize itself and get into a formal
CHIT if the engineers wanted information.
MR. CASTLE: If they wanted information
that they felt we could provide, I would expect them to
write a CHIT; but again, if they know we can't do anything or know we can't provide the information, they
don't spend their time writing a CHIT for it. If they
thought we could get it, I would have expected them to
MR. HUBBARD: One question about who's
"in" box problems end up. You described a very
rigorous process with a lot of opportunities for people
to speak up and simulations that involve all manner of
different processes, things that could go wrong and the
evil simulator sitting back there failing things on you
and so forth. So that captures a way of doing business
that encompasses a whole great raft of problems.
Now, looking at the other side, you have
damage to the thermal protection system tiles, every
single flight. You know, something greater than
divots, greater than an inch and more than a hundred
total; yet TPS is a Critical 1. It's one of the
handful of three things for which is there not a
fail-safe and there's no flight rules probably on this.
So that problem, whose "in" box does that kind of
conundrum, that problem end up in?
COL. HALSELL: We'll tag team this one.
The short answer is that it's the space shuttle program
manager's job to organize the appropriate response to
any and all issues when it comes to making the final determination if we can recommend to the associate
administrator that we're ready to go fly safely. So if
Ron Dittemore were sitting here in front of me, he
would he say, "It's my 'in' box" because he's the one
who controls the resources and the application of those
resources; but at a personal level, I think each and
every one of us involved in any way, shape, or form
with -- touching the particular example you're talking
about here, the TPS, a lot of people have
responsibilities which touch upon that, whether it's
myself as a launch integration manager and that means
that last year the person who runs the interagency
imagery working group, the people who took the imagery
that first revealed this issue to us, for example, that
person reported to me. So that's one area that I'm
involved, one of many; or if it's systems integration,
the people responsible for grabbing hold of these
issues -- and this would be a perfect example of where
what one element in project over here is doing or not
doing may or may not impact another element over here
and we need to make sure we're never guilty of not
communicating back and forth. And it's the systems
integration group which is responsible of being the
accountability hounds to make sure that that kind of
conversation takes place. And then you get down to the
elements themselves. External tank, if they're
shedding foam, it's got to be their primary
responsibility for understanding that issue and then
dealing with it. If it's the orbiter vehicle who has
an issue with the environment within which their
thermal protection system is being asked to operate,
then they are equally accountable for raising their
hand and making sure those issues are brought forward.
You can say that the solid rocket booster element could
possibly either be the source or recipient of debris
also. So everybody has a responsibility in this area,
and it all goes uphill to the man who's in charge.
ADM. GEHMAN: Well, gentlemen, Mr. Castle
and Colonel Halsell, thank you very much for your very,
very forthcoming and complete and responsive testimony
today. It's very helpful to us. We agree with your
opening statements that we're all here for the same
reason, to find out what happened to STS 107 and to
recommend measures to prevent it from ever happening
again. So we all have the same goal here.
You've been very responsive, and your
answers have been very complete. We appreciate your
patience, and we're going to take a short ten-minute
break while we seat the next panel.
Thank you very much.
ADM. GEHMAN: All right. Board, if we're
ready, we'll resume. I'll ask the people in the room
to please take your seats and be quiet, please, so we
can get back to work.
The second half of the afternoon public
hearing will be looking more specifically at foam
events and debris events. We have with us Mr. Scott
Sparks, who is the department lead for external tank
issues, and Mr. Lee Foster -- both, I believe, from
Marshall, if I'm not mistaken.
THE WITNESS: Right.
ADM. GEHMAN: Before we start, gentlemen,
I would ask you to affirm that the information you
provide to the board today will be accurate and
complete, to the best of your current knowledge and
THE WITNESSES: I will.
ADM. GEHMAN: Thank you very much. Would
you please introduce yourselves and tell us a little
bit about your background and what your current duties
LEE FOSTER and SCOTT SPARKS
testified as follows:
MR. FOSTER: My name is Lee Foster. I've
been at the Marshall Space Flight Center for over
years. Currently I'm with the Space Transportation
Directorate. I'm an old technical guy. I've spent
many years working aerodynamic design and aerothermal
design of the Marshall space shuttle elements, and I've
been involved with the aerothermal testing of the TPS.
Currently to the external tank I'm kind of a gray beard
that they call on occasion.
ADM. GEHMAN: Thank you very much.
MR. SPARKS: Scotty Sparks. Academic
background, a Bachelor's in chemistry, Master's in
polymer chemistry. I have been employed with NASA
since '89. I been working external tanks since '91. I
have worked other composite cryo tankage issues. Just
recently I mainly have specialized in the areas of cryo
ADM. GEHMAN: Thank you very much. We're
ready for you to begin. If you have a presentation for
us and whichever one of you is first, go ahead.
MR. SPARKS: Let's go ahead and get the
first chart up and we'll start, hopefully.
ADM. GEHMAN: We have copies of your presentation. Let's go ahead, and they'll catch up
with us when the electrons do.
MR. SPARKS: The objectives that Lee and
I want to discuss would include cryoinsulation's
purposes and its characteristics in the external tank,
material development and qualification, flight
environments, debris history, and some past issues,
some efforts, to try to tell about our efforts to
reduce debris, and also some recent observances.
ADM. GEHMAN: If you could go through
quickly the first two or three. We're really
interested in the environment and debris history and
efforts to reduce debris. Please proceed.
MR. SPARKS: The purpose of
cryoinsulation. The main purpose of cryoinsulation
pre-launch is to minimize ice formation, but it also
maintains the oxygen and hydrogen boil-off rates to
acceptable levels. We try to eliminate cryopumping
totally and we also try to densify propellant so we can
get the maximum mass per the finite volume that we
have. Upon ascent, we have to protect the tank from
aerodynamic heating as well as plume-induced heating.
We minimize effects on the structure of aerodynamic
loading, static loads, unsteady aerodynamic load.
Also, upon re-entry, we have to maintain a certain breakup altitude window to make sure it doesn't break
up too early to scatter some debris over a large area
or too late to scatter larger pieces of debris.
ADM. GEHMAN: My understanding is in
pre-launch, even if ice formation were not a problem,
you still would want to insulate in order to slow down
the rate of heating of the liquid hydrogen and liquid
MR. SPARKS: That's correct. There would
have to be some level of insulation to control that.
ADM. GEHMAN: When you say you try to
eliminate cryopumping, are you going to tell us what
that is or later?
MR. SPARKS: We will tell you about that.
ADM. GEHMAN: All right.
MR. WALLACE: Mr. Sparks, in following
the board's tradition of never letting anybody get
through their briefing, can you give just a general
sense in terms of the bipod, the whole bipod insulation
structure, as to its purpose as between pre-launch,
ascent, and reentry? I mean, does it really have an
important purpose particularly as regarding re-entry?
MR. SPARKS: Upon re-entry? No, it does
MR. WALLACE: Using this page of criteria -- pre-launch, ascent, and re-entry -- could
you sort of speak to the relative importance of those
MR. SPARKS: Sure. Upon pre-launch you
are going to get some level of possible ice formation
in that area, and that's one reason why we do have some
cryoinsulation in that area. There is some level of
rotation that that structure has to go through. So
there is some small areas that do not contain
cryoinsulation. That's the reason why we have the
heater inserted into that bipod to try the minimize
that frosting or that ice formation in that area.
As far as ascent, Lee, you might want to
talk ascent. There's not an appreciable amount of
loading in that area, but you might want to talk to
MR. FOSTER: It's a very complex flow
field in that region, which we'll go over in a few
charts. We have a ramp on our bipod to lessen the
aerodynamic loading on there. So all the TPS works for
the ascent part. It's a very massive piece of
structure, the bipod fitting itself, and the structure
it's on. So during the re-entry part of this, there's
really no effect.
MR. SPARKS: Going to the next chart, please. One of the questions we are often asked is why
don't you just fly one type of cryoinsulation. We're
currently flying four types of foams on there, and it's
driven mainly because we've got different environments
for different locations of the tank.
In the areas where we don't have high
heating, we'll be flying a polyurethane foam; and the
two types of polyurethanes are the BX-250 and a
PDL-1034. And on the LOx tank, we'll fly a
polyisocyanurate material, which is a little bit higher
heat-resistant material; and that's the NCFI series,
the 24-124 materials. The thicknesses vary upon the
tank also, but the thicknesses are driven primarily to
minimize ice formation and if there is additional
thickness required because of re-entry, then that's
added there upon that design.
Next chart, please. Me personally when
I'm working a foam issue, I like to think of the issue
in four terms as far as structure when it comes to
working a foam issue. First is a polymeric structure,
and very quickly this is a polyurethane or a modified
polyurethane, polyisocyanurate materials that we're
talking about. That forms the basic backbone of the
polymer and generally determines the strength of the
material. It also determines the strain capability at cryogenic temperatures. Polyurethanes are extremely
compliant at cryogenic temperatures, and that's the
reason why we use these materials. There are very few
materials that can take that strain.
The next level of structure would be
cellular structure. Generally, it's very important to
at least understand your cellular structure. We'll
look at a few pictures here. As you see the sort of
semi sort of random behavior of those cells, certainly
they are important in that some of your thermal
insulation characteristics are driven by your cell
Knitline geometry. This material likes
to be sprayed in fairly thin passes. In other words,
if you spray it very, very thick, all at one time, it
tends to pull away from itself upon cure and forms
stresses. So it is better to spray in passes. So what
that does is once you spray a pass, it skins over on
itself and the subsequent pass forms what's called a
There in that bottom picture is
radiograph of some materials that have been sprayed on
to a substrate. That's complex geometry in the
intertank region. That's a rib geometry. But the
radiograph magnifies the appearance of the knitlines, just to show that feature.
The strength can change due to that
knitline structure. In the region of concern that
we've been talking about the past few weeks, the bipod
area, especially when you manually spray an area, it's
very hard to determine from part to part an organized
or a specific structure as far as the knitline
geometry. On the automated sprays, the barrel sprays
on both the LOx tank and the hydrogen tank, you have
more of an order to those knitlines.
Finally, geometry. A flat panel with
foam on it, that foam's going to react differently if
that is sprayed upon, say, just a rib geometry, for
example. We found in some in-flight anomalies a couple
of years ago taken on a thrust panel that that material
would perform nominally on a flat panel but when
applied to a ribbed situation that the expansion
coefficient pushed up and the stress became great at
the tops of the ribs and contributed at least to the
loss of that material in that area. If that had been
on a flat substrate, that effect probably would not
have been demonstrated.
Next chart. Again, here's some
photographs of some foam blown up. You can see in this
picture here the story is mainly the cell structure. You can see the semi sort of random structure, what I
call the football nature. The rise direction is going
vertically, and you can see that it is preferential to
rise direction. You can also see the bar there, being
0 microns, and the picture just a little bit lower is
0 microns. It's the same photograph blown up.
Fairly small cells. That is one of the key elements of
this foam is that it's close cell and that it does have
a very low thermal conductivity gas in those cells.
What you're looking at are struts that
form on the outside of the cell in what I would call
windows that maintain that gas in that cell. Again,
polyurethane is a very compliant material. Also foams,
all of us here are sitting on polyurethane foams right
now that's just not a rigid foam. The chemistry of
that material is just a little bit different to make it
flexible. So it's a very compliant material if
formulated in that fashion.
Knitlines. You kind of have to look
closely there to see that knitline, and that's a
00-micron bar. So knitlines can vary in thickness,
depending upon the spraying conditions and also the
time allowed before you spray the next pass. That was
just a picture to show you how thin a knitline can be
and also how it is knitted, more or less a continuous polymer running through that area.
By the way, this is material that has
been pulled off just recently from the ET120 dissection
that we're doing out at Michoud. This is just a random
anomaly that I picked out of the laboratory and showed.
We have rollover phenomena; and that phenomena occurs
generally when you have, I guess, a complex geometry
underneath it that you're spraying. The rollover, when
you spray foam, it will push up on itself and start to
rise; and if you have a complex geometry, it won't fold
over on itself, much like a wave in the ocean will fold
over on itself and it forms a small void.
Can we hyperlink that? Can we show that
Talking about the relative hardness of
the material. This is going at approximately 700 feet
per second, which is visco-elastically. You see the
foam. That's a 3-inch piece of foam, about an inch in
diameter. BX-250, the material used in the bipod.
If you can click that again and show that
again, please. Maybe it has to quit before you click
Undoubtedly, you see the flexibility of
those struts and that material able to absorb that
energy, and then finally the shock wave does break it apart. We haven't looked at those materials yet or at
least I haven't seen the analysis, the electron
micrographs of those materials, but we're going to look
at that and I conjecture that those windows in that
cell that we're looking at are probably burst but the
struts may be somewhat maintained. So the material
looked like it was still holding together somewhat,
even though the pressure in the cells probably were
That was a load cell. I think that was a
steel load cell. They were trying to understand the
amount of energy in that material.
MR. HUBBARD: Two questions here. When
it says chilled, how cold is that?
MR. SPARKS: I believe they submerged in
liquid nitrogen and it was a best effort to take the
foam bullet, put it in a sabot, and then fire. I
believe it was around --
MR. FOSTER: Minus 38 degrees or
something. It was only chilled. It wasn't cryogenic
MR. HUBBARD: C or F?
MR. SPARKS: F.
MR. HUBBARD: I mean, minus 38 --
MR. SPARKS: Fahrenheit.
Okay. Go back, please.
MR. HUBBARD: And the little stripes in
what looked like five segments along your column there,
are you highlighting the knitlines, or is that
MR. SPARKS: That was half-inch
gradations, just showing that was a half inch.
MR. HUBBARD: Oh, to see the compression.
MR. SPARKS: Correct.
Next chart please. Very quickly, this is
a top-level chemistry view. One of the things that
we're talking about is polyurethanes in the form of
BX-250. On the side wall we're talking about NCFI
materials; and that's a polyisocyanurate, which is a
modified polyurethane. The difference between the
materials generally can be explained here. You have a
general polyurethane reaction occurring between a
diisocyanate polyol. It forms a very flexible urethane
On the lower half of the chart, it
describes the first reaction for the polyisocyanurate.
It's a trimerization reaction that then undergoes
urethane reaction with its R components. It's a little
bit more ring structured which forges a little bit
higher heat resistance. This comes into play when we look at processing conditions. One of the reasons why
we use polyurethanes in some locations is that we can
spray it out on a floor because the substrate does not
have to be heated. For polyisocyanurate processing,
the substrate has to be heated. One of the reasons why
is because this reaction here is a little bit slow in
kicking in. So you have to give it a little bit of
help thermally to kick in to start the reaction.
Next chart, please. Again, a little
cartoon here showing the constituents of NCFI. I just
chose NCFI as an example. You have a Component A and
Component B. The Component A is the isocyanate,
Component B is a polyol and all the other ingredients
such as blowing agent, flame-retardant packages,
surfactants, and catalyst packages.
ADM. GEHMAN: Is this a good time to talk
about blowing agents, or are we going to talk about it
MR. SPARKS: Let's go just a little bit
Next chart, please. This is really an
eye chart, but it is in your package and I wanted to
include that so it would be in your package. Maybe
what I just want to speak to is the blowing agent
issue. I listed the HCFC material on the top, and the CFC material is the second material in the top row,
materials that have been transitioned away from.
One of the questions we're asked often
is, generally, from a material properties perspective,
what happens when you transition from an HCFC to a CFC.
Generally, what we've seen and what this chart points
out fairly well is that at room temperature and
elevated temperatures your tensile properties and
compression properties went down a little bit only on
your NCFI series of materials. The other materials,
the PDLs and the BXs and also the cryogenic properties
of the NCFI materials seem to be equivalent or superior
with the HCFC materials, blowing agents.
MR. HUBBARD: One question before you
leave this chart here. I think I'm correct in saying
that this column here is the bipod ramp material,
MR. SPARKS: That's right, Mr. Hubbard.
MR. HUBBARD: Specifically, BX-250?
MR. SPARKS: That's right.
MR. HUBBARD: One of the issues that
people have been debating is how heavy a piece it was
that fell off the bipod ramp and hit the wing leading
edge. I notice that there's a range here and the
density which, of course, tells you how heavy it is; but you have a typical number. How typical is the
typical number? If you were to go take 15 samples,
would they all be very closely grouped around 2.4 or
are you going to see this full spread which is
something like, you know, a 40 percent spread?
MR. SPARKS: Right. If 2.4 was typical
in an area, the foam is going to give you variation.
It's going to give you variation in mechanical
properties. It's going to give you variation in the
density. I would presume a 2.2 to 2.6, that much of a
spread; but that's just a guess, Mr. Hubbard. It might
span that range. I don't think it's going to go down
to 1.8 all the way up to 2.6, but it's going to come
close probably. I think Lee's got a chart also that
might discuss that a little bit also.
Next chart, please. Moisture absorption.
I did pull some limited information, but I did want to
present that. The bottom line of the story is the
material is fairly moisture resistant as far as to
absorption. This is a study that was done, again, back
in '98, I believe, done upon 1-foot-by-1-foot panels
that had a substrate. They were sprayed upon a
substrate. So they were exposed on top in accelerated
exposure chambers, at 7 days for 125 degrees F,
percent relative humidity. You can view the amount of moisture gained for the NCFI 24-124 at .12 percent.
The BX material's at .16 percent; SS, .42 percent;
PDL, .83 percent.
Personally again, in working with a lot
of foam materials and measuring those foam materials,
those essentially are about the same because you're
going to see a lot of scatter in the data that you
receive lot of times from those materials. It would be
hard for me to say that there is a difference here. I
tried to go back and find the numbers of samples that
each of those numbers were up against and I couldn't
find that, but I would guess that the range certainly
you couldn't differentiate between any of those as far
as moisture gain.
MR. HUBBARD: Do you know of any studies
done, instead of at 125 degrees, closer to freezing?
MR. SPARKS: No. We're looking at that.
We've been made aware of that. We're going to look at
that and investigate that possibility. We know that
possibly that might be linked to the chemical
formulation, the ethylene oxide or propylene oxide
ratio. We're also going to try to figure that out and
see if it's applicable to our cryogenic situation.
One of the issues, though, Mr. Hubbard,
the tank very rarely would be at 32 degrees, being at Florida. Say, if it was frosty during loading, it
would be for a limited amount of time; but still we're
going to check into that and make sure we run that down
and possibly set up some tests to look at that.
Next chart, please. Actually this is a
chart that I presented a few years back, just a
high-level chart of some of the things that we do when
we go off and try to look at qualification. Physical
properties, we look at bond tension. In other words,
material that's been sprayed on a substrate. We test
it all the way down from cryogenic temperatures up to
positive 300 degrees F. We do a flat-wise tension,
which is blowing ice, just looking straight at the foam
material. We do plug pulls, density, and compression
on those materials. To give you a rough feel, probably
maybe several thousands of those tests in that test
Mechanical properties. Cryoflex is a
very severe strain, checking the ultimate strain
capability of that cryogenic temperature material.
Monostrain is getting design information as far as
modulus, and we do that at cryogenic temperature and
elevated temperature. We do some shear and some
Poisson ratio. Again, a lot of these pieces of data
are feeding into analysis; and we're doing, again, a swag, thousands of those.
Thermal properties. Thermal
conductivity, we take it down to cryogenic temperatures
and measure it all the way up 200 F. We look at the
oxygen index. In other words, what percentage of
oxygen. Is it flammable. We look at the flammability
as far as its flame capability of extinguishing itself.
Specific heat and TGA, more or less looking at when the
material starts to lose its weights as you increase the
temperature. We do aero-recession and hot gas wind
tunnel and we do thermal-vac, which is a synchronized
radiant heating and vacuum profile. We probably do
hundreds of those tests.
Then we do major flight acceptance tests
that are more or less all at config tests. Of course,
you don't do as many of those, but those ultimately
receive a little bit more visibility and really have a
little bit more fidelity as far as representative of
Next chart, please. A processing chart.
Again, this is for BX-250. The message for this chart
is, looking at the two bipods, the ET 93 -Y bipod and
the ET 115 -Y, that did shed debris recently. We went
back and looked at the processing conditions to see if
there was anything outstanding about those. To this date, we haven't seen anything that's really sticking
out. I very quickly put in a processing chart here.
The white box -- you can barely see it on this chart --
is more or less the invisible processing area that we
can conduct our activities. They're grouped in that
certain area there because that generally is the
temperature and humidity inside the factory at Michoud.
Qualification tests have been run at the
corners of the box, and you generally get about as much
variation from a sample down here and a sample up here
as you do if you get two samples in the middle. Again,
foam sometimes can be quite frustrating in terms of
data analysis because it does have certain variations
in the material.
Next chart, please. Again, looking at
mechanical properties of the past few bipod ramps and
looking at the 112 and 107 bipods. Both are falling in
the population average, if you will, of those I think
being sprayed. Almost going back to ET 106 through
These two points here, the chart is not
very clear on that. Again, this kind of demonstrates
the variability sometimes we'll see in the material.
These two low values were pull, and requirements are
that you pull right next to it to see if it was just a variation of material. I believe on this one it's a
, and on this one it's a 60, pulled right next to it.
That's one of the issues that you have often with
performing plug pulls is that you will get a bad plug
pull where the value will be low, but right next to it,
it will be just fine. If you dissect the material, it
looks just fine.
Next chart, please. We have these charts
for all the different materials; and this is just kind
of walking through, I guess, more or less a day in the
life of a person that follows cryoinsulation. It's
fairly frustrating as far as obsolescence issues and as
far as other issues mandated from other organizations.
BX-250 to SS-1171 to BX-265 is a good example.
Originally, of course, BX-250 was the original ET
material chosen for ramp and closeout applications.
In '93, the CFC 11 blowing agent manufacture was
discontinued. It was because of the accelerated EPA
date. In '95, the SS-1171 material was chosen to
replace the BX-250; and we secured the available stock
of CFC 11 to use with the remaining BX-250 that we had.
In '95, we had a flame retardant issue.
We have to obtain some material from overseas to
back-fill. In '98, production issues identified with
the use of SS-1171 sort of making us scratch our head. This is about the time that we were qualifying all new
materials going from CFC to HCFC materials.
What was occurring with these processing
anomalies were the SS material was processing just fine
in component shop, a little bit more control of
environment; but on the floor it was not processing as
easily. In 1999, again, SS was continuing to have
issues; and we discontinued that material in 2000.
Mondur Dark was the type of polyisocyanurate used in
BX-250. It was phased out of production. In 2001,
BX-265 is qualified to replace BX-250. Stepan is the
manufacturer of BX-250, and that's the BX-250 material
with a HCFC 141b blowing agent. And we implemented in
02, 2003, EPA phase-out of HCFC 141b. A waiver
approving that exemption was granted just recently,
March the 5th, 2003. That's generally just the life
and times of somebody trying to work these issues with
the materials sometimes when the raw materials are
ADM. GEHMAN: BX-265 doesn't appear on
your generic tank. It's used in the acreage and
replacing BX-250 now.
MR. SPARKS: That's right. I didn't
really label it very well. The previous tank, that was
ET 93 configuration. On that real big eye chart, you'll notice the transition in the upper right-hand
corner from BX-250 to SS-1171 to BX-265 did include
that material there. So that material will be phased
in and used in the areas where BX-250 is used now.
ADM. GEHMAN: And the shift of blowing
agents back in '93 was done strictly to comply with EPA
regulations, not because there was a better blowing
agent or your blowing agent wasn't working or anything
MR. SPARKS: That's correct.
All right. I'm going to hand the ball
off to Lee here.
MR. FOSTER: Okay. Scotty's first chart
said the TPS had to take the flight environments and
protect the structure. This is a sketch showing what
some of the environments are.
External tank, as also the rest of the
elements, have to take the aerodynamic loads and the
heating. We show this as hot spots, like on the front
where you have high aerodynamic heating. On the back
end of the tank, you have plume-radiation heating and
plume recirculation. You see in front of the orbiter
and SRB noses that there are shocks generated that all
impinge in the intertank region and even some of those
shocks coalesce and they're shown as separated flow and recirculation region right ahead of the orbiter nose
shock. As you can see from this, a lot of the areas on
the intertank and specifically in front of the bipod
are a very complex region.
The next chart is a computational fluid
dynamics chart that basically we borrowed from JSC, and
it is to show the complex flow field. I'm not really
going to go too much into that. I'm just going to let
you look at the pretty lines and see that the flow is
going every which way.
ADM. GEHMAN: Can you point out if there
are any shock-shock interfaces or reinforcing places in
MR. FOSTER: Well, yes, I can. The
previous chart showed the shock coming off the nose of
the orbiter. It's impinging there. The SRB on the
other side here has a shock coming through this way.
You can see the flow from the nose of the left-hand SRB
here. So it all coalesces into this area. You can see
that we're getting some vortices formed here and it
also has the LOx feed line here that influences the
ADM. GEHMAN: And you point out the left
bipod ramp. The density of the lines indicates more
stress, I guess, or aerodynamic pressure?
MR. FOSTER: I apologize for not being
able to answer well the CFD. I can barely spell it. I
told you I was an old technical guy, and this is a lot
of new stuff here. But, yeah, I guess it's like
watching the weather. When the lines are close
together, it's higher pressure there. I can get back
with you with the specific numbers there.
DR. LOGSDON: One more question. Foam
came off on 107, about 81 seconds into the mission. Is
that the Mach speed at 81 seconds?
MR. SPARKS: Yes.
DR. RIDE: Just one more. From this
picture, you know, we're looking more directly at the
left bipod. I can't quite tell whether the flow around
the right bipod looks the same. Does it, or is it just
MR. FOSTER: No, it is different because
of the presence of the feed line here; and this
particular solution did not have real high fidelity
geometry upon the right bipod. They're working that.
This is a chart that's used for illustration here.
DR. RIDE: Okay. So you would expect the
flow to be the same around the left bipod and the
MR. FOSTER: No, it's going to be different. We can get those numbers for you, but what
we've shown with our flight history is that if we have
good foam and it's not affected by, I'll say, some of
the hypothesized failures we have -- and I'll show you
later on -- both sides take the environments. We'll
get into that in just a little bit.
Next chart, please. What we're doing
here is looking specifically at foam loss and debris.
There are three things that we, on the ET side, look at
to quantify the debris for us. One is the ascent
photographic coverage. You know we have hundreds of
cameras watching the ascent. We have groups at each
center that look over those things and try and identify
if there is debris coming off at whatever times they
can identify it. We also have the separation photos
that are in the umbilical well cameras. These, of
course, don't come back until the orbiter does. We
also have several occasions where the crew has the
hand-held cameras. Those are usually not quite as much
information that we get from that 'cause it's a while
before they can take those. Also, after each flight,
there's the orbiter tile damage assessment; and we look
at all of those things to try and quantify what kind of
debris we're getting from the tank.
There were some additional methods lately. We had several SRB cameras to look at the
intertank region. That was a result of IFA 87, which
I'll talk about in just a little bit; and we had one
flight where we put a camera on the ET. It was really
a very neat view until, at separation, the BSM clouded
Next chart, please.
MR. HUBBARD: Before you leave that one.
No. 3 there. Post-flight orbiter tile damage. Is it
your understanding that the tile damage that is seen
every flight mostly derives from ET debris?
MR. FOSTER: Not really. Let's go to the
next chart, and I'll answer it there.
This is the number of hits on the lower
surface of the orbiter. There's also charts for the
side and the top and all that. The blue here is the
total hits on the lower surface, and the red is the
hits that are judged to be greater than 1 inch in
diameter. There's some rather large numbers, you know,
of total hits. I guess we can average somewhere in
here. A lot of those are very small, that are due to
other things than ET foam debris. Like on the aft end
of the orbiter the heat shield, you have a lot of ice
forming on the SSMEs and the aft heat shield and you
get little dings, lots of those. There are areas where you get some ice, I guess, from the attach points, the
orbiter ET attach areas. Usually there's a lot of
dings around there. It kind of goes to a baseline
number somewhere in the 13 to 25 hits greater than
inch, which I'll again get to in the next chart, if
we can go to that.
What you'll see here is where we had ET
debris events. We had some higher numbers. I'm slowly
getting around to answering your question, sir. This
is the same data as was on the previous charts, only
this is the hits greater than 1 inch. First let me
talk to this one at the very top. That's STS 27R right
after we got back to flight. That was a very large
number of hits. Most of that was caused by SRB debris.
There was a large investigation that worked that, and
so I'm really not going to talk to that particular one.
We will talk about these areas where there are large
numbers that we say are correlatable with the ET
debris. Then the rest are very small numbers,
relatively speaking. So, yes, we can tell when it's ET
derived damage; and I'll show you how we have
correlated some of those and what we've done about it.
GEN. HESS: Before you move on, have
there been any instances where you have foam striking
on the RCC that have been documented? This is just tile acreage mostly, is it not?
MR. FOSTER: I really can't answer that
question. We use the data that's provided by KSC, the
orbiter damage maps; and we're looking at the numbers
here. So I'm not the right one to answer that
MR. SPARKS: To my knowledge from the
laboratory perspective, I've never been informed that
the RCC was damaged due to foam debris. That's not to
say that it hadn't been. I've just never had knowledge
MR. FOSTER: Next chart, please. This is
an umbilical well photo from STS 26, where we had a
very large number, 179 hits greater than an inch. Let
me point out that there is an area around the flange,
extending up into the intertank and then around the
feed line fairing, where we have what we call two-tone
foam. This was initiated when we went to the
lightweight tank series, and it was an attempt to
reduce the environments by filling in stringers with
BX-250 foam. Then we could spray a smooth layer of the
CPR on top of that and reduce the environments. That
worked quite well, and these data start at the first
lightweight tank. It worked quite well until STS 25.
And then STS 26 -- 25 we did not have umbilical well cameras; 26, we did. These were flights that were
three weeks apart. This is where we had a sub-tier
vendor make a change on the isochem material that we
put between the two layers of foam. And this caused a
reaction and got a blister area, a void that then
popped off during flight. You can see there some
rather large areas where we had divots come out.
So after this flight, we went to a
process of drilling holes in all of these two-tone
areas, on 3-inch centers, in order to relieve the
pressure so the foam wouldn't divot. And it worked
quite well. As you see, the numbers went down.
ADM. GEHMAN: Is this an ET separation
MR. FOSTER: This is ET separation,
umbilical well camera.
ADM. GEHMAN: Oh, but it's from the
umbilical well, not from the crew hand-held camera.
MR. FOSTER: Yes.
DR. RIDE: Can I just ask a question on
your numbering system? STS 26 was return to flight?
MR. FOSTER: No, that was 26R. I do have
to apologize here. What I did was sorted these data by
ET number; and as you're well aware, the numbering
system was really messed up. So this is not in chronological order. Case in point: 27R is return to
flight, and 27 was way before. So although on this
chart those data would be together, you know,
chronologically they're far apart.
DR. RIDE: So could you just tell us what
flights these referred to?
MR. FOSTER: This is STS 26 -- I've put
down the STS number; and a little later on, where I
talk about some of the efforts we made to reduce the
debris, I'll talk specifically the ET numbers here.
DR. RIDE: I just needed the STS number.
The flight labeled STS 26 --
MR. FOSTER: Yes. That's correct. That
is STS 26.
DR. RIDE: That is STS 26, the return to
MR. FOSTER: No, ma'am. STS 26. There's
R. In our wisdom, we've flown an STS 26 and a 26R.
DR. RIDE: Okay. What's STS 25?
MR. FOSTER: STS 25 was flown in June
of '85 and STS 26 was flow in July of '85; 27, in
August of '85. So there were three of them right close
together there; and then, as I said, the 27R, this one
up here, wasn't until December of '88. So I apologize
for not putting these in chronological order.
DR. RIDE: So the one you labeled STS 25
is actually before the Challenger flight.
MR. FOSTER: Yes.
DR. RIDE: So it had a different
MR. FOSTER: Yes, it is.
DR. RIDE: And it was not the
MR. FOSTER: Right. STS 25 is
close to -- it's the early 20s, I think. It's hard to
keep up with. I'm sorry. I'm going to redo this chart
with everything done in chronological order.
DR. RIDE: It would just be useful to be
able to track these back to the actual flight numbers.
MR. SPARKS: We can get that.
MR. FOSTER: Go to the next chart. This
is 32R, which is a return to flight. This one, you see
we're missing a big piece of foam there that people
have looked at and said, oh, that's a bipod missing.
What you've actually got is -- this is, again, the
two-tone foam area. We see that we have lost the foam
in that two-tone area and it has taken the first part
of the wedge from the bipod. So really the bipod foam
loss here at the front edge is a result of another
divot as opposed to being, quote, a bipod foam loss. This one here, I've got it shown 13 hits greater than
an inch caused by this amount of foam coming off.
MR. HUBBARD: Would you just remind us
why 1 inch is an important number?
MR. FOSTER: That 1 inch is -- I guess
the system came up with that break point because they
were getting very large numbers of total hits. So they
wanted to come up with some criteria of things they
should look at for trending so that they might want to
take some action if they saw a large number.
MR. SPARKS: I think they had numerous
very small-speck hits they didn't attribute to possibly
debris falling from the external tank. So they wanted
another classification, and that's where they drew the
line. Of course, it was easiest to say 1 inch.
MR. FOSTER: Next chart, please. This is
STS 47; and as you can see, there were one large divot
here, a bunch of smaller ones, and even something on
the outboard side. The purpose of putting this chart
in here is twofold. One, the damage result was only
three hits greater than an inch. What I'm attempting
to show here is that it's a time-dependent thing,
depending on where you lose the foam. Now, going
back -- I don't have any information of exactly what
time that came out, but if it's early in flight or later in the ascent flight, you're dynamic pressure is
not at its maximum and so you don't put as much
momentum on a piece coming off and therefore it's not
going to have as much damage to the orbiter. So
there's a lot of people studying the transport of
debris; and it is a function of when it comes off, how
much damage it can do. STS 112, we had a very large
piece come off, but it never hit the orbiter at all.
By the way, this second point here is
that even though there were only three hits greater
than an inch, an IFA was taken on this tank, to go and
investigate why you're losing foam.
MR. HUBBARD: Just to be sure I
understood that point you just made, which I think is
an important one, is that it depends on when in the
flight the foam shedding occurs, how much damage a
given piece might cause?
MR. FOSTER: Yes, sir. Both from the
trajectory -- the transport over to the orbiter.
Because the flow field is constantly changing and then
also the amount of entrainment you can get in the flow
and therefore the more damage potential.
MR. WALLACE: Sir, you said on STS 47 an
IFA was taken.
MR. FOSTER: Yes, sir.
MR. WALLACE: Was that the decision or
recommendation of the external tank project then?
MR. FOSTER: Most IFAs, I believe, are a
system call which the ETs along with everybody else is
in the decision-making process. I don't think I can
say that it was something requested by the ET here or
whether it was just the system said, you know, this is
a big piece of debris, we need to go look at it. I
really can't answer that question.
MR. WALLACE: Do you have any further
recollection as to whether it was a constraint to
flight or what actions were taken?
MR. FOSTER: I know it was not a
constraint to flight. All of the debris that we have
here has been judged by the system as not a
safety-of-flight issue but a maintenance issue; and we
have all in the past been involved in those decisions.
Rightly or wrongly, they were all declared a
maintenance item and not a safety of flight.
MR. WALLACE: Might affect the
turn-around of the orbiter.
MR. FOSTER: Yes, sir.
The next chart is STS 50. This one had
hits greater than an inch, but it was one where we
lost the bipod but, again, in this one it was initiated in that two-tone region. Now, you've heard a lot of
the two-tone. After STS 50, we changed away from the
two-tone; but this one is one we looked at recently
where we tried to get a solid model to show what the
dimensions were. The weight calculated for this
particular area, which included the front of the ramp
and a little bit of the two-tone area, was about a
MR. HUBBARD: When in flight did this one
occur? How many seconds after launch?
MR. FOSTER: I don't have that
MR. SPARKS: I don't know if we know
that, Mr. Hubbard.
MR. FOSTER: We asked the photo guys to
go back and look at all of these; and, quite frankly, I
haven't seen the results of that yet. I think, though,
that they said they did not see this piece come off
MR. WALLACE: So in some cases you only
know that it happened when you see the separation?
MR. FOSTER: Right.
MR. SPARKS: I think one thing that
they're additionally doing also now is if they came
back with a, well, we did see it come off, I think also they're going out and saying, well, this is the window
that we did not see it come off also, which would be
helpful. And I think they're working that right now.
MR. HUBBARD: Maybe this is a good point
to ask a different version of my earlier question. If
you go back to -- you don't have to go back on the
slides. But on Slide 17, the data commonly available
for assessment. You have ascent photos, orbiter
separation photos, and post-flight tile damage. If you
were to look at all the flights and say what is the
preponderance of the data that you're using to assess
what goes on, which one of those three would stick out
as where you have the most data?
MR. FOSTER: Well, basically the orbiter
tile damage, you know, we have that on every flight.
It's easily done. It's numbers that you bean-count.
The umbilical well cameras, sometimes you're launching
in darkness and so you don't get good coverage. We
have one orbiter that doesn't have the umbilical well
camera. So that's some information that is -- I don't
even know what percentage of the time we get that.
It's over 50 percent but by no means 100 percent.
MR. HUBBARD: And you may or may not
happen to catch it as it's coming off.
MR. SPARKS: Right. Or the camera may be out of focus or a cloudy day.
MR. HUBBARD: So is it a fair statement
then that, by and large, we know what we know about the
damage that external tank debris-shedding causes, by
virtue of looking at the tiles after the fact, with
some other data tied in?
MR. SPARKS: Right.
MR. FOSTER: We look at whatever we can
to get information.
MR. HUBBARD: So do you feel then, given
where the data comes from and how much you have got,
you feel fairly confident, then, that there is this
direct connection between the tile divots, at least the
larger ones, and the external tank debris?
MR. FOSTER: Yes.
MR. SPARKS: Let me take a cut at that
because the tile count, if you will, when it gets back,
is the one thing that's always consistent. You're
always going to get that data, but it is confounded.
That's the reason why it's so important to get ascent
photography or separation photography. You know, the
tile count is confounded. So any of that data that we
can get upon ascent, upon separation, on crew hand-held
are value added. Very much so.
DR. RIDE: Could I just ask can you characterize roughly the number of flights or the
percentage of flights where you've actually had ET SAP
photography or ascent video that clearly shows the
bipod ramp? What I'm getting at is: How do you know
what percentage of flights foam has really come off the
MR. FOSTER: I don't know that we can
make statements with certainty. All we can say is that
by looking at all these resources we have, we can see
things like this that give us that information. The
ones we don't know about, it would just be guesswork.
However, a lot of them that we could not see, we also
did not have big debris damage. So I'm not sure if
there's any comfort in that.
GEN. DEAL: Rephrasing her question a
different way, do we know how many we have seen either
through the separation or hand-held? Because we've got
the ones at nighttime we definitely didn't see and
we've got the ones where we didn't get the camera shots
out of or where the tank had rolled around. Do we know
how many we have seen?
MR. SPARKS: We've got that. I don't
have that, General Deal, on top of my head. I have
seen it, but I just can't remember what it was.
GEN. DEAL: 'Cause we throw around terms, you know, four out of 112. It may be a lot more than
that 'cause we can't confirm that.
DR. RIDE: Right. That's what I was
getting at in a pretty badly phrased question. How
many tanks shed debris where it could have come from
the bipod but we just don't know because we didn't have
MR. SPARKS: And I think in between 112
and 107, I believe 113 was a night launch, if I recall
MR. HUBBARD: If you expand the question
to the whole external tank and all of the foam that
you've got there on the acreage, is it fair to say that
if you look at any one of these plots that go up
through more than the 100 flights there that all those
little red triangles probably, or many of them,
probably relate to the external tank?
MR. SPARKS: I would say the majority of
them do, Mr. Hubbard. That's Scotty speaking, though.
MR. HUBBARD: Okay.
MR. FOSTER: Let's go to the next chart.
Well, before then, let me answer that question, the
previous question just a little bit more. We think we
have evidence of five flights, I think, where the bipod
has come off. Of those, the ones I showed on the previous charts, we don't see the bipod as being the
initiating mechanism. That two-tone foam was. So
really it's kind of, well, we've only had a couple that
we know of that were bipod alone.
This chart shows STS 87, which was 109
hits. This one was the initiation of the IFA 87, it
was called, because we had a lot of popcorning type
foam loss on the thrust panel side of the intertank.
That was worked very hard through the investigation
procedure and it has been handled with the application
of thousands of vent holes --
ADM. GEHMAN: This was the first flight
after the shift of blowing agents, right?
MR. SPARKS: It was the second flight.
ADM. GEHMAN: After the shift of blowing
MR. SPARKS: Right.
MR. FOSTER: Next chart, please.
ADM. GEHMAN: Let's go back one before we
get off that chart. I haven't done any kind of a
scientific analysis, but we've looked at about seven or
eight of these charts now with those little red
diamonds down across the bottom. By rough order of
magnitude, it looks to me like the number of hits
greater than an inch is a straight line, a straight horizontal line. It's not obviously diminishing.
MR. SPARKS: Correct. It looks like it's
averaged about 16, 17, I believe, 20. I think I ran
the numbers before I came in. For the CFC materials,
it was 20 some odd; and for the NCFI materials since
the full-up venting, it's been, I think, about 16, 17.
ADM. GEHMAN: The point is the trend is
not going down, not by any order of magnitude, anyway.
MR. SPARKS: Correct.
MR. HUBBARD: Is that taking out or
leaving in the large events?
MR. SPARKS: The CPR numbers are taking
out that 27R event. I did take that one out. So it
would run it up just a little bit.
MR. FOSTER: Next chart. This is a list,
a not completely comprehensive list of everything we've
done but a list of efforts to reduce debris. I
apologize that the font is so small on this. You could
probably do better reading it on your handouts.
STS 1. We had some instrumentation
islands on the LOx tank. There was a concern that we
were going to make ice on those. So we removed them
until we could verify that instrumentation islands
wouldn't form ice. So, you know, we've been concerned
from Day 1 with debris formation.
When we got to the lightweight tank
series, which started with ET 8, this was a block
change to the lightweight tank series and it enabled us
to go do a few things to help reduce debris. One of
the things was redesign of the bipod ramp angle from
degrees to 30. Now, this was done on lightweight
Tank 7. So these things I talk about as a block change
are incrementally implemented; but that was to reduce
the loads, the air loads on the bipod ramp.
Now, STS 7, which I do not have a --
well, I guess I do have a picture somewhere in here.
STS 7, at any rate, had bipod foam come off, but there
was a very large repair done to the bipod ramp and it
was judged that that was the key driver for losing the
bipod ramp on STS 7. So we did two things. One, we
incorporated the maximum repairable defect limit on the
bipod ramps, said if you have to repair more than this
size -- and it's a very small size -- take it off and
start over again. And also we changed the ramp angle,
saying that's going to reduce the air load. So those
two in concert should really help the bipod ramp.
Also on some of the STS 7, we saw that
cable tray ice frost ramps had come off. The block
change to lightweight enabled us to change to a
two-step single-pour application process versus the old one-step multi-pour process, and what this did was gave
better structural integrity to those ramps. We also
reduced the super-light ablator areas on the tank. We
had large areas of the super-light ablator running all
the way down the pressurization lines, and we removed a
lot of that and also deleted the anti-geyser line. So
there were a lot of things done at the lightweight tank
initiation, one of which was incorporating the two-tone
foam configuration. That was an attempt to reduce the
environments and help in foam loss prevention.
ADM. GEHMAN: What does two-tone have to
do with it?
MR. FOSTER: Two-tone was the area that I
showed around where we filled in the stringers. What
that did was reduce the aerothermal environments in
that region by having a smooth surface as opposed to
localized stringer effects. It turns out that was
probably not one of our best decisions; but, you know,
we weren't planning on the vendor changing in the
On STS 27, we saw some large intertank
divots that I showed you, the umbilical well camera for
STS 26. And a corrective action was to drill holes in
the two-tone areas to take care of the debris use to
the isochem bond line issue.
STS 32R in 1990, we had the intertank and
associated bipod part come off. The problem there was
the vent holes that we were drilling did not go down
far enough. So they pin-gauged them to make sure
everything was going down the right amount, fully vent
this area where we were getting de-bonds.
The STS 35 in 1990, also there were ten
areas on the flange where divots were observed. This
started a process to investigate why we were getting
flange divots, and the result was that there was an
improved process to spray the foam around the flange
bolts. They were getting a void underneath the bolt
because of the spray pattern. They changed the
technique for spraying it so that you could ensure you
weren't getting a void underneath there. That helped
and we're still getting flange divots, but not as many
as we were before that change. So it's gone in the
STS 50 in 1992. The jack-pad area, which
is an area between the bipod where we have a tool
helpful in holding the bipod during mating operations,
when you remove that tool, you have to close out that
area. The method that they were using led to void
areas. They changed the process to keep from forming
those void areas. Even though I don't have it on this chart, there were two or three other changes made
specifically on the jack-pad to ensure we didn't get
those coming out as debris, the foam in that area.
And, Scotty, do you know? Have we seen
jack-pad area debris recently?
MR. SPARKS: It's performed very well
since that configuration change.
MR. FOSTER: STS 46. Again, this was the
result of the observation on STS 50 that there was an
intertank/bipod divot. Added some more vent holes
right in front of the bipod ramp in that two-tone area
to try to decouple those things and see if we could
keep the intertank two-tone region from ripping off the
front of the bipod.
Finally in STS 54, ET 51, because of all
these previous problems that we talked about on the
two-tone foam on the intertank, we incorporated a
two-gun spray foam application to replace the two-tone
foam. So ET 51, STS 54, was where we got rid of the
STS 56 in '93, we saw ten large divots on
the -Z intertank acreage area and there was a study
that looked at that and the process was changed in
order to try and reduce the rollover and crevassing
that Scotty talked about a little bit earlier.
MR. SPARKS: I think there were some
processing changes that were made, and that process has
also been approved, has improved the performance of
that intertank area.
MR. FOSTER: Then STS 87 was the
popcorning of foam off the intertank, and there was an
increase in the number of tile hits. So there was the
large IFA effort that the external tank program went
through, and basically we incorporated the vent holes
to keep that from happening and that has worked very
On 112 we saw the bipod foam loss. This
was at 32 seconds, I think. It basically was the first
bipod foam loss that we could say, you know, this was
not associated with the two-tone; and it was the first
thing that we had seen in quite a number of years. So
there was a corrective action that was kicked off, and
I won't go into what they were really going to change
there. They were going to remove SLA from under the
foam; and that is hypothesized as one of the factors
that can lead to bipod foam loss, which I'll get into
in a minute.
I'm going to switch over to cryopumping
and cryoingesting before we have any other questions on
MR. HUBBARD: Before you leave that and
go to cryopumping, this is a very impressive list of
all the things that have been done over the last
years to address the shedding of external tank
debris. Nevertheless, if you go back to any of the
charts that have the red triangles that indicate the
divots greater than an inch, which is one of the
characteristics that you look for, the line is pretty
much a flat line there. I mean, whether it's 10 or 15
or 20 or whatever. So do you see any way to drive that
line down to zero or near zero?
MR. FOSTER: I'll let Scotty go first on
MR. SPARKS: Well, I think we're always
trying to improve the product, but we don't want to
change the product unless we're justifiably sure that
that's going to improve the product. One of the things
we did that's not captured on this chart is we changed
from a nose cone that did contain insulation to a
composite nose cone that has no insulation. That took
us completely out of the realm of shedding debris, of
course, in that area. So that's one of those things
that you know you're going to remove a failure mode out
of the way if you do that. So that's one of the things
that has happened.
So there have been several improvements
that I think the program or project has been proactive
in pursuing. Indeed, there's still a level and, you
know, they're coming from those closeouts in that
intertank region that seem to be problematic. We try
to improve our processing to the extent possible, but
thus far it's staying in that 15 to 16 range.
MR. HUBBARD: To follow on that a little
bit, I guess if I had a problem that, over 20 years,
the average stayed essentially constant, it seems to me
that that might argue something about the basic
chemistry or basic properties of the thing you're
dealing with, the foam itself. I mean, do you see the
foam as being difficult to control in a very precise
MR. SPARKS: No, I don't Mr. Hubbard.
Really what I'm seeing -- again, from my opinion and I
think probably a generally held opinion -- is that it's
an issue of trying to process that material the best
you can. You know, if I had to take a guesstimate as
far as the location where we're shedding the most
debris, it would be in that hydrogen intertank flange
area. That's just a hard area to close out. There's
lot of bolts there and when you're spraying that
material, a lot of potential for shadowing that foam and possibly having some voids behind that. We've
always attributed that to the reason why we're losing
some of that material in that area. Of course, the
other closeouts. Just a little more difficult. A
little bit more random as far as being able to shed
that debris. Even though, say, in the hydrogen tank
where it seems like the environments, as far as
cryogenically are more severe, it's robotically sprayed
upon, a very smooth, flat surface. It's those
closeouts on complex geometries, I think, that it's
MR. HUBBARD: So then just to follow this
to the end of my question on it is that it's the
system. You know, you've got a foam and it has to be
applied over a certain type of underlying structure and
making that so that it is free from shedding seems to
be, over the last 20 years, a tough thing to do.
MR. SPARKS: Yes, sir. Generally, I
mean, you've really got to go back to the beginning, as
far as the design of the tank. I'm not so sure that
the TPS processors were in the same room when they
designed the tank, because it was designed structurally
to be optimized. It's not designed for the TPS to be
processed on there. If you were to redesign completely
a tank, you would make the external a bit smoother, you would have those people in the same room, and you would
do those trades. You know, if it's worth it, you would
do it. So you've got to insulate what you've got, and
I think they're doing a heck of a good job. They
maintain a lot of skill in that area and, indeed, it's
flat line about 15 thus far.
MR. WALLACE: I think you were probably
sitting in the earlier session today.
MR. FOSTER: Yes, sir.
MR. WALLACE: There was a discussion
about whether this 112 event wouldn't be an in-flight
anomaly or not. Can you speak to what the ET project's
position was on that?
MR. SPARKS: I think the position was
that it was a random occurrence of faulty processing
and that it was nothing had changed in the system to
indicate that that was a systemic issue as far as
processing of material. They had gone and done their
homework, as far as that goes; but I think when 107 had
occurred, I think that would have kicked it into
another issue. If I recollect right, I think there was
an issue of an IFA pending photographic analysis upon
return of 107.
MR. WALLACE: And with these two
observations, Mr. Foster noted that this was the first time since you had changed, gotten away from the
two-tone foam and it was not associated with two-tone
foam and also the fact that it hadn't happened in ten
years. Would that sort of argue more in favor of or
make it an IFA or against that?
MR. FOSTER: I guess that would have to
argue in favor of making it an IFA. I can say that
after the 112 the project did say, okay, we do not want
to release that big a piece of debris. It hit the SRB
and did no damage there, but still it was a large piece
and the project said let's go look at redesign options.
MR. WALLACE: When you say it did no
damage there, do you mean it didn't threaten the
flight? I sort of understood that it actually did some
MR. FOSTER: The 112 particle that came
off at 32 seconds, it came down and hit the IEA box on
the SRB and I believe -- and this could be secondhand
information -- but I believe that it didn't do much
damage at all to the foam and the TPS on top of the IEA
box. I'm sure there's better information available
from other people, but I don't think it was a large
DR. LOGSDON: Is there a program-level
requirement for debris-shedding or lack of debris-shedding on the external tank?
MR. FOSTER: The program-level
requirement is that we shall release no debris that is
harmful to the orbiter. So it's a very subjective
thing; and while we have been working hand in glove
with the system over the years, you know, we've worked
with them on debris teams and the debris panel and all
that, again, everything was judged as a maintenance
item and not a safety-of-flight issue. I'm not going
to say that was right or wrong in the past, but that's
the way it happened.
Next chart. We'll go on to cryopumping,
and I'll go through these rather quickly. I'm sure
you've all heard of cryopumping, but the mechanism of
cryopumping is simply the transformation from a gas to
a liquid at cryogenic temperatures. The little graphic
shows barely a little crack from the ambient at room
temperature. When you get down to low temperatures,
the gases are condensed within a void or it can be a
porous medium and when the air in the cavity or this
porous material liquefies, which is what happens at
structural temperatures below minus 297 degrees F for
oxygen and minus 320 degrees F for nitrogen, it can
liquefy inside the cavity and what that does, it
locally reduces the pressure and basically sucks more air into the void. This is a process that continues
until you can fill up the void.
Now, in and of itself, that really
doesn't bother you. It's what happens when that liquid
tries to gasify and come out. If you have a
sufficiently large vent path for the gas to come out,
you know, no issue. You might see a condensation
cloud. If you have not a sufficiently large vent path
but one where you crack the foam and get, that way,
more of an escape path, you can relieve the pressure
without causing debris. But if the vent path is not
sufficient, as shown in the bottom sketch, you can
physically pop debris off. And we think we've seen
that on a few of the flights, like in the flange region
where it looks like it's a dinner plate that came out.
We can recreate that in the laboratory.
GEN. DEAL: Mr. Foster, say for the sake
of the argument if you looked at that and you had a
piece of tape or something that was blocking that from
escaping, that would make it that much worse and cause
a divot at that point?
MR. FOSTER: Yes, sir. It's a matter of
whether it's got enough vent area to get out. And
cryopumping is interesting because you can slowly, you
know, suck in air in hours as you're out on the pad. But when it comes time to gasify that, it usually
happens quickly and you build up large pressure and it
doesn't have a vent path to get out. Now, that is
cryopumping. Now, we have in the bipod region created
a term just so we can communicate. We call it
Next chart, please. This is with a
postulated method for getting cryonitrogen ingested
into the SLA. Let me orient you here. This is the
bipod spindle. This is the super-light ablator that's
over the spindle, and our heater element has a wire
that comes down here and the wire runs up through this
stringer into the intertank. What we're doing here,
this view is a view in this direction. So you see the
bipod spindle. Here's the wire that comes into the
intertank, and the shaded areas are the SLA. Then
you've got the foam over top of it.
Next chart, please. We have a nitrogen
purge in the intertank. We have an area -- during
fill, you will fill up liquid hydrogen in the tank and
it will go all the way up into the dome. You will get
the metal surfaces cold, below the liquefication
temperature of nitrogen. So we have our nitrogen purge
in the intertank and you're forming liquid nitrogen
down in this Y joint region. You also can get the nitrogen purge in through this single stringer
associated with this bipod there. We have two bipods,
so there's two stringers that have this SLA over the
wire, going up into a stringer. In this area you can
also get liquid nitrogen temperatures.
What I've shown on the right side is that
in this scenario that's postulated for cryoingestion,
you get liquid nitrogen that is sitting right on top of
the porous SLA material and it can absorb into the SLA.
Now, this is a photograph of the flange between the
hydrogen tank and the intertank. This is an area
between shims so that you can have an area that goes
all the way into the intertank here. I show that as
also being postulated area where you can get some
liquid nitrogen to come into the SLA. We don't know if
that's a true hypothesis, but we're trying to look at
everything to see if there's a mechanism for this thing
called cryoingestion to knock off bipod foam.
Next slide, please. With time, you can
absorb more of the liquid nitrogen into the SLA and at
some point your temperatures are going to be above the
liquid nitrogen temperature and you won't fill this
whole area with liquid nitrogen. The --
ADM. GEHMAN: That's all assuming the
heater is on and working, but the heater doesn't work back off the top of it.
MR. FOSTER: That's a true statement.
This postulation here shows that we form
solid nitrogen; and the timing is real critical here,
you know, whether you can ingest or absorb the liquid
nitrogen and how much you get in here before you get
solid nitrogen forming. The key to the solid nitrogen
forming is that blocks the escape path back through the
stringer. So you could have an area of nitrogen here
that during flight could generate pressure to try and
push off this bipod.
The next chart, though, shows you some
temperatures. Here's the temperature on the outboard,
on the top of the bipod. You see that it's basically
room temperature when you launch and then it goes up
with the aero heating, but what's happening outside
here doesn't really transfer into this area. The blue
line right here is the substrate, the aluminum
substrate, and what happens is at this time the liquid
level in the hydrogen tank has gone down and so your
ullage temperature is warming this area up a little
bit -- "warming" being a guarded term because we're
still below minus 300 degrees F.
The other point here is that this area
which is between the SLA and the BX -- or it is that interface -- it really doesn't respond to either of
these temperature changes. So there's a real critical
timing in both how you get liquid nitrogen in there and
how you get it out for this scenario, but it's one that
we are looking at very seriously and have a bunch of
tests that we're going to run to say yea or nay on this
DR. RIDE: What's the temperature of the
solid liquid transition?
MR. FOSTER: Minus 346 degrees F.
MR. SPARKS: Dr. Ride. Nitrogen? Minus
DR. RIDE: That happens before a hundred
MR. FOSTER: Let me point out that this
thermal analysis here did not take into account the
effect of nitrogen in the SLA, which would change the
thermal conductivity a little bit and would change
these numbers. We have programs to try and put liquid
nitrogen in SLA and measure the conductivity, but
that's a tough thing to do. But we're going about
trying to get that.
The next chart. Notice in big words this
is preliminary graphics. We have gone through the
dissection program on ET120. What I wanted to show you was that we do have some defects, rollovers, voids
inside the foam and the SLA. I wanted to show you a
solid model and make it real pretty, but this is an
early shot at it. We'll get better in the next couple
of days, but this is showing you where during our -Y
bipod dissection. The yellow are little foam items
that we saw. Most of these are rollovers. So don't
judge anything by the shape here too much. And we had
green areas, some SLA items, which are very hard to
see. We had a couple right in there. The clevis
itself, while it's shown as green, is not a SLA item.
We'll be showing you these Thursday, I
think, when you're coming down; and the graphics will
be a little bit improved. Basically the intent of
showing this chart was to say that we have gone through
the dissections and we're proceeding on getting ready
to go to dissect ET 94 to see what kind of foam we have
and what kind of SLA underneath there so that we can
take those into account in the testing we do to try and
look at what happened on 107.
Next chart. I'll let Scotty finish up
with this chart here. It's the progress, I guess,
MR. SPARKS: This is a chart showing --
the top picture being STS-7/ET-6. All materials were CFC-based materials. It kind of shows certainly the
craftsmanship that has improved to STS 112, a
separation photo. You certainly can see a lot of
improvements as far as the workmanship of that
material. So certainly there's been significant
improvement and there's a lot to be corrected, but I
think certainly the material and the processing has
been improved over the years.
ADM. GEHMAN: All right. Thank you very
GEN. HESS: Y'all have a very rich
history with this particular problem, and I can see
visually by the chart that improvements have been made
over time. My question really is: Did you ever think
that it was possible to pop a big enough piece of foam
off of this external tank to severely damage the
MR. FOSTER: I'll take a shot at it
first. The answer is yes, you know. We have large
areas where we have closeout materials that we know are
hard to spray. So, yeah, we are always worried that
there's going to be a big piece that comes out that
would throw us over that maintenance item line.
MR. SPARKS: Let me throw in my opinion
there, too. I agree with Lee. We watch very closely ascent. That's because we know that that material
could come off and cause some damage. So we understand
that that's a potential and we understand that it does
require a lot of focus on processing that material to
make it not do that.
GEN. HESS: I get a little bit lost in
this characterization that it was not a
safety-of-flight issue, it becomes a maintenance issue,
which is what we hear on most instances, frankly.
MR. SPARKS: You do hear that a lot, and
maybe that was because, you know, maybe the
predominance of those pieces of material coming off
have been small in the recent past, but there is still
a lot of concentration, a lot of focus upon not
ADM. GEHMAN: Let me ask a question.
Have you discussed or ruled out or considered a
pre-formed bipod ramp piece of insulation, a molded
piece that would be physically attached and that would
be in some way reinforced with some structure that
would not come apart.
MR. FOSTER: Yeah. There's a separate
group that's working the redesign options. Scotty and
I have been working the investigation. I assume later
on we'll transition over to looking at the redesigns. They're doing exactly what you're talking about,
looking at ways to keep from having a complex geometry
to have to spray or incapsulate. So all of that is
working towards making sure that the spray is not too
big a challenge to the techs that do it.
ADM. GEHMAN: As I understand it, there
are other places on the ET where there are pre-formed
pieces of insulation like along the lines, for example.
MR. SPARKS: Right. Right.
ADM. GEHMAN: Gentlemen, again, thank you
very much for being so patient with us as we worked our
way through molecular structure and polymer bonds here.
This is obviously a very serious issue and an issue
that's going to get a lot more attention before we're
finished here, and I want to thank you for answering
all our questions so completely and helping us do this.
I also want to wish you all the very best
of luck in the two or three different hats you wear as
you both do your day job and also work at finding out
how we're going to fix this. So thank you very much.
All right. Board, we are finished for
today. See you tomorrow morning.
(Hearing concluded at 5:01 p.m.)
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