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Let's get started.

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Again, just putting things in perspective,
Professor Cohen talked about how in a big

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engineering design project you work through
the various stages.

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And the first stage is phase A where you come
up with the basic concepts.

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And I think the level of detail of the system
and subsystem lectures that he is giving,

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last lecture and today, we could sort of look
at as being on kind of the phase A level to

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show the basic feasibility and the overall
structure.

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Those of you from aero-astro have certainly
been familiar with our approach to systems

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engineering which we call CDIO.

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Someone from aero-astro can tell me the C
is conceive, design, implement, which actually

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means manufacture and test, and operate.

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So we're kind of dealing in these first few
lectures.

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And this could be looked at as phase A and
then the detailed design, that's your phase

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B.

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That ends with the critical design review
after which, in principle, you're supposed

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to be ready to cut hardware.

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And then you get into the phase CD where you
actually build and test.

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And then, of course, we operate.

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My sort of background, the way I got into
engineering, and I probably should have mentioned

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this at the beginning as sort of truth in
advertising is I was never trained as an engineer,

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unlike Professor Cohen.

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I was actually trained as an astrophysicist.

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But, when I went to NASA, I spent so much
time working with all the technical systems

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and interacting with the engineers and the
people who use them that I learned certainly

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a lot about the way these systems are designed
and particularly operated.

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So my approach to a lot of these engineering
situations is very much from an operator's

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point of view.

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And I will try to emphasize that as we go
along.

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Very important, right from the beginning of
the design, I think that you think about how

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you're going to operate the system.

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We have had too many examples that I've come
across and many people who have to actually

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operate systems where you build something
without really thinking of how the system

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is going to be maintained and taken care of.

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One of the things that we have been doing
for the last few years is to take a group

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of undergraduates down to the Kennedy Space
Center every January, an interim activities

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period, and have them spend a couple of weeks
with the engineers and technicians who have

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to maintain and operate the shuttle system.

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And they hear lots of stories from the engineers
and particularly from the technicians who

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say, boy, I would like to have a chance to
talk to the person who designed this little

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system.

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And I have to get my hand all the way around.

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And it takes five hours to turn the bolt or
something more fundamental.

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And we will probably discuss this when we
talk about the main engines.

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The fact that originally the main engines
were supposed to be reusable without being

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taken out of the shuttle so that you could
cycle them many times.

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Well, it turns out that in order to get sufficient
confidence that the engines are ready to fly,

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we really do have to take them out after every
flight.

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And they are extensively borescoped when you
look inside.

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But some of the engineers in the main engine
shop pointed out that, for instance, if certain

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diagnostic test equipment had been built into
the engine so that you could have taken data

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as the engines were shutting down over and
above the data that we actually get, possibly

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we would have been able to reduce considerably
the maintenance on those engines.

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Again, the shuttle was the first time we had
really tried to design reusability into a

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space vehicle and engines.

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And we've learned an awful lot.

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So I think it's very important when we discuss
the systems in the course of the term that

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we don't just look at the detailed design
but we also consider the operations.

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That's very important.

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In that spirit, Professor Cohen is going to
continue his introduction to the shuttle systems.

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And, Aaron, I will turn it over to you.

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OK.

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Thank you.

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As Professor Hoffman said, I'm really giving
you what I would call a technical management

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overview because, when we talk about structures,
on the 22nd Mr.

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Moser is going to come and talk about structures
and he's really going to go into the details,

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how the loads were calculated, how the stressors
were calculated, how NASTRAN was used, how

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we came up with the basic structure.

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But I'm just going to really give you sort
of an overview on it.

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And I think it's interesting to note that
the structures may be a very good system to

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look at for your project because it weighs
a lot.

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We certainly didn't have all the tools for
calculations that you have today to make it

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a more efficient structure.

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The materials are a lot different.

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But basically this structure, if you start
at the front of it, the crew cabin, which

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I showed you a little bit about being made,
a welded configuration, and the forward fuselage

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are basically an aluminum skin-stringer structure,
very basic aluminum.

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If you go back down to the mid-fuselage, which
is the large part there, it's, again, a skinned

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structure.

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Interestingly enough, the forward fuselage
and the crew cabin where made by Rockwell

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International in Downey.

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The mid-fuselage was made by General Dynamics
in San Diego.

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So we had various people putting the structure
parts together.

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The wings were made by Grumman.

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So we had this vehicle being built all over
the country coming to Palmdale, California

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for assembly.

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And the aft thrust structure was built by
Rockwell.

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The vertical tail, I believe, was built by
Fairchild on Long Island.

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Some of these places don't exist anymore.

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But then you go back to the vertical tail.

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Again, it is machined skins with honeycomb.

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The aft fuselage, as you can see, is very
complicated.

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It has all the plumbing, all the wiring, all
the auxiliary power unit, so it is a maze

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of plumbing and wiring.

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You could get lost in there and they'd never
find you again.

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But it is a maze of wiring and plumbing.

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And it's made basically of aluminum.

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But a lot of the support structure are boron/aluminum
thrust structure panels with graphite epoxy

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skin panels.

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And then the payload bay doors, which was
our innovative material going into large composites,

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we use graphite epoxy, that was the first
time that really a large composite structure

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was used in a vehicle.

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Now it's used quite commonly in the Air Force
and a lot of places, but graphite epoxy were

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the panels we used.

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And that saved a lot of weight.

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One of the problems we had, though, was when
we built these panels we found we got moisture

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trapped in it.

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And, of course, the moisture, when you heat
it up coming back it would pop the panels

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off.

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So, on the pad, we had to go in and drill
little holes in these panels to be sure we

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could get the moisture to escape.

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So those are things you learn when you do
new technologies.

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But, as I said, Mr.

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Moser is going to go through a very detailed
explanation of this.

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This may be something you want to consider
because there could be a real innovative way

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of reducing the weight and making the vehicle
more robust, so I suggest you think about

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that for the structure.

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Now I'm going to talk a little bit about guidance,
navigation and control.

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And some people asked me yesterday where they
could find some information on it.

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Actually, in those orange or yellow books,
I've forgotten what color they are, that we

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showed you that are on-hold in the library,
have a very detailed analysis and discussion

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of how the guidance, navigation and control
system was formulated.

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And it is probably as good as you're going
to find.

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It was very early in the program.

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It's a little bit different than it is today,
but it's a very good description of the redundant

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computer set, the fail-operational, fail-safe
system.

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So I think you could really get a lot out
of going through that book.

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I should just say it turns out that we have
two sets of those books in the library and

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they are on reserve so you can only use them
for two hours at a time.

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There really should not be any problem with
everybody in the class having access to those

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books when you need to go and look at them.

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That will probably be the best source, except
when Phil Hattis from the Draper Labs comes

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and talks about the guidance system.

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I will talk a little bit more about that.

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This chart or this schematic or whatever you
want to call it was originated by the Johnson

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Space Center and Rockwell International.

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It took us many hours but it basically is
the architecture, I am going to go through

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it in some detail, for the guidance, navigation
and control system.

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Now, this was the original one.

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It is a little bit different today, and I
will explain the differences that we have,

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but this was basically the guidance, navigation
and control system main architecture.

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And you can see on the left side, and the
left side is what I would call sensors.

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First of all, in a very simplistic term, some
of your experts in guidance, navigation and

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control, but guidance, navigation and control,
navigation is actually determining where you

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are, guidance is getting to where you want
to go and control is controlling the vehicle

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and its stability and its characteristics
around the center of gravity.

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So that's basically control.

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This is for the total guidance, navigation
and control system.

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Interestingly enough, the contractor for this
was IBM Federal Systems Division.

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We used their computer and they did the software.

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Much of the hardware was designed and built
by other contractors, and Rockwell International

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basically did the integration.

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And they did the integration on a system called
the Shuttle Avionics Integration Laboratory.

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It was basically a vehicle that was in the
laboratory that had all the electronics, the

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cockpit and everything in it.

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It simulated the actuators.

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The hydraulic system was simulated and the
engines were simulated, but basically all

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the hardware and software was in the Shuttle
Avionics Integration Laboratory.

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I imagine you spent some time.

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We actually had two.

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We had one in Houston and there was one out
at Rockwell.

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And, when Professor Cohen says that it was
a vehicle, you have to appreciate that it

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was actually laid out just like the shuttle
so that they had the controllers, which were

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in the aft end, like in the engine compartment,
were a hundred feet away from the crew cabin

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and the computers and all the lines, the data
and power lines were laid out as closely as

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possible to physically duplicate the layout
in the shuttle because there was concern about

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the timing of signals going back and forth.

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And they wanted to run the simulation as accurately
as possible.

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And then, of course, you have to have a set
of simulation computers to try to determine

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the environment that the shuttle would be
flying in so that it could make the inputs

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to the rate gyros and the other parts of the
measurement units to try to duplicate the

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flight regime.

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And here is an explanation of the alphabet
soup of all the systems, subsystems, components.

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On this side you see really the sensors.

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That's the information that you need to do
your navigation part of it.

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And then, of course, that information then
is sent to the computer through a multiplexer

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demultiplexer, MDM, which basically is an
analog to digital converter, digital to analog

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converter.

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The computer does its computations and then
sends it to the effectors which actually change,

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whether it's the RCS, reaction control system,
whether it's the orbital maneuvering system,

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whether it's the aerosurfaces, the SRB actuators,
the solid rocket booster actuators, the main

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propulsion system actuators.

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So you've got sensors, computation and effectors.

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Let me talk a little bit about one sensor
which probably many of you can relate to,

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and that's the IMU or the inertial measurement
unit.

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And Draper Labs is famous for its inertial
measurement units.

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I worked with Draper Labs or MIT Instrumentation
Lab on Apollo, and we had the original initial

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measurement developed by the MIT Instrumentation
Lab in that vehicle.

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The initial measurement unit has gyros on
it to determine angles and it has accelerometers

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on it.

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And it is aligned with the star tracker.

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It's basically a stable platform.

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It's aligned with the star tracker to get
a reference system in inertial space.

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And when you make a maneuver you get acceleration
and you send it to the computer.

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And you integrate it once, you get velocity
and you integrate it twice and you get position.

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And it's also used during powered flight and
it's used during entry but that then goes

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to the computer.

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So the inertial measurement unit is very critical.

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Just to give you an example, here you have
three of them and you have four computers.

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I'm going to talk about the computers in a
minute.

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You have three of them.

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You have to recognize when we went to the
moon on Apollo we had one IMU and one computer

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in the Command and Service Module, and we
had one IMU and one computer in the Lunar

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Module, except we did have a backup system
called a strap-down system.

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The primary system was built by Draper Labs,
MIT, and the backup system was TRW.

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So we had two different contractors.

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Then you have rate gyros and accelerometer
assemblies primarily for ascent, for the stability

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of the bending of the vehicle.

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Here's the air data transducers that we talked
about yesterday for entry.

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Then you have the microwave landing system,
the tactical navigation, radar altimeter,

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rendezvous radar.

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These are all sensors you use during various
phases of a mission, which again go through

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the MDMs or multiplexer demultiplexers to
the computers and then to the effectors which

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change your position and velocity as need
be.

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Let me talk about the computers for a moment.

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You see four computers.

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That was the real test of this system.

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We had four computers that were synchronized.

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This vehicle, as we talked about yesterday,
for aerodynamicists we decided to make it

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statically unstable.

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We saved a lot of weight.

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By that I mean a regular airplane, a normal
airplane that's stable.

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When you get a disturbance it will still come
back.

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Without any augmentation it will come back
to its original position.

224
00:16:43.730 --> 00:16:47.063
With this vehicle, if you get a disturbance
it will diverge.

225
00:16:47.010 --> 00:16:50.150
So you had to continually have augmentation.

226
00:16:50.150 --> 00:16:54.200
So you had to have a fail-operational, fail-safe
system.

227
00:16:54.200 --> 00:16:56.400
And that's why you have four computers.

228
00:16:55.850 --> 00:17:00.880
It's fail -operationa/ fail-safe You could
lose one computer and your fail-operational

229
00:17:00.880 --> 00:17:02.413
will use another computer.

230
00:17:01.690 --> 00:17:03.430
That means you have two left.

231
00:17:03.430 --> 00:17:05.870
And you're fail-safe and you come home.

232
00:17:05.870 --> 00:17:08.339
So that's what it is.

233
00:17:08.339 --> 00:17:12.139
Now, the real concern about it is these computers
are synchronized.

234
00:17:12.089 --> 00:17:16.449
They essentially communicate with each other
440 times a second.

235
00:17:16.449 --> 00:17:21.870
Now, I'm recalling a lot of this from memory,
but 440 times a second.

236
00:17:21.870 --> 00:17:27.249
And they actually vote on each other to simplistic
form terminology.

237
00:17:27.249 --> 00:17:32.049
And if one computer is out, it votes it out
and another computer takes over.

238
00:17:32.049 --> 00:17:33.600
Basically that's it.

239
00:17:33.600 --> 00:17:40.600
But the concern we had was that in doing this
we could have a generic failure and lose all

240
00:17:41.379 --> 00:17:46.850
computers or we could have what we call a
two on two split.

241
00:17:46.850 --> 00:17:51.470
And these would be sort of diabolical errors
which would cause the vehicle to fail.

242
00:17:51.470 --> 00:17:57.820
So we decided, after this was made, to put
in a backup flight system, a backup computer,

243
00:17:57.820 --> 00:17:58.820
a fifth computer.

244
00:17:58.580 --> 00:18:02.090
Now, it turns out there was an argument there.

245
00:18:02.090 --> 00:18:07.090
Should we have the fifth computer a different
computer and different people or should we

246
00:18:07.090 --> 00:18:10.429
have a same computer with different people?

247
00:18:10.429 --> 00:18:13.470
And we argued long and hard on how to do it.

248
00:18:13.470 --> 00:18:16.270
And we had a lot of experience with the Draper
Labs.

249
00:18:15.889 --> 00:18:18.355
The Draper Labs just did an outstanding job.

250
00:18:18.330 --> 00:18:23.796
The MIT Instrumentation Lab just did an outstanding
job on the Apollo vehicle, both on the Command

251
00:18:22.950 --> 00:18:25.016
and Service module and Lunar module.

252
00:18:24.610 --> 00:18:30.659
We went to the MIT Instrumentation Lab, Draper
Labs, and asked them to actually take the

253
00:18:30.659 --> 00:18:34.830
same computer but put it outside the loop.

254
00:18:34.830 --> 00:18:37.419
It's not part of the redundant set.

255
00:18:37.419 --> 00:18:38.720
It's outside the loop.

256
00:18:38.720 --> 00:18:43.320
I didn't show the schematic right because
it gets all the same information that the

257
00:18:42.940 --> 00:18:48.830
other computers get, but it then can take
over if the primary system fails.

258
00:18:48.830 --> 00:18:55.769
Now, Phil Hattis did this work for the Draper
Labs, for NASA in this backup system.

259
00:18:55.769 --> 00:18:57.970
He's going to give you a lecture.

260
00:18:57.970 --> 00:19:00.570
He's very good to lecture on this total system.

261
00:18:59.820 --> 00:19:02.200
He can tell you about the total system.

262
00:19:02.200 --> 00:19:06.866
We thought we'd put the backup flight system
in just for a short period of time to give

263
00:19:05.870 --> 00:19:11.120
us confidence in the primary system, but it
turns out that we started putting things in

264
00:19:11.120 --> 00:19:14.269
it that now we needed so we could not take
it out.

265
00:19:14.269 --> 00:19:16.535
So, it's really part of the major system.

266
00:19:16.389 --> 00:19:21.159
That is a very different part of the system
today.

267
00:19:21.159 --> 00:19:26.419
I don't think we ever really had a diabolical
problem in flight.

268
00:19:26.419 --> 00:19:31.419
I think we did have one in the Shuttle Avionics
Integration Laboratory one time when we had

269
00:19:30.590 --> 00:19:32.230
a two on two split.

270
00:19:32.230 --> 00:19:37.690
But when we did the approach and landing test
where we had the Orbiter on top of the 747

271
00:19:37.690 --> 00:19:42.919
and we separated the Orbiter and landed, I
remember that first flight, I was sitting

272
00:19:42.919 --> 00:19:47.870
in the Control Station at Edwards Air Force
Base, and at that time I smoked a pipe, and

273
00:19:47.870 --> 00:19:52.889
when we separated a big X came across the
screen because we lost the first computer.

274
00:19:52.889 --> 00:19:57.049
I guess the shock actually broke a solder
joint in the computer.

275
00:19:57.049 --> 00:20:02.019
The power shock from separating actually broke
the first computer so we had to go to the

276
00:20:02.019 --> 00:20:03.019
second computer.

277
00:20:02.590 --> 00:20:03.840
I bit my pipe in two.

278
00:20:03.840 --> 00:20:09.159
But it did prove that the redundant set did
work because it took over and landed.

279
00:20:09.159 --> 00:20:16.159
We had a very successful in-flight test, not
planned, but it turned out to be a very successful

280
00:20:16.340 --> 00:20:19.580
in-flight test.

281
00:20:19.580 --> 00:20:26.580
Now, when you make the computations, you get
the information on position that the computer

282
00:20:26.730 --> 00:20:33.730
computes, it sends it to 
the effectors.

283
00:20:38.529 --> 00:20:43.395
The effectors, during the high part of entry,
may be to the reaction control system, the

284
00:20:43.179 --> 00:20:50.179
forward RCS system or to the aft, or it could
be to the OMS systems if you're trying to

285
00:20:50.389 --> 00:20:51.440
make a maneuver.

286
00:20:51.440 --> 00:20:57.559
Or, when you get down lower in the atmosphere,
it could be the aerosurface actuators.

287
00:20:57.559 --> 00:21:02.820
And then, during ascent, it's to the solid
rocket boosters or the main propulsion system.

288
00:21:02.820 --> 00:21:04.960
So, those are the effectors.

289
00:21:04.960 --> 00:21:11.799
The flight control system is a very interesting
system for entry because, as you can envision

290
00:21:11.799 --> 00:21:18.610
early in the entry you don't have any aerodynamics
so your aerosurfaces aren't of any value to

291
00:21:18.610 --> 00:21:20.943
you, you use the reaction control system.

292
00:21:20.450 --> 00:21:25.250
But, as you get farther into the atmosphere,
the loads become so high that the reaction

293
00:21:25.200 --> 00:21:29.600
control system becomes ineffective and then
you have to use the aerosurfaces.

294
00:21:28.279 --> 00:21:30.129
So it's a blended system.

295
00:21:30.129 --> 00:21:35.820
And the system has to know when to handle
the aerosurfaces versus the reaction control

296
00:21:35.820 --> 00:21:36.286
system.

297
00:21:36.090 --> 00:21:43.080
And, of course, then you also have displays
to the crew and actually information that

298
00:21:43.080 --> 00:21:45.850
the crew could use to make certain decisions.

299
00:21:45.850 --> 00:21:50.279
So that basically is the guidance, navigation
and control system.

300
00:21:50.279 --> 00:21:55.619
There is one additional change, that I don't
have on this chart, which they have incorporated

301
00:21:55.619 --> 00:21:58.509
the global positioning system in the shuttle.

302
00:21:58.509 --> 00:22:01.860
The GPS is now part of the system.

303
00:22:01.860 --> 00:22:07.119
It took a long time to do it because I remember
it wasn't done when I left.

304
00:22:07.119 --> 00:22:10.779
And were you still there when it was implemented?

305
00:22:10.779 --> 00:22:13.480
Yeah, they did put it in.

306
00:22:13.480 --> 00:22:18.840
And GPS you can essentially get position.

307
00:22:18.840 --> 00:22:25.840
If you could get attitude then theoretically
you could eliminate the inertial measurement.

308
00:22:27.659 --> 00:22:29.659
And I don't think they do it that way.

309
00:22:29.360 --> 00:22:36.360
But theoretically, the GPS, for you looking
at the guidance system change, this again

310
00:22:37.159 --> 00:22:41.639
becomes a very interesting system to look
at.

311
00:22:41.639 --> 00:22:43.439
Would you do it different today?

312
00:22:42.860 --> 00:22:49.860
For example, the computer that was used, I
cannot remember all the characteristics of

313
00:22:52.570 --> 00:22:56.636
it, but it's basically the IBM 4 Pi computer,
which is a very old computer.

314
00:22:55.899 --> 00:22:59.629
It was probably made before many of you were
using computers.

315
00:22:59.629 --> 00:23:00.679
Or, weren't born.

316
00:23:00.679 --> 00:23:06.769
[OVERLAPPING VOICES] which I think was a design
from the early `70s.

317
00:23:06.769 --> 00:23:09.799
Yeah, it is the early `70s.

318
00:23:09.799 --> 00:23:14.690
This would be a very neat system to take a
look at for your system.

319
00:23:14.690 --> 00:23:19.290
Not only that, you could probably get a lot
of support from Draper Labs and that type

320
00:23:17.299 --> 00:23:17.832
of thing.

321
00:23:17.690 --> 00:23:20.490
So it would really be a good system to take
a look at.

322
00:23:19.539 --> 00:23:22.272
And I'm sure you could make a lot of improvements.

323
00:23:21.860 --> 00:23:28.860
Those improvements could theoretically be
used on the new CEV, the crew exploration

324
00:23:28.899 --> 00:23:29.759
vehicle.

325
00:23:29.759 --> 00:23:36.179
I think it would land a lot of merit of you
very smart people to take a look at the guidance,

326
00:23:36.179 --> 00:23:37.979
navigation and control system.

327
00:23:37.269 --> 00:23:37.929
Yes, sir.

328
00:23:37.929 --> 00:23:43.470
In the air data transducers, were there more
than just torpedo tubes and static cords?

329
00:23:43.470 --> 00:23:45.270
That's all there was, I believe.

330
00:23:44.879 --> 00:23:46.440
I think that was.

331
00:23:46.440 --> 00:23:48.373
We had a lot of problems with those.

332
00:23:47.419 --> 00:23:50.200
I think it's just very old technology.

333
00:23:50.200 --> 00:23:51.320
Yes.

334
00:23:51.320 --> 00:23:58.320
I was going to ask, how you got position information
before GPS.

335
00:24:04.769 --> 00:24:05.369
Position?

336
00:24:05.360 --> 00:24:08.309
Well, I don't know exactly.

337
00:24:08.309 --> 00:24:12.009
But it's got 13 satellites going around.

338
00:24:12.009 --> 00:24:15.149
Well, there were two ways.

339
00:24:15.149 --> 00:24:20.590
I mean the desire for GPS, of course, was
to give the shuttle autonomous navigation

340
00:24:20.590 --> 00:24:22.049
capability.

341
00:24:22.049 --> 00:24:28.549
The shuttle with the star trackers and the
IMUs, it has the autonomous ability to determine

342
00:24:28.549 --> 00:24:33.282
its attitude, but it doesn't know where it
is because the inertial measurement units

343
00:24:32.989 --> 00:24:34.799
drift over time.

344
00:24:34.799 --> 00:24:38.980
And so you need to be able to update the state
vectors.

345
00:24:38.980 --> 00:24:43.600
Originally, the only way you could do it was
radar tracking from the ground.

346
00:24:43.600 --> 00:24:44.989
You would track it.

347
00:24:44.989 --> 00:24:46.589
You would get a state vector.

348
00:24:46.139 --> 00:24:50.472
You would uplink the state vector and then
the shuttle would know where it was.

349
00:24:49.450 --> 00:24:53.950
And then periodically you would have to update
it because of IMU drift.

350
00:24:53.950 --> 00:25:00.950
Once we got the tracking and data relay satellite
system installed, you do get navigational

351
00:25:03.039 --> 00:25:09.419
information by the Doppler navigation and
from the signals coming back and forth through

352
00:25:09.419 --> 00:25:12.549
TDRSS, but it was generally calculated on
the ground.

353
00:25:12.549 --> 00:25:19.549
So it was not really until the advent of GPS
that we got autonomous capability.

354
00:25:21.070 --> 00:25:26.929
You need it for things like if you're going
to deploy a satellite, for instance, you need

355
00:25:26.929 --> 00:25:31.369
to know your position pretty accurately.

356
00:25:31.369 --> 00:25:36.580
Because the satellite is going to take that
position and has to do its burn accordingly.

357
00:25:36.580 --> 00:25:43.580
And, obviously, for your reentry burn or for
rendezvous it's critical that you know your

358
00:25:44.600 --> 00:25:45.509
position.

359
00:25:45.509 --> 00:25:49.642
When you're doing a rendezvous, the shuttle
does have a rendezvous radar.

360
00:25:49.169 --> 00:25:52.779
I don't know if we'll deal with that in detail.

361
00:25:52.779 --> 00:25:57.830
Once you get close enough to the object that
you're rendezvousing with such that you can

362
00:25:57.830 --> 00:26:02.896
get it either with your radar, or they actually
use the star trackers to optically track the

363
00:26:02.559 --> 00:26:07.625
object, then you can start getting your relative
position with respect to the object, Even

364
00:26:07.440 --> 00:26:10.179
though you may not know your absolute position.

365
00:26:10.179 --> 00:26:14.860
And so, from that point of view, the shuttle
gets a certain degree of autonomy.

366
00:26:14.860 --> 00:26:21.230
Maybe I'll just say one other thing about
the computers because people are amazed at

367
00:26:21.230 --> 00:26:23.710
how primitive the shuttle computers are.

368
00:26:23.710 --> 00:26:29.049
But, like I say, the original idea and the
concepts that we talked about, this was going

369
00:26:29.049 --> 00:26:31.860
to be an airplane-like vehicle.

370
00:26:31.860 --> 00:26:35.749
And originally they wanted to use some off-the-shelf
hardware.

371
00:26:35.749 --> 00:26:41.179
And, of course, the AP-101s, as they finally
used them, were not off the shelf.

372
00:26:41.179 --> 00:26:48.179
But these original computers had 128k of memory.

373
00:26:48.499 --> 00:26:53.850
And the memory they used, I don't know if
any of you have read back in the history of

374
00:26:53.850 --> 00:26:59.183
computing where they actually had the little
magnetic ring cores with the wires going through.

375
00:26:58.309 --> 00:27:00.489
I mean this was really old stuff.

376
00:27:00.489 --> 00:27:06.299
And they did finally replace that with a solid-state
memory with a whopping 256k.

377
00:27:06.299 --> 00:27:13.299
And, again, probably none of you have dealt
with overlay technology but, back when I was

378
00:27:13.649 --> 00:27:19.789
a graduate student and we were using computers
to do complex astrophysical calculations,

379
00:27:19.789 --> 00:27:25.659
sometimes you would have a program that was
too big for the computer memory so you would

380
00:27:25.659 --> 00:27:30.450
have the whole program on a tape recorder
and you'd segment it into what they would

381
00:27:30.450 --> 00:27:31.316
call overlays.

382
00:27:31.269 --> 00:27:35.469
And then you would load it one part at a time
and it would do its calculations.

383
00:27:34.940 --> 00:27:38.539
And then you would stop and load the next
batch of software.

384
00:27:38.539 --> 00:27:41.005
Well, that's the way we have to run a mission.

385
00:27:40.700 --> 00:27:47.149
The computers cannot hold enough software
to do ascent, orbit and entry.

386
00:27:47.149 --> 00:27:50.149
There are three segments of flight software.

387
00:27:50.149 --> 00:27:53.299
You start the mission with the ascent software
loaded.

388
00:27:53.299 --> 00:27:58.409
Then, when you get up into orbit, you do what
they call a major mode transition where you

389
00:27:58.409 --> 00:28:02.369
basically punch a button and everything goes
blank.

390
00:28:02.369 --> 00:28:06.700
And you sort of sit there saying I hope this
is going to load properly.

391
00:28:06.700 --> 00:28:11.379
And the tape recorder chugs away.

392
00:28:11.379 --> 00:28:13.779
And then it loads the orbit part.

393
00:28:13.779 --> 00:28:16.845
And the same thing when you're getting ready
for entry.

394
00:28:15.999 --> 00:28:21.019
Now, the backup system they decided that they
didn't want to take that risk.

395
00:28:21.019 --> 00:28:27.419
That if something went wrong in a major way
they wanted the whole flight software on the

396
00:28:27.419 --> 00:28:28.285
backup system.

397
00:28:27.830 --> 00:28:30.489
And that meant it had to be scrubbed.

398
00:28:30.489 --> 00:28:36.289
The backup system is capable of flying the
shuttle and getting it home safely, but there

399
00:28:36.289 --> 00:28:43.289
are a lot of capabilities which the main computer
system can do which the backup system cannot

400
00:28:43.899 --> 00:28:47.869
do just because they're limited to the amount
of software.

401
00:28:47.869 --> 00:28:54.869
The one other thing I'll say is putting together
this redundant set of four computers because,

402
00:28:55.590 --> 00:28:59.690
as Professor Cohen said, the shuttle will
not fly without the computers.

403
00:28:59.690 --> 00:29:02.840
I mean it's absolutely flight critical.

404
00:29:02.840 --> 00:29:09.840
Hundreds of times a second, every computer
is looking at the data from all the other

405
00:29:10.440 --> 00:29:11.106
computers.

406
00:29:11.100 --> 00:29:13.090
And they are all voting.

407
00:29:13.090 --> 00:29:19.830
And so you have this matrix, just to make
sure you understand the way the system works.

408
00:29:19.830 --> 00:29:26.659
If computer number one sees a problem with
computer number three, it's likely that computer

409
00:29:26.659 --> 00:29:33.059
three is also going to see a problem with
computer one because they're doing something

410
00:29:33.059 --> 00:29:33.749
different.

411
00:29:33.749 --> 00:29:38.749
But if computer number two sees a problem
with computer three and computer three sees

412
00:29:38.749 --> 00:29:43.882
a problem with computer two and computer four
sees a problem with computer three, now you've

413
00:29:43.119 --> 00:29:44.889
got a three to one vote.

414
00:29:44.889 --> 00:29:51.889
And so computer three will recognize that
it is the problem and it will take itself

415
00:29:53.539 --> 00:29:54.850
out of the set.

416
00:29:54.850 --> 00:29:59.250
And that's what happened, well, in that case,
the computer actually shut down.

417
00:29:58.409 --> 00:30:00.210
I remember that big X.

418
00:30:00.210 --> 00:30:03.450
I bit my pipe in two.

419
00:30:03.450 --> 00:30:09.710
And, at the same time, all of this information
has to go back and forth to the backup computer.

420
00:30:09.710 --> 00:30:14.310
Because, if you're ever going to engage the
backup computer, it has to be ready to go

421
00:30:14.119 --> 00:30:17.139
at a split second's notice.

422
00:30:17.139 --> 00:30:24.139
And there are situations where you can get
a two on two split.

423
00:30:26.749 --> 00:30:32.940
When we run through the simulations to learn
how to work this, actually learning the ins

424
00:30:32.940 --> 00:30:39.119
and outs of how to work the computer system
is probably one of the biggest trainings.

425
00:30:39.119 --> 00:30:42.652
The astronauts become more knowledgeable than
the designers.

426
00:30:42.159 --> 00:30:42.460
Yes?

427
00:30:42.460 --> 00:30:49.460
If there is this danger of a two to two vote,
was it ever thought about to have five computers

428
00:30:52.080 --> 00:30:52.413
then?

429
00:30:52.320 --> 00:30:54.786
Well, that's why we put the backup system
in.

430
00:30:54.450 --> 00:30:55.989
Oh, the backup system.

431
00:30:55.989 --> 00:30:57.389
Yeah, the backup system.

432
00:30:56.929 --> 00:30:59.820
That was why we put the backup system in.

433
00:30:59.820 --> 00:31:02.649
It did a little bit more, too.

434
00:31:02.649 --> 00:31:04.849
It was programmed by different people.

435
00:31:04.119 --> 00:31:08.785
Even though it used the same computer, it
was actually programmed and formulated by

436
00:31:08.739 --> 00:31:09.805
different people.

437
00:31:09.739 --> 00:31:15.869
So, that was one way of saying take away any,
you might say, systematic errors that were

438
00:31:15.869 --> 00:31:17.069
in the redundant set.

439
00:31:16.749 --> 00:31:23.669
In other words, they kept the same software
requirements document but the actual coding

440
00:31:23.669 --> 00:31:26.960
was done by Draper rather than by IBM.

441
00:31:26.960 --> 00:31:28.570
That was the other problem.

442
00:31:28.570 --> 00:31:34.369
Suppose all four computers are doing the same
thing but there was an error in the code which

443
00:31:34.369 --> 00:31:41.039
never turned out so that something starts
to diverge, what's your protection against

444
00:31:41.039 --> 00:31:41.372
that?

445
00:31:41.149 --> 00:31:44.919
There was a big argument in doing that.

446
00:31:44.919 --> 00:31:49.119
The real argument said should you really have
this or a different computer?

447
00:31:48.539 --> 00:31:51.872
Should you really just say just do everything
differently?

448
00:31:50.359 --> 00:31:52.159
Just have a different computer?

449
00:31:51.590 --> 00:31:52.990
A different everything?

450
00:31:52.419 --> 00:31:56.952
And, of course, there are advantages to that
and there are disadvantages to that.

451
00:31:56.710 --> 00:32:00.070
So, we settled on this.

452
00:32:00.070 --> 00:32:02.070
I think there was another question.

453
00:32:00.529 --> 00:32:02.329
Was there a question back there?

454
00:32:01.549 --> 00:32:01.850
Yes?

455
00:32:01.850 --> 00:32:04.679
You said this was the first fly-by-wire system.

456
00:32:04.679 --> 00:32:11.679
I was wondering what competing ideas there
were besides having [four computer systems?].

457
00:32:13.850 --> 00:32:20.850
Well, fly-by-wire means when you put an input
into the control system, whether you do it

458
00:32:21.330 --> 00:32:28.330
manually or whether the computer does it,
nevertheless, ultimately your command just

459
00:32:28.700 --> 00:32:30.649
goes into the computer.

460
00:32:30.649 --> 00:32:37.649
You put the stick to the left saying I want
to do a left bank, all you're doing is telling

461
00:32:37.659 --> 00:32:39.792
the computer you want to do a left bank.

462
00:32:39.739 --> 00:32:46.220
And now the computer has to figure out what's
my navigation state, where am I if I'm coming

463
00:32:46.220 --> 00:32:52.679
down through the atmosphere, what's my altitude,
what's the air pressure, what's my mach number?

464
00:32:52.679 --> 00:32:56.809
And then it's programmed with aerodynamic
control laws.

465
00:32:56.809 --> 00:32:58.960
This is one of the big challenges.

466
00:32:58.960 --> 00:33:05.960
Because, as I mentioned the other day, you
hit the top of the atmosphere at mach 25,

467
00:33:05.960 --> 00:33:09.769
you do your initial control with the RCS.

468
00:33:09.769 --> 00:33:16.769
As the dynamic pressure starts to increase,
first the ailerons, the roll becomes active

469
00:33:19.239 --> 00:33:25.549
at about, I think, ten pounds per square inch,
something like that.

470
00:33:25.549 --> 00:33:29.369
You blend the roll control into your aerosurfaces.

471
00:33:29.369 --> 00:33:34.869
At about 20, I think it's pounds per square
inch, you can do the pitch control.

472
00:33:34.869 --> 00:33:40.999
But because the shuttle is coming in at a
40 degree angle, the vertical stabilizer is

473
00:33:40.999 --> 00:33:44.049
pretty much shadowed.

474
00:33:44.049 --> 00:33:50.049
So for yaw control you actually have to keep
using the RCS all the way down to about mach

475
00:33:50.049 --> 00:33:55.479
one when the shuttle finally pitches down
and the vertical stabilizer now has some effectivity.

476
00:33:55.479 --> 00:34:02.479
The computer calculates all this information
and it comes to the effectors, and you do

477
00:34:06.159 --> 00:34:07.559
the control laws on that.

478
00:34:07.460 --> 00:34:14.409
And the problem is that the flight control
laws, which the computer has to use in order

479
00:34:14.409 --> 00:34:19.480
to control the air surfaces in the RCS, are
not constant on your way down.

480
00:34:19.480 --> 00:34:26.480
I mean the flight control laws at mach 15
are very different from at mach 5.

481
00:34:28.659 --> 00:34:34.869
And there is part of the flight regime, for
instance, where if you want do a left bank,

482
00:34:34.869 --> 00:34:38.649
you actually have to start by commanding a
right yaw.

483
00:34:38.649 --> 00:34:45.649
And then the cross-coupling terms in the aerodynamics
actually causes you to go in the other direction.

484
00:34:46.020 --> 00:34:47.220
It gets very complex.

485
00:34:46.970 --> 00:34:53.639
And the flight control system is continually
changing as the entry progresses.

486
00:34:53.639 --> 00:35:00.639
And so the idea that maybe you should have
a direct backup link between the pilot's inputs

487
00:35:03.339 --> 00:35:10.339
and the aerocontrol surfaces, although it
might give you a warm, fuzzy feeling, you

488
00:35:10.400 --> 00:35:12.859
could not fly the shuttle directly.

489
00:35:12.859 --> 00:35:19.549
Because to be able to take into account these
change in control laws on the way down, you

490
00:35:19.549 --> 00:35:20.549
just cannot do it.

491
00:35:20.520 --> 00:35:26.200
In fact, the shuttle is uniquely, I mean,
unless the shuttle knows where it is, if the

492
00:35:26.200 --> 00:35:31.780
navigation state goes bad the shuttle cannot
fly.

493
00:35:31.780 --> 00:35:38.780
You could have the runway in sight, but if
the shuttle's inertial nav state is wrong

494
00:35:39.349 --> 00:35:41.682
you will lose control and you cannot land.

495
00:35:41.180 --> 00:35:45.130
So it's a very complex system from that point
of view.

496
00:35:45.130 --> 00:35:49.796
This is a very, very, if you can envision
the systems engineering that went into this

497
00:35:49.260 --> 00:35:56.260
system, it takes aeordynamics, it takes flight
dynamics, it takes electrical signals, it

498
00:35:56.460 --> 00:36:01.339
takes guidance laws, navigation laws, hardware,
software.

499
00:36:01.339 --> 00:36:07.690
This is probably the biggest integration job,
or systems engineering job.

500
00:36:07.690 --> 00:36:09.170
It requires everything.

501
00:36:09.170 --> 00:36:12.570
It also has to take into consideration aerodynamic
heating.

502
00:36:12.400 --> 00:36:17.533
I'm going to show you that in a minute, because
you've got to be sure that you don't fly outside

503
00:36:15.369 --> 00:36:18.502
the regime that you were designed for aerodynamically.

504
00:36:17.990 --> 00:36:19.456
I think you had a question.

505
00:36:19.230 --> 00:36:21.460
Just real quick, how big are those IMUs?

506
00:36:21.460 --> 00:36:25.960
Because nowadays you can get a solid-state
one not quite that big.

507
00:36:25.960 --> 00:36:27.210
Well, I don't recall.

508
00:36:27.210 --> 00:36:29.230
It's a box, sort of like a shoebox.

509
00:36:29.230 --> 00:36:31.640
The Apollo IMU was about this big.

510
00:36:31.640 --> 00:36:33.840
That was built for the Polaris vehicle.

511
00:36:33.170 --> 00:36:36.660
It was one IMU and it was a three gimble platform.

512
00:36:36.660 --> 00:36:39.500
And I remember it was a big issue.

513
00:36:39.500 --> 00:36:44.166
A three gimble platform has a singularity,
so you had to maneuver the Apollo vehicle

514
00:36:44.160 --> 00:36:47.160
a certain way so you didn't get the singularity
in it.

515
00:36:47.160 --> 00:36:52.093
And one of our astronauts, Jim McDivitt, quite
a famous astronaut who was a good friend of

516
00:36:51.829 --> 00:36:54.619
mine, said he wanted a fourth gimble.

517
00:36:54.619 --> 00:36:58.885
And there was no way we could get an IMU in
that day in time with a fourth gimble.

518
00:36:58.609 --> 00:37:02.609
So, what I did was gave him a fourth gimble
to carry with him on his flight.

519
00:37:02.349 --> 00:37:05.440
A little gimble system so he had a fourth
gimble.

520
00:37:05.440 --> 00:37:10.506
We didn't have the gimble lock problem on
the shuttle because it was a four gimble platform.

521
00:37:09.520 --> 00:37:14.386
But I remember we went through that with MIT
Instrumentation many times because all you

522
00:37:13.890 --> 00:37:19.369
could get at that time, because the IMUs were
so big, a fourth gimble was almost impossible.

523
00:37:19.369 --> 00:37:23.235
And McDivitt was a very good astronaut but
he wanted the four gimbles.

524
00:37:22.980 --> 00:37:24.846
In fact, he wound up being my boss.

525
00:37:24.700 --> 00:37:30.940
Before we go on, let me just mention one more
thing about the backup system.

526
00:37:30.940 --> 00:37:31.299
Sure.

527
00:37:31.299 --> 00:37:32.030
Go ahead.

528
00:37:32.030 --> 00:37:36.563
The backup system actually takes a lot of
care and maintenance and there's a lot of

529
00:37:36.400 --> 00:37:38.640
money that goes into that.

530
00:37:38.640 --> 00:37:43.173
And this is not a dead issue because in the
design of the CEV, NASA is going to have to

531
00:37:42.940 --> 00:37:45.599
make a decision.

532
00:37:45.599 --> 00:37:50.732
There were some guidelines which were produced
a couple of years ago out of the Johnson Space

533
00:37:50.010 --> 00:37:55.190
Center with a lot of astronaut office input
about what are the requirements in the future

534
00:37:55.190 --> 00:37:58.589
for human space vehicles?

535
00:37:58.589 --> 00:38:03.589
And they put in that you should have a backup
computer system because basically that's the

536
00:38:03.549 --> 00:38:04.815
way we did the shuttle.

537
00:38:04.799 --> 00:38:07.750
And, actually, that was an afterthought.

538
00:38:07.750 --> 00:38:10.930
And yet now it's being listed as a requirement.

539
00:38:10.930 --> 00:38:17.930
And this is now being questioned for the CEV
because it's a huge financial impact.

540
00:38:18.650 --> 00:38:22.930
And so we're going to have to deal with these
problems all over again.

541
00:38:22.930 --> 00:38:27.596
It's an interesting thing to think about if
some of you want to delve a little bit more

542
00:38:26.000 --> 00:38:26.480
deeply.

543
00:38:26.480 --> 00:38:30.780
I think this could lead to a very interesting
activity for you.

544
00:38:30.780 --> 00:38:31.460
Yes, sir.

545
00:38:31.460 --> 00:38:35.860
Do backup computers have their own sensor
or are they reading the same sensors?

546
00:38:35.710 --> 00:38:36.710
The same sensors.

547
00:38:35.780 --> 00:38:41.539
I just didn't show this very accurately because
I looked at the chart, when I had it, I said

548
00:38:41.539 --> 00:38:43.205
my God this is the wrong chart.

549
00:38:42.920 --> 00:38:47.586
But this was the original chart before the
backup system so I quickly penciled in the

550
00:38:46.900 --> 00:38:49.700
backup system so I would remember to talk
about it.

551
00:38:48.369 --> 00:38:50.169
But, no, it has the same sensors.

552
00:38:49.609 --> 00:38:51.409
It has all the same information.

553
00:38:50.869 --> 00:38:53.602
But, again, most of those sensors are redundant.

554
00:38:52.460 --> 00:38:54.393
Yeah, they're redundant sensors.

555
00:38:54.380 --> 00:38:56.113
Not all of them but most of them.

556
00:38:55.609 --> 00:38:58.875
Any one of the four computers can read any
of these sensors.

557
00:38:58.490 --> 00:39:01.756
It's not like sensor one is dedicated [to
this computer?].

558
00:39:01.750 --> 00:39:06.059
The sensor input is put on a data bus, and
they have multiple data buses.

559
00:39:06.059 --> 00:39:10.125
Like four data buses in each of the computers
can read all four data buses.

560
00:39:10.000 --> 00:39:13.533
I mean there's just a tremendous amount of
redundancy built in.

561
00:39:13.270 --> 00:39:14.070
Yes, go ahead.

562
00:39:13.869 --> 00:39:18.450
Did they ever use the star tracker to update
your gyros?

563
00:39:18.450 --> 00:39:19.250
The platform?

564
00:39:18.990 --> 00:39:20.920
Yeah, they do that.

565
00:39:20.920 --> 00:39:26.520
There is also a procedure if you totally lose
attitude.

566
00:39:26.520 --> 00:39:31.640
Then you have to go right back and manually
take a star site and orient.

567
00:39:31.640 --> 00:39:37.119
And that we've only had to do in a simulator.

568
00:39:37.119 --> 00:39:40.950
To look at the failure history of this would
be very interesting.

569
00:39:40.950 --> 00:39:44.740
In my tenure, I know we lost one inertial
measurement unit.

570
00:39:44.740 --> 00:39:48.680
We lost that one computer during the approach
and landing test.

571
00:39:48.680 --> 00:39:53.720
I don't know what other failures we actually
had in this system.

572
00:39:53.720 --> 00:39:57.520
The MDMs, this box was made by Sperry at the
time in Phoenix, Arizona.

573
00:39:57.520 --> 00:40:04.520
And I've visited that many times because that
is probably the most complicated electronics

574
00:40:04.549 --> 00:40:07.282
box of this whole system other than the computer.

575
00:40:06.710 --> 00:40:08.376
It's very, very complicated.

576
00:40:06.829 --> 00:40:07.362
Yes, sir.

577
00:40:06.900 --> 00:40:13.900
Computers have developed a lot faster so why
do you still think that it will be a major

578
00:40:19.970 --> 00:40:20.703
expense now?

579
00:40:20.700 --> 00:40:23.910
I don't think it will be a major expense now.

580
00:40:23.910 --> 00:40:29.130
As I recall, and you're absolutely right,
NASA does not put a lot of money into development

581
00:40:29.130 --> 00:40:32.180
of this technology because other people have
done it.

582
00:40:32.180 --> 00:40:35.309
It's so much more sophisticated than we have
now.

583
00:40:35.309 --> 00:40:37.390
We don't need it.

584
00:40:37.390 --> 00:40:43.849
It turns out, though, at one point in time
structures was the most expensive component

585
00:40:43.849 --> 00:40:45.680
of a space craft.

586
00:40:45.680 --> 00:40:47.950
Then, of course, there was propulsion.

587
00:40:47.950 --> 00:40:50.483
And then there became avionics and software.

588
00:40:49.940 --> 00:40:53.673
And avionics and software for the shuttle
is very, very expensive.

589
00:40:52.779 --> 00:40:55.445
It's probably one of the most expensive things.

590
00:40:54.539 --> 00:41:01.539
I think today, in today's environment, with
the technology we have in both software and

591
00:41:01.740 --> 00:41:04.740
hardware, I think it won't be that expensive
anymore.

592
00:41:04.690 --> 00:41:07.650
So, I think you're right.

593
00:41:07.650 --> 00:41:13.230
That's why I'm saying in redoing it, you could
use new technology and really show how much

594
00:41:13.230 --> 00:41:17.363
less it's going to weigh because the IMUs
are probably going to be smaller.

595
00:41:16.630 --> 00:41:21.563
You could reduce the weight, you could reduce
the electric power and you could reduce the

596
00:41:19.710 --> 00:41:23.039
cost.

597
00:41:23.039 --> 00:41:26.372
But you're going to have another detailed
briefing on this.

598
00:41:24.859 --> 00:41:31.329
And Phil Hattis, I know him very well, I think
he will do an outstanding job in explaining

599
00:41:31.329 --> 00:41:32.420
it to you.

600
00:41:32.420 --> 00:41:37.220
Let me just show you very briefly, we talked
a little bit about this yesterday, but here

601
00:41:36.240 --> 00:41:41.980
are some of the profiles that the guidance
system has to be able to do.

602
00:41:41.980 --> 00:41:45.529
It certainly has to take care of launch.

603
00:41:45.529 --> 00:41:50.619
The abort modes, which are interesting, there
is an abort mode that is a return to launch

604
00:41:50.619 --> 00:41:52.010
site.

605
00:41:52.010 --> 00:41:56.610
And I guess you would use return to launch
site primarily for a main engine failure,

606
00:41:55.510 --> 00:41:56.089
I guess.

607
00:41:56.089 --> 00:42:00.690
If the main engine fails during ascent, you
can go to a return to launch site.

608
00:42:00.690 --> 00:42:04.223
Or, a total loss of cabin pressurization,
something like that.

609
00:42:04.029 --> 00:42:06.029
And I guess that's never been tried.

610
00:42:05.390 --> 00:42:10.256
And I guess that's probably one of the most
difficult maneuvers, most biggest fears the

611
00:42:09.079 --> 00:42:13.012
astronauts have if they ever have to come
back to return to launch site.

612
00:42:11.990 --> 00:42:16.256
But, of course, the guidance system has got
to be capable to take care of that.

613
00:42:15.460 --> 00:42:22.460
Then you have 
abort once around.

614
00:42:23.200 --> 00:42:28.510
Again, when you have main engine cutoff, you
have separation and you abort to once around.

615
00:42:28.510 --> 00:42:32.069
Again, I guess that's primarily a main engine
problem.

616
00:42:32.069 --> 00:42:35.970
And then you have, of course, an abort to
orbit.

617
00:42:35.970 --> 00:42:38.570
And those are the three abort regimes you
have.

618
00:42:38.029 --> 00:42:38.562
Yes, sir.

619
00:42:38.029 --> 00:42:39.429
Transatlantic landing?

620
00:42:38.029 --> 00:42:38.962
Transatlantic.

621
00:42:38.029 --> 00:42:40.029
Yes, you have transatlantic abort.

622
00:42:38.299 --> 00:42:39.160
That's right.

623
00:42:39.160 --> 00:42:42.839
You do have transatlantic abort.

624
00:42:42.839 --> 00:42:45.049
Yes, thank you.

625
00:42:45.049 --> 00:42:51.420
That actually drives the launch window, because
[if they don't have clear weather overseas

626
00:42:51.420 --> 00:42:53.099
they don't launch?] .

627
00:42:53.099 --> 00:42:54.220
That's right.

628
00:42:54.220 --> 00:43:00.940
So, the guidance system has to take care of
all those abort modes.

629
00:43:00.940 --> 00:43:05.940
Again, I'm sure Phil will go through this
with you.

630
00:43:05.940 --> 00:43:12.940
But first stage guidance really consists of
attitude and throttle schedules as a function

631
00:43:14.309 --> 00:43:15.575
of relative velocity.

632
00:43:15.339 --> 00:43:20.139
It's not completely open-loop, it's almost
an open-looped system, but you do control

633
00:43:19.099 --> 00:43:24.650
the thrust vectors of the engine and the solid
rocket booster actuators.

634
00:43:24.650 --> 00:43:31.650
And the key thing, though, where systems engineering
comes into play, it has to get maximum performance.

635
00:43:33.410 --> 00:43:40.410
But the angle tack history has got to be shaped
to control aerodynamic loads.

636
00:43:40.529 --> 00:43:45.490
Because some of the highest loads you have,
and you will find out when Moser talks about

637
00:43:45.490 --> 00:43:49.549
it, some of the highest loads you have on
the structure is during ascent.

638
00:43:49.549 --> 00:43:51.682
Control of maximum dynamic pressure.

639
00:43:51.210 --> 00:43:55.876
And you have to provide the flight angle at
SRB staging to allow recovery of the spent

640
00:43:55.630 --> 00:43:56.520
boosters.

641
00:43:56.520 --> 00:43:59.186
These are some of the constraints that you
have.

642
00:43:58.940 --> 00:44:02.740
And, again, this comes out to be a real systems
engineering problem.

643
00:44:02.319 --> 00:44:09.319
And for entry, entry really becomes a task
in itself because one of the basic problems

644
00:44:13.789 --> 00:44:16.650
you have to control is thermal control.

645
00:44:16.650 --> 00:44:23.650
The thermal protection system, I should have
pointed out on that structural slide that

646
00:44:23.849 --> 00:44:29.559
the back face temperature of the tiles have
to be at 350 degrees Fahrenheit.

647
00:44:29.559 --> 00:44:34.225
While the surface temperature may be 15 to
2000 degrees Fahrenheit the back face has

648
00:44:34.020 --> 00:44:40.660
to be at 350 degrees Fahrenheit because that's
the limit of aluminum, so you've got to control

649
00:44:40.660 --> 00:44:42.450
the guidance.

650
00:44:42.450 --> 00:44:47.583
The thermal control for guidance is to keep
the vehicle within the temperature constraints

651
00:44:46.750 --> 00:44:48.283
in the peak heating region.

652
00:44:47.799 --> 00:44:52.930
So, that's all got to be married together
so that the tile system you design keeps the

653
00:44:52.930 --> 00:44:59.039
back face temperature to within 350 degrees
on the aluminum structure.

654
00:44:59.039 --> 00:45:02.339
Then you go into equilibrium glide.

655
00:45:02.339 --> 00:45:06.539
Constant bank angle, we were talking about,
is modulated for drag control.

656
00:45:05.510 --> 00:45:10.310
And then the transition guides the vehicle
from the high out braking to the lower angle

657
00:45:09.230 --> 00:45:10.900
of attack.

658
00:45:10.900 --> 00:45:12.819
And then you basically land.

659
00:45:12.819 --> 00:45:19.410
All this has to be tied together for your
guidance, navigation and control system.

660
00:45:19.410 --> 00:45:24.980
I have one more system that I'd like to talk
about briefly.

661
00:45:24.980 --> 00:45:28.646
Now, you're going to have another very detailed
briefing on this.

662
00:45:28.210 --> 00:45:31.599
This is the hydraulic system.

663
00:45:31.599 --> 00:45:38.599
This ties in together with the other systems
we talked about, the flight control system,

664
00:45:40.220 --> 00:45:45.486
the guidance system, the Department of Flight
Control, because the hydraulic system is three

665
00:45:44.520 --> 00:45:45.069
systems.

666
00:45:45.069 --> 00:45:48.450
It's a 3000 pound per square inch system.

667
00:45:48.450 --> 00:45:51.430
And what does it do?

668
00:45:51.430 --> 00:45:58.140
It basically is used during ascent and entry
for it to control the thrust vector control

669
00:45:58.140 --> 00:46:05.140
of the engines, for the body flap, for the
elevons, for the rudder speed brake, the actuators

670
00:46:06.279 --> 00:46:13.279
for the main engine, the doors for the external
tank separation, main landing gear, nose wheel

671
00:46:15.980 --> 00:46:18.470
steering and braking.

672
00:46:18.470 --> 00:46:21.079
So, that's what the hydraulic system does.

673
00:46:21.079 --> 00:46:26.020
If you lose your hydraulic system you had
a bad day.

674
00:46:26.020 --> 00:46:27.839
And there are three systems.

675
00:46:27.839 --> 00:46:32.972
I do believe there is one place where there's
a single point failure in the hydraulic system.

676
00:46:32.720 --> 00:46:35.720
It's pretty hard to eliminate all single point
phase.

677
00:46:35.240 --> 00:46:36.230
I believe that.

678
00:46:36.230 --> 00:46:41.163
When Henry Pohl talks, he's going to be doing
a very detailed discussion on the hydraulic

679
00:46:40.559 --> 00:46:42.292
system, you might ask him that.

680
00:46:41.869 --> 00:46:47.420
I don't recall, but he'll tell you whether
there is a single point failure in the hydraulic

681
00:46:47.420 --> 00:46:48.390
system.

682
00:46:48.390 --> 00:46:53.049
And this is a schematic of the hydraulic system.

683
00:46:53.049 --> 00:46:57.690
I am not going to go through the details of
it because I'm not sure I could explain it.

684
00:46:57.690 --> 00:47:02.356
But basically this is the hydraulic system
that shows how system one, system two and

685
00:47:02.270 --> 00:47:07.970
system three is tied into the right outboard
elevon, the right inboard elevon and so forth

686
00:47:07.970 --> 00:47:09.059
and so on.

687
00:47:09.059 --> 00:47:12.200
The main engines.

688
00:47:12.200 --> 00:47:14.589
The external tank.

689
00:47:14.589 --> 00:47:20.670
And we've never had a loss in the hydraulic
system.

690
00:47:20.670 --> 00:47:25.670
We did test the hydraulic system in what we
call the flight control hydraulics laboratory

691
00:47:25.349 --> 00:47:32.349
at Downey where we had actually all the hydraulic
systems tied together with the computer system.

692
00:47:32.480 --> 00:47:37.510
And actually flew the vehicle, what we called
this iron bird, with a hydraulic system.

693
00:47:37.510 --> 00:47:39.710
And we did have a failure there one time.

694
00:47:39.510 --> 00:47:44.309
Early in the program, we had a single point
failure and lost all the hydraulic fluid.

695
00:47:44.309 --> 00:47:49.175
We had to go back and make a major change
to the actuator system, to the hydraulic system.

696
00:47:48.380 --> 00:47:48.913
Yes, sir.

697
00:47:48.559 --> 00:47:53.692
I'm just wondering how the hydraulic system
on the shuttle compares to the hydraulic system

698
00:47:53.210 --> 00:47:54.970
on an aircraft?

699
00:47:54.970 --> 00:47:56.670
An airplane.

700
00:47:56.670 --> 00:47:57.519
Yeah.

701
00:47:57.519 --> 00:48:02.210
I'm really not sure I can explain it.

702
00:48:02.210 --> 00:48:04.276
I think there's not much difference.

703
00:48:03.880 --> 00:48:08.519
Let me tell you the only difference.

704
00:48:08.519 --> 00:48:13.940
I think airplanes have three hydraulic systems.

705
00:48:13.940 --> 00:48:16.940
The shuttle started out with four hydraulic
systems.

706
00:48:16.369 --> 00:48:20.969
We actually started out with four, but it
was so heavy and so complicated we decided

707
00:48:20.519 --> 00:48:21.819
to go to three.

708
00:48:21.819 --> 00:48:26.930
And I think the airplanes have three hydraulic
systems, if I'm not mistaken.

709
00:48:26.930 --> 00:48:27.996
Does anybody know?

710
00:48:27.510 --> 00:48:30.510
I at least know quite a few that have three.

711
00:48:30.510 --> 00:48:32.776
I don't know if all airplanes have three.

712
00:48:32.369 --> 00:48:39.200
The big difference in it is that the hydraulic
system in the shuttle is powered by what we

713
00:48:39.200 --> 00:48:41.829
call an auxiliary power unit.

714
00:48:41.829 --> 00:48:44.430
And that's what pressurizes the system.

715
00:48:44.430 --> 00:48:50.619
And I think on an airplane it's powered by
the engine itself.

716
00:48:50.619 --> 00:48:55.460
But this system is pressurized by what we
call an auxiliary power unit.

717
00:48:55.460 --> 00:48:59.420
An auxiliary power unit is a box about this
big.

718
00:48:59.420 --> 00:49:01.920
It generates 135 horsepower.

719
00:49:01.920 --> 00:49:08.410
And it's got a ten inch turbine wheel that
goes about 10,000 to 20,000 RPM.

720
00:49:08.410 --> 00:49:11.010
And actually it's fueled by hydrazine.

721
00:49:11.010 --> 00:49:18.010
And it essentially pressurizes the system
to get you up to 3000 PSI.

722
00:49:19.720 --> 00:49:26.720
Again, if this auxiliary power unit doesn't
work, we have three of them, it's a bad day.

723
00:49:27.309 --> 00:49:31.975
And I think we did have some problems with
one of the auxiliary power units at one time

724
00:49:30.349 --> 00:49:32.140
during ascent.

725
00:49:32.140 --> 00:49:37.339
But that's the major difference, I think,
because I think we tried to copy pretty much

726
00:49:37.339 --> 00:49:41.672
aircraft designs using the same type of hydraulic
fluid and everything else.

727
00:49:40.990 --> 00:49:46.410
So I think we copied their standard in using
this, as I recall, except we're pressurized

728
00:49:46.410 --> 00:49:48.470
by the auxiliary power unit.

729
00:49:48.470 --> 00:49:53.779
Again, not to belabor the point, you're going
to have a very detailed briefing or lecture

730
00:49:53.779 --> 00:49:58.645
on the hydraulic system, the auxiliary power
unit and the reaction control system, the

731
00:49:57.990 --> 00:49:59.390
OMS system by Henry Pohl.

732
00:49:59.200 --> 00:50:01.460
So, you will have more details on this.

733
00:50:01.460 --> 00:50:05.993
Again, the hydraulic system might be another
interesting thing to take a look at.

734
00:50:05.779 --> 00:50:10.179
I hope what I'm trying to get across to you
is how these systems all fit together.

735
00:50:09.200 --> 00:50:13.800
You cannot do the guidance, navigation and
control without the hydraulic system.

736
00:50:13.410 --> 00:50:17.180
You have the aerodynamics and you have the
aerothermodynamics.

737
00:50:17.180 --> 00:50:20.913
You've got the structures and everything that
has to fit together.

738
00:50:20.250 --> 00:50:25.050
And you can imagine the systems engineering
problem associated with trying to put all

739
00:50:23.829 --> 00:50:24.900
that together.

740
00:50:24.900 --> 00:50:31.900
Just to remind you of a few other things that
you have to deal with.

741
00:50:32.529 --> 00:50:38.779
When you're working with a space system that
also makes it a little bit different from

742
00:50:38.779 --> 00:50:40.245
designing for the ground.

743
00:50:39.579 --> 00:50:46.579
For instance, you have a fuel tank with the
hydrazine inert.

744
00:50:48.609 --> 00:50:53.359
This is a generic problem with any liquid
tank.

745
00:50:53.359 --> 00:50:59.890
Once you're in weightlessness, how do you
get the liquid to flow out?

746
00:50:59.890 --> 00:51:06.890
This is actually a fairly traditional old-fashioned
design where they have a diaphragm in the

747
00:51:07.769 --> 00:51:08.279
tank.

748
00:51:08.279 --> 00:51:13.069
And, on one side of the diaphragm, you pressurize
it with either helium or nitrogen.

749
00:51:13.069 --> 00:51:16.650
And that pushes the material.

750
00:51:16.650 --> 00:51:20.180
It's basically sort of like squeezing it out
of a bag.

751
00:51:20.180 --> 00:51:24.359
The problem is that hydrazine is nasty stuff.

752
00:51:24.359 --> 00:51:31.359
And in the orbiter maneuvering and reaction
control systems they decided that, for reusability,

753
00:51:31.660 --> 00:51:34.000
they didn't want to use diaphragms.

754
00:51:34.000 --> 00:51:37.349
And so we'll probably learn more about some
of the details.

755
00:51:37.349 --> 00:51:43.130
But there's a very elaborate screen mechanism
which uses surface tension to collect the

756
00:51:43.130 --> 00:51:43.859
material.

757
00:51:43.859 --> 00:51:49.390
And just getting liquids out of a tank into
where you want to go is something you have

758
00:51:49.390 --> 00:51:50.723
to worry about in space.

759
00:51:50.420 --> 00:51:55.430
The second problem is a thermal problem.

760
00:51:55.430 --> 00:51:59.430
You're not flying through the atmosphere so
you don't have air cooling.

761
00:51:58.579 --> 00:52:01.049
As you see, you've got the gear box.

762
00:52:01.049 --> 00:52:02.849
You're generating a lot of heat.

763
00:52:02.779 --> 00:52:07.390
And, actually, in order to cool, they use
water spray boilers.

764
00:52:07.390 --> 00:52:13.579
And you essentially, we actually do this to
get rid of heat from the orbiter as well before

765
00:52:13.579 --> 00:52:17.260
we open the payload bay doors which have radiators.

766
00:52:17.260 --> 00:52:21.690
While those are closed, it has to be done
with a water spray boiler.

767
00:52:21.690 --> 00:52:26.579
And so you get rid of all your heat by putting
it into a heat exchanger.

768
00:52:26.579 --> 00:52:28.712
And you basically shoot liquid water.

769
00:52:28.430 --> 00:52:34.559
And, of course, in a vacuum the water flash
evaporates and that takes the heat away.

770
00:52:34.559 --> 00:52:40.599
And so, although in essence the control system
is similar to airplanes, even there, there

771
00:52:40.599 --> 00:52:47.599
are a lot of special design features that
have to be put in because this is a system

772
00:52:47.799 --> 00:52:49.599
that has to work in space as well.

773
00:52:49.359 --> 00:52:50.759
That's a very good point.

774
00:52:50.670 --> 00:52:53.270
The cooling is one of the biggest differences.

775
00:52:52.950 --> 00:52:59.950
And because this system is so complex and
heavy and needs a lot of maintenance and uses

776
00:53:01.279 --> 00:53:08.279
hydrazine, which is very nasty stuff, there
have been, on various occasions, studies of

777
00:53:09.329 --> 00:53:12.900
could this system be replaced by an electromechanical
system?

778
00:53:12.900 --> 00:53:19.900
And as motors become more powerful and battery
and fuel cell systems are more efficient,

779
00:53:21.430 --> 00:53:27.150
I think just about two years ago we gave up
on the last effort, but it always turned out

780
00:53:27.150 --> 00:53:29.980
to be too heavy.

781
00:53:29.980 --> 00:53:36.059
To get an electromechanical system which had
enough muscle to move these air surfaces around,

782
00:53:36.059 --> 00:53:38.349
it is just beyond what we can do.

783
00:53:38.349 --> 00:53:41.682
But that might be another good system to take
a look at today.

784
00:53:40.329 --> 00:53:42.129
It might be another good system.

785
00:53:41.789 --> 00:53:43.789
The other thing.

786
00:53:43.789 --> 00:53:47.750
You see where it has a speed control and safety
for the APU controller?

787
00:53:47.750 --> 00:53:54.240
The interesting thing about this turbine wheel,
I forget the exact RPM, but it's pretty high.

788
00:53:54.240 --> 00:53:56.920
I think it's at least 10,000 to 20,000 RPM.

789
00:53:56.920 --> 00:54:03.920
If this shaft should break off, it's a very
hard to control it in the box.

790
00:54:04.500 --> 00:54:09.680
I mean it will go right through the box it's
in and share the vehicle.

791
00:54:09.680 --> 00:54:11.769
We've tried everything we know.

792
00:54:11.769 --> 00:54:13.569
We've put protection around it.

793
00:54:13.529 --> 00:54:18.529
We've put a lot of margin into the turbine
wheel, into the shaft, but that's a very critical

794
00:54:17.910 --> 00:54:18.339
thing.

795
00:54:18.339 --> 00:54:23.605
And, as Professor Hoffman mentioned, there
have been many exercises to replace the auxiliary

796
00:54:23.349 --> 00:54:24.015
power unit.

797
00:54:23.720 --> 00:54:28.453
And I think again this would be another good
challenge to take a look at seeing what you

798
00:54:27.859 --> 00:54:31.859
could do to come up with a different design
for the auxiliary power unit.

799
00:54:31.599 --> 00:54:34.999
But there will be other systems that you might
want to look at.

800
00:54:33.510 --> 00:54:39.110
But I thought I'd just give you a little discussion
of some that I personally think are very pertinent

801
00:54:38.900 --> 00:54:39.980
to look at.

802
00:54:39.980 --> 00:54:45.313
That's the thermal protection system, the
structures, the guidance, navigation and control,

803
00:54:44.619 --> 00:54:46.952
the hydraulic system, including the APU.

804
00:54:46.859 --> 00:54:49.459
And these, I think, would be a very good system.

805
00:54:48.220 --> 00:54:52.153
Now, you might pick others, but these might
be very good ones to look at.

806
00:54:51.579 --> 00:54:58.579
Let me wind up my discussion by talking to
you about what I think you ought to look for

807
00:54:59.509 --> 00:55:00.309
in the system.

808
00:55:00.150 --> 00:55:05.579
This is just a very simplistic chart, but
this is my way of thinking about what you

809
00:55:05.579 --> 00:55:09.519
do when you go about designing something.

810
00:55:09.519 --> 00:55:11.385
You need to look at the functions.

811
00:55:10.769 --> 00:55:15.569
As we pointed out yesterday, the functions
are very important because, when we talked

812
00:55:15.359 --> 00:55:20.630
about a thermal protection system , we looked
at the functions of protecting the vehicle,

813
00:55:20.630 --> 00:55:24.630
maintaining that back surface temperature
to 350 degrees Fahrenheit.

814
00:55:24.539 --> 00:55:28.259
We worked that to finite detail.

815
00:55:28.259 --> 00:55:32.925
We knew exactly how thick the tiles had to
be, what the characteristics had to be, but

816
00:55:32.559 --> 00:55:33.225
what did we?

817
00:55:32.680 --> 00:55:39.349
We forgot, oddly enough, that it had to be
attached to the vehicle, which is sort of

818
00:55:39.349 --> 00:55:40.250
dumb.

819
00:55:40.250 --> 00:55:43.583
And you would think, my gosh, they ought to
be able to do that.

820
00:55:42.960 --> 00:55:46.493
But you're infinitely smarter after you find
out your problem.

821
00:55:46.150 --> 00:55:50.750
One thing you ought to do is really understand
what functions have to be performed.

822
00:55:50.750 --> 00:55:54.279
And you might say that becomes your functional
requirements.

823
00:55:54.279 --> 00:55:57.279
The whole thing is understanding your requirements.

824
00:55:57.190 --> 00:56:01.069
Then you ought to understand what performance
is required.

825
00:56:01.069 --> 00:56:03.535
In other words, performance requirements.

826
00:56:02.210 --> 00:56:07.676
You ought to have a first order of magnitude
calculation of what kind of performance requirements

827
00:56:07.430 --> 00:56:08.089
you need.

828
00:56:08.089 --> 00:56:13.450
A lot of times this is going to have come
from assumptions, talking to people, getting

829
00:56:13.450 --> 00:56:14.869
experts involved.

830
00:56:14.869 --> 00:56:17.335
But what kind of performance requirements?

831
00:56:17.279 --> 00:56:22.012
It is going to have to be iterated, but what
kind of performance are you thinking about

832
00:56:20.519 --> 00:56:21.779
in this system?

833
00:56:21.779 --> 00:56:26.579
Whatever the system may be, hydraulic system,
thermal protection system, whatever.

834
00:56:26.180 --> 00:56:32.130
Then we talk about the three-legged stool,
as Professor Hoffman said.

835
00:56:32.130 --> 00:56:36.750
We talk about schedule, cost and output weight
under performance.

836
00:56:36.750 --> 00:56:42.000
Because, as I told you before, the first thing
you're going to wind up, in designing a system,

837
00:56:42.000 --> 00:56:44.333
is that the weight is going to get too high.

838
00:56:44.170 --> 00:56:47.559
Then you're going to find out that performance
goes down.

839
00:56:47.559 --> 00:56:48.959
You have schedule slips.

840
00:56:48.450 --> 00:56:53.183
But the first thing that usually happens is
you wake up in the morning and you find out,

841
00:56:52.410 --> 00:56:57.410
my gosh, my system weighs a lot more, my subsystem
weighs a lot more than they told me I could

842
00:56:56.410 --> 00:56:56.750
have.

843
00:56:56.750 --> 00:56:59.869
So, you've got to understand your weight.

844
00:56:59.869 --> 00:57:03.535
And then you need to think about what is the
available technology?

845
00:57:03.410 --> 00:57:05.343
What is the technology available?

846
00:57:05.180 --> 00:57:11.339
As somebody pointed out, today the avionics
technology is probably pretty high up on the

847
00:57:11.339 --> 00:57:12.130
ladder.

848
00:57:12.130 --> 00:57:15.730
And you could probably pick something today
right off the shelf.

849
00:57:14.289 --> 00:57:18.955
Although, in my experience of the 30 years
I had in the space program, I never was able

850
00:57:18.670 --> 00:57:21.250
to find something that was off the shelf.

851
00:57:21.250 --> 00:57:25.516
Space programs just don't usually allow you
to take something off the shelf.

852
00:57:24.720 --> 00:57:27.190
People told me to go do it.

853
00:57:27.190 --> 00:57:29.990
And, once I went and did it, we changed everything.

854
00:57:29.920 --> 00:57:34.453
But today, in the technology we have in the
avionics, you may be able to get a lot off

855
00:57:34.380 --> 00:57:35.059
the shelf.

856
00:57:35.059 --> 00:57:37.720
So, what technology is available?

857
00:57:37.720 --> 00:57:42.253
And then one of the key things, one of the
biggest things you have to know is what are

858
00:57:41.500 --> 00:57:42.433
the interfaces?

859
00:57:42.049 --> 00:57:48.420
If you could see the multitude of interfaces
that are required for the guidance, navigation

860
00:57:48.420 --> 00:57:53.486
and control system, it takes into consideration
all the interfaces you could think about.

861
00:57:52.890 --> 00:57:57.690
And so you need to think about interfaces,
whether they be mechanical, whether they be

862
00:57:56.920 --> 00:57:59.253
electrical, whether they be functional.

863
00:57:58.980 --> 00:58:02.646
So, you need to think about what interfaces
you're talking about.

864
00:58:02.210 --> 00:58:05.610
And, to me, those are some guidelines you
need to think about.

865
00:58:05.579 --> 00:58:11.329
Of course then we talk about cost and schedule.

866
00:58:11.329 --> 00:58:17.509
Usually your cost is going to grow, unfortunately,
and usually your schedule is going to slip.

867
00:58:17.509 --> 00:58:21.430
And those are, what I would call, career limiting
problems.

868
00:58:21.430 --> 00:58:27.009
That's the best way to get fired, to have
your costs go up and you schedule increase.

869
00:58:27.009 --> 00:58:34.009
So, these are some of my guidelines for things
you ought to look for when you try to design

870
00:58:34.150 --> 00:58:35.109
your system.

871
00:58:35.109 --> 00:58:40.789
I would be happy to answer any questions for
you that you may have.

872
00:58:40.789 --> 00:58:43.130
Yes, sir.

873
00:58:43.130 --> 00:58:48.480
About taking technology off the shelf, I'm
wondering, and I don't think, from what I

874
00:58:48.480 --> 00:58:53.146
know, it was really thought of much during
the shuttle, but the idea of maybe putting

875
00:58:52.200 --> 00:58:57.466
something on the shelf, so to speak, the idea
of designing something, a subsystem or something

876
00:58:57.210 --> 00:59:04.210
so it would have the flexibility to be used
in future systems.

877
00:59:08.549 --> 00:59:10.015
Do you see where I'm going?

878
00:59:09.470 --> 00:59:13.640
No, I don't think I quite follow what you're
saying.

879
00:59:13.640 --> 00:59:14.750
Try again.

880
00:59:14.750 --> 00:59:19.483
Well, you said there wasn't really off the
shelf technology available then but maybe

881
00:59:17.160 --> 00:59:17.893
there is now.

882
00:59:17.619 --> 00:59:22.352
The idea I'm thinking about is the idea of
designing something not so much just for the

883
00:59:21.390 --> 00:59:26.640
shuttle in this phase, but so that it could
be used for other things.

884
00:59:26.640 --> 00:59:31.000
Well, that's a very possible thing to do and
would be a very good thing to do.

885
00:59:31.000 --> 00:59:35.866
In my experience, and we tried something like
that, usually this tends to start growing

886
00:59:35.220 --> 00:59:36.309
into it.

887
00:59:36.309 --> 00:59:40.109
You start saying, well, what is it really
going to cost you to do that?

888
00:59:39.349 --> 00:59:44.015
I know, when I was project manager, people
would come to me with something like that.

889
00:59:43.759 --> 00:59:46.440
And I used to be a pretty mean guy.

890
00:59:46.440 --> 00:59:49.230
I'm not quite as mean as I used to be.

891
00:59:49.230 --> 00:59:54.230
But that's the first thing I'd ask them, what
about the cost, because that's what happens.

892
00:59:54.029 --> 00:59:58.895
When you start trying to make multiple uses
out of something, you usually drive the cost

893
00:59:57.890 --> 00:59:58.140
up.

894
00:59:57.890 --> 01:00:04.890
And that's what you 
have 

895
01:00:56.230 --> 01:01:01.009
to be careful of.

896
01:01:01.009 --> 01:01:04.150
Yes, sir.

897
01:01:04.150 --> 01:01:11.150
[UNINTELLIGIBLE PHRASE] Well, let me add to
that.

898
01:01:17.829 --> 01:01:24.829
I feel very strongly that had it not been
for the MIT Instrumentation Lab or the Draper

899
01:01:26.089 --> 01:01:31.155
Lab or the people they had there, the technology
they had there, we wouldn't have gone to the

900
01:01:29.269 --> 01:01:31.602
moon when we said we were going to doing it.

901
01:01:31.190 --> 01:01:36.779
I mean I worked very closely with them, and
I feel very strongly that Draper Labs, I keep

902
01:01:36.779 --> 01:01:41.445
getting them mixed up, at that time the MIT
Instrumentation Lab was really one of the

903
01:01:40.920 --> 01:01:42.786
prime movers of the whole system.

904
01:01:42.410 --> 01:01:46.119
It was really fantastic.

905
01:01:46.119 --> 01:01:50.919
So the people working here, and you can take
advantage of that, would be very useful for

906
01:01:50.839 --> 01:01:53.000
you to do that.

907
01:01:53.000 --> 01:01:54.609
Any other questions?

908
01:01:54.609 --> 01:01:58.640
Well, I will be back on the 22nd.

909
01:01:58.640 --> 01:02:02.109
And I look forward to working with you some
more.

910
01:02:02.109 --> 01:02:03.175
One more question.

911
01:02:02.849 --> 01:02:03.519
Sorry.

912
01:02:03.519 --> 01:02:04.190
Yes.

913
01:02:04.190 --> 01:02:11.190
It has not as much to do with the subsystems
but to the overall concept of the shuttle.

914
01:02:16.880 --> 01:02:23.880
I was wondering why, if you know at all, the
military thought it was important to have

915
01:02:29.519 --> 01:02:32.452
the ability to capture a satellite and bring
it back?

916
01:02:29.849 --> 01:02:34.582
Was it because satellites were so expensive
at the time and maybe they aren't as much?

917
01:02:30.589 --> 01:02:33.122
Because I don't think we've really done that.

918
01:02:30.960 --> 01:02:33.026
Well, it really wasn't the military.

919
01:02:31.240 --> 01:02:33.373
Several satellites we did bring back.

920
01:02:32.839 --> 01:02:35.740
I cannot recall which ones.

921
01:02:35.740 --> 01:02:36.900
Westar and Palapa.

922
01:02:36.900 --> 01:02:39.033
I have pictures of that a little later.

923
01:02:38.779 --> 01:02:40.700
And we retrieved those.

924
01:02:40.700 --> 01:02:47.700
And it turns out, interestingly enough, they
were insured by Lloyds of London.

925
01:02:48.490 --> 01:02:55.390
And that was the biggest salvage operation
Lloyds of London ever achieved when they returned

926
01:02:55.390 --> 01:02:59.456
those satellites, bigger than anything in
the ocean they ever picked up.

927
01:02:57.990 --> 01:02:59.549
In fact, they rang the bell.

928
01:02:59.549 --> 01:03:03.815
When they have a big recovery, a big thing
in Lloyds of London they ring a bell.

929
01:03:03.809 --> 01:03:08.475
And they came down to serve somebody, whoever
he was, I don't recall who he was, but he

930
01:03:07.970 --> 01:03:10.109
was head of Lloyds of London.

931
01:03:10.109 --> 01:03:15.339
And we had a big reception at the Johnson
Space Center after we retrieved Westar and

932
01:03:15.339 --> 01:03:16.089
Palapa.

933
01:03:16.089 --> 01:03:20.920
I don't think the Air Force really had that
much demand at the time, or it went away,

934
01:03:20.920 --> 01:03:27.099
whatever it was, for retrieving payloads,
but commercials did.

935
01:03:27.099 --> 01:03:32.559
What the military was interested in was the
possibility of refueling satellites in orbit.

936
01:03:32.559 --> 01:03:33.359
That's right.

937
01:03:33.170 --> 01:03:33.970
We did do that.

938
01:03:33.660 --> 01:03:39.609
Because when you have recognizant satellites,
very often you have to change their orbit

939
01:03:39.609 --> 01:03:42.475
to get them over to the right place at the
right time.

940
01:03:42.460 --> 01:03:49.140
And orbital maneuvering fuel is a limiting
commodity on satellites.

941
01:03:49.140 --> 01:03:51.940
And these are very expensive satellites to
build.

942
01:03:51.539 --> 01:03:58.539
So if you have the possibility of refueling
then, in principle, you could extend the life

943
01:03:59.249 --> 01:04:01.549
of these very high value assets.

944
01:04:01.549 --> 01:04:05.880
And we did do a demonstration.

945
01:04:05.880 --> 01:04:10.910
Of course, the fuel, in most cases, is hydrazine
which is very nasty stuff.

946
01:04:10.910 --> 01:04:16.720
If you get it on your spacesuit you cannot
come inside until you bake it off.

947
01:04:16.720 --> 01:04:20.140
It's fairly dangerous.

948
01:04:20.140 --> 01:04:27.140
And so we actually did do a demonstration
just in the shuttle's cargo bay, but we've

949
01:04:28.569 --> 01:04:35.569
never actually done a real refueling of a
satellite in orbit.

950
01:04:36.170 --> 01:04:37.970
But they're still working on it.

951
01:04:37.329 --> 01:04:44.329
Now I think the military is still working
on possibly robotic refuelling technologies.

952
01:04:45.630 --> 01:04:52.630
For whatever the next version of the shuttle
or crew vehicle would be, is it necessary

953
01:04:56.380 --> 01:04:58.913
or even a good idea to have this huge cargo
bay?

954
01:04:57.990 --> 01:05:00.656
Well, I think that's what they're eliminating.

955
01:04:59.380 --> 01:05:01.113
I haven't been that close to it.

956
01:05:00.740 --> 01:05:04.890
But the CEV is going to be really a passenger
carrier.

957
01:05:04.890 --> 01:05:08.700
And then any cargo will be on an unmanned
vehicle, I believe.

958
01:05:08.700 --> 01:05:10.766
So, that's what they're separating.

959
01:05:10.279 --> 01:05:11.089
Is that right?

960
01:05:11.089 --> 01:05:14.809
I mean I haven't really been that close to
it.

961
01:05:14.809 --> 01:05:21.069
This is one of the guidelines now for future
space vehicles, is to the maximum extent possible

962
01:05:21.069 --> 01:05:25.130
separate humans and cargo.

963
01:05:25.130 --> 01:05:32.130
If the original concept of the shuttle had
been realizable that the shuttle would be

964
01:05:33.230 --> 01:05:39.799
capable of flying frequently enough that it
could basically satisfy all of our launch

965
01:05:39.799 --> 01:05:45.869
needs then you can make the argument, well,
all right, we're doing this and people are

966
01:05:45.869 --> 01:05:49.470
in it to fly it and we'll just do it that
way.

967
01:05:49.470 --> 01:05:56.470
But given the fact that we cannot fulfill
that goal then you have to ask why put humans

968
01:05:57.779 --> 01:06:04.779
at risk just to take a satellite up in the
cargo bay and launch it when we can launch

969
01:06:05.019 --> 01:06:07.152
satellites using unmanned vehicles?

970
01:06:06.950 --> 01:06:13.950
And, in fact, that was the decision after
the Challenger accident, was any payloads

971
01:06:15.999 --> 01:06:22.329
that are carried into space on the shuttle
in general, I mean there were some exceptions

972
01:06:22.329 --> 01:06:28.480
for various reasons, but you ought to be using
the shuttle to do things where you need people

973
01:06:28.480 --> 01:06:29.809
to do them.

974
01:06:29.809 --> 01:06:35.029
And some of those things, for instance, to
service in the Hubble or the assembly of the

975
01:06:35.029 --> 01:06:41.039
space station, although even that could be
argued that, had we planned it differently,

976
01:06:41.039 --> 01:06:45.505
we might have been able to do it without making
such extensive use of the shuttle.

977
01:06:45.200 --> 01:06:48.319
But there we do make full use of the big cargo
bay.

978
01:06:48.319 --> 01:06:54.660
But future human space vehicles, the CEV will
be basically a people carrier with a small

979
01:06:54.660 --> 01:06:56.150
amount of cargo.

980
01:06:56.150 --> 01:07:02.440
And any time you want to launch large amounts
of cargo you will do it without people.

981
01:07:02.440 --> 01:07:05.279
Let's take a one or two-minute break.

982
01:07:05.279 --> 01:07:08.130
I'm going to get my computer set up.

983
01:07:08.130 --> 01:07:15.130
Let me put this down here.

984
01:07:17.609 --> 01:07:24.609
I want to give you a short presentation just
to bring everybody up to a certain level of

985
01:07:28.690 --> 01:07:34.119
familiarity with what the shuttle does and
what it looks like.

986
01:07:34.119 --> 01:07:41.119
And, again, I tend to look at this from an
operational point of view.

987
01:07:41.499 --> 01:07:45.480
This will be informal, you know, ask questions
as we go through.

988
01:07:45.480 --> 01:07:52.480
As we've said, the two critical phases of
shuttle operations and what makes this such

989
01:07:54.410 --> 01:08:01.200
a unique vehicle is it launches vertically
like a spaceship with a tremendous amount

990
01:08:01.200 --> 01:08:04.999
of power.

991
01:08:04.999 --> 01:08:07.440
And it lands.

992
01:08:07.440 --> 01:08:14.240
You look at this, and you have to remind yourself
that it looks like an airplane landing and,

993
01:08:14.240 --> 01:08:18.779
yet, a half an hour ago this was a spaceship
going in orbit around the earth.

994
01:08:18.779 --> 01:08:25.779
So it really has been a spectacular technological
achievement.

995
01:08:28.389 --> 01:08:33.819
Let's go through some of the maintenance operations,
what is actually done to the shuttle.

996
01:08:33.819 --> 01:08:39.719
We've talked about it a little bit, but I
think if you actually see some of the images

997
01:08:39.719 --> 01:08:42.909
it will help to give some reality to some
of this.

998
01:08:42.909 --> 01:08:48.869
After the shuttle lands, here it's landing
on the runway at the Kennedy Space Center.

999
01:08:48.869 --> 01:08:53.602
And, as we mentioned, all of this is a bird
sanctuary so sometimes you have to chase the

1000
01:08:53.480 --> 01:08:54.420
birds away.

1001
01:08:54.420 --> 01:09:00.750
And there's a problem from time to time with
crosswinds.

1002
01:09:00.750 --> 01:09:06.259
There is only one runway so, if you get wind
blowing across the runway at more than 15

1003
01:09:06.259 --> 01:09:08.509
knots, you cannot land.

1004
01:09:08.509 --> 01:09:15.359
And so that's also a constraint sometimes
to launch because when you take off you always

1005
01:09:15.359 --> 01:09:20.639
have to be able to turn around and come back
and land here, just like you have to be able

1006
01:09:20.639 --> 01:09:24.589
to land over in Europe or Africa.

1007
01:09:24.589 --> 01:09:29.069
And so there are a lot of launch constraints.

1008
01:09:29.069 --> 01:09:36.069
What they do is, this was actually hooked
up back on the runway, but they hook up air

1009
01:09:39.190 --> 01:09:41.279
conditioning units.

1010
01:09:41.279 --> 01:09:43.770
They have to purge.

1011
01:09:43.770 --> 01:09:45.489
There's an ammonia boiler.

1012
01:09:45.489 --> 01:09:50.869
Remember we talked about getting rid of heat
as you're coming in using water spray boilers.

1013
01:09:50.869 --> 01:09:56.710
But, once you get below 100,000 feet, the
pressure is actually above the triple point

1014
01:09:56.710 --> 01:09:59.570
of water and you cannot flash evaporate anymore.

1015
01:09:59.570 --> 01:10:03.350
And so they switch from a water boiler to
an ammonia boiler.

1016
01:10:03.350 --> 01:10:07.550
And so, after the shuttle lands, there are
ammonia fumes all over the place.

1017
01:10:07.389 --> 01:10:12.922
If you've looked at pictures of shuttle servicing
on the runway, sometimes if there isn't actually

1018
01:10:12.400 --> 01:10:18.949
wind blowing they bring around a big fan to
blow the ammonia way.

1019
01:10:18.949 --> 01:10:21.619
And everybody has to stay upwind of the ammonia.

1020
01:10:21.619 --> 01:10:26.485
And there is also the possibility, of course,
that there might be a hydrazine leak or who

1021
01:10:25.989 --> 01:10:26.760
knows.

1022
01:10:26.760 --> 01:10:28.840
Anyway, the orbiter has to be safe.

1023
01:10:28.840 --> 01:10:34.110
And you have the people come out in what looks
like space suits.

1024
01:10:34.110 --> 01:10:36.810
Escape suits they call them.

1025
01:10:36.810 --> 01:10:40.760
Self-contained, I don't remember the acronym.

1026
01:10:40.760 --> 01:10:47.760
But, in any case, we're bringing the orbiter
back to the hanger area where it will undergo

1027
01:10:49.360 --> 01:10:51.790
a lot more than 14 days of servicing.

1028
01:10:51.790 --> 01:10:58.790
I remember, again, just to give you a sense
of the state of mind before we were actually

1029
01:11:00.800 --> 01:11:05.239
operating the shuttle, as a new astronaut
back in 1978.

1030
01:11:05.239 --> 01:11:07.639
Remember the shuttle didn't fly until '81.

1031
01:11:07.610 --> 01:11:11.143
We were getting a series of lectures on all
the shuttle systems.

1032
01:11:10.360 --> 01:11:15.440
And I remember the lecture they gave us on
turnaround, which was supposed to take 14

1033
01:11:15.440 --> 01:11:16.610
days.

1034
01:11:16.610 --> 01:11:20.543
And we got a briefing from the people who
were planning the turnaround.

1035
01:11:19.670 --> 01:11:26.670
And I remember they told us we've studied
this really carefully, and we just don't think

1036
01:11:26.850 --> 01:11:30.389
it's going to be possible to turn the shuttle
around in 14 days.

1037
01:11:30.389 --> 01:11:37.389
We've cut out every unnecessary step and we
think it's impossible to do it in less than

1038
01:11:38.150 --> 01:11:40.250
16 days.

1039
01:11:40.250 --> 01:11:43.583
[LAUGHTER] And that's kind of the way people
were thinking.

1040
01:11:43.250 --> 01:11:50.250
We were talking about it's supposed to make
60 flights a year, and people were skeptical.

1041
01:11:50.520 --> 01:11:55.380
There is no way they can make more than 40
flights a year.

1042
01:11:55.380 --> 01:12:02.380
People just didn't have a concept of how complex
it was going to be to operate this vehicle

1043
01:12:04.199 --> 01:12:07.790
because it is such a complex vehicle.

1044
01:12:07.790 --> 01:12:10.179
To operate it safety is difficult.

1045
01:12:10.179 --> 01:12:12.659
Now sometimes it lands in California.

1046
01:12:12.659 --> 01:12:17.690
And, in that case, you put it on the 747.

1047
01:12:17.690 --> 01:12:24.690
This is the same bipod fitting, just to essentially
duplicate the way that the orbiter is put

1048
01:12:26.100 --> 01:12:33.100
on the external tank, and the tail pod is,
of course, for aerodynamics.

1049
01:12:36.130 --> 01:12:41.219
And that was also the configuration for the
approach and landing tests.

1050
01:12:41.219 --> 01:12:46.889
And, actually, later, I think, in the middle
of October, Gordon Fullerton who was one of

1051
01:12:46.889 --> 01:12:53.889
NASA's premier test pilots, he still flies,
I mean I'll have to find out from him how

1052
01:12:53.929 --> 01:12:58.929
many different types of airplanes he's flow,
he's just an amazing guy, but he was actually

1053
01:12:58.550 --> 01:13:03.690
in the shuttle during that first approach
and landing test.

1054
01:13:03.690 --> 01:13:08.710
So he can tell us about what it was actually
like test flying the shuttle, as well as being

1055
01:13:08.710 --> 01:13:11.540
on the third orbital flight test.

1056
01:13:11.540 --> 01:13:11.989
Yes?

1057
01:13:11.989 --> 01:13:15.139
Were they carrying anything on the airplane?

1058
01:13:15.139 --> 01:13:16.940
You mean inside here?

1059
01:13:16.940 --> 01:13:17.380
Yeah.

1060
01:13:17.380 --> 01:13:22.630
No, this is not your opportunity for a transcontinental
vacation trip.

1061
01:13:22.630 --> 01:13:27.896
[LAUGHTER] I mean there are a few people who
ride along with it because you need the maintenance

1062
01:13:27.750 --> 01:13:28.216
people.

1063
01:13:28.050 --> 01:13:35.050
They also have an airplane flying about 50
miles in front of this checking for turbulence.

1064
01:13:35.920 --> 01:13:39.830
And, in the early days, they had a chase airplane
as well.

1065
01:13:39.830 --> 01:13:46.830
I told people they were crazy trying to get
them to do this because I thought it was the

1066
01:13:49.389 --> 01:13:50.789
dumbest thing I heard of.

1067
01:13:49.480 --> 01:13:50.346
[LAUGHTER] OK.

1068
01:13:49.520 --> 01:13:51.320
Now a look at some of the details.

1069
01:13:51.100 --> 01:13:57.159
Remember we talked about how the engines are
taken out?

1070
01:13:57.159 --> 01:14:00.759
You get a little bit of a view here inside
the engine compartment.

1071
01:14:00.489 --> 01:14:05.489
I had the chance, on numerous occasions, to
actually go inside the engine compartment.

1072
01:14:05.489 --> 01:14:06.889
I mean it's just amazing.

1073
01:14:06.650 --> 01:14:08.980
You get these huge big pipes.

1074
01:14:08.980 --> 01:14:13.580
And it really helps when you're going to be
using a system like this.

1075
01:14:13.580 --> 01:14:16.630
We spent a lot of time in the simulators.

1076
01:14:16.630 --> 01:14:23.630
And you'll flip a switch, and that switch
controls what they call the main fuel shutoff

1077
01:14:25.070 --> 01:14:26.960
valve.

1078
01:14:26.960 --> 01:14:31.920
It's a big butterfly valve about 17 inches
in diameter inside this huge pipe.

1079
01:14:31.920 --> 01:14:37.750
And you sit in the simulator and you flick
the switch and the talk back shows that the

1080
01:14:37.750 --> 01:14:38.683
thing is closed.

1081
01:14:38.580 --> 01:14:44.210
And then you actually go in the compartment
and you look and there's this huge pipe and

1082
01:14:44.210 --> 01:14:45.250
this area.

1083
01:14:45.250 --> 01:14:49.929
And you realize this huge thing that's moving
around.

1084
01:14:49.929 --> 01:14:52.062
And it kind of gives a sense of realism.

1085
01:14:51.830 --> 01:14:57.389
And, in fact, that's one of the big safety
concerns.

1086
01:14:57.389 --> 01:15:02.255
When the fuel is flowing, the butterfly valve
is in a vertical position so the fuel flips

1087
01:15:02.060 --> 01:15:02.760
by it.

1088
01:15:02.760 --> 01:15:05.026
Obviously, it's an unstable situation.

1089
01:15:04.780 --> 01:15:11.110
If it goes out just a little bit then the
fuel flow can slam it closed and you've got

1090
01:15:11.110 --> 01:15:12.643
an explosion on your hands.

1091
01:15:12.639 --> 01:15:16.030
So that was a major consideration.

1092
01:15:16.030 --> 01:15:17.800
This is the body flap.

1093
01:15:17.800 --> 01:15:21.650
So, you can see all of the plumbing.

1094
01:15:21.650 --> 01:15:28.650
And all these red things are removed before
flight, stickers.

1095
01:15:29.420 --> 01:15:31.590
It's a very, very complex process.

1096
01:15:31.590 --> 01:15:38.590
And they pull the engines out after every
flight now.

1097
01:15:39.150 --> 01:15:45.179
That's the thing, all of the platforms have
to be designed so that they fold up and they

1098
01:15:45.179 --> 01:15:48.112
fold down so that you can get access to all
the places.

1099
01:15:47.989 --> 01:15:51.210
I mean it's a very complex system.

1100
01:15:51.210 --> 01:15:56.989
And a lot of the equipment, the launch platforms
and everything, as we mentioned, were adapted

1101
01:15:56.989 --> 01:15:58.980
from the Apollo program.

1102
01:15:58.980 --> 01:16:04.880
But the hangers, which we call the OPF, the
orbiter processing facility was built specifically

1103
01:16:04.880 --> 01:16:05.813
for the shuttle.

1104
01:16:05.570 --> 01:16:09.610
The tiles we talked about.

1105
01:16:09.610 --> 01:16:16.610
I mean that's just a huge amount of work replacing,
maintaining and testing the tiles.

1106
01:16:19.210 --> 01:16:23.670
This is inside the cargo bay.

1107
01:16:23.670 --> 01:16:25.136
You've got the fuel cells.

1108
01:16:24.980 --> 01:16:30.020
You've got hydrogen and oxygen cryogenic tanks.

1109
01:16:30.020 --> 01:16:31.880
Helium pressurization tanks.

1110
01:16:31.880 --> 01:16:34.340
Nitrogen for your atmospheric system.

1111
01:16:34.340 --> 01:16:40.460
This is the bulkhead in front of which on
one side you have the engine compartment.

1112
01:16:40.460 --> 01:16:43.126
On the other side you have the crew compartment.

1113
01:16:43.010 --> 01:16:49.610
And, like we mentioned, this has to be done
essentially in clean-room conditions and yet

1114
01:16:49.610 --> 01:16:51.570
it's on the scale of a battleship.

1115
01:16:51.570 --> 01:16:56.330
So, it's a real challenge.

1116
01:16:56.330 --> 01:16:59.880
This is the forward window.

1117
01:16:59.880 --> 01:17:06.440
On maybe one in every five flights we'll get
a little ding on the windshield from a little

1118
01:17:06.440 --> 01:17:08.980
piece of usually orbital debris.

1119
01:17:08.980 --> 01:17:13.900
In fact, more often than not, it turns out
to be little paint chips.

1120
01:17:13.900 --> 01:17:19.889
Whenever they do that they remove the window,
they replace it and do a chemical analysis

1121
01:17:19.889 --> 01:17:26.230
to see whether it was a micrometeorite or
a piece of space debris.

1122
01:17:26.230 --> 01:17:29.889
The windows, actually there are three panes.

1123
01:17:29.889 --> 01:17:34.300
There's a redundant pressure pane.

1124
01:17:34.300 --> 01:17:40.610
The two panes on the inside are capable of
holding pressure and the outer is a thermal

1125
01:17:40.610 --> 01:17:45.650
pane.

1126
01:17:45.650 --> 01:17:49.610
This is one of the orbital maneuvering system
pods.

1127
01:17:49.610 --> 01:17:56.610
These are removable because, again, they contain
nitrogen tetroxide and hydrazine.

1128
01:17:57.530 --> 01:18:01.780
And we mentioned the fact that these are called
hypergolic fuels.

1129
01:18:01.780 --> 01:18:07.313
When you bring them together they ignite spontaneously,
as opposed to hydrogen and oxygen you need

1130
01:18:07.170 --> 01:18:09.510
a spark igniter.

1131
01:18:09.510 --> 01:18:15.480
So, in that one sense, it's a nice system
because when you want to use them in your

1132
01:18:15.480 --> 01:18:20.146
reaction control and you only want a very
tiny tenth of a second pulse, you don't have

1133
01:18:20.110 --> 01:18:23.510
to worry about an igniter which is a potential
failure point.

1134
01:18:23.489 --> 01:18:28.690
You just squirt in the hydrazine and the nitrogen
tetroxide.

1135
01:18:28.690 --> 01:18:30.356
But they're very nasty stuff.

1136
01:18:30.010 --> 01:18:37.010
They are extremely toxic and, of course, highly
combustible and they are very corrosive.

1137
01:18:37.980 --> 01:18:44.980
So, these pods are serviced in a place far
away from where the other activities take

1138
01:18:45.510 --> 01:18:50.110
place for the orbiter so just in case there
is a leak or an explosion it's not going to

1139
01:18:49.580 --> 01:18:52.900
take down the rest of the critical facilities.

1140
01:18:52.900 --> 01:18:58.560
This is the orbiter maneuvering engine, and
then they also have these smaller reaction

1141
01:18:58.560 --> 01:19:01.940
control engines.

1142
01:19:01.940 --> 01:19:04.900
And there are two aft pods.

1143
01:19:04.900 --> 01:19:11.040
And all the fuel tanks with the hydrazine
and nitrogen tetroxide are in here.

1144
01:19:11.040 --> 01:19:16.719
The aft system, the two pods, they actually
have inner connects so that you can actually

1145
01:19:16.719 --> 01:19:19.340
cross-feed from one system to the other.

1146
01:19:19.340 --> 01:19:21.570
And all of that stuff has to be hooked up.

1147
01:19:21.570 --> 01:19:24.500
The forward system is independent.

1148
01:19:24.500 --> 01:19:28.070
You cannot cross-feed to that.

1149
01:19:28.070 --> 01:19:29.420
The landing gears.

1150
01:19:29.420 --> 01:19:33.510
We talked a little bit the other day about
the tires.

1151
01:19:33.510 --> 01:19:37.469
These things sit up in space for two weeks
at a time.

1152
01:19:37.469 --> 01:19:39.869
You've got to worry about thermal control.

1153
01:19:39.560 --> 01:19:46.560
I mean can you imagine if you had a slow leak
and you found out that your tire was flat

1154
01:19:47.460 --> 01:19:51.699
before you started your reentry?

1155
01:19:51.699 --> 01:19:58.699
And then, of course, the problem of sealing
this against the hot gas.

1156
01:20:00.690 --> 01:20:07.690
The tiles on the edge of the doors for the
landing gear, that's a very critical section.

1157
01:20:09.040 --> 01:20:16.040
Anyway, after typically about a three month
turnaround in the hanger they wheel the orbiter,

1158
01:20:19.489 --> 01:20:26.489
actually, originally it was pulled over on
its own wheels, but that required that they

1159
01:20:26.670 --> 01:20:32.469
then stow the wheels in this big vertical
assembly building.

1160
01:20:32.469 --> 01:20:36.659
This is the vertical assembly building.

1161
01:20:36.659 --> 01:20:38.920
Hopefully you've seen pictures of it.

1162
01:20:38.920 --> 01:20:39.550
It's huge.

1163
01:20:39.550 --> 01:20:42.580
It was actually built to assemble the Saturn
rockets.

1164
01:20:42.580 --> 01:20:49.580
It's much taller than we need for the orbiter
stack, but it has been adapted.

1165
01:20:53.239 --> 01:21:00.239
So, what goes on here is it's wheeled into
the big vertical assembly building.

1166
01:21:05.270 --> 01:21:08.250
There it is actually on the inside.

1167
01:21:08.250 --> 01:21:12.770
You just don't get a sense of the size of
this building from any picture that can be

1168
01:21:12.770 --> 01:21:13.170
taken.

1169
01:21:12.900 --> 01:21:17.820
You have to be there and see it to really
appreciate it.

1170
01:21:17.820 --> 01:21:24.820
In the meantime, you remember the solid rocket
boosters are recovered after every flight.

1171
01:21:26.540 --> 01:21:32.080
And the Liberty Star and I think the Freedom
Star, that's the NASA Navy.

1172
01:21:32.080 --> 01:21:38.560
These boats are positioned out offshore.

1173
01:21:38.560 --> 01:21:45.130
And they actually have divers who go down
and put in plugs and floatation devices so

1174
01:21:45.130 --> 01:21:48.719
that they actually float the boosters.

1175
01:21:48.719 --> 01:21:54.750
And they drag them back where they're disassembled
and cleaned up.

1176
01:21:54.750 --> 01:22:01.750
The actual segments, which contain the fuel,
are shipped back to Utah to Thiokol which

1177
01:22:02.300 --> 01:22:07.080
is now ATK for cleaning, refilling.

1178
01:22:07.080 --> 01:22:14.080
And the other parts, the nozzle and the top,
which contains the electronics and the parachutes,

1179
01:22:14.320 --> 01:22:17.820
those are serviced in Florida.

1180
01:22:17.820 --> 01:22:24.820
And then they're brought in segments into
the vehicle assembly building where they are

1181
01:22:26.219 --> 01:22:26.980
stacked.

1182
01:22:26.980 --> 01:22:31.110
And remember those are the segment sizes.

1183
01:22:31.110 --> 01:22:33.510
Some of these are assembled in the factory.

1184
01:22:33.080 --> 01:22:35.346
Those are the so-called factory joints.

1185
01:22:35.119 --> 01:22:40.052
And then were these come together that's the
so-called field joint, and that's the joint

1186
01:22:39.000 --> 01:22:42.330
that failed in the Challenger accident.

1187
01:22:42.330 --> 01:22:49.050
This gives you a sense of the size of those
solid rocket motors in the way the solid fuel

1188
01:22:49.050 --> 01:22:49.583
is put in.

1189
01:22:49.570 --> 01:22:54.360
And they do all of these tests to look for
the roundness of the motor and the flatness

1190
01:22:54.360 --> 01:22:57.270
of the propellant.

1191
01:22:57.270 --> 01:22:59.840
Yeah?

1192
01:22:59.840 --> 01:23:01.650
Is that the fuel itself?

1193
01:23:01.650 --> 01:23:02.260
It is.

1194
01:23:02.260 --> 01:23:07.420
Although, what confuses me about this is I'm
not sure which segment this is because most

1195
01:23:07.420 --> 01:23:14.420
of the fuel is actually put in with a star
pattern in it and they actually shape the

1196
01:23:14.820 --> 01:23:20.090
way it's loaded so that you shape the thrust
profile.

1197
01:23:20.090 --> 01:23:27.090
And I've not been able to get a good explanation
of why that is not the case here.

1198
01:23:28.320 --> 01:23:35.030
In any case, this is now the process where
they lift one segment, they put it down on

1199
01:23:35.030 --> 01:23:35.896
top of another.

1200
01:23:35.869 --> 01:23:38.690
Of course, all of these are hazardous activities.

1201
01:23:38.690 --> 01:23:44.210
And nobody is allowed, except for the critical
personnel, nobody's allowed in the VAB when

1202
01:23:44.210 --> 01:23:48.449
they're doing this just in case there is a
problem.

1203
01:23:48.449 --> 01:23:55.449
And then they actually put all of these bolts
in to join up the field joint.

1204
01:23:56.000 --> 01:24:03.000
And now, of course, after Challenger we have
a new and improved O ring configuration.

1205
01:24:05.699 --> 01:24:12.570
Now we have the two solid rocket boosters
sitting on the mobile launch platform.

1206
01:24:12.570 --> 01:24:19.570
And, again, you can see you have to design
all of these platforms so you have access.

1207
01:24:20.260 --> 01:24:24.010
Now, the external tank we talked about.

1208
01:24:24.010 --> 01:24:25.780
This is in [UNINTELLIGIBLE].

1209
01:24:25.780 --> 01:24:32.260
This has actually been damaged, not too heavily,
but it did suffer damage from Katrina.

1210
01:24:32.260 --> 01:24:34.750
This is the oxygen tank upfront.

1211
01:24:34.750 --> 01:24:39.010
Notice how small this is compared to this
is the big hydrogen tank.

1212
01:24:39.010 --> 01:24:44.750
And then this is actually the front side,
but this is then turned around and the two

1213
01:24:44.750 --> 01:24:48.840
are joined together inside the outer shell.

1214
01:24:48.840 --> 01:24:55.840
And, of course, the solids are joined to the
external tank, the orbiter is joined to the

1215
01:24:58.280 --> 01:25:04.199
external tank, so basically the external tank
needs a strong back mechanism inside it because

1216
01:25:04.199 --> 01:25:07.465
that's ultimately what's tying the whole stack
together.

1217
01:25:07.449 --> 01:25:13.750
And the trust from the solids and the thrust
from the main engines, ultimately they're

1218
01:25:13.750 --> 01:25:16.283
linked together through the external tanks.

1219
01:25:15.750 --> 01:25:22.510
So the tanks themselves, the hydrogen and
oxygen tanks don't have a lot of beefy structure.

1220
01:25:22.510 --> 01:25:27.260
But going through this is a very heavy structure.

1221
01:25:27.260 --> 01:25:28.300
Yeah?

1222
01:25:28.300 --> 01:25:35.300
The hydrogen tank there is about the diameter
of the overall structure?

1223
01:25:36.739 --> 01:25:37.179
Yeah.

1224
01:25:37.179 --> 01:25:39.449
That gives another idea of the scale.

1225
01:25:39.449 --> 01:25:46.310
This is cleaning and polishing inside the
big hydrogen tank.

1226
01:25:46.310 --> 01:25:53.310
I mean, again, the scale of all of this, it's
important to get a sense of what's involved

1227
01:25:54.010 --> 01:25:56.889
in taking care of these vehicles.

1228
01:25:56.889 --> 01:26:03.659
Do you know if they actually had to go in
and scrub it by hand?

1229
01:26:03.659 --> 01:26:04.560
I guess.

1230
01:26:04.560 --> 01:26:06.800
I mean the scrubbing is only part of it.

1231
01:26:06.800 --> 01:26:12.940
The inspection is the really critical thing,
to see if there is anything that's not quite

1232
01:26:12.940 --> 01:26:13.630
right.

1233
01:26:13.630 --> 01:26:20.630
One thing that's interesting, the use of liquid
oxygen, liquid hydrogen is wanted so much

1234
01:26:23.639 --> 01:26:25.639
because of its higher performance.

1235
01:26:25.489 --> 01:26:31.800
But, on the other hand, if you would do something
like liquid oxygen and kerosene you would

1236
01:26:31.800 --> 01:26:37.330
get a much smaller tank or some other propellant.

1237
01:26:37.330 --> 01:26:40.300
And there is a tradeoff.

1238
01:26:40.300 --> 01:26:45.869
I think today people are realizing, especially
from the Russians, the Russians don't really

1239
01:26:45.869 --> 01:26:47.069
use liquid hydrogen.

1240
01:26:45.920 --> 01:26:49.720
You get a lower ISP but your tanks become
so much smaller to deal with.

1241
01:26:49.060 --> 01:26:52.469
And hydrogen is very hard to deal with.

1242
01:26:52.469 --> 01:26:57.290
It's very hard to find the hydrogen level,
and hydrogen is very hard to deal with.

1243
01:26:57.290 --> 01:26:59.570
My second flight, do you remember?

1244
01:26:59.570 --> 01:27:04.530
That was the one with the hydrogen leaks,
remember that?

1245
01:27:04.530 --> 01:27:06.869
We were supposed to launch in May of 1990.

1246
01:27:06.869 --> 01:27:08.300
And we went down.

1247
01:27:08.300 --> 01:27:14.489
And before they fill the system they do a
helium leak check.

1248
01:27:14.489 --> 01:27:19.422
And, of course, helium, for those of you who
have worked with vacuum systems, helium will

1249
01:27:18.290 --> 01:27:19.623
leak through anything.

1250
01:27:19.389 --> 01:27:25.150
And, if the system is tight against helium,
they figure it is tight.

1251
01:27:25.150 --> 01:27:28.283
The problem is that that's done at ambient
temperature.

1252
01:27:28.239 --> 01:27:35.170
And, when you fill it with the cryogenic hydrogen,
everything contracts.

1253
01:27:35.170 --> 01:27:42.170
And so things which were vacuum-tight at ambient
temperature are not always vacuum-tight.

1254
01:27:43.679 --> 01:27:49.400
But the problem is you don't know that until
you fill it, which is only done a few hours

1255
01:27:49.400 --> 01:27:51.790
before a launch.

1256
01:27:51.790 --> 01:27:53.523
So, we had gone down to the Cape.

1257
01:27:53.230 --> 01:27:55.199
We were in medical quarantine.

1258
01:27:55.199 --> 01:28:01.619
And we just got the message about six hours
before launch there's a hydrogen leak, launch

1259
01:28:01.619 --> 01:28:03.619
is scrubbed.

1260
01:28:03.619 --> 01:28:06.210
They did some checks.

1261
01:28:06.210 --> 01:28:07.730
They drained the tank.

1262
01:28:07.730 --> 01:28:10.800
They did another helium leak check.

1263
01:28:10.800 --> 01:28:12.780
It was fine.

1264
01:28:12.780 --> 01:28:14.313
We had gone back to Houston.

1265
01:28:13.940 --> 01:28:15.239
We came back.

1266
01:28:15.239 --> 01:28:17.139
The same thing happened.

1267
01:28:17.139 --> 01:28:19.739
How long did it take?

1268
01:28:19.739 --> 01:28:23.900
Well, in the end, we made six trips over the
course of six months.

1269
01:28:23.900 --> 01:28:25.966
And we didn't launch until December.

1270
01:28:25.820 --> 01:28:31.070
And, actually, another one of the shuttles
also had a hydrogen leak.

1271
01:28:31.070 --> 01:28:32.880
They actually alternated us.

1272
01:28:32.880 --> 01:28:34.830
They pulled us off the launch pad.

1273
01:28:34.830 --> 01:28:36.619
They put somebody else on.

1274
01:28:36.619 --> 01:28:42.900
I mean what had happened was they had somewhat
changed the procedure of installing some O

1275
01:28:42.900 --> 01:28:48.570
rings in these big hydrogen lines, and it
required a process where the workers were

1276
01:28:48.570 --> 01:28:51.780
actually working in an area where they couldn't
see.

1277
01:28:51.780 --> 01:28:57.060
And the O rings were being installed slightly
wrong.

1278
01:28:57.060 --> 01:29:01.739
But it was just terribly difficult to track
that down.

1279
01:29:01.739 --> 01:29:06.210
So, yeah, there are a lot of problems using
cryogenic fuel.

1280
01:29:06.210 --> 01:29:12.650
Now, the other thing is if you have a fully
staged vehicle with a separate first and second

1281
01:29:12.650 --> 01:29:19.650
stage, one of the things that you learn in
rocket propulsion classes is that in the first

1282
01:29:20.190 --> 01:29:24.260
stage the specific impulse is not nearly as
important.

1283
01:29:24.260 --> 01:29:26.993
What's really important is to get a lot of
thrust.

1284
01:29:26.849 --> 01:29:32.340
In your upper stages having a high ISP becomes
much more important in terms of the payload

1285
01:29:32.340 --> 01:29:33.406
that you can carry.

1286
01:29:33.400 --> 01:29:39.290
So, if you had a fully staged vehicle, and,
in fact, that's the way Saturn worked.

1287
01:29:39.290 --> 01:29:44.423
The first stage of Saturn was kerosene and
liquid oxygen and the upper stages were cryogenic

1288
01:29:44.139 --> 01:29:46.929
with hydrogen and oxygen just for that reason.

1289
01:29:46.929 --> 01:29:48.560
OK, let's move on.

1290
01:29:48.560 --> 01:29:55.560
Now we have the external tank, again, suspended
in the vertical assembly building.

1291
01:29:55.800 --> 01:30:01.469
That's lifted up and joined between the two
SRBs.

1292
01:30:01.469 --> 01:30:08.469
This is the feed line where the oxygen comes
down and this is where these two feeds lines,

1293
01:30:12.360 --> 01:30:13.599
this is the hydrogen.

1294
01:30:13.599 --> 01:30:20.599
And then the orbiter has two corresponding
feed ports where the hydrogen and oxygen comes

1295
01:30:21.199 --> 01:30:22.590
into the engine.

1296
01:30:22.590 --> 01:30:27.800
And, actually, when you fill the tank on the
pad, you actually put the hydrogen and oxygen

1297
01:30:27.800 --> 01:30:29.170
into the orbiter.

1298
01:30:29.170 --> 01:30:33.719
And it flows from the orbiter back then into
the external tank.

1299
01:30:33.719 --> 01:30:38.760
And it was on this oxygen fitting from the
foam that they put around this, was what fell

1300
01:30:38.760 --> 01:30:44.290
off in the recent Discovery flight where they
did get a big piece of foam.

1301
01:30:44.290 --> 01:30:46.460
OK, so now we go back.

1302
01:30:46.460 --> 01:30:50.660
Remember we brought the orbiter over into
the vertical assembly building?

1303
01:30:50.199 --> 01:30:55.599
Now, you put this strong back to hold the
orbiter.

1304
01:30:55.599 --> 01:30:57.399
And this is really spectacular.

1305
01:30:56.560 --> 01:31:02.199
I mean you lift the whole orbiter up off the
ground and tilt it up.

1306
01:31:02.199 --> 01:31:06.989
And you basically hang it and lower it.

1307
01:31:06.989 --> 01:31:13.989
And these are big pieces of equipment and
yet you need millimeters of accuracy.

1308
01:31:18.330 --> 01:31:25.230
So, very skilled crane operators, to say the
least.

1309
01:31:25.230 --> 01:31:32.230
Now we have the orbiter and the strong back
laid down in position and all of the mating

1310
01:31:33.400 --> 01:31:34.510
is done.

1311
01:31:34.510 --> 01:31:37.239
And we're on the pad.

1312
01:31:37.239 --> 01:31:43.520
Excuse me, we're on the mobile launch platform
and they put the crawler transporter underneath

1313
01:31:43.520 --> 01:31:50.520
it and then they roll it on these specially
prepared pads which have very, I don't know

1314
01:31:50.719 --> 01:31:55.070
how deep it goes into the ground, but this
is heavy river gravel.

1315
01:31:55.070 --> 01:32:01.080
Most of the boulders are about the size of
your fist, but after one or two trips of the

1316
01:32:01.080 --> 01:32:03.946
orbiter it's crushed down to the size of pea
gravel.

1317
01:32:03.810 --> 01:32:06.410
And then they have to replace it with new
stuff.

1318
01:32:05.800 --> 01:32:10.333
And, of course, as you're going out to the
pad, when you're rolling up to the launch

1319
01:32:10.310 --> 01:32:13.040
pad, you're actually going up at an angle.

1320
01:32:13.040 --> 01:32:19.199
And so this whole system, you can see the
crawlers down here, each one of these treads,

1321
01:32:19.199 --> 01:32:21.750
each single piece of the tread weighs a ton.

1322
01:32:21.750 --> 01:32:27.040
Just to give you a sense, it goes about one
or two miles per hour top speed.

1323
01:32:27.040 --> 01:32:29.239
It takes hours to get out there.

1324
01:32:29.239 --> 01:32:34.199
And it has to be capable of staying level
to within a few degrees, even as you're climbing

1325
01:32:34.199 --> 01:32:38.150
the ramp up to the launch platform.

1326
01:32:38.150 --> 01:32:42.090
What are those things supporting the [UNINTELLIGIBLE]?

1327
01:32:42.090 --> 01:32:47.280
The whole stack is basically sitting on the
two SRBs.

1328
01:32:47.280 --> 01:32:50.730
The skirts of the SRBs is taking the weight.

1329
01:32:50.730 --> 01:32:57.730
These are the fuel inputs which are connected
through the other side where the hydrogen

1330
01:32:58.590 --> 01:33:00.880
and the oxygen run into the shuttle.

1331
01:33:00.880 --> 01:33:05.080
And, from there, the way I showed you before,
it goes into the external tank.

1332
01:33:04.570 --> 01:33:06.889
Did they also keep it tilted back?

1333
01:33:06.889 --> 01:33:10.070
Did it have the tendency to [UNINTELLIGIBLE]?

1334
01:33:10.070 --> 01:33:14.500
Each of the SRBs has four bolts.

1335
01:33:14.500 --> 01:33:21.219
Actually, they give us, as a souvenir after
a flight, they give us the big nuts that are

1336
01:33:21.219 --> 01:33:23.679
explosive bolts.

1337
01:33:23.679 --> 01:33:27.219
There are eight, four on each of the SRBs.

1338
01:33:27.219 --> 01:33:33.920
And, essentially, that's what gives it its
stability.

1339
01:33:33.920 --> 01:33:38.849
Again, this is a hill.

1340
01:33:38.849 --> 01:33:43.340
It's a little hard to see the perspective,
but keeping the whole thing steady.

1341
01:33:43.340 --> 01:33:49.610
And we talked about how you can see this track
here where the payload change-out room eventually

1342
01:33:49.610 --> 01:33:55.400
could come around and cover the shuttle to
give it protection.

1343
01:33:55.400 --> 01:33:58.969
This is actually going up the hill to get
up.

1344
01:33:58.969 --> 01:34:01.820
And it's just a pretty picture that I like.

1345
01:34:01.820 --> 01:34:03.460
And here we are.

1346
01:34:03.460 --> 01:34:10.460
This is nice because you have both shuttles
on the launch pad.

1347
01:34:10.710 --> 01:34:14.170
This is a big water tower.

1348
01:34:14.170 --> 01:34:21.170
In order to protect the launch pad against
flame damage, and also to protect the shuttle

1349
01:34:23.949 --> 01:34:30.320
against acoustic effects, they actually get
a shockwave when you ignite the engines which

1350
01:34:30.320 --> 01:34:35.260
can bounce back and do some damage.

1351
01:34:35.260 --> 01:34:42.260
Shortly, about 15 seconds before T zero, they
open up the valves.

1352
01:34:44.080 --> 01:34:48.250
And all that water flows with little jets.

1353
01:34:48.250 --> 01:34:53.383
If you've seen pictures of a launch, sometimes
they show that as part of the launch sequence.

1354
01:34:52.360 --> 01:34:58.290
In fact, in another class, I will show you
some of the details of an actual launch picture.

1355
01:34:58.290 --> 01:35:01.989
That's the water deluge, and that goes for
about 30 seconds.

1356
01:35:01.989 --> 01:35:08.179
And that cushions the acoustic load reflected
back to the shuttle.

1357
01:35:08.179 --> 01:35:11.320
OK, that's enough pictures on the pad.

1358
01:35:11.320 --> 01:35:15.090
Oh, I know what I wanted to show.

1359
01:35:15.090 --> 01:35:18.530
This is called the white room.

1360
01:35:18.530 --> 01:35:20.263
And that's how the crew goes in.

1361
01:35:19.960 --> 01:35:22.590
You take an elevator up to here.

1362
01:35:22.590 --> 01:35:26.040
And then that actually joins up with the hatch.

1363
01:35:26.040 --> 01:35:29.150
So the hatch is sitting open.

1364
01:35:29.150 --> 01:35:34.530
And you put on your parachutes and the last
few pieces of equipment to get in.

1365
01:35:34.530 --> 01:35:36.810
And this is a view inside the white room.

1366
01:35:36.810 --> 01:35:42.030
This is, I guess, from our last flight in
1996.

1367
01:35:42.030 --> 01:35:48.139
And, when you go out on launch day, the big
thing that you notice that's different is

1368
01:35:48.139 --> 01:35:52.770
there are very few people on the pad, only
the essential personnel.

1369
01:35:52.770 --> 01:35:57.703
And the whole stack is creaking because it's
now filled with the cryogens and everything

1370
01:35:57.599 --> 01:36:03.369
is shrunk and it's sort of alive in a very
strange way.

1371
01:36:03.369 --> 01:36:06.050
So, we talked about the mission profile.

1372
01:36:06.050 --> 01:36:08.520
I won't deal with this.

1373
01:36:08.520 --> 01:36:15.520
And I do want to talk about some of the shuttle
aborts, but we will do that another time because

1374
01:36:17.360 --> 01:36:20.070
I want to get finished with the slides.

1375
01:36:20.070 --> 01:36:26.190
I did want to show you, after Challenger they
introduced a bailout.

1376
01:36:26.190 --> 01:36:33.190
We did mention that the basic survivability
for the crew requires an intact orbiter.

1377
01:36:34.579 --> 01:36:40.020
It used to be that it needed an intact orbiter
landing on the ground or ditching in the ocean,

1378
01:36:40.020 --> 01:36:45.420
which was kind of an unlikely survivability
because you're going to hit the ocean at 200

1379
01:36:45.420 --> 01:36:47.440
knots and probably break up.

1380
01:36:47.440 --> 01:36:54.440
So now there are circumstances where you can
lose more than one engine during launch or

1381
01:36:54.880 --> 01:37:01.000
you might have to do an emergency de-orbit
where you basically can be flying along at

1382
01:37:01.000 --> 01:37:06.760
40,000 feet stably but with no place to land.

1383
01:37:06.760 --> 01:37:13.150
And so that's really the only situation which
the bailout system protects you against, but

1384
01:37:13.150 --> 01:37:16.610
there is a collapsible poll.

1385
01:37:16.610 --> 01:37:21.543
The reason for that is because the aerodynamic
studies show that if you just jumped out of

1386
01:37:21.420 --> 01:37:28.420
the open hatch with a parachute the airflow
would carry you back on top of the wing and

1387
01:37:30.130 --> 01:37:34.219
you'd hit the OMS pod, and that would not
be a good deal.

1388
01:37:34.219 --> 01:37:40.530
So, you actually hook yourself to this escape
poll.

1389
01:37:40.530 --> 01:37:46.650
And that takes you down below the wing, and
then you can open the parachute.

1390
01:37:46.650 --> 01:37:52.429
And we actually practiced this where you go
out into a swimming pool using the escape

1391
01:37:52.429 --> 01:37:53.260
poll.

1392
01:37:53.260 --> 01:38:00.260
These are some actual tests conducted by Army
parachutists in, I think, a 141 Transport.

1393
01:38:00.510 --> 01:38:04.880
The system has been tested in flight, although
never with the shuttle.

1394
01:38:04.880 --> 01:38:11.880
And that's the test where they have a simulated
hatch and you basically jump out into the

1395
01:38:13.810 --> 01:38:15.599
swimming pool.

1396
01:38:15.599 --> 01:38:19.139
Once again, into the white room.

1397
01:38:19.139 --> 01:38:21.550
You can see the hatch out here.

1398
01:38:21.550 --> 01:38:25.216
And that's the last thing that they'll do,
is they close the hatch.

1399
01:38:25.139 --> 01:38:30.969
Then they pressurize the shuttle by about
1.5 PSI just to make sure that it has pressure

1400
01:38:30.969 --> 01:38:33.449
integrity before a launch.

1401
01:38:33.449 --> 01:38:37.389
And then we launch.

1402
01:38:37.389 --> 01:38:43.510
As you can see, you're burning hydrogen and
oxygen in the main engines.

1403
01:38:43.510 --> 01:38:47.199
What's coming out there is just hot steam,
not very visible.

1404
01:38:47.199 --> 01:38:52.949
Most of the smoke, the noise and everything
come from the solid rocket boosters.

1405
01:38:52.949 --> 01:38:57.239
However, you do need these engines.

1406
01:38:57.239 --> 01:39:04.239
In fact, people have calculated that if you
tried to take off without these main engines

1407
01:39:04.940 --> 01:39:09.806
pushing up on the shuttle that the attachment
between the shuttle and the external tank

1408
01:39:09.670 --> 01:39:12.659
would probably fail.

1409
01:39:12.659 --> 01:39:18.290
Each of the main engines is about, well, it's
a half a million pounds of thrust in vacuum.

1410
01:39:18.290 --> 01:39:21.719
It's slightly under 400,000 pounds at sea
level.

1411
01:39:21.719 --> 01:39:26.550
You've got a little over a million pounds
coming from the main engines, but these are

1412
01:39:26.550 --> 01:39:30.349
putting out almost three million pounds a
piece.

1413
01:39:30.349 --> 01:39:35.149
So, most of your early thrusts in the first
two minutes are coming from the solid rocket

1414
01:39:34.869 --> 01:39:36.280
boosters.

1415
01:39:36.280 --> 01:39:37.880
And it's a pretty rough ride.

1416
01:39:37.440 --> 01:39:41.409
I mean there's a lot of vibration.

1417
01:39:41.409 --> 01:39:48.409
When you go through mach 1, which is max Q,
maximum dynamic pressure, the vibrations are

1418
01:39:49.179 --> 01:39:51.540
even more pronounced.

1419
01:39:51.540 --> 01:39:56.140
The first time on my first flight, I really
thought the wings were going to come off,

1420
01:39:54.960 --> 01:39:56.560
there was so much vibration.

1421
01:39:56.179 --> 01:39:58.889
But, of course, they don't.

1422
01:39:58.889 --> 01:40:01.449
But I'd love to get a hold of it.

1423
01:40:01.449 --> 01:40:08.389
I actually saw a high-speed, well, a slow
motion picture actually looking at the tail,

1424
01:40:08.389 --> 01:40:09.655
as you go through max Q.

1425
01:40:09.530 --> 01:40:13.396
And you can actually see the tail fluttering
back and forth like that.

1426
01:40:12.659 --> 01:40:18.369
I mean the aerodynamic loads on the vehicle
during ascent are significant.

1427
01:40:18.369 --> 01:40:25.369
And you do actually have to move your elevons
to what's called load relief in order to take

1428
01:40:26.510 --> 01:40:29.980
the stress off that.

1429
01:40:29.980 --> 01:40:33.139
I really like this.

1430
01:40:33.139 --> 01:40:39.630
It gives a sense of the power that you're
sitting on top of to get up there.

1431
01:40:39.630 --> 01:40:43.610
And that's just a nice picture of riding the
fire.

1432
01:40:43.610 --> 01:40:48.190
OK, so you get up in orbit and you drop the
external tank.

1433
01:40:48.190 --> 01:40:55.190
And, although now they're going out of their
way to take even better close-ups of the tank

1434
01:40:55.880 --> 01:40:57.560
to look at the foam shedding.

1435
01:40:57.560 --> 01:41:03.280
We've been doing that, in fact, throughout
the history.

1436
01:41:03.280 --> 01:41:08.146
Now they especially time the launch so that
you're guaranteed to drop the external tank

1437
01:41:07.880 --> 01:41:09.680
with good lighting conditions.

1438
01:41:09.369 --> 01:41:12.920
That didn't used to be a constraint to launch
but it is now.

1439
01:41:12.920 --> 01:41:17.429
You can also, by the way, see how the atmosphere
quickly fades out into space.

1440
01:41:17.429 --> 01:41:23.250
And that's a telephoto so it actually makes
the atmosphere look even thicker than it really

1441
01:41:23.250 --> 01:41:24.159
looks.

1442
01:41:24.159 --> 01:41:28.920
OK, so there is the orbiter in space.

1443
01:41:28.920 --> 01:41:32.929
That was actually after it had delivered a
payload.

1444
01:41:32.929 --> 01:41:39.500
This was taken from the space station.

1445
01:41:39.500 --> 01:41:45.190
And just a quick reminder of all the different
things that we've used the orbiter for.

1446
01:41:45.190 --> 01:41:48.150
Launching satellites, you've seen that picture.

1447
01:41:48.150 --> 01:41:54.530
This is a payload assist module to take the
satellite from the shuttle orbit up to geosynchronous

1448
01:41:54.530 --> 01:41:57.540
transfer orbit.

1449
01:41:57.540 --> 01:42:03.730
We have used it extensively for satellite
repair in orbit.

1450
01:42:03.730 --> 01:42:09.889
This is the Intelsat where it was put into
orbit by an expendable rocket, but into a

1451
01:42:09.889 --> 01:42:13.929
bad orbit because of underperformance.

1452
01:42:13.929 --> 01:42:17.750
And they managed to get it into a shuttle
compatible orbit.

1453
01:42:17.750 --> 01:42:20.840
And I won't go through the whole history.

1454
01:42:20.840 --> 01:42:25.510
Why there happened to be three people out
there is a whole story in itself.

1455
01:42:25.510 --> 01:42:27.369
This is one of the satellites.

1456
01:42:27.369 --> 01:42:33.139
Again, the satellites were put into orbit
by the shuttle.

1457
01:42:33.139 --> 01:42:38.139
And the shuttle deployment was fine, but the
payload assist module, which you saw before,

1458
01:42:38.110 --> 01:42:39.579
did not perform properly.

1459
01:42:39.579 --> 01:42:44.280
And so the two satellites were stranded in
a useless orbit.

1460
01:42:44.280 --> 01:42:46.746
We actually brought them back to the ground.

1461
01:42:46.579 --> 01:42:52.030
They were refurbished and re-launched again
on expendable rockets.

1462
01:42:52.030 --> 01:42:59.030
The shuttle has also been used as a space
station with the space lab on in the inside

1463
01:42:59.389 --> 01:43:01.522
to carry out scientific experiments.

1464
01:43:01.159 --> 01:43:05.900
This is a large pressurized module which is
put into the cargo bay.

1465
01:43:05.900 --> 01:43:12.900
And the original idea, as Professor Cohen
mentioned, was you could just take your laboratory

1466
01:43:13.590 --> 01:43:20.489
equipment off the shelf, plug it in here,
120 volts AC power, I guess, and it would

1467
01:43:20.489 --> 01:43:22.422
be just like working on the ground.

1468
01:43:22.250 --> 01:43:23.929
Well, it never was.

1469
01:43:23.929 --> 01:43:30.929
But, having said that, I think the space lab
program, as a whole, was extremely successful.

1470
01:43:31.920 --> 01:43:36.040
And then it's been used to service the Mir
Space Station.

1471
01:43:36.040 --> 01:43:41.510
We certainly added several years of useful
life to the Mir Station because we could carry

1472
01:43:41.510 --> 01:43:44.969
up a lot more equipment than the Russians
could themselves.

1473
01:43:44.969 --> 01:43:51.969
And that also gave us an opportunity to get
some US astronauts on long duration space

1474
01:43:52.090 --> 01:43:54.440
missions.

1475
01:43:54.440 --> 01:44:00.060
And then, as you all know, we're using the
shuttle to construct the International Space

1476
01:44:00.060 --> 01:44:02.050
Station.

1477
01:44:02.050 --> 01:44:07.429
And hopefully we'll get more of it built before
too long.

1478
01:44:07.429 --> 01:44:14.429
The shuttle is also an excellent platform
for performing EVAs, space walks.

1479
01:44:15.190 --> 01:44:20.030
And that's a picture of when we went up and
repaired the Hubble Space Telescope.

1480
01:44:20.030 --> 01:44:27.030
I cannot overestimate the capability that
the shuttle gives us as a work platform in

1481
01:44:29.409 --> 01:44:30.940
orbit.

1482
01:44:30.940 --> 01:44:36.300
We can do this sort of complex EVA activity
on the Space Station, but once we retire the

1483
01:44:36.300 --> 01:44:40.340
shuttle we've essentially lost that capability.

1484
01:44:40.340 --> 01:44:46.369
To have the manipulator arm and to be able
to use people and the robotic arm to move

1485
01:44:46.369 --> 01:44:51.510
equipment around, it's just a very powerful
work platform.

1486
01:44:51.510 --> 01:44:58.510
That's one of my favorite pictures floating
up there.

1487
01:45:01.349 --> 01:45:07.199
This is a pretty picture of firing the orbiter
maneuvering engines just to start your descent

1488
01:45:07.199 --> 01:45:09.159
into the atmosphere.

1489
01:45:09.159 --> 01:45:14.340
Despite the fact that you're going at 18,000
miles an hour, you only have to slow down

1490
01:45:14.340 --> 01:45:21.340
by a few hundred feet per second in order
to lower your perigee down to essentially

1491
01:45:21.440 --> 01:45:26.240
the surface of the earth so that half an orbit
later you intersect with the atmosphere.

1492
01:45:25.829 --> 01:45:32.829
And, of course, that produces the aerodynamic
heating which you can see on the outside.

1493
01:45:33.429 --> 01:45:35.229
This is looking out to the front.

1494
01:45:34.920 --> 01:45:38.060
That's kind of a dull glow.

1495
01:45:38.060 --> 01:45:44.070
It starts out as a deep red and then it gets
orange and yellow and finally white on the

1496
01:45:44.070 --> 01:45:44.603
outside.

1497
01:45:44.219 --> 01:45:47.849
The most spectacular thing, you know, you're
a meteor.

1498
01:45:47.849 --> 01:45:53.329
This is a picture that was taken from Houston.

1499
01:45:53.329 --> 01:45:58.810
This is at about 250,000 feet at about mach
12 on the way to a landing at the Kennedy

1500
01:45:58.810 --> 01:45:59.739
Space Center.

1501
01:45:59.739 --> 01:46:03.050
The shuttle is flying like this.

1502
01:46:03.050 --> 01:46:07.719
If you look up at the overhead windows, you
can actually look back into the wake.

1503
01:46:07.719 --> 01:46:12.519
And this is really spectacular because you
have these different colors, and it's sort

1504
01:46:12.010 --> 01:46:13.276
of shimmering around.

1505
01:46:13.210 --> 01:46:19.969
And every once in a while, when I would be
looking at this, you'd see a big bright light.

1506
01:46:19.969 --> 01:46:23.102
And I would think boy, I hope that was nothing
important.

1507
01:46:23.070 --> 01:46:27.480
[LAUGHTER] What people said it probably was
were little bits of gap filler.

1508
01:46:27.480 --> 01:46:32.146
You may have heard that on the last flight
they discovered that some gap fillers were

1509
01:46:31.210 --> 01:46:32.210
protruding.

1510
01:46:32.210 --> 01:46:37.110
And so Steve Robinson went around and actually
pulled some of them out.

1511
01:46:37.110 --> 01:46:42.170
But they've probably been doing that the whole
time and just have come off.

1512
01:46:42.170 --> 01:46:49.170
I mean this little point where you have the
convergence of the shockwaves, this is about

1513
01:46:49.280 --> 01:46:54.880
10,000 degrees Fahrenheit, that's the surface
temperature of the sun.

1514
01:46:54.880 --> 01:46:58.550
It's a spectacular visual view.

1515
01:46:58.550 --> 01:47:05.550
And then, again, at this point we're just
going subsonic flying like a glider and ready

1516
01:47:08.980 --> 01:47:09.846
for touchdown.

1517
01:47:09.710 --> 01:47:16.710
So, I hope that gives you some sense visually
of what goes on in the course of a shuttle

1518
01:47:19.540 --> 01:47:26.540
flight with an emphasis on the maintenance
operations.

1519
01:47:26.630 --> 01:47:33.630
Without appreciating how complex it is to
operate this system, I think it's hard to

1520
01:47:35.349 --> 01:47:41.780
really make the link between the original
concept and the difficulties we've had in

1521
01:47:41.780 --> 01:47:47.989
getting the shuttle to perform in terms of
the turnaround maintainability.

1522
01:47:47.989 --> 01:47:54.989
So, again, just wrapping up, that's kind of
my farewell picture, the shuttle was an amazingly

1523
01:47:58.760 --> 01:48:01.090
ambitious concept.

1524
01:48:01.090 --> 01:48:08.090
And, I think, what has been astounding is
how well the shuttle has been able to perform

1525
01:48:08.340 --> 01:48:13.270
and do all the things that it was designed
to do in terms of the satellite launching

1526
01:48:13.270 --> 01:48:19.679
and being used as a science platform, performing
EVA, repairing satellites, building space

1527
01:48:19.679 --> 01:48:20.280
stations.

1528
01:48:20.280 --> 01:48:26.969
It has given us experience and capability
to learn how to do things in earth orbit which

1529
01:48:26.969 --> 01:48:28.460
we never had before.

1530
01:48:28.460 --> 01:48:34.040
And, as I say, we may well miss them once
we retire the shuttle.

1531
01:48:34.040 --> 01:48:40.480
But where we really did get it wrong, and
this will be one of the things that we'll

1532
01:48:40.480 --> 01:48:44.810
look at when we deal with the individual subsystems,
is in the operations.

1533
01:48:44.810 --> 01:48:51.810
It turned out to be a lot more complex, expensive
and delicate to operate than had been anticipated.

1534
01:48:55.110 --> 01:49:02.110
So hopefully there will come a time when we
set out to design another reusable vehicle,

1535
01:49:04.560 --> 01:49:07.110
possibly a reusable winged vehicle.

1536
01:49:07.110 --> 01:49:11.679
And I think a lot of what we've learned from
the shuttle will be folded into that.

1537
01:49:11.679 --> 01:49:17.530
It still is a question of how re-usable the
next crew exploration vehicle, the CEV will

1538
01:49:17.530 --> 01:49:19.159
be.

1539
01:49:19.159 --> 01:49:24.050
Re-usability has been put in as a requirement,
but that remains to be seen.

1540
01:49:24.050 --> 01:49:29.183
And certainly the experience that we've gotten
from the shuttle is going to make people look

1541
01:49:29.000 --> 01:49:35.809
really, really closely at what assumptions
we're making about the reusability whenever

1542
01:49:35.809 --> 01:49:37.690
we do this again.

1543
01:49:37.690 --> 01:49:38.760
OK.

1544
01:49:38.760 --> 01:49:45.760
Next Tuesday will be the last in kind of the
conceptual part of what we're doing.

1545
01:49:47.540 --> 01:49:54.540
Professor John Logsdon from George Washington
University is a very well known space policy

1546
01:49:54.750 --> 01:49:55.510
analyst.

1547
01:49:55.510 --> 01:50:02.510
He did a seminal study on the Apollo program
and has also written a lot and done a lot

1548
01:50:03.929 --> 01:50:07.230
of research on the origins of the shuttle.

1549
01:50:07.230 --> 01:50:08.820
And so he'll talk to us then.

1550
01:50:08.820 --> 01:50:10.040
Let's see.

1551
01:50:10.040 --> 01:50:15.719
I had promised to post everybody's emails
on the Web, and I got diverted and didn't

1552
01:50:15.719 --> 01:50:16.559
get that done.

1553
01:50:16.559 --> 01:50:23.190
But I will do that before tomorrow, you know,
in terms of forming your teams.

1554
01:50:23.190 --> 01:50:28.949
Put together an idea of what system you would
like to work at.

1555
01:50:28.949 --> 01:50:34.790
If you're not able to form up as part of a
team between now and Tuesday, just give me

1556
01:50:34.790 --> 01:50:36.923
what your own personal preference is.

1557
01:50:36.889 --> 01:50:42.449
And then we can look and see if different
people are interested in the same system.

1558
01:50:42.449 --> 01:50:45.840
We'll let you all know and help you form up
teams.

1559
01:50:45.840 --> 01:50:52.840
I'll make sure your email is there in the
student view.

1560
01:50:54.889 --> 01:51:01.889
[UNINTELLIGIBLE PHRASE] If you've already
formed a group then just turn in something

1561
01:51:04.409 --> 01:51:05.159
as a group.

1562
01:51:05.159 --> 01:51:06.340
That's fine.

1563
01:51:06.340 --> 01:51:13.099
If not, if you haven't hooked up with somebody,
just let us know what system you're interested

1564
01:51:13.099 --> 01:51:17.619
in working at and any ideas you might have
of what you're going to look at.

1565
01:51:17.619 --> 01:51:24.619
Really, this is just a very, very short write-up
essentially to get you started.

1566
01:51:26.090 --> 01:51:30.269
And that way, if you have any questions, we
can talk about it next Tuesday.