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Walt Guy's biography is on the website.

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I hope you've had a chance to look at it.

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I will just say briefly that I guess, of all
the lecturers coming, that Walt is the only

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one who is still actually working actively
for NASA.

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He is head of the Automation, Robotics and
Simulation Division, division chief at the

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Johnson Space Center.

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But that is not what he's talking about there.

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He's talking about the job that he used to
do for about 20 years which was head of environmental

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thermal life support and crew systems.

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And, of course, the crew system includes all
the space suits and the good stuff that I

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was fortunate enough to get to use.

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So I've got a personal debt of thanks to Walt.

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Aaron, I think you wanted to say a couple
of things so I will pass the microphone to

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you.

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Yes, I would like to say a few words about
Walt.

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We've worked together for many years.

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And Walt Guy has the very unique capability
of being not only an outstanding engineer,

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a technical person, but he also has a very
unique capability of being a great or outstanding

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project manager, program manager.

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No matter what task you gave Walt, he could
deliver the product on performance, on schedule

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and on time.

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He has that unique capability.

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And he's done that from the Apollo Program
through the Shuttle Program.

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And I think you're really in for a treat to
hear Walt talk about the environmental control

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systems.

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He has a lot of information to offer you so,
without further ado, let me turn it over to

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Walt.

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Thank you, Aaron.

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As Aaron said, we worked together over several
programs over a long period of time.

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I was noticing the picture.

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I'm sure that wasn't put there for me.

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But my current responsibilities are the robotic
arm you see there.

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That is a shuttle arm.

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Of course there are station arms also.

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Grapple fixture over here on the left.

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And the little jet pack on the tumbling crewman
there is part of my current responsibilities.

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The 20 years that Jeff mentioned, I was responsible
for the development of the Shuttle spacesuit.

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So it was like it was meant for me anyway.

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What I'd like to do is talk about the design.

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I know in the syllabus it said environmental
control systems.

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So where did all the rest of the stuff come
from?

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If you go back in perspective, the Mercury,
Gemini, Apollo Program had the classical thing

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that aerospace calls environmental control
systems.

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It was basically a cabin system.

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It took care of the living quarters for the
crew.

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But in the Shuttle era the responsibility
of that system expanded to include more than

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just the cabin and, thus, the very long hard
to say name.

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These are the subsystem elements of the environmental
thermal control and life support system.

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The first area I am going to -- These are
the areas, the subsystems.

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The first area is the cabin atmospheric revitalization
system.

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This is a long way of saying to take care
of the atmosphere in the cabin.

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Humans are pollutants and this is the system
that takes care of that.

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The cabin atmospheric pressure and composition,
this is obviously to maintain the pressure

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and enough oxygen for breathing.

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The third is the cabin thermal control, and
that is the classical environmental control

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system.

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But, for Shuttle, we've added some functions.

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One is the water and waste management subsystem.

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There are some hygiene functions required,
there are some recharge of the spacesuit's

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backpack, management of the fuel cell water
system, the fuel cells of the electrical power

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supply and provide a lot of extra water.

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Also, the vehicle at this point, has a dedicated
active thermal control system that takes care

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of all of the systems in the vehicle, not
just the cabin systems.

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And then last is the airlock support subsystem.

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This is the EVA crewman's portal to space.

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And so the environmental thermal control and
life support system covers all these areas.

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What I will do is go through each one of those.

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The first is the cabin atmospheric revitalization
system.

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Its functions are CO2 and trace gas removal,
humidity control, environmental cooling and

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atmospheric circulation and ventilation.

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Again, I will talk each about these.

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But I do want to mention that there is a uniqueness
about space and that there is no convection

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so circulation is important.

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Also, because of the fact that there is no
convection, getting rid of the body heat,

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the latent heat requires a ventilation of
the crew.

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So each of these areas ended up as part of
the system design.

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This is an overview silhouette of the Orbiter.

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I will use this throughout the presentation.

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As you can see, part of the system we're talking
about now, the atmospheric revitalization

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system is located upfront where the crew is.

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It is beneath the floor.

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And we will be talking about the systems in
the remainder of the Orbiter as we go along.

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This is a simplified schematic.

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I would like to start at the cabin fans.

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These are redundant.

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Each fan will do the job.

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The next in line is the CO2 scrubber followed
by the cooler, the cabin heat exchanger.

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There is a bypass around that for control
of the amount of cooling that is needed.

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As you are aware, the Shuttle can fly with
few or many crewmen.

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It turns out, as time has gone on, we fly
pretty much a full compliment.

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But the original design was to fly a small
number of crewmen.

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Also, this does give you temperature control.

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The same heat exchanger provides the condensation
of the water from the atmosphere.

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Therefore, you get humidity control.

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And then that is collected.

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The gas continues on.

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It is now chilled and is provided out to the
flight deck and the middeck to the crew.

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Then the gas from the cabin is then drawn
back in through some flight deck avionics

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and back through the fans.

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So this is the basic systems schematic.

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I might pause here a moment to sort of explain
the role of the government in the development

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of the Shuttle.

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As you know, the prime was Rockwell.

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It was their job to build the vehicle.

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But the government philosophy, management
philosophy was to have ownership of the technical

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aspects of the design.

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So we had basically no excuse.

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If it didn't work it wasn't because the contractor
did something wrong.

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We had to have ownership.

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In fact, Aaron, as the project manager, would
probably look to us first as the reason for

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a problem as opposed to Rockwell because we
were the conscience of the program so we should

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have made sure they didn't do it wrong and
provided whatever technical insight to Aaron

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to make sure he made the programmatic decisions
to make sure things were not done wrong.

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Very early in the Shuttle Program, I was responsible
for an engineering organization.

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And that engineering organization wanted to
own the design of the environmental thermal

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control and life support system.

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We acquired a chamber.

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This is a near atmospheric chamber.

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It is a square so it is obviously not shaped
like the Orbiter cabin, but the volume was

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appropriate.

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And it did allow a sealed environment for
testing.

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It would take a couple of PSI delta Ps.

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That's about all it would take.

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We developed a -- [COMMENT FROM HOFFMAN],
No, that was a different one.

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OK.

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We developed an environmental control system
or an atmospheric revitalization control system

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and placed it inside to do early testing.

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As you can see here, this is the fan package.

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The CO2 scrubbers are here.

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Heat exchange package over here.

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And you can tell we're not current in terms
of calendar-wise.

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The CO2 and trace gas removal, the requirements
were to maintain less than 7.6 millimeters

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of mercury.

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This is certainly to provide a habitable environment
for the crew.

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This is higher than sea level but the medics
agreed that that was a completely adequate

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level for CO2.

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The CO2 absorption came from the humidified
cabin gas so the system had to accommodate

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that as a feed stream.

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The absorbent selected was lithium hydroxide.

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The equation was a lithium hydroxide reacted
with the CO2 to produce lithium carbonate,

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water and heat.

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And this was a single use system.

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It turns out that the lithium hydroxide was
an old solution.

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The previous spacecraft had used the same
solution, but pretty much their solution was

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unique purchased production of lithium hydroxide.

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When we entered the Shuttle era, we were hoping
for a long duration.

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And the idea was to use the commercial products
to get away from special production.

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And so we looked around.

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And the Navy was producing a screened special
production run for their submarines.

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So there was a lot of use there.

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And so the production was reasonably upo.

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We decided to use the Navy grade.

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And so we brought it in and put it in the
test bed that I just showed you and did some

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tests, and it didn't work worth a darn.

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You notice the loops here show that our use
of the canister was much more rapid that we

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had hoped for.

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The nice beautiful deep loops here are a process
that we developed to screen the Navy LiOH

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so that we didn't have to create a new production
capability but were able to test the LiOH

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that came off their production line and get
a LiOH that was much more humidity tolerant.

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The key here turned out to be not the chemical
itself but its ability to produce good performance

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over a wide humidity range.

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So we were able to screen that and make that
a viable non-special production run LiOH.

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The lithium hydroxide, I said, was an old
solution.

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All previous spacecraft have been pretty short
mission.

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And even the Shuttle was a short mission.

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But the specification for Shuttle said that
it should have a capability of going 28 days,

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and 28 days is not a short mission, at least
not in Shuttle parlance.

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The engineering part of the organization said,
well, why don't we go with a regenerative

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system?

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SkyLab had just been successfully flown with
a regenerative system, something that wouldn't

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have all this expendables because 28 days
worth of lithium hydroxide for seven crewmen

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fills everything up with lithium hydroxide.

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There is no room for anything else.

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So we began to look at a regenerative system
that could be used.

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Actually, it was proposed as part of the original
Shuttle development.

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But, at that point, the 28-day mission was
considered a special case and the design case

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was the shorter missions.

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And, in fact, there were even projected to
be a lot of short missions.

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The idea that the Shuttle was a space truck.

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It would take stuff up, dump it out and come
home.

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And so the lithium hydroxide was a lighter
system than a regenerative system.

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The lithium hydroxide was placed into the
vehicle as a basic design.

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But, when the Space Lab era came along, we
needed longer missions.

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We flew about four or five times in this 13
to 16 day range, and those missions did require

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a lot of lithium hydroxide.

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And so it was proposed to use an absorbent
that was regenerable, and the one that was

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selected was a solid amine.

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The absorbent is a polymerized ethyleneimine.

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Its designation is RNH, and I don't really
know why.

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The absorption actually comes in, in two steps.

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First there is a reaction with water to create
the Freon.

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And then that is then reactive with the CO2
to give you another free ion, but the CO2

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is now captured.

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The desorption then with the heat and vacuum
gives you back your original amine.

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So if you pack this in a bed, and what we
used was an expanded metal foam heat exchanger

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that you could fill all the holes with the
solid amine and put the passages adjacent

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to each other so that you could use the heat
of absorption to do your desorption on your

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other side.

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And all you would need to do is expose it
to vacuum.

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It was a very simple system.

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It worked fine for the three or four missions.

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I'm not sure how many missions it was used.

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But it was an adjunct.

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It was added in, put onto the floor, and then
it was taken back out when it was no longer

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needed because it was just wasted load.

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Yes.

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For the lithium hydroxide, the product LiCO3,
is that a solid form or a gas form?

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No, it's a solid lithium carbonate.

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And that goes in the canisters that you remove?

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Right.

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When you remove the canister it's a big lump.

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OK.

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Finishing up the CO2 and trace removal, we
go to the trace removal and use the simple

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system of activated charcoal.

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And, in fact, it is packed into the same canister
that the lithium hydroxide is packed into.

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It is a single use.

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There is a configuration, I believe, now operationally
where the entire canister is activated charcoal

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so it can be used for cabin gas cleanup.

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So, if you had an issue that you needed to
clean the cabin up, you could do that with

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a canister just of charcoal.

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The next area is the environmental cooling
and humidity control.

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I mentioned on the schematic that we have
a cabin heat exchanger.

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The front part of the heat exchanger basically
is your reduced cabin gas temperature.

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The backend of the heat exchanger is where
the condensing occurs because we get the gas

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below the dew point and, therefore, the water
drops out.

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The heat exchanger has the characteristic
that, as the water collects at the outlet

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of the heat exchanger, there were some holes
drilled, actually, in the thin passages so

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the water can be sucked out.

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And it has the nickname "slurper." So it slurps
the water out.

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It takes about 2% of the flow.

231
00:16:53,244 --> 00:16:58,669
So, as the cabin fan produces the flow through
the heat exchanger, about 2% is siphoned off

232
00:16:58,704 --> 00:16:59,350
in the slurper.

233
00:16:59,385 --> 00:17:06,350
And that carries the water to the centripetal
water gas separator.

234
00:17:10,589 --> 00:17:13,140
This is a device that basically spins the
airstream.

235
00:17:13,175 --> 00:17:15,230
It's an airstream with water and trained.

236
00:17:15,265 --> 00:17:16,620
It spins the airstream.

237
00:17:16,655 --> 00:17:17,940
The water goes to the outside.

238
00:17:17,975 --> 00:17:23,750
It is collected in a trough and there is a
pitot tube in the trough that the water impinges

239
00:17:23,785 --> 00:17:28,070
on, and we get about a 40 PSI delta head with
that.

240
00:17:28,105 --> 00:17:33,650
It's just a pump basically, a pitot pump.

241
00:17:33,685 --> 00:17:40,150
The atmospheric circulation and ventilation
is the next part of the system.

242
00:17:40,185 --> 00:17:44,190
As you know, we're still in atmospheric revitalization.

243
00:17:44,225 --> 00:17:45,780
There are the redundant fans that I mentioned.

244
00:17:45,815 --> 00:17:48,660
Each fan will do the job.

245
00:17:48,695 --> 00:17:55,660
There is also flight deck and mid deck duct
system.

246
00:17:55,790 --> 00:18:00,830
It looks very complicated but there are only
several points I want to make here.

247
00:18:00,865 --> 00:18:04,390
This is the atmospheric revitalization system
I mentioned before.

248
00:18:04,425 --> 00:18:06,000
As you see, it is below the floor.

249
00:18:06,035 --> 00:18:07,570
This is the mid deck here.

250
00:18:07,605 --> 00:18:08,860
This is the flight deck.

251
00:18:08,895 --> 00:18:12,140
So it's below the floor of the mid deck.

252
00:18:12,175 --> 00:18:16,650
The gas exits the heat exchanger.

253
00:18:16,685 --> 00:18:18,520
It goes up.

254
00:18:18,555 --> 00:18:23,710
There is some aft mid deck ventilation exhaust.

255
00:18:23,745 --> 00:18:29,420
It goes on up to the flight deck and exhausts
on the flight deck.

256
00:18:29,455 --> 00:18:36,420
Also there is a section that goes on the forward
side of the cabin through the forward control

257
00:18:38,040 --> 00:18:44,050
console and blows in the face of the crew.

258
00:18:44,085 --> 00:18:51,050
The return is back through some avionic areas
to provide cooling, and then back down to

259
00:18:53,930 --> 00:18:55,690
the system.

260
00:18:55,725 --> 00:19:01,270
This is a complicated picture, but really
it is a very simple flow system.

261
00:19:01,305 --> 00:19:07,200
This becomes important later in our discussion
because good mixing turned out to be a really

262
00:19:07,235 --> 00:19:08,130
important parameter.

263
00:19:08,165 --> 00:19:12,800
Not just cooling.

264
00:19:12,835 --> 00:19:13,050
OK.

265
00:19:12,920 --> 00:19:13,450
The second.

266
00:19:13,485 --> 00:19:14,650
Remember we had six?

267
00:19:14,685 --> 00:19:16,230
This is the second element.

268
00:19:16,265 --> 00:19:19,850
This is the atmospheric pressure and composition
control.

269
00:19:19,885 --> 00:19:22,470
The first job is the 14.7.

270
00:19:22,505 --> 00:19:29,470
The Shuttle selected sea level, the idea being
we could not have a lot of special designed

271
00:19:32,270 --> 00:19:34,000
equipment.

272
00:19:34,035 --> 00:19:38,030
Shuttle was intended to be a less expensive
spacecraft than the previous ones.

273
00:19:38,065 --> 00:19:44,010
And so a sea level atmosphere gave us no questions
about human survival and gave us a lot of

274
00:19:44,045 --> 00:19:50,270
opportunity for using more standard equipment
and not specially designed equipment.

275
00:19:50,305 --> 00:19:56,890
There was a requirement, though, for a PSIA
total control, but this was only for an emergency

276
00:19:56,925 --> 00:19:57,450
de-orbit.

277
00:19:57,485 --> 00:20:00,610
The problem statement is that you got a hole
in your cabin.

278
00:20:00,645 --> 00:20:03,080
Don't know how you got it but you have it.

279
00:20:03,115 --> 00:20:08,850
And the idea is the system has to be able
to sustain the crew for a de-orbit.

280
00:20:08,885 --> 00:20:13,930
And I don't know who made up the number but
169 minutes is the number.

281
00:20:13,965 --> 00:20:16,490
We have an emergency return, 169 minutes.

282
00:20:16,525 --> 00:20:23,490
The system has to be able to accommodate that
keeping the total pressure at or above 8 PSI.

283
00:20:24,660 --> 00:20:27,770
So there has to be enough flow capability,
enough consumables to do that.

284
00:20:27,805 --> 00:20:32,180
The half-inch hole was a programmatic decision.

285
00:20:32,215 --> 00:20:39,180
I cannot speak for where the number exactly
came from, but it probably had to do with

286
00:20:39,990 --> 00:20:45,600
meteoroid debris kind of analysis that said
what type of hole you could expect.

287
00:20:45,635 --> 00:20:49,760
Anyway, that was the design for the system.

288
00:20:49,795 --> 00:20:56,700
The next aspect or element of the system is
the O2/N2 partial pressure control.

289
00:20:56,735 --> 00:21:02,200
At the total pressure of 14.7, we wanted sea
level which is about 3.2 PSI oxygen.

290
00:21:02,235 --> 00:21:08,280
At the 8 PSI, we wanted it to be survivable
but the oxygen could be less.

291
00:21:08,315 --> 00:21:13,190
Obviously, people live in Denver so that works.

292
00:21:13,225 --> 00:21:18,130
There are also crew breathing masks which
can be used in conjunction with low oxygen

293
00:21:18,165 --> 00:21:19,910
partial pressure.

294
00:21:19,945 --> 00:21:24,110
The cabin had to have both positive and negative
relief.

295
00:21:24,145 --> 00:21:28,880
It had to store the oxygen and nitrogen, and
it had to provide pressurization for the water

296
00:21:28,915 --> 00:21:29,620
management system.

297
00:21:29,655 --> 00:21:34,330
Remember earlier I talked about the more pervasive
requirements?

298
00:21:34,365 --> 00:21:37,750
The water and waste management system now
is placing requirements on the atmospheric

299
00:21:37,785 --> 00:21:42,140
pressure and composition control.

300
00:21:42,175 --> 00:21:49,140
This is a silhouette again where basically
here you see the oxygen tank, which is 3300

301
00:21:51,130 --> 00:21:52,110
PSI oxygen tank.

302
00:21:52,145 --> 00:21:56,150
There are nitrogen tanks on both sides.

303
00:21:56,185 --> 00:22:00,500
These are high pressure tanks all 3300 PSI.

304
00:22:00,535 --> 00:22:04,470
The relief valves are shown here.

305
00:22:04,505 --> 00:22:08,810
And there is an O2/N2 supply panel which has
all of the valves and regulators and everything

306
00:22:08,845 --> 00:22:11,350
on it.

307
00:22:11,385 --> 00:22:18,350
This system, however, though, gets most of
its oxygen from the cryogenic tanks.

308
00:22:19,650 --> 00:22:21,750
So that is only just shown as an inlet.

309
00:22:21,785 --> 00:22:25,830
These tanks are basically part of the power
control system.

310
00:22:25,865 --> 00:22:30,270
Electrical power is hydrogen and oxygen fuel
cell.

311
00:22:30,305 --> 00:22:34,210
We use a lot less oxygen than they do so the
storage was integrated.

312
00:22:34,245 --> 00:22:39,720
And then we use the oxygen for most of the
uses.

313
00:22:39,755 --> 00:22:44,080
It comes from the main tanks.

314
00:22:44,115 --> 00:22:44,890
This is a schematic.

315
00:22:44,925 --> 00:22:46,520
I will start right there.

316
00:22:46,555 --> 00:22:49,680
This is the cryogenic system.

317
00:22:49,715 --> 00:22:52,380
This is the main cryogenic system.

318
00:22:52,415 --> 00:22:58,050
This is not part of the tankage of the pressure
and composition control system.

319
00:22:58,085 --> 00:22:58,950
It goes through a restrictor.

320
00:22:58,985 --> 00:23:05,840
This is stored in a super critical state so
the delivery is somewhat limited.

321
00:23:05,875 --> 00:23:09,840
And so this goes through a restrictor so that
we don't decrease the pressure too fast in

322
00:23:09,875 --> 00:23:10,630
the cryogenic tank.

323
00:23:10,665 --> 00:23:17,190
It comes on down through a regulator that
regulates down to 100 PSI.

324
00:23:17,225 --> 00:23:20,800
And that comes on down to two regulators.

325
00:23:20,835 --> 00:23:26,210
One is the normal regulator, the 14.7, and
the other is the 8 PSI regulator, both of

326
00:23:26,245 --> 00:23:31,480
which are available depending on which cabin
mode you're in.

327
00:23:31,515 --> 00:23:34,220
If you go over this way you will see the nitrogen.

328
00:23:34,255 --> 00:23:39,840
The nitrogen goes through its own regulator,
and it is regulated at 200 PSI.

329
00:23:39,875 --> 00:23:42,460
And that's important because that is contrasted
to the 100 here.

330
00:23:42,495 --> 00:23:49,460
Next the nitrogen goes through an on/off valve,
a solenoid that is connected to partial pressure

331
00:23:49,540 --> 00:23:51,060
sensors of oxygen.

332
00:23:51,095 --> 00:23:58,060
And, if you're making up cabin gas, you have
to make a choice as to whether you want nitrogen

333
00:23:58,690 --> 00:23:59,890
or oxygen.

334
00:23:59,925 --> 00:24:04,500
And that choice is made by this system and
a simple on/off valve.

335
00:24:04,535 --> 00:24:06,540
There is no sophisticated control system.

336
00:24:06,575 --> 00:24:08,490
This is a simple on/off valve.

337
00:24:08,525 --> 00:24:14,440
If the cabin needs pressure but doesn't need
oxygen then this valve is open and the 200

338
00:24:14,475 --> 00:24:17,990
PSI basically backs down the oxygen system.

339
00:24:18,025 --> 00:24:21,950
There is a check valve here, no oxygen flow
because you get nitrogen.

340
00:24:21,985 --> 00:24:27,680
At the point that you need oxygen, this valve
closes, then there is no 200 PSI anymore.

341
00:24:27,715 --> 00:24:30,830
Therefore, the 100 PSI provides oxygen to
the regulators.

342
00:24:30,865 --> 00:24:32,500
It is a very simple design.

343
00:24:32,535 --> 00:24:38,730
Off the top of your head, what kind of failures
did you have during qual test that really

344
00:24:38,765 --> 00:24:39,480
bothered you?

345
00:24:39,515 --> 00:24:46,480
The regulators were produced by Carlton, and
the regulators were derivatives of regulators

346
00:24:50,210 --> 00:24:51,250
they had been building for years.

347
00:24:51,285 --> 00:24:53,500
So the regulator functions really were pretty
good.

348
00:24:53,535 --> 00:25:00,500
But the early problem we had was the pressure
tolerance wandered and didn't have as good

349
00:25:01,230 --> 00:25:02,020
a pressure tolerance.

350
00:25:02,055 --> 00:25:04,450
And they did make some mods to correct that.

351
00:25:04,485 --> 00:25:08,980
But the more significant issues got into flow
issues.

352
00:25:09,015 --> 00:25:10,820
Their test capability was pretty limited.

353
00:25:10,855 --> 00:25:17,330
And when you're talking about very high flow
cases you have to do something with the gas

354
00:25:17,365 --> 00:25:21,420
to make the regulator think that it is in
an operational environment.

355
00:25:21,455 --> 00:25:27,130
And so we did a lot of testing, and I will
show you that in just a second, for the high

356
00:25:27,165 --> 00:25:27,510
flow cases.

357
00:25:27,545 --> 00:25:32,600
Let's see.

358
00:25:32,635 --> 00:25:33,490
There is a redundant system.

359
00:25:33,525 --> 00:25:37,360
It is not shown in this schematic but there
are two of these, just like this.

360
00:25:37,395 --> 00:25:40,610
This is the pressurization for the water and
waste management system you see here.

361
00:25:40,645 --> 00:25:47,610
I would say there is a crossover to the redundant
system so that you can do mix and match.

362
00:25:48,440 --> 00:25:54,700
If you have a problem in both systems, you
can mix and match the capabilities.

363
00:25:54,735 --> 00:25:59,600
Also, the oxygen system provides the emergency
breathing system.

364
00:25:59,635 --> 00:26:04,380
It also provides oxygen to the air lock for
recharge of the backpack.

365
00:26:04,415 --> 00:26:05,190
We will talk about that later.

366
00:26:05,225 --> 00:26:09,010
And I believe that's it.

367
00:26:09,045 --> 00:26:11,320
So, for normal pressure, we have 14.7.

368
00:26:11,355 --> 00:26:17,750
And you have the automatic pressure regulator,
basically on/off valve and the regulator.

369
00:26:17,785 --> 00:26:24,750
The partial pressure is controlled by the
3.2 PSI which is the solenoid that controls

370
00:26:25,450 --> 00:26:25,700
that.

371
00:26:25,640 --> 00:26:29,080
It is a very simple system.

372
00:26:29,115 --> 00:26:36,080
The oxygen partial pressure does have another
set point at the PSIA goes down to 2.45 PSI.

373
00:26:36,380 --> 00:26:38,510
And I will show you that in a minute.

374
00:26:38,545 --> 00:26:44,270
For cabin pressure relief, the problem statement
really is why do you need relief?

375
00:26:44,305 --> 00:26:46,600
Well, what if one of those lines breaks?

376
00:26:46,635 --> 00:26:48,770
You've got 3300 PSI tankage.

377
00:26:48,805 --> 00:26:52,480
It is all plumed together.

378
00:26:52,515 --> 00:26:57,900
The crew, God forbid, step on a line and break
it, and now you've got all this nitrogen rushing

379
00:26:57,935 --> 00:26:58,390
in.

380
00:26:58,425 --> 00:27:00,600
You don't want the cabin to explode, right?

381
00:27:00,635 --> 00:27:03,520
So you need a relief valve.

382
00:27:03,555 --> 00:27:05,630
And the relief valve was set at 16.2.

383
00:27:05,665 --> 00:27:11,810
And, again, that is one of the high flow cases
that we ended up testing.

384
00:27:11,845 --> 00:27:14,070
The system was designed with three relief
valves.

385
00:27:14,105 --> 00:27:15,340
Any tool will do the job.

386
00:27:15,375 --> 00:27:17,930
That is just a redundancy philosophy.

387
00:27:17,965 --> 00:27:23,220
Sometimes you will see two items where either
one does the job.

388
00:27:23,255 --> 00:27:28,300
In this case, this is a very critical issue
so there is a double redundancy here.

389
00:27:28,335 --> 00:27:34,970
For the negative pressure protection, there
is an 8 PSI delta relief valve.

390
00:27:35,005 --> 00:27:36,710
In fact, there are three of those.

391
00:27:36,745 --> 00:27:40,380
You don't need the two to operate, but there
are three.

392
00:27:40,415 --> 00:27:43,600
This is for the return that I just showed
you.

393
00:27:43,635 --> 00:27:50,600
If you come back with a hole in the cabin,
the cabin is at 8 PSI, you cannot reverse

394
00:27:50,620 --> 00:27:51,380
flow through that hole.

395
00:27:51,415 --> 00:27:52,890
That is not going to work.

396
00:27:52,925 --> 00:27:56,500
You don't want the cabin imploding on the
crew so you've got to make up, as you come

397
00:27:56,535 --> 00:28:00,740
in the lower altitude, obviously the higher
pressure, you've got to get that gas back

398
00:28:00,775 --> 00:28:01,510
in the cabin.

399
00:28:01,545 --> 00:28:07,309
So that's what that is for.

400
00:28:07,344 --> 00:28:08,050
OK.

401
00:28:08,085 --> 00:28:14,300
This is the other pressure vessel that was
used as a test site.

402
00:28:14,335 --> 00:28:18,400
This was called the Environmental Test Article.

403
00:28:18,435 --> 00:28:21,490
Rockwell gave it that name.

404
00:28:21,525 --> 00:28:27,130
What they planned to do with this device,
when they built it, was to do all the wiring

405
00:28:27,165 --> 00:28:28,840
runs and the plumbing runs in there.

406
00:28:28,875 --> 00:28:30,220
It was going to be a mockup.

407
00:28:30,255 --> 00:28:33,490
It turned out they built a rather beefy tank.

408
00:28:33,525 --> 00:28:36,470
In fact, maybe they got one very inexpensively.

409
00:28:36,505 --> 00:28:39,400
I'm not sure how they ended up with it, but
they got it.

410
00:28:39,435 --> 00:28:43,340
They did do all the secondary structure, so
it had the right shape inside.

411
00:28:43,375 --> 00:28:46,740
And so it turned out they didn't end up using
it.

412
00:28:46,775 --> 00:28:50,360
They went onto other methods.

413
00:28:50,395 --> 00:28:54,150
And so it ended up leftover in the program.

414
00:28:54,185 --> 00:28:59,770
We convinced Aaron that he ought to give it
to us, and he did.

415
00:28:59,805 --> 00:29:03,240
This is what it looks like in cutaway.

416
00:29:03,275 --> 00:29:08,330
You see here all the secondary structure,
it was in boxes but we put it all in.

417
00:29:08,365 --> 00:29:12,590
Foamed it in so that the volume was right,
so the cabin volume was essentially perfect.

418
00:29:12,625 --> 00:29:14,380
It had the flight deck.

419
00:29:14,415 --> 00:29:15,150
It had the mid deck.

420
00:29:15,185 --> 00:29:17,670
It had the lower deck for the environmental
control system.

421
00:29:17,705 --> 00:29:21,430
But we also asked Aaron to give us the cert
hardware, which he did.

422
00:29:21,465 --> 00:29:25,340
So we had the cert hardware underneath the
floor.

423
00:29:25,375 --> 00:29:30,190
And the pressure control system we're talking
about, actually, is on this back wall.

424
00:29:30,225 --> 00:29:32,690
That is a picture of it.

425
00:29:32,725 --> 00:29:35,270
What we did is faithfully run the lines.

426
00:29:35,305 --> 00:29:39,710
In fact, we even use the same line material,
same fittings, same everything.

427
00:29:39,745 --> 00:29:46,710
So we faithfully duplicated inside this test
article the volume and the geometry and the

428
00:29:47,180 --> 00:29:48,290
system.

429
00:29:48,325 --> 00:29:50,720
All the ventilation ducts you saw, all those
were in place.

430
00:29:50,755 --> 00:29:57,720
We will come back to it later, but you'll
notice on the back wall of this test facility

431
00:29:59,900 --> 00:30:02,200
there is an airlock hatch.

432
00:30:02,235 --> 00:30:04,720
And later on I will tell you where that goes.

433
00:30:04,755 --> 00:30:11,720
But this is the control panel and the nitrogen/oxygen
system.

434
00:30:14,150 --> 00:30:17,210
This is test data.

435
00:30:17,245 --> 00:30:20,110
We did some testing to see how the system
worked.

436
00:30:20,145 --> 00:30:23,210
This was testing of basically the on/off oxygen
control system.

437
00:30:23,245 --> 00:30:27,100
Let me see if I can walk through this simply.

438
00:30:27,135 --> 00:30:31,340
We're working total pressure here, oxygen
partial pressure here.

439
00:30:31,375 --> 00:30:36,280
During this first interval the oxygen is on.

440
00:30:36,315 --> 00:30:38,470
What we're doing here is we're breathing it
down.

441
00:30:38,505 --> 00:30:45,470
And, when we hit the lower limit so that the
regulator wants to do something, then the

442
00:30:45,910 --> 00:30:49,350
oxygen partial pressure starts up because
the regulator comes on.

443
00:30:49,385 --> 00:30:52,350
Now, the total pressure is maintained because
that is what the regulator is supposed to

444
00:30:52,385 --> 00:30:53,630
do, maintain total pressure.

445
00:30:53,665 --> 00:30:57,370
But as it maintains the total pressure it
is doing it with oxygen and, therefore, the

446
00:30:57,405 --> 00:30:59,070
partial pressure is going up.

447
00:30:59,105 --> 00:31:06,070
When it is satisfied, that is enough partial
pressure of oxygen, then the solenoid valve

448
00:31:07,309 --> 00:31:09,530
opens and you see the nitrogen come on.

449
00:31:09,565 --> 00:31:13,650
Now, you remember the nitrogen feed was at
300 PSI versus 200 PSI.

450
00:31:13,685 --> 00:31:15,460
So there is a little jump.

451
00:31:15,495 --> 00:31:18,650
That is just a mechanical artifact of the
regulator.

452
00:31:18,685 --> 00:31:23,570
If you change the inlet pressure it regulates
slightly differently because it is a balance

453
00:31:23,605 --> 00:31:25,059
system.

454
00:31:25,094 --> 00:31:27,070
You see a little jump there.

455
00:31:27,105 --> 00:31:32,140
And then, during this period, the pressure
is maintained.

456
00:31:32,175 --> 00:31:35,790
But we're breathing off the oxygen because
we've got the oxygen fenced off now.

457
00:31:35,825 --> 00:31:40,860
And then when the pressure is satisfied and
the solenoid goes back the other way then

458
00:31:40,895 --> 00:31:43,090
we again start the oxygen again.

459
00:31:43,125 --> 00:31:44,450
So the system worked quite well.

460
00:31:44,485 --> 00:31:49,330
If you notice the tolerance band spec-wise
was pretty wide, the system operated on a

461
00:31:49,365 --> 00:31:51,010
very narrow brand so we were very pleased
with that.

462
00:31:51,045 --> 00:31:54,120
Normally that is important.

463
00:31:54,155 --> 00:31:59,659
Not only because it shows you that you do
have a good sensitive system, but you cannot

464
00:31:59,694 --> 00:32:04,309
-- Mechanical hardware, electrical hardware,
either one never operates down the middle

465
00:32:04,344 --> 00:32:05,050
always.

466
00:32:05,085 --> 00:32:06,610
There is drift.

467
00:32:06,645 --> 00:32:12,860
You need a little tolerance in your band here
to have a decent system design.

468
00:32:12,895 --> 00:32:13,110
Yes.

469
00:32:13,080 --> 00:32:18,950
Does this change a lot when you have the crew
performing high metabolic activity?

470
00:32:18,985 --> 00:32:21,650
The cabin is so large that it really doesn't
know.

471
00:32:21,685 --> 00:32:26,450
The cycles would be different, obviously,
because you consume more oxygen, you would

472
00:32:26,485 --> 00:32:27,120
need more oxygen.

473
00:32:27,155 --> 00:32:31,370
So the on/off cycle would favor longer oxygen
cycles.

474
00:32:31,405 --> 00:32:37,150
But, in the big picture, there is really not
a lot of change.

475
00:32:37,185 --> 00:32:38,640
What was this time period?

476
00:32:38,675 --> 00:32:43,510
It looks like this was about three hours maybe.

477
00:32:43,545 --> 00:32:46,730
That might go to two hours for a cycle.

478
00:32:46,765 --> 00:32:47,860
I mean not really very much.

479
00:32:47,895 --> 00:32:48,760
Sorry.

480
00:32:48,795 --> 00:32:55,000
Does microgravity have much effect on circulation?

481
00:32:55,035 --> 00:33:01,050
There is no circulation in microgravity.

482
00:33:01,085 --> 00:33:04,890
It just lays there.

483
00:33:04,925 --> 00:33:10,910
You push it or it doesn't go.

484
00:33:10,945 --> 00:33:15,690
Diffusion is a driving force, so if you're
really, really patient, even at zero G you

485
00:33:15,725 --> 00:33:20,530
can wait, but you cannot stay alive that way.

486
00:33:20,565 --> 00:33:27,530
But, yes, you do have to have ventilation.

487
00:33:29,080 --> 00:33:30,990
Still in the atmospheric pressure and composition
control.

488
00:33:31,025 --> 00:33:32,880
This is the emergency breathing equipment.

489
00:33:32,915 --> 00:33:36,710
We used plug-in face masks.

490
00:33:36,745 --> 00:33:43,710
There are some uses for the mask that require
a carry on bottle to give portability, but

491
00:33:44,570 --> 00:33:46,429
the vehicle does have plug-in capability.

492
00:33:46,464 --> 00:33:49,059
The masks were purge-type masks.

493
00:33:49,094 --> 00:33:54,780
You're probably not familiar much with masks,
but there is a mask called a rebreather which

494
00:33:54,815 --> 00:33:59,120
basically your lung power does all the work
and you only purge enough to keep the CO2

495
00:33:59,155 --> 00:34:00,920
down and you keep rebreathing.

496
00:34:00,955 --> 00:34:07,090
And then the purge-type is every breath is
a fresh breath, and you then exhale and the

497
00:34:07,125 --> 00:34:08,740
gas goes out in the cabin.

498
00:34:08,775 --> 00:34:12,109
And that's the type that this is because the
cabin needs the oxygen.

499
00:34:12,144 --> 00:34:13,280
I mean it's not going anywhere bad.

500
00:34:13,315 --> 00:34:15,389
It is OK that it's not completely spent.

501
00:34:15,424 --> 00:34:16,530
It's good.

502
00:34:16,565 --> 00:34:22,269
That's like a scuba mask, right?

503
00:34:22,304 --> 00:34:23,879
I don't scuba.

504
00:34:23,914 --> 00:34:24,179
Sorry.

505
00:34:24,214 --> 00:34:28,139
But I think the answer is yes.

506
00:34:28,174 --> 00:34:30,730
With scuba, you take in the air and then you
blow it all out.

507
00:34:30,765 --> 00:34:37,579
I mean there are scuba rebreathing systems,
but the typical scuba gear is not.

508
00:34:37,614 --> 00:34:42,339
Rather than raising your hand, if you make
a noise of some kind.

509
00:34:42,374 --> 00:34:42,919
Sorry.

510
00:34:42,954 --> 00:34:46,869
I don't mean to ignore you.

511
00:34:46,904 --> 00:34:52,539
The mask can be used in a contaminated environment
and the mask can be used if the concentration

512
00:34:52,574 --> 00:34:58,999
of O2 is low to give you a better oxygen level.

513
00:34:59,034 --> 00:35:03,160
This is the PSIA test that we did.

514
00:35:03,195 --> 00:35:03,940
Actually, a series of tests.

515
00:35:03,975 --> 00:35:05,549
But this is data from one.

516
00:35:05,584 --> 00:35:08,880
As you see, we started up in the 14.7 range.

517
00:35:08,915 --> 00:35:10,239
We simulated the hole.

518
00:35:10,274 --> 00:35:13,150
The pressure immediately starts down.

519
00:35:13,185 --> 00:35:20,150
The partial pressure of oxygen we let degrade
to about the 2.2 range.

520
00:35:22,849 --> 00:35:24,779
This is a different set point.

521
00:35:24,814 --> 00:35:27,130
Remember I told you on the oxygen sensors
we have two set points?

522
00:35:27,165 --> 00:35:28,539
This is the second set point.

523
00:35:28,574 --> 00:35:32,039
And so we have the lower oxygen partial pressure.

524
00:35:32,074 --> 00:35:33,339
The system came down.

525
00:35:33,374 --> 00:35:40,339
The PSIA regulator, which is always online,
captured the pressure decay, caught it, and

526
00:35:40,589 --> 00:35:45,099
the solenoid valve popped back and forth to
keep the oxygen OK because we're losing now.

527
00:35:45,134 --> 00:35:47,019
We're going out this half-inch hole.

528
00:35:47,054 --> 00:35:48,789
And the system worked just fine.

529
00:35:48,824 --> 00:35:53,900
This did have the crew on the masks because
that is livable, you can live there, but the

530
00:35:53,935 --> 00:35:54,900
mask is a better environment.

531
00:35:54,935 --> 00:36:01,559
This is a mask case.

532
00:36:01,594 --> 00:36:03,809
This was a requirement that came on later.

533
00:36:03,844 --> 00:36:05,059
The design is the design now.

534
00:36:05,094 --> 00:36:12,059
The vehicle exists so we have to now operate
the vehicle with accommodations for operationally

535
00:36:13,470 --> 00:36:15,489
what we want to do with it.

536
00:36:15,524 --> 00:36:20,630
And a new requirement developed and was imposed
on the vehicle.

537
00:36:20,665 --> 00:36:25,059
And that requirement had to do with the space
suit for the EVA operation.

538
00:36:25,094 --> 00:36:28,880
The Shuttle spacesuits are basically 100%
O2.

539
00:36:28,915 --> 00:36:33,900
And the classical way of going EVA from a
sea level environment was a four hour prebreathe.

540
00:36:33,935 --> 00:36:40,900
Actually, as much as six hours depending on
how conservative the medics were at the time,

541
00:36:44,569 --> 00:36:50,230
that number varied around some, to prevent
bends.

542
00:36:50,265 --> 00:36:56,210
But it was determined that if you accommodized
at 9 PSI for about 12 hours then you only

543
00:36:56,245 --> 00:36:58,249
required a really short prebreathe.

544
00:36:58,284 --> 00:37:04,809
And the suit-up time, which gave you 30 to
40 minutes, actually gave you sort of a free

545
00:37:04,844 --> 00:37:09,200
tune-up to your prebreathe as part of your
suit-up operation.

546
00:37:09,235 --> 00:37:14,950
And so that was viewed as a much better way
to do EVAs than the previous way.

547
00:37:14,985 --> 00:37:19,720
The masks are useful but are not very comfortable.

548
00:37:19,755 --> 00:37:22,660
So, if you have to keep them on for a long
period of time, they're not very comfortable

549
00:37:22,695 --> 00:37:24,059
at all.

550
00:37:24,094 --> 00:37:29,589
Also the medics were very concerned about
mask leakage, that if there was any nitrogen

551
00:37:29,624 --> 00:37:33,249
inflow that that could break the prebreathe.

552
00:37:33,284 --> 00:37:35,190
But our system isn't designed for 9.

553
00:37:35,225 --> 00:37:41,529
We have a 14.7 and an eight, but we don't
have a 9, so we needed a manual procedure.

554
00:37:41,564 --> 00:37:45,259
But before that could be accepted there were
some issues that had to be evaluated.

555
00:37:45,294 --> 00:37:50,099
And we had to do testing on each of these
issues.

556
00:37:50,134 --> 00:37:52,829
The first is the flow rate acceptability at
9 PSI.

557
00:37:52,864 --> 00:37:57,650
Obviously, the less dense gas you're not going
to get the same mask flow rate.

558
00:37:57,685 --> 00:38:01,910
And we had to make sure that that ventilation
was going to be adequate.

559
00:38:01,945 --> 00:38:06,279
And testing proved that it was.

560
00:38:06,314 --> 00:38:07,690
The next is a thermal acceptability.

561
00:38:07,725 --> 00:38:09,440
There are really two aspects to this.

562
00:38:09,475 --> 00:38:15,119
One is the fan itself is cooled by the environment,
so if the environment doesn't provide as much

563
00:38:15,154 --> 00:38:17,430
cooling to fan itself it could overheat.

564
00:38:17,465 --> 00:38:24,430
Also, the electronic equipment, some of which
is air cooled, the less dense gas could be

565
00:38:25,039 --> 00:38:26,309
a problem there.

566
00:38:26,344 --> 00:38:28,809
It turned out that could be controlled with
load control.

567
00:38:28,844 --> 00:38:33,559
That could off load power and make that acceptable.

568
00:38:33,594 --> 00:38:38,549
The CO2 performance at 9 PSI, we needed to
make sure that was OK.

569
00:38:38,584 --> 00:38:42,440
It turned out that, of course, the 9 PSI case,
we don't care about the lithium hydroxide.

570
00:38:42,475 --> 00:38:45,190
The purge flow is so great there is no CO2
problem.

571
00:38:45,225 --> 00:38:50,150
But at 9 PSI for 12 hours you have to get
performance out of the lithium hydroxide.

572
00:38:50,185 --> 00:38:52,059
So we checked that and that worked out fine.

573
00:38:52,094 --> 00:38:55,569
And the last item was the ventilation adequacy.

574
00:38:55,604 --> 00:38:57,170
We do have a press and depress.

575
00:38:57,205 --> 00:38:59,069
You've got to come down to 9 and you've got
to go back.

576
00:38:59,104 --> 00:39:01,799
And both of those adjust the gas mixture.

577
00:39:01,834 --> 00:39:05,619
And so we wanted to prove that that was OK.

578
00:39:05,654 --> 00:39:10,829
And so we went to the facility that we were
talking about and ran this profile.

579
00:39:10,864 --> 00:39:17,299
Now, this profile was created by our-- yes?

580
00:39:17,334 --> 00:39:24,299
[AUDIENCE QUESTION]

581
00:39:25,769 --> 00:39:27,119
Well, that's what I just said.

582
00:39:27,154 --> 00:39:27,890
Yes, it does.

583
00:39:27,925 --> 00:39:33,069
The air-cooled equipment is going to run hot.

584
00:39:33,104 --> 00:39:39,309
If you want to cool that equipment, it will
become a little clearer later, but the equipment

585
00:39:39,344 --> 00:39:41,200
is in equipment bays.

586
00:39:41,235 --> 00:39:46,299
And so, with the less dense gas, you need
to have some of that equipment turned off

587
00:39:46,334 --> 00:39:49,249
so that the cooling that is available is adequate.

588
00:39:49,284 --> 00:39:52,539
So you do load control, get rid of some of
the electronics.

589
00:39:52,574 --> 00:39:59,539
And, therefore, the air that's left, the atmosphere
that is left can cool the equipment.

590
00:40:01,839 --> 00:40:02,700
And then when do you increase the pressure
back to normal after the EVA?

591
00:40:02,735 --> 00:40:03,150
After the 12 hours.

592
00:40:03,185 --> 00:40:07,769
No, actually it's before the EVA.

593
00:40:07,804 --> 00:40:10,039
Well, I'm not sure what they do now.

594
00:40:10,074 --> 00:40:14,039
When you're all finished with your EVAs then
you bring the cabin back.

595
00:40:14,074 --> 00:40:17,680
Because, typically, you do multiple EVAs.

596
00:40:17,715 --> 00:40:23,130
And so, from one day to the next, you just
keep the cabin at, actually, we use 10.2 now

597
00:40:23,165 --> 00:40:28,819
rather than 9, but I think you have to certify
it for 9, right?

598
00:40:28,854 --> 00:40:31,180
This was an early certification for 9.

599
00:40:31,215 --> 00:40:31,720
Yes.

600
00:40:31,755 --> 00:40:38,700
But wouldn't it have been easier to simply
design the whole system for 9 from the beginning

601
00:40:38,735 --> 00:40:43,279
if you had [OVERLAPPING VOICES]?

602
00:40:43,314 --> 00:40:44,710
Well, this was not a Shuttle requirement.

603
00:40:44,745 --> 00:40:50,440
This was an operational requirement that occurred
after the Shuttle specifications were set.

604
00:40:50,475 --> 00:40:52,160
You're correct.

605
00:40:52,195 --> 00:40:57,410
If we knew it ahead of time it would have
been much easier to do it all for 9 PSIs,

606
00:40:57,445 --> 00:40:59,079
exactly.

607
00:40:59,114 --> 00:41:01,369
It would have just been a third condition.

608
00:41:01,404 --> 00:41:04,470
But, as Jeff pointed out, we changed our mind.

609
00:41:04,505 --> 00:41:09,989
The first was 9 and now we're at 10.2, so
we're not consistent.

610
00:41:10,024 --> 00:41:12,069
As we learn, we change our mind.

611
00:41:12,104 --> 00:41:17,229
And the 10.2 was selected later.

612
00:41:17,264 --> 00:41:22,829
Our mission operations people that do the
crew time lining and all, they created this

613
00:41:22,864 --> 00:41:23,079
procedure.

614
00:41:22,829 --> 00:41:24,130
And so we tested it.

615
00:41:24,165 --> 00:41:26,339
This has a simple depress cycle.

616
00:41:26,374 --> 00:41:27,640
You come from 14.7.

617
00:41:27,675 --> 00:41:32,220
You hesitate at about 11 and replenish the
oxygen.

618
00:41:32,255 --> 00:41:34,029
You do that twice.

619
00:41:34,064 --> 00:41:39,559
You then do manual control down at the 9 psi
level.

620
00:41:39,594 --> 00:41:46,559
You notice the oxygen partial pressure here
is always maintained by these adjustments,

621
00:41:49,749 --> 00:41:53,269
and also during the manual period you select
what you want.

622
00:41:53,304 --> 00:41:58,430
And then when you come back, the procedure
was to increase the nitrogen and then finish

623
00:41:58,465 --> 00:42:00,190
the top off with oxygen.

624
00:42:00,225 --> 00:42:07,190
That was thought to be completely acceptable
because the oxygen level, at this point, is

625
00:42:07,225 --> 00:42:07,869
completely viable.

626
00:42:07,904 --> 00:42:14,239
And so doing the nitrogen first and topping
it off with oxygen was thought to be an acceptable

627
00:42:14,274 --> 00:42:16,319
way to operate.

628
00:42:16,354 --> 00:42:22,690
So we did the test and this is what happened.

629
00:42:22,725 --> 00:42:26,329
We were all nice and comfortable with our
oxygen partial pressure.

630
00:42:26,364 --> 00:42:32,170
And you see the area next to where we were
repressing.

631
00:42:32,205 --> 00:42:35,729
We depleted the oxygen substantially.

632
00:42:35,764 --> 00:42:40,559
And the mid deck and even the flight deck,
we depleted the oxygen.

633
00:42:40,594 --> 00:42:43,150
And I've only shown you half the data.

634
00:42:43,185 --> 00:42:47,720
If you look at the rest of the data, you see
where the oxygen went.

635
00:42:47,755 --> 00:42:52,479
These equipment bays that I mentioned earlier,
the avionics bays and other equipment bays

636
00:42:52,514 --> 00:42:58,089
are basically isolated volumes from the cabin.

637
00:42:58,124 --> 00:43:04,029
So, as the pressure comes up, what you're
doing is you're pressurizing these areas with

638
00:43:04,064 --> 00:43:11,029
cabin gas, which is oxygen and nitrogen, you're
pressurizing these areas with nitrogen only.

639
00:43:11,369 --> 00:43:14,700
Basically, you are depleting the partial pressure
here.

640
00:43:14,735 --> 00:43:16,999
You're increasing the partial pressure here.

641
00:43:17,034 --> 00:43:17,940
You remember partial pressure.

642
00:43:17,975 --> 00:43:19,009
You just count the molecules.

643
00:43:19,044 --> 00:43:21,019
That's all you have to do.

644
00:43:21,054 --> 00:43:27,059
Basically, we're putting more oxygen molecules
here and we're taking them out of these areas.

645
00:43:27,094 --> 00:43:30,970
And, therefore, they are going down.

646
00:43:31,005 --> 00:43:33,109
This is just a picture of one of the bays.

647
00:43:33,144 --> 00:43:35,269
You see all the empty space around the equipment.

648
00:43:35,304 --> 00:43:38,690
That is where the gas is.

649
00:43:38,725 --> 00:43:43,440
We came up with an alternate procedure which
is to simultaneously put the oxygen and nitrogen

650
00:43:43,475 --> 00:43:45,039
in together.

651
00:43:45,074 --> 00:43:49,049
And, of course, there is the 9 back to 14.7.

652
00:43:49,084 --> 00:43:50,589
And you notice that solved the problem.

653
00:43:50,624 --> 00:43:56,999
There is still some dip at the supply area
because the mixture is lean.

654
00:43:57,034 --> 00:44:02,970
We need from 9 to 14.7, 5.7 PSI total pressure
increase.

655
00:44:03,005 --> 00:44:08,279
But we only need 2.5 up to 3.2 oxygen.

656
00:44:08,314 --> 00:44:11,589
This is a mixture, but it's a lean mixture.

657
00:44:11,624 --> 00:44:18,029
So there is still some slight loss, but the
only area that came under an issue is near

658
00:44:18,064 --> 00:44:21,630
the inlet where the O2/N2 supply panel is.

659
00:44:21,665 --> 00:44:23,640
And, of course, you can just avoid that area.

660
00:44:23,675 --> 00:44:28,599
Well, I should say that that area happens
to be right around the bathroom.

661
00:44:28,634 --> 00:44:34,499
And so, before we repressurized the Shuttle,
the commander would say anybody who has to

662
00:44:34,534 --> 00:44:41,369
use the bathroom use it now because for about
ten, fifteen minutes, while we're depressurizing,

663
00:44:41,404 --> 00:44:44,640
it's off limits.

664
00:44:44,675 --> 00:44:44,950
OK.

665
00:44:44,985 --> 00:44:46,789
Next item.

666
00:44:46,824 --> 00:44:52,509
This is the water and waste management area.

667
00:44:52,544 --> 00:44:55,739
This is one of the six items.

668
00:44:55,774 --> 00:44:59,119
We have potable and waste water inventory
management.

669
00:44:59,154 --> 00:45:03,170
We're continually producing potable water,
as you know, and waste water.

670
00:45:03,205 --> 00:45:07,400
We have to dump them, we have to use them,
so that is part of the requirement of this

671
00:45:07,435 --> 00:45:07,650
system.

672
00:45:07,400 --> 00:45:14,400
We have to store water for drinking, food
prep and waste water storage.

673
00:45:16,119 --> 00:45:19,200
It has to be dumped to space.

674
00:45:19,235 --> 00:45:21,650
Commode and urinal for human waste collection.

675
00:45:21,685 --> 00:45:26,650
And we provide water for an evaporative heat
sink, which we will talk about later, called

676
00:45:26,685 --> 00:45:28,210
the flash evaporator.

677
00:45:28,245 --> 00:45:28,749
Yes.

678
00:45:28,784 --> 00:45:32,479
This is an outstanding example of systems
engineers, this total system that Walt is

679
00:45:32,514 --> 00:45:32,729
talking about.

680
00:45:32,479 --> 00:45:39,279
We can really see the interaction between
all the systems and the spacecraft.

681
00:45:39,314 --> 00:45:44,109
This really is a systems engineering problem.

682
00:45:44,144 --> 00:45:50,009
Potable water, we take all the fuel cell byproduct
water and use it.

683
00:45:50,044 --> 00:45:53,029
So it is basically in a fluent to the power
system.

684
00:45:53,064 --> 00:46:00,029
We do have a launch storage capability for
water and we do provide sterilization.

685
00:46:00,140 --> 00:46:02,269
The sterilization is iodine.

686
00:46:02,304 --> 00:46:08,670
We started out designing a silver ion system.

687
00:46:08,705 --> 00:46:15,130
It turned out that we had manufacturing problems
and the company ended up going out of business,

688
00:46:15,165 --> 00:46:16,450
so we reverted to iodine.

689
00:46:16,485 --> 00:46:20,029
The Lunar Module used iodine.

690
00:46:20,064 --> 00:46:25,549
Waste water, the condensate from the cabin
humidity control and urine and the urine pretreat.

691
00:46:25,584 --> 00:46:32,349
Urine has to be pretreated to bind the urea.

692
00:46:32,384 --> 00:46:33,619
If you don't, you get a lot of ammonia.

693
00:46:33,654 --> 00:46:37,150
It uses a chemical called Oxzone.

694
00:46:37,185 --> 00:46:39,999
It's an acid.

695
00:46:40,034 --> 00:46:44,829
I'm not really sure what it is.

696
00:46:44,864 --> 00:46:46,729
This is where the system is located.

697
00:46:46,764 --> 00:46:50,680
This is one of the simpler schematics.

698
00:46:50,715 --> 00:46:53,519
The water tanks are here.

699
00:46:53,554 --> 00:46:55,019
The water comes from the fuel cell.

700
00:46:55,054 --> 00:47:02,019
As I said, by the way, the delivery is about
150 degrees and 60 psi.

701
00:47:08,880 --> 00:47:11,869
So there is a lot of hydrogen dissolved in
the water.

702
00:47:11,904 --> 00:47:16,989
The water is collected in the fuel cells on
the hydrogen side, so there is a lot of hydrogen.

703
00:47:17,024 --> 00:47:19,839
There is a hydrogen separator here.

704
00:47:19,874 --> 00:47:22,890
Otherwise, your tanks would end up full of
hydrogen which is what you don't want.

705
00:47:22,925 --> 00:47:24,460
You will get water in the tanks.

706
00:47:24,495 --> 00:47:29,220
The hydrogen separator is a silver palladium
metal.

707
00:47:29,255 --> 00:47:30,839
It is catalyzed.

708
00:47:30,874 --> 00:47:34,200
It is basically porous to hydrogen but not
to water.

709
00:47:34,235 --> 00:47:38,410
If you expose the backside to the vacuum it
pulls the hydrogen off and the water goes

710
00:47:38,445 --> 00:47:38,960
through just fine.

711
00:47:38,995 --> 00:47:45,960
I will say that there still is a rather high
gas content in the water that you drink.

712
00:47:48,859 --> 00:47:53,719
And that gas, of course, evolves once it gets
inside your stomach with predictable results.

713
00:47:53,754 --> 00:47:55,049
[LAUGHTER]

714
00:47:55,084 --> 00:47:55,299
Yes.

715
00:47:55,210 --> 00:47:59,920
In fact, all sorts of systems that Jeff could
explain.

716
00:47:59,955 --> 00:48:04,700
They have slinger systems and all sorts of
systems to get separation because it is not

717
00:48:04,735 --> 00:48:10,489
really possible to get all the gas out of
the water.

718
00:48:10,524 --> 00:48:11,829
OK.

719
00:48:11,864 --> 00:48:13,239
There is a dump system.

720
00:48:13,274 --> 00:48:16,569
There is a potable waste dump to vacuum.

721
00:48:16,604 --> 00:48:22,119
There is also a vacuum vent, which I will
show you what that is all about.

722
00:48:22,154 --> 00:48:25,710
And then the flash evaporator that I mentioned,
and I will mention more later, is in the back

723
00:48:25,745 --> 00:48:32,079
of the vehicle and it has a redundant water
feed system both sides.

724
00:48:32,114 --> 00:48:33,319
This is a schematic.

725
00:48:33,354 --> 00:48:34,700
Start at the same place.

726
00:48:34,735 --> 00:48:39,529
Water from the fuel cells goes through the
hydrogen separator and then into this bank

727
00:48:39,564 --> 00:48:40,910
of tanks.

728
00:48:40,945 --> 00:48:41,989
The tanks are pressurized.

729
00:48:42,024 --> 00:48:45,119
They are yellow bellows tanks.

730
00:48:45,154 --> 00:48:47,190
On the back side of the bellows is nitrogen.

731
00:48:47,225 --> 00:48:52,219
On the forward side, of course, is the potable
water.

732
00:48:52,254 --> 00:48:56,440
There is a hydrophobic filter on the downside
of each tank.

733
00:48:56,475 --> 00:49:02,029
If a bellows were to leak, you don't want
water into your nitrogen system.

734
00:49:02,064 --> 00:49:05,109
So this is a filter to prevent that.

735
00:49:05,144 --> 00:49:07,869
I mentioned the twin flash evaporator feeds.

736
00:49:07,904 --> 00:49:09,229
There they are.

737
00:49:09,264 --> 00:49:11,960
This is the dump nozzle here.

738
00:49:11,995 --> 00:49:16,839
The potable water system provides water to
the crew so there is a regular water interface

739
00:49:16,874 --> 00:49:18,339
and a chilled water interface here.

740
00:49:18,374 --> 00:49:21,450
I believe that is it.

741
00:49:21,485 --> 00:49:28,450
I remember there were more problems with Apollo
than there were with Shuttle.

742
00:49:32,539 --> 00:49:35,630
49:30 I don't have those sorted mentally.

743
00:49:35,665 --> 00:49:36,319
I'm sorry.

744
00:49:36,354 --> 00:49:36,890
I don't remember.

745
00:49:36,925 --> 00:49:40,819
I'm not sure.

746
00:49:40,854 --> 00:49:47,819
[AUDIENCE QUESTION]

747
00:49:48,190 --> 00:49:48,900
Maybe that was on Apollo.

748
00:49:48,935 --> 00:49:55,420
[AUDIENCE QUESTION]

749
00:49:55,455 --> 00:50:00,380
Basically that means you put your water into
a plastic bag.

750
00:50:00,415 --> 00:50:04,749
And now you can actually swing it around like
so.

751
00:50:04,784 --> 00:50:09,339
And so the water will go to the outside and
the gas is in the inside.

752
00:50:09,374 --> 00:50:16,339
So that actually separates them and you can
squeeze the gas out through a valve.

753
00:50:18,549 --> 00:50:24,269
On-orbit trash storage, there is an overboard
bleed for odor control.

754
00:50:24,304 --> 00:50:26,950
It's a very small overboard bleed to vacuum.

755
00:50:26,985 --> 00:50:33,950
And the human solid waste collection and storage
is also vacuum dried and stabilized.

756
00:50:34,700 --> 00:50:36,979
This is a waste management picture.

757
00:50:37,014 --> 00:50:38,979
The subject we were just talking about is
the vacuum vent.

758
00:50:39,014 --> 00:50:44,180
That vacuum vent does vent the commode area
where the feces are.

759
00:50:44,215 --> 00:50:48,069
That vent also provides a vent for the water
separator.

760
00:50:48,104 --> 00:50:53,749
It also provides a vent for airlock depress
for EVA.

761
00:50:53,784 --> 00:50:56,039
So this is the vacuum system.

762
00:50:56,074 --> 00:51:01,049
The urine is collected and trained in a liquid.

763
00:51:01,084 --> 00:51:05,569
Well, let me say that different.

764
00:51:05,604 --> 00:51:12,569
The urine, after it has been separated from
the gas stream, is stored in a waste tank,

765
00:51:12,700 --> 00:51:19,700
as is the humidity from the cabin atmospheric
revitalization system.

766
00:51:21,259 --> 00:51:28,259
And then that is pressurized from the pressured
composition control system and is dumped overboard.

767
00:51:30,559 --> 00:51:31,960
This waster is not used for anything.

768
00:51:31,995 --> 00:51:37,890
It is basically dumped just to do inventory
management.

769
00:51:37,925 --> 00:51:44,180
The next picture explains a little better
about the commode and the urinals themselves.

770
00:51:44,215 --> 00:51:50,319
The urinal originally had a unisex interface
cup.

771
00:51:50,354 --> 00:51:57,319
It turned out that didn't work very well,
and so later flights there was a custom male/female.

772
00:51:58,499 --> 00:52:05,499
And later there were even some more customizing
for the crew, I believe, but I don't have

773
00:52:05,519 --> 00:52:06,940
the details on that.

774
00:52:06,975 --> 00:52:13,940
The urinal itself, obviously for urination,
there needs to be some way to make the urine

775
00:52:14,289 --> 00:52:15,729
go where you want it to go.

776
00:52:15,764 --> 00:52:19,769
And those were done in fan separators.

777
00:52:19,804 --> 00:52:23,559
So there is gas pulled in the cup.

778
00:52:23,594 --> 00:52:29,400
And in training the urine, the urine then
comes down and goes through the separators.

779
00:52:29,435 --> 00:52:32,799
This is also a centrifugal-type separator.

780
00:52:32,834 --> 00:52:35,190
And then that is sent to the head that is
created here.

781
00:52:35,225 --> 00:52:42,190
Then puts that waste water urine in the waste
system.

782
00:52:43,789 --> 00:52:50,789
The EMU spacesuit, it also has a condensate
drain after each EVA, and it also goes through

783
00:52:52,819 --> 00:52:55,670
this same system and into the waste tank.

784
00:52:55,705 --> 00:52:57,259
The commode.

785
00:52:57,294 --> 00:53:00,910
Basically there is a seat.

786
00:53:00,945 --> 00:53:06,269
The seat has a small opening.

787
00:53:06,304 --> 00:53:13,269
The commode itself is basically a cylinder
or a tub.

788
00:53:13,680 --> 00:53:15,229
And there is a slinger in the bottom.

789
00:53:15,264 --> 00:53:19,710
So the slinger basically distributes the paper
and the fecal matter on the outside wall in

790
00:53:19,745 --> 00:53:21,269
a thin layer.

791
00:53:21,304 --> 00:53:28,269
The vacuum then can dry that so that it deactivates
it so it does not end up either any odor or

792
00:53:30,979 --> 00:53:35,779
creating any kind of bacteriological issues.

793
00:53:35,814 --> 00:53:41,400
But the entrainment of the fecal material
so that it, in fact, hits the slinger, is

794
00:53:41,435 --> 00:53:42,400
done with an air flow.

795
00:53:42,435 --> 00:53:46,259
The air flow comes in around the seat itself.

796
00:53:46,294 --> 00:53:49,430
That requires good contact with the seat.

797
00:53:49,465 --> 00:53:52,059
It also requires positioning.

798
00:53:52,094 --> 00:53:59,059
Positioning turned out to be an early issue,
or reliable positioning, and so a trainer

799
00:54:01,549 --> 00:54:07,769
was put together that had a camera here.

800
00:54:07,804 --> 00:54:14,769
And the trainer, I might add, was discretely
located in a non-observable place so that

801
00:54:17,460 --> 00:54:23,059
it could be used in privacy, the comings and
goings, and also the use of the facility itself.

802
00:54:23,094 --> 00:54:29,079
And they told us it was not hooked up to a
tape recorder.

803
00:54:29,114 --> 00:54:29,509
[LAUGHTER]

804
00:54:29,544 --> 00:54:33,519
Just to elaborate on that.

805
00:54:33,554 --> 00:54:37,789
Basically, the problem is it really is a rather
small opening.

806
00:54:37,824 --> 00:54:42,779
And it just doesn't feel natural to know where
to put yourself down.

807
00:54:42,814 --> 00:54:47,069
And it actually did lead to significant messes
on orbit.

808
00:54:47,104 --> 00:54:48,119
I won't go into any more detail.

809
00:54:48,154 --> 00:54:55,119
But the idea is that you would position yourself
the way you thought it should be, and then

810
00:54:55,469 --> 00:54:57,890
you would turn on the lights.

811
00:54:57,925 --> 00:54:58,569
And there is a TV screen in front of you.

812
00:54:58,604 --> 00:55:01,880
I'm not making this up.

813
00:55:01,915 --> 00:55:02,549
[LAUGHTER]

814
00:55:02,584 --> 00:55:08,519
So that you could see how close you are to
the bull's-eye.

815
00:55:08,554 --> 00:55:13,869
Enough said.

816
00:55:13,904 --> 00:55:16,769
The cabin thermal control is another one of
the subsystem elements.

817
00:55:16,804 --> 00:55:20,749
It is a circulating liquid cooling system.

818
00:55:20,784 --> 00:55:23,650
It provides the heat sink for the atmosphere
itself.

819
00:55:23,685 --> 00:55:29,359
It also provides the ability to reject that
heat to the spacecraft cooling system because

820
00:55:29,394 --> 00:55:31,519
you've got to get rid of it out of the cabin.

821
00:55:31,554 --> 00:55:36,650
It has some avionics cold plates, some air
cool avionics, support the crew in the airlock

822
00:55:36,685 --> 00:55:40,329
and a portable water chiller.

823
00:55:40,364 --> 00:55:43,259
This is the location.

824
00:55:43,294 --> 00:55:50,259
You will notice the avionics bays are listed
here with their little circulation systems.

825
00:55:53,440 --> 00:55:57,329
The liquid system then services each of those,
the chill or the condensing heat exchanger.

826
00:55:57,364 --> 00:56:02,160
And this is the place that the cabin system
connects to the spacecraft system, on the

827
00:56:02,195 --> 00:56:03,069
aft bulkhead right here.

828
00:56:03,104 --> 00:56:07,299
We will see the other half of this system
in a little bit.

829
00:56:07,334 --> 00:56:12,059
This is a schematic that is very complicated
looking but it is fairly simple.

830
00:56:12,094 --> 00:56:14,819
Let me show you the air piece first.

831
00:56:14,854 --> 00:56:16,809
Look at the black lines.

832
00:56:16,844 --> 00:56:17,709
Those are twin fans.

833
00:56:17,744 --> 00:56:21,989
It goes through the air-cooled avionics through
the heat exchanger to get rid of the heat.

834
00:56:22,024 --> 00:56:27,190
There are some cold plated avionics in each
bay, so you take care of the cold plated and

835
00:56:27,225 --> 00:56:30,930
the air-cooled in this bay and in this bay
and in this bay.

836
00:56:30,965 --> 00:56:37,019
Now you've got all of the electronics taken
care of.

837
00:56:37,054 --> 00:56:39,670
I should have started this up at the pump.

838
00:56:39,705 --> 00:56:40,319
Sorry about that.

839
00:56:40,354 --> 00:56:42,869
Here is the pump and we will come down.

840
00:56:42,904 --> 00:56:48,489
It also takes care of the forward and overhead
window mounts around the window for thermal

841
00:56:48,524 --> 00:56:48,950
control.

842
00:56:48,985 --> 00:56:54,959
And the hatch is just a way to keep those
thermally stabilized.

843
00:56:54,994 --> 00:56:58,890
Back in the early flights, we had something
called DFI, development flight instrumentation.

844
00:56:58,925 --> 00:57:00,910
It was a special instrumentation package.

845
00:57:00,945 --> 00:57:04,249
It was also liquid cooled.

846
00:57:04,284 --> 00:57:07,410
And then this is the heat exchanger to the
spacecraft system.

847
00:57:07,445 --> 00:57:08,700
It is a Freon system.

848
00:57:08,735 --> 00:57:10,559
This is where the main heat is rejected right
here.

849
00:57:10,594 --> 00:57:13,599
On the other side of this you've got cool
liquid.

850
00:57:13,634 --> 00:57:17,640
It turns out this is water.

851
00:57:17,675 --> 00:57:23,529
We go through the liquid cooling garment which
is the spacesuit cooling garment, the water

852
00:57:23,564 --> 00:57:28,759
chiller, go through the cabin heat exchanger
to cool the cabin and condense the water out

853
00:57:28,794 --> 00:57:29,839
and then back to the pump.

854
00:57:29,874 --> 00:57:32,219
I failed to mention the IMU.

855
00:57:32,254 --> 00:57:34,299
It has triply redundant fans.

856
00:57:34,334 --> 00:57:36,359
It pulls air through it.

857
00:57:36,394 --> 00:57:40,450
And that is also cooled by this gas stream.

858
00:57:40,485 --> 00:57:46,759
Anyway, this is the cabin thermal control
system.

859
00:57:46,794 --> 00:57:53,759
These functions, I just said each one of them
so I won't repeat them.

860
00:57:54,459 --> 00:57:57,319
Cabins circulating liquid cooling loop.

861
00:57:57,354 --> 00:58:00,819
As I mentioned, water is the coolant.

862
00:58:00,854 --> 00:58:03,700
Water is actually a very good coolant.

863
00:58:03,735 --> 00:58:09,229
And, if you have any requirements that push
you that way in your designing thermal control

864
00:58:09,264 --> 00:58:11,519
systems, you like water.

865
00:58:11,554 --> 00:58:14,239
Water is completely nontoxic so it can be
around the crew.

866
00:58:14,274 --> 00:58:16,999
Leaks don't make any difference.

867
00:58:17,034 --> 00:58:19,009
It has a very high CP.

868
00:58:19,044 --> 00:58:20,369
It's a really good fluid.

869
00:58:20,404 --> 00:58:22,369
The problem with water is freezing.

870
00:58:22,404 --> 00:58:25,519
You don't want to freeze it and you don't
want to get it so hot that it turns into steam.

871
00:58:25,554 --> 00:58:27,950
But if you can stay within the boundaries
it is a good fluid.

872
00:58:27,985 --> 00:58:29,359
And that is what this is.

873
00:58:29,394 --> 00:58:33,299
Redundant pumps, I showed you that on the
schematic.

874
00:58:33,334 --> 00:58:37,849
The liquid gas heat exchanger, I showed you
that before.

875
00:58:37,884 --> 00:58:42,690
Cold plates for electronic cooling and the
window hatch mount.

876
00:58:42,725 --> 00:58:49,039
The circulating gases that I mentioned for
the avionics, the cabin gas was used as a

877
00:58:49,074 --> 00:58:49,430
coolant.

878
00:58:49,465 --> 00:58:54,009
You saw the redundant fans and the doubly
redundant fans.

879
00:58:54,044 --> 00:59:01,009
I mentioned earlier, and someone commented
on it, that the promise early on was the Shuttle

880
00:59:01,359 --> 00:59:08,359
could be a less expensive development activity
if we used off the shelf avionics, the kind

881
00:59:10,410 --> 00:59:12,410
that aircraft use.

882
00:59:12,445 --> 00:59:14,119
And that's a good promise.

883
00:59:14,154 --> 00:59:21,119
It turned out that that's not a very good,
not as good a solution for thermal control

884
00:59:22,459 --> 00:59:23,519
as liquid cooled.

885
00:59:23,554 --> 00:59:30,519
Liquid cooled is a much more efficient way
of providing a heat sink to electrical equipment.

886
00:59:30,609 --> 00:59:35,339
When you blow the cabin gas through it then
you end up with the problems of if you change

887
00:59:35,374 --> 00:59:38,019
the pressure in the cabin, which we talked
about.

888
00:59:38,054 --> 00:59:41,299
That can effect cooling.

889
00:59:41,334 --> 00:59:43,349
Also you have to put out a lot more power.

890
00:59:43,384 --> 00:59:48,799
You have to blow a lot more gas than you do
power to move the liquid around, so it's not

891
00:59:48,834 --> 00:59:49,859
a very good thermal solution.

892
00:59:49,894 --> 00:59:55,499
And actually the promise of less expensive
avionics I don't think was actually fulfilled,

893
00:59:55,534 --> 00:59:59,569
although that's somebody else's topic and
not mine, because I think everything was pretty

894
00:59:59,604 --> 01:00:00,700
well custom.

895
01:00:00,735 --> 01:00:07,700
It did potentially complicate the thermal
control system for a good goal.

896
01:00:09,180 --> 01:00:14,619
And how well that goal was met, somebody else
will have to speak for it.

897
01:00:14,654 --> 01:00:17,819
Another one of the subsystem elements of the
spacecraft.

898
01:00:17,854 --> 01:00:21,369
Well, we usually take a two minute break when
we're about halfway through.

899
01:00:21,404 --> 01:00:21,660
Certainly.

900
01:00:21,695 --> 01:00:28,660
Why don't we take our two minutes now and
then we will pick it right back up?

901
01:00:42,849 --> 01:00:49,849
[AUDIENCE QUESTION]

902
01:00:54,259 --> 01:00:58,609
From an engineering standpoint, it is much
better to cool with liquid.

903
01:00:58,644 --> 01:01:01,599
If you use cold plates, it is much more efficient.

904
01:01:01,634 --> 01:01:06,279
You get a good reliable heat sink.

905
01:01:06,314 --> 01:01:11,190
And you can then design your thermal conduction
paths so that out of the avionics box you

906
01:01:11,225 --> 01:01:13,950
make sure the heat goes to the cold plate.

907
01:01:13,985 --> 01:01:16,950
And you use a lot less power.

908
01:01:16,985 --> 01:01:23,170
You can pump water a lot more efficiently
for the cooling capability than you pump gas.

909
01:01:23,205 --> 01:01:30,170
Is that what happens on the Shuttle now or
do you have a mixture?

910
01:01:36,789 --> 01:01:43,789
[AUDIENCE QUESTION]

911
01:01:43,959 --> 01:01:50,440
This is the air-cooled part of the loop and
here are the cold plates.

912
01:01:50,475 --> 01:01:57,170
Let's get the class back.

913
01:01:57,205 --> 01:02:00,709
Thank you very much.

914
01:02:00,744 --> 01:02:07,160
I am sorry.

915
01:02:07,195 --> 01:02:09,619
Did you see what I was pointing at here?

916
01:02:09,654 --> 01:02:10,819
Yeah, you put both.

917
01:02:10,854 --> 01:02:12,729
Yeah, and this is one bay.

918
01:02:12,764 --> 01:02:17,930
And they have both cold plates and the air-cooled
here, here and here.

919
01:02:17,965 --> 01:02:20,829
There they are.

920
01:02:20,864 --> 01:02:27,829
Of course, when you go outside the vehicle
there is no more air so all the external equipment

921
01:02:28,359 --> 01:02:30,449
is cold plated.

922
01:02:30,484 --> 01:02:31,160
Was there another question?

923
01:02:31,195 --> 01:02:38,160
What kind of design changes would you have
to make in order to go strictly to completely

924
01:02:40,299 --> 01:02:41,920
liquid cooled electronics?

925
01:02:41,955 --> 01:02:46,549
Well, if you're trying to use off-the-shelf
and it is air-cooled already, there is a cabinet

926
01:02:46,584 --> 01:02:48,289
right there full of it.

927
01:02:48,324 --> 01:02:50,969
If it is air-cooled already then you have
to stay with that concept.

928
01:02:51,004 --> 01:02:55,190
If you're custom designing then, from the
very beginning, you say I'm custom designing

929
01:02:55,225 --> 01:02:56,880
this to be liquid cooled.

930
01:02:56,915 --> 01:03:01,680
And then the internal design is such that
there are conduction pads to the base plate

931
01:03:01,715 --> 01:03:06,999
so that it can be cooled.

932
01:03:07,034 --> 01:03:07,469
OK.

933
01:03:07,504 --> 01:03:08,150
I guess previously to that all of our spacecraft
were liquid cooled.

934
01:03:08,185 --> 01:03:08,400
Apollo was, wasn't it?

935
01:03:08,435 --> 01:03:08,650
Yes.

936
01:03:08,459 --> 01:03:14,170
Because you had to be able to take those spacecraft
down the back?

937
01:03:14,205 --> 01:03:18,769
Right.

938
01:03:18,804 --> 01:03:25,180
We evacuated the cabin both in the Command
Module and the Lunar Module.

939
01:03:25,215 --> 01:03:31,089
And Gemini, too.

940
01:03:31,124 --> 01:03:35,549
This is the spacecraft active thermal control
system.

941
01:03:35,584 --> 01:03:36,989
This is the vehicle level.

942
01:03:37,024 --> 01:03:43,989
So now, even though we're still under this
ETCLSS, we are not talking the classical environmental

943
01:03:45,589 --> 01:03:46,910
control anymore.

944
01:03:46,945 --> 01:03:50,029
This is a bigger picture.

945
01:03:50,064 --> 01:03:56,329
Also the reason the word active is stuck in
here was a left over from previous programs,

946
01:03:56,364 --> 01:03:57,819
too.

947
01:03:57,854 --> 01:04:02,819
For example, on Apollo we had several heat
rejection systems.

948
01:04:02,854 --> 01:04:04,239
Not a single one.

949
01:04:04,274 --> 01:04:08,130
And we also did a lot of passive thermal control
on Apollo.

950
01:04:08,165 --> 01:04:12,380
We had a mission mode called "barbeque" which
is basically you roll the vehicle very slowly

951
01:04:12,415 --> 01:04:15,739
so you normalize the environment.

952
01:04:15,774 --> 01:04:19,650
If you leave the same side toward the sun
all the way to the moon that side gets really

953
01:04:19,685 --> 01:04:22,069
hot.

954
01:04:22,104 --> 01:04:27,039
This is the active system to get away from
heaters and/or vehicle level control.

955
01:04:27,074 --> 01:04:30,749
There is an on-orbit.

956
01:04:30,784 --> 01:04:32,509
We have a radiative heat sink.

957
01:04:32,544 --> 01:04:35,489
We also have an evaporative heat sink on orbit.

958
01:04:35,524 --> 01:04:39,839
During ascent and entry we have two heat sinks,
both of which are evaporative.

959
01:04:39,874 --> 01:04:42,949
We have a circulating liquid system.

960
01:04:42,984 --> 01:04:47,910
We take heat from the cabin, from the fuel
cells, hydraulics, all the cold plate avionics

961
01:04:47,945 --> 01:04:53,319
and electronics, and payloads, we do cooling
for payloads.

962
01:04:53,354 --> 01:05:00,319
All of these are the functions of the active
thermal control system.

963
01:05:10,640 --> 01:05:13,729
This, as you notice, is a lot busier than
some of the others have been.

964
01:05:13,764 --> 01:05:16,559
You will notice the radiators here on the
side wall.

965
01:05:16,594 --> 01:05:18,249
This is the doors.

966
01:05:18,284 --> 01:05:20,150
When closed up there are no radiators.

967
01:05:20,185 --> 01:05:23,640
When opened the underside of the payload doors
are your radiators.

968
01:05:23,675 --> 01:05:27,789
And this is on both side, obviously.

969
01:05:27,824 --> 01:05:31,940
That same heat exchanger that I showed you
before that interfaces with the cabin is right

970
01:05:31,975 --> 01:05:32,650
here.

971
01:05:32,685 --> 01:05:35,309
The cabin load is dumped there.

972
01:05:35,344 --> 01:05:40,569
Fuel cell load is dumped here.

973
01:05:40,604 --> 01:05:41,699
The fluid is a Freon 21.

974
01:05:41,734 --> 01:05:43,279
There is a Freon 21 pump package.

975
01:05:43,314 --> 01:05:47,029
The payload heat exchanger is here, I believe.

976
01:05:47,064 --> 01:05:50,469
Mid body cold plates.

977
01:05:50,504 --> 01:05:53,549
Aft cold plates.

978
01:05:53,584 --> 01:05:57,499
Each radiator side has its own flow control
system.

979
01:05:57,534 --> 01:06:01,630
The evaporative heat sinks, one is the flash
evaporator that I've shown you a couple times

980
01:06:01,665 --> 01:06:01,880
before.

981
01:06:01,809 --> 01:06:03,910
I will describe it a little better in the
minute.

982
01:06:03,945 --> 01:06:04,630
It is here.

983
01:06:04,665 --> 01:06:06,650
It uses water.

984
01:06:06,685 --> 01:06:11,859
There is an ammonia boiler here that is also
an evaporative heat sink.

985
01:06:11,894 --> 01:06:17,839
And when we're on the ground there is a GSE
connector for the GSE heat sink.

986
01:06:17,874 --> 01:06:21,440
[AUDIENCE QUESTION]

987
01:06:21,475 --> 01:06:23,209
More than you would ever know.

988
01:06:23,244 --> 01:06:30,209
In fact, this is the most complicated, integrated
thermal test ever run at JSC.

989
01:06:31,559 --> 01:06:33,630
And I will show you a picture of it in a minute.

990
01:06:33,665 --> 01:06:36,979
We actually tested all of that together.

991
01:06:37,014 --> 01:06:38,099
And it all had to work together.

992
01:06:38,134 --> 01:06:39,749
And it gets worse as we go along.

993
01:06:39,784 --> 01:06:43,349
I will show you all the integration factors
as we go along, but it changes from mission

994
01:06:43,384 --> 01:06:43,999
mode to mission mode.

995
01:06:44,034 --> 01:06:46,640
It changes within mission modes as to how
the system works.

996
01:06:46,675 --> 01:06:50,239
And I will try to describe that.

997
01:06:50,274 --> 01:06:52,989
OK, so this sort of gives you the feel now.

998
01:06:53,024 --> 01:06:58,630
Keep in mind, geometry is going to play an
effect here as to how you plum the system

999
01:06:58,665 --> 01:07:00,299
up.

1000
01:07:00,334 --> 01:07:07,299
So Freon is running through all of those lines
there to the radiators?

1001
01:07:07,640 --> 01:07:13,529
It will be a little clearer in a minute.

1002
01:07:13,564 --> 01:07:14,890
This is a schematic.

1003
01:07:14,925 --> 01:07:16,749
Let's start at the radiators.

1004
01:07:16,784 --> 01:07:18,640
On a good day, this is doing the job for you.

1005
01:07:18,675 --> 01:07:21,680
All the radiators are getting you nice cool
liquid.

1006
01:07:21,715 --> 01:07:25,529
The radiator uses a bypass system, so you
will see the bypass around the radiators.

1007
01:07:25,564 --> 01:07:32,529
It is good to remind yourselves that heat
load can be tremendously different.

1008
01:07:34,859 --> 01:07:41,859
And the high level mission phases, a lot of
electronics, a lot of crew activity, the vehicle

1009
01:07:44,009 --> 01:07:48,609
is alive and pumping out the power and, therefore,
pumping out the heat.

1010
01:07:48,644 --> 01:07:53,140
If you ever did one of those 28 day missions
we talked about, which was a spec requirement,

1011
01:07:53,175 --> 01:07:55,670
you can imagine this vehicle is almost quiescent.

1012
01:07:55,705 --> 01:07:58,130
It is doing very little.

1013
01:07:58,165 --> 01:08:00,069
You're trying to link them the mission.

1014
01:08:00,104 --> 01:08:04,390
So you're doing hopefully experiments or something
in SpaceLab.

1015
01:08:04,425 --> 01:08:06,959
You're doing something else.

1016
01:08:06,994 --> 01:08:08,569
The vehicle is not working for you very hard.

1017
01:08:08,604 --> 01:08:09,539
Just as an example, we have five computers.

1018
01:08:09,574 --> 01:08:10,569
And we use all five during ascent and entry,
the active phases for safety, but once you're

1019
01:08:10,604 --> 01:08:11,759
on orbit, when you have a long mission like
that, you actually power down all but two

1020
01:08:11,794 --> 01:08:12,039
of the computers.

1021
01:08:12,074 --> 01:08:12,420
That is just it.

1022
01:08:12,455 --> 01:08:13,549
And there are a lot of other systems which
you power down.

1023
01:08:13,584 --> 01:08:14,969
And that way you're limited in missions by
the electrical energy which is limited by

1024
01:08:15,004 --> 01:08:16,109
the amount of hydrogen and oxygen you can
carry for fuel cells.

1025
01:08:16,144 --> 01:08:23,109
So, by powering down, you extend your mission.

1026
01:08:40,670 --> 01:08:40,920
And, of course, you will also reduce the heat
load.

1027
01:08:40,670 --> 01:08:43,600
And, when you reduce the heat load, you've
got to find some way to make that same radiator

1028
01:08:43,635 --> 01:08:46,690
work for you at a very low heat load.

1029
01:08:46,725 --> 01:08:49,040
So it has the capability of getting rid of
a lot of heat.

1030
01:08:49,075 --> 01:08:52,210
If you don't want it to get rid of that much
heat, because you don't have it, then you

1031
01:08:52,245 --> 01:08:54,330
have to go to bypass system.

1032
01:08:54,365 --> 01:08:56,600
Anyway, the next thing in the loop is the
GSE heat exchanger.

1033
01:08:56,635 --> 01:09:01,980
On the ground you don't have radiators working
so you use the GSE heat exchanger.

1034
01:09:02,015 --> 01:09:04,400
Then there is the ammonia boiler.

1035
01:09:04,435 --> 01:09:11,400
When you reenter the ammonia boiler gives
you the ability to operate with an evaporative

1036
01:09:11,440 --> 01:09:18,440
heat sink prior to the connection of the GSE,
and so it is part of the thermal control system.

1037
01:09:22,040 --> 01:09:23,370
The next is the flash evaporator.

1038
01:09:23,405 --> 01:09:27,870
And you'll notice there are two flash chambers
here.

1039
01:09:27,905 --> 01:09:30,540
One is called the high load and one is called
the topper.

1040
01:09:30,575 --> 01:09:33,190
And I will talk about that a little more later.

1041
01:09:33,225 --> 01:09:37,500
Then the nice cool liquid, however it was
cooled, all these cool it.

1042
01:09:37,535 --> 01:09:40,170
However it was cooled is then available for
the vehicle.

1043
01:09:40,205 --> 01:09:44,150
And there is one more little heat load, and
that is the cryogenic oxygen that we're bringing

1044
01:09:44,185 --> 01:09:45,480
in.

1045
01:09:45,515 --> 01:09:48,350
We also warm it up with this coolant loop.

1046
01:09:48,385 --> 01:09:52,890
So the flow then goes to the aft cold plates.

1047
01:09:52,925 --> 01:09:57,620
And then the flow also goes to the cabin heat
exchanger and the payload heat exchanger.

1048
01:09:57,655 --> 01:09:59,800
You notice these are either or.

1049
01:09:59,835 --> 01:10:03,560
And that's because sometimes you don't even
have a payload heat exchanger use so you don't

1050
01:10:03,595 --> 01:10:04,280
use it.

1051
01:10:04,315 --> 01:10:07,060
Sometimes you have a lot of use for it.

1052
01:10:07,095 --> 01:10:11,310
And maybe, for example, SpaceLab and Space
Station have kind of an arrangement.

1053
01:10:11,345 --> 01:10:14,580
You wouldn't be in the cabin as much so you
can divert that.

1054
01:10:14,615 --> 01:10:19,030
It allows you to use the capacity in either
of two places here.

1055
01:10:19,065 --> 01:10:23,830
Then you come on down and come through your
pumping package, there are redundant pumps.

1056
01:10:23,865 --> 01:10:30,830
Then you go the fuel cell heat exchanger because
now you've used the nice cold fluid up.

1057
01:10:37,060 --> 01:10:40,190
And so the fuel cell can stand the warmer
temperatures.

1058
01:10:40,225 --> 01:10:41,370
Also some cold plates.

1059
01:10:41,405 --> 01:10:47,580
Now, it might have occurred to you, it occurred
to me, why did we waste our nice cold fluid

1060
01:10:47,615 --> 01:10:49,040
on these cold plates?

1061
01:10:49,075 --> 01:10:53,310
Why didn't we put those cold plates down here
so we could have had more cold fluid for our

1062
01:10:53,345 --> 01:10:54,490
cabin heat exchangers?

1063
01:10:54,525 --> 01:10:57,110
And the answer is geometry.

1064
01:10:57,145 --> 01:10:59,670
Those are way in the back.

1065
01:10:59,705 --> 01:11:00,890
The cabin is in the front.

1066
01:11:00,925 --> 01:11:06,590
After you've come forward from the flash evaporator,
which is in the back, to the cabin, you don't

1067
01:11:06,625 --> 01:11:08,490
want to go back to pick this up.

1068
01:11:08,525 --> 01:11:11,110
You wouldn't want to have to go back to the
back of the vehicle and then back forward

1069
01:11:11,145 --> 01:11:14,250
again, so this is a geometry problem.

1070
01:11:14,285 --> 01:11:15,010
We have cold plates here.

1071
01:11:15,045 --> 01:11:16,140
We also have cold plates here.

1072
01:11:16,175 --> 01:11:17,580
They come forward.

1073
01:11:17,615 --> 01:11:22,340
The hydraulics heat exchanger is the last
thing on the loop and then back to the radiators.

1074
01:11:22,375 --> 01:11:26,020
We will talk about that a little more.

1075
01:11:26,055 --> 01:11:32,190
The functions of the active thermal control
system.

1076
01:11:32,225 --> 01:11:33,560
Collect the waste energy from all the systems.

1077
01:11:33,595 --> 01:11:34,640
We just talked about that.

1078
01:11:34,675 --> 01:11:36,330
And rejected radiatively to space.

1079
01:11:36,365 --> 01:11:38,520
That is our first choice.

1080
01:11:38,555 --> 01:11:41,140
Our first choice is to use the radiators.

1081
01:11:41,175 --> 01:11:45,940
It turns out that the radiators in some heat
load environments don't do the job.

1082
01:11:45,975 --> 01:11:52,000
You have a high load and a bad environment,
you cannot get rid of all the heat.

1083
01:11:52,035 --> 01:11:57,130
Also, we are producing a lot of water, so
something constructive has to be done with

1084
01:11:57,165 --> 01:11:58,040
this water.

1085
01:11:58,075 --> 01:12:01,440
The fuel cells are pumping it out because
every time you make a kilowatt you've got

1086
01:12:01,475 --> 01:12:02,410
more water to use.

1087
01:12:02,445 --> 01:12:06,790
So we decided to augment the space radiators
with the evaporative heat sink at these high

1088
01:12:06,825 --> 01:12:08,140
load cases.

1089
01:12:08,175 --> 01:12:15,140
This gives us an ability to accept a radiator
system that cannot really do the job by itself

1090
01:12:16,630 --> 01:12:21,510
but make it completely adequate for some of
the low heat load cases, but in the high heat

1091
01:12:21,545 --> 01:12:24,860
load cases then it is augmented by water.

1092
01:12:24,895 --> 01:12:28,600
Now, when you want to get rid of water and
you don't have some of this bad environment

1093
01:12:28,635 --> 01:12:31,650
you can actually throttle the radiators down.

1094
01:12:31,685 --> 01:12:36,150
And, if you throttle them down, then you force
the evaporative heat sink to come online and

1095
01:12:36,185 --> 01:12:36,960
do the job for you.

1096
01:12:36,995 --> 01:12:41,310
In other words, you change the set point on
the radiator.

1097
01:12:41,345 --> 01:12:43,750
Normally we use 40 degrees set point.

1098
01:12:43,785 --> 01:12:49,500
If you change it to 56 degrees and let the
water take you from 56 back down to 40 then

1099
01:12:49,535 --> 01:12:51,340
you artificially get rid of water.

1100
01:12:51,375 --> 01:12:54,850
It is a good water dump system.

1101
01:12:54,885 --> 01:13:00,710
During ascent, over 100,000 feet we use the
water boiler.

1102
01:13:00,745 --> 01:13:01,420
The flash evaporator.

1103
01:13:01,455 --> 01:13:03,100
Not a water boiler.

1104
01:13:03,135 --> 01:13:04,600
That's a Freudian slip, I guess.

1105
01:13:04,635 --> 01:13:07,650
The Apollo had what's called a water boiler.

1106
01:13:07,685 --> 01:13:08,500
It was a nightmare.

1107
01:13:08,535 --> 01:13:13,770
We said never will we do that again, so we
ended up with a different design for the Shuttle.

1108
01:13:13,805 --> 01:13:20,330
The reentry system below 100,000 feet is ammonia.

1109
01:13:20,365 --> 01:13:26,240
It will carry you all the way to the ground
and on the ground until you get the GSE.

1110
01:13:26,275 --> 01:13:30,040
Water won't carry you because water won't
evaporate less than 100,000 feet, but the

1111
01:13:30,075 --> 01:13:34,560
ammonia will so that's the reason it is there.

1112
01:13:34,595 --> 01:13:37,480
Let's talk about the radiators themselves.

1113
01:13:37,515 --> 01:13:40,750
The two payload bay doors are a mirror image
of each other.

1114
01:13:40,785 --> 01:13:44,620
They are radiators on each side that are exactly
mirror image.

1115
01:13:44,655 --> 01:13:51,620
I don't know what happened there.

1116
01:13:52,900 --> 01:13:59,900
Anyway, this is supposed to say that the radiators
on these two sides are mounted and are plumbed

1117
01:14:01,290 --> 01:14:04,120
in two separate cooling loops.

1118
01:14:04,155 --> 01:14:08,020
The reason for that is there is always a redundant
loop.

1119
01:14:08,055 --> 01:14:11,120
Obviously, you have to be able to take a failure
and still have a good system.

1120
01:14:11,155 --> 01:14:15,940
If you run both loops through both radiator
sides and you took some sort of collision

1121
01:14:15,975 --> 01:14:19,870
hit then you could wipe out both of your cooling
loops in one hit.

1122
01:14:19,905 --> 01:14:20,930
And so that is unacceptable.

1123
01:14:20,965 --> 01:14:27,930
By plumbing the systems up with mirror image
radiator systems on different loops then you

1124
01:14:28,370 --> 01:14:31,640
can still use the capacity together.

1125
01:14:31,675 --> 01:14:34,730
But if you lose one side you still have half
your capacity left.

1126
01:14:34,765 --> 01:14:37,290
And plus you have your evaporative heat sinks
to make up the difference.

1127
01:14:37,325 --> 01:14:43,850
So we can survive with a door out.

1128
01:14:43,885 --> 01:14:46,410
I mentioned the dual set points before.

1129
01:14:46,445 --> 01:14:49,270
I also mentioned the bypass thermal control.

1130
01:14:49,305 --> 01:14:52,230
I mentioned the dual set points, 40 and 56.

1131
01:14:52,265 --> 01:14:53,620
40 is our normal.

1132
01:14:53,655 --> 01:14:59,960
If you're trying to burn up some water you
go to 56 and you use the difference in water.

1133
01:14:59,995 --> 01:15:04,000
The radiators, we have two different kinds
of radiators.

1134
01:15:04,035 --> 01:15:09,180
We have the single-sided that are on the back
of the vehicle and some two-sided ones on

1135
01:15:09,215 --> 01:15:10,080
the front of the vehicle.

1136
01:15:10,115 --> 01:15:17,080
The reason for that is when you open the door
you expose the underside of the door.

1137
01:15:18,870 --> 01:15:22,520
If you have radiators on the underside of
the door then you've exposed your radiators.

1138
01:15:22,555 --> 01:15:29,520
But if you lift the radiator panel off the
door, because the doors go way down, then

1139
01:15:30,420 --> 01:15:31,730
you can see the underside.

1140
01:15:31,765 --> 01:15:36,440
It's not as good, you don't get a full view
of the heavens, but it does get rid of heat.

1141
01:15:36,475 --> 01:15:40,320
And so we needed that extra capacity.

1142
01:15:40,355 --> 01:15:47,320
On the front four panels they are the two-sided
and on the back four they are single-sided.

1143
01:15:47,500 --> 01:15:50,980
The radiators themselves are made out of a
honeycomb aluminum structure.

1144
01:15:51,015 --> 01:15:55,900
The tubes were imbedded in the structure so
that the surface was smooth, and that was

1145
01:15:55,935 --> 01:16:01,850
because we wanted to use a silver Teflon tape
for our thermal control coding.

1146
01:16:01,885 --> 01:16:08,180
For previous vehicles we always painted the
radiators, painted them white.

1147
01:16:08,215 --> 01:16:13,120
If you look at the alpha epsilon white paint,
it is pretty good.

1148
01:16:13,155 --> 01:16:19,710
I think Apollo was 0.18 alpha and epsilon
about 0.92.

1149
01:16:19,745 --> 01:16:22,040
That's pretty good.

1150
01:16:22,075 --> 01:16:23,480
The market had moved along.

1151
01:16:23,515 --> 01:16:30,480
Technology had advanced and there was not
the silver Teflon out there.

1152
01:16:30,800 --> 01:16:34,790
And what the silver Teflon does is the silver
gives you the reflection which is good and

1153
01:16:34,825 --> 01:16:41,250
the Teflon gives you the radiation which is
good, so you get the best of both worlds.

1154
01:16:41,285 --> 01:16:48,250
Silver Teflon was about 0.05 epsilon and about
0.88, 0.9, something like that.

1155
01:16:51,900 --> 01:16:57,120
You lost a slight amount in epsilon and gained
a lot in alpha, so basically you could ignore

1156
01:16:57,155 --> 01:17:01,470
the sun which is what you'd like to do, is
ignore the sun.

1157
01:17:01,505 --> 01:17:04,770
It turned out the silver Teflon had some issues.

1158
01:17:04,805 --> 01:17:07,560
We tested the radiators.

1159
01:17:07,595 --> 01:17:14,560
The radiator was not a slam dunk with eight
panels, four of which are two-sided.

1160
01:17:17,140 --> 01:17:19,940
Effectively you have 12 panels.

1161
01:17:19,975 --> 01:17:22,880
You have fluid going through those in parallel
tubes.

1162
01:17:22,915 --> 01:17:28,210
You're trying to guaranty that the fluid all
goes where it's supposed to go.

1163
01:17:28,245 --> 01:17:34,580
And, therefore, the viscosity of Freon, which
is very low, analytically said it was all

1164
01:17:34,615 --> 01:17:34,890
right.

1165
01:17:34,925 --> 01:17:40,510
But we wanted some testing to prove it so
we did test the entire radiator system.

1166
01:17:40,545 --> 01:17:42,550
And, in that test, all the silver Teflon fell
off.

1167
01:17:42,585 --> 01:17:49,350
It is a really good thermal coating but it
doesn't seem to be very practical.

1168
01:17:49,385 --> 01:17:52,500
It turned out that the problem was adhesive.

1169
01:17:52,535 --> 01:17:56,900
We did a little adhesive work and the materials
people came up with a Permacel that worked

1170
01:17:56,935 --> 01:17:58,170
perfectly.

1171
01:17:58,205 --> 01:17:59,370
They have never come off again.

1172
01:17:59,405 --> 01:18:04,480
In fact, we get 10, 12 years out of the radiators,
lots of time.

1173
01:18:04,515 --> 01:18:11,480
The problem that the Permacel couldn't solve
was beneath the tape you could get very small

1174
01:18:14,750 --> 01:18:19,270
little out-gassing of the materials.

1175
01:18:19,305 --> 01:18:21,150
Almost all materials outgas some.

1176
01:18:21,185 --> 01:18:23,980
Basically, we would put bubbles underneath
the tape.

1177
01:18:24,015 --> 01:18:27,150
We went to a perforated.

1178
01:18:27,185 --> 01:18:31,250
There are millions of little holes in this
tape.

1179
01:18:31,285 --> 01:18:35,540
And it is placed on the vehicle and it stayed
on just fine.

1180
01:18:35,575 --> 01:18:40,520
It wasn't very long, though, that people began
to worry about the focusing of this silver,

1181
01:18:40,555 --> 01:18:42,440
that the doors are curved upward.

1182
01:18:42,475 --> 01:18:46,030
And so there is a focal point there that is
a very, very hot point.

1183
01:18:46,065 --> 01:18:49,350
And there was concern that that's really not
a good thing to have.

1184
01:18:49,385 --> 01:18:54,980
If we could make the surface less specular
and more diffuse without losing the alpha

1185
01:18:55,015 --> 01:18:56,510
and epsilon we would have a better design.

1186
01:18:56,545 --> 01:18:57,880
And so they dimpled it.

1187
01:18:57,915 --> 01:19:04,250
Now we have Permacel dimpled, perforated silver
Teflon tape.

1188
01:19:04,285 --> 01:19:10,820
It works great.

1189
01:19:10,855 --> 01:19:14,560
The flash evaporator.

1190
01:19:14,595 --> 01:19:18,210
Water is the flash evaporator's evaporant.

1191
01:19:18,245 --> 01:19:19,850
This was a brand-new design.

1192
01:19:19,885 --> 01:19:22,310
The water boiler on Apollo was no good.

1193
01:19:22,345 --> 01:19:24,840
It was a problem.

1194
01:19:24,875 --> 01:19:27,080
The flash evaporator is a very simple concept.

1195
01:19:27,115 --> 01:19:28,520
You have a chamber.

1196
01:19:28,555 --> 01:19:30,960
You run your coolant around the chamber that
you want to be cooled.

1197
01:19:30,995 --> 01:19:33,940
And you spray water on the walls of the chamber.

1198
01:19:33,975 --> 01:19:37,250
And, if the pressures are all right, the water
will flash.

1199
01:19:37,285 --> 01:19:38,360
You won't get ice.

1200
01:19:38,395 --> 01:19:42,980
It will go straight to steam.

1201
01:19:43,015 --> 01:19:45,750
Steam will go overboard and it will all be
wonderful.

1202
01:19:45,785 --> 01:19:51,560
And if you can convince a program manager
of that good luck.

1203
01:19:51,595 --> 01:19:54,180
Anyway, the way to convince a program manager
is to show him good test data.

1204
01:19:54,215 --> 01:20:01,180
During the development, we developed this
process of spraying the walls and not getting

1205
01:20:02,730 --> 01:20:06,630
water carryover which will obviously freeze
up your steam duct.

1206
01:20:06,665 --> 01:20:09,170
Which you don't want.

1207
01:20:09,205 --> 01:20:16,170
But, as the design evolved, we had to get
more sophisticated because we needed this

1208
01:20:17,760 --> 01:20:23,210
flash evaporator to burn up the extra water
when we didn't need the fuel cell water.

1209
01:20:23,245 --> 01:20:26,010
And we did that with that 40 to 56 set point.

1210
01:20:26,045 --> 01:20:30,170
And so we needed a small evaporator that could
handle that.

1211
01:20:30,205 --> 01:20:33,290
It was called the "topper." It tops off the
radiator.

1212
01:20:33,325 --> 01:20:37,480
But when the doors are closed there is nothing
else to get rid of your heat, now you need

1213
01:20:37,515 --> 01:20:38,980
a loss of capacity.

1214
01:20:39,015 --> 01:20:43,680
And so the second chamber was the hallowed
chamber.

1215
01:20:43,715 --> 01:20:45,360
Together they do the whole job.

1216
01:20:45,395 --> 01:20:52,320
When the radiators are working only topper,
you can come home with this system functional

1217
01:20:52,355 --> 01:20:54,190
and make it home.

1218
01:20:54,225 --> 01:20:57,830
It turns out we never did freeze up the steam
duct so that part was good.

1219
01:20:57,865 --> 01:21:02,500
It turns out that we had some freezing in
the chamber.

1220
01:21:02,535 --> 01:21:09,500
And, in fact, we had to develop a process
that acknowledged that that could occur.

1221
01:21:11,050 --> 01:21:12,030
And how would we flush it?

1222
01:21:12,065 --> 01:21:15,070
It is called "flushing." And so we did develop
a process.

1223
01:21:15,105 --> 01:21:16,590
And it has never failed.

1224
01:21:16,625 --> 01:21:18,350
The flushing process always works.

1225
01:21:18,385 --> 01:21:23,140
And we have had on several occasions, I probably
cannot count them for you, but four of five

1226
01:21:23,175 --> 01:21:30,140
times maybe over the Shuttle flights we've
had some freezing inside the cavities.

1227
01:21:31,050 --> 01:21:33,450
There is a non-propulsive overboard vent.

1228
01:21:33,485 --> 01:21:38,100
That was the one going out both sides for
the topper because it could be used for very

1229
01:21:38,135 --> 01:21:41,750
long times during the mission and you might
be pointing or whatever you might be doing.

1230
01:21:41,785 --> 01:21:46,350
But when you're coming home the high load
is just a big out the side of the vehicle

1231
01:21:46,385 --> 01:21:50,580
type duct.

1232
01:21:50,615 --> 01:21:53,400
The ammonia boiler, its heat sink is ammonia.

1233
01:21:53,435 --> 01:21:58,440
As I mentioned before, it evaporates all the
way to the ground where the water won't.

1234
01:21:58,475 --> 01:22:00,270
The redundant boiler is here.

1235
01:22:00,305 --> 01:22:02,450
Up here there are no redundant boilers.

1236
01:22:02,485 --> 01:22:05,060
These two chambers have redundant everything.

1237
01:22:05,095 --> 01:22:10,960
They have redundant feed water systems and
redundant control systems, redundant spray

1238
01:22:10,995 --> 01:22:14,120
nozzles, redundant everything, but the chamber
is a chamber.

1239
01:22:14,155 --> 01:22:14,660
You get what you get.

1240
01:22:14,695 --> 01:22:19,460
They are redundant boilers is the way the
ammonia boiler gets its redundancy.

1241
01:22:19,495 --> 01:22:26,290
It was designed to be utilized during entry
and on the runway until the cooling is available.

1242
01:22:26,325 --> 01:22:29,100
It turns out that we don't do that anymore.

1243
01:22:29,135 --> 01:22:35,510
It turns out operationally we learned that
if we cold soak the radiators before we shut

1244
01:22:35,545 --> 01:22:41,560
the doors and then bypass them and come home
on the flash evaporator that there is a lot

1245
01:22:41,595 --> 01:22:43,410
of heat capacity still left in those radiators.

1246
01:22:43,445 --> 01:22:46,950
There is a lot of fluid out there and it is
cold.

1247
01:22:46,985 --> 01:22:53,950
And so we can actually go all the way to wheel
stop on the radiator.

1248
01:22:54,510 --> 01:22:58,340
And so at 175,000 feet we start flowing the
radiator.

1249
01:22:58,375 --> 01:23:04,650
And at 100,000 feet the flash evaporator is
off and we cold soak all the way home.

1250
01:23:04,685 --> 01:23:11,650
And after wheel stop the ammonia boiler cranks
up.

1251
01:23:12,380 --> 01:23:15,070
I mentioned the Freon 21, the low viscosity.

1252
01:23:15,105 --> 01:23:18,190
We got an excellent performance out of that.

1253
01:23:18,225 --> 01:23:21,790
The low viscosity is really, really important,
as much parallelism as we have.

1254
01:23:21,825 --> 01:23:23,640
I didn't really give you the numbers.

1255
01:23:23,675 --> 01:23:25,690
In the single panels we have 26 tubes.

1256
01:23:25,725 --> 01:23:32,550
In the two-sided panels, I believe, there
are 66 tubes.

1257
01:23:32,585 --> 01:23:33,290
Lots of tubes.

1258
01:23:33,325 --> 01:23:34,230
Lots of parallelism.

1259
01:23:34,265 --> 01:23:40,970
It is awfully easy to get flow instability
in a thermal system like that but the Freon

1260
01:23:41,005 --> 01:23:41,540
loop does great.

1261
01:23:41,575 --> 01:23:48,120
We have redundant pumps, all liquid heat exchangers
and cold plates.

1262
01:23:48,155 --> 01:23:50,330
This is that chamber that I told you.

1263
01:23:50,365 --> 01:23:54,620
If you can look right down here, this is one
person.

1264
01:23:54,655 --> 01:23:57,190
In fact, there is a radiator panel.

1265
01:23:57,225 --> 01:23:59,310
This was during buildup.

1266
01:23:59,345 --> 01:24:04,330
Twice we tested the flash evaporator in this
environment once as part of the integrated

1267
01:24:04,365 --> 01:24:07,990
system with all the radiators and once by
itself.

1268
01:24:08,025 --> 01:24:12,350
And twice we tested the radiators, one as
part of the integrated system and once by

1269
01:24:12,385 --> 01:24:13,010
themselves.

1270
01:24:13,045 --> 01:24:16,490
So we did essentially three large tests.

1271
01:24:16,525 --> 01:24:21,050
And the one that had the entire system in
it, had all the cold plates, had everything

1272
01:24:21,085 --> 01:24:26,210
in it, as I said, is the most sophisticated
thermal test we've ever done at JSC.

1273
01:24:26,245 --> 01:24:29,480
And it proved that the system could work.

1274
01:24:29,515 --> 01:24:34,560
It also proved that we had to tune the flash
evaporator nozzle because it was wrong.

1275
01:24:34,595 --> 01:24:38,850
But we did get the data, we did prove it was
wrong and we got it re-machined.

1276
01:24:38,885 --> 01:24:42,660
A machine out of columbium, somebody else
will have to answer why.

1277
01:24:42,695 --> 01:24:47,730
And so it was a problem for Aaron to go get
us another one, but it fixed it and it was

1278
01:24:47,765 --> 01:24:48,210
successful.

1279
01:24:48,245 --> 01:24:53,480
[AUDIENCE QUESTION]

1280
01:24:53,515 --> 01:24:57,900
You can have a command module and a service
module and a stack configuration in side that

1281
01:24:57,935 --> 01:24:59,340
chamber.

1282
01:24:59,375 --> 01:25:03,400
And it had a solar and full vacuum.

1283
01:25:03,435 --> 01:25:05,690
[AUDIENCE QUESTION]

1284
01:25:05,725 --> 01:25:07,770
It was a manned chamber then.

1285
01:25:07,805 --> 01:25:09,980
It is not now.

1286
01:25:10,015 --> 01:25:13,870
After Apollo-Soyuz, it hasn't been manned
since then.

1287
01:25:13,905 --> 01:25:16,250
It's still available for testing but is not
manned.

1288
01:25:16,285 --> 01:25:20,850
It has a sister chamber 100 feet that way
where all of the EVA testing is done.

1289
01:25:20,885 --> 01:25:24,550
A good example, I think, of how the Shuttle
Program built on a lot of Apollo-- The same

1290
01:25:24,585 --> 01:25:31,550
thing at the Cape where a lot of the launch
hardware was adapted is the Shuttle Program,

1291
01:25:39,420 --> 01:25:46,420
you know, you heard about the budgetary constraints.

1292
01:25:55,850 --> 01:25:56,100
The Shuttle Program never could have afforded
to build something like that.

1293
01:25:55,850 --> 01:25:56,100
But luckily a lot of this equipment was built
during Apollo when the money was much more

1294
01:25:55,850 --> 01:25:56,100
available.

1295
01:25:55,850 --> 01:25:59,350
If you have been keeping count, we're getting
toward the end here.

1296
01:25:59,385 --> 01:26:06,350
I did want to mention, before we left the
main orbiter systems, that there was some

1297
01:26:06,820 --> 01:26:09,990
rotating equipment life testing that we did
for the program.

1298
01:26:10,025 --> 01:26:13,170
The equipment we're talking about here is
the cabin fan, the water gas separators, the

1299
01:26:13,205 --> 01:26:17,340
avionics bay fans, cabin coolant and the vehicle
coolant pumps.

1300
01:26:17,375 --> 01:26:22,260
The life requirement was 100 missions, and
that was calculated by somebody to be 20,000

1301
01:26:22,295 --> 01:26:22,820
hours.

1302
01:26:22,855 --> 01:26:28,900
If you could show 20,000 hours of successful
operation, you had the design life of the

1303
01:26:28,935 --> 01:26:29,980
hardware.

1304
01:26:30,015 --> 01:26:34,700
We set up a laboratory to run the equipment.

1305
01:26:34,735 --> 01:26:37,900
It was obviously a low-maintenance lab.

1306
01:26:37,935 --> 01:26:42,960
We collected data and checked in the room
occasionally to see if everything was all

1307
01:26:42,995 --> 01:26:43,680
right.

1308
01:26:43,715 --> 01:26:49,590
It turned out that all the equipment passed
the 20,000 hour requirement.

1309
01:26:49,625 --> 01:26:52,650
We did learn something, though, that some
of that stuff was so noisy.

1310
01:26:52,685 --> 01:26:55,080
Oh, it was noisy.

1311
01:26:55,115 --> 01:27:02,080
There was some work done on some muffling,
but the hardware itself was all good.

1312
01:27:04,540 --> 01:27:05,370
We are at the end.

1313
01:27:05,405 --> 01:27:05,880
Yes.

1314
01:27:05,915 --> 01:27:08,710
Were there noise requirements [AUDIENCE QUESTION]?

1315
01:27:08,745 --> 01:27:12,040
Yes, there was a cabin noise spec.

1316
01:27:12,075 --> 01:27:14,530
And, yes, it had to be met.

1317
01:27:14,565 --> 01:27:16,590
And I don't remember how it was met.

1318
01:27:16,625 --> 01:27:17,870
We put mufflers on some of the equipment.

1319
01:27:17,905 --> 01:27:23,920
Maybe some insulation inside of the ducting,
I'm not sure.

1320
01:27:23,955 --> 01:27:26,830
If we have time, COHEN: I will tell a little
anecdote here.

1321
01:27:26,865 --> 01:27:30,600
I chaired the Change Control Board.

1322
01:27:30,635 --> 01:27:32,740
[NOISE OBSCURES]

1323
01:27:32,775 --> 01:27:39,740
The medical organization came to see me and
said that the cabin was very, very noisy and

1324
01:27:40,330 --> 01:27:45,370
it was going to really do a detriment to the
astronauts.

1325
01:27:45,405 --> 01:27:52,370
And it was very expensive in terms of dollars
and weight to really get all the cabin fans

1326
01:27:53,910 --> 01:27:59,190
and cabin environment down to the level they
wanted.

1327
01:27:59,225 --> 01:28:00,090
I thought for a moment.

1328
01:28:00,125 --> 01:28:03,260
I go out to California a lot.

1329
01:28:03,295 --> 01:28:08,760
I go out to Rockwell and stay in motels that
are on the Los Angeles freeway.

1330
01:28:08,795 --> 01:28:15,760
And I said you don't see me worried about
my ears in staying in those freeways and not

1331
01:28:16,080 --> 01:28:18,490
being able to sleep and having all that noise.

1332
01:28:18,525 --> 01:28:22,980
And the doctor looked at me for a moment and
said, well, you're already deaf.

1333
01:28:23,015 --> 01:28:26,060
And I said what did you say?

1334
01:28:26,095 --> 01:28:30,740
But we did have to make some modifications
of it to actually reduce noise.

1335
01:28:30,775 --> 01:28:32,480
Let me interject one item.

1336
01:28:32,515 --> 01:28:35,220
I think somebody asked the issue about the
IMU.

1337
01:28:35,255 --> 01:28:41,880
We decided to pick the IMU off the shelves,
and it was air-cooled, to really do it right.

1338
01:28:41,915 --> 01:28:48,050
If we would have done it right, we would have
picked an IMU which was compatible with liquid

1339
01:28:48,085 --> 01:28:49,910
cooling rather than redesign it.

1340
01:28:49,945 --> 01:28:53,910
But we decided to stick with the IMU that
was air-cooled.

1341
01:28:53,945 --> 01:28:56,540
Whether that was the right decision to make,
I don't know.

1342
01:28:56,575 --> 01:29:00,100
It seemed like it was because I think we've
only had one problem with an IMU.

1343
01:29:00,135 --> 01:29:02,580
I don't think we've had many problems with
the IMU.

1344
01:29:02,615 --> 01:29:06,920
But that is a little anecdote that I thought
of.

1345
01:29:06,955 --> 01:29:10,130
That's a program manager's trait.

1346
01:29:10,165 --> 01:29:14,550
Probably the air-cooled IMU was a less expensive
option.

1347
01:29:14,585 --> 01:29:21,550
It might have cost a little in terms of thermal
efficiency, but that is only energy power.

1348
01:29:21,840 --> 01:29:26,670
And power was available so it was a good tradeoff.

1349
01:29:26,705 --> 01:29:31,400
This is the last of the subsystem areas.

1350
01:29:31,435 --> 01:29:33,850
This is the EVA airlock support.

1351
01:29:33,885 --> 01:29:38,590
The Environmental Thermal Control and Life
Support System does support the airlock.

1352
01:29:38,625 --> 01:29:45,590
It maintains the cabin pressure and composition
during the airlock repress and depress.

1353
01:29:45,870 --> 01:29:52,870
This is really a requirement back on the ARS
and the pressure and composition control system

1354
01:29:53,130 --> 01:29:58,930
because airlock use basically dumps cabin
gas and then you repress the airlock.

1355
01:29:58,965 --> 01:30:04,910
It is a requirement that you cannot upset
the cabin while you're doing the EVA function.

1356
01:30:04,945 --> 01:30:08,570
We also provide the service and cooling umbilical.

1357
01:30:08,605 --> 01:30:12,610
If you have any kind of mental picture of
being in the airlock, the crew is connected

1358
01:30:12,645 --> 01:30:18,040
with cooling and oxygen through an umbilical
so they don't use the consumables in their

1359
01:30:18,075 --> 01:30:20,140
spacesuit.

1360
01:30:20,175 --> 01:30:23,970
And so that is provided by the ETCLSS.

1361
01:30:24,005 --> 01:30:27,590
Heat rejection, the crew wears a liquid cooling
garment.

1362
01:30:27,625 --> 01:30:33,360
And the cooling for that is done by the vehicle
until you go EVA, of course.

1363
01:30:33,395 --> 01:30:33,950
Then the recharge.

1364
01:30:33,985 --> 01:30:39,930
We supply the backpack O2 recharge from the
900 PSI cryo.

1365
01:30:39,965 --> 01:30:42,590
We supply the water to recharge for the sublimator.

1366
01:30:42,625 --> 01:30:49,360
NASA is overrun with acronyms.

1367
01:30:49,395 --> 01:30:54,340
EMU is extra vehicular mobility unit, which
means nothing but spacesuit and backpack.

1368
01:30:54,375 --> 01:30:58,570
So the spacesuit and backpack uses an evaporative
heat sink and it uses a sublimator.

1369
01:30:58,605 --> 01:31:05,570
And the idea there is it's a device that exposes
a layer of ice to space and then it sublimates

1370
01:31:05,950 --> 01:31:12,080
and you get your cooling from that as opposed
to putting a liquid water on a surface and

1371
01:31:12,115 --> 01:31:12,540
flashing it.

1372
01:31:12,575 --> 01:31:16,110
Anyway, that has to be serviced.

1373
01:31:16,145 --> 01:31:18,890
That water is provided from the system.

1374
01:31:18,925 --> 01:31:22,650
And then the condensate that the crew brings
back, EVA, that's a sweaty job.

1375
01:31:22,685 --> 01:31:25,190
That condensate goes back into the system.

1376
01:31:25,225 --> 01:31:31,920
So the airlock support is another part of
this system.

1377
01:31:31,955 --> 01:31:33,440
In fact, that is the sixth part.

1378
01:31:33,475 --> 01:31:34,940
So we are through.

1379
01:31:34,975 --> 01:31:37,630
This is a picture of the airlock.

1380
01:31:37,665 --> 01:31:38,340
Not really the airlock.

1381
01:31:38,375 --> 01:31:42,550
This is the test chamber that we built to
put the equipment in.

1382
01:31:42,585 --> 01:31:46,390
You'll notice it has the right hatch in it.

1383
01:31:46,425 --> 01:31:51,550
And, if you can recall back an hour and a
half ago, I showed you a picture where there

1384
01:31:51,585 --> 01:31:56,920
was this hatch basically on the backside of
the test chamber.

1385
01:31:56,955 --> 01:31:58,450
We hook those together.

1386
01:31:58,485 --> 01:32:03,200
Because, as I said, as you depress and repress
the airlock it affects the cabin.

1387
01:32:03,235 --> 01:32:06,770
So we needed a test environment that had both
those simultaneously.

1388
01:32:06,805 --> 01:32:10,570
But the difference is this has to go all the
way to vacuum.

1389
01:32:10,605 --> 01:32:14,070
So we connected this to our vacuum system.

1390
01:32:14,105 --> 01:32:18,790
And, when the crew is inside this, it is a
manned vacuum test.

1391
01:32:18,825 --> 01:32:25,790
And when the crew is inside the other test
chamber it is basically sea level or, at most,

1392
01:32:26,870 --> 01:32:30,450
8 PSI would be the lowest it would ever be.

1393
01:32:30,485 --> 01:32:36,700
And I think the last picture is a spacesuit
inside the airlock.

1394
01:32:36,735 --> 01:32:40,860
And this is just a little cutaway showing
the airlock.

1395
01:32:40,895 --> 01:32:43,540
This was mounted on the back of that chamber
you saw earlier.

1396
01:32:43,575 --> 01:32:50,540
If you bring that picture back up, I will
talk to that for just a minute and then we

1397
01:32:56,880 --> 01:32:58,580
will have some questions.

1398
01:32:58,615 --> 01:33:05,580
Before every flight, one of the things that
we do is that every EVA crewmember takes his

1399
01:33:07,870 --> 01:33:14,870
or her spacesuit into that EVA test chamber,
into the airlock test chamber so you actually

1400
01:33:15,040 --> 01:33:19,960
get a chance to take your own suit down to
vacuum.

1401
01:33:19,995 --> 01:33:26,920
And particularly, before you do your very
first EVA, it is really a confidence builder

1402
01:33:26,955 --> 01:33:32,480
because the physical sensations that you get
in a suit -- And remember you're at about

1403
01:33:32,515 --> 01:33:35,990
a 4 PSI pure oxygen environment.

1404
01:33:36,025 --> 01:33:39,090
Your body, the inside of your mouth feels
a little different.

1405
01:33:39,125 --> 01:33:44,740
There are funny sounds with the fans inside
the suit.

1406
01:33:44,775 --> 01:33:48,750
The sorts of things that you don't want to
experience the first time when you actually

1407
01:33:48,785 --> 01:33:50,950
go outside into space.

1408
01:33:50,985 --> 01:33:57,950
It is much better to do it here in a controlled
environment where if there is a problem -- Actually,

1409
01:33:58,480 --> 01:34:01,410
you are supported because of the weight of
the suit.

1410
01:34:01,445 --> 01:34:04,580
It doesn't look like there is anybody in this
suit.

1411
01:34:04,615 --> 01:34:11,260
But, when you're in this suit, you're actually
supported by a cable to the ceiling of the

1412
01:34:11,295 --> 01:34:13,940
chamber which is on quick release bolts.

1413
01:34:13,975 --> 01:34:18,760
You're suspended up here.

1414
01:34:18,795 --> 01:34:25,760
And, if you ever have a problem, they can
release this, repressurize the chamber within

1415
01:34:27,480 --> 01:34:29,270
about 30 seconds.

1416
01:34:29,305 --> 01:34:32,790
I think that's the limit for a manned rated
chamber.

1417
01:34:32,825 --> 01:34:38,750
You're going to be able to repress in about
30 seconds and then just lift you out, suit

1418
01:34:38,785 --> 01:34:43,080
and all from the top, and get you out of your
suit and get you to the medics.

1419
01:34:43,115 --> 01:34:47,210
This is just an inverted bell jar.

1420
01:34:47,245 --> 01:34:49,530
The hatch is not sealed.

1421
01:34:49,565 --> 01:34:56,530
When you depress it just like pulls it out
and seals due to the pressure difference.

1422
01:34:56,670 --> 01:34:59,600
You just lift the top off.

1423
01:34:59,635 --> 01:35:06,480
Yet another example of the extensive testing
that we go through before every mission.

1424
01:35:06,515 --> 01:35:13,480
I might add one more thing, which I forgot
actually to add earlier.

1425
01:35:14,790 --> 01:35:21,790
The manned rating is a term used in manned
spacecraft which means that you've specifically

1426
01:35:23,140 --> 01:35:30,140
tested it and said that its design is worthy
of supporting a human.

1427
01:35:31,440 --> 01:35:34,810
The airlock had to provide that function.

1428
01:35:34,845 --> 01:35:37,330
So Aaron was faced with man rating the airlock.

1429
01:35:37,365 --> 01:35:42,610
And manned test capability is very scarce.

1430
01:35:42,645 --> 01:35:48,400
In fact, JSC may be the only place anymore
that can do it.

1431
01:35:48,435 --> 01:35:54,060
Anyway, we volunteered to do that as part
of our test program as a programmatic requirement.

1432
01:35:54,095 --> 01:36:00,560
Not as testing or watching or confirming anything,
but as a prime part of the test program was

1433
01:36:00,595 --> 01:36:01,510
the manned rating of the airlock.

1434
01:36:01,545 --> 01:36:02,730
And that was done in Houston.

1435
01:36:02,765 --> 01:36:05,970
That is an interesting thought.

1436
01:36:06,005 --> 01:36:12,970
If my memory serves me correctly, one of the
problems we had in the early part of the Manned

1437
01:36:14,500 --> 01:36:21,500
Space Program was doing some chamber runs
McDonnell-Douglas with a two-gas system where

1438
01:36:23,770 --> 01:36:28,860
we actually lost the heat [NOISE OBSCURES]

1439
01:36:28,895 --> 01:36:32,990
in the chamber and almost lost a test subject.

1440
01:36:33,025 --> 01:36:37,840
And that was when Apollo decided to go to
100% oxygen.

1441
01:36:37,875 --> 01:36:38,880
And that is what led up to the fire on the
pad.

1442
01:36:38,915 --> 01:36:39,130
It went to 100% oxygen at 16 pounds per square
inch with an invert over the hatch for another

1443
01:36:38,880 --> 01:36:39,130
reason.

1444
01:36:38,880 --> 01:36:45,600
And that is really if you can realize that
100% oxygen at 16 PSI everything burns.

1445
01:36:45,635 --> 01:36:45,870
Stainless steel is not self-extinguishing
at 16 PSI.

1446
01:36:45,905 --> 01:36:47,250
And, of course, that's what we were up when
we had the Apollo I fire on the pad.

1447
01:36:47,285 --> 01:36:49,050
It was a function of doing some test work
with the combined atmosphere.

1448
01:36:49,085 --> 01:36:54,890
So you have got to be careful that sometimes
you don't over-react the thing.

1449
01:36:54,925 --> 01:37:01,890
Then we went back to a different type of atmosphere.

1450
01:37:15,030 --> 01:37:18,200
Did you have a question?

1451
01:37:18,235 --> 01:37:22,550
The systems you've been describing today seem
to take up a lot of space in the Orbiter like

1452
01:37:22,585 --> 01:37:23,830
other systems.

1453
01:37:23,865 --> 01:37:30,830
How did you negotiate and manage other subsystems
for the space and the volume in the way that

1454
01:37:34,610 --> 01:37:35,840
you wanted?

1455
01:37:35,875 --> 01:37:39,290
That is a good question but you're asking
the wrong person.

1456
01:37:39,325 --> 01:37:41,720
We are the government.

1457
01:37:41,755 --> 01:37:45,720
We hired a contractor to design the vehicle.

1458
01:37:45,755 --> 01:37:52,620
Now, the design aspects of it, the philosophy
of it, the functionality of it we were very,

1459
01:37:52,655 --> 01:37:55,840
very integral with.

1460
01:37:55,875 --> 01:38:00,410
We watched, we audited, we said that looks
smart, but we didn't go and say put that cold

1461
01:38:00,445 --> 01:38:02,710
plate here and put that heat exchanger there.

1462
01:38:02,745 --> 01:38:05,020
The vehicle integrated design was Rockwell's.

1463
01:38:05,055 --> 01:38:07,130
Let me tell you how it was done.

1464
01:38:07,165 --> 01:38:09,940
Actually, in those years we didn't have CAD/CAM
systems.

1465
01:38:09,975 --> 01:38:14,250
What we did is used everything on mockups.

1466
01:38:14,285 --> 01:38:16,320
We did mockups.

1467
01:38:16,355 --> 01:38:21,120
The system was laid out of what to do and
the functions of what they had to do and the

1468
01:38:21,155 --> 01:38:21,370
plumbing.

1469
01:38:21,260 --> 01:38:23,590
And this was all laid out on a mockup.

1470
01:38:23,625 --> 01:38:28,210
And basically that was how it was negotiated
in terms of what you need.

1471
01:38:28,245 --> 01:38:32,020
In today's environment you wouldn't do that.

1472
01:38:32,055 --> 01:38:34,170
You would use electronic capability.

1473
01:38:34,205 --> 01:38:36,300
You would use your CAD/CAM systems.

1474
01:38:36,335 --> 01:38:37,860
You would actually draw it up on your computer.

1475
01:38:37,895 --> 01:38:40,440
In fact, the 777 was built that way.

1476
01:38:40,475 --> 01:38:44,590
The 777 at Boeing, they didn't use hard mockups.

1477
01:38:44,625 --> 01:38:46,640
They used electronic mockups.

1478
01:38:46,675 --> 01:38:47,720
And that is what we would do today.

1479
01:38:47,755 --> 01:38:48,970
And it would be much easier.

1480
01:38:49,005 --> 01:38:50,810
You would probably call all the engineers
together.

1481
01:38:50,845 --> 01:38:55,410
You would sit down and show how the equipment
was laid out, get a satisfactory buyoff on

1482
01:38:55,445 --> 01:38:58,600
it and do it much more rapidly and much more
quickly.

1483
01:38:58,635 --> 01:39:04,360
In the future, what you will be doing is actually
use a CAD/CAM system or CAD system to actually

1484
01:39:04,395 --> 01:39:07,670
negotiate the space you need for it.

1485
01:39:07,705 --> 01:39:09,530
That is a good question.

1486
01:39:09,565 --> 01:39:15,710
And it was based on purely that you would
get drawings, mockups, go out and lay it out

1487
01:39:15,745 --> 01:39:17,360
in a soft mockup or hard mockup.

1488
01:39:17,395 --> 01:39:20,290
You would get the engineers to come out, the
manufacturing people to come out and say this

1489
01:39:20,325 --> 01:39:23,080
is how it is going to look and then get a
buyoff on it.

1490
01:39:23,115 --> 01:39:24,650
Today you wouldn't do it that way.

1491
01:39:24,685 --> 01:39:27,550
You would do it all electronically so it would
change.

1492
01:39:27,585 --> 01:39:29,490
Well, let me ask you a question.

1493
01:39:29,525 --> 01:39:35,430
Of all the work you've done in the Shuttle
what was your biggest concern in getting ready

1494
01:39:35,465 --> 01:39:36,600
to fly or during the flight?

1495
01:39:36,635 --> 01:39:43,600
What did you have the biggest concern about?

1496
01:39:47,210 --> 01:39:48,660
I was young and confident.

1497
01:39:48,695 --> 01:39:54,530
I don't know that I had a specific area that
I was really concerned about.

1498
01:39:54,565 --> 01:39:56,040
Like these people right here, right?

1499
01:39:56,075 --> 01:39:57,540
Young and confident.

1500
01:39:57,575 --> 01:40:03,630
I did recognize, though, but it did result
in the integrated tests that I showed.

1501
01:40:03,665 --> 01:40:09,300
I did recognize that we had the most highly
integrated thermal control system ever conceived.

1502
01:40:09,335 --> 01:40:12,840
And it had, as I said, modes within modes.

1503
01:40:12,875 --> 01:40:15,860
It changed modes with respect to the vehicle
phases.

1504
01:40:15,895 --> 01:40:19,690
It changed modes with respect to operation.

1505
01:40:19,725 --> 01:40:22,820
We had 9 PSI that went to 10.2 PSI.

1506
01:40:22,855 --> 01:40:23,590
We had 8 PSI.

1507
01:40:23,625 --> 01:40:29,440
We had thermal control loops, ammonia boilers,
flash evaporators, so I did recognize the

1508
01:40:29,475 --> 01:40:30,380
sophistication.

1509
01:40:30,415 --> 01:40:37,380
In fact, we proposed early on to use that
large chamber in an integrated vehicle test.

1510
01:40:41,680 --> 01:40:48,680
Not we, me, but the big we looked at an integrated
test like the Command Service Module was tested.

1511
01:40:49,380 --> 01:40:51,130
And that was viewed to be impractical.

1512
01:40:51,165 --> 01:40:53,380
It was cut it off at the bulkhead.

1513
01:40:53,415 --> 01:40:58,030
You could do the forward cabin part and then
do the aft section, but that was viewed to

1514
01:40:58,065 --> 01:40:58,760
be impractical.

1515
01:40:58,795 --> 01:41:02,130
But it still was a very integrated design.

1516
01:41:02,165 --> 01:41:08,140
All the systems engineering that was there
created that inner-dependency.

1517
01:41:08,175 --> 01:41:13,240
And I think I was smart enough to know that
there was certainly some potential risks there.

1518
01:41:13,275 --> 01:41:20,240
Remember in the very beginning of this I talked
about ownership of all the technical aspects?

1519
01:41:23,940 --> 01:41:25,450
We had ownership.

1520
01:41:25,485 --> 01:41:32,450
We believed that what we had done was prudent,
appropriate, and we believed it would work.

1521
01:41:32,950 --> 01:41:35,010
It wasn't like you bought something and you
hope it works.

1522
01:41:35,045 --> 01:41:39,740
Can you say a word of what you think, this
is looking in your crystal ball, about the

1523
01:41:39,775 --> 01:41:40,250
CEV?

1524
01:41:40,285 --> 01:41:44,220
Do you think it's going to have a very similar
type system or have you thought about that?

1525
01:41:44,255 --> 01:41:45,190
Well, we hope so.

1526
01:41:45,225 --> 01:41:52,190
Our new administrator has sort of back to
the grassroots philosophy, or at least right

1527
01:41:52,970 --> 01:41:53,860
now.

1528
01:41:53,895 --> 01:42:00,280
And so we hope that the CEV will be developed
with a lot of government involvement, that

1529
01:42:00,315 --> 01:42:04,570
the government will have ownership again of
the technical aspects of the design.

1530
01:42:04,605 --> 01:42:11,570
If that happens then I think a lot of the
experience that is around and a lot of the

1531
01:42:13,080 --> 01:42:16,540
free-thinking and the independence that the
government can bring to that, there is another

1532
01:42:16,575 --> 01:42:20,630
school of thought that says keep the government
out of the way and let the contractor go do

1533
01:42:20,665 --> 01:42:21,840
their thing.

1534
01:42:21,875 --> 01:42:26,720
And, obviously, you wouldn't get that position
from me but there are people that believe

1535
01:42:26,755 --> 01:42:27,420
that's the right way to do it.

1536
01:42:27,455 --> 01:42:33,150
Do you think the system will look pretty much
like this or similar to it?

1537
01:42:33,185 --> 01:42:37,630
Well, similar, yes, I do think so.

1538
01:42:37,665 --> 01:42:44,630
I believe that the very tight schedule for
the CEV is going to put a lot of pressure

1539
01:42:46,050 --> 01:42:49,420
on the program manager to go with the tried
and true.

1540
01:42:49,455 --> 01:42:53,840
So I don't think there is going to be innovation
that has risk with it.

1541
01:42:53,875 --> 01:42:58,490
Maybe there will be innovation that is good
engineering, but I think the innovation with

1542
01:42:58,525 --> 01:43:00,700
risk will be very much minimized.

1543
01:43:00,735 --> 01:43:05,690
Because taking Shuttle offline in 2010 there
is going be a lot of pressure to get this

1544
01:43:05,725 --> 01:43:06,380
vehicle finished.

1545
01:43:06,415 --> 01:43:13,380
I think that is going to breed some conservatism
on the design side.

1546
01:43:17,660 --> 01:43:24,660
We talk about considering operation while
you're doing the design, but there were always

1547
01:43:31,030 --> 01:43:32,660
things once the design was made.

1548
01:43:32,695 --> 01:43:38,590
Well, like you mention, once we came up with
a requirement for a 10.2 cabin we had to develop

1549
01:43:38,625 --> 01:43:39,350
workarounds.

1550
01:43:39,385 --> 01:43:44,220
And one of the other things that after the
system is designed, we then start to figure

1551
01:43:44,255 --> 01:43:48,210
out how can it fail and work on malfunction
procedures.

1552
01:43:48,245 --> 01:43:54,440
And I know that the malfunction procedure
for loss of two coolant loops that was probably

1553
01:43:54,475 --> 01:43:57,640
the worst simulation case that we ever had
to deal with.

1554
01:43:57,675 --> 01:44:01,930
I am curious to get your opinion.

1555
01:44:01,965 --> 01:44:08,780
Walt described how we have two independent
cooling loops so that in principle one failure

1556
01:44:08,815 --> 01:44:09,890
won't take them both out.

1557
01:44:09,925 --> 01:44:14,480
Now, I don't remember what it was, but they
did discover a single point failure somewhere

1558
01:44:14,515 --> 01:44:20,000
in there which I think was corrected but where
you could have lost both of the cooling loops

1559
01:44:20,035 --> 01:44:23,780
with a single failure.

1560
01:44:23,815 --> 01:44:26,890
The only failure I remember is one that John
Young used to worry about.

1561
01:44:26,925 --> 01:44:33,890
It had to do with if you did lose a radiator
that that could bleed your accumulator down.

1562
01:44:34,170 --> 01:44:40,280
And so they did add an isolation valve so
they can isolate the radiator side.

1563
01:44:40,315 --> 01:44:45,830
But the idea was to obviously not lose your
fluid with a single hit.

1564
01:44:45,865 --> 01:44:50,170
That even though you have a nice completely
functional thermal control system it is useless

1565
01:44:50,205 --> 01:44:52,370
because it has no fluid.

1566
01:44:52,405 --> 01:44:58,650
We did have an emergency de-orbit procedure
for loss of two Freon cooling loops.

1567
01:44:58,685 --> 01:45:03,390
And, of all the things that we practices,
that was the hairiest because it was absolutely

1568
01:45:03,425 --> 01:45:04,560
time critical.

1569
01:45:04,595 --> 01:45:09,480
At this point, you have no way of getting
heat out of the cabin so you cannot ultimately

1570
01:45:09,515 --> 01:45:11,520
cool your electronics.

1571
01:45:11,555 --> 01:45:17,400
The cabin gets hot, your electronics get hot
so you have to do an immediate de-orbit.

1572
01:45:17,435 --> 01:45:21,460
Hopefully you're within range of a landing
site.

1573
01:45:21,495 --> 01:45:27,780
And then you turn off all the equipment that
you can possibly turn off, including most

1574
01:45:27,815 --> 01:45:28,660
of your computers.

1575
01:45:28,695 --> 01:45:35,660
And, when you're riding down through entry,
you basically watch the temperature of the

1576
01:45:35,990 --> 01:45:36,240
computer.

1577
01:45:35,990 --> 01:45:42,030
And, as each computer would get up to its
failure temperature, you would then switch

1578
01:45:42,065 --> 01:45:47,940
on the next computer, transfer the data, you
know, turn off the computer which has just

1579
01:45:47,975 --> 01:45:52,250
about failed, and hopefully you could make
it to the ground.

1580
01:45:52,285 --> 01:45:59,250
And I know the instructors that would lead
us through this exercise said that the information

1581
01:45:59,350 --> 01:46:03,930
they had gotten from the thermal analyst was
that nobody was really sure whether we could

1582
01:46:03,965 --> 01:46:04,340
make it.

1583
01:46:04,375 --> 01:46:06,890
I don't know what your opinion was or not.

1584
01:46:06,925 --> 01:46:07,680
We practiced it.

1585
01:46:07,715 --> 01:46:11,940
But obviously, I think I've told you, nobody
has ever died in a simulator.

1586
01:46:11,975 --> 01:46:18,530
But you never know whether the thermal model
that they use in the simulator is really going

1587
01:46:18,565 --> 01:46:23,450
to duplicate the way the Shuttle is going
to behave in an absolute emergency situation

1588
01:46:23,485 --> 01:46:24,690
like that.

1589
01:46:24,725 --> 01:46:28,420
We survived in the simulator but I don't know
what your feeling is.

1590
01:46:28,455 --> 01:46:32,670
Well, we do address the thermal model accuracy.

1591
01:46:32,705 --> 01:46:38,190
We do specific testing to validate the thermal
model so we do have pretty good confidence

1592
01:46:38,225 --> 01:46:38,580
in those.

1593
01:46:38,615 --> 01:46:43,950
But the real issue in overheat is that when
does a piece of equipment stop working in

1594
01:46:43,985 --> 01:46:45,040
an overheat situation?

1595
01:46:45,075 --> 01:46:46,430
I mean there is no magic number.

1596
01:46:46,465 --> 01:46:51,860
It is not like at 143 degrees it is OK and
144 it is not OK.

1597
01:46:51,895 --> 01:46:57,280
And it varies with age, it varies with equipment
and it varies with a lot of things.

1598
01:46:57,315 --> 01:47:02,570
So there wasn't really a precise answer as
to how long you could keep everything functional

1599
01:47:02,605 --> 01:47:04,260
and come home.

1600
01:47:04,295 --> 01:47:05,040
Yes.

1601
01:47:05,075 --> 01:47:08,360
You talked earlier a little about oxygen and
nitrogen mixing in the cabin.

1602
01:47:08,395 --> 01:47:11,970
I was wondering if there is a way to really
study that on the ground since you're not

1603
01:47:12,005 --> 01:47:13,880
in a DoD environment.

1604
01:47:13,915 --> 01:47:18,780
How do you know there are not pockets of nitrogen
sitting around that an astronaut can stick

1605
01:47:18,815 --> 01:47:19,960
his heat into?

1606
01:47:19,995 --> 01:47:20,760
Very good.

1607
01:47:20,795 --> 01:47:22,210
I just forgot to mention that earlier.

1608
01:47:22,245 --> 01:47:29,210
The testing that we ran, we had to set it
up very carefully.

1609
01:47:55,670 --> 01:48:00,520
If you notice, there is a flight deck and
a mid-deck, so obviously buoyancy is going

1610
01:48:00,555 --> 01:48:01,750
to mix that stuff for you.

1611
01:48:01,785 --> 01:48:07,390
What we did is set up a thermal condition
where less than one degree thermal gradient

1612
01:48:07,425 --> 01:48:10,570
everywhere in there had to exist before we
ran the test.

1613
01:48:10,605 --> 01:48:17,440
And that was to guaranty that we had no help
from the naturally induced circulation.

1614
01:48:17,475 --> 01:48:18,900
But you are absolutely right.

1615
01:48:18,935 --> 01:48:24,140
That test would have been a useless test without
neutralizing the gravity effects.

1616
01:48:24,175 --> 01:48:31,140
And actually the first time that I did the
spacesuit test in there we actually used the

1617
01:48:32,660 --> 01:48:33,280
10.2 protocol.

1618
01:48:33,315 --> 01:48:40,280
So I actually had to go in the day before,
take the cabin to 10.2, spend the night and

1619
01:48:42,110 --> 01:48:45,040
then we could do just a 40 minute prebreathe.

1620
01:48:45,075 --> 01:48:52,040
For most of the other tests, when you go in,
in order to avoid the inconvenience and expense

1621
01:48:53,020 --> 01:48:56,790
of staying through the night, you go in early
in the morning.

1622
01:48:56,825 --> 01:49:00,900
And then you're coming right from a sea level
environment.

1623
01:49:00,935 --> 01:49:07,900
So, before you go down to 4 PSI in the suit,
you actually have to prebreathe pure oxygen

1624
01:49:07,950 --> 01:49:09,200
for four hours.

1625
01:49:09,235 --> 01:49:11,040
As Walt said, that was the alternative.

1626
01:49:11,075 --> 01:49:15,540
You basically just get in your suit.

1627
01:49:15,575 --> 01:49:20,260
You can either bring a book and read your
book or they will pipe music into you if you

1628
01:49:20,295 --> 01:49:25,150
want to give them a CD, or I guess there was
an audiocassette in those days, or they have

1629
01:49:25,185 --> 01:49:26,920
a little black and white TV monitor.

1630
01:49:26,955 --> 01:49:31,350
And you just sort of sit there for four hours.

1631
01:49:31,385 --> 01:49:36,100
And the problem is you're not allowed to go
to sleep.

1632
01:49:36,135 --> 01:49:40,060
That would be the easiest thing, but they
want you actually to move around because when

1633
01:49:40,095 --> 01:49:44,590
you're moving your muscles you're actually
then doing a better job of de-nitrogenating.

1634
01:49:44,625 --> 01:49:45,710
So you have to stay awake.

1635
01:49:45,745 --> 01:49:52,380
And if you don't say anything for more than
about 10 minutes they will pipe something

1636
01:49:52,415 --> 01:49:55,360
in and say, Jeff, are you awake?

1637
01:49:55,395 --> 01:49:58,760
But this was a very, very useful facility.

1638
01:49:58,795 --> 01:50:01,590
I mean they used it for all different sorts
of things.

1639
01:50:01,625 --> 01:50:07,550
And I guess that was the one new facility
which was built for the Shuttle specifically.

1640
01:50:07,585 --> 01:50:07,800
Yes.

1641
01:50:07,550 --> 01:50:12,950
Jeff mentioned several times the 10.2 and
I talked about the 9.

1642
01:50:12,985 --> 01:50:19,950
The 9 was the original design, but the issues
with the 9 PSI had to do with the oxygen percentage

1643
01:50:21,460 --> 01:50:23,130
got too high.

1644
01:50:23,165 --> 01:50:26,550
And so there was much concern about flammability.

1645
01:50:26,585 --> 01:50:33,550
The idea was if you could raise the pressure
up some to 10.2 then that would be less of

1646
01:50:33,910 --> 01:50:35,630
a flammability issue.

1647
01:50:35,665 --> 01:50:42,630
But then the problem became at 10.2 that the
suit at 4 PSI was too much of a drop.

1648
01:50:44,380 --> 01:50:50,160
If you're in the bends while diving, somebody
mentioned diving earlier, scuba, you could

1649
01:50:50,195 --> 01:50:51,140
usually use a two to one.

1650
01:50:51,175 --> 01:50:55,330
If you don't reduce pressure more than half
you're probably OK.

1651
01:50:55,365 --> 01:50:58,340
You're probably not going to get the bends,
but half of 10.2 is not 4.

1652
01:50:58,375 --> 01:51:01,260
And the suit is at 4, so there was that issue
again.

1653
01:51:01,295 --> 01:51:08,260
They raised and bumped the suit up a little
bit and got it up to 4.3 and went to 10.2

1654
01:51:08,340 --> 01:51:12,130
and developed the prebreathe protocols that
made that acceptable.

1655
01:51:12,165 --> 01:51:13,430
That is sort of how it balanced out.

1656
01:51:13,465 --> 01:51:15,200
That was another operational move later.

1657
01:51:15,235 --> 01:51:20,990
And, as Walt said, you're spending enough
time, once you get in the suit and you purge

1658
01:51:21,025 --> 01:51:25,180
all the nitrogen out, and so you're sitting
in a pure oxygen environment, you've got to

1659
01:51:25,215 --> 01:51:30,430
do a bunch of tests and check out communication
tests and cooling tests.

1660
01:51:30,465 --> 01:51:36,400
You basically are not losing much time by
having to spend 40 minutes prebreathing.

1661
01:51:36,435 --> 01:51:38,070
The whole thing worked out pretty well.

1662
01:51:38,105 --> 01:51:43,470
And it will be an interesting question on
how they designed the CEV because the CEV

1663
01:51:43,505 --> 01:51:47,880
has to be compatible with docking to the Space
Station which works at a sea level environment.

1664
01:51:47,915 --> 01:51:53,800
But, on the other hand, if you're going to
take the CEV into a situation where you want

1665
01:51:53,835 --> 01:52:00,040
to do a lot of space walks, you probably want
to be able to operate it at more like 8.5

1666
01:52:00,075 --> 01:52:07,040
or 9 PSI so that you can go right into a spacesuit
without an extensive prebreathe.

1667
01:52:08,740 --> 01:52:12,450
And, of course, people are always trying to
figure out could we design the spacesuit to

1668
01:52:12,485 --> 01:52:14,110
work at a higher pressure?

1669
01:52:14,145 --> 01:52:17,130
But then you give up maneuverability.

1670
01:52:17,165 --> 01:52:23,670
We will talk about that in another lecture
that I will be giving on EVA systems.

1671
01:52:23,705 --> 01:52:24,340
Walt, thank you very much.

1672
01:52:24,375 --> 01:52:25,050
I enjoyed it.

1673
01:52:25,085 --> 01:52:25,300
[APPLAUSE]