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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 --> 00:17:06,349
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 --> 00:17:16,619
It spins the airstream.

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

238
00:17:17,974 --> 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 --> 00:17:28,069
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 --> 00:34:08,739
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
00:34:12,143 --> 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 --> 00:34:22,268
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
00:34:30,764 --> 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
00:34:42,373 --> 00:34:42,918
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 --> 01:02:48,288
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 --> 01:04:27,038
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 --> 01:05:27,788
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 --> 01:08:09,538
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 --> 01:08:12,038
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.
And, when you reduce the heat load, you've
got to find some way to make that same radiator

1027
01:08:43,635 --> 01:08:46,690
work for you at a very low heat load.

1028
01:08:46,725 --> 01:08:49,040
So it has the capability of getting rid of
a lot of heat.

1029
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

1030
01:08:52,245 --> 01:08:54,330
have to go to bypass system.

1031
01:08:54,365 --> 01:08:56,600
Anyway, the next thing in the loop is the
GSE heat exchanger.

1032
01:08:56,635 --> 01:09:01,979
On the ground you don't have radiators working
so you use the GSE heat exchanger.

1033
01:09:02,015 --> 01:09:04,399
Then there is the ammonia boiler.

1034
01:09:04,434 --> 01:09:11,399
When you reenter the ammonia boiler gives
you the ability to operate with an evaporative

1035
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.

1036
01:09:22,040 --> 01:09:23,370
The next is the flash evaporator.

1037
01:09:23,404 --> 01:09:27,870
And you'll notice there are two flash chambers
here.

1038
01:09:27,904 --> 01:09:30,540
One is called the high load and one is called
the topper.

1039
01:09:30,575 --> 01:09:33,190
And I will talk about that a little more later.

1040
01:09:33,225 --> 01:09:37,500
Then the nice cool liquid, however it was
cooled, all these cool it.

1041
01:09:37,535 --> 01:09:40,170
However it was cooled is then available for
the vehicle.

1042
01:09:40,205 --> 01:09:44,149
And there is one more little heat load, and
that is the cryogenic oxygen that we're bringing

1043
01:09:44,184 --> 01:09:45,479
in.

1044
01:09:45,515 --> 01:09:48,350
We also warm it up with this coolant loop.

1045
01:09:48,385 --> 01:09:52,890
So the flow then goes to the aft cold plates.

1046
01:09:52,925 --> 01:09:57,620
And then the flow also goes to the cabin heat
exchanger and the payload heat exchanger.

1047
01:09:57,655 --> 01:09:59,800
You notice these are either or.

1048
01:09:59,835 --> 01:10:03,559
And that's because sometimes you don't even
have a payload heat exchanger use so you don't

1049
01:10:03,595 --> 01:10:04,280
use it.

1050
01:10:04,315 --> 01:10:07,059
Sometimes you have a lot of use for it.

1051
01:10:07,095 --> 01:10:11,309
And maybe, for example, SpaceLab and Space
Station have kind of an arrangement.

1052
01:10:11,345 --> 01:10:14,580
You wouldn't be in the cabin as much so you
can divert that.

1053
01:10:14,615 --> 01:10:19,030
It allows you to use the capacity in either
of two places here.

1054
01:10:19,065 --> 01:10:23,830
Then you come on down and come through your
pumping package, there are redundant pumps.

1055
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.

1056
01:10:37,059 --> 01:10:40,190
And so the fuel cell can stand the warmer
temperatures.

1057
01:10:40,225 --> 01:10:41,370
Also some cold plates.

1058
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

1059
01:10:47,615 --> 01:10:49,040
on these cold plates?

1060
01:10:49,075 --> 01:10:53,309
Why didn't we put those cold plates down here
so we could have had more cold fluid for our

1061
01:10:53,345 --> 01:10:54,490
cabin heat exchangers?

1062
01:10:54,525 --> 01:10:57,110
And the answer is geometry.

1063
01:10:57,145 --> 01:10:59,670
Those are way in the back.

1064
01:10:59,705 --> 01:11:00,890
The cabin is in the front.

1065
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

1066
01:11:06,625 --> 01:11:08,490
want to go back to pick this up.

1067
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

1068
01:11:11,145 --> 01:11:14,250
again, so this is a geometry problem.

1069
01:11:14,285 --> 01:11:15,010
We have cold plates here.

1070
01:11:15,045 --> 01:11:16,140
We also have cold plates here.

1071
01:11:16,175 --> 01:11:17,580
They come forward.

1072
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.

1073
01:11:22,375 --> 01:11:26,020
We will talk about that a little more.

1074
01:11:26,055 --> 01:11:32,190
The functions of the active thermal control
system.

1075
01:11:32,225 --> 01:11:33,559
Collect the waste energy from all the systems.

1076
01:11:33,595 --> 01:11:34,640
We just talked about that.

1077
01:11:34,675 --> 01:11:36,330
And rejected radiatively to space.

1078
01:11:36,365 --> 01:11:38,520
That is our first choice.

1079
01:11:38,555 --> 01:11:41,140
Our first choice is to use the radiators.

1080
01:11:41,175 --> 01:11:45,940
It turns out that the radiators in some heat
load environments don't do the job.

1081
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.

1082
01:11:52,035 --> 01:11:57,130
Also, we are producing a lot of water, so
something constructive has to be done with

1083
01:11:57,165 --> 01:11:58,040
this water.

1084
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

1085
01:12:01,475 --> 01:12:02,410
more water to use.

1086
01:12:02,445 --> 01:12:06,790
So we decided to augment the space radiators
with the evaporative heat sink at these high

1087
01:12:06,825 --> 01:12:08,140
load cases.

1088
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

1089
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

1090
01:12:21,545 --> 01:12:24,860
load cases then it is augmented by water.

1091
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

1092
01:12:28,635 --> 01:12:31,650
you can actually throttle the radiators down.

1093
01:12:31,684 --> 01:12:36,150
And, if you throttle them down, then you force
the evaporative heat sink to come online and

1094
01:12:36,184 --> 01:12:36,960
do the job for you.

1095
01:12:36,995 --> 01:12:41,309
In other words, you change the set point on
the radiator.

1096
01:12:41,345 --> 01:12:43,750
Normally we use 40 degrees set point.

1097
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

1098
01:12:49,535 --> 01:12:51,340
you artificially get rid of water.

1099
01:12:51,375 --> 01:12:54,850
It is a good water dump system.

1100
01:12:54,885 --> 01:13:00,710
During ascent, over 100,000 feet we use the
water boiler.

1101
01:13:00,745 --> 01:13:01,420
The flash evaporator.

1102
01:13:01,455 --> 01:13:03,100
Not a water boiler.

1103
01:13:03,135 --> 01:13:04,600
That's a Freudian slip, I guess.

1104
01:13:04,635 --> 01:13:07,650
The Apollo had what's called a water boiler.

1105
01:13:07,684 --> 01:13:08,500
It was a nightmare.

1106
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.

1107
01:13:13,805 --> 01:13:20,330
The reentry system below 100,000 feet is ammonia.

1108
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.

1109
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

1110
01:13:30,075 --> 01:13:34,559
ammonia will so that's the reason it is there.

1111
01:13:34,595 --> 01:13:37,480
Let's talk about the radiators themselves.

1112
01:13:37,515 --> 01:13:40,750
The two payload bay doors are a mirror image
of each other.

1113
01:13:40,785 --> 01:13:44,620
They are radiators on each side that are exactly
mirror image.

1114
01:13:44,655 --> 01:13:51,620
I don't know what happened there.

1115
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

1116
01:14:01,290 --> 01:14:04,120
in two separate cooling loops.

1117
01:14:04,155 --> 01:14:08,020
The reason for that is there is always a redundant
loop.

1118
01:14:08,055 --> 01:14:11,120
Obviously, you have to be able to take a failure
and still have a good system.

1119
01:14:11,155 --> 01:14:15,940
If you run both loops through both radiator
sides and you took some sort of collision

1120
01:14:15,975 --> 01:14:19,870
hit then you could wipe out both of your cooling
loops in one hit.

1121
01:14:19,905 --> 01:14:20,930
And so that is unacceptable.

1122
01:14:20,965 --> 01:14:27,930
By plumbing the systems up with mirror image
radiator systems on different loops then you

1123
01:14:28,370 --> 01:14:31,640
can still use the capacity together.

1124
01:14:31,675 --> 01:14:34,730
But if you lose one side you still have half
your capacity left.

1125
01:14:34,765 --> 01:14:37,290
And plus you have your evaporative heat sinks
to make up the difference.

1126
01:14:37,325 --> 01:14:43,850
So we can survive with a door out.

1127
01:14:43,885 --> 01:14:46,410
I mentioned the dual set points before.

1128
01:14:46,445 --> 01:14:49,270
I also mentioned the bypass thermal control.

1129
01:14:49,305 --> 01:14:52,230
I mentioned the dual set points, 40 and 56.

1130
01:14:52,265 --> 01:14:53,620
40 is our normal.

1131
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.

1132
01:14:59,995 --> 01:15:04,000
The radiators, we have two different kinds
of radiators.

1133
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

1134
01:15:09,215 --> 01:15:10,080
the front of the vehicle.

1135
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.

1136
01:15:18,870 --> 01:15:22,520
If you have radiators on the underside of
the door then you've exposed your radiators.

1137
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

1138
01:15:30,420 --> 01:15:31,730
you can see the underside.

1139
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.

1140
01:15:36,475 --> 01:15:40,320
And so we needed that extra capacity.

1141
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.

1142
01:15:47,500 --> 01:15:50,980
The radiators themselves are made out of a
honeycomb aluminum structure.

1143
01:15:51,015 --> 01:15:55,900
The tubes were imbedded in the structure so
that the surface was smooth, and that was

1144
01:15:55,934 --> 01:16:01,850
because we wanted to use a silver Teflon tape
for our thermal control coding.

1145
01:16:01,885 --> 01:16:08,180
For previous vehicles we always painted the
radiators, painted them white.

1146
01:16:08,215 --> 01:16:13,120
If you look at the alpha epsilon white paint,
it is pretty good.

1147
01:16:13,155 --> 01:16:19,710
I think Apollo was 0.18 alpha and epsilon
about 0.92.

1148
01:16:19,745 --> 01:16:22,040
That's pretty good.

1149
01:16:22,075 --> 01:16:23,480
The market had moved along.

1150
01:16:23,515 --> 01:16:30,480
Technology had advanced and there was not
the silver Teflon out there.

1151
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

1152
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.

1153
01:16:41,285 --> 01:16:48,250
Silver Teflon was about 0.05 epsilon and about
0.88, 0.9, something like that.

1154
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

1155
01:16:57,155 --> 01:17:01,470
the sun which is what you'd like to do, is
ignore the sun.

1156
01:17:01,505 --> 01:17:04,770
It turned out the silver Teflon had some issues.

1157
01:17:04,805 --> 01:17:07,559
We tested the radiators.

1158
01:17:07,595 --> 01:17:14,559
The radiator was not a slam dunk with eight
panels, four of which are two-sided.

1159
01:17:17,140 --> 01:17:19,940
Effectively you have 12 panels.

1160
01:17:19,975 --> 01:17:22,880
You have fluid going through those in parallel
tubes.

1161
01:17:22,915 --> 01:17:28,210
You're trying to guaranty that the fluid all
goes where it's supposed to go.

1162
01:17:28,245 --> 01:17:34,580
And, therefore, the viscosity of Freon, which
is very low, analytically said it was all

1163
01:17:34,615 --> 01:17:34,890
right.

1164
01:17:34,925 --> 01:17:40,510
But we wanted some testing to prove it so
we did test the entire radiator system.

1165
01:17:40,545 --> 01:17:42,550
And, in that test, all the silver Teflon fell
off.

1166
01:17:42,585 --> 01:17:49,350
It is a really good thermal coating but it
doesn't seem to be very practical.

1167
01:17:49,385 --> 01:17:52,500
It turned out that the problem was adhesive.

1168
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

1169
01:17:56,934 --> 01:17:58,170
perfectly.

1170
01:17:58,205 --> 01:17:59,370
They have never come off again.

1171
01:17:59,405 --> 01:18:04,480
In fact, we get 10, 12 years out of the radiators,
lots of time.

1172
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

1173
01:18:14,750 --> 01:18:19,270
little out-gassing of the materials.

1174
01:18:19,305 --> 01:18:21,150
Almost all materials outgas some.

1175
01:18:21,184 --> 01:18:23,980
Basically, we would put bubbles underneath
the tape.

1176
01:18:24,015 --> 01:18:27,150
We went to a perforated.

1177
01:18:27,184 --> 01:18:31,250
There are millions of little holes in this
tape.

1178
01:18:31,285 --> 01:18:35,540
And it is placed on the vehicle and it stayed
on just fine.

1179
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,

1180
01:18:40,555 --> 01:18:42,440
that the doors are curved upward.

1181
01:18:42,475 --> 01:18:46,030
And so there is a focal point there that is
a very, very hot point.

1182
01:18:46,065 --> 01:18:49,350
And there was concern that that's really not
a good thing to have.

1183
01:18:49,385 --> 01:18:54,980
If we could make the surface less specular
and more diffuse without losing the alpha

1184
01:18:55,015 --> 01:18:56,510
and epsilon we would have a better design.

1185
01:18:56,545 --> 01:18:57,880
And so they dimpled it.

1186
01:18:57,915 --> 01:19:04,250
Now we have Permacel dimpled, perforated silver
Teflon tape.

1187
01:19:04,285 --> 01:19:10,820
It works great.

1188
01:19:10,855 --> 01:19:14,559
The flash evaporator.

1189
01:19:14,595 --> 01:19:18,210
Water is the flash evaporator's evaporant.

1190
01:19:18,245 --> 01:19:19,850
This was a brand-new design.

1191
01:19:19,885 --> 01:19:22,309
The water boiler on Apollo was no good.

1192
01:19:22,345 --> 01:19:24,840
It was a problem.

1193
01:19:24,875 --> 01:19:27,080
The flash evaporator is a very simple concept.

1194
01:19:27,115 --> 01:19:28,520
You have a chamber.

1195
01:19:28,555 --> 01:19:30,960
You run your coolant around the chamber that
you want to be cooled.

1196
01:19:30,995 --> 01:19:33,940
And you spray water on the walls of the chamber.

1197
01:19:33,975 --> 01:19:37,250
And, if the pressures are all right, the water
will flash.

1198
01:19:37,285 --> 01:19:38,360
You won't get ice.

1199
01:19:38,395 --> 01:19:42,980
It will go straight to steam.

1200
01:19:43,015 --> 01:19:45,750
Steam will go overboard and it will all be
wonderful.

1201
01:19:45,785 --> 01:19:51,559
And if you can convince a program manager
of that good luck.

1202
01:19:51,595 --> 01:19:54,180
Anyway, the way to convince a program manager
is to show him good test data.

1203
01:19:54,215 --> 01:20:01,180
During the development, we developed this
process of spraying the walls and not getting

1204
01:20:02,730 --> 01:20:06,630
water carryover which will obviously freeze
up your steam duct.

1205
01:20:06,665 --> 01:20:09,170
Which you don't want.

1206
01:20:09,205 --> 01:20:16,170
But, as the design evolved, we had to get
more sophisticated because we needed this

1207
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.

1208
01:20:23,245 --> 01:20:26,010
And we did that with that 40 to 56 set point.

1209
01:20:26,045 --> 01:20:30,170
And so we needed a small evaporator that could
handle that.

1210
01:20:30,205 --> 01:20:33,290
It was called the "topper." It tops off the
radiator.

1211
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

1212
01:20:37,515 --> 01:20:38,980
a loss of capacity.

1213
01:20:39,015 --> 01:20:43,680
And so the second chamber was the hallowed
chamber.

1214
01:20:43,715 --> 01:20:45,360
Together they do the whole job.

1215
01:20:45,395 --> 01:20:52,320
When the radiators are working only topper,
you can come home with this system functional

1216
01:20:52,355 --> 01:20:54,190
and make it home.

1217
01:20:54,225 --> 01:20:57,830
It turns out we never did freeze up the steam
duct so that part was good.

1218
01:20:57,865 --> 01:21:02,500
It turns out that we had some freezing in
the chamber.

1219
01:21:02,535 --> 01:21:09,500
And, in fact, we had to develop a process
that acknowledged that that could occur.

1220
01:21:11,050 --> 01:21:12,030
And how would we flush it?

1221
01:21:12,065 --> 01:21:15,070
It is called "flushing." And so we did develop
a process.

1222
01:21:15,105 --> 01:21:16,590
And it has never failed.

1223
01:21:16,625 --> 01:21:18,350
The flushing process always works.

1224
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

1225
01:21:23,175 --> 01:21:30,140
times maybe over the Shuttle flights we've
had some freezing inside the cavities.

1226
01:21:31,050 --> 01:21:33,450
There is a non-propulsive overboard vent.

1227
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

1228
01:21:38,135 --> 01:21:41,750
long times during the mission and you might
be pointing or whatever you might be doing.

1229
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

1230
01:21:46,385 --> 01:21:50,580
type duct.

1231
01:21:50,615 --> 01:21:53,400
The ammonia boiler, its heat sink is ammonia.

1232
01:21:53,434 --> 01:21:58,440
As I mentioned before, it evaporates all the
way to the ground where the water won't.

1233
01:21:58,475 --> 01:22:00,270
The redundant boiler is here.

1234
01:22:00,305 --> 01:22:02,450
Up here there are no redundant boilers.

1235
01:22:02,485 --> 01:22:05,059
These two chambers have redundant everything.

1236
01:22:05,095 --> 01:22:10,960
They have redundant feed water systems and
redundant control systems, redundant spray

1237
01:22:10,995 --> 01:22:14,120
nozzles, redundant everything, but the chamber
is a chamber.

1238
01:22:14,155 --> 01:22:14,660
You get what you get.

1239
01:22:14,695 --> 01:22:19,460
They are redundant boilers is the way the
ammonia boiler gets its redundancy.

1240
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.

1241
01:22:26,325 --> 01:22:29,100
It turns out that we don't do that anymore.

1242
01:22:29,135 --> 01:22:35,510
It turns out operationally we learned that
if we cold soak the radiators before we shut

1243
01:22:35,545 --> 01:22:41,559
the doors and then bypass them and come home
on the flash evaporator that there is a lot

1244
01:22:41,595 --> 01:22:43,410
of heat capacity still left in those radiators.

1245
01:22:43,445 --> 01:22:46,950
There is a lot of fluid out there and it is
cold.

1246
01:22:46,985 --> 01:22:53,950
And so we can actually go all the way to wheel
stop on the radiator.

1247
01:22:54,510 --> 01:22:58,340
And so at 175,000 feet we start flowing the
radiator.

1248
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.

1249
01:23:04,684 --> 01:23:11,650
And after wheel stop the ammonia boiler cranks
up.

1250
01:23:12,380 --> 01:23:15,070
I mentioned the Freon 21, the low viscosity.

1251
01:23:15,105 --> 01:23:18,190
We got an excellent performance out of that.

1252
01:23:18,225 --> 01:23:21,790
The low viscosity is really, really important,
as much parallelism as we have.

1253
01:23:21,825 --> 01:23:23,640
I didn't really give you the numbers.

1254
01:23:23,675 --> 01:23:25,690
In the single panels we have 26 tubes.

1255
01:23:25,725 --> 01:23:32,550
In the two-sided panels, I believe, there
are 66 tubes.

1256
01:23:32,585 --> 01:23:33,290
Lots of tubes.

1257
01:23:33,325 --> 01:23:34,230
Lots of parallelism.

1258
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

1259
01:23:41,005 --> 01:23:41,540
loop does great.

1260
01:23:41,575 --> 01:23:48,120
We have redundant pumps, all liquid heat exchangers
and cold plates.

1261
01:23:48,155 --> 01:23:50,330
This is that chamber that I told you.

1262
01:23:50,365 --> 01:23:54,620
If you can look right down here, this is one
person.

1263
01:23:54,655 --> 01:23:57,190
In fact, there is a radiator panel.

1264
01:23:57,225 --> 01:23:59,309
This was during buildup.

1265
01:23:59,345 --> 01:24:04,330
Twice we tested the flash evaporator in this
environment once as part of the integrated

1266
01:24:04,365 --> 01:24:07,990
system with all the radiators and once by
itself.

1267
01:24:08,025 --> 01:24:12,350
And twice we tested the radiators, one as
part of the integrated system and once by

1268
01:24:12,385 --> 01:24:13,010
themselves.

1269
01:24:13,045 --> 01:24:16,490
So we did essentially three large tests.

1270
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

1271
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.

1272
01:24:26,245 --> 01:24:29,480
And it proved that the system could work.

1273
01:24:29,515 --> 01:24:34,559
It also proved that we had to tune the flash
evaporator nozzle because it was wrong.

1274
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.

1275
01:24:38,885 --> 01:24:42,660
A machine out of columbium, somebody else
will have to answer why.

1276
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

1277
01:24:47,765 --> 01:24:48,210
successful.

1278
01:24:48,245 --> 01:24:53,480
[AUDIENCE QUESTION]

1279
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

1280
01:24:57,934 --> 01:24:59,340
chamber.

1281
01:24:59,375 --> 01:25:03,400
And it had a solar and full vacuum.

1282
01:25:03,434 --> 01:25:05,690
[AUDIENCE QUESTION]

1283
01:25:05,725 --> 01:25:07,770
It was a manned chamber then.

1284
01:25:07,805 --> 01:25:09,980
It is not now.

1285
01:25:10,015 --> 01:25:13,870
After Apollo-Soyuz, it hasn't been manned
since then.

1286
01:25:13,905 --> 01:25:16,250
It's still available for testing but is not
manned.

1287
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.

1288
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

1289
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,

1290
01:25:39,420 --> 01:25:46,420
you know, you heard about the budgetary constraints.

1291
01:25:55,850 --> 01:25:56,100
The Shuttle Program never could have afforded
to build something like that.
But luckily a lot of this equipment was built
during Apollo when the money was much more
available.
If you have been keeping count, we're getting
toward the end here.

1292
01:25:59,385 --> 01:26:06,350
I did want to mention, before we left the
main orbiter systems, that there was some

1293
01:26:06,820 --> 01:26:09,990
rotating equipment life testing that we did
for the program.

1294
01:26:10,025 --> 01:26:13,170
The equipment we're talking about here is
the cabin fan, the water gas separators, the

1295
01:26:13,205 --> 01:26:17,340
avionics bay fans, cabin coolant and the vehicle
coolant pumps.

1296
01:26:17,375 --> 01:26:22,260
The life requirement was 100 missions, and
that was calculated by somebody to be 20,000

1297
01:26:22,295 --> 01:26:22,820
hours.

1298
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

1299
01:26:28,934 --> 01:26:29,980
hardware.

1300
01:26:30,015 --> 01:26:34,700
We set up a laboratory to run the equipment.

1301
01:26:34,735 --> 01:26:37,900
It was obviously a low-maintenance lab.

1302
01:26:37,934 --> 01:26:42,960
We collected data and checked in the room
occasionally to see if everything was all

1303
01:26:42,995 --> 01:26:43,680
right.

1304
01:26:43,715 --> 01:26:49,590
It turned out that all the equipment passed
the 20,000 hour requirement.

1305
01:26:49,625 --> 01:26:52,650
We did learn something, though, that some
of that stuff was so noisy.

1306
01:26:52,684 --> 01:26:55,080
Oh, it was noisy.

1307
01:26:55,115 --> 01:27:02,080
There was some work done on some muffling,
but the hardware itself was all good.

1308
01:27:04,540 --> 01:27:05,370
We are at the end.

1309
01:27:05,405 --> 01:27:05,880
Yes.

1310
01:27:05,915 --> 01:27:08,710
Were there noise requirements [AUDIENCE QUESTION]?

1311
01:27:08,745 --> 01:27:12,040
Yes, there was a cabin noise spec.

1312
01:27:12,075 --> 01:27:14,530
And, yes, it had to be met.

1313
01:27:14,565 --> 01:27:16,590
And I don't remember how it was met.

1314
01:27:16,625 --> 01:27:17,870
We put mufflers on some of the equipment.

1315
01:27:17,905 --> 01:27:23,920
Maybe some insulation inside of the ducting,
I'm not sure.

1316
01:27:23,955 --> 01:27:26,830
If we have time, COHEN: I will tell a little
anecdote here.

1317
01:27:26,865 --> 01:27:30,600
I chaired the Change Control Board.

1318
01:27:30,635 --> 01:27:32,740
[NOISE OBSCURES]

1319
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

1320
01:27:40,330 --> 01:27:45,370
it was going to really do a detriment to the
astronauts.

1321
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

1322
01:27:53,910 --> 01:27:59,190
and cabin environment down to the level they
wanted.

1323
01:27:59,225 --> 01:28:00,090
I thought for a moment.

1324
01:28:00,125 --> 01:28:03,260
I go out to California a lot.

1325
01:28:03,295 --> 01:28:08,760
I go out to Rockwell and stay in motels that
are on the Los Angeles freeway.

1326
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

1327
01:28:16,080 --> 01:28:18,490
being able to sleep and having all that noise.

1328
01:28:18,525 --> 01:28:22,980
And the doctor looked at me for a moment and
said, well, you're already deaf.

1329
01:28:23,015 --> 01:28:26,059
And I said what did you say?

1330
01:28:26,095 --> 01:28:30,740
But we did have to make some modifications
of it to actually reduce noise.

1331
01:28:30,775 --> 01:28:32,480
Let me interject one item.

1332
01:28:32,515 --> 01:28:35,220
I think somebody asked the issue about the
IMU.

1333
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.

1334
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

1335
01:28:48,085 --> 01:28:49,910
cooling rather than redesign it.

1336
01:28:49,945 --> 01:28:53,910
But we decided to stick with the IMU that
was air-cooled.

1337
01:28:53,945 --> 01:28:56,540
Whether that was the right decision to make,
I don't know.

1338
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.

1339
01:29:00,135 --> 01:29:02,580
I don't think we've had many problems with
the IMU.

1340
01:29:02,615 --> 01:29:06,920
But that is a little anecdote that I thought
of.

1341
01:29:06,955 --> 01:29:10,130
That's a program manager's trait.

1342
01:29:10,165 --> 01:29:14,550
Probably the air-cooled IMU was a less expensive
option.

1343
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.

1344
01:29:21,840 --> 01:29:26,670
And power was available so it was a good tradeoff.

1345
01:29:26,705 --> 01:29:31,400
This is the last of the subsystem areas.

1346
01:29:31,434 --> 01:29:33,850
This is the EVA airlock support.

1347
01:29:33,885 --> 01:29:38,590
The Environmental Thermal Control and Life
Support System does support the airlock.

1348
01:29:38,625 --> 01:29:45,590
It maintains the cabin pressure and composition
during the airlock repress and depress.

1349
01:29:45,870 --> 01:29:52,870
This is really a requirement back on the ARS
and the pressure and composition control system

1350
01:29:53,130 --> 01:29:58,930
because airlock use basically dumps cabin
gas and then you repress the airlock.

1351
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.

1352
01:30:04,945 --> 01:30:08,570
We also provide the service and cooling umbilical.

1353
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

1354
01:30:12,645 --> 01:30:18,040
with cooling and oxygen through an umbilical
so they don't use the consumables in their

1355
01:30:18,075 --> 01:30:20,140
spacesuit.

1356
01:30:20,175 --> 01:30:23,970
And so that is provided by the ETCLSS.

1357
01:30:24,005 --> 01:30:27,590
Heat rejection, the crew wears a liquid cooling
garment.

1358
01:30:27,625 --> 01:30:33,360
And the cooling for that is done by the vehicle
until you go EVA, of course.

1359
01:30:33,395 --> 01:30:33,950
Then the recharge.

1360
01:30:33,985 --> 01:30:39,930
We supply the backpack O2 recharge from the
900 PSI cryo.

1361
01:30:39,965 --> 01:30:42,590
We supply the water to recharge for the sublimator.

1362
01:30:42,625 --> 01:30:49,360
NASA is overrun with acronyms.

1363
01:30:49,395 --> 01:30:54,340
EMU is extra vehicular mobility unit, which
means nothing but spacesuit and backpack.

1364
01:30:54,375 --> 01:30:58,570
So the spacesuit and backpack uses an evaporative
heat sink and it uses a sublimator.

1365
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

1366
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

1367
01:31:12,115 --> 01:31:12,540
flashing it.

1368
01:31:12,575 --> 01:31:16,110
Anyway, that has to be serviced.

1369
01:31:16,145 --> 01:31:18,890
That water is provided from the system.

1370
01:31:18,925 --> 01:31:22,650
And then the condensate that the crew brings
back, EVA, that's a sweaty job.

1371
01:31:22,684 --> 01:31:25,190
That condensate goes back into the system.

1372
01:31:25,225 --> 01:31:31,920
So the airlock support is another part of
this system.

1373
01:31:31,955 --> 01:31:33,440
In fact, that is the sixth part.

1374
01:31:33,475 --> 01:31:34,940
So we are through.

1375
01:31:34,975 --> 01:31:37,630
This is a picture of the airlock.

1376
01:31:37,665 --> 01:31:38,340
Not really the airlock.

1377
01:31:38,375 --> 01:31:42,550
This is the test chamber that we built to
put the equipment in.

1378
01:31:42,585 --> 01:31:46,390
You'll notice it has the right hatch in it.

1379
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

1380
01:31:51,585 --> 01:31:56,920
was this hatch basically on the backside of
the test chamber.

1381
01:31:56,955 --> 01:31:58,450
We hook those together.

1382
01:31:58,485 --> 01:32:03,200
Because, as I said, as you depress and repress
the airlock it affects the cabin.

1383
01:32:03,235 --> 01:32:06,770
So we needed a test environment that had both
those simultaneously.

1384
01:32:06,805 --> 01:32:10,570
But the difference is this has to go all the
way to vacuum.

1385
01:32:10,605 --> 01:32:14,070
So we connected this to our vacuum system.

1386
01:32:14,105 --> 01:32:18,790
And, when the crew is inside this, it is a
manned vacuum test.

1387
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,

1388
01:32:26,870 --> 01:32:30,450
8 PSI would be the lowest it would ever be.

1389
01:32:30,485 --> 01:32:36,700
And I think the last picture is a spacesuit
inside the airlock.

1390
01:32:36,735 --> 01:32:40,860
And this is just a little cutaway showing
the airlock.

1391
01:32:40,895 --> 01:32:43,540
This was mounted on the back of that chamber
you saw earlier.

1392
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

1393
01:32:56,880 --> 01:32:58,580
will have some questions.

1394
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

1395
01:33:07,870 --> 01:33:14,870
or her spacesuit into that EVA test chamber,
into the airlock test chamber so you actually

1396
01:33:15,040 --> 01:33:19,960
get a chance to take your own suit down to
vacuum.

1397
01:33:19,995 --> 01:33:26,920
And particularly, before you do your very
first EVA, it is really a confidence builder

1398
01:33:26,955 --> 01:33:32,480
because the physical sensations that you get
in a suit -- And remember you're at about

1399
01:33:32,515 --> 01:33:35,990
a 4 PSI pure oxygen environment.

1400
01:33:36,025 --> 01:33:39,090
Your body, the inside of your mouth feels
a little different.

1401
01:33:39,125 --> 01:33:44,740
There are funny sounds with the fans inside
the suit.

1402
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

1403
01:33:48,785 --> 01:33:50,950
go outside into space.

1404
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,

1405
01:33:58,480 --> 01:34:01,410
you are supported because of the weight of
the suit.

1406
01:34:01,445 --> 01:34:04,580
It doesn't look like there is anybody in this
suit.

1407
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

1408
01:34:11,295 --> 01:34:13,940
chamber which is on quick release bolts.

1409
01:34:13,975 --> 01:34:18,760
You're suspended up here.

1410
01:34:18,795 --> 01:34:25,760
And, if you ever have a problem, they can
release this, repressurize the chamber within

1411
01:34:27,480 --> 01:34:29,270
about 30 seconds.

1412
01:34:29,305 --> 01:34:32,790
I think that's the limit for a manned rated
chamber.

1413
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

1414
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.

1415
01:34:43,115 --> 01:34:47,210
This is just an inverted bell jar.

1416
01:34:47,245 --> 01:34:49,530
The hatch is not sealed.

1417
01:34:49,565 --> 01:34:56,530
When you depress it just like pulls it out
and seals due to the pressure difference.

1418
01:34:56,670 --> 01:34:59,600
You just lift the top off.

1419
01:34:59,635 --> 01:35:06,480
Yet another example of the extensive testing
that we go through before every mission.

1420
01:35:06,514 --> 01:35:13,480
I might add one more thing, which I forgot
actually to add earlier.

1421
01:35:14,790 --> 01:35:21,790
The manned rating is a term used in manned
spacecraft which means that you've specifically

1422
01:35:23,139 --> 01:35:30,139
tested it and said that its design is worthy
of supporting a human.

1423
01:35:31,440 --> 01:35:34,809
The airlock had to provide that function.

1424
01:35:34,844 --> 01:35:37,330
So Aaron was faced with man rating the airlock.

1425
01:35:37,365 --> 01:35:42,610
And manned test capability is very scarce.

1426
01:35:42,645 --> 01:35:48,400
In fact, JSC may be the only place anymore
that can do it.

1427
01:35:48,434 --> 01:35:54,059
Anyway, we volunteered to do that as part
of our test program as a programmatic requirement.

1428
01:35:54,094 --> 01:36:00,559
Not as testing or watching or confirming anything,
but as a prime part of the test program was

1429
01:36:00,594 --> 01:36:01,510
the manned rating of the airlock.

1430
01:36:01,545 --> 01:36:02,730
And that was done in Houston.

1431
01:36:02,764 --> 01:36:05,969
That is an interesting thought.

1432
01:36:06,005 --> 01:36:12,969
If my memory serves me correctly, one of the
problems we had in the early part of the Manned

1433
01:36:14,500 --> 01:36:21,500
Space Program was doing some chamber runs
McDonnell-Douglas with a two-gas system where

1434
01:36:23,770 --> 01:36:28,860
we actually lost the heat [NOISE OBSCURES]

1435
01:36:28,895 --> 01:36:32,990
in the chamber and almost lost a test subject.

1436
01:36:33,025 --> 01:36:37,840
And that was when Apollo decided to go to
100% oxygen.

1437
01:36:37,875 --> 01:36:38,880
And that is what led up to the fire on the
pad.

1438
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

1439
01:36:38,880 --> 01:36:39,130
reason.
And that is really if you can realize that
100% oxygen at 16 PSI everything burns.

1440
01:36:45,635 --> 01:36:45,870
Stainless steel is not self-extinguishing
at 16 PSI.

1441
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.

1442
01:36:47,285 --> 01:36:49,050
It was a function of doing some test work
with the combined atmosphere.

1443
01:36:49,085 --> 01:36:54,889
So you have got to be careful that sometimes
you don't over-react the thing.

1444
01:36:54,925 --> 01:37:01,889
Then we went back to a different type of atmosphere.

1445
01:37:15,030 --> 01:37:18,200
Did you have a question?

1446
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

1447
01:37:22,585 --> 01:37:23,830
other systems.

1448
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

1449
01:37:34,610 --> 01:37:35,840
you wanted?

1450
01:37:35,875 --> 01:37:39,290
That is a good question but you're asking
the wrong person.

1451
01:37:39,325 --> 01:37:41,719
We are the government.

1452
01:37:41,755 --> 01:37:45,719
We hired a contractor to design the vehicle.

1453
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,

1454
01:37:52,655 --> 01:37:55,840
very integral with.

1455
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

1456
01:38:00,445 --> 01:38:02,710
plate here and put that heat exchanger there.

1457
01:38:02,745 --> 01:38:05,020
The vehicle integrated design was Rockwell's.

1458
01:38:05,055 --> 01:38:07,130
Let me tell you how it was done.

1459
01:38:07,165 --> 01:38:09,940
Actually, in those years we didn't have CAD/CAM
systems.

1460
01:38:09,975 --> 01:38:14,250
What we did is used everything on mockups.

1461
01:38:14,285 --> 01:38:16,320
We did mockups.

1462
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

1463
01:38:21,155 --> 01:38:21,370
plumbing.

1464
01:38:21,260 --> 01:38:23,590
And this was all laid out on a mockup.

1465
01:38:23,625 --> 01:38:28,210
And basically that was how it was negotiated
in terms of what you need.

1466
01:38:28,245 --> 01:38:32,020
In today's environment you wouldn't do that.

1467
01:38:32,055 --> 01:38:34,170
You would use electronic capability.

1468
01:38:34,205 --> 01:38:36,300
You would use your CAD/CAM systems.

1469
01:38:36,335 --> 01:38:37,860
You would actually draw it up on your computer.

1470
01:38:37,895 --> 01:38:40,440
In fact, the 777 was built that way.

1471
01:38:40,475 --> 01:38:44,590
The 777 at Boeing, they didn't use hard mockups.

1472
01:38:44,625 --> 01:38:46,639
They used electronic mockups.

1473
01:38:46,675 --> 01:38:47,719
And that is what we would do today.

1474
01:38:47,755 --> 01:38:48,969
And it would be much easier.

1475
01:38:49,005 --> 01:38:50,809
You would probably call all the engineers
together.

1476
01:38:50,844 --> 01:38:55,410
You would sit down and show how the equipment
was laid out, get a satisfactory buyoff on

1477
01:38:55,445 --> 01:38:58,600
it and do it much more rapidly and much more
quickly.

1478
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

1479
01:39:04,395 --> 01:39:07,670
negotiate the space you need for it.

1480
01:39:07,705 --> 01:39:09,530
That is a good question.

1481
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

1482
01:39:15,745 --> 01:39:17,360
in a soft mockup or hard mockup.

1483
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

1484
01:39:20,325 --> 01:39:23,080
is how it is going to look and then get a
buyoff on it.

1485
01:39:23,115 --> 01:39:24,650
Today you wouldn't do it that way.

1486
01:39:24,684 --> 01:39:27,550
You would do it all electronically so it would
change.

1487
01:39:27,585 --> 01:39:29,490
Well, let me ask you a question.

1488
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

1489
01:39:35,465 --> 01:39:36,600
to fly or during the flight?

1490
01:39:36,635 --> 01:39:43,600
What did you have the biggest concern about?

1491
01:39:47,210 --> 01:39:48,660
I was young and confident.

1492
01:39:48,695 --> 01:39:54,530
I don't know that I had a specific area that
I was really concerned about.

1493
01:39:54,565 --> 01:39:56,040
Like these people right here, right?

1494
01:39:56,075 --> 01:39:57,540
Young and confident.

1495
01:39:57,575 --> 01:40:03,630
I did recognize, though, but it did result
in the integrated tests that I showed.

1496
01:40:03,665 --> 01:40:09,300
I did recognize that we had the most highly
integrated thermal control system ever conceived.

1497
01:40:09,335 --> 01:40:12,840
And it had, as I said, modes within modes.

1498
01:40:12,875 --> 01:40:15,860
It changed modes with respect to the vehicle
phases.

1499
01:40:15,895 --> 01:40:19,690
It changed modes with respect to operation.

1500
01:40:19,725 --> 01:40:22,820
We had 9 PSI that went to 10.2 PSI.

1501
01:40:22,855 --> 01:40:23,590
We had 8 PSI.

1502
01:40:23,625 --> 01:40:29,440
We had thermal control loops, ammonia boilers,
flash evaporators, so I did recognize the

1503
01:40:29,475 --> 01:40:30,380
sophistication.

1504
01:40:30,415 --> 01:40:37,380
In fact, we proposed early on to use that
large chamber in an integrated vehicle test.

1505
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.

1506
01:40:49,380 --> 01:40:51,130
And that was viewed to be impractical.

1507
01:40:51,165 --> 01:40:53,380
It was cut it off at the bulkhead.

1508
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

1509
01:40:58,065 --> 01:40:58,760
be impractical.

1510
01:40:58,795 --> 01:41:02,130
But it still was a very integrated design.

1511
01:41:02,165 --> 01:41:08,139
All the systems engineering that was there
created that inner-dependency.

1512
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.

1513
01:41:13,275 --> 01:41:20,240
Remember in the very beginning of this I talked
about ownership of all the technical aspects?

1514
01:41:23,940 --> 01:41:25,450
We had ownership.

1515
01:41:25,485 --> 01:41:32,450
We believed that what we had done was prudent,
appropriate, and we believed it would work.

1516
01:41:32,950 --> 01:41:35,010
It wasn't like you bought something and you
hope it works.

1517
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

1518
01:41:39,775 --> 01:41:40,250
CEV?

1519
01:41:40,285 --> 01:41:44,219
Do you think it's going to have a very similar
type system or have you thought about that?

1520
01:41:44,255 --> 01:41:45,190
Well, we hope so.

1521
01:41:45,225 --> 01:41:52,190
Our new administrator has sort of back to
the grassroots philosophy, or at least right

1522
01:41:52,969 --> 01:41:53,860
now.

1523
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

1524
01:42:00,315 --> 01:42:04,570
the government will have ownership again of
the technical aspects of the design.

1525
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

1526
01:42:13,080 --> 01:42:16,540
free-thinking and the independence that the
government can bring to that, there is another

1527
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

1528
01:42:20,665 --> 01:42:21,840
their thing.

1529
01:42:21,875 --> 01:42:26,719
And, obviously, you wouldn't get that position
from me but there are people that believe

1530
01:42:26,755 --> 01:42:27,420
that's the right way to do it.

1531
01:42:27,455 --> 01:42:33,150
Do you think the system will look pretty much
like this or similar to it?

1532
01:42:33,184 --> 01:42:37,630
Well, similar, yes, I do think so.

1533
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

1534
01:42:46,050 --> 01:42:49,420
on the program manager to go with the tried
and true.

1535
01:42:49,455 --> 01:42:53,840
So I don't think there is going to be innovation
that has risk with it.

1536
01:42:53,875 --> 01:42:58,490
Maybe there will be innovation that is good
engineering, but I think the innovation with

1537
01:42:58,525 --> 01:43:00,700
risk will be very much minimized.

1538
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

1539
01:43:05,725 --> 01:43:06,380
vehicle finished.

1540
01:43:06,415 --> 01:43:13,380
I think that is going to breed some conservatism
on the design side.

1541
01:43:17,660 --> 01:43:24,660
We talk about considering operation while
you're doing the design, but there were always

1542
01:43:31,030 --> 01:43:32,660
things once the design was made.

1543
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

1544
01:43:38,625 --> 01:43:39,350
workarounds.

1545
01:43:39,385 --> 01:43:44,219
And one of the other things that after the
system is designed, we then start to figure

1546
01:43:44,255 --> 01:43:48,210
out how can it fail and work on malfunction
procedures.

1547
01:43:48,245 --> 01:43:54,440
And I know that the malfunction procedure
for loss of two coolant loops that was probably

1548
01:43:54,475 --> 01:43:57,639
the worst simulation case that we ever had
to deal with.

1549
01:43:57,675 --> 01:44:01,930
I am curious to get your opinion.

1550
01:44:01,965 --> 01:44:08,780
Walt described how we have two independent
cooling loops so that in principle one failure

1551
01:44:08,815 --> 01:44:09,889
won't take them both out.

1552
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

1553
01:44:14,514 --> 01:44:20,000
in there which I think was corrected but where
you could have lost both of the cooling loops

1554
01:44:20,035 --> 01:44:23,780
with a single failure.

1555
01:44:23,815 --> 01:44:26,889
The only failure I remember is one that John
Young used to worry about.

1556
01:44:26,925 --> 01:44:33,889
It had to do with if you did lose a radiator
that that could bleed your accumulator down.

1557
01:44:34,170 --> 01:44:40,280
And so they did add an isolation valve so
they can isolate the radiator side.

1558
01:44:40,315 --> 01:44:45,830
But the idea was to obviously not lose your
fluid with a single hit.

1559
01:44:45,865 --> 01:44:50,170
That even though you have a nice completely
functional thermal control system it is useless

1560
01:44:50,205 --> 01:44:52,370
because it has no fluid.

1561
01:44:52,405 --> 01:44:58,650
We did have an emergency de-orbit procedure
for loss of two Freon cooling loops.

1562
01:44:58,684 --> 01:45:03,389
And, of all the things that we practices,
that was the hairiest because it was absolutely

1563
01:45:03,425 --> 01:45:04,559
time critical.

1564
01:45:04,594 --> 01:45:09,480
At this point, you have no way of getting
heat out of the cabin so you cannot ultimately

1565
01:45:09,514 --> 01:45:11,520
cool your electronics.

1566
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.

1567
01:45:17,434 --> 01:45:21,460
Hopefully you're within range of a landing
site.

1568
01:45:21,495 --> 01:45:27,780
And then you turn off all the equipment that
you can possibly turn off, including most

1569
01:45:27,815 --> 01:45:28,660
of your computers.

1570
01:45:28,695 --> 01:45:35,660
And, when you're riding down through entry,
you basically watch the temperature of the

1571
01:45:35,990 --> 01:45:36,240
computer.
And, as each computer would get up to its
failure temperature, you would then switch

1572
01:45:42,065 --> 01:45:47,940
on the next computer, transfer the data, you
know, turn off the computer which has just

1573
01:45:47,975 --> 01:45:52,250
about failed, and hopefully you could make
it to the ground.

1574
01:45:52,285 --> 01:45:59,250
And I know the instructors that would lead
us through this exercise said that the information

1575
01:45:59,350 --> 01:46:03,930
they had gotten from the thermal analyst was
that nobody was really sure whether we could

1576
01:46:03,965 --> 01:46:04,340
make it.

1577
01:46:04,375 --> 01:46:06,889
I don't know what your opinion was or not.

1578
01:46:06,925 --> 01:46:07,680
We practiced it.

1579
01:46:07,715 --> 01:46:11,940
But obviously, I think I've told you, nobody
has ever died in a simulator.

1580
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

1581
01:46:18,565 --> 01:46:23,450
to duplicate the way the Shuttle is going
to behave in an absolute emergency situation

1582
01:46:23,485 --> 01:46:24,690
like that.

1583
01:46:24,725 --> 01:46:28,420
We survived in the simulator but I don't know
what your feeling is.

1584
01:46:28,455 --> 01:46:32,670
Well, we do address the thermal model accuracy.

1585
01:46:32,705 --> 01:46:38,190
We do specific testing to validate the thermal
model so we do have pretty good confidence

1586
01:46:38,225 --> 01:46:38,580
in those.

1587
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

1588
01:46:43,985 --> 01:46:45,040
an overheat situation?

1589
01:46:45,075 --> 01:46:46,430
I mean there is no magic number.

1590
01:46:46,465 --> 01:46:51,860
It is not like at 143 degrees it is OK and
144 it is not OK.

1591
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.

1592
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

1593
01:47:02,605 --> 01:47:04,260
and come home.

1594
01:47:04,295 --> 01:47:05,040
Yes.

1595
01:47:05,075 --> 01:47:08,360
You talked earlier a little about oxygen and
nitrogen mixing in the cabin.

1596
01:47:08,395 --> 01:47:11,969
I was wondering if there is a way to really
study that on the ground since you're not

1597
01:47:12,005 --> 01:47:13,880
in a DoD environment.

1598
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

1599
01:47:18,815 --> 01:47:19,960
his heat into?

1600
01:47:19,995 --> 01:47:20,760
Very good.

1601
01:47:20,795 --> 01:47:22,210
I just forgot to mention that earlier.

1602
01:47:22,245 --> 01:47:29,210
The testing that we ran, we had to set it
up very carefully.

1603
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

1604
01:48:00,555 --> 01:48:01,750
to mix that stuff for you.

1605
01:48:01,785 --> 01:48:07,389
What we did is set up a thermal condition
where less than one degree thermal gradient

1606
01:48:07,425 --> 01:48:10,570
everywhere in there had to exist before we
ran the test.

1607
01:48:10,605 --> 01:48:17,440
And that was to guaranty that we had no help
from the naturally induced circulation.

1608
01:48:17,475 --> 01:48:18,900
But you are absolutely right.

1609
01:48:18,934 --> 01:48:24,139
That test would have been a useless test without
neutralizing the gravity effects.

1610
01:48:24,175 --> 01:48:31,139
And actually the first time that I did the
spacesuit test in there we actually used the

1611
01:48:32,660 --> 01:48:33,280
10.2 protocol.

1612
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

1613
01:48:42,110 --> 01:48:45,040
then we could do just a 40 minute prebreathe.

1614
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

1615
01:48:53,020 --> 01:48:56,790
of staying through the night, you go in early
in the morning.

1616
01:48:56,825 --> 01:49:00,900
And then you're coming right from a sea level
environment.

1617
01:49:00,934 --> 01:49:07,900
So, before you go down to 4 PSI in the suit,
you actually have to prebreathe pure oxygen

1618
01:49:07,950 --> 01:49:09,200
for four hours.

1619
01:49:09,235 --> 01:49:11,040
As Walt said, that was the alternative.

1620
01:49:11,075 --> 01:49:15,540
You basically just get in your suit.

1621
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

1622
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

1623
01:49:25,184 --> 01:49:26,920
a little black and white TV monitor.

1624
01:49:26,955 --> 01:49:31,350
And you just sort of sit there for four hours.

1625
01:49:31,385 --> 01:49:36,100
And the problem is you're not allowed to go
to sleep.

1626
01:49:36,135 --> 01:49:40,059
That would be the easiest thing, but they
want you actually to move around because when

1627
01:49:40,094 --> 01:49:44,590
you're moving your muscles you're actually
then doing a better job of de-nitrogenating.

1628
01:49:44,625 --> 01:49:45,710
So you have to stay awake.

1629
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

1630
01:49:52,415 --> 01:49:55,360
in and say, Jeff, are you awake?

1631
01:49:55,395 --> 01:49:58,760
But this was a very, very useful facility.

1632
01:49:58,795 --> 01:50:01,590
I mean they used it for all different sorts
of things.

1633
01:50:01,625 --> 01:50:07,550
And I guess that was the one new facility
which was built for the Shuttle specifically.

1634
01:50:07,585 --> 01:50:07,800
Yes.

1635
01:50:07,550 --> 01:50:12,950
Jeff mentioned several times the 10.2 and
I talked about the 9.

1636
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

1637
01:50:21,460 --> 01:50:23,130
got too high.

1638
01:50:23,165 --> 01:50:26,550
And so there was much concern about flammability.

1639
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

1640
01:50:33,910 --> 01:50:35,630
a flammability issue.

1641
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.

1642
01:50:44,380 --> 01:50:50,160
If you're in the bends while diving, somebody
mentioned diving earlier, scuba, you could

1643
01:50:50,195 --> 01:50:51,139
usually use a two to one.

1644
01:50:51,175 --> 01:50:55,330
If you don't reduce pressure more than half
you're probably OK.

1645
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.

1646
01:50:58,375 --> 01:51:01,260
And the suit is at 4, so there was that issue
again.

1647
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

1648
01:51:08,340 --> 01:51:12,130
and developed the prebreathe protocols that
made that acceptable.

1649
01:51:12,165 --> 01:51:13,430
That is sort of how it balanced out.

1650
01:51:13,465 --> 01:51:15,200
That was another operational move later.

1651
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

1652
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

1653
01:51:25,215 --> 01:51:30,430
do a bunch of tests and check out communication
tests and cooling tests.

1654
01:51:30,465 --> 01:51:36,400
You basically are not losing much time by
having to spend 40 minutes prebreathing.

1655
01:51:36,434 --> 01:51:38,070
The whole thing worked out pretty well.

1656
01:51:38,105 --> 01:51:43,469
And it will be an interesting question on
how they designed the CEV because the CEV

1657
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.

1658
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

1659
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

1660
01:52:00,075 --> 01:52:07,040
or 9 PSI so that you can go right into a spacesuit
without an extensive prebreathe.

1661
01:52:08,740 --> 01:52:12,450
And, of course, people are always trying to
figure out could we design the spacesuit to

1662
01:52:12,485 --> 01:52:14,110
work at a higher pressure?

1663
01:52:14,145 --> 01:52:17,130
But then you give up maneuverability.

1664
01:52:17,165 --> 01:52:23,670
We will talk about that in another lecture
that I will be giving on EVA systems.

1665
01:52:23,705 --> 01:52:24,340
Walt, thank you very much.

1666
01:52:24,375 --> 01:52:25,050
I enjoyed it.

1667
01:52:25,085 --> 01:52:25,300
[APPLAUSE]