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There were a couple of areas that have been
discussed a little bit, which I wanted to

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elaborate on because I think it is significant.

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One of them relates to intact aborts.

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The question of a crew escape system and whether
that should be automated, whether the crew

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should have control and what is required if
you actually have the crew take control.

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I think Chris Kraft gave an interesting perspective
with the idea that because of the difficulties,

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or given the requirements, really, the impossibility
of incorporating a capsule escape system for

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the Shuttle, the project basically took the
point of view that the Shuttle itself was

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the escape pod, which means that you have
to recover the Shuttle intact regardless of

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any engine failures.

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Now that, of course, requires 100% reliability
of the solid rocket boosters which we never

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did achieve with Challenger.

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Although, of course, had we operated it within
its spec limits it might be another story.

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But, in any case, I want to go through some
of the details of a return to launch site

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abort and then I will describe an incident
which occurred on our last flight to give

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you an idea of what is involved in the actual
operation of abort modes.

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The idea is you have the two solid rocket
boosters which have to light.

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And they are going to perform no matter what.

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If one of those boosters doesn't light and
the other does it is a bad day.

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What can you say?

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And, obviously, if one of them fails during
flight it is a bad day.

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And, which was more of a design problem, if
they don't tail off at just the identical

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rate so that you get asymmetric thrust greater
than a certain capability of the Shuttle to

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control, you have had a bad day.

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And because of the requirement to have symmetric
thrust, I don't think if this was discussed

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before, when the solid rocket boosters are
poured, they mix a batch of propellant sort

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of like you mix bread dough.

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And then they pour the propellant into both
the left and the right booster segments at

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the same time so each booster segment has
the identical batch of propellant in it.

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It may not be the same from the bottom to
the top, but it is the same from the left

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to the right.

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And that is critical.

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And then they always reserve a certain proportion
of the propellant.

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And they do tests on that to make sure that
there are no process control problems.

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OK.

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You still need the three main engines to have
enough thrust.

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The boosters each give you about 2.5 million
pounds thrust, so that is about five million

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pounds to get off the ground.

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These give you about a half a million pound
thrust at vacuum, four hundred and some odd

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thousand pounds thrust, so still over a million
pounds thrust.

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And, of course, the problem you have during
first stage is you have big gravity losses.

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The Shuttle on the pad weighs about 5.5 million
pounds with all the propellant.

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If you don't fire your main engines you are
barely going to lift off the ground.

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Actually, I guess it is a little bit less
than five million pounds.

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But, in any case, without the three main engines
firing you don't have enough thrust to get

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into orbit.

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Now, remember we talked about for deorbit
burn, normally we fire both OMS engines.

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If one of the OMS engines is out you can fire
one engine for twice as long.

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Or, if they are both out, you can fire the
four RCS thrusters for twice as long again.

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Because you are in orbit, you are weightless,
you don't have gravity losses, so firing half

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as many engines for twice as long is completely
equivalent.

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When you are taking off against gravity that
is not true.

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I mean if you only have five million pounds
of thrust for a five million pound payload

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you are just going to sit on the pad and burn
all your fuel.

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OK.

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You need your three engines.

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And, in fact, another interesting point, the
attachment between the external tank and the

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Shuttle, that is stressed to assume that you
have at least one engine burning.

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They tell me that if the Shuttle took off
with just the solid boosters and you didn't

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have any thrust, sort of keeping the Shuttle
up with the external tank, that the structural

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attachment points would fail.

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Anyway, you need your engines.

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What happens if you lose an engine early on?

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If you are far enough into the launch, you
are over the main gravity loss segment usually

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starting at about 3.5 to 4 minutes into launch.

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If you lose one engine you can make it over
the ocean, And that is called a Trans-Atlantic

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Abort.

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And, when you do that, you are basically flying
upside down.

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You will do a roll maneuver, drop your external
tank and come in and land.

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And you are basically going in the same direction
which is nice when you are flying a rocket.

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These things are hard to turn around.

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But if you are going to do a return to launch
site abort that is exactly what you have to

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do.

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So, this is a procedure that has been analyzed
to death in many, many computer simulations.

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The basic procedure is you take off and you
lose an engine.

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Now, it doesn't matter when you lose an engine
in the first 2.5 minutes.

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You don't do anything while the solid rocket
boosters are firing.

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They basically have open loop guidance.

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There is a certain projector programmed in
and you cannot readjust that trajectory with

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a closed loop guidance solution to accommodate
for any sort of a malfunction.

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So, you don't even declare an RTLS abort.

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And that, by the way, is done by the crew
punching a button which essentially is a protected

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button.

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You punch that.

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And you can also do it via a computer input
if something goes wrong with the button.

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You declare an RTLS abort after SRB separation.

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Immediately what happens is your trajectory
increases because you want to gain altitude,

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and you will see why in a minute.

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But what happens now is you've got a pretty
hefty downrange velocity already and you have

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got to turn around and come back.

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You have also got to worry about the disposal
of your external tank.

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If you turn around and you come back, you
are still burning your engines, you are still

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riding your tank, and you don't want the tank
coming down on Melbourne or Disney World or

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anything like that.

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The basic procedure is as follows.

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You are going out, you loft your trajectory
a bit, once you get far enough out now what

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you do is you do a powered pitch around.

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A very sporty maneuver.

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The external tank is here.

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Now you are flying backwards into your plume
and everybody has speculated on what that

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would actually look like.

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Now you are flying backwards decelerating.

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And, as you decelerate, of course, gravity
is starting to push you down so you've got

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to increase your pitch velocity until finally
you basically have no more horizontal velocity

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and are just sitting statically on top of
your exhaust.

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And now you gradually pitch forward and you
start to fly back.

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Again, you have got to plan your trajectory
so that when you drop the tank it is going

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to come down in the ocean.

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And then, if all that goes well, now you enter
the heading alignment circle.

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And, of course, you are a heavy weight vehicle
because you also, in the process of the RTLS,

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dump your OMS tanks and your RCS propellant
so that you want to make sure you are as light

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as possible.

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Plus, in case you have any problem with landing
you don't want your hypergolic propellant

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tanks to rupture.

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If all that goes well, now you enter the heading
alignment circle and you have hopefully a

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nominal landing.

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As I say, this has been analyzed in high-fidelity
dynamic simulations.

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The crew practices it over and over again.

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Everybody knows the procedures.

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Nobody wants to be the first crew to try this
out.

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Before STS-1, you remember we talked about
how there were lots of problems with the tiles

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falling off.

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I remember one of the people very high up
in NASA, I don't remember if it was the administrator

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or one of the deputies, suggested that maybe
the safest thing to do would be to do a planned

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RTLS because an RTLS, of course, you don't
get up to those high velocities.

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And so you don't have any thermal problems.

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And so if a whole bunch of tiles had fallen
off on the launch pad you could safely do

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an RTLS.

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Well, obviously, they did not appreciate the
difficulties of doing an RTLS and that suggestion

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was not taken up.

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We basically decided we were not going to
fly until we had confidence that the tiles

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were going to stay on.

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Cut forward to February of 1996, which was
my fifth and final Shuttle flight.

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I was the second flight engineer so I was
sitting right behind the pilot who is responsible

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for the main engine performance.

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Now, I should tell you, we have had, in the
course of the 114 Shuttle flights we have

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had four pad shutdowns, pad aborts.

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And I think we talked about that briefly.

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The main engines turn on six seconds before
the solids.

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Just reviewing that does two things.

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It gives the engines time to come up to full
thrust and then you can perform checks on

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them to make sure that they are operating
properly before you commit yourself to flight.

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And, of course, it gives time, because of
the asymmetric thrust, for what we call the

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"twang" that the whole Shuttle stack goes
forward and then back.

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And then, when you get to the vertical, you
light the boosters.

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In fact, when they had the first test firing
on the pad before STS-1, one of the reasons

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that they wanted to do that, in addition to
just confirming that everything was working

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right, is they really wanted precise timing
on the twang.

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People had calculated it, but that is not
something you want to get wrong.

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So, they wanted an experimental verification.

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Of the four pad shutdowns, two of them were
caused by instrumentation and two of them

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were real engine problems.

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I remember the first one was the last flight
before what would have been my first flight

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back in 1984.

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And the main engine cutoff is called MECO.

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So, 8.5 minutes into the flight.

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After they had a pad abort the flight engineer
called to Mission Control we have MECO, somehow

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I thought we would be a little bit higher.

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And, of course, when that happens now you've
got to pull all the engines out, take them

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back to the shop, bring in new engines and
it is about a two or three week stand down.

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And the crew has to go back to Houston.

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And, of course, all of your friends and family
are there and they have to go home.

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It is no fun.

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I mean nobody complains if it is safe.

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We're sitting on the pad, we're counting down
and everything was on schedule.

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In fact, the first of my five flights it had
zero problems, zero delays.

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We were going on the day that was predicted
on the time.

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Countdown to six seconds.

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You can feel the engines.

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Everything starts to rumble.

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The engines start up.

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There is what we call a steam gage, a vertical
bar which shows the engine power.

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Center and right engines come up to 100%.

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The left engine comes up to 40%.

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The pilot calls out left engine at 40%.

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In times like this, your mind is working pretty
fast.

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I remember thinking to myself oh, damn, we
are going to have a pad shutdown, we have

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got to go back to Houston and back to the
simulators.

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I mean stupid things to be thinking about
at that time, but that is sort of the way

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it works.

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And all of a sudden kaboom.

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I feel this big kick in my back.

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The solids have lit.

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What in the hell is going on?

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We were supposed to have a pad abort.

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Now we are going with an engine.

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And, actually, when you are going through
maximum dynamic pressure, max q, the engines

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throttle down to about 65%.

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And there is a malfunction if one of your
engines gets stuck it is called getting stuck

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in the thrust bucket.

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If it doesn't come back to full power you
are RTLS abort.

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Well, we were taking off with one engine at
40%.

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It sort of dawned on me that we were going
to be the first crew to do an RTLS, so at

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that point I start going through my checklists.

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And the pilot calls to the ground we have
ignition, left engine at 40%.

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And so, for about the first 15 seconds or
so, I just had barely time to get out the

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RTLS checklist and start getting ready to
read the procedures.

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And then it turns out that the ground has
more insight than the crew does.

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And it turns out that there are several sensors,
one of which feeds that gauge.

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But, in fact, that sensor had gone bad.

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And, in fact, the left engine was performing
nominally and the ground was able to confirm

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that both by the other sensors and by looking
at the acceleration.

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And so, everything was OK, I put away the
checklist and enjoyed the ride.

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But, first of all, it was kind of a scary
situation.

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But it also shows the difficulty.

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Now, suppose we, as the crew, had been responsible
for declaring an abort.

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If you are going to build in a system where
this is the crew's responsibility then you

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better design your instrumentation so that
the crew has all the instrumentation required

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to make that decision correctly.

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00:17:01,059 --> 00:17:08,059
Similarly, if this were to be an automatic
abort, you've got to have failure detection,

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identification, reconfiguration.

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00:17:17,109 --> 00:17:24,050
The last thing you want is to go into an abort
situation when you don't have to because there

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is no way that an abort is going to be anywhere
near as safe as a nominal mission.

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Obviously, it's just a good story now.

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00:17:40,740 --> 00:17:47,740
But I think it does have something to inform
about how you are going to have to design

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abort systems.

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00:17:49,840 --> 00:17:56,840
And, as both Aaron Cohen and Chris Kraft said,
although the astronauts always felt comfortable

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00:17:59,440 --> 00:18:04,340
with their abort system but I am not sure
that all the people in Mission Control were

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00:18:04,340 --> 00:18:08,510
quite so comfortable knowing the things that
might go wrong with it.

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00:18:08,510 --> 00:18:15,510
And, in fact, as he said, they always breathe
a sigh of relief after first stage when the

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abort rocket would detach and fire itself
away.

222
00:18:20,290 --> 00:18:20,750
Yeah.

223
00:18:20,750 --> 00:18:27,750
If one of the engines is not working or not
working properly, I guess the other two engines

224
00:18:28,880 --> 00:18:32,240
try to do the work [NOISE OBSCURES].

225
00:18:32,240 --> 00:18:38,060
Well, they certainly will throttle up to 109%
if they need to, but they cannot make up for

226
00:18:38,060 --> 00:18:42,540
the first engine when you're in the first
stage and you have lots of gravity losses.

227
00:18:42,540 --> 00:18:49,540
In fact, when you get, like I said, to about
3.5, 4 minutes then you have enough altitude

228
00:18:52,390 --> 00:18:54,670
and downrange velocity to make it across.

229
00:18:54,670 --> 00:19:01,670
And then at some point you get to the situation
where you basically gained your altitude.

230
00:19:02,440 --> 00:19:07,630
And, although you are not at orbital velocity
yet so you still have some gravity losses,

231
00:19:07,630 --> 00:19:14,630
the gravity losses are small enough that if
you have a loss of an engine you can still

232
00:19:15,260 --> 00:19:17,280
make it to a lower orbit.

233
00:19:17,280 --> 00:19:21,250
That is called abort to orbit, ATO.

234
00:19:21,250 --> 00:19:28,250
And you will hear the call press to ATO means
that you can now make it to a lower orbit

235
00:19:30,630 --> 00:19:33,520
which is the safest thing to do with two engines.

236
00:19:33,520 --> 00:19:39,120
And then a little bit later on you will hear
like single engine TAL which means if you

237
00:19:39,120 --> 00:19:43,120
lose two engines with only one engine you
can make it across the Atlantic.

238
00:19:43,120 --> 00:19:48,140
And then later on you will hear single engine
ATO and then finally single engine.

239
00:19:48,140 --> 00:19:52,300
Then you will also hear press to MECO which
means at this point if you lose an engine

240
00:19:52,300 --> 00:19:54,230
you can make it through your nominal orbit.

241
00:19:54,230 --> 00:19:59,560
And usually about the last call a single engine
press to MECO which means even if you lose

242
00:19:59,560 --> 00:20:02,880
two engines you can still make it to MECO.

243
00:20:02,880 --> 00:20:09,880
What happens then if there

244
00:20:21,110 --> 00:20:23,520
is an instrumentation problem [NOISE OBSCURES]?

245
00:20:23,520 --> 00:20:30,520
The crew will never declare an abort on their
own because it is just realized that the ground

246
00:20:31,910 --> 00:20:33,140
has so much more information.

247
00:20:33,140 --> 00:20:36,330
The only exception is if you lose comm.

248
00:20:36,330 --> 00:20:41,210
If we had lost comm.

249
00:20:41,210 --> 00:20:48,210
and we saw our engine at 40%, I mean there
were a few other displays which the pilot

250
00:20:48,390 --> 00:20:50,180
was starting to call up.

251
00:20:50,180 --> 00:20:56,110
And it could be that he would have figured
it out perhaps, perhaps not, but that is the

252
00:20:56,110 --> 00:21:00,840
only circumstance under which the crew would
make that call.

253
00:21:00,840 --> 00:21:04,230
There was abort at some stage.

254
00:21:04,230 --> 00:21:06,120
What happened to that?

255
00:21:06,120 --> 00:21:08,180
Did they manage to make it [OVERLAPPING VOICES]?

256
00:21:08,180 --> 00:21:09,490
I was trying to remember.

257
00:21:09,490 --> 00:21:12,840
Did I talk about that in class?

258
00:21:12,840 --> 00:21:19,840
Well, all right, I will run through that because
it was, again, a very interesting story.

259
00:21:19,950 --> 00:21:25,790
The things that you are afraid about is that
if things go back in a hurry in an engine

260
00:21:25,790 --> 00:21:27,580
that an engine can actually blow up.

261
00:21:27,580 --> 00:21:30,930
And it is one thing if an engine gets shutdown.

262
00:21:30,930 --> 00:21:32,690
Now you are just flying on two engines.

263
00:21:32,690 --> 00:21:38,950
But if an engine blows up and takes out your
whole rear section you have had a bad day.

264
00:21:38,950 --> 00:21:45,950
The instrumentation is biased towards an early
shutdown.

265
00:21:46,220 --> 00:21:50,070
If you sense that something has gone wrong
shut it down.

266
00:21:50,070 --> 00:21:53,660
We have got intact aborts.

267
00:21:53,660 --> 00:21:59,700
Better to err on the side of safety, even
if that might potentially put you into an

268
00:21:59,700 --> 00:22:00,710
abort situation.

269
00:22:00,710 --> 00:22:07,710
And I am trying to exactly reconstruct it.

270
00:22:08,860 --> 00:22:15,860
The thing is that if you lose one engine now
you are abort ATO.

271
00:22:19,650 --> 00:22:26,650
Now, if you lose a second engine you might
be in a situation where certainly you cannot

272
00:22:28,470 --> 00:22:30,410
make it to orbit.

273
00:22:30,410 --> 00:22:34,950
And, because you have changed your trajectory,
you might not be able to make it to a good

274
00:22:34,950 --> 00:22:37,220
Trans-Atlantic landing site.

275
00:22:37,220 --> 00:22:44,220
So, at that point, if you have lost one engine
there is a switch on the center console where

276
00:22:48,600 --> 00:22:52,040
you can override the engine shutdown command.

277
00:22:52,040 --> 00:22:59,040
What you are now saying is we are in an unsurvivable
situation if we only have one engine.

278
00:23:00,230 --> 00:23:07,230
And, therefore, we will take the extra chance
of getting an instrumentation caused engine

279
00:23:07,720 --> 00:23:08,300
shutdown.

280
00:23:08,300 --> 00:23:14,110
We are not going to take that chance so we
are going to disable the ability of instrumentation

281
00:23:14,110 --> 00:23:18,530
to shut down the engine and we will just take
our chances.

282
00:23:18,530 --> 00:23:21,240
The ground will continue the calculation.

283
00:23:21,240 --> 00:23:25,570
And, as soon as you get to the point where
you have the capability of doing a single

284
00:23:25,570 --> 00:23:31,840
engine TAL or a single engine abort to orbit,
you re-enable the instrumentation.

285
00:23:31,840 --> 00:23:38,840
What happened is the Shuttle launched.

286
00:23:40,990 --> 00:23:47,860
It must have been about 4 or 5 minutes into
launch because they lost an engine, it shut

287
00:23:47,860 --> 00:23:54,860
down automatically, they are now abort to
orbit lower orbit, but they were abort to

288
00:23:55,150 --> 00:23:56,240
orbit.

289
00:23:56,240 --> 00:23:59,970
Take the switch, put it to inhibit.

290
00:23:59,970 --> 00:24:05,420
Now, the main propulsion flight controller
was very good.

291
00:24:05,420 --> 00:24:12,420
She realized right away that it was an instrumentation
problem because sometimes you can see certain

292
00:24:12,710 --> 00:24:17,090
trends or you see things change in a way that
tells you that this is not the way a real

293
00:24:17,090 --> 00:24:21,720
engine behaves, that this is more typical
of instrumentation.

294
00:24:21,720 --> 00:24:24,910
She suspected she had an instrumentation problem.

295
00:24:24,910 --> 00:24:30,910
Now they get a little further along in the
launch where they could have potentially done

296
00:24:30,910 --> 00:24:37,850
-- They were too far to land in the normal
TAL sites which were in the daytime on the

297
00:24:37,850 --> 00:24:44,550
West Coast of Africa, but they could have
made a nighttime landing at some emergency

298
00:24:44,550 --> 00:24:49,380
airport in the Congo, I think it was, if they
had lost another engine.

299
00:24:49,380 --> 00:24:56,380
But, by the flight rules, they take the switch
back to enable so that now, because you can

300
00:24:58,410 --> 00:25:05,410
"safely" lose a second engine you want to
protect yourself against an explosive situation.

301
00:25:05,580 --> 00:25:07,640
So, now they are enabled.

302
00:25:07,640 --> 00:25:13,400
Now the flight controller sees that the instrumentation
on one of the other two engines is starting

303
00:25:13,400 --> 00:25:16,910
to go back the way the first one was.

304
00:25:16,910 --> 00:25:23,440
And she realized that in about 15 seconds
that engine was going to shut down so she

305
00:25:23,440 --> 00:25:29,820
immediately called the flight director and
said flight, take the switch back to inhibit.

306
00:25:29,820 --> 00:25:35,790
And this is where the discipline becomes very
important, luckily flight didn't get into

307
00:25:35,790 --> 00:25:40,940
a long involved discussion about why do you
want to do that, what is going on, but just

308
00:25:40,940 --> 00:25:46,160
said CAPCOM engine switch to inhibit.

309
00:25:46,160 --> 00:25:47,270
They took it.

310
00:25:47,270 --> 00:25:51,570
And sure enough the instrumentation went bad
but the engine was OK.

311
00:25:51,570 --> 00:25:53,400
They got to orbit.

312
00:25:53,400 --> 00:25:56,640
Then they used some of their OMS propellant
to raise their orbit a little bit.

313
00:25:56,640 --> 00:25:58,490
That was a Spacelab mission.

314
00:25:58,490 --> 00:26:00,100
And they had a good mission.

315
00:26:00,100 --> 00:26:06,360
But the flight controller actually won a big
award for that because she really saved the

316
00:26:06,360 --> 00:26:08,380
day.

317
00:26:08,380 --> 00:26:13,430
So, yeah, that is the closest we ever came
to a real intact abort.

318
00:26:13,430 --> 00:26:14,070
Yeah.

319
00:26:14,070 --> 00:26:15,340
Two questions.

320
00:26:15,340 --> 00:26:20,340
The first one is going back to the return
to launch site.

321
00:26:20,340 --> 00:26:22,880
Do all of the main engine propellant get used
up before the tank gets dropped or do you

322
00:26:22,880 --> 00:26:26,820
not burn some of the propellant?

323
00:26:26,820 --> 00:26:28,270
You know, I don't know the answer to that.

324
00:26:28,270 --> 00:26:28,970
I don't.

325
00:26:28,970 --> 00:26:34,740
And the other one is on the pad, with your
flight, wouldn't the sequencing computer shut

326
00:26:34,740 --> 00:26:37,400
down the other engines if it detected that
one of them had failed?

327
00:26:37,400 --> 00:26:40,600
And so it must have used the good sensor.

328
00:26:40,600 --> 00:26:42,250
Yeah, that is right.

329
00:26:42,250 --> 00:26:47,210
And, luckily, our little gauge was just fed
by one.

330
00:26:47,210 --> 00:26:51,440
And, in retrospect, you can say probably that's
not a good way to design it but that is the

331
00:26:51,440 --> 00:26:52,100
way it was designed.

332
00:26:52,100 --> 00:26:52,850
You're right.

333
00:26:52,850 --> 00:26:59,450
If the engine controller senses with a majority
or however they program it, I don't know the

334
00:26:59,450 --> 00:27:01,390
details of the guts of the software there.

335
00:27:01,390 --> 00:27:05,530
But if it is convinced that one of the engines
is not working right it shuts down all three

336
00:27:05,530 --> 00:27:10,620
engines, which is what happened on four occasions.

337
00:27:10,620 --> 00:27:11,020
Yeah.

338
00:27:11,020 --> 00:27:18,020
When you talked about the forced pitch over
in the return to launch site, was that just

339
00:27:21,900 --> 00:27:22,280
the gambling of the main engines that gives
you that?

340
00:27:22,280 --> 00:27:23,770
Yeah, because you are off the solids at that
point.

341
00:27:23,770 --> 00:27:24,700
And that is the thing.

342
00:27:24,700 --> 00:27:31,310
I mean with the solids there is such an enormous
thrust and the aerodynamic loads are huge.

343
00:27:31,310 --> 00:27:35,500
You don't want to deviate from your planned
trajectory because one of the things that

344
00:27:35,500 --> 00:27:40,980
they do is program in load relief for the
aerodynamic surfaces.

345
00:27:40,980 --> 00:27:44,590
They take the day of winds launch.

346
00:27:44,590 --> 00:27:51,090
And, if you have wind shears or other atmospheric
high jet streams that you are going to fly

347
00:27:51,090 --> 00:27:58,090
through, they actually program the elevons
and the body flap to move in such a way as

348
00:27:58,790 --> 00:28:01,860
to relieve the aerodynamic loading on the
wings.

349
00:28:01,860 --> 00:28:03,880
And that is preprogrammed in.

350
00:28:03,880 --> 00:28:05,950
It is not a closed loop.

351
00:28:05,950 --> 00:28:11,100
It is totally open loop so you don't want
to change the trajectory once you've put all

352
00:28:11,100 --> 00:28:11,920
that load relief in.

353
00:28:11,920 --> 00:28:16,330
How long does that take?

354
00:28:16,330 --> 00:28:17,640
It's pretty quick.

355
00:28:17,640 --> 00:28:20,620
It's about ten seconds, if I remember from
the simulator.

356
00:28:20,620 --> 00:28:25,270
It is a sporty maneuver, I will tell you.

357
00:28:25,270 --> 00:28:26,510
No RCS that goes into that?

358
00:28:26,510 --> 00:28:31,560
Oh, the RCS is trivial compared to what you're
getting out.

359
00:28:31,560 --> 00:28:35,810
You've got 500,000 pounds coming out of each
engine.

360
00:28:35,810 --> 00:28:42,810
The primary RCS is 750 pounds.

361
00:28:46,240 --> 00:28:51,630
But, like I said, they do then open up the
RCS as you are flying back.

362
00:28:51,630 --> 00:28:56,510
And what they do is they open up all the engines
so that you have symmetrical thrusts so that

363
00:28:56,510 --> 00:29:01,010
you are firing out of both sides.

364
00:29:01,010 --> 00:29:07,740
The idea is just to deplete the tanks as much
as possible.

365
00:29:07,740 --> 00:29:14,740
The second technical area that I had been
hoping that Al Louviere would get into and

366
00:29:16,620 --> 00:29:21,470
didn't have a chance to was the payload bay
doors which are a fascinating mechanism.

367
00:29:21,470 --> 00:29:28,470
And it is also going to be a segue into EVA
because it was a strange situation.

368
00:29:30,160 --> 00:29:34,700
It is kind of relate back to that now when
you look at how many successful EVAs have

369
00:29:34,700 --> 00:29:39,650
been done and the Hubble repair and the building
of Space Station and all the other things,

370
00:29:39,650 --> 00:29:46,650
but management at Johnson Space Center was
not particularly friendly to EVA back in the

371
00:29:50,920 --> 00:29:51,830
`70s.

372
00:29:51,830 --> 00:29:55,480
I asked Chris Kraft about that.

373
00:29:55,480 --> 00:29:57,100
At first he denied it.

374
00:29:57,100 --> 00:29:59,320
He said well, I always liked EVA.

375
00:29:59,320 --> 00:30:04,510
He said well, maybe it was the management
of the Astronaut Office that didn't like EVA.

376
00:30:04,510 --> 00:30:08,750
He did admit that Bob Gilruth who was the
Director of Johnson Space Center at the time,

377
00:30:08,750 --> 00:30:14,620
this was when Chris Kraft was head of flight
operations, definitely did not like EVA.

378
00:30:14,620 --> 00:30:15,350
He was afraid of it.

379
00:30:15,350 --> 00:30:22,350
He didn't think it was safe, despite the fact
that back in 1973 EVA had saved the entire

380
00:30:23,760 --> 00:30:26,060
Skylab project.

381
00:30:26,060 --> 00:30:27,540
Hopefully most of you know that story.

382
00:30:27,540 --> 00:30:30,730
I know it is ancient history.

383
00:30:30,730 --> 00:30:37,530
And clearly we had done a lot of safe EVAs
on the surface of the Moon, but basically

384
00:30:37,530 --> 00:30:44,530
EVA was looked at it was expensive, it was
potentially hazardous.

385
00:30:44,860 --> 00:30:51,120
Given the things that the Shuttle was supposed
to do in the original planning, mainly launch

386
00:30:51,120 --> 00:30:57,140
satellites, launch pieces of the Space Station,
that went away, Launch Defense Department

387
00:30:57,140 --> 00:31:04,140
satellites, commercial satellites, EVA was
not really part of the big picture in planning.

388
00:31:04,160 --> 00:31:11,160
And, although they did design an airlock for
the Shuttle, there were real questions of

389
00:31:15,120 --> 00:31:17,170
how much preparation do we have to do for
EVA?

390
00:31:17,170 --> 00:31:18,380
Do we really even need it?

391
00:31:18,380 --> 00:31:25,380
Maybe we could save some weight by not having
space suits aboard.

392
00:31:39,990 --> 00:31:46,990
That is

393
00:32:02,030 --> 00:32:03,100
where we finally ended up.

394
00:32:03,100 --> 00:32:05,310
That is the Hubble Telescope.

395
00:32:05,310 --> 00:32:08,600
This is the side of the payload bay.

396
00:32:08,600 --> 00:32:11,930
I mean, obviously, EVA became a very successful
activity.

397
00:32:11,930 --> 00:32:15,340
These are the payload bay doors.

398
00:32:15,340 --> 00:32:20,430
This is in the orbiter processing facility.

399
00:32:20,430 --> 00:32:27,430
And one of the things, well, I have a picture
of closing the door.

400
00:32:28,730 --> 00:32:33,220
But the mechanism of these doors is extraordinary.

401
00:32:33,220 --> 00:32:38,480
There are two motors, one at the front and
one at the back of each.

402
00:32:38,480 --> 00:32:44,810
Each of the motors has two drive units and
they work through a differential so that if

403
00:32:44,810 --> 00:32:51,810
one of the motors fails the other one can
still drive although at half the speed, just

404
00:32:52,270 --> 00:32:55,610
similar to the way a car works.

405
00:32:55,610 --> 00:33:00,740
There is a long torsion rod which runs the
length of the Shuttle.

406
00:33:00,740 --> 00:33:05,130
And then that torsion rod is attached to these
bars over here.

407
00:33:05,130 --> 00:33:11,510
And I am sorry the picture was scanned in
and is not terribly sharp.

408
00:33:11,510 --> 00:33:18,510
As the torsion bar twists then these rods
lift up the payload bay door and bring it

409
00:33:20,070 --> 00:33:21,250
to a close.

410
00:33:21,250 --> 00:33:26,090
The mechanism, this is the best picture I
could find, you notice there is a strong back

411
00:33:26,090 --> 00:33:32,390
because, as was mentioned, the doors cannot
support their own weight in 1G.

412
00:33:32,390 --> 00:33:39,390
But the system of latches here, you have to
remember that the payload bay can expand and

413
00:33:39,520 --> 00:33:45,440
contract by several inches due to thermal
environment.

414
00:33:45,440 --> 00:33:52,440
And so you have to design a latch system that
can accommodate this thermal behavior.

415
00:33:53,930 --> 00:33:56,950
It was an incredible mechanical challenge.

416
00:33:56,950 --> 00:34:02,400
And the complexity of this system, I mean
I am always amazed when I look at how the

417
00:34:02,400 --> 00:34:02,930
thing works.

418
00:34:02,930 --> 00:34:09,399
I have a schematic of them later, which you
can look at, but basically you close the doors.

419
00:34:09,399 --> 00:34:14,280
And then the first thing you do is you want
to close the latches on either end.

420
00:34:14,280 --> 00:34:16,349
And then there is also center line latches.

421
00:34:16,349 --> 00:34:22,239
And I think Al Louviere did discuss the fact
that these payload bay doors are part of the

422
00:34:22,239 --> 00:34:26,399
structural element of the Shuttle during reentry.

423
00:34:26,399 --> 00:34:32,000
You cannot reenter if the doors are not just
closed by latched.

424
00:34:32,000 --> 00:34:35,820
You need them latched for structural strength.

425
00:34:35,820 --> 00:34:42,820
There is a series of bollards here, little
protrusions which these latches grab on.

426
00:34:44,330 --> 00:34:51,330
And they have designed the rigging of the
rods such that the latches that are close

427
00:34:56,149 --> 00:35:02,420
to the hinge line actually close before the
latches that are further away.

428
00:35:02,420 --> 00:35:09,100
It is a sequential closing of the latches
all with a single mechanism so that basically

429
00:35:09,100 --> 00:35:16,100
you pull the part of the door that is closest
to the torque rod, you latch that down first,

430
00:35:17,230 --> 00:35:21,510
and then it is kind of a zipper effect where
then you pull it down so that even if the

431
00:35:21,510 --> 00:35:26,660
door is a little bit warped thermally you
will get the door to close properly.

432
00:35:26,660 --> 00:35:33,660
You wouldn't want to close this latch first
and then have the door in a situation where

433
00:35:33,720 --> 00:35:37,010
it was buckled out.

434
00:35:37,010 --> 00:35:41,180
And then, of course, the center line latch,
because of the thermal expansion, you can

435
00:35:41,180 --> 00:35:44,480
have the doors coming together like that or
like that.

436
00:35:44,480 --> 00:35:47,580
And you have got to have centerline latches
that can accommodate for that.

437
00:35:47,580 --> 00:35:51,260
It is really quite an incredible design.

438
00:35:51,260 --> 00:35:55,520
And Al Louviere had said that he was going
to talk about it, but he didn't have time

439
00:35:55,520 --> 00:35:59,270
to.

440
00:35:59,270 --> 00:36:04,380
There is plenty of redundancy in here because
there are these double motors, but because

441
00:36:04,380 --> 00:36:11,380
this is so critical people started to look
at suppose you have some degree stuck in the

442
00:36:11,850 --> 00:36:18,230
mechanism, it doesn't matter how many motors,
you cannot get it closed.

443
00:36:18,230 --> 00:36:22,570
Suppose the motors jam on one side.

444
00:36:22,570 --> 00:36:25,600
Now the other motor is not going to be able
to drive it.

445
00:36:25,600 --> 00:36:30,500
So, various things were done to allow for
EVA intervention.

446
00:36:30,500 --> 00:36:34,600
And, in the early Shuttle flights, this was
the only thing that the crew trained for with

447
00:36:34,600 --> 00:36:39,370
EVA, it was just payload bay door contingencies.

448
00:36:39,370 --> 00:36:46,370
For instance, the PDU, the drive unit, this
is the payload bay door drive unit or PLBDU.

449
00:36:50,750 --> 00:36:54,230
That is what we call a nested acronym.

450
00:36:54,230 --> 00:36:56,730
That is part of the game there.

451
00:36:56,730 --> 00:37:00,760
You have to go out and actually peel away
the liners of the payload bay.

452
00:37:00,760 --> 00:37:07,760
And inside here there is a little mechanism
where you can insert a special tool and twist

453
00:37:09,000 --> 00:37:09,680
it.

454
00:37:09,680 --> 00:37:16,680
And that actually disconnects that motor drive
unit from the torque so that it can turn freely.

455
00:37:19,560 --> 00:37:24,790
And I hope, when you look at these things,
you will get some sense of the complexity

456
00:37:24,790 --> 00:37:26,680
of these mechanisms.

457
00:37:26,680 --> 00:37:33,680
And so what we do for training -- Of course
they build mockups of this in the water and

458
00:37:34,000 --> 00:37:38,490
we also look at the real Shuttle down in Florida
to actually see these units.

459
00:37:38,490 --> 00:37:42,890
And, for the people who are on the EVA crew,
you spend a lot of time crawling around the

460
00:37:42,890 --> 00:37:47,810
payload bay getting intimately familiar with
a lot of the actual mechanisms just in case

461
00:37:47,810 --> 00:37:54,810
you actually have to go out and do something
with it.

462
00:37:54,880 --> 00:38:01,880
Then suppose the problem is not with the drive
unit but that one of these latches get jammed

463
00:38:03,290 --> 00:38:03,860
up.

464
00:38:03,860 --> 00:38:06,350
This is actually a tube cutter.

465
00:38:06,350 --> 00:38:08,100
It is a little hard to see.

466
00:38:08,100 --> 00:38:11,690
I don't know if you are familiar with the
things.

467
00:38:11,690 --> 00:38:12,480
They are on a ratchet.

468
00:38:12,480 --> 00:38:18,790
And, as it gradually cuts, you push the blade
in bit by bit.

469
00:38:18,790 --> 00:38:20,500
And then eventually you cut away.

470
00:38:20,500 --> 00:38:27,280
And this gives you an idea that they just
gave us a lot of tools, a pin extractor, a

471
00:38:27,280 --> 00:38:31,220
crowbar, vice grips, you name it.

472
00:38:31,220 --> 00:38:34,000
How much did that crowbar cost?

473
00:38:34,000 --> 00:38:38,660
Well, the crowbar probably cost about $10
at Sears.

474
00:38:38,660 --> 00:38:45,660
And then they had to put on all of the Velcro
and the tethers to go in the tool thing, and

475
00:38:45,690 --> 00:38:47,860
that probably cost a few hundred dollars.

476
00:38:47,860 --> 00:38:50,890
And then they had to make a drawing of it,
and you know how it goes.

477
00:38:50,890 --> 00:38:56,250
EVA is very expensive because everything has
to be custom made.

478
00:38:56,250 --> 00:39:03,180
I mean that is one of the things that, because
of the constraints of the suits and the gloves,

479
00:39:03,180 --> 00:39:07,750
you cannot, in most case, just use regular
tools.

480
00:39:07,750 --> 00:39:10,300
And, as I say, everything is tethered.

481
00:39:10,300 --> 00:39:11,650
And I will show you pictures later.

482
00:39:11,650 --> 00:39:13,070
We have a little mini workstation.

483
00:39:13,070 --> 00:39:18,500
They built little receptacles on the side
of the suit because it is a hard upper torso

484
00:39:18,500 --> 00:39:20,270
which can take a certain amount of load.

485
00:39:20,270 --> 00:39:25,310
And so you plug basically a tool caddy into
your suit.

486
00:39:25,310 --> 00:39:28,800
And then you hang all of these tools on the
tool caddy.

487
00:39:28,800 --> 00:39:35,070
And you will see some pictures later of how
that works.

488
00:39:35,070 --> 00:39:42,070
If the motors don't work and you have now
freed the doors so that the door can move

489
00:39:42,630 --> 00:39:49,630
but you have no motor to drive it, now we
have a mechanical winch and a rope on it.

490
00:39:49,920 --> 00:39:55,750
And I'm not making this up.

491
00:39:55,750 --> 00:39:56,990
You actually run the rope up.

492
00:39:56,990 --> 00:40:00,820
These are the little bollards that the latches
catch onto.

493
00:40:00,820 --> 00:40:06,030
You run the rope up over that and then you
have to crawl out on the payload bay door,

494
00:40:06,030 --> 00:40:09,760
which would be a lot of fun, and attach it
here.

495
00:40:09,760 --> 00:40:13,570
And then you actually wind it closed.

496
00:40:13,570 --> 00:40:14,750
And we do this in the water.

497
00:40:14,750 --> 00:40:16,840
I mean this is all fully mocked up.

498
00:40:16,840 --> 00:40:17,820
Yeah.

499
00:40:17,820 --> 00:40:23,090
What do you do if you have trouble opening
the doors just after launch?

500
00:40:23,090 --> 00:40:28,630
Well, if you cannot open the doors then you
come home.

501
00:40:28,630 --> 00:40:29,470
You wouldn't want to.

502
00:40:29,470 --> 00:40:33,400
I mean if there was something seriously wrong
with the doors you better come home.

503
00:40:33,400 --> 00:40:38,180
Yeah, we can do this to get them closed.

504
00:40:38,180 --> 00:40:42,050
But you don't want to purposely put yourself
in that situation if you know you have a problem

505
00:40:42,050 --> 00:40:43,530
beforehand.

506
00:40:43,530 --> 00:40:45,010
Yeah.

507
00:40:45,010 --> 00:40:47,980
[NOISE OBSCURES]

508
00:40:47,980 --> 00:40:50,180
We think it could be done with one person.

509
00:40:50,180 --> 00:40:51,730
Normally, we only go out with two.

510
00:40:51,730 --> 00:40:56,920
But in the orbital flight test, the first
four flights only had two crew members.

511
00:40:56,920 --> 00:41:02,440
Was of them was EVA trained.

512
00:41:02,440 --> 00:41:07,750
And then what happens if you get the doors
closed by the latches don't latch?

513
00:41:07,750 --> 00:41:13,570
They actually made latches that we could put
on by hand.

514
00:41:13,570 --> 00:41:14,990
These are the latches for the side.

515
00:41:14,990 --> 00:41:21,560
And this is the schematic that sort of show
the latches going on the orders in that order

516
00:41:21,560 --> 00:41:23,820
one, two, three and four.

517
00:41:23,820 --> 00:41:28,920
And, again, the way they designed this so
that they actually close in sequence but you

518
00:41:28,920 --> 00:41:34,890
only have one drive unit is really just a
beautiful mechanical system.

519
00:41:34,890 --> 00:41:41,320
But if they don't close then you take this,
and I won't go into the details, but you have

520
00:41:41,320 --> 00:41:44,460
to spring it around at least two of those.

521
00:41:44,460 --> 00:41:48,460
And that will give you the structural strength
to come home.

522
00:41:48,460 --> 00:41:54,510
And then if the center line latches don't
close, again, you can look at the mechanism

523
00:41:54,510 --> 00:41:54,760
here.

524
00:41:54,670 --> 00:41:56,490
And they have yet a different tool.

525
00:41:56,490 --> 00:42:01,580
Now, this is actually shown on its side, but
this is actually on the top.

526
00:42:01,580 --> 00:42:06,860
And this is a bitch in the water because,
yeah, your suit is weightless but the tool

527
00:42:06,860 --> 00:42:07,740
is not.

528
00:42:07,740 --> 00:42:10,920
And so you are holding this tool.

529
00:42:10,920 --> 00:42:15,060
When you're holding the tool you want to sink
to the bottom, and so you are trying to hold

530
00:42:15,060 --> 00:42:15,770
on with one hand.

531
00:42:15,770 --> 00:42:22,740
And you have a tether so you try to tie yourself
to the top there so that you're kind of hanging

532
00:42:22,740 --> 00:42:23,300
on the tether.

533
00:42:23,300 --> 00:42:30,050
But then, depending on how your weigh out
is, if you move this big tool back and forth

534
00:42:30,050 --> 00:42:32,680
your body is sort of rocking back and forth.

535
00:42:32,680 --> 00:42:36,390
And you are working above your head.

536
00:42:36,390 --> 00:42:39,510
I mean everybody has to do it.

537
00:42:39,510 --> 00:42:45,430
If you are going to be an EVA crew member
and you cannot do this job you are disqualified.

538
00:42:45,430 --> 00:42:47,670
But nobody likes it.

539
00:42:47,670 --> 00:42:51,650
It is a real pain.

540
00:42:51,650 --> 00:42:56,010
That is basically how EVA got sold to the
Shuttle System.

541
00:42:56,010 --> 00:43:02,140
I will show you a few pictures of general
EVA activities to give you an idea of how

542
00:43:02,140 --> 00:43:03,150
the system works.

543
00:43:03,150 --> 00:43:10,150
And then I want to go into the question of
the interaction between EVA and the pressurization

544
00:43:14,210 --> 00:43:18,560
and the environmental control system of the
rest of the Shuttle because, again, this is

545
00:43:18,560 --> 00:43:20,050
a systems engineering problem.

546
00:43:20,050 --> 00:43:26,440
And you cannot, in most cases, do one thing
without it having an impact on something else.

547
00:43:26,440 --> 00:43:31,369
I talked about doing all this training.

548
00:43:31,369 --> 00:43:37,780
Now we are stepping ten years into the future
so that is training for the Hubble Telescope.

549
00:43:37,780 --> 00:43:43,540
And, actually, the telescope is so tall that
we couldn't get the whole thing in.

550
00:43:43,540 --> 00:43:48,970
The pool wasn't deep enough so we had to actually
cut it in half, and we would work on one half

551
00:43:48,970 --> 00:43:54,530
and then work on the other half.

552
00:43:54,530 --> 00:43:55,180
Here is an example.

553
00:43:55,180 --> 00:43:59,650
This is me installing the Wide Field/Planetary
Camera.

554
00:43:59,650 --> 00:44:06,650
Now, the training, people normally see the
water tank.

555
00:44:10,180 --> 00:44:11,130
You're not weightless.

556
00:44:11,130 --> 00:44:13,150
You all understand that.

557
00:44:13,150 --> 00:44:15,990
If you go upside down the blood rushes to
your head.

558
00:44:15,990 --> 00:44:20,710
If you're holding onto tools, the tools will
fall down.

559
00:44:20,710 --> 00:44:25,460
And of course you don't have these guys when
you're out in space.

560
00:44:25,460 --> 00:44:32,460
Angels if you saw them out in space.

561
00:44:32,890 --> 00:44:39,890
If you're moving around large objects, they
have resistance from the water, so you need

562
00:44:40,760 --> 00:44:45,940
to get a sense of how easy it is to push things
around so you don't get things moving too

563
00:44:45,940 --> 00:44:46,630
fast.

564
00:44:46,630 --> 00:44:50,770
We also train on air bearing floors.

565
00:44:50,770 --> 00:44:55,930
This is a mass model of the Wiff-Pick.

566
00:44:55,930 --> 00:45:00,400
The same mass, moments of inertia.

567
00:45:00,400 --> 00:45:04,430
And I am up here on a weight relief system.

568
00:45:04,430 --> 00:45:08,220
And you can really get a sense of what it
feels like.

569
00:45:08,220 --> 00:45:13,310
And so you are trying to build a kind of muscle
memory so that when you get in space you are

570
00:45:13,310 --> 00:45:19,480
not trying to push things as hard as you push
them in the water.

571
00:45:19,480 --> 00:45:23,980
And you also remember that if you want to
stop something you also have to be able to

572
00:45:23,980 --> 00:45:25,040
exert a force on it.

573
00:45:25,040 --> 00:45:31,000
Whereas, in the water, all you have to do
is stop pushing.

574
00:45:31,000 --> 00:45:33,970
Now we go into space and we are ready for
the EVA.

575
00:45:33,970 --> 00:45:40,750
I will sort of take you through what is involved
to give you a sense of the complexity of this

576
00:45:40,750 --> 00:45:43,470
system.

577
00:45:43,470 --> 00:45:46,450
First of all are tools.

578
00:45:46,450 --> 00:45:49,970
That is what I looked like before all the
cosmic rays made my hair fall out.

579
00:45:49,970 --> 00:45:54,520
It is just one of the hazards of spaceflight.

580
00:45:54,520 --> 00:45:56,770
Here you see the kind of tool caddies.

581
00:45:56,770 --> 00:46:00,940
This is for a ratchet wrench.

582
00:46:00,940 --> 00:46:04,230
And we had about 250 different tools.

583
00:46:04,230 --> 00:46:08,280
About a hundred planned to use and the rest
were for contingencies.

584
00:46:08,280 --> 00:46:10,440
And we had to take them all out.

585
00:46:10,440 --> 00:46:12,980
We call this our fish stringer.

586
00:46:12,980 --> 00:46:15,540
Sort of like a Portuguese fishermen.

587
00:46:15,540 --> 00:46:19,780
The fisher wives hang all the fish on the
string and then hang them out.

588
00:46:19,780 --> 00:46:25,740
And then we take this out on the fish stringer.

589
00:46:25,740 --> 00:46:29,110
This is the airlock at launch.

590
00:46:29,110 --> 00:46:31,290
And it is totally packed.

591
00:46:31,290 --> 00:46:35,560
And, in fact, we had four spacesuits rather
than the normal two so there wasn't a whole

592
00:46:35,560 --> 00:46:36,240
lot of room.

593
00:46:36,240 --> 00:46:41,619
And the first thing is you go and you start
checking the various systems.

594
00:46:41,619 --> 00:46:48,619
And then you have to unpack everything and
move it into the flight deck.

595
00:46:48,880 --> 00:46:49,650
That is Story.

596
00:46:49,650 --> 00:46:53,230
We went out together.

597
00:46:53,230 --> 00:46:55,450
This is the hard upper torso.

598
00:46:55,450 --> 00:47:01,750
This is looking down into the inside of the
spacesuit.

599
00:47:01,750 --> 00:47:08,410
The back of the spacesuit there is battery
and lithium hydroxide CO2 scrubber.

600
00:47:08,410 --> 00:47:12,850
The CO2 scrubber has to be replaced after
every EVA.

601
00:47:12,850 --> 00:47:16,980
It is good for about 12 hours.

602
00:47:16,980 --> 00:47:22,350
And normally if you're only going out once
you don't worry about recharging the batteries,

603
00:47:22,350 --> 00:47:28,660
but since we were doing successive every day
EVAs we would have to take the batteries out

604
00:47:28,660 --> 00:47:29,800
every night and charge them.

605
00:47:29,800 --> 00:47:32,990
Take the ones that had been charged and put
them into the suits that are going to go out

606
00:47:32,990 --> 00:47:34,200
the next day.

607
00:47:34,200 --> 00:47:39,470
And just keeping track of which cartridges
have been used and which batteries have been

608
00:47:39,470 --> 00:47:46,470
charged and how much, I mean there is a tremendous
amount of overhead effort just in managing

609
00:47:46,780 --> 00:47:48,890
all of this equipment.

610
00:47:48,890 --> 00:47:55,890
And we had practiced doing this a lot on the
ground, as you can imagine, before we went

611
00:47:56,540 --> 00:47:57,350
up.

612
00:47:57,350 --> 00:48:00,150
The morning of the EVA.

613
00:48:00,150 --> 00:48:06,140
You get up early and eat as big a breakfast
as you can because you are not going to get

614
00:48:06,140 --> 00:48:09,330
much to eat for the next eight hours.

615
00:48:09,330 --> 00:48:12,710
These are radiation monitors.

616
00:48:12,710 --> 00:48:17,100
For Hubble we were actually up at about 600
kilometers, which is as high as the Shuttle

617
00:48:17,100 --> 00:48:24,100
ever goes, so we got really the highest radiation
dose that you can get on the Shuttle on a

618
00:48:25,320 --> 00:48:25,920
normal mission.

619
00:48:25,920 --> 00:48:30,930
It was about between one and two REMs which
is no big health problem.

620
00:48:30,930 --> 00:48:37,930
But typically the dose on a Shuttle flight
at a more typical 300 kilometers is more like

621
00:48:38,480 --> 00:48:43,590
tens or maybe a little over 100 milliREMs.

622
00:48:43,590 --> 00:48:45,930
They did want us to take the radiation monitor.

623
00:48:45,930 --> 00:48:47,460
Now we are in the mid-deck.

624
00:48:47,460 --> 00:48:52,690
And when you see these pictures you get a
sense of when you're doing an EVA the entire

625
00:48:52,690 --> 00:48:55,190
middeck is just full of stuff.

626
00:48:55,190 --> 00:48:58,580
I mean there is so much equipment.

627
00:48:58,580 --> 00:49:05,580
You've got the pants units floating over there,
plus the two extra suits and all of the auxiliary

628
00:49:05,640 --> 00:49:06,530
equipment.

629
00:49:06,530 --> 00:49:09,730
You try to keep things organized.

630
00:49:09,730 --> 00:49:16,730
Then for thermal control, the original Apollo
spacesuits were designed for daytime use on

631
00:49:20,020 --> 00:49:21,980
the Moon when it is very hot.

632
00:49:21,980 --> 00:49:26,880
And, in addition, people are walking so they
are putting a lot of metabolic heat into the

633
00:49:26,880 --> 00:49:27,550
suit.

634
00:49:27,550 --> 00:49:33,080
And so they were very concerned about being
able to have sufficient cooling.

635
00:49:33,080 --> 00:49:38,080
They developed a very, very efficient sublimator
cooling unit.

636
00:49:38,080 --> 00:49:45,080
You have a little layer of ice that is continually
fed from the bottom and it is sublimates.

637
00:49:45,160 --> 00:49:46,820
That basically is how you get rid of your
heat.

638
00:49:46,820 --> 00:49:51,900
And then you run your cooling water underneath
that ice and it cools off.

639
00:49:51,900 --> 00:49:58,050
And then it is run through what they call
LCVG, liquid cooling and ventilation garment

640
00:49:58,050 --> 00:50:05,050
which has lots of Tygon tubing that goes through
it so that it carries the cold water next

641
00:50:05,950 --> 00:50:06,550
to your skin.

642
00:50:06,550 --> 00:50:13,550
And also the oxygen that comes into the suit
comes through the helmet over the back of

643
00:50:14,500 --> 00:50:18,920
your head so it flows over your face so you
breathe the fresh oxygen.

644
00:50:18,920 --> 00:50:25,920
But you would like to get ventilation through
the entire suit so you don't build up lots

645
00:50:26,640 --> 00:50:28,950
of humidity in your arms and legs.

646
00:50:28,950 --> 00:50:34,600
What you do is the return valve actually comes
through these air ducts.

647
00:50:34,600 --> 00:50:40,420
And so the return is picked up at the bottom
of your arms and at the bottom of your legs.

648
00:50:40,420 --> 00:50:45,580
That insures that the air does get circulated
through your arms and legs.

649
00:50:45,580 --> 00:50:52,580
But when we started doing Shuttle EVAs metabolically
you are not nearly as stressed.

650
00:50:54,390 --> 00:51:01,340
Plus, you spend almost half your time in the
dark and it gets really, really cold.

651
00:51:01,340 --> 00:51:08,340
And this has been a constant problem.

652
00:51:09,350 --> 00:51:14,630
And here is an interesting systems problem
to show how everything relates to one another.

653
00:51:14,630 --> 00:51:20,420
We were very concerned about when you open
up the doors of the Hubble Telescope, if direct

654
00:51:20,420 --> 00:51:27,420
sunlight comes in, it will cause an out-gassing
of the internal material which could pollute

655
00:51:28,720 --> 00:51:30,170
the ultraviolet mirrors.

656
00:51:30,170 --> 00:51:37,170
The ultraviolet optics are very, very sensitive
to organic contamination, so under no circumstances

657
00:51:37,970 --> 00:51:42,500
could we have sunlight penetrating the interior
of the telescope.

658
00:51:42,500 --> 00:51:47,300
But we were going to be spending a lot of
time with the doors open, so how do you insure

659
00:51:47,300 --> 00:51:50,340
that you will never get the sun coming in?

660
00:51:50,340 --> 00:51:56,619
Well, the Hubble Telescope is sitting up here
like this.

661
00:51:56,619 --> 00:52:01,900
If that is the sun, just make sure that the
belly of the orbiter is always pointed towards

662
00:52:01,900 --> 00:52:02,290
the sun.

663
00:52:02,290 --> 00:52:06,800
Then you never have to worry about sun coming
into the telescope.

664
00:52:06,800 --> 00:52:13,170
But what you do have to worry about is that,
well, during the dayside of your orbit, if

665
00:52:13,170 --> 00:52:18,030
the sun is over here and the earth is over
here, during the day your payload bay is going

666
00:52:18,030 --> 00:52:19,580
to be pointed towards the earth.

667
00:52:19,580 --> 00:52:25,960
And so, you basically have a radiative heat
exchange with something that is at about 20

668
00:52:25,960 --> 00:52:26,750
degrees C.

669
00:52:26,750 --> 00:52:27,350
No big deal.

670
00:52:27,350 --> 00:52:33,220
If you go around the other side now, you at
nighttime, you're pointed at deep space.

671
00:52:33,220 --> 00:52:37,450
And so you're radiating towards absolute zero
or three degrees Kelvin.

672
00:52:37,450 --> 00:52:40,290
And that is a concern.

673
00:52:40,290 --> 00:52:41,260
And you get very cold.

674
00:52:41,260 --> 00:52:48,260
They were predicting temperatures of as much
as 150 below zero Celsius.

675
00:52:49,580 --> 00:52:55,480
We were very concerned not only were our hands
going to get cold but some of our tools might

676
00:52:55,480 --> 00:52:57,980
not work.

677
00:52:57,980 --> 00:53:04,980
We pushed very hard for a test in a thermal
vacuum chamber.

678
00:53:05,050 --> 00:53:10,020
Our tools are stored in a toolbox outside
in the cargo bay.

679
00:53:10,020 --> 00:53:15,210
And we wanted to go through going out and
taking the tools out.

680
00:53:15,210 --> 00:53:22,210
And, of course, they are held in there because
they have launch locks so there are little

681
00:53:22,290 --> 00:53:27,940
pit pins and latching mechanisms that you
have to remove so that you can get the tools

682
00:53:27,940 --> 00:53:28,850
out.

683
00:53:28,850 --> 00:53:30,619
I went in to do the first test.

684
00:53:30,619 --> 00:53:32,320
And it is a vacuum chamber.

685
00:53:32,320 --> 00:53:33,520
And the walls are painted black.

686
00:53:33,520 --> 00:53:38,450
And they can run liquid nitrogen through the
vacuum chamber.

687
00:53:38,450 --> 00:53:42,790
And they could cool it down to the lowest
temperatures that we were expecting to experience.

688
00:53:42,790 --> 00:53:49,790
I opened up the toolbox and about 75% of the
tools the launch release mechanisms were just

689
00:53:50,840 --> 00:53:51,570
frozen shut.

690
00:53:51,570 --> 00:53:52,980
I couldn't get them out.

691
00:53:52,980 --> 00:53:55,510
So, that started to get people's attention.

692
00:53:55,510 --> 00:53:59,820
They sent the engineers in to redo some of
the tolerance.

693
00:53:59,820 --> 00:54:04,220
They played around with the lubrication a
little bit.

694
00:54:04,220 --> 00:54:11,220
Then Story went in a week later to do his
run and he was able to get most of the tools

695
00:54:12,490 --> 00:54:12,990
out.

696
00:54:12,990 --> 00:54:19,030
I think he got all the tools out, actually,
because I was only in for a few hours.

697
00:54:19,030 --> 00:54:21,830
Because once we realized that it wasn't working
I came out.

698
00:54:21,830 --> 00:54:24,790
He was in there.

699
00:54:24,790 --> 00:54:29,660
I remember he said at one point just holding
onto these tools my hands are really, really

700
00:54:29,660 --> 00:54:30,160
cold.

701
00:54:30,160 --> 00:54:31,470
I don't know.

702
00:54:31,470 --> 00:54:33,920
About an hour or so later someone asked him
how his hands were.

703
00:54:33,920 --> 00:54:36,369
He said oh, they are fine, they've warmed
up.

704
00:54:36,369 --> 00:54:39,750
Well, Story is from the South.

705
00:54:39,750 --> 00:54:44,920
Those of you with experience in winter know
that if your hands are really cold and after

706
00:54:44,920 --> 00:54:48,920
a while you don't feel them anymore, it doesn't
necessarily mean that they have warmed up.

707
00:54:48,920 --> 00:54:53,510
When they took him out of the chamber his
hands were deep purplish black and he had

708
00:54:53,510 --> 00:55:00,510
severe frostbite to the point where they sent
him up to Alaska to some frostbite specialists.

709
00:55:01,790 --> 00:55:03,160
In the end, he was very fortunate.

710
00:55:03,160 --> 00:55:07,190
He got off with no major permanent damage
and was able to fly.

711
00:55:07,190 --> 00:55:10,700
But, as you can imagine, that got serious
management attention.

712
00:55:10,700 --> 00:55:14,270
So, gloves now have electrical heating units
in them.

713
00:55:14,270 --> 00:55:17,080
But we didn't have that available.

714
00:55:17,080 --> 00:55:24,080
What we had to do was to change the attitude
profile so that we were basically pointing

715
00:55:25,090 --> 00:55:26,750
towards the earth.

716
00:55:26,750 --> 00:55:29,730
Now, that is generally OK.

717
00:55:29,730 --> 00:55:35,470
If you are pointing towards the earth and
the sun is coming from your belly you are

718
00:55:35,470 --> 00:55:42,470
not going to hurt the Shuttle, but a quarter
way around the earth you do have the possibility

719
00:55:44,430 --> 00:55:49,540
now that the sun is going to hit the telescope.

720
00:55:49,540 --> 00:55:56,540
What they had to do was to do two attitude
maneuvers every orbit in order to basically

721
00:56:02,260 --> 00:56:05,580
keep us in a more benign thermal attitude
for the EVA.

722
00:56:05,580 --> 00:56:12,349
But to prevent the sun from shinning on the
telescope.

723
00:56:12,349 --> 00:56:17,040
And we didn't the reaction control system
propellant budget to support that.

724
00:56:17,040 --> 00:56:20,910
Remember we were going into a high orbit which
meant we needed to use a lot of OMS fuel to

725
00:56:20,910 --> 00:56:21,990
get up there?

726
00:56:21,990 --> 00:56:26,599
And we needed a lot of propellant for the
deorbit because the higher you are the more

727
00:56:26,599 --> 00:56:29,520
you have to burn to get down.

728
00:56:29,520 --> 00:56:36,520
And so the flight control community, together
with the pilots got together and developed

729
00:56:40,240 --> 00:56:45,460
a special way that we could do maneuvers using
only half the number of jets that you normally

730
00:56:45,460 --> 00:56:46,940
use.

731
00:56:46,940 --> 00:56:53,940
And so this is an interconnection between
the thermal environment of EVA and the reaction

732
00:56:55,280 --> 00:57:00,109
control propellant budget which nobody in
the early days of flight planning would ever

733
00:57:00,109 --> 00:57:02,650
have believed that there is this sort of connection.

734
00:57:02,650 --> 00:57:07,710
But it is just another good example of how
these systems all play with one another and

735
00:57:07,710 --> 00:57:11,880
you cannot make changes in one without another.

736
00:57:11,880 --> 00:57:16,130
I am going to finish this unit and then we
will take a little break and then I will do

737
00:57:16,130 --> 00:57:16,960
the last part.

738
00:57:16,960 --> 00:57:20,470
The process of getting in the suit.

739
00:57:20,470 --> 00:57:24,640
First you get in LTA, lower torso assembly,
basically the pants.

740
00:57:24,640 --> 00:57:29,320
And, of course, this is one time when you
can put your pants on both legs at a time.

741
00:57:29,320 --> 00:57:30,910
You cannot do that too often.

742
00:57:30,910 --> 00:57:35,670
But, again, look at the middeck here.

743
00:57:35,670 --> 00:57:36,740
It is full.

744
00:57:36,740 --> 00:57:39,760
This, by the way, is the escape pole.

745
00:57:39,760 --> 00:57:41,970
We talked about this earlier.

746
00:57:41,970 --> 00:57:48,970
During launch and entry it is actually bolted
into position so that it will take you out

747
00:57:49,790 --> 00:57:55,760
the door, but once you are in orbit you just
sort of float it up and out of the way and

748
00:57:55,760 --> 00:57:57,800
it just kind of Velcroed to the ceiling.

749
00:57:57,800 --> 00:58:01,980
And, of course, it has no weight up there
so it is perfectly happy.

750
00:58:01,980 --> 00:58:04,230
You get in the pants.

751
00:58:04,230 --> 00:58:11,109
Now, the upper torso of the suit is attached
to the wall inside the airlock.

752
00:58:11,109 --> 00:58:14,300
Now you have to float into the airlock.

753
00:58:14,300 --> 00:58:16,390
And that is what you're looking at when you're
getting into the suit.

754
00:58:16,390 --> 00:58:17,950
There are a lot of connections you have to
make.

755
00:58:17,950 --> 00:58:20,619
This is the water bag.

756
00:58:20,619 --> 00:58:22,830
This is the comm.

757
00:58:22,830 --> 00:58:26,030
connection for your Snoopy cap.

758
00:58:26,030 --> 00:58:32,530
This is the water and air connection which
you have to hook into your LCBG.

759
00:58:32,530 --> 00:58:34,690
And these are the arms that you have to get
into.

760
00:58:34,690 --> 00:58:41,690
And the problem in the design here is your
shoulders are wider than your chest.

761
00:58:46,859 --> 00:58:52,900
When you are actually inside the suit you
want the distance between these two arms to

762
00:58:52,900 --> 00:58:55,170
be conformal with your armpits.

763
00:58:55,170 --> 00:59:00,060
Because, if it is out here that cuts way down
on your mobility.

764
00:59:00,060 --> 00:59:04,650
But if it is too narrow you cannot get into
it.

765
00:59:04,650 --> 00:59:08,359
That is the basic design problem in this sort
of a suit.

766
00:59:08,359 --> 00:59:15,359
Now, the Russians have a rear entry suit that
doesn't have that problem.

767
00:59:16,020 --> 00:59:19,910
It is always a challenge and you really have
to push and struggle to get in.

768
00:59:19,910 --> 00:59:26,910
Eventually they wanted to design this suit
so that one person could get in by themselves,

769
00:59:28,480 --> 00:59:29,770
but it cannot be done.

770
00:59:29,770 --> 00:59:36,770
I mean you can get in like this but you just
cannot pull up the waist ring and attach it

771
00:59:37,310 --> 00:59:38,670
by yourself.

772
00:59:38,670 --> 00:59:40,510
Nobody has been able to do that.

773
00:59:40,510 --> 00:59:46,450
It is a great feeling of accomplishment when
you finally get inside.

774
00:59:46,450 --> 00:59:50,220
Then you put your helmet on.

775
00:59:50,220 --> 00:59:53,790
Now you're starting to see what we are dealing
with because we have to take all this stuff

776
00:59:53,790 --> 00:59:58,010
outside in addition to the tools that are
already outside.

777
00:59:58,010 --> 01:00:00,910
These are the plugs which we put the mini
work station.

778
01:00:00,910 --> 01:00:07,910
We haven't put it on quite yet but it is just
a whole bunch of equipment which you have

779
01:00:08,510 --> 01:00:10,230
to manage.

780
01:00:10,230 --> 01:00:16,980
At this point we purge the suit with an oxygen
flow.

781
01:00:16,980 --> 01:00:23,980
Now, remember, we are at an atmospheric pressure,
or almost an atmospheric pressure, I will

782
01:00:25,340 --> 01:00:31,070
get into that later, of pure oxygen, so that
also puts very serious flammability constraints.

783
01:00:31,070 --> 01:00:35,670
Although, when you go outside, you are only
at 4 psi.

784
01:00:35,670 --> 01:00:38,619
When you are inside here you are at the full
cabin pressure.

785
01:00:38,619 --> 01:00:44,180
Actually, in order to do your leap check you
have to go to 4 psi above cabin pressure.

786
01:00:44,180 --> 01:00:50,030
You are actually working at above one atmosphere
of pressure of pure oxygen, so that is a very

787
01:00:50,030 --> 01:00:54,040
serious flammability design constraint.

788
01:00:54,040 --> 01:01:01,040
And we have to sit and breathe pure oxygen
then for about 40 minutes to get the nitrogen

789
01:01:01,880 --> 01:01:02,670
out of our blood.

790
01:01:02,670 --> 01:01:06,810
And, again, I will be discussing this whole
atmospheric and bends problem.

791
01:01:06,810 --> 01:01:13,560
But, if you don't, when you drop down to 4
psi, the nitrogen in your blood bubbles out

792
01:01:13,560 --> 01:01:20,560
and you get the bends, just like a diver who
comes up too fast from a dive.

793
01:01:21,180 --> 01:01:25,540
Just one or two pictures of what went on outside.

794
01:01:25,540 --> 01:01:27,560
There is Hubble.

795
01:01:27,560 --> 01:01:29,099
I was changing some fuels there.

796
01:01:29,099 --> 01:01:31,609
It was kind of neat working underneath the
solar panel.

797
01:01:31,609 --> 01:01:34,940
Those were the old ones which we took off
and replaced the next day.

798
01:01:34,940 --> 01:01:39,460
But you have to be really careful because
you don't want to bang against it.

799
01:01:39,460 --> 01:01:44,470
And, of course, you cannot see above your
head, so we always have other people looking

800
01:01:44,470 --> 01:01:44,760
at us.

801
01:01:44,760 --> 01:01:49,640
This is the kind of situation where if you
had a little heads up display where you could

802
01:01:49,640 --> 01:01:53,960
get this sort of a view to show what you're
really doing it would really improve your

803
01:01:53,960 --> 01:01:55,140
situational awareness.

804
01:01:55,140 --> 01:01:58,869
But, at the moment, we don't have that.

805
01:01:58,869 --> 01:02:04,140
It takes not just the people outside but the
people inside paying full attention, reading

806
01:02:04,140 --> 01:02:04,910
procedures.

807
01:02:04,910 --> 01:02:11,910
Historically, we carried all of our procedures
on a cuff checklist, like so.

808
01:02:14,680 --> 01:02:18,970
But the procedures for Hubble and some of
the other flights are so complex that you

809
01:02:18,970 --> 01:02:19,630
just cannot do it.

810
01:02:19,630 --> 01:02:24,250
So, nowadays, these are just emergency procedures.

811
01:02:24,250 --> 01:02:25,820
I will pass this around.

812
01:02:25,820 --> 01:02:31,490
I would like it back.

813
01:02:31,490 --> 01:02:32,210
Let's see.

814
01:02:32,210 --> 01:02:39,210
After putting in the new Wiff-Pick, ground
had to do some tests on it, so I got Claude

815
01:02:40,119 --> 01:02:41,950
to fly me out over the arm.

816
01:02:41,950 --> 01:02:46,099
And we had one of the old Lunar Hasselblad
cameras which they let us carry.

817
01:02:46,099 --> 01:02:53,099
Normally, we just use Nikons on the Shuttle,
but they let us take a Hasselblad.

818
01:02:53,660 --> 01:02:57,930
That gives a view of what the payload bay
looks like EVA.

819
01:02:57,930 --> 01:03:02,140
Here is Story over here working on one of
the other things.

820
01:03:02,140 --> 01:03:05,050
The Earth is not flat, don't worry about the
picture.

821
01:03:05,050 --> 01:03:12,050
I went around it many times.

822
01:03:12,270 --> 01:03:19,270
And, I mean, some parts of EVA, I really should
share it because it just gets really spectacular.

823
01:03:19,609 --> 01:03:25,140
This is about 50 feet, I don't know whether
to say above or below or whatever of the Shuttle,

824
01:03:25,140 --> 01:03:28,400
but you're just out there in the middle of
nowhere.

825
01:03:28,400 --> 01:03:31,400
And, at this point, I was the free-floater.

826
01:03:31,400 --> 01:03:35,119
One of the people is always attached to the
end of the arm, which is good when you have

827
01:03:35,119 --> 01:03:39,760
to move around big pieces of equipment because
now you can react the forces with your feet.

828
01:03:39,760 --> 01:03:46,119
When you are a free-floater either you're
in a foot restraint, which limits your mobility,

829
01:03:46,119 --> 01:03:51,960
or one hand has to actually be holding you
so that you can react forces.

830
01:03:51,960 --> 01:03:58,960
Of course, we are attached by a waste tether,
which is then attached to a long real of stainless

831
01:04:02,450 --> 01:04:02,940
steel.

832
01:04:02,940 --> 01:04:09,180
But you can set it so that the springiness
is taken out.

833
01:04:09,180 --> 01:04:14,650
And so I could basically, and I did from time
to time, must sort of let go.

834
01:04:14,650 --> 01:04:21,650
And it is a really neat feeling because once
you convince yourself that you're not going

835
01:04:21,660 --> 01:04:28,619
to fall down, which I'm enough of a physicist
to understand the orbital mechanics, but,

836
01:04:28,619 --> 01:04:33,869
nevertheless, the first time I let go it was
an interesting feeling.

837
01:04:33,869 --> 01:04:38,380
The thing is when you're holding onto something,
whether by your feet or your hands, of course

838
01:04:38,380 --> 01:04:44,910
the Shuttle is so much more massive that you
feel yourself physically related.

839
01:04:44,910 --> 01:04:46,450
You are controlled by the Shuttle.

840
01:04:46,450 --> 01:04:49,589
And so the Shuttle is your point of reference.

841
01:04:49,589 --> 01:04:53,410
Maybe the Shuttle is in orbit but you are
attached to the Shuttle.

842
01:04:53,410 --> 01:04:57,529
As soon as I let go, the physics totally changes.

843
01:04:57,529 --> 01:05:01,930
And it was really this transformation into
being a human satellite.

844
01:05:01,930 --> 01:05:04,220
I mean I really felt like I was a satellite
now.

845
01:05:04,220 --> 01:05:05,609
I wasn't attached to the Shuttle.

846
01:05:05,609 --> 01:05:11,520
And sometimes, if I could turn around before
I let go so I didn't see the Shuttle, it was

847
01:05:11,520 --> 01:05:15,500
really kind of neat, especially at night,
just sort of floating there and all the stars

848
01:05:15,500 --> 01:05:15,940
and everything.

849
01:05:15,940 --> 01:05:16,260
Yeah.

850
01:05:16,260 --> 01:05:22,060
Do they build in time for you to be able to
kind of do that kind of thing?

851
01:05:22,060 --> 01:05:24,240
No, they don't build in the time.

852
01:05:24,240 --> 01:05:31,240
But, like in this case, two days before on
Story's and my last EVA we had replaced -- Not

853
01:05:31,730 --> 01:05:33,109
replaced.

854
01:05:33,109 --> 01:05:34,720
These are the magnetometers up at the top.

855
01:05:34,720 --> 01:05:41,720
The gross maneuvering of Hubble is done by
reaction wheels, but the reaction wheels,

856
01:05:43,060 --> 01:05:46,500
when they get spinning too fast, you have
to be able to desaturate them so they have

857
01:05:46,500 --> 01:05:52,300
magnetic torquers, these long torque rods
which create a magnetic field.

858
01:05:52,300 --> 01:05:58,670
There are no jets on Hubble because it would
cause pollution of the optics, so you need

859
01:05:58,670 --> 01:06:04,849
magnetometers up at the top to sense the magnetic
field in order to operate the torquers.

860
01:06:04,849 --> 01:06:08,349
The magnetometers were never designed to be
replaced.

861
01:06:08,349 --> 01:06:09,609
They weren't supposed to fail.

862
01:06:09,609 --> 01:06:13,660
Well, both of them failed in the first couple
of years.

863
01:06:13,660 --> 01:06:18,950
We couldn't take them off so they designed
two new magnetometers that we could actually

864
01:06:18,950 --> 01:06:21,779
insert and bolt on, on top of the old ones.

865
01:06:21,779 --> 01:06:27,520
And then we took the electrical and data connections
and hooked them up.

866
01:06:27,520 --> 01:06:33,940
But I noticed on that day -- We were very
concerned with quality control.

867
01:06:33,940 --> 01:06:38,270
First of all, that we didn't break anything
that wasn't already broken but also to look

868
01:06:38,270 --> 01:06:45,029
for any signs of damage because, you know,
this was a telescope that was supposed to

869
01:06:45,029 --> 01:06:47,839
be maintained.

870
01:06:47,839 --> 01:06:51,910
We saw a little bit of paint chipping off
the outside of the old magnetometers.

871
01:06:51,910 --> 01:06:58,029
They were concerned that they might float
around and get into the optics.

872
01:06:58,029 --> 01:07:04,630
We went into the payload bay the next day,
the other EVA team, and they cut off some

873
01:07:04,630 --> 01:07:09,490
of this gold insulation material from one
of the thermal enclosures that some of the

874
01:07:09,490 --> 01:07:11,000
equipment was in.

875
01:07:11,000 --> 01:07:13,330
And I'm not supposed to stand in front.

876
01:07:13,330 --> 01:07:18,580
I keep forgetting that.

877
01:07:18,580 --> 01:07:24,500
We made those covers, and then we had to go
up and install them.

878
01:07:24,500 --> 01:07:31,500
But, actually, after we installed them then
the ground wanted photographic documentation.

879
01:07:34,180 --> 01:07:35,089
We took pictures.

880
01:07:35,089 --> 01:07:40,180
And then the crew inside got their telephoto
lenses and they took a lot of pictures.

881
01:07:40,180 --> 01:07:44,500
And then they got the television camera on
the end of the arm to take pictures.

882
01:07:44,500 --> 01:07:49,930
And so, during all that time, you do have
a little bit of free time just to sort of

883
01:07:49,930 --> 01:07:51,050
enjoy the environment.

884
01:07:51,050 --> 01:07:53,960
It would be a shame not to because it is such
a spectacular place.

885
01:07:53,960 --> 01:07:54,359
Yeah.

886
01:07:54,359 --> 01:08:00,490
How do you work when there is not light when
you're on the dark side.

887
01:08:00,490 --> 01:08:03,660
Let me turn the laser pointer on here.

888
01:08:03,660 --> 01:08:05,910
Oh, no, what did I do?

889
01:08:05,910 --> 01:08:12,910
That is a good time for a break, right?

890
01:08:13,160 --> 01:08:18,179
Take a two-minute break.

891
01:08:18,179 --> 01:08:24,439
And then, of course, when the sun rises you
know it so you can turn your lights off.

892
01:08:24,439 --> 01:08:26,670
OK.

893
01:08:26,670 --> 01:08:33,670
I talked about the necessity of doing a nitrogen
purge and pre-breathing oxygen to get the

894
01:08:34,339 --> 01:08:35,429
nitrogen out of your blood.

895
01:08:35,429 --> 01:08:42,158
This turns out to be an interesting systems
problem because it doesn't just affect the

896
01:08:42,158 --> 01:08:47,238
suit, it affects the spacecraft.

897
01:08:47,238 --> 01:08:51,279
Those of you who were here at the beginning
saw I was blowing up a balloon which unfortunately

898
01:08:51,279 --> 01:08:52,670
popped.

899
01:08:52,670 --> 01:08:59,670
It was only to make the point that you can
look at a spacesuit, the arms and legs, cylindrical.

900
01:08:59,959 --> 01:09:02,219
It is like one of those balloons.

901
01:09:02,219 --> 01:09:08,118
And when you try to bend the balloon it doesn't
like to stay bent because you are compressing

902
01:09:08,118 --> 01:09:14,389
the gas and you're doing elastic work on the
material of the balloon and it wants to snap

903
01:09:14,389 --> 01:09:14,729
back.

904
01:09:14,729 --> 01:09:17,190
And spacesuits basically work the same way.

905
01:09:17,190 --> 01:09:23,618
The old-fashioned pressure suits that test
pilots used to wear, which were the genesis

906
01:09:23,618 --> 01:09:27,399
of the original Mercury suits, they basically
stiffen you.

907
01:09:27,399 --> 01:09:31,448
And, in fact, the launch entry suits that
we use on the Shuttle are not designed for

908
01:09:31,448 --> 01:09:32,259
joint mobility.

909
01:09:32,259 --> 01:09:35,109
They are just pressurized.

910
01:09:35,109 --> 01:09:41,599
And we do a pressure check before the mission
when we're getting suited up.

911
01:09:41,599 --> 01:09:47,029
And they blow it up and you just go like that.

912
01:09:47,029 --> 01:09:50,499
You can move a little bit, you know, enough
so that if you're sitting in your seat with

913
01:09:50,499 --> 01:09:56,820
a seatbelt holding you in form so that your
waist is bent, you can move your arms enough

914
01:09:56,820 --> 01:09:57,789
to get to the controls.

915
01:09:57,789 --> 01:10:01,420
But I certainly wouldn't want to try and go
out and do any useful work in that.

916
01:10:01,420 --> 01:10:08,420
It has really been an extraordinary design
process that people have been able to develop

917
01:10:10,019 --> 01:10:13,949
spacesuits with articulating joints.

918
01:10:13,949 --> 01:10:19,570
I mean it is certainly not like walking around
and doing things just with your body, but

919
01:10:19,570 --> 01:10:24,239
it is amazing how flexible spacesuits are.

920
01:10:24,239 --> 01:10:30,159
And it is a continual challenge to develop,
particularly for the gloves.

921
01:10:30,159 --> 01:10:34,440
And, when we get back to the moon, to have
legs that can actually walk in so that you

922
01:10:34,440 --> 01:10:36,179
don't have to hop around all the time.

923
01:10:36,179 --> 01:10:38,269
Although, there are times when that is good,
too.

924
01:10:38,269 --> 01:10:45,269
But, in any case, the stiffness of the suit,
because it turns out that most of the stiffness

925
01:10:47,139 --> 01:10:54,139
comes from compressing the gas, you want to
try, first of all, to build articulated joints

926
01:10:54,309 --> 01:10:57,190
that don't change their volume.

927
01:10:57,190 --> 01:11:02,449
And, actually, people have designed metallic
suits that look like Robby the Robot.

928
01:11:02,449 --> 01:11:07,010
So, they truly are zero delta volume suits.

929
01:11:07,010 --> 01:11:10,699
The problem is they are very heavy and there
are other problems with metallic suits.

930
01:11:10,699 --> 01:11:15,760
And I don't have time to go into that.

931
01:11:15,760 --> 01:11:21,260
Given that you're going to have some volume
change, the amount of work that you do is

932
01:11:21,260 --> 01:11:24,699
thermodynamically pressure times volume.

933
01:11:24,699 --> 01:11:27,309
You are going to have a delta V.

934
01:11:27,309 --> 01:11:29,389
You want to reduce the pressure.

935
01:11:29,389 --> 01:11:35,800
The lower your suit pressure, the easier it
is to bend.

936
01:11:35,800 --> 01:11:42,679
Basically, you don't want to fill your suit
with any gas that you don't really need.

937
01:11:42,679 --> 01:11:48,630
We certainly don't need nitrogen to stay alive,
not on a short-term basis, so we fill the

938
01:11:48,630 --> 01:11:52,099
suit with oxygen.

939
01:11:52,099 --> 01:11:57,820
And we run it at about 4.3 psi for the Shuttle.

940
01:11:57,820 --> 01:12:04,820
This is just historically Mercury, Gemini
and Apollo, the suit pressure was a little

941
01:12:05,699 --> 01:12:06,079
bit lower.

942
01:12:06,079 --> 01:12:13,079
Doctors felt, after doing calculations, what
you're really interested in is the partial

943
01:12:14,469 --> 01:12:16,699
pressure of oxygen in your blood.

944
01:12:16,699 --> 01:12:19,329
And they wanted a little bit more margin.

945
01:12:19,329 --> 01:12:23,159
Since the Shuttle was supposed to be operational
this and operational that, they wanted a little

946
01:12:23,159 --> 01:12:25,869
bit more margin.

947
01:12:25,869 --> 01:12:30,429
And so we bumped up the suit pressure a little
bit.

948
01:12:30,429 --> 01:12:37,199
Mercury, Gemini and Apollo cabin was 100%
oxygen at the same pressure so that you didn't

949
01:12:37,199 --> 01:12:40,340
have to worry about pre-breathing.

950
01:12:40,340 --> 01:12:46,329
In Skylab, it was not pure oxygen but it was
a high enough oxygen that, again, they didn't

951
01:12:46,329 --> 01:12:47,599
have to worry about pre-breathe.

952
01:12:47,599 --> 01:12:54,599
It wasn't until we went to the Shuttle, which
typically the Shuttle is at 14.7 or 100 kilopascals

953
01:12:58,869 --> 01:13:02,280
normal atmospheric pressure.

954
01:13:02,280 --> 01:13:07,840
If we know we are going to be doing a lot
of EVAs, and I will talk about this later,

955
01:13:07,840 --> 01:13:13,849
what we do is we drop the overall cabin pressure,
but we keep the partial pressure of oxygen

956
01:13:13,849 --> 01:13:18,699
the same so you end up bumping up the oxygen
concentration.

957
01:13:18,699 --> 01:13:21,099
We don't do that with the ISS.

958
01:13:21,099 --> 01:13:28,099
The decision was made by the life scientists
that since they wanted to study biology on

959
01:13:28,670 --> 01:13:35,639
the Space Station and all of our database
is at one atmosphere, that if they took the

960
01:13:35,639 --> 01:13:42,479
Space Station down to 10.2 psi basically it
would invalidate all of their life science

961
01:13:42,479 --> 01:13:44,369
research.

962
01:13:44,369 --> 01:13:47,559
So, the Station was only designed for one
atmosphere.

963
01:13:47,559 --> 01:13:51,820
The operational people, when they started
to talk about how much EVA was going to be

964
01:13:51,820 --> 01:13:58,300
involved in building and maintaining the Space
Station, the astronauts said this is crazy.

965
01:13:58,300 --> 01:14:05,300
And you will see the impact of this later.

966
01:14:06,889 --> 01:14:08,699
This is just looking in the future.

967
01:14:08,699 --> 01:14:14,570
These are decisions that are going have to
be made for future space systems, and they

968
01:14:14,570 --> 01:14:17,860
are looking at a lower working pressure.

969
01:14:17,860 --> 01:14:23,559
And you will see why as I go through this
presentation.

970
01:14:23,559 --> 01:14:28,119
I think I'm not going to go through those
charts.

971
01:14:28,119 --> 01:14:29,699
Again, this is a system.

972
01:14:29,699 --> 01:14:33,570
So, you are affecting a great many different
things.

973
01:14:33,570 --> 01:14:37,659
Let's see.

974
01:14:37,659 --> 01:14:44,659
Which is the laser here?

975
01:14:44,769 --> 01:14:49,300
There we go.

976
01:14:49,300 --> 01:14:56,300
One of the interesting things here with EVA,
just like in any ECLS system, is that the

977
01:14:57,539 --> 01:15:03,150
human body becomes one of your subsystems
that you have to take care of.

978
01:15:03,150 --> 01:15:07,650
And, in many cases, we don't have a whole
lot of design flexibility with our bodies

979
01:15:07,650 --> 01:15:11,229
because they come predesigned.

980
01:15:11,229 --> 01:15:15,079
So, we have to deal with that.

981
01:15:15,079 --> 01:15:22,079
We have all of the physiology, the bends.

982
01:15:22,639 --> 01:15:22,889
Materials.
I talked about flammability in a pure oxygen
environment.

983
01:15:25,820 --> 01:15:32,820
I talked about the constraints of microgravity
and partial gravity physiology studies in

984
01:15:33,170 --> 01:15:33,829
the ISS.

985
01:15:33,829 --> 01:15:40,829
Of course, NASA has decided that we don't
need to do that anymore.

986
01:15:41,190 --> 01:15:44,440
And, I guess, our international partners are
still going to want to do this.

987
01:15:44,440 --> 01:15:47,449
In any case, the Station is designed.

988
01:15:47,449 --> 01:15:53,809
The cooling we talked about, I think, in the
ECLA section lecture, the fact that if you

989
01:15:53,809 --> 01:15:58,340
drop your cabin pressure now you've got to
pump more air for all the air cooled things.

990
01:15:58,340 --> 01:16:05,340
And if you really want a design for a variable
cabin pressure then that flows over into the

991
01:16:07,959 --> 01:16:14,959
cooling requirements, more water cooling,
different fan requirements and so on.

992
01:16:15,849 --> 01:16:17,079
And it goes on.

993
01:16:17,079 --> 01:16:24,079
If you are going to do multiple EVAs, what
you're really interested in, when you're looking

994
01:16:26,840 --> 01:16:33,300
at efficiency, is what we call EVA Work Efficiency
Index.

995
01:16:33,300 --> 01:16:40,300
It is the total amount of time involved in
preparing for and carrying out an EVA, the

996
01:16:40,380 --> 01:16:43,979
ratio of that to the actual useful working
time you get outside.

997
01:16:43,979 --> 01:16:49,619
And the more time you have to spend breathing
pure oxygen to denitrogenate your blood, that

998
01:16:49,619 --> 01:16:52,619
is taking away from your overall work efficiency.

999
01:16:52,619 --> 01:16:58,159
When we do tests on the ground and we start
out at normal sea level pressure and we want

1000
01:16:58,159 --> 01:17:05,159
to go down to 4.3 psi pure oxygen, we actually
have to do a four hour nitrogen purge.

1001
01:17:09,199 --> 01:17:14,760
We have to just sit in the suit or stand in
the suit for four hours, this is in the EVA

1002
01:17:14,760 --> 01:17:18,409
test chambers, before we actually can go down
to pressure.

1003
01:17:18,409 --> 01:17:22,749
If you want to get an eight hour work day
of EVA, that is just unacceptable.

1004
01:17:22,749 --> 01:17:28,110
And that is why they made the decision to
lower the Shuttle's cabin pressure.

1005
01:17:28,110 --> 01:17:30,679
Then you only have to do about a 40 minute
EVA.

1006
01:17:30,679 --> 01:17:36,459
And I have some of the specific numbers on
that later.

1007
01:17:36,459 --> 01:17:41,289
As I say, just the review here is that we
do have this capability on the Shuttle.

1008
01:17:41,289 --> 01:17:44,949
We don't have it on the Station.

1009
01:17:44,949 --> 01:17:49,219
They have figured out a few ways to make the
denitrogenation process a little bit more

1010
01:17:49,219 --> 01:17:54,880
efficient on the Station, but it is still
a big overhead hit.

1011
01:17:54,880 --> 01:18:01,840
And we are very concerned for the future because
EVA is not just an afterthought when you're

1012
01:18:01,840 --> 01:18:04,380
going to be exploring on the Moon or Mars.

1013
01:18:04,380 --> 01:18:07,829
You are going there basically to do EVA.

1014
01:18:07,829 --> 01:18:10,690
Otherwise, why bother?

1015
01:18:10,690 --> 01:18:13,209
We have got to deal with this.

1016
01:18:13,209 --> 01:18:18,699
Here is the basic physiology that we are dealing
with.

1017
01:18:18,699 --> 01:18:25,699
Oxygen percentage on the abscissa, total pressure
on the ordinate and all different units.

1018
01:18:26,479 --> 01:18:33,479
Millimeters of mercury, psi, and I think now
people use kilopascals, which I don't really

1019
01:18:34,639 --> 01:18:35,329
relate to.

1020
01:18:35,329 --> 01:18:39,820
But I know about 100 kilopascals is about
one atmosphere, so luckily that makes it easy.

1021
01:18:39,820 --> 01:18:46,820
Normally, we are at one atmosphere 20% or
21% oxygen, we are up here, and this is the

1022
01:18:49,829 --> 01:18:53,940
normal sea level equivalent.

1023
01:18:53,940 --> 01:19:00,940
You start dropping the pressure and you have
to increase the percentage of oxygen.

1024
01:19:02,010 --> 01:19:09,010
There is a maximum level of breathing oxygen
at pressure oxygen toxicity because oxygen

1025
01:19:11,760 --> 01:19:16,320
is almost totally absorbed through your alveoli.

1026
01:19:16,320 --> 01:19:23,320
And normally our alveoli stay inflated because
we have 80% nitrogen which is only very reluctantly

1027
01:19:24,550 --> 01:19:25,070
absorbed.

1028
01:19:25,070 --> 01:19:28,969
I mean it does get through, that is how it
gets into our blood and so on, but it is a

1029
01:19:28,969 --> 01:19:30,409
much slower transport.

1030
01:19:30,409 --> 01:19:31,909
But oxygen gets right through.

1031
01:19:31,909 --> 01:19:38,909
And if you breathe pure oxygen for a long
time you can really hurt your lungs and it

1032
01:19:40,959 --> 01:19:44,010
can be lethal at a certain point.

1033
01:19:44,010 --> 01:19:49,119
We actually don't have any good physiological
data.

1034
01:19:49,119 --> 01:19:51,789
I was down in Houston last week at a big EVA
conference.

1035
01:19:51,789 --> 01:19:53,760
That is why we didn't have class on Tuesday.

1036
01:19:53,760 --> 01:20:00,719
They were talking about what about long-term
planetary EVAs, even at 4 psi pure oxygen,

1037
01:20:00,719 --> 01:20:03,329
is that going to be harmful to health?

1038
01:20:03,329 --> 01:20:04,079
We honestly don't know.

1039
01:20:04,079 --> 01:20:10,219
I mean that is an active area which needs
research.

1040
01:20:10,219 --> 01:20:15,689
On the other side, of course you get into
hypoxia which you have all heard of.

1041
01:20:15,689 --> 01:20:19,579
You get it when you go up on Mount Everest
and so on.

1042
01:20:19,579 --> 01:20:26,579
So, you've got a boundary that you have to
work in.

1043
01:20:27,159 --> 01:20:31,939
Now, this is sort of where things have fallen.

1044
01:20:31,939 --> 01:20:34,939
The blue line is the hypoxic boundary.

1045
01:20:34,939 --> 01:20:39,659
The green line is normal oxygen.

1046
01:20:39,659 --> 01:20:45,820
When we were using pure oxygen spacecraft
environments, we were well above that.

1047
01:20:45,820 --> 01:20:48,090
You would like to stay as close as possible.

1048
01:20:48,090 --> 01:20:55,090
With Shuttle EVA, we moved a little bit closer
to hypoxic, but we're still in a physiologically

1049
01:20:55,300 --> 01:21:02,300
perfectly reasonable environment.

1050
01:21:02,639 --> 01:21:04,889
Decompression sickness, just a quick review.

1051
01:21:04,889 --> 01:21:06,030
Any scuba divers here?

1052
01:21:06,030 --> 01:21:09,489
You are all familiar with this.

1053
01:21:09,489 --> 01:21:16,489
There are various levels of decompression
sickness anywhere from just a mild tingling

1054
01:21:17,139 --> 01:21:24,139
of the skin to joint pain to phase three DCS
where you get central nervous system impairment

1055
01:21:25,489 --> 01:21:32,489
which can actually cause death, so you don't
want to mess around with it.

1056
01:21:36,380 --> 01:21:39,059
People refer to this famous R value.

1057
01:21:39,059 --> 01:21:40,590
You run into this all the time.

1058
01:21:40,590 --> 01:21:47,249
What you are really interested in is what
is the ratio between the actual partial pressure

1059
01:21:47,249 --> 01:21:52,900
of nitrogen in your blood compared to your
suit pressure?

1060
01:21:52,900 --> 01:21:57,090
And this over here shows this R value.

1061
01:21:57,090 --> 01:22:03,550
If you are down at one the nitrogen isn't
going to bubble out at all so you have no

1062
01:22:03,550 --> 01:22:05,709
incidence of bends.

1063
01:22:05,709 --> 01:22:12,579
VGE, venous gas emboli.

1064
01:22:12,579 --> 01:22:19,579
And then, as the R value increases, the dotted
line gas emboli, that just means you have

1065
01:22:20,110 --> 01:22:20,909
bubbles forming.

1066
01:22:20,909 --> 01:22:26,099
DCS means actual symptoms of bends.

1067
01:22:26,099 --> 01:22:30,300
And then grade three DCS which is very serious
indeed.

1068
01:22:30,300 --> 01:22:37,300
The way they make these measurements, they
have these large physiological studies where

1069
01:22:37,389 --> 01:22:42,329
they actually get people to volunteer to go
through these pumped down protocols.

1070
01:22:42,329 --> 01:22:48,659
And then they actually put sensitive microphones
and ultrasound things that can actually hear

1071
01:22:48,659 --> 01:22:51,249
the bubbles as they move around your veins.

1072
01:22:51,249 --> 01:22:56,070
I have never been able to figure out why anybody
would volunteer for these experiments.

1073
01:22:56,070 --> 01:22:59,739
I take my hat off to them.

1074
01:22:59,739 --> 01:23:06,300
Because the only way you build up this data
is that some people actually do get the bends

1075
01:23:06,300 --> 01:23:07,170
from these experiments.

1076
01:23:07,170 --> 01:23:12,849
And, of course, they have hyperbaric chambers
which, as soon as there are any symptoms,

1077
01:23:12,849 --> 01:23:17,079
they put them right into the chamber and pump
them to pressure and it goes away.

1078
01:23:17,079 --> 01:23:20,439
And I don't think that they have lost any
volunteers.

1079
01:23:20,439 --> 01:23:26,400
Like I say, that is not something I am going
to volunteer for.

1080
01:23:26,400 --> 01:23:31,360
Other factors, this is something that becomes
important.

1081
01:23:31,360 --> 01:23:36,630
It turns out that the amount of time you spend
at reduced pressure is important.

1082
01:23:36,630 --> 01:23:37,860
Also exercise.

1083
01:23:37,860 --> 01:23:42,739
It turns out that the more you exercise, maybe
it makes sense, you're moving your joints

1084
01:23:42,739 --> 01:23:45,469
around, but the bubbles come out.

1085
01:23:45,469 --> 01:23:48,579
Actually, what they have started to do on
the Space Station, since we cannot go to a

1086
01:23:48,579 --> 01:23:55,579
reduced cabin, that while they are breathing
oxygen for the first hour or so they do very

1087
01:23:55,590 --> 01:24:01,849
exhaustive exercise, both upper and lower
body on an exercise bike with arm exercise

1088
01:24:01,849 --> 01:24:02,280
as well.

1089
01:24:02,280 --> 01:24:09,280
To try to drive away as much of the oxygen
early on in the decompression preparation

1090
01:24:10,570 --> 01:24:11,429
as you can.

1091
01:24:11,429 --> 01:24:14,219
OK.

1092
01:24:14,219 --> 01:24:16,900
Where does that put us?

1093
01:24:16,900 --> 01:24:22,079
As I said, the more nitrogen you have in your
blood to start out with, the longer a pre-breathe

1094
01:24:22,079 --> 01:24:28,829
you are going to have to do before you can
go out.

1095
01:24:28,829 --> 01:24:32,949
These are the normoxic and hypoxic lines,
which I showed you before.

1096
01:24:32,949 --> 01:24:39,139
And then these are the contours of the amount
of time you have to pre-breathe.

1097
01:24:39,139 --> 01:24:46,139
Remember, I told you if you are at one atmosphere,
20% oxygen, your pre-breathe time is 240 minutes,

1098
01:24:48,139 --> 01:24:49,409
four hours.

1099
01:24:49,409 --> 01:24:53,499
This is to get yourself down to an R value
of 1.65.

1100
01:24:53,499 --> 01:25:00,499
This is not 100% safe because, remember, at
1.65, there still is a 25% incidence of DCS.

1101
01:25:08,650 --> 01:25:15,650
Now, the interesting thing, these are the
statistics that come from the laboratory trials,

1102
01:25:15,840 --> 01:25:21,760
we have never had a reported case of bends
during EVAs.

1103
01:25:21,760 --> 01:25:25,949
And people are not quite sure why.

1104
01:25:25,949 --> 01:25:30,820
Some people suspect that maybe even if an
astronaut is getting joint pain they are not

1105
01:25:30,820 --> 01:25:37,539
going to report it because maybe that would
prevent you from doing another EVA.

1106
01:25:37,539 --> 01:25:42,769
I mean there are enough other pains that you
undergo in just using a spacesuit that maybe

1107
01:25:42,769 --> 01:25:44,170
you don't even notice it.

1108
01:25:44,170 --> 01:25:48,579
You feel a problem in your joints or your
fingers and you say oh, damn, my gloves don't

1109
01:25:48,579 --> 01:25:53,789
fit right or something like that.

1110
01:25:53,789 --> 01:25:55,550
I have another slide mentioning this later.

1111
01:25:55,550 --> 01:26:02,550
There is some suspicion that weightlessness
may have an impact, which means that the bends

1112
01:26:04,179 --> 01:26:10,999
susceptibility on the Moon or on Mars may
actually be greater than it is in weightlessness.

1113
01:26:10,999 --> 01:26:15,579
We just don't know.

1114
01:26:15,579 --> 01:26:18,860
Here is where we have gotten to on the Shuttle
EVA.

1115
01:26:18,860 --> 01:26:25,389
Again, this is no pre-breathe, this is one
hour pre-breathe, so we are at about 40 minutes

1116
01:26:25,389 --> 01:26:26,329
on the Shuttle.

1117
01:26:26,329 --> 01:26:30,189
That is where we are.

1118
01:26:30,189 --> 01:26:33,630
Now, this is a design problem.

1119
01:26:33,630 --> 01:26:35,260
How are we going to design the CEV?

1120
01:26:35,260 --> 01:26:40,039
How are we going to design the equipment,
the habitats that we are going to use on the

1121
01:26:40,039 --> 01:26:43,519
Moon and Mars?

1122
01:26:43,519 --> 01:26:45,539
Now we're talking about surface exploration.

1123
01:26:45,539 --> 01:26:52,539
And, as I said, there is a lot of uncertainty
about the affect of gravity.

1124
01:26:52,780 --> 01:26:58,670
But we suspect that it may be more bends inducing
than weightlessness.

1125
01:26:58,670 --> 01:27:05,670
And so what they are doing for safety and
conservatism is instead of using the R value

1126
01:27:07,019 --> 01:27:14,019
of 1.65, which we use on the Shuttle, they
are taking it down to about 1.3, 1.4.

1127
01:27:18,239 --> 01:27:19,499
Now, what does that do?

1128
01:27:19,499 --> 01:27:22,349
Here is 1.4, 1.3.

1129
01:27:22,349 --> 01:27:27,249
Where does that put the Shuttle EVA we now
would have to get down to that R value?

1130
01:27:27,249 --> 01:27:31,530
We have got a two hour pre-breathe.

1131
01:27:31,530 --> 01:27:37,769
To get down to 1.3, we have got a 2.5 hour
pre-breathe.

1132
01:27:37,769 --> 01:27:42,499
And this is with the normal spacesuit at 4.3
psi.

1133
01:27:42,499 --> 01:27:46,369
We are heading an operational problem.

1134
01:27:46,369 --> 01:27:51,949
If you want to go out on your geology traverse
on the Moon, you have got to depressurize,

1135
01:27:51,949 --> 01:27:53,539
denitrogenate for 2, 2.5 hours.

1136
01:27:53,539 --> 01:27:55,110
I don't think so.

1137
01:27:55,110 --> 01:27:56,959
But what are we going to do?

1138
01:27:56,959 --> 01:28:03,959
Well, if you increase the suit pressure now
the R value, at a given level of nitrogen,

1139
01:28:06,510 --> 01:28:07,739
goes down.

1140
01:28:07,739 --> 01:28:14,739
And so at 6 psi, even for an R of 1.3, you
are in the zero pre-breathe range, which would

1141
01:28:17,610 --> 01:28:19,269
be great.

1142
01:28:19,269 --> 01:28:24,599
People have suggested, well, maybe we should
build a variable pressure suit so that you

1143
01:28:24,599 --> 01:28:29,360
could go out at 6 psi, sort of get things
set up.

1144
01:28:29,360 --> 01:28:35,360
And then all that time counts towards your
denitrogenation so maybe then after two hours

1145
01:28:35,360 --> 01:28:37,360
into your EVA now you can drop your pressure.

1146
01:28:37,360 --> 01:28:41,809
And now, if you have any things where you
need more dexterity, you will be OK.

1147
01:28:41,809 --> 01:28:48,809
But the pressure control system in a spacesuit
is a very complex undertaking.

1148
01:28:49,959 --> 01:28:52,769
The Russians do have a dual pressure suit.

1149
01:28:52,769 --> 01:28:57,380
They never used the lower pressure, to my
knowledge.

1150
01:28:57,380 --> 01:29:00,789
And it is a big hit to try to design this
into the suit.

1151
01:29:00,789 --> 01:29:03,959
And, of course, to design a suit to operate
at a higher pressure.

1152
01:29:03,959 --> 01:29:10,289
The Russians work at about 5 psi, but it means
your suit is less flexible, heavier and is

1153
01:29:10,289 --> 01:29:16,209
just going the opposite direction from the
desire to accomplish useful work, which is

1154
01:29:16,209 --> 01:29:19,439
why you are putting on the spacesuit in the
first place.

1155
01:29:19,439 --> 01:29:23,689
This is what we are working against.

1156
01:29:23,689 --> 01:29:25,030
Again, we have got a systems problem.

1157
01:29:25,030 --> 01:29:26,800
It is not just the pressure.

1158
01:29:26,800 --> 01:29:30,999
It is the oxygen.

1159
01:29:30,999 --> 01:29:37,999
In Skylab, in Apollo, because you were working
in a pure oxygen environment, now, of course,

1160
01:29:39,229 --> 01:29:42,780
we're talking about what is the pressure going
to be in the cabin.

1161
01:29:42,780 --> 01:29:48,119
You want to keep the cabin at a higher oxygen
environment.

1162
01:29:48,119 --> 01:29:50,889
Your material selection is highly limited.

1163
01:29:50,889 --> 01:29:54,510
As it says, they tended to use a lot of metallic
materials.

1164
01:29:54,510 --> 01:29:56,599
Well, what do we know about metals?

1165
01:29:56,599 --> 01:29:58,729
Particularly aluminum.

1166
01:29:58,729 --> 01:30:03,229
First of all, aluminum will burn at 100% oxygen.

1167
01:30:03,229 --> 01:30:08,749
But your cabin, even if it is not 100% oxygen,
you are going to have a lot of metallic material.

1168
01:30:08,749 --> 01:30:15,749
Well, metal, when you're dealing with radiation,
you hit metal, aluminum or even higher atomic

1169
01:30:19,420 --> 01:30:24,039
number metals with primary cosmic rays and
you get spallation.

1170
01:30:24,039 --> 01:30:26,409
You produce a lot of secondary particles.

1171
01:30:26,409 --> 01:30:30,639
And you end up with actually more radiation
than you would have gotten if you had just

1172
01:30:30,639 --> 01:30:32,869
gotten hit by the incident cosmic ray.

1173
01:30:32,869 --> 01:30:37,699
What you really prefer is to have low atomic
number.

1174
01:30:37,699 --> 01:30:39,579
Hydrogen is best.

1175
01:30:39,579 --> 01:30:42,400
Water, hydrogen, oxygen and so forth.

1176
01:30:42,400 --> 01:30:48,999
If you are forced to increase the metallic
content of your spacecraft because of the

1177
01:30:48,999 --> 01:30:55,999
oxygen flammability problems now you are going
in the wrong direction for radiation protection

1178
01:30:58,429 --> 01:31:04,309
which becomes an issue when you're dealing
with long duration stays on the Moon, interplanetary

1179
01:31:04,309 --> 01:31:06,380
transport and so on.

1180
01:31:06,380 --> 01:31:08,139
So, it is all interrelated.

1181
01:31:08,139 --> 01:31:13,769
You cannot change one thing without changing
the other.

1182
01:31:13,769 --> 01:31:14,030
Flammability.

1183
01:31:14,030 --> 01:31:15,300
Well, we have been talking about that.

1184
01:31:15,300 --> 01:31:18,079
I won't stay on that.

1185
01:31:18,079 --> 01:31:24,249
But, again, it is very dependent on oxygen.

1186
01:31:24,249 --> 01:31:27,010
Oxygen restricts the use of non-metallic materials.

1187
01:31:27,010 --> 01:31:32,170
But nonmetallic materials are what we would
like to use from a radiation point of view.

1188
01:31:32,170 --> 01:31:38,189
You would like to have a lot of hydrocarbons,
you know, polyethylene plastic in your spacecraft

1189
01:31:38,189 --> 01:31:43,070
because they absorb cosmic rays.

1190
01:31:43,070 --> 01:31:49,820
But, in any case, it is pretty well agreed
that we never want to go above 30% oxygen.

1191
01:31:49,820 --> 01:31:55,189
It just becomes too restrictive on the types
of materials we can use.

1192
01:31:55,189 --> 01:31:56,840
That is going to be a design constraint.

1193
01:31:56,840 --> 01:32:03,840
And, remember, we are aiming towards a systems
level design of our long duration space habitats

1194
01:32:05,590 --> 01:32:07,039
which are EVA compatible.

1195
01:32:07,039 --> 01:32:09,539
30% oxygen.

1196
01:32:09,539 --> 01:32:11,260
Now we are back to this.

1197
01:32:11,260 --> 01:32:13,170
Now we can draw a red line.

1198
01:32:13,170 --> 01:32:15,599
And we have got to stay on the left of that
line.

1199
01:32:15,599 --> 01:32:19,949
We have got to stay above the blue hypoxic
line.

1200
01:32:19,949 --> 01:32:26,949
Now, also remember that we have got these
pre-breathe lines.

1201
01:32:27,429 --> 01:32:31,849
Let's say we are going to limit pre-breathe
to no more than one hour.

1202
01:32:31,849 --> 01:32:35,869
Well, we are cutting down on our design space
here.

1203
01:32:35,869 --> 01:32:40,110
We have got the oxygen flammability which
is cutting off to the right.

1204
01:32:40,110 --> 01:32:44,239
We have got the hypoxic limit which is cutting
off in this direction.

1205
01:32:44,239 --> 01:32:47,869
And we have got the pre-breathe limit which
is cutting off there.

1206
01:32:47,869 --> 01:32:54,869
We are kind of in a, I won't call it a box,
a rather small triangle.

1207
01:32:57,349 --> 01:33:03,869
Now, if we go to a 6 psi spacesuit, as I said,
we open up the design space a lot.

1208
01:33:03,869 --> 01:33:10,019
But at a price of flexibility, maneuverability
and the ability to do the things that we want

1209
01:33:10,019 --> 01:33:14,530
to do in the first place.

1210
01:33:14,530 --> 01:33:16,699
Where are we going to go with this?

1211
01:33:16,699 --> 01:33:19,340
As I say, it is an active area of research.

1212
01:33:19,340 --> 01:33:26,340
I cannot tell you what the answer is going
to be but it looks like they are going to

1213
01:33:30,719 --> 01:33:37,719
probably be going for 8 to 9 psi with an oxygen
concentration approaching 30%.

1214
01:33:39,249 --> 01:33:44,689
And that the CEV, from what I have been told,
is most likely going to be designed with a

1215
01:33:44,689 --> 01:33:48,939
variable pressure capability because it also
has to be able to dock with the Space Station

1216
01:33:48,939 --> 01:33:51,309
which means it has to be able to take one
atmosphere.

1217
01:33:51,309 --> 01:33:58,309
And also, because the CEV by itself is not
going to have an airlock, if you would have

1218
01:33:58,369 --> 01:34:03,689
to do an emergency EVA out of the CEV, for
whatever reason, you are going to have to

1219
01:34:03,689 --> 01:34:10,689
depressurize like we did back in the Gemini
days, or Apollo.

1220
01:34:10,820 --> 01:34:17,449
And, of course, that is going to affect the
design of all the other systems on the CEV

1221
01:34:17,449 --> 01:34:24,449
because they will have to be able to operate
from a vacuum all the way up to one atmosphere.

1222
01:34:28,420 --> 01:34:34,010
Just in the end, I hope what you have gotten
out of this is, again, we are trying to look

1223
01:34:34,010 --> 01:34:37,039
at things from a systems engineering point
of view.

1224
01:34:37,039 --> 01:34:43,619
And this is one big system where EVA cannot
be considered just on its own.

1225
01:34:43,619 --> 01:34:50,400
I gave an example of how it affects the RCS
system with Hubble.

1226
01:34:50,400 --> 01:34:54,409
Here it affects the environmental control
life support.

1227
01:34:54,409 --> 01:35:01,409
Flammability, radiation protection, it is
all linked together.

1228
01:35:02,639 --> 01:35:09,639
This was the recommendation that we came out
with, slightly below 9 psi pushing 30%.

1229
01:35:10,409 --> 01:35:17,409
But, as I said, there is a lot of research
that has to be done to understand the way

1230
01:35:17,610 --> 01:35:22,478
bends behave at partial gravity.

1231
01:35:22,478 --> 01:35:23,419
How we are going to do that?

1232
01:35:23,419 --> 01:35:30,070
I have no idea.

1233
01:35:30,070 --> 01:35:37,070
As I said, for the International Space Station,
we have to be able to go up to regular atmosphere.

1234
01:35:43,439 --> 01:35:48,429
We were making this presentation as part of
the study we were doing last year on CEV,

1235
01:35:48,429 --> 01:35:53,769
but it was so relevant to what we did here
that I didn't see any point in modifying it

1236
01:35:53,769 --> 01:35:54,419
for this class.

1237
01:35:54,419 --> 01:36:01,419
But we had to make these decisions on the
Shuttle based on similar calculations looking

1238
01:36:02,709 --> 01:36:03,959
at the design space.

1239
01:36:03,959 --> 01:36:10,079
The difference was with the Shuttle we were
using an R value of 1.6, 1.7.

1240
01:36:10,079 --> 01:36:14,860
And so we were able to get down to a 40 minute
pre-breathe.

1241
01:36:14,860 --> 01:36:21,189
What we do with the Shuttle is about the day
before you are going to do your first EVA

1242
01:36:21,189 --> 01:36:25,739
you actually drop the cabin pressure.

1243
01:36:25,739 --> 01:36:31,380
And when we had the lecture on environmental
control, remember there is a cabin pressure

1244
01:36:31,380 --> 01:36:35,309
controller at 14.7 and a pressure controller
at 8 psi.

1245
01:36:35,309 --> 01:36:41,519
But when they designed the Shuttle, nobody
was thinking about EVA or about this pre-breathe

1246
01:36:41,519 --> 01:36:41,800
time.

1247
01:36:41,800 --> 01:36:45,019
And so, there is no 10.2 controller.

1248
01:36:45,019 --> 01:36:46,459
We have to do that manually.

1249
01:36:46,459 --> 01:36:51,099
You drop it and then you add a little bit
of nitrogen or a little bit of oxygen, depending

1250
01:36:51,099 --> 01:36:54,669
on what the instrumentation tells you you
need.

1251
01:36:54,669 --> 01:37:01,559
And then there is a periodic maintenance which
you have to perform in order to keep the proper

1252
01:37:01,559 --> 01:37:07,320
gas concentrations.

1253
01:37:07,320 --> 01:37:11,209
And then we leave it down there for the duration
of all the EVAs.

1254
01:37:11,209 --> 01:37:18,209
And then, when the last EVA is finished, then
you turn the 14.7 controller back on.

1255
01:37:18,219 --> 01:37:25,219
Now, of course, since you have the proper
oxygen partial pressure, most of the gas that

1256
01:37:27,699 --> 01:37:29,949
comes into the cabin is nitrogen.

1257
01:37:29,949 --> 01:37:34,820
And, actually, I think we may have mentioned
this before, it comes in the bathroom.

1258
01:37:34,820 --> 01:37:41,820
And so, for the time when you are re-pressurizing
the cabin, the bathroom is off limits.

1259
01:37:44,349 --> 01:37:46,030
And I think that is basically it.

1260
01:37:46,030 --> 01:37:51,320
The timing has been pretty good.

1261
01:37:51,320 --> 01:37:51,929
Questions?

1262
01:37:51,929 --> 01:37:52,369
Comments?

1263
01:37:52,369 --> 01:37:53,249
Yeah.

1264
01:37:53,249 --> 01:38:00,249
Is anybody looking at using a fully one atmospheric
spacesuit?

1265
01:38:06,019 --> 01:38:09,159
Actually, it turns out there is a principle
called holdings principle.

1266
01:38:09,159 --> 01:38:16,159
Let me get this up because I have some pictures
of what we were doing.

1267
01:38:32,610 --> 01:38:38,419
If you change by less than a factor of two
you don't get the bends.

1268
01:38:38,419 --> 01:38:40,939
This is an empirical finding.

1269
01:38:40,939 --> 01:38:47,939
And so, the idea was if you could have a suit
that worked at about 8 psi you would have

1270
01:38:48,010 --> 01:38:49,820
a zero pre-breathe suit.

1271
01:38:49,820 --> 01:38:52,079
And I participated in a bunch of tests.

1272
01:38:52,079 --> 01:38:59,079
These are some other robotic things.

1273
01:39:00,929 --> 01:39:06,439
This was the hard suit designed by Ames.

1274
01:39:06,439 --> 01:39:12,539
Because it is a constant volume suit it is
not sensitive to the pressure the way that

1275
01:39:12,539 --> 01:39:16,269
a soft suit is.

1276
01:39:16,269 --> 01:39:19,739
And we did a lot of tests, actually.

1277
01:39:19,739 --> 01:39:23,550
We always came unstuck on the gloves.

1278
01:39:23,550 --> 01:39:30,550
Nobody has been able to design an 8 psi glove
that really gives you sufficient mobility.

1279
01:39:31,869 --> 01:39:32,939
I mean it is a dream.

1280
01:39:32,939 --> 01:39:34,280
People would love to be able to do it.

1281
01:39:34,280 --> 01:39:36,909
If we could figure it out that would solve
all these problems.

1282
01:39:36,909 --> 01:39:43,909
Although, if you are going to Mars maybe you
don't want full pressure because if you have

1283
01:39:47,159 --> 01:39:54,159
one atmosphere compared to 8 or 9 psi your
structure has to be that much thicker and

1284
01:39:55,469 --> 01:39:55,919
heavier.

1285
01:39:55,919 --> 01:39:58,999
They went through some of those calculations.

1286
01:39:58,999 --> 01:40:01,409
This is now on the hand with the Space Station.

1287
01:40:01,409 --> 01:40:05,789
And they figured that for all the meteorite
shielding and everything they had to put on

1288
01:40:05,789 --> 01:40:11,400
the outside of the Space Station that actually
the change in thickness that would be involved

1289
01:40:11,400 --> 01:40:16,978
in changing the pressure from one atmosphere
to another really wouldn't make that much

1290
01:40:16,978 --> 01:40:18,889
of a difference.

1291
01:40:18,889 --> 01:40:22,789
All of these things, again, they are interrelated.

1292
01:40:22,789 --> 01:40:24,749
But it is a good point.

1293
01:40:24,749 --> 01:40:30,209
That is why I showed those designs for 6 psi
because people are still thinking suppose

1294
01:40:30,209 --> 01:40:33,780
we could design a spacesuit to work at a higher
pressure.

1295
01:40:33,780 --> 01:40:40,780
But right now we don't know how to do that.

1296
01:40:43,019 --> 01:40:45,679
I hope everybody has a very happy Thanksgiving.

1297
01:40:45,679 --> 01:40:48,719
We will see you a week from today.

1298
01:40:48,719 --> 01:40:55,719
And if there are any questions, again, about
either your oral presentations or the written

1299
01:40:57,510 --> 01:41:01,329
presentations, I will be here today.

1300
01:41:01,329 --> 01:41:06,070
And then I am gone for the rest of the week,
but I will be looking at emails so you can

1301
01:41:06,070 --> 01:41:08,599
send me emails and we can discuss things.

1302
01:41:08,599 --> 01:41:08,909
OK.