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Today we have an old colleague and friend
of mine.

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Tony Lavoie actually got his engineering degree
in the Aero-Astro Department here at MIT,

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so this is coming back home for him.

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And he actually grew up in Massachusetts.

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But, for the last 23 years, he has been in
Huntsville, Alabama at the Marshall Space

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Flight Center and actually has been an engineer
on quite a few of the projects that I have

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flown with, including the Astro Observatory
and the Tethered Satellite.

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And Tony has continued to rise up in the ranks
of the NASA engineering community.

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He is now, I guess, the Project Manager for
the Robotic Lunar Exploration Program.

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If you have been following the space news,
Marshall Space Flight Center is going to be

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developing the first robotic lunar lander
that we have ever sent to the Moon since Surveyor.

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It will be like 40 years, I guess, we haven't
done that.

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And we are going to have to figure out how
to do it.

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Tony was also the Chief Engineer on the Chandra
X-Ray Observatory which was launched on the

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Shuttle.

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And so, I thought it would be interesting
to hear, since we've been looking at many

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other aspects of Space Shuttle operations,
to hear something about what it was like getting

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a payload ready to fly on the Shuttle.

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But also we were discussing, before class
began, that he may have some comments on the

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Robotic Lunar Exploration Program, which is
now in the pre-phase A studies.

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And it will sort of be interesting.

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We talked a lot about what it was like in
the pre-phase A and the early days of coming

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up with the requirements for the Shuttle.

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And clearly, in the systems engineering, getting
the requirements right is one of the key goals

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for success.

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Tony may have some comments on that.

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I have talked enough.

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Tony, you've got it.

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Hi there.

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We are going to start talking about Chandra.

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And, as Jeff pointed out, I am also going
to talk about my new challenge, my new assignment

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as Project Manager and in pre-phase A what
that means.

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And I think it is a lot different, being a
student, where you have a single closed form

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solution and you go and you work a problem
and it is done.

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In the real world you seldom, if ever, work
a problem one time and have it finish.

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And we will get into that as we go along.

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I am going to talk about Chandra X-Ray Observatory.

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And these are just a few images that Chandra
has produced.

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It is an outstanding x-ray imager, and it
has been flying since July of '99.

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And you are going to get all the gory details
and all the lessons learned that we had in

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working that project.

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I will do an overview Chandra history and
then the challenges we faced and lessons learned

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associated with that, and we will cover those
topics.

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In terms of how we operate, feel free to ask
questions as we go along.

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It is kind of lose and easy.

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Chandra, or back then it was AXAF, Advanced
X-Ray Astrophysics Facility.

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NASA, by the way, loves acronyms.

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I mean, if you are interested in working with
NASA or associated with NASA, they are just

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acronym crazy.

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AXAF was one of the four great observatories.

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The four great observatories were meant to
cover as close to the entire spectrum as NASA

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could.

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And so, the visible great observatory is Hubble.

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And Ultraviolet, that's true, little Ultraviolet.

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The X-Ray Observatory is AXAF, which was later
named Chandra.

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The Gamma Ray Observatory is the Compton Gamma
Ray Observatory.

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And the last one was Infrared.

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And that originally started off as SIRTF.

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And now it is Spitzer.

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And that was launched a few years ago.

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In each of the four great observatories, they
were higher class than most of the other science

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missions, even the science telescopes.

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And NASA did invest quite a bit of money on
each of those.

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And so, you will see that the performance
from the four great observatories are, in

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terms of quality, probably the best in the
world and the best NASA has ever done.

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For the x-ray region, Chandra or AXAF was
built.

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And its objective, you start with program
objectives and you work down with science

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objectives.

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The science objectives were really to understand
the nature of the universe and determine the

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nature of celestial objects, in particular
those that are hot.

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And hot objects will produce x-rays.

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And, of course, Jeff knows all about that.

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If you have any questions related to that
you can ask Jeff.

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But, from an engineer perspective, what happens
is you are given a set of objects and maybe

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a program objective, and now you have to craft
the mission and craft the project from those.

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And one of the problems that you face is that
sometimes they are not crisp and sometimes

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they are flexible based on cost.

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And also sometimes they are not very specific.

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Like determine the nature of celestial objects
from stars to quasars.

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Now what?

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But this is the kind of thing that typically
you start with.

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And you have to iterate with, in this case,
the science community.

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If you are building part of the Shuttle, you
have to iterate with, for instance, the users,

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the astronauts, the payload developers that
would use the Shuttle, the operators, et cetera.

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But the process is the same.

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You start with the top level objectives and
you work your way down.

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Now, again, because of the nature of what
we are talking about, it is usually a very

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iterative process that can last for several
months.

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And even several years if there is a technical
challenge that causes you to stretch out.

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And I will mention when it started.

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In terms of AXAF, kind of the key parameters
are the percent in circled energy, i.e., how

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sharp is the image?

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Registration meaning where is the target in
the sky?

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And you have got to remember that x-ray astronomy
is a relatively new branch of astronomy.

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Because of the atmosphere it absorbs x-rays.

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So we, humans, only discovered x-ray astronomy
in the last 40 years.

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We need to go outside the atmosphere to get
information on x-ray astronomy.

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One of the things that we did know is if there
are some x-ray sources there they may or may

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not be the same sources that also emit invisible
light.

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And, if they are not, then you have a question
of you kind of know there is a source out

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there, but you don't know where in the sky
it is.

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And so, one of the challenges that AXAF had
was even if I have no stars around this x-ray

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source, I have got to be able to pinpoint
where that x-ray source is.

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That was a particular challenge that we had,
trying to figure out how to do that.

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And that is what registration means.

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And then effective area is related to how
many photons you can collect to make a good

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image.

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And recognize that if you are looking at the
sun, the sun is very close so you can get

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a lot of photons, but if you are looking at
something that is ten billion light-years

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away you are not collecting very many photons
so you have to wait a long time to get those

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photons, unless you have a big collecting
area.

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Those are kind of the key performance requirements
that you have to address when you are building

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an x-ray telescope.

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From those there are key derived requirements
that have to be derived basically to be able

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to maximize the scientific performance requirements.

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And so, from these pieces of information,
you derive mirror size and design, you derive

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focal length.

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Pointing and control requirements, how accurately
do you need to point?

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Thermal stability because that plays a role
in orbit, a very big role.

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Instrument sensitivity and the fiducial transfer
system, which I will talk about later, which

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is the thing that allows you to do the registration,
even the absence of local visible stars around

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it.

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Once you have the bulk of the science performance
requirements and the derived requirements

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from these performance requirements then you
fill in kind of the rest of the pie, if you

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will.

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And those can be safety requirements in the
case of a manned program.

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In fact, that is pretty significant.

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And it is a pretty significant cost driver
for things that fly in space.

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Unfortunately, they also cost a lot to make
sure they are not a hazard to the crew that

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flies.

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There are also design and construction standards,
which also turns out to be a big deal.

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For instance, if you are building a satellite
and you have circuit cards, you are going

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to have requirements on soldering, you are
going to have requirements on integrated circuits,

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you are going to have requirements on glazing,
you are going to have requirements on bonding.

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You are going to have requirements on how
to do things across the whole gamut of the

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spacecraft.
Not just the spacecraft but also the Shuttle
and anything that flies up there.

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For a given mission, there are probably on
the order of 100, 150 separate documents that

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describe various things, design and construction
standards that you have to go through for

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a particular piece of building the vehicle.

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And so, those things are always a challenge
for a project manager because the engineers

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want to get the latest standard that applies,
and in excruciating detail as engineers love

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to do.

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And yet, from the project manger's standpoint,
we are trying to maintain cost.

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There is always a tradeoff between how good
is good enough?

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From a program manager's perspective better
is the enemy of good.

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Yet, from an engineer, good is always better,
or better is always better.

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There is always a healthy tension between
the project manager and the engineers.

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And I would say that a successful project
knows how to tradeoff.

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The project manager and the engineers know
how to balance that tension to be able to

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get the best product.

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And we have done that before, and we have
also imbalanced it and had some spectacular

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failures.

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Once requirements are set then you can start
kind of designing and starting to put the

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drawings on developing the system, if you
will.

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But that is kind of the general flow of information
for a science payload or a science mission.

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You start with the top level requirements
for performance, the scientific performance

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that you are looking for.

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From those you derive the direct performance
requirements, like what you see here, and

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then everything else cascades below that.

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And, once you have the requirements set, then
you can start developing concepts.

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Now, this was a preliminary design of AXAF.

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I am not going to talk about it, but I am
just going to show the next slide as to what

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it looks like now.

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And so, you can see that there is a major
difference between what it started out as

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and what it ended up as.

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And this is typical.

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It is not atypical.

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And the reason is cost.

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A lot of times when you are first starting
out with requirements, you kind of don't know

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what the cost of the mission is going to be.

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And so, you come up with an idea that has
a lot of capability.

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This was orbit serviceable, it was in low
earth orbit, and it had four focal plane instruments

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that you could select.

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And it would actually move, much like Hubble.

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And it was a 15 year mission with reservicing
with the shuttle astronauts.

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But, when you start putting that on paper
and you start crafting the requirements, one

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of the things you do, in the early phase of
a program, is you also cost, or you try and

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cost what those requirements result in, in
terms of design.

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Even though you don't do the final design
or you don't start working on the design in

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detail until after you've got the requirements
set, in practical terms you have to still

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put together a concept design so that you
can cost it.

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And that is exactly what happened on AXAF.

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We put together a design in parallel with
working the requirements and we costed the

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design.

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And it turned out that that was more money
than NASA could afford.

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And so, as is typical, the iteration process
begins with headquarters to change the parameters

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of the mission.

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To, in a sense, compromise the scientific
objectives a little bit in terms of implementing

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a requirement set.

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And the result is finally you get something
that you can pay for and that still meets

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the intent of the scientific objectives.

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That is a key lesson to learn.

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When you are first starting out, when you
are first crafting what you want to do, except

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it to change.

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And the key there is it is usually cost driven
as to what you can afford.

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Not only that, NASA, just by the nature of
what it is doing, since it has never built

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an AXAF before, it is really hard to get a
good, accurate cost of what it costs.

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So, a lot of times, the cost is derived from
a parametric usually weight-based system such

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that, for instance, if the mirrors or if the
solar rays, you want them this big to provide

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this much power.

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That big means they have to weigh or they
mass so many kilograms.

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And so that is about X amount of dollars based
on weight.

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Now, there are a lot of additional factors
that you put in like complexity, interfaces,

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et cetera, technology readiness, whether you
are looking for state-of-the-art or something

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that has already flown.

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But generally it is what is called a parametric
cost model.

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And it is not based on taking a look at all
the design drawings and saying this cost this

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much from the vendor, this cost this much,
and you put it all together.

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That is called a bottoms-up assessment.

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And it is more accurate, but it also relies
on having an accurate design picture which

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obviously you don't have early on in a program.

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I mean it is almost like a black art to try
and take a requirement set and craft a design

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early on or at least bound the design and
bound the cost.

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Because, again, early on what you are trying
to do is get into the cost envelope and still

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meet the scientific objectives or the objectives
that you are trying to do.

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Yes.

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In this final design, how are its capabilities
versus the original?

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I mean because you didn't put as much money
into it.

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Correct.

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To make it on-orbit replaceable means that
all of the boxes that you see in the spacecraft

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00:18:46,830 --> 00:18:53,830
bus, or a lot of them would have had to have
been, on this picture, replaceable.

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00:18:54,050 --> 00:18:55,500
They were all replaceable.

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00:18:55,500 --> 00:18:59,740
You have to spend some money making sure that
the drawers slide in, slide out, there are

224
00:18:59,740 --> 00:19:02,490
no sharp edges and it is accessible, et cetera.

225
00:19:02,490 --> 00:19:05,030
So, packaging is important.

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00:19:05,030 --> 00:19:09,930
That is one area where you can reduce cost
and not really have an effect on performance,

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00:19:09,930 --> 00:19:11,890
per se.

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00:19:11,890 --> 00:19:15,720
However, one of the big areas that we did
take a little bit of a hit on performances

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00:19:15,720 --> 00:19:17,420
is on the mirrors.

230
00:19:17,420 --> 00:19:23,450
Now, x-rays, you cannot just have a regular
shaped lens.

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00:19:23,450 --> 00:19:25,880
What we use is grazing incidence mirrors.

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And I will explain this later.

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00:19:27,120 --> 00:19:32,470
Because the x-rays are so highly energetic,
you have to graze them gradually to a focus.

234
00:19:32,470 --> 00:19:36,190
And the original concept had six mirrors nested.

235
00:19:36,190 --> 00:19:41,300
They were basically hyperbola parabola shaped.

236
00:19:41,300 --> 00:19:43,360
The final concept had four.

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00:19:43,360 --> 00:19:50,360
We had to remove, not the inside or the outside,
but two of the middle mirrors.

238
00:19:50,560 --> 00:19:54,000
So, the mirror set is four.

239
00:19:54,000 --> 00:19:58,400
This orbit that this flies in is a highly
elliptical orbit.

240
00:19:58,400 --> 00:20:03,470
It is about 140,000 kilometers by 10,000 kilometers.

241
00:20:03,470 --> 00:20:10,220
The original orbit was in low earth orbit
which is about 350 kilometers.

242
00:20:10,220 --> 00:20:15,060
And so that affects the viewing time.

243
00:20:15,060 --> 00:20:22,050
But, in all of the other registration and
encircled energy, I think that we still were

244
00:20:22,050 --> 00:20:26,980
able to meet the original objectives of the
scientific mission.

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00:20:26,980 --> 00:20:33,370
There are ways to compromise that don't really
affect directly what the scientists want to

246
00:20:33,370 --> 00:20:34,490
do, but it is a tradeoff.

247
00:20:34,490 --> 00:20:40,240
It is usually not their first desire but they
signed up to it, they are comfortable with

248
00:20:40,240 --> 00:20:45,610
the final answer.

249
00:20:45,610 --> 00:20:49,030
Explaining a little bit of how it is put together.

250
00:20:49,030 --> 00:20:52,380
This is a rather simplified version.

251
00:20:52,380 --> 00:20:53,210
Here are the solar rays.

252
00:20:53,210 --> 00:20:54,630
That is where we get our power.

253
00:20:54,630 --> 00:20:57,250
This is the spacecraft bus.

254
00:20:57,250 --> 00:21:01,690
This is the HRMA which is the mirrors, the
nested cylinders that I was talking about

255
00:21:01,690 --> 00:21:03,290
earlier.

256
00:21:03,290 --> 00:21:07,540
This is a low energy grading and a high energy
grading.

257
00:21:07,540 --> 00:21:13,410
For spectroscopy, what you want to do is you
want to bend all of the photons in a particular

258
00:21:13,410 --> 00:21:17,250
energy much like a prism does for visible
light.

259
00:21:17,250 --> 00:21:19,820
And the way you do that is with these facets.

260
00:21:19,820 --> 00:21:24,220
There are probably a thousand facets on this.

261
00:21:24,220 --> 00:21:25,530
And I have a picture of that later.

262
00:21:25,530 --> 00:21:30,540
And you flip it into the beam when you want
to get some spectroscopy data.

263
00:21:30,540 --> 00:21:37,540
And you remove the grading when you want to
get an x-ray image of what you are looking

264
00:21:37,850 --> 00:21:38,600
at.

265
00:21:38,600 --> 00:21:43,600
And that is a function of what the scientists
want to do at a particular target.

266
00:21:43,600 --> 00:21:48,970
Some scientists want to get an image because
that conveys more information for them than

267
00:21:48,970 --> 00:21:50,760
spectroscopy.

268
00:21:50,760 --> 00:21:56,890
Others want to see a spectrogram of the image
because that tells them what the photons are

269
00:21:56,890 --> 00:21:58,980
and what the energy of the photons are.

270
00:21:58,980 --> 00:22:05,370
And that can tell you, for instance, what
elements are present and what temperatures

271
00:22:05,370 --> 00:22:10,610
for a given gas cloud or neutron star or what
have you.

272
00:22:10,610 --> 00:22:12,200
And then we have an optical bench.

273
00:22:12,200 --> 00:22:15,400
And all that means is it is a piece of structure
that is very stiff.

274
00:22:15,400 --> 00:22:22,020
Because obviously you can tell if you flex
a lot that sure doesn't help your camera imaging

275
00:22:22,020 --> 00:22:22,720
the performance.

276
00:22:22,720 --> 00:22:27,910
It has got to be very stiff, and that is why
they call it an optical bench.

277
00:22:27,910 --> 00:22:31,660
And the ISM is the Integrated Science Module.

278
00:22:31,660 --> 00:22:38,310
That is where the instruments sit in Chandra.

279
00:22:38,310 --> 00:22:44,770
And here is a picture, as I mentioned before,
of how the x-rays graze off of the cylinders

280
00:22:44,770 --> 00:22:48,450
in the HRMA down to a focal point about ten
meters away.

281
00:22:48,450 --> 00:22:55,450
Jeff had mentioned that sometimes it takes
quite a while for science to come to fruition

282
00:22:59,440 --> 00:23:00,800
in a mission.

283
00:23:00,800 --> 00:23:02,820
And this is probably a good case.

284
00:23:02,820 --> 00:23:07,340
It started in 1978 with some concepts.

285
00:23:07,340 --> 00:23:14,340
We did get approval for new start in 1988,
so you can tell there was ten years time where

286
00:23:15,120 --> 00:23:19,120
this was just an idea in a scientist's mind.

287
00:23:19,120 --> 00:23:26,120
And typically the course of events is that
the scientist lobbies and submits papers,

288
00:23:27,660 --> 00:23:34,070
submits proposals to NASA, lobbies Congress,
lobbies the National Science Foundation to

289
00:23:34,070 --> 00:23:38,260
say this is a good idea, we should do this
and here is the concept.

290
00:23:38,260 --> 00:23:45,260
And, of course, that concept changes over
time as you get new technology, et cetera.

291
00:23:45,990 --> 00:23:48,350
And so, that is exactly what happened here.

292
00:23:48,350 --> 00:23:53,650
We did get approval ten years from when the
original concept started.

293
00:23:53,650 --> 00:24:00,650
Authority to proceed for the prime contract
was in January 1989.

294
00:24:00,820 --> 00:24:07,400
What this means is that is when we hired a
contractor to build the spacecraft.

295
00:24:07,400 --> 00:24:11,570
And the start of that process is called ATP.

296
00:24:11,570 --> 00:24:13,770
We had two separate ATPs.

297
00:24:13,770 --> 00:24:20,400
Sometimes you can say I can let out one contract
to a company and let that company buy the

298
00:24:20,400 --> 00:24:25,010
science instruments or I can compete the science
instruments separately.

299
00:24:25,010 --> 00:24:32,010
And there are various pros and cons, but in
this case NASA decided to compete the instruments

300
00:24:32,630 --> 00:24:34,430
separately.

301
00:24:34,430 --> 00:24:41,160
From an engineer's point of view, one of the
things that should peak your interest or note

302
00:24:41,160 --> 00:24:46,730
that when you have separate contracts you
always have a question of integration.

303
00:24:46,730 --> 00:24:48,990
If you are going to compete separately, you
are going to have two separate pieces.

304
00:24:48,990 --> 00:24:51,590
Who is going to integrate them?

305
00:24:51,590 --> 00:24:55,720
The integration job will be harder when you
compete them separately.

306
00:24:55,720 --> 00:25:01,560
Now, your performance is probably better when
you have direct insight into the instruments

307
00:25:01,560 --> 00:25:04,790
and direct insight into the spacecraft contractor.

308
00:25:04,790 --> 00:25:09,620
But the penalty is now, when you integrate
the two, you have to make sure that works.

309
00:25:09,620 --> 00:25:14,600
And so, as a project manager, as a systems
engineer you have to make sure you apply enough

310
00:25:14,600 --> 00:25:19,930
resources to make sure they work together
and continue to work together as they are

311
00:25:19,930 --> 00:25:26,930
defining the interfaces, for instance, between
the two elements.

312
00:25:28,680 --> 00:25:35,680
This was interesting in that in order to get
it funded, Congress said we will let you build

313
00:25:36,290 --> 00:25:42,590
an AXAF but, along the way, you have to do
some testing to show that you can meet the

314
00:25:42,590 --> 00:25:45,450
performance that you say you can meet.

315
00:25:45,450 --> 00:25:52,450
And so, we were required by law to have a
test of the mirrors in June of '91.

316
00:25:53,240 --> 00:26:00,240
And we also had another test later on, the
same thing, to verify that we could get the

317
00:26:00,310 --> 00:26:07,310
performance that we showed on paper with actual
hardware before we committed to fly and before

318
00:26:09,390 --> 00:26:13,600
NASA committed to spend the rest of the money
to fly.

319
00:26:13,600 --> 00:26:19,220
And so, sometimes that happens, sometimes
if you have a smaller program it doesn't go

320
00:26:19,220 --> 00:26:22,660
to Congress so you don't get into those things.

321
00:26:22,660 --> 00:26:27,490
But, when you have a great observatory and
NASA is spending a lot of money, a lot of

322
00:26:27,490 --> 00:26:34,360
times Congress will get in and say yes, you're
constrained, but you have to show me along

323
00:26:34,360 --> 00:26:38,420
the way that you can do this.

324
00:26:38,420 --> 00:26:45,420
I wouldn't be surprised if Congress does that
for the CEV, the new vehicle coming up, or

325
00:26:45,710 --> 00:26:47,250
the CLV.

326
00:26:47,250 --> 00:26:53,300
In fact, for the CLV, the launch vehicle,
there is a push to have a demonstration test

327
00:26:53,300 --> 00:26:58,710
early just to verify that we can do it.

328
00:26:58,710 --> 00:27:03,830
Now, during this time, of course, we are still
formulating requirements.

329
00:27:03,830 --> 00:27:05,730
And we rack up the cost.

330
00:27:05,730 --> 00:27:09,730
And, low and behold, NASA cannot afford it.

331
00:27:09,730 --> 00:27:14,750
We went through a program restructure at that
time where we dropped a couple of the mirrors,

332
00:27:14,750 --> 00:27:19,780
we changed its orbit, we removed crew servicing.

333
00:27:19,780 --> 00:27:24,240
And you could tell that the whole shape of
the spacecraft changed.

334
00:27:24,240 --> 00:27:27,860
Again, that is unfortunately not atypical.

335
00:27:27,860 --> 00:27:28,980
It happens quite often.

336
00:27:28,980 --> 00:27:29,930
Yes.

337
00:27:29,930 --> 00:27:36,930
What was the reason for the orbit change?

338
00:27:39,120 --> 00:27:41,780
Good question.

339
00:27:41,780 --> 00:27:44,570
In orbit there are Van Allen Radiation Belts.

340
00:27:44,570 --> 00:27:51,360
And we really cannot observe too well within
those belts.

341
00:27:51,360 --> 00:27:55,730
Now, in the first mission, the low earth orbit
mission we were below the belts so we could

342
00:27:55,730 --> 00:27:56,220
operate.

343
00:27:56,220 --> 00:28:03,000
But the problem with low earth orbit is you
have this big earth, you are close to earth,

344
00:28:03,000 --> 00:28:06,130
and so you need power from the sun.

345
00:28:06,130 --> 00:28:09,130
And, guess what, the sun goes behind the earth.

346
00:28:09,130 --> 00:28:14,570
And so, you are eclipsed for a good percentage
of the orbit time.

347
00:28:14,570 --> 00:28:21,570
When we had a 15 year mission in low earth
orbit we said since we don't have servicing,

348
00:28:21,930 --> 00:28:23,700
the lifetime cuts down to five years.

349
00:28:23,700 --> 00:28:28,309
Now, if I am five years in low earth orbit,
I have just lost two-thirds of my mission

350
00:28:28,309 --> 00:28:29,340
time.

351
00:28:29,340 --> 00:28:34,330
So let's see if we can crank up the orbit,
get as far outside the radiation belts as

352
00:28:34,330 --> 00:28:34,870
we can.

353
00:28:34,870 --> 00:28:40,550
And then we have basically 100% visibility,
the whole orbit, if we can get completely

354
00:28:40,550 --> 00:28:41,170
outside.

355
00:28:41,170 --> 00:28:48,170
The problem with that is that costs propellant
because the radiation belts end, they breathe,

356
00:28:49,630 --> 00:28:53,240
but roughly around 60,000 kilometers.

357
00:28:53,240 --> 00:28:59,990
We could raise apogee to 140,000, but we didn't
have enough money to raise perigee.

358
00:28:59,990 --> 00:29:02,580
It gets down to money again.

359
00:29:02,580 --> 00:29:05,580
So, perigee stayed at about 10,000 kilometers.

360
00:29:05,580 --> 00:29:10,760
The resulting orbit time, if you looked at
the integral of time outside the radiation

361
00:29:10,760 --> 00:29:13,350
belts, was probably about 70%.

362
00:29:13,350 --> 00:29:16,180
It was a compromise.

363
00:29:16,180 --> 00:29:23,180
We did end up losing some overall time, but
about 70% of the orbit is usable for viewing.

364
00:29:26,590 --> 00:29:32,830
That is the strategy and that is why we went
to a different orbit.

365
00:29:32,830 --> 00:29:36,650
As you can tell, there are a lot of things
that are traded off during that time to fit

366
00:29:36,650 --> 00:29:39,000
within the constraints that you have got.

367
00:29:39,000 --> 00:29:44,190
Again, that is typical.

368
00:29:44,190 --> 00:29:48,350
The three reviews that are kind of standard
reviews for all programs and projects are

369
00:29:48,350 --> 00:29:49,950
you start with a requirements review.

370
00:29:49,950 --> 00:29:52,070
And that is pretty basic.

371
00:29:52,070 --> 00:29:57,360
It is held early on.

372
00:29:57,360 --> 00:30:01,320
Requirements have started before that review.

373
00:30:01,320 --> 00:30:04,070
For science missions, you start with science
objectives.

374
00:30:04,070 --> 00:30:06,450
And you are percolating science requirements.

375
00:30:06,450 --> 00:30:13,140
And the system requirements review is really
a review that baselines, if you will, and

376
00:30:13,140 --> 00:30:18,480
sets the requirements as firm as you can.

377
00:30:18,480 --> 00:30:25,480
And it is usually after you have gone through
the cost gyrations, but it is done prior to

378
00:30:27,700 --> 00:30:29,460
doing any of the design reviews.

379
00:30:29,460 --> 00:30:34,550
Once you have a requirements review done,
it was in December of '92, almost two years

380
00:30:34,550 --> 00:30:40,059
later we had what is called a preliminary
design review in November of '94.

381
00:30:40,059 --> 00:30:46,630
The third review is called a critical design
review in February of '96.

382
00:30:46,630 --> 00:30:51,760
What makes a preliminary design review and
critical design review has to do with the

383
00:30:51,760 --> 00:30:53,740
maturity level of the design.

384
00:30:53,740 --> 00:31:00,430
For critical design review, supposedly you
have on the order of 90% of your drawings

385
00:31:00,430 --> 00:31:05,280
complete and on the order of 10% of your hardware
built.

386
00:31:05,280 --> 00:31:12,280
And I think for PDR it is about 10% of your
drawings built, the final drawings.

387
00:31:14,900 --> 00:31:18,850
That kind of gages what you are talking about
there.

388
00:31:18,850 --> 00:31:23,760
And it is a typical milestone that NASA uses
for all of its programs.

389
00:31:23,760 --> 00:31:30,760
Usually these are set early on in the mission,
in the program milestones.

390
00:31:31,240 --> 00:31:37,550
And, for political and for programmatic reasons,
you tend not to deviate.

391
00:31:37,550 --> 00:31:39,210
You try and meet those milestones.

392
00:31:39,210 --> 00:31:45,190
Even if the project is not as mature as you
would like, usually that is one that you try

393
00:31:45,190 --> 00:31:46,309
and keep hold of.

394
00:31:46,309 --> 00:31:52,840
Maybe you don't have 10%, maybe you have 5%
or maybe you don't have 90% you have 70%.

395
00:31:52,840 --> 00:31:58,320
Sometimes you do go and you hold the milestone,
you hold the review, but when you are not

396
00:31:58,320 --> 00:32:04,520
mature enough sometimes you have to hold a
delta review to catch up.

397
00:32:04,520 --> 00:32:10,100
And that is, again, something that NASA does
for various reasons.

398
00:32:10,100 --> 00:32:16,610
If the situation is right, sometimes you can
slip and allow a single review at the right

399
00:32:16,610 --> 00:32:17,540
time.

400
00:32:17,540 --> 00:32:24,540
Most often it is driven by nontechnical things
that require you, either by your customer

401
00:32:27,730 --> 00:32:33,830
headquarters, they don't want you to slip
so you tend to hold it where he said he wanted

402
00:32:33,830 --> 00:32:36,880
it.

403
00:32:36,880 --> 00:32:41,929
And then we had the mirror delivery to the
calibration facility in November.

404
00:32:41,929 --> 00:32:48,809
It shipped the whole thing to the Cape for
launch in February and we launched in July.

405
00:32:48,809 --> 00:32:55,059
You can see we spent about five or six months
down at the Cape integrating into the Shuttle

406
00:32:55,059 --> 00:33:00,809
testing, and then we flew in July of '99.

407
00:33:00,809 --> 00:33:02,660
Those are the orbit parameters.

408
00:33:02,660 --> 00:33:06,380
We achieved the final orbit August 7th, so
you can see about two weeks.

409
00:33:06,380 --> 00:33:12,450
And the way we did that is the Shuttle only
puts stuff to low earth orbit, so you need

410
00:33:12,450 --> 00:33:14,550
some additional propulsion.

411
00:33:14,550 --> 00:33:21,040
We had an upper-stage that got us part of
the way there, used most of the energy.

412
00:33:21,040 --> 00:33:22,880
However, it wasn't at the final orbit.

413
00:33:22,880 --> 00:33:29,880
So, integral to the spacecraft, we had a propulsion
system that had to do five additional burns

414
00:33:30,960 --> 00:33:35,890
to get us to the final altitude and the final
orbit parameters.

415
00:33:35,890 --> 00:33:38,700
That is why it took us about two weeks.

416
00:33:38,700 --> 00:33:41,640
And, again, that is not atypical.

417
00:33:41,640 --> 00:33:46,640
When you are not operating in low earth orbit,
it takes you while to get your final orbit.

418
00:33:46,640 --> 00:33:51,770
And these are a couple of interesting parameters.

419
00:33:51,770 --> 00:33:53,990
Safe mode, we will talk a little bit about
that.

420
00:33:53,990 --> 00:33:59,670
Spacecraft are designed such that if -- Yeah.

421
00:33:59,670 --> 00:34:06,670
I am just wondering if the inclination affects
the requirements at all or does it not really

422
00:34:12,339 --> 00:34:12,589
matter so it just stays [NOISE OBSCURES]?

423
00:34:12,550 --> 00:34:17,719
The 28.5 is driven largely by the launch site
at Kennedy Space Center.

424
00:34:17,719 --> 00:34:18,279
Right.

425
00:34:18,279 --> 00:34:25,279
I am just wondering if the science requirements
could drive the inclination [OVERLAPPING VOICES].

426
00:34:26,149 --> 00:34:27,918
For some missions, yes.

427
00:34:27,918 --> 00:34:34,440
We were fairly incentive to that, as long
as we took advantage of launching at KSC at

428
00:34:34,440 --> 00:34:35,889
the optimum inclination.

429
00:34:35,889 --> 00:34:38,369
But there are missions like Space Station.

430
00:34:38,369 --> 00:34:45,369
Because you have a launch from KSC and a launch
from Russia, to optimize the performance of

431
00:34:47,989 --> 00:34:52,889
both launch centers then the orbit is 58.5.

432
00:34:52,889 --> 00:34:56,748
Now, what that means to KSC launch is that
you pay a significant penalty.

433
00:34:56,748 --> 00:35:03,749
You pay about a 30% weight penalty for launch
at KSC to the Space Station.

434
00:35:05,799 --> 00:35:12,799
Sometimes the answer is yes, you can optimize
inclination, and sometimes, when you have

435
00:35:13,140 --> 00:35:17,839
a large program and multiple launch sites
it is a compromise.

436
00:35:17,839 --> 00:35:21,380
So, it is not efficient for each site.

437
00:35:21,380 --> 00:35:28,380
I was mentioning spacecraft typically have
their avionics systems.

438
00:35:30,329 --> 00:35:34,039
And typically they do not contract the ground.

439
00:35:34,039 --> 00:35:37,519
They are not in communication with the ground
all the time.

440
00:35:37,519 --> 00:35:39,210
And so, for Chandra, that is the case.

441
00:35:39,210 --> 00:35:46,210
We may have "contact" with Chandra probably
about 5% to 10% of the time per day.

442
00:35:47,640 --> 00:35:54,640
In the meantime, figure that 90% of the time
it is out of communication range.

443
00:35:56,210 --> 00:36:00,220
Now, this is something, by the way, that is
somewhat different from a manned mission.

444
00:36:00,220 --> 00:36:05,960
The manned missions tend to optimize and maximize
communication coverage.

445
00:36:05,960 --> 00:36:12,960
When Jeff is flying in the Shuttle we probably
have 90%, 95% coverage over an orbit and over

446
00:36:13,180 --> 00:36:16,019
a day for communication.

447
00:36:16,019 --> 00:36:19,119
But, in science missions, rarely is that the
case.

448
00:36:19,119 --> 00:36:25,900
And so what that means is the whole philosophy
of operating a science mission is based on

449
00:36:25,900 --> 00:36:28,069
stored commands.

450
00:36:28,069 --> 00:36:30,460
And so, we send up a stored command load.

451
00:36:30,460 --> 00:36:31,960
And that load is good for a day.

452
00:36:31,960 --> 00:36:37,390
And basically it steps through and automatically
executes based on time.

453
00:36:37,390 --> 00:36:43,980
What that also means is you have to design
a spacecraft to recognize when it has a problem.

454
00:36:43,980 --> 00:36:50,799
If a hardware box has a failure, it has got
to be able to recognize that and go into a

455
00:36:50,799 --> 00:36:57,799
safe mode so that the ground can then recover
and configure the systems to continue to operate.

456
00:36:58,509 --> 00:37:05,509
That is one part of flying a spacecraft, is
building a robust safe mode to be able to

457
00:37:06,309 --> 00:37:07,289
do that.

458
00:37:07,289 --> 00:37:12,769
And our first problem occurred August 17,
1999.

459
00:37:12,769 --> 00:37:14,710
Now, note it was a ground error.

460
00:37:14,710 --> 00:37:21,710
As usually the case, spacecraft are pretty
complicated.

461
00:37:22,460 --> 00:37:29,460
And we probably had 400 or 500 separate procedures
and commands on the ground for doing certain

462
00:37:31,700 --> 00:37:33,170
things.

463
00:37:33,170 --> 00:37:40,170
And, even though we try and test them out
individually, the combination of those procedures

464
00:37:40,180 --> 00:37:45,809
and in the execution, sometimes you put the
spacecraft in the wrong configuration with

465
00:37:45,809 --> 00:37:50,680
one sequence, and then you follow with another
sequence.

466
00:37:50,680 --> 00:37:57,230
Low and behold, the software that you designed
for safe mode says I am in the wrong configuration.

467
00:37:57,230 --> 00:37:59,960
Sorry, I am going to safe mode.

468
00:37:59,960 --> 00:38:02,759
And so, that happens.

469
00:38:02,759 --> 00:38:08,210
We have had only probably three safe mode
events for six years, so that is not too bad

470
00:38:08,210 --> 00:38:09,109
at all.

471
00:38:09,109 --> 00:38:13,660
Hubble, for instance, has had probably an
order of magnitude more than that.

472
00:38:13,660 --> 00:38:20,319
I think we have gotten smarter based on our
design of Hubble to design this.

473
00:38:20,319 --> 00:38:27,319
But, again, typically spacecraft do have safe
mode designs in them.

474
00:38:29,470 --> 00:38:33,039
Given our orbit, we still have a small eclipse
season.

475
00:38:33,039 --> 00:38:38,690
Twice a year in the fall and in the spring
we have eclipses.

476
00:38:38,690 --> 00:38:45,690
And so our first eclipse season was then.

477
00:38:47,450 --> 00:38:51,910
This is the translation mechanics for the
science instruments.

478
00:38:51,910 --> 00:38:53,980
This is where the telescope is.

479
00:38:53,980 --> 00:38:54,999
I won't go through that.

480
00:38:54,999 --> 00:39:01,999
This is kind of where we purchases or we contracted
for the various instruments.

481
00:39:03,819 --> 00:39:09,259
This is a CCD imaging spectrometer.

482
00:39:09,259 --> 00:39:16,259
In fact, it was both Penn State and MIT that
produced this one.

483
00:39:16,259 --> 00:39:22,029
And that is one of the focal plate instruments
and the other one was a high resolution camera

484
00:39:22,029 --> 00:39:26,170
using micro-channel plate technology instead
of a CCD.

485
00:39:26,170 --> 00:39:30,369
And that one was from SAO just down the street
in Cambridge.

486
00:39:30,369 --> 00:39:35,710
The high energy transmission grating, as I
had mentioned, was also from MIT.

487
00:39:35,710 --> 00:39:40,440
And the low energy grating was from the Netherlands.

488
00:39:40,440 --> 00:39:45,450
And this is a good point to make also, is
that a lot of times for science instruments

489
00:39:45,450 --> 00:39:51,210
or for science missions, NASA tries to lower
the cost of the mission.

490
00:39:51,210 --> 00:39:57,809
And the way you can do that is you can reduce
requirements or you can get a partner and

491
00:39:57,809 --> 00:40:03,319
have the partner pay for an instrument that
you want to fly.

492
00:40:03,319 --> 00:40:09,589
And so, in this case, as is typically the
case for science missions, NASA tries to go

493
00:40:09,589 --> 00:40:15,979
and get international partners that will bring
to the table an element or a piece of hardware

494
00:40:15,979 --> 00:40:21,910
or some software that reduces the overall
cost of the mission but, at the same time,

495
00:40:21,910 --> 00:40:24,349
maintains its capability.

496
00:40:24,349 --> 00:40:29,549
That is what we did with the low energy transmission
grating.

497
00:40:29,549 --> 00:40:35,140
We got the Netherlands to basically design
and build that and fly that in exchange for

498
00:40:35,140 --> 00:40:38,400
that kind of arrangement.

499
00:40:38,400 --> 00:40:45,400
They get a percentage of viewing time that
they can say for 5% of the viewing time we

500
00:40:45,700 --> 00:40:49,049
get to point the telescope to wherever we
want.

501
00:40:49,049 --> 00:40:56,049
And so, typically that is kind of the handoff
between our international partners and NASA

502
00:40:56,930 --> 00:41:02,619
in trying to reduce the overall cost to NASA
for a given mission.

503
00:41:02,619 --> 00:41:07,180
And these are the gratings, as I had mentioned.

504
00:41:07,180 --> 00:41:10,390
And there are a bunch of facets along these.

505
00:41:10,390 --> 00:41:16,180
Now, notice these are the four mirror shells
where they co-align with the four mirror shells,

506
00:41:16,180 --> 00:41:22,119
the inner most and the outer most.

507
00:41:22,119 --> 00:41:23,849
And this is kind of how it works.

508
00:41:23,849 --> 00:41:26,660
The gratings get flipped in.

509
00:41:26,660 --> 00:41:29,900
And this is the array of CCDs.

510
00:41:29,900 --> 00:41:32,470
Each one of these is a CCD.

511
00:41:32,470 --> 00:41:39,470
And the pattern of light or the pattern of
x-rays follows along these lines when the

512
00:41:39,890 --> 00:41:41,690
x-rays actually come in.

513
00:41:41,690 --> 00:41:46,390
That is what actually you see.

514
00:41:46,390 --> 00:41:48,809
Now, Chandra does have a ground system architecture.

515
00:41:48,809 --> 00:41:52,069
We communicate with the deep space network.

516
00:41:52,069 --> 00:41:59,069
That is how we communicate because it is not
in low earth orbit so we cannot use the satellites

517
00:42:00,249 --> 00:42:03,489
that are around the earth.

518
00:42:03,489 --> 00:42:08,839
We get that signal from that satellite and
it is beamed to the control center, here in

519
00:42:08,839 --> 00:42:10,579
Cambridge, in fact.

520
00:42:10,579 --> 00:42:13,089
And we do various things on the data.

521
00:42:13,089 --> 00:42:16,599
We process it out and send it to the general
observers.

522
00:42:16,599 --> 00:42:23,599
Now, the way this operates is that every year
this control center or the science folks operating

523
00:42:25,660 --> 00:42:29,809
the control center solicit objectives.

524
00:42:29,809 --> 00:42:36,670
OK, science community come and request time
and give me a proposal for viewing time for

525
00:42:36,670 --> 00:42:40,299
what you want to do, what target you want
to look at, what is the configuration of the

526
00:42:40,299 --> 00:42:42,559
instrument, which instrument, et cetera.

527
00:42:42,559 --> 00:42:47,759
And so, the Chandra folks go through, and
they probably collect about 800 proposals

528
00:42:47,759 --> 00:42:51,829
a year from all around the world.

529
00:42:51,829 --> 00:42:55,960
They will select roughly about 200.

530
00:42:55,960 --> 00:42:59,099
And it is not based on numbers, it is based
on time.

531
00:42:59,099 --> 00:43:04,960
You have a certain amount of seconds in a
year that is available.

532
00:43:04,960 --> 00:43:09,319
And so, some of these proposals have large
times, some have small times, but roughly

533
00:43:09,319 --> 00:43:11,190
it is about a four to one.

534
00:43:11,190 --> 00:43:16,700
About 200 are selected, 800 are proposed,
so that's good, you're oversubscribed, you

535
00:43:16,700 --> 00:43:18,650
have a lot of interest.

536
00:43:18,650 --> 00:43:21,259
NASA does fund those that are selected.

537
00:43:21,259 --> 00:43:26,430
So if you are a PI and you say I want to go
look at Crab Nebula or I want to go look at

538
00:43:26,430 --> 00:43:32,589
a Quasar somewhere, and here are the reasons,
here is what that will tell me.

539
00:43:32,589 --> 00:43:33,579
And it gets selected.

540
00:43:33,579 --> 00:43:39,059
NASA will fund you some money to be able to
do that observation and process the data and

541
00:43:39,059 --> 00:43:40,390
publish.

542
00:43:40,390 --> 00:43:44,839
Now, NASA won't fund any that were selected
from foreign countries.

543
00:43:44,839 --> 00:43:51,839
So the foreign countries, they have to get
their funding, but we will allow them viewing

544
00:43:52,279 --> 00:43:53,249
time.

545
00:43:53,249 --> 00:43:54,960
And that is also typically the case.

546
00:43:54,960 --> 00:44:01,960
And, by the way, all of these scientists across
the world never have to come to Cambridge.

547
00:44:04,789 --> 00:44:07,859
It is all done electronically.

548
00:44:07,859 --> 00:44:09,460
They don't get their data real-time.

549
00:44:09,460 --> 00:44:13,729
They get it probably a few weeks after the
observation.

550
00:44:13,729 --> 00:44:16,269
And the reason for that is there is a lot
of processing.

551
00:44:16,269 --> 00:44:21,680
You don't actually send, or you can, but usually
you don't send the raw data out to the user.

552
00:44:21,680 --> 00:44:27,650
It is heavily processed, and the products
of that processing are what is actually sent

553
00:44:27,650 --> 00:44:28,779
out.

554
00:44:28,779 --> 00:44:34,390
Now, there are tools that the Control Center
also provides, but generally it is the process

555
00:44:34,390 --> 00:44:37,950
data that is sent.

556
00:44:37,950 --> 00:44:38,390
Yes?

557
00:44:38,390 --> 00:44:45,390
What sort of data is this?

558
00:44:46,690 --> 00:44:46,940
Images or numerical data?

559
00:44:46,910 --> 00:44:50,950
It is data that can be used for images.

560
00:44:50,950 --> 00:44:57,950
It can be used for registering each photon,
what energy it is.

561
00:44:58,049 --> 00:45:01,359
There are a lot of different choices of data.

562
00:45:01,359 --> 00:45:08,359
And some of the data is overlapping, but it
does give you information on energy, location,

563
00:45:09,859 --> 00:45:16,859
number count, where in the field.

564
00:45:18,960 --> 00:45:25,710
It can be used to then process an image or
process a spectrogram.

565
00:45:25,710 --> 00:45:28,859
And you do that by using the tools that are
also provided.

566
00:45:28,859 --> 00:45:35,329
It is like a viewer or it is like a piece
of software that allows you to view what is

567
00:45:35,329 --> 00:45:36,109
in that data.

568
00:45:36,109 --> 00:45:37,529
But the data is just the raw data.

569
00:45:37,529 --> 00:45:43,009
It is just a series of tables.

570
00:45:43,009 --> 00:45:45,819
And, as we said, it began in 1978.

571
00:45:45,819 --> 00:45:48,579
I picked the prime and was given a new start.

572
00:45:48,579 --> 00:45:51,829
I am not going to go through these.

573
00:45:51,829 --> 00:45:54,229
It was restructured.

574
00:45:54,229 --> 00:45:55,729
We went to four mirror pairs.

575
00:45:55,729 --> 00:45:59,819
We dropped two focal plane instruments, dropped
the servicing requirements.

576
00:45:59,819 --> 00:46:00,519
I mentioned that.

577
00:46:00,519 --> 00:46:07,519
Interestingly enough, one of the instruments
we wanted to create a separate spacecraft

578
00:46:09,619 --> 00:46:12,160
just for that instrument.

579
00:46:12,160 --> 00:46:19,029
And, believe it or not, the addition of this
spacecraft and this one for the spectroscopy

580
00:46:19,029 --> 00:46:21,759
mission was going to be cheaper than the original
concept.

581
00:46:21,759 --> 00:46:28,759
But again, due to cost, we continued this
spectroscopy spacecraft for about a year to

582
00:46:31,609 --> 00:46:32,430
two years.

583
00:46:32,430 --> 00:46:36,269
And then that was cut due to cost.

584
00:46:36,269 --> 00:46:40,170
So we ended up flying just this one spacecraft.

585
00:46:40,170 --> 00:46:47,170
And the result is the Chandra Observatory
that we have now.

586
00:46:47,619 --> 00:46:51,839
Note that sometimes it is not within your
control as to whether your program is cancelled

587
00:46:51,839 --> 00:46:52,749
or not.

588
00:46:52,749 --> 00:46:55,470
We were doing quite well.

589
00:46:55,470 --> 00:46:59,559
It was within our cost envelope that they
had given us.

590
00:46:59,559 --> 00:47:04,880
But, at the time, there were other priorities
at NASA and there were other overruns at NASA.

591
00:47:04,880 --> 00:47:06,989
And they have to weigh.

592
00:47:06,989 --> 00:47:11,410
Sometimes they say, well, you can have this
much money for these many years.

593
00:47:11,410 --> 00:47:13,970
And every year they re-evaluate.

594
00:47:13,970 --> 00:47:19,710
And that is because you don't know how much
things are going to cost because NASA typically

595
00:47:19,710 --> 00:47:26,269
builds one of a kind things, and you don't
know really how much it costs until it is

596
00:47:26,269 --> 00:47:27,609
already done.

597
00:47:27,609 --> 00:47:31,079
So that re-evaluation process continues now.

598
00:47:31,079 --> 00:47:34,339
And it will probably continue for as long
as NASA flies.

599
00:47:34,339 --> 00:47:40,549
So imaging and spectroscopy is what we do.

600
00:47:40,549 --> 00:47:42,190
Why is imaging so important?

601
00:47:42,190 --> 00:47:49,190
Well, clearly this image was a Rosat image
with the highest technology at the time.

602
00:47:50,249 --> 00:47:52,680
And here is the Chandra image.

603
00:47:52,680 --> 00:47:55,719
And you can see the neutron star right there.

604
00:47:55,719 --> 00:48:00,390
And there is no way you can see a neutron
star in there.

605
00:48:00,390 --> 00:48:06,809
And they can learn a lot more from this image
than they can from this, so that is why scientists

606
00:48:06,809 --> 00:48:10,969
push to get good imaging resolution as well
as good spectroscopy.

607
00:48:10,969 --> 00:48:17,969
The biggest challenge for us on Chandra was
the mirrors.

608
00:48:20,430 --> 00:48:27,430
Now, recognize that due to the analysis that
we performed early on, yes, this was all theoretically

609
00:48:31,809 --> 00:48:37,059
possible, but we had to be able to polish
the surfaces of those mirrors, those grazing

610
00:48:37,059 --> 00:48:42,249
incidence mirrors to an accuracy of on the
order of angstroms.

611
00:48:42,249 --> 00:48:46,009
And that is pretty small.

612
00:48:46,009 --> 00:48:47,140
Can we measure that?

613
00:48:47,140 --> 00:48:48,559
The answer is no.

614
00:48:48,559 --> 00:48:54,269
At the time, we couldn't even measure how
accurately we needed to polish the mirrors.

615
00:48:54,269 --> 00:48:59,349
So that tells you that, boy, we've got our
work cut out.

616
00:48:59,349 --> 00:49:06,349
We had to work with the National Institute
for Standards to figure out how to first measure

617
00:49:08,269 --> 00:49:13,160
how accurately we can polish it and then ended
up polishing the mirrors.

618
00:49:13,160 --> 00:49:20,160
And polishing, as a process, getting down
to that smoothness clearly is a huge challenge

619
00:49:21,630 --> 00:49:23,539
and takes a long time.

620
00:49:23,539 --> 00:49:28,999
And so, that was probably our biggest challenge,
is to polish the mirrors.

621
00:49:28,999 --> 00:49:35,999
Metrology is the science of working mirror
technology and getting the surface figure

622
00:49:39,109 --> 00:49:41,680
of the mirrors correct.

623
00:49:41,680 --> 00:49:48,680
So, really, the key to success is developing
three different types of metrology measurements

624
00:49:49,779 --> 00:49:52,979
that are independent, that allow you to cross-check.

625
00:49:52,979 --> 00:49:58,150
Because you are talking about things you have
never built before and you are pushing the

626
00:49:58,150 --> 00:50:02,269
state of the art and you don't know how to
measure it.

627
00:50:02,269 --> 00:50:09,269
The key there for an engineer should say,
OK, I need not just one way of checking my

628
00:50:10,059 --> 00:50:17,059
work, but I need at least two ways, and preferably
three independent ways of making sure that

629
00:50:17,380 --> 00:50:19,380
I am doing the right thing.

630
00:50:19,380 --> 00:50:25,869
So when you're pushing the state of the art,
a good lesson is try and get into a position

631
00:50:25,869 --> 00:50:32,259
where you have got more than one independent
check of your analysis to make sure it is

632
00:50:32,259 --> 00:50:33,599
correct.

633
00:50:33,599 --> 00:50:35,640
So that was a very big challenge for us.

634
00:50:35,640 --> 00:50:40,749
And, again, that is kind of how it goes down.

635
00:50:40,749 --> 00:50:47,749
This is the general shape of the mirrors.

636
00:50:48,559 --> 00:50:52,589
And here are the mirror pairs being assembled.

637
00:50:52,589 --> 00:50:57,229
And, of course, one thing about the mirrors
is when you are talking about that surface

638
00:50:57,229 --> 00:51:03,239
finish, you cannot just assemble it in your
garage with dust around.

639
00:51:03,239 --> 00:51:06,410
You have to be extremely clean.

640
00:51:06,410 --> 00:51:12,489
And, believe it or not, one of the dirtiest
things in a laboratory is a human.

641
00:51:12,489 --> 00:51:19,489
And so, a human has to be almost completely
covered to prevent any kind of accumulation

642
00:51:19,940 --> 00:51:21,339
on the mirrors themselves.

643
00:51:21,339 --> 00:51:28,190
In fact, we had to limit the exposure time
of humans to the unpolished and polished mirrors

644
00:51:28,190 --> 00:51:35,190
during this timeframe because contamination
is an incredible problem when you are talking

645
00:51:35,529 --> 00:51:42,529
about the atomic scales of polishing the mirrors.

646
00:51:43,979 --> 00:51:49,670
Again, I mention that the important thing
is to make sure that you are doing cross-checks

647
00:51:49,670 --> 00:51:51,969
in the metrology as you are going along.

648
00:51:51,969 --> 00:51:54,650
Because, again, you don't know exactly what
you are doing.

649
00:51:54,650 --> 00:51:59,469
I mean on paper, yes, you've got an analytical
solution that tells you the right answer,

650
00:51:59,469 --> 00:52:00,660
but you have never done it before.

651
00:52:00,660 --> 00:52:01,769
You have never built it before.

652
00:52:01,769 --> 00:52:03,489
You don't know how to measure it.

653
00:52:03,489 --> 00:52:09,170
So you have got to work on building confidence
that your analysis is correct.

654
00:52:09,170 --> 00:52:11,920
How do I know that analysis is correct?

655
00:52:11,920 --> 00:52:18,479
And so, you have got to think about a sanity
check, if you will, to make sure that those

656
00:52:18,479 --> 00:52:20,130
are correct.

657
00:52:20,130 --> 00:52:25,719
And, of course, the best way for proving that
it is correct is test them.

658
00:52:25,719 --> 00:52:27,849
And that is what we did.

659
00:52:27,849 --> 00:52:30,819
Mandated by Congress, we tested the mirrors.

660
00:52:30,819 --> 00:52:33,890
Now, the thing about that is so I test the
mirrors.

661
00:52:33,890 --> 00:52:40,890
I am testing the mirrors in a 1G environment
so, even after the test, how do I know that

662
00:52:41,239 --> 00:52:44,079
those results are correct?

663
00:52:44,079 --> 00:52:48,979
Because the 1G deflection, even though you
think it is small, it does affect the mirror

664
00:52:48,979 --> 00:52:51,609
performance on the ground versus in orbit.

665
00:52:51,609 --> 00:52:54,380
And another thing is the finite source distance.

666
00:52:54,380 --> 00:53:01,380
You cannot get a source that is infinitely
far away on the ground just because of the

667
00:53:01,930 --> 00:53:03,700
nature of putting a source out there.

668
00:53:03,700 --> 00:53:10,700
Our source was about, I think, a quarter mile
away.

669
00:53:10,849 --> 00:53:17,670
And we had to make analytical corrections
to compensate for how we expected the spot

670
00:53:17,670 --> 00:53:21,069
size to change because of that finite source
distance.

671
00:53:21,069 --> 00:53:28,069
We had to analytically correct the image on
the ground to compensate for the 1G affects

672
00:53:28,769 --> 00:53:30,269
of the mirrors.

673
00:53:30,269 --> 00:53:32,650
And so, even a test you would think, OK, go
test it.

674
00:53:32,650 --> 00:53:37,489
Well, it is not straightforward because, even
in that test, that is not a true representation

675
00:53:37,489 --> 00:53:39,910
of how it would work on orbit.

676
00:53:39,910 --> 00:53:44,089
So it is a lot more complicated than one would
think.

677
00:53:44,089 --> 00:53:48,380
What do you use your x-rays for?

678
00:53:48,380 --> 00:53:51,390
Various things.

679
00:53:51,390 --> 00:53:56,509
We had some monochromatic x-rays at various
wavelengths.

680
00:53:56,509 --> 00:53:58,219
We had registration x-rays.

681
00:53:58,219 --> 00:53:59,390
Iron.

682
00:53:59,390 --> 00:54:02,599
A certain wavelength of iron is a big one
to use.

683
00:54:02,599 --> 00:54:05,779
You don't have a picture of the big tunnel,
do you?

684
00:54:05,779 --> 00:54:06,599
I think I do in here.

685
00:54:06,599 --> 00:54:08,319
I have got a picture of it and I can talk
about.

686
00:54:08,319 --> 00:54:15,200
But that is another thing, is when you are
testing, how well do I know my source?

687
00:54:15,200 --> 00:54:19,079
And that is all factored into verifying that
you have got the performance correct, because

688
00:54:19,079 --> 00:54:23,829
if your source is all over the place and you
haven't characterized your source well enough

689
00:54:23,829 --> 00:54:30,829
then how in the world can you say that the
mirrors are that good?

690
00:54:32,890 --> 00:54:34,049
So we did end-to-end testing.

691
00:54:34,049 --> 00:54:39,499
And, again, you don't just look at the raw
data and say, yeah, I am there.

692
00:54:39,499 --> 00:54:45,559
Even in the ground test, a lot of times you
have to massage the data and compensate analytically

693
00:54:45,559 --> 00:54:49,779
for factors that you cannot control.

694
00:54:49,779 --> 00:54:54,859
And the key to success there is good systems
engineering.

695
00:54:54,859 --> 00:54:59,349
And a lot of that is because of multiple separate
parties, academia, nonprofits and foreign

696
00:54:59,349 --> 00:55:02,940
groups all involved in the workings of AXAF.

697
00:55:02,940 --> 00:55:06,209
You have got to make sure that you have got
a team that works together.

698
00:55:06,209 --> 00:55:12,549
Lesson learned, as I had mentioned, perform
multiple cross-checks either via test or analysis

699
00:55:12,549 --> 00:55:15,059
with a different tool as possible.

700
00:55:15,059 --> 00:55:19,130
Another lesson learned is let more than one
group perform the review.

701
00:55:19,130 --> 00:55:26,130
A lot of times, for Chandra, we had the Marshall
engineers, but we also contracted SAO down

702
00:55:26,239 --> 00:55:33,239
the street to kind of independently assess,
using their own software tools, where we were.

703
00:55:33,450 --> 00:55:38,209
And that was a good idea because sometimes
we had good ideas that we could incorporate

704
00:55:38,209 --> 00:55:43,180
and sometimes they had good ideas, but it
gave us a sanity check when we both matches

705
00:55:43,180 --> 00:55:44,319
and we both felt good.

706
00:55:44,319 --> 00:55:49,809
There is also no substitute for direct test
or measurement.

707
00:55:49,809 --> 00:55:56,809
Analytically, we have wonderful tools nowadays,
but they will never take the place of testing.

708
00:55:57,559 --> 00:56:03,039
Another thing that was very important for
us because of the iteration cycle with headquarters

709
00:56:03,039 --> 00:56:09,039
on funding is make sure that you keep the
science or the scientists that are part of

710
00:56:09,039 --> 00:56:14,269
the mission informed and part of the decision-making
process.

711
00:56:14,269 --> 00:56:18,880
One would think, and one would like to think
that this is a technical project, all things

712
00:56:18,880 --> 00:56:20,309
are technical.

713
00:56:20,309 --> 00:56:25,009
No, there are personalities involved and there
are human responses involved.

714
00:56:25,009 --> 00:56:30,910
And so, to keep the team together you need
make sure that the science is informed and

715
00:56:30,910 --> 00:56:33,059
supporting your decision-making process.

716
00:56:33,059 --> 00:56:40,059
A lot of times that is overlooked, but it
is, nonetheless, very important as you are

717
00:56:40,309 --> 00:56:41,859
building a project.

718
00:56:41,859 --> 00:56:48,859
And the final lesson learned is, as we are
going through and making those mirrors, you

719
00:56:49,190 --> 00:56:53,789
construct what is called an error budget.

720
00:56:53,789 --> 00:56:57,709
You assume perfect performance and then you
kind of step back and say I am going to allow

721
00:56:57,709 --> 00:57:01,749
imperfect performance in this region.

722
00:57:01,749 --> 00:57:05,309
And I am going to allocate that imperfect
performance to thermal design.

723
00:57:05,309 --> 00:57:12,309
I am going to allocate imperfect performance
to the inaccurate knowledge of knowing the

724
00:57:12,579 --> 00:57:14,579
source positions in the sky.

725
00:57:14,579 --> 00:57:21,440
I am going to allocate some error budget to
flexing of the optical bench.

726
00:57:21,440 --> 00:57:28,440
I am going to allocate some error sources
to the difference between how long the focal

727
00:57:28,690 --> 00:57:32,190
length is and how long I think it is.

728
00:57:32,190 --> 00:57:33,930
And so, you take each of the error terms.

729
00:57:33,930 --> 00:57:37,869
And for Chandra we probably had a hundred
or more.

730
00:57:37,869 --> 00:57:44,160
And you go through and you verify that your
assumption in that error budget term was correct.

731
00:57:44,160 --> 00:57:48,989
And usually, for the critical ones, you did
it in more than one way, more than one method

732
00:57:48,989 --> 00:57:54,309
so that you were sure that you had those error
terms defined.

733
00:57:54,309 --> 00:57:58,469
And the end result was we had mirrors that
performed better than expected.

734
00:57:58,469 --> 00:58:05,469
And, as a result, the payoff is just wonderful.

735
00:58:09,329 --> 00:58:12,789
This is a time-lapse series of images.

736
00:58:12,789 --> 00:58:19,789
And, supposedly, this wave front was moving
out from the source pulsar at significant

737
00:58:23,599 --> 00:58:28,579
fractions of the speed of light on the order
of 20% to 30% of the speed of light.

738
00:58:28,579 --> 00:58:29,599
That was pretty cool.

739
00:58:29,599 --> 00:58:31,809
And if you need more information just talk
to Jeff.

740
00:58:31,809 --> 00:58:38,809
But that was a pretty big payoff.

741
00:58:42,079 --> 00:58:46,619
The next challenge that we had was the programmatic
challenge.

742
00:58:46,619 --> 00:58:53,489
Again, as I had mentioned, the normal process
of going through a program in a project is

743
00:58:53,489 --> 00:58:56,400
you are first trying to size the mission.

744
00:58:56,400 --> 00:58:59,380
And, really, you are sizing it for cost.

745
00:58:59,380 --> 00:59:02,880
And that is very hard to do when you are building
something new.

746
00:59:02,880 --> 00:59:07,459
And that was a very big challenge.

747
00:59:07,459 --> 00:59:10,880
And so, we changed a lot of things.

748
00:59:10,880 --> 00:59:17,739
But, eventually, the key or the critical thing
that you are trying to do is I compromise

749
00:59:17,739 --> 00:59:21,359
on this but I want to still try and maintain
performance.

750
00:59:21,359 --> 00:59:27,890
We maintained our imaging resolution performance
and our registration performance.

751
00:59:27,890 --> 00:59:32,119
And we compromised on a few other things but
we maintained that performance.

752
00:59:32,119 --> 00:59:39,119
Finish this slide and then we will take a
quick break.

753
00:59:41,309 --> 00:59:48,309
Note down here that we also needed to reduce
the weight by a factor of two from our original

754
00:59:50,880 --> 00:59:51,989
designs.

755
00:59:51,989 --> 00:59:56,089
Our original designs were pretty simple aluminum
structures.

756
00:59:56,089 --> 01:00:02,019
Our final designs were the best composites
that we knew how to make at lowest weight.

757
01:00:02,019 --> 01:00:07,430
And so, that optical bench, that tube was
all composite.

758
01:00:07,430 --> 01:00:13,789
And so, that is the kind of weight reduction
scheme we had to go through.

759
01:00:13,789 --> 01:00:18,749
Now, also all of the fittings, that means
all of the brackets that we use were also

760
01:00:18,749 --> 01:00:20,059
composite.

761
01:00:20,059 --> 01:00:27,059
And another challenge that we had is analyzing
the stresses in a complicated composite fitting.

762
01:00:29,999 --> 01:00:30,479
Very hard to do.

763
01:00:30,479 --> 01:00:35,829
Didn't have techniques to do it when we started.

764
01:00:35,829 --> 01:00:41,299
As part of the process of building this telescope,
we had to go through and learn that and develop

765
01:00:41,299 --> 01:00:42,029
those techniques.

766
01:00:42,029 --> 01:00:49,029
Before the break, I just want to point out
I hope you all are catching the incredible

767
01:00:51,410 --> 01:00:58,309
parallels between this project, a complex
technological process and the sorts of things

768
01:00:58,309 --> 01:01:01,180
that we've heard about the systems engineering
of the Shuttle.

769
01:01:01,180 --> 01:01:08,180
Right from the weight problems and composites,
new materials, new ways of analysis right

770
01:01:10,719 --> 01:01:16,609
into the intervention of Congress into the
engineering process, I mean it is all there.

771
01:01:16,609 --> 01:01:22,969
And I think whenever you get involved in a
big space project you can expect that those

772
01:01:22,969 --> 01:01:29,019
things are going to happen, and they are probably
going to happen in the Exploration Program

773
01:01:29,019 --> 01:01:29,369
as well.

774
01:01:29,369 --> 01:01:33,940
Two minute break and then we will start up
again.

775
01:01:33,940 --> 01:01:38,380
Start up again.

776
01:01:38,380 --> 01:01:41,339
Let's see.

777
01:01:41,339 --> 01:01:48,339
We were talking about for us the next biggest
challenge was programmatic in that it you

778
01:01:53,059 --> 01:01:55,180
have to work that early on.

779
01:01:55,180 --> 01:02:00,589
And typically, especially the more expensive
missions do go through this as a typical part

780
01:02:00,589 --> 01:02:02,410
of the lifecycle of a project.

781
01:02:02,410 --> 01:02:07,150
I have a question on that last slide.

782
01:02:07,150 --> 01:02:09,670
[NOISE OBSCURES]

783
01:02:09,670 --> 01:02:15,579
The budget for systems engineering was cut
which translates directly to the number of

784
01:02:15,579 --> 01:02:18,109
folks at the contractor site.

785
01:02:18,109 --> 01:02:22,130
Working systems engineering was cut so we
were challenged.

786
01:02:22,130 --> 01:02:29,130
And what we did at Marshall was we offset
with NASA's civil servants doing functions

787
01:02:30,130 --> 01:02:35,160
and tasks that the contractor would normally
do to compensate for that.

788
01:02:35,160 --> 01:02:38,359
So that is what that meant.

789
01:02:38,359 --> 01:02:45,359
Typically, systems engineering, a very important
thing if you talk to folks in the trade, almost

790
01:02:45,459 --> 01:02:50,059
everyone has a different idea of what all
is encompassed in systems engineering.

791
01:02:50,059 --> 01:02:55,180
But the point is there probably are a number
of things that almost everybody would agree

792
01:02:55,180 --> 01:02:56,709
are part of systems engineering.

793
01:02:56,709 --> 01:03:00,349
And they are very key to executing the program
and the project.

794
01:03:00,349 --> 01:03:02,869
They are really the glue that holds all the
subsystems together.

795
01:03:02,869 --> 01:03:09,869
And I will probably talk more about it, but
for good systems engineers you have to be

796
01:03:11,809 --> 01:03:17,799
able to communicate well with all the other
subsystems and all the other stakeholders,

797
01:03:17,799 --> 01:03:22,479
including the science when you have a science
mission, including the users when you have

798
01:03:22,479 --> 01:03:28,729
a manned mission, including safety and everybody
to make sure they are all connected.

799
01:03:28,729 --> 01:03:35,729
And be smart enough to be able to challenge
the subsystems when they really have their

800
01:03:36,369 --> 01:03:43,369
own ideas on where this needs to go and it
is not really in concert with everybody else.

801
01:03:49,869 --> 01:03:56,609
Weight reduction did have some impacts, as
I mentioned, using light-weight composites.

802
01:03:56,609 --> 01:03:59,640
And that was a challenge in and of itself.

803
01:03:59,640 --> 01:04:05,089
We also dropped two of the SIs.

804
01:04:05,089 --> 01:04:09,359
Another challenge was the science instrument
module which was all composite.

805
01:04:09,359 --> 01:04:16,359
And it had the capability of adjusting focus
and translating, so it had two degrees of

806
01:04:17,170 --> 01:04:17,619
freedom.

807
01:04:17,619 --> 01:04:24,619
But it needed to be reproducible in terms
of motion on the micron scale over the whole

808
01:04:28,469 --> 01:04:30,339
orbit environment.

809
01:04:30,339 --> 01:04:34,420
That was quite a challenge in and of itself
to be able to do that.

810
01:04:34,420 --> 01:04:41,420
I mean just kind of a flavor for the things
that you have to deal with is not everybody

811
01:04:43,469 --> 01:04:50,469
had the same analysis tools so universities
like MIT and like SAO had different structural

812
01:04:51,170 --> 01:04:56,440
analysis tools for their hardware than the
contractors did.

813
01:04:56,440 --> 01:05:03,440
Now you do a couple loads analysis, which
is you pull together all of your stress, all

814
01:05:04,759 --> 01:05:11,759
of your structure analysis models together
in one place and you go through a loads assessment

815
01:05:13,319 --> 01:05:14,489
all through the whole element.

816
01:05:14,489 --> 01:05:21,009
Well, to do that I need a model from you,
I need a model from you, I need a model from

817
01:05:21,009 --> 01:05:21,259
you.
But you are in California, you are a university,
you are another company and you have to make

818
01:05:30,199 --> 01:05:32,219
sure they all play together.

819
01:05:32,219 --> 01:05:36,459
And a lot of times there is parochialness
with company A, I am not going to use anything

820
01:05:36,459 --> 01:05:37,369
but my model.

821
01:05:37,369 --> 01:05:42,529
And the university says, well, I cannot do
anything but what we have been doing.

822
01:05:42,529 --> 01:05:46,910
And university C says, well, this is the only
thing that will work and you guys are crazy.

823
01:05:46,910 --> 01:05:51,829
It is not that bad but that is the kind of
thing that you have to deal with as a systems

824
01:05:51,829 --> 01:05:52,249
engineer.

825
01:05:52,249 --> 01:05:54,359
You have to make sure everybody plays together.

826
01:05:54,359 --> 01:06:01,359
And sometimes you have to go through and work
the best solution that may not be the optimum

827
01:06:01,469 --> 01:06:02,910
solution for each piece.

828
01:06:02,910 --> 01:06:09,910
But it is the optimum solution for the overall
answer.

829
01:06:13,809 --> 01:06:20,809
Again, getting the programmatic challenge
behind us, a key thing is also setting allocations.

830
01:06:24,559 --> 01:06:26,130
I talk about the error budgets.

831
01:06:26,130 --> 01:06:33,130
Another good thing that the systems engineer
does is allocates various important resources.

832
01:06:34,049 --> 01:06:37,469
And one that every spacecraft does is weight.

833
01:06:37,469 --> 01:06:44,469
Weight, power and data are usually three of
the important resources that are allocated.

834
01:06:45,369 --> 01:06:52,369
For scientific telescope missions another
one is error budgets for scientific performance,

835
01:06:53,940 --> 01:07:00,940
but the key to that is good weight allocation
and good iteration, which with each of the

836
01:07:02,529 --> 01:07:08,229
elements that you allocated the weight to,
to keep up with them to make sure they can

837
01:07:08,229 --> 01:07:11,180
meet that or it looks like they are going
to exceed.

838
01:07:11,180 --> 01:07:16,739
So I have got to go borrow some of that allocation
from somebody else.

839
01:07:16,739 --> 01:07:21,719
And I have got to take away from Peter, if
you will, to pay Paul.

840
01:07:21,719 --> 01:07:27,890
So systems engineering and going through that
making the initial allocations and keeping

841
01:07:27,890 --> 01:07:33,890
up with that is a pretty critical factor to
making sure you get to the final answer.

842
01:07:33,890 --> 01:07:40,890
And, if you do that well, then usually you
have less of a problem getting to the final

843
01:07:42,499 --> 01:07:45,279
solution.

844
01:07:45,279 --> 01:07:52,279
To compensate for the loss of systems engineering,
we established technical oversight panels

845
01:07:53,229 --> 01:07:58,430
which were NASA employees at our center.

846
01:07:58,430 --> 01:08:04,538
We controlled, at a project level, the internal
ICDs.

847
01:08:04,538 --> 01:08:05,400
Now, what is an ICD?

848
01:08:05,400 --> 01:08:08,180
It is an interface control drawing.

849
01:08:08,180 --> 01:08:15,180
Because when you have company A developing
an element and university A, where they come

850
01:08:17,589 --> 01:08:18,859
together is an interface.

851
01:08:18,859 --> 01:08:24,339
And you have to document that interface, not
just mechanically but thermally.

852
01:08:24,339 --> 01:08:28,510
What is the heat flow across the interface,
the data across the interface, the power,

853
01:08:28,510 --> 01:08:32,120
the signal characteristics across the interface?

854
01:08:32,120 --> 01:08:33,190
The data flow.

855
01:08:33,190 --> 01:08:37,080
What data is going across the interface?

856
01:08:37,080 --> 01:08:42,779
And, as you can realize, as both of those
things change, you have to change the interface.

857
01:08:42,779 --> 01:08:45,970
So you have to keep up with that.

858
01:08:45,970 --> 01:08:52,970
And a lot of times good systems engineers
will recognize the further away in location

859
01:08:54,229 --> 01:08:58,950
it is the harder it is to interface with the
two parties.

860
01:08:58,950 --> 01:09:05,430
When you are in California it is one thing
when they are in the same town, it is another

861
01:09:05,430 --> 01:09:09,690
thing when they are in the same country and
it is another thing where they are across

862
01:09:09,690 --> 01:09:14,220
the water when you are integrating an international
partner.

863
01:09:14,220 --> 01:09:19,700
So, as systems engineers, the factor is the
closer you are the better it is because I

864
01:09:19,700 --> 01:09:26,700
can just go in a car and go across town to
get out the drawings and talk about the drawings

865
01:09:26,870 --> 01:09:33,068
versus in California that is a plane ride.

866
01:09:33,068 --> 01:09:40,068
But, in Europe, the time difference allows
you to only be able to talk to them for a

867
01:09:40,250 --> 01:09:44,370
few hours a day because that is when your
work shifts overlap.

868
01:09:44,370 --> 01:09:48,710
So it is a lot more complicated interacting
with folks in Europe, interacting with folks

869
01:09:48,710 --> 01:09:55,710
in Japan, in India because of the time difference
and because it is very far away when you have

870
01:09:56,070 --> 01:09:57,770
to sit down.

871
01:09:57,770 --> 01:10:04,770
Those are kind of the challenges as systems
engineers that you should think about.

872
01:10:06,309 --> 01:10:07,460
Lessons learned.

873
01:10:07,460 --> 01:10:13,070
Set your resource allocations early and continue
to monitor them and work with each of the

874
01:10:13,070 --> 01:10:20,070
owners of the elements of those allocations
to make sure that they are meeting their allocation.

875
01:10:21,059 --> 01:10:25,900
As you recognize, it is a zero sum gain.

876
01:10:25,900 --> 01:10:31,550
So when somebody goes over their allocation
somebody has got to be reduced.

877
01:10:31,550 --> 01:10:38,550
And it is very difficult sometimes to negotiate
that reduction because engineers typically

878
01:10:40,330 --> 01:10:42,690
want to hold their margin, they don't want
to release it.

879
01:10:42,690 --> 01:10:47,880
They want it because they are not yet confident
in their final solution.

880
01:10:47,880 --> 01:10:52,280
But to make everything play sometimes you
have to take away from them and reduce their

881
01:10:52,280 --> 01:10:57,250
margin to be able to let somebody else survive
if you will.

882
01:10:57,250 --> 01:11:04,250
It is not an easy thing, but attention to
that detail is important.

883
01:11:09,000 --> 01:11:13,270
Maintaining strong systems engineering group
is important for that reason.

884
01:11:13,270 --> 01:11:19,820
If I have a lot of pretty dominant subsystem
managers that say I am building a power system

885
01:11:19,820 --> 01:11:26,370
and I need this much weight and I need this
much thermal capability that's good, and they

886
01:11:26,370 --> 01:11:31,390
may be very good, but what they are doing
is if you have a lot of dominant subsystems

887
01:11:31,390 --> 01:11:36,800
and no central systems engineering, as traffic
cop there is no check and balance.

888
01:11:36,800 --> 01:11:43,370
And so that dominant thing may work very well
at the expense of the integrated performance

889
01:11:43,370 --> 01:11:44,170
of everybody else.

890
01:11:44,170 --> 01:11:51,170
That is why systems engineering is so important,
that dominance and to balance weakness where

891
01:11:51,350 --> 01:11:57,230
you have weakness.

892
01:11:57,230 --> 01:12:04,230
And for Chandra hard work pays off when you
get it right.

893
01:12:08,040 --> 01:12:09,860
Technology.

894
01:12:09,860 --> 01:12:16,860
A lot of times NASA will build a science spacecraft.

895
01:12:17,270 --> 01:12:22,110
And the spacecraft itself usually isn't pushing
a state of the art.

896
01:12:22,110 --> 01:12:23,730
For Chandra it was a little different.

897
01:12:23,730 --> 01:12:28,010
We pushed the mirrors, and there are a few
other things we pushed.

898
01:12:28,010 --> 01:12:33,350
But typically it is the case where NASA pushes
the state of the art on the instruments.

899
01:12:33,350 --> 01:12:37,140
Better sensors, better CCDs, better processing
electronics.

900
01:12:37,140 --> 01:12:40,390
And Chandra was no different.

901
01:12:40,390 --> 01:12:45,910
Usually it is an embellishment from something
that has flown before on a different spacecraft,

902
01:12:45,910 --> 01:12:47,050
only now it is better.

903
01:12:47,050 --> 01:12:48,230
We are getting it bigger.

904
01:12:48,230 --> 01:12:51,830
We are getting more resolution.

905
01:12:51,830 --> 01:12:55,340
It takes less power.

906
01:12:55,340 --> 01:12:58,230
There is usually a steppingstone.

907
01:12:58,230 --> 01:13:05,230
And for ASIS, the one that was built at MIT,
it charged a couple of devices in an array

908
01:13:06,110 --> 01:13:08,830
size that they have never been built before.

909
01:13:08,830 --> 01:13:10,960
And so that was a challenge.

910
01:13:10,960 --> 01:13:17,809
Also a challenge was in order for the CCDs
to operate they needed to be cooled to minus

911
01:13:17,809 --> 01:13:24,210
100 degrees Celsius, 120.

912
01:13:24,210 --> 01:13:31,210
And, in addition, they developed a new way
of clocking out the data from the rest of

913
01:13:32,710 --> 01:13:35,780
the CCDs that have been built.

914
01:13:35,780 --> 01:13:41,750
That had better spectroscopy performance and
a very low noise signal chain.

915
01:13:41,750 --> 01:13:48,160
There are always going and they are always
looking at, well, on spacecraft X this CCD

916
01:13:48,160 --> 01:13:48,750
was flown.

917
01:13:48,750 --> 01:13:51,140
It may have been a 512 x 512.

918
01:13:51,140 --> 01:13:52,580
Well, you know, it is pretty easy.

919
01:13:52,580 --> 01:13:57,600
I can stretch it a little bit and work the
substrate in 24 x 24.

920
01:13:57,600 --> 01:14:00,920
Well, usually it is the case where it is not
as simple as you think.

921
01:14:00,920 --> 01:14:06,290
And there are always problems.

922
01:14:06,290 --> 01:14:11,170
In particular, technology should be a warning
flag to systems engineers to say typically

923
01:14:11,170 --> 01:14:18,170
it is not as simple as you think so make sure
you are paying attention to these new developments

924
01:14:18,270 --> 01:14:24,400
or these stretching of new applications of
existing technology.

925
01:14:24,400 --> 01:14:31,400
Because, for instance, one of the things that
you get bit by, and we got bit by is radiation

926
01:14:32,600 --> 01:14:35,059
susceptibility.

927
01:14:35,059 --> 01:14:41,140
Thermal extremes for multilayer circuit cards
that have to operate at minus 120 C on one

928
01:14:41,140 --> 01:14:45,690
end and room temperature on another end.

929
01:14:45,690 --> 01:14:48,120
Low yields for those new types of CCDs.

930
01:14:48,120 --> 01:14:55,120
I can just stretch it and make it 1024 x 1024,
but where I was using 90% of the batch, now

931
01:14:55,710 --> 01:15:02,450
I am only using 10% just because I cannot
get one that big to work out and to be smooth

932
01:15:02,450 --> 01:15:05,740
and homogenous.

933
01:15:05,740 --> 01:15:09,020
ESD sensitivity.

934
01:15:09,020 --> 01:15:14,510
Because they are getting bigger and bigger
and thinner and thinner it is much more susceptible

935
01:15:14,510 --> 01:15:16,750
to electrostatic discharge.

936
01:15:16,750 --> 01:15:23,750
And simple things like my yield in the wintertime,
because the humidity in the air is lower,

937
01:15:27,390 --> 01:15:30,890
I have less of a yield in winter than I do
in summer.

938
01:15:30,890 --> 01:15:34,450
And so that is what we found out.

939
01:15:34,450 --> 01:15:40,040
And there are also mitigating effects that
you can come and put humidifiers in and compensate

940
01:15:40,040 --> 01:15:41,460
for that.

941
01:15:41,460 --> 01:15:45,970
But those are the types of things that you
have to worry about that can come and bite

942
01:15:45,970 --> 01:15:52,970
you with new technology because you are doing
something new.

943
01:15:53,460 --> 01:15:59,410
Because of going down to 120 to optimize the
performance and to get the very low noise,

944
01:15:59,410 --> 01:16:02,650
we said we need a radiator or a sunshade.

945
01:16:02,650 --> 01:16:09,650
And, low and behold, flying on the Shuttle
in certain attitudes that you have to verify,

946
01:16:11,050 --> 01:16:18,050
because in some off nominal events you can,
instead of being deployed on day one of a

947
01:16:19,790 --> 01:16:26,790
mission you get deployed on day three, but
you have to go across the sun terminator frequently

948
01:16:27,650 --> 01:16:32,520
and you get a little glint of direct sunlight
on these sunshades.

949
01:16:32,520 --> 01:16:37,040
And, therefore, you have to analyze what the
temperature extreme and what the effect is

950
01:16:37,040 --> 01:16:37,480
going to be.

951
01:16:37,480 --> 01:16:41,780
And, low and behold, we see that we have delamination
on that case.

952
01:16:41,780 --> 01:16:48,040
But here is a case where it is an off nominal
event in the Shuttle that we have to design

953
01:16:48,040 --> 01:16:52,290
for and we have to compensate for, even though
chances are we will never see that design

954
01:16:52,290 --> 01:16:55,150
case.

955
01:16:55,150 --> 01:17:02,150
But a lot of times the programmer or project
manager has to say I am going to suck it up

956
01:17:03,780 --> 01:17:07,580
and I am going to make the change for that
small eventuality.

957
01:17:07,580 --> 01:17:14,580
Or I am going to risk it based on cost and
we are going to try and preclude that eventuality

958
01:17:15,860 --> 01:17:17,920
from happening.

959
01:17:17,920 --> 01:17:20,480
A lot of times it is not cut and dry.

960
01:17:20,480 --> 01:17:21,340
It is a guessing game.

961
01:17:21,340 --> 01:17:25,230
It is a balance that is based on judgment,
past performance and a lot of other factors

962
01:17:25,230 --> 01:17:32,230
to say, boy, that is so low probability of
occurrence that I am not going to worry about

963
01:17:36,090 --> 01:17:36,559
it.

964
01:17:36,559 --> 01:17:39,550
And that threshold is never defined.

965
01:17:39,550 --> 01:17:46,550
You have to define it as a project manager.

966
01:17:48,330 --> 01:17:51,150
Just kind of a picture of what the instruments
look like.

967
01:17:51,150 --> 01:17:52,690
There are the CCDs.

968
01:17:52,690 --> 01:17:54,900
This is the long stretched away.

969
01:17:54,900 --> 01:18:01,900
And, for the spectroscopy measurements, that
is where the lower energies -- Actually, the

970
01:18:03,480 --> 01:18:08,980
higher energies in the middle and the lower
energies go along this wing and along this

971
01:18:08,980 --> 01:18:12,020
wing because you get the energy spread.

972
01:18:12,020 --> 01:18:19,020
And there are the imaging devices that are
used when you just want a good image.

973
01:18:20,000 --> 01:18:24,710
On HRC, there is the detector right there
in this diamond-shaped thing.

974
01:18:24,710 --> 01:18:31,370
And it is operating off a completely new and
older technology than the CCDs.

975
01:18:31,370 --> 01:18:38,370
The instrument of choice has been this for
probably 70%, 75% of the observations just

976
01:18:40,210 --> 01:18:46,900
because of the capability that this allows
you not just an image, but the CCDs also give

977
01:18:46,900 --> 01:18:51,020
you some rudimentary information on energy.

978
01:18:51,020 --> 01:18:58,020
And so, that is why this is preferable over
this one.

979
01:19:02,150 --> 01:19:05,559
On HRC, we talked about ASIS.

980
01:19:05,559 --> 01:19:09,760
We had, again, a low noise signal chain.

981
01:19:09,760 --> 01:19:14,440
On HRC, we never had three micro channel plates
tied together and linked together.

982
01:19:14,440 --> 01:19:16,370
And we had that challenge.

983
01:19:16,370 --> 01:19:18,930
We also had very accurate event timing.

984
01:19:18,930 --> 01:19:25,930
So, when we have a pulsar, I know exactly
in registered time when those pulses are occurring.

985
01:19:30,180 --> 01:19:37,180
We had spacecraft charging protection for
new technology problems and spurious noise

986
01:19:37,260 --> 01:19:38,809
susceptibility.

987
01:19:38,809 --> 01:19:41,190
Spacecraft charging.

988
01:19:41,190 --> 01:19:48,190
To keep the mirrors nice and warm at plus
or minus half a degree C across the entire

989
01:19:48,960 --> 01:19:54,710
mirror surface all around it required thermal
blankets on the outside.

990
01:19:54,710 --> 01:20:01,090
Well, the thermal blankets were susceptible
to charging up and discharge with popping.

991
01:20:01,090 --> 01:20:08,090
And so, the question is, is that going to
affect my instrument performance by incorrectly

992
01:20:09,070 --> 01:20:14,350
registering a photon event every time these
blankets discharged?

993
01:20:14,350 --> 01:20:21,210
So we had to go through a test campaign to
verify that, no, this discharging of those

994
01:20:21,210 --> 01:20:28,210
blanket electrostatically would not affect
the imaging performance at the detector level.

995
01:20:29,630 --> 01:20:31,330
That is something we didn't even think about
before.

996
01:20:31,330 --> 01:20:35,240
But, low and behold, we came up with it.

997
01:20:35,240 --> 01:20:40,790
Yes, these things are going to discharge,
they are going to pop so is it going to affect

998
01:20:40,790 --> 01:20:41,650
our measurements.

999
01:20:41,650 --> 01:20:48,650
Those are the kinds of things that you will
run into.

1000
01:20:52,270 --> 01:20:56,020
Again, good systems engineering and sound
communications are the key to getting through

1001
01:20:56,020 --> 01:20:57,790
those.

1002
01:20:57,790 --> 01:20:59,830
Insuring participating.

1003
01:20:59,830 --> 01:21:02,080
Keeping parties informed.

1004
01:21:02,080 --> 01:21:09,080
Encouraging teamwork to be part of the team
and to help contribute to its success.

1005
01:21:10,320 --> 01:21:16,230
Lesson learned is establish standing interface
working groups with mandatory participation

1006
01:21:16,230 --> 01:21:17,040
from the SIs.

1007
01:21:17,040 --> 01:21:19,150
The SIs kind of have a different paradigm.

1008
01:21:19,150 --> 01:21:25,080
Science instruments are usually built by universities,
and the universities are typically staffed

1009
01:21:25,080 --> 01:21:32,080
by grad students and some full time engineers.

1010
01:21:32,400 --> 01:21:38,809
But usually the paradigm and the thinking
process is a university atmosphere.

1011
01:21:38,809 --> 01:21:45,580
When you have companies it is a completely
different interface, very regimented, very

1012
01:21:45,580 --> 01:21:49,100
by the book, we have done it before and this
is how you do it.

1013
01:21:49,100 --> 01:21:54,270
And so different cultures, you have to make
sure they blend together to produce the final

1014
01:21:54,270 --> 01:21:55,420
product.

1015
01:21:55,420 --> 01:21:57,059
And a lot of times that is not technical.

1016
01:21:57,059 --> 01:22:04,059
That is human interaction and making sure
they all work together.

1017
01:22:07,080 --> 01:22:13,100
When problems occur recognize that you need
to go outside of the project office to get

1018
01:22:13,100 --> 01:22:14,520
help.

1019
01:22:14,520 --> 01:22:16,980
And this is typically done at NASA.

1020
01:22:16,980 --> 01:22:23,980
If Marshall is managing a project and we have
got a problem with CCDs, the key to success

1021
01:22:27,890 --> 01:22:32,790
is recognize, well, Ames Research Center in
California has an expert in CCDs.

1022
01:22:32,790 --> 01:22:38,020
Call him up on the phone or bring him down
and let's talk to him to get his expertise

1023
01:22:38,020 --> 01:22:39,580
in on this project.

1024
01:22:39,580 --> 01:22:41,150
NASA does good on that.

1025
01:22:41,150 --> 01:22:44,809
It does go to where the expertise is.

1026
01:22:44,809 --> 01:22:49,600
Not just at another NASA center, but it may
call experts across the industry or across

1027
01:22:49,600 --> 01:22:52,350
academia to come help with a problem.

1028
01:22:52,350 --> 01:22:59,340
The foam problem on the Shuttle is a pretty
big problem, and we have called experts from

1029
01:22:59,340 --> 01:23:01,840
around the country and around the world to
try and help understand what was going on

1030
01:23:01,840 --> 01:23:05,050
with the foam.

1031
01:23:05,050 --> 01:23:09,280
That is something that NASA does well, is
it brings in experts and it doesn't think

1032
01:23:09,280 --> 01:23:12,130
that it knows everything locally.

1033
01:23:12,130 --> 01:23:14,150
And that is something to keep in mind.

1034
01:23:14,150 --> 01:23:17,070
If you don't know an answer, don't just try
and think of it yourself.

1035
01:23:17,070 --> 01:23:22,600
Go get the answers from somebody who might
have experienced that before.

1036
01:23:22,600 --> 01:23:24,430
And encourage teamwork.

1037
01:23:24,430 --> 01:23:30,790
A lot of times programs suffer from the culture
clash between different paradigms and different

1038
01:23:30,790 --> 01:23:31,040
cultures.
And that is especially the case between academia
and industry.

1039
01:23:36,690 --> 01:23:43,690
It is also evident between international partners
and industry.

1040
01:23:47,170 --> 01:23:54,170
And, of course, the payoff is this is a spectrogram,
the counts per bin, number of photons per

1041
01:23:54,910 --> 01:23:55,809
energy level.

1042
01:23:55,809 --> 01:24:02,809
And, as you can tell, very sharp and very
well-defined peaks for where those lines are.

1043
01:24:18,000 --> 01:24:20,920
Next challenge was integrated testing.

1044
01:24:20,920 --> 01:24:24,920
Integration is always a challenge.

1045
01:24:24,920 --> 01:24:27,460
How in the world are we going to integrate
this whole thing?

1046
01:24:27,460 --> 01:24:32,670
The logistics of who does what when, we must
choreograph it.

1047
01:24:32,670 --> 01:24:34,960
Here we have instrument A coming in.

1048
01:24:34,960 --> 01:24:36,190
We have instrument B.

1049
01:24:36,190 --> 01:24:38,520
We have the gratings coming in.

1050
01:24:38,520 --> 01:24:42,059
We have the ISIM built at Ball Brothers.

1051
01:24:42,059 --> 01:24:45,600
We have California building the optical bench.

1052
01:24:45,600 --> 01:24:51,440
Where are we all going to put this all together
and test it out?

1053
01:24:51,440 --> 01:24:56,100
That is always a challenge because, again,
you have different players involved in different

1054
01:24:56,100 --> 01:24:57,190
pieces.

1055
01:24:57,190 --> 01:24:59,370
And you have got to make sure it all plays
together.

1056
01:24:59,370 --> 01:25:06,300
And the key there is to create a working group
to make sure you address every aspect of integration.

1057
01:25:06,300 --> 01:25:08,080
You plan very much ahead of time.

1058
01:25:08,080 --> 01:25:15,080
You choreograph everybody coming in to make
sure you have got everything covered.

1059
01:25:16,120 --> 01:25:23,050
And in integration always, always it takes
longer than you think.

1060
01:25:23,050 --> 01:25:26,650
You always plan assuming nothing is going
to go wrong.

1061
01:25:26,650 --> 01:25:31,990
This test takes this long and this test takes
this long and this test takes this long.

1062
01:25:31,990 --> 01:25:37,309
When, in fact, as is always the case, you
always have problems in testing.

1063
01:25:37,309 --> 01:25:44,309
Any time you are matching two boxes together,
especially electronically, a lot of times

1064
01:25:45,370 --> 01:25:46,530
you have problems.

1065
01:25:46,530 --> 01:25:52,980
So testing is always something that you should
make sure you have enough time to do troubleshooting.

1066
01:25:52,980 --> 01:25:59,980
And plan for failures and not plan a success-oriented
schedule.

1067
01:26:05,780 --> 01:26:12,330
Even the best laid plans, TRW planned the
integrated testing in a vacuum chamber.

1068
01:26:12,330 --> 01:26:19,330
And during observatory integration TRW couldn't
hold the schedule because, guess what, the

1069
01:26:20,400 --> 01:26:26,390
first thing that goes when you are in a money
crunch is testing at the end.

1070
01:26:26,390 --> 01:26:28,040
And you say why do that?

1071
01:26:28,040 --> 01:26:35,040
Because they say we had six months of margin
in the schedule and you have eroded that margin.

1072
01:26:37,170 --> 01:26:40,480
But that margin you haven't really defined
anything to go into that margin.

1073
01:26:40,480 --> 01:26:46,150
So, hypothetically speaking, if everything
goes OK, I don't need that.

1074
01:26:46,150 --> 01:26:50,760
Well, so you take it off the table and it
gets eaten away.

1075
01:26:50,760 --> 01:26:51,809
And that is what happened.

1076
01:26:51,809 --> 01:26:58,460
It got eaten away and couldn't hold schedule
caused, in this case, by antiquated EGSE and

1077
01:26:58,460 --> 01:26:59,059
software.

1078
01:26:59,059 --> 01:27:03,820
But it is typical of a paradigm that says
I create schedule, you have got to try and

1079
01:27:03,820 --> 01:27:08,670
preserve this schedule and fight tooth and
nail to keep that reserve in every step of

1080
01:27:08,670 --> 01:27:14,530
the way because in integration test is where
usually you get behind.

1081
01:27:14,530 --> 01:27:20,059
When we got behind the recovery is daily focus
on schedule.

1082
01:27:20,059 --> 01:27:25,130
Every day we were on the phone going over
what was to occur that day.

1083
01:27:25,130 --> 01:27:32,130
24 hour operations one year before launch
continuing all the way around the clock.

1084
01:27:33,260 --> 01:27:37,380
We changed the I&T integration and test lead
out at TRW.

1085
01:27:37,380 --> 01:27:43,140
We brought Marshall NASA engineers into help
TRW do it.

1086
01:27:43,140 --> 01:27:49,840
And we had a technical presence help out at
the test site.

1087
01:27:49,840 --> 01:27:53,650
We have a contractor, we hire a contractor
and the contractor is supposed to do the job.

1088
01:27:53,650 --> 01:27:56,340
And, low and behold, the contractor is not
doing the job.

1089
01:27:56,340 --> 01:28:01,720
So we could take a step back and say whack
them on the head, you are not doing the job.

1090
01:28:01,720 --> 01:28:05,780
Or, you can go in and say we have got to get
this job done.

1091
01:28:05,780 --> 01:28:09,280
We are going to go and we are going to send
folks over there that are technical folks

1092
01:28:09,280 --> 01:28:15,280
that will help your guys work these problems
and work the issues and work the integration

1093
01:28:15,280 --> 01:28:15,940
and get this thing done.

1094
01:28:15,940 --> 01:28:20,630
And so, that is what we did.

1095
01:28:20,630 --> 01:28:22,290
That is kind of a typical schedule.

1096
01:28:22,290 --> 01:28:26,210
We have a Comprehensive Acceptance Test.

1097
01:28:26,210 --> 01:28:29,110
That is just a functional test going through
all of the paces.

1098
01:28:29,110 --> 01:28:36,110
EMI is your kind of electrical susceptibility
to noise.

1099
01:28:37,320 --> 01:28:44,320
When you have a palm pilot or a cell phone
and it is near a computer or near some device

1100
01:28:44,730 --> 01:28:46,610
you hear this chattering.

1101
01:28:46,610 --> 01:28:52,890
That is what that test is all about to look
at interference patterns and look at whether

1102
01:28:52,890 --> 01:28:56,380
you are susceptible to noise.

1103
01:28:56,380 --> 01:28:57,620
We have an end-to-end test.

1104
01:28:57,620 --> 01:28:59,490
That is where we get a compatibility van.

1105
01:28:59,490 --> 01:29:06,220
And we make sure that we can communicate with
the deep space network dishes in Goldstone

1106
01:29:06,220 --> 01:29:09,270
and Madrid and Canberra.

1107
01:29:09,270 --> 01:29:14,900
That is our pointing at control systems polarity
test.

1108
01:29:14,900 --> 01:29:19,840
Did we mount the gyro correctly or is it upside
down?

1109
01:29:19,840 --> 01:29:22,570
Did we mount the reaction wheel correctly?

1110
01:29:22,570 --> 01:29:26,220
Do I have the spin vector pointed this way
or pointed that way?

1111
01:29:26,220 --> 01:29:31,740
You think that is pretty simple but, in fact,
on the box it doesn't say arrow pointing up.

1112
01:29:31,740 --> 01:29:35,270
You have to actually test it out.

1113
01:29:35,270 --> 01:29:38,860
And NASA has screwed it up before.

1114
01:29:38,860 --> 01:29:41,880
We do an acoustic test and then a pyroshock
test.

1115
01:29:41,880 --> 01:29:48,880
Acoustic is you blast it with acoustic noise
and the noise couples and creates vibrations,

1116
01:29:48,920 --> 01:29:54,170
especially you are worried about thin films
and large surface areas that are exposed to

1117
01:29:54,170 --> 01:29:56,820
the noise pattern, the wave front.

1118
01:29:56,820 --> 01:30:00,840
So we painted the whole spacecraft with a
huge woofer.

1119
01:30:00,840 --> 01:30:04,240
I mean it was enormous.

1120
01:30:04,240 --> 01:30:10,350
Just to see the vibration and what would happen
to make sure that it was OK.

1121
01:30:10,350 --> 01:30:14,870
And we have the solar ray full motion test
and the low gain antenna release test.

1122
01:30:14,870 --> 01:30:20,880
We have mechanisms which are typically things
that fail a lot or don't operate the way you

1123
01:30:20,880 --> 01:30:22,550
thought.

1124
01:30:22,550 --> 01:30:27,370
We want to test those hopefully in the environment
that they would see in orbit.

1125
01:30:27,370 --> 01:30:33,730
That means if it is cold, if it is exposed
to a plasma we want to try and duplicate that

1126
01:30:33,730 --> 01:30:35,590
on the ground.

1127
01:30:35,590 --> 01:30:37,460
Typically, that is what we do with mechanisms.

1128
01:30:37,460 --> 01:30:37,710
Yeah.

1129
01:30:37,550 --> 01:30:44,550
I was wondering if you had like a separate
satellite that was forecasting and they kind

1130
01:30:45,500 --> 01:30:50,910
of knew that [NOISE OBSCURES].

1131
01:30:50,910 --> 01:30:53,070
Good question.

1132
01:30:53,070 --> 01:30:57,809
Typically, in the old days, when we had a
lot of money, we would build what is called

1133
01:30:57,809 --> 01:31:03,990
a qualification article which is basically
a test article for the whole thing.

1134
01:31:03,990 --> 01:31:08,450
And the qualification article would match
one for one the flight unit.

1135
01:31:08,450 --> 01:31:12,300
And we would test the heck out of that qualification
article.

1136
01:31:12,300 --> 01:31:15,860
Nowadays, with money problems, typically we
don't do that.

1137
01:31:15,860 --> 01:31:21,690
For selected components where we are worried
about the design, we will develop a qualification

1138
01:31:21,690 --> 01:31:23,890
article at the element level.

1139
01:31:23,890 --> 01:31:30,360
But typically we don't do it with whole spacecraft,
not anymore.

1140
01:31:30,360 --> 01:31:35,190
Although, the one exception to that is the
structural test article.

1141
01:31:35,190 --> 01:31:42,190
Usually spacecraft do build a structural test
article that does look like the final flight

1142
01:31:42,190 --> 01:31:44,260
design from the overall structure.

1143
01:31:44,260 --> 01:31:50,610
And you get your mode shapes and your frequencies
when you ring it and see how it performs.

1144
01:31:50,610 --> 01:31:53,780
And you fold that back into your analysis.

1145
01:31:53,780 --> 01:32:00,780
But that is probably the only case where you
build a full test article for structural purposes.

1146
01:32:00,800 --> 01:32:03,140
It would be nice if we could do that.

1147
01:32:03,140 --> 01:32:08,820
The DOD does that when they have a production
of a thousand units, but NASA nowadays cannot

1148
01:32:08,820 --> 01:32:13,450
afford to build a whole complex ground test
article.

1149
01:32:13,450 --> 01:32:17,050
It would be nice but sometimes we just cannot
do it.

1150
01:32:17,050 --> 01:32:24,050
We will do it on a selected element level.

1151
01:32:25,050 --> 01:32:27,630
Hardly ever testing to failure.

1152
01:32:27,630 --> 01:32:34,210
We talked about that with the Shuttle because
JR Thompson was pointing out, like with the

1153
01:32:34,210 --> 01:32:38,670
main engines, testing to failure was really
critical for success.

1154
01:32:38,670 --> 01:32:44,650
But, remember, that is a very different operating
situation than a satellite where normally

1155
01:32:44,650 --> 01:32:50,690
if the satellite can survive launch and the
vibration, and the vibration is tested, the

1156
01:32:50,690 --> 01:32:57,690
structural, you know, if that survives then
the operating environment is a lot more benign.

1157
01:32:58,170 --> 01:33:04,980
Now, what do, though, is we compensate for
not testing to failure by testing with two

1158
01:33:04,980 --> 01:33:09,900
our expected flight environment plus margin.

1159
01:33:09,900 --> 01:33:15,400
Analytically, or based on previous data, we
determine what the environment is going to

1160
01:33:15,400 --> 01:33:15,720
be.

1161
01:33:15,720 --> 01:33:19,550
And we will add margin to that and we will
test to those margins.

1162
01:33:19,550 --> 01:33:23,330
Most times we do pretty well.

1163
01:33:23,330 --> 01:33:28,820
Sometimes we don't, but that is probably few
and far between.

1164
01:33:28,820 --> 01:33:34,220
And we have learned, after 40 years, of how
to apply margin to our best analysis or our

1165
01:33:34,220 --> 01:33:40,360
best tools that define what the environment
is going to be.

1166
01:33:40,360 --> 01:33:47,360
So that kind of shows you starting in October
'87, ending April '98, that was the plan.

1167
01:33:49,630 --> 01:33:55,770
We actually took about nine months more than
what you see there because of all the problems

1168
01:33:55,770 --> 01:34:00,650
that we had.

1169
01:34:00,650 --> 01:34:06,870
A key point is when you are pressed for time
do not cut corners.

1170
01:34:06,870 --> 01:34:10,870
We did review all the testing and we did not
delete any testing that we considered was

1171
01:34:10,870 --> 01:34:12,340
mandatory.

1172
01:34:12,340 --> 01:34:17,840
And, in fact, we added systems testing to
verify that we had total system performance

1173
01:34:17,840 --> 01:34:20,150
that we knew what this thing was going to
do.

1174
01:34:20,150 --> 01:34:27,150
We also added some end-to-end testing in thermal
vac and added much more end-to-end testing

1175
01:34:28,860 --> 01:34:31,460
with the control center that will eventually
operate.

1176
01:34:31,460 --> 01:34:36,880
A lot of times you have, in the integration
and test time, a different set of engineers

1177
01:34:36,880 --> 01:34:41,050
testing this than will actually operate it
in flight.

1178
01:34:41,050 --> 01:34:42,420
Probably not a good idea.

1179
01:34:42,420 --> 01:34:48,990
What you really want is to get your operators
in flight operating and testing early enough

1180
01:34:48,990 --> 01:34:55,460
that they can go through all of the gyrations
of the testing environment and all of the

1181
01:34:55,460 --> 01:35:00,500
idiosyncrasies of the hardware before flight
so that they are trained on the hardware and

1182
01:35:00,500 --> 01:35:03,920
they know how the hardware performs.

1183
01:35:03,920 --> 01:35:10,740
And so, if you can, you want to try and get
the operators to do the testing prior to launch.

1184
01:35:10,740 --> 01:35:16,969
And a lot of times that isn't the case, unfortunately.

1185
01:35:16,969 --> 01:35:17,320
Lesson learned.

1186
01:35:17,320 --> 01:35:23,670
Try to keep one integrated database along
that theme of the Control Center for testing

1187
01:35:23,670 --> 01:35:29,110
and operations because what you don't want
to do is to have a database for testing that

1188
01:35:29,110 --> 01:35:33,900
then you discard and you create a separate
database for operations.

1189
01:35:33,900 --> 01:35:39,900
It is much better to have one database so
that you know what the parameters are.

1190
01:35:39,900 --> 01:35:43,590
And, once you have verified them in test,
they are the same parameters that you are

1191
01:35:43,590 --> 01:35:46,910
using in flight.

1192
01:35:46,910 --> 01:35:53,910
Also, to define an explicit test and integration
lead, review the approach, encourage end-to-end

1193
01:35:55,080 --> 01:35:59,900
testing participations of the operations group
early and often and, if you can, get the operations

1194
01:35:59,900 --> 01:36:06,780
group at the Control Center to run the tests.

1195
01:36:06,780 --> 01:36:11,610
And give adequate time for box level testing
and data system integrated testing.

1196
01:36:11,610 --> 01:36:16,510
A lot of times what will happen is you're
running late on schedule and at the box level

1197
01:36:16,510 --> 01:36:18,300
I have a multiplexer.

1198
01:36:18,300 --> 01:36:23,690
And I had scheduled, at the box level, probably
300 hours worth of testing.

1199
01:36:23,690 --> 01:36:25,070
Well, you know what, I am running late.

1200
01:36:25,070 --> 01:36:28,120
They are wanting me at the spacecraft level.

1201
01:36:28,120 --> 01:36:29,540
Well, let me jip it up now.

1202
01:36:29,540 --> 01:36:33,030
It has only had 50 hours but now I am going
to the spacecraft.

1203
01:36:33,030 --> 01:36:39,500
Low and behold, now what you have just done
is you have moved the problem further on downstream

1204
01:36:39,500 --> 01:36:42,840
when it is much more expensive and it costs
you a lot more money.

1205
01:36:42,840 --> 01:36:47,100
When I have a problem in integrated testing,
guess what?

1206
01:36:47,100 --> 01:36:52,240
The whole spacecraft stops until I fix this
box.

1207
01:36:52,240 --> 01:36:57,309
If you can, try and do it so that you have
got enough margin that you can test at the

1208
01:36:57,309 --> 01:37:04,309
small box level in parallel with all of the
other boxes before you get to integrated testing.

1209
01:37:11,940 --> 01:37:12,190
Management.

1210
01:37:12,130 --> 01:37:14,630
There were plenty of challenges in the management.

1211
01:37:14,630 --> 01:37:18,770
And a term used is unknown unknowns.

1212
01:37:18,770 --> 01:37:23,980
We didn't know at the time that money was
going to be a problem with program restructuring.

1213
01:37:23,980 --> 01:37:26,800
You don't know that you are going to have
an integration delay.

1214
01:37:26,800 --> 01:37:30,840
There are a lot of things that you really
don't know.

1215
01:37:30,840 --> 01:37:34,040
But, nonetheless, you have to expect for and
you have to plan for.

1216
01:37:34,040 --> 01:37:38,830
That is why, at the beginning of a project,
you create what is called reserve resources.

1217
01:37:38,830 --> 01:37:45,830
In terms of cost, depending on the nature
of the complexity, the technology push, you

1218
01:37:46,210 --> 01:37:51,420
may have 20% to 30% of cost held in reserve.

1219
01:37:51,420 --> 01:37:55,280
Not applied anywhere because you don't know
where the problems are going to occur.

1220
01:37:55,280 --> 01:38:01,990
And you try, as a project manager, to hold
onto that by tooth and nail and not release

1221
01:38:01,990 --> 01:38:08,990
it if you can at all and only grudgingly allow
reserves to be used.

1222
01:38:13,820 --> 01:38:18,610
Approach to success in that kind of environment
is experience, getting top management that

1223
01:38:18,610 --> 01:38:23,260
has background and experience, working closely
with the science community.

1224
01:38:23,260 --> 01:38:25,010
Again, focusing on teamwork.

1225
01:38:25,010 --> 01:38:28,780
You will see that as a recurring theme.

1226
01:38:28,780 --> 01:38:33,570
Hold enough reserves so that when you are
scoping out and you've got a lot of unknowns

1227
01:38:33,570 --> 01:38:40,570
that you have enough money and time to do
that.

1228
01:38:41,170 --> 01:38:48,040
Set it as high priority for the company or
the organization that you are working for

1229
01:38:48,040 --> 01:38:53,740
and set the schedule early and balance the
need for maintaining schedule with the need

1230
01:38:53,740 --> 01:39:00,740
to slow down and understand what your problems
are rather than racing to the finish line.

1231
01:39:05,320 --> 01:39:08,250
Again, these are some of the good lessons
learned.

1232
01:39:08,250 --> 01:39:14,219
In fact, I just covered that one.

1233
01:39:14,219 --> 01:39:21,219
This is what it ended up being, the AXAF Schedule
starting around calendar year '92 with our

1234
01:39:22,300 --> 01:39:22,860
SRR.

1235
01:39:22,860 --> 01:39:27,840
There is our PDR and there is our CDR.

1236
01:39:27,840 --> 01:39:31,940
And the launch is even off the chart.

1237
01:39:31,940 --> 01:39:37,430
But that is typically the kind of things that
we go through, including in parallel your

1238
01:39:37,430 --> 01:39:44,430
Control Center development back down here.

1239
01:39:46,800 --> 01:39:49,490
There is a mirror.

1240
01:39:49,490 --> 01:39:54,830
All of this will be posted.

1241
01:39:54,830 --> 01:39:59,000
I mean these are really valuable lessons.

1242
01:39:59,000 --> 01:40:06,000
In fact, any of you who eventually go into
systems engineering and project management

1243
01:40:06,040 --> 01:40:08,070
take some of these lessons learned with you.

1244
01:40:08,070 --> 01:40:08,990
Print them out and review them periodically.

1245
01:40:08,990 --> 01:40:13,440
And remember them.

1246
01:40:13,440 --> 01:40:14,740
They are lessons of hard knocks.

1247
01:40:14,740 --> 01:40:21,740
What I am doing is now is I am now the project
manager for a project or a mission called

1248
01:40:21,809 --> 01:40:28,440
RLEP 2, which is Robotic Lunar Exploration
Program.

1249
01:40:28,440 --> 01:40:33,980
And that mission will be the first mission
that NASA has, in a long time, to land on

1250
01:40:33,980 --> 01:40:34,340
the Moon.

1251
01:40:34,340 --> 01:40:37,360
We are going to land the Lander.

1252
01:40:37,360 --> 01:40:44,360
And we are going to have some type of mobility
device that will either drive into a crater

1253
01:40:45,940 --> 01:40:52,940
or hop into a crater or crawl into a crater
or walk into a crater and look for lunar ice

1254
01:40:53,590 --> 01:40:57,910
that we think might be there at the South
Pole.

1255
01:40:57,910 --> 01:41:04,910
Now, this is a great example of how things
are done.

1256
01:41:04,920 --> 01:41:11,920
We are given a couple of requirements to say
we want to verify our precision landing capability

1257
01:41:13,570 --> 01:41:18,969
in an unmanned sense, and we are going to
use that technique and those algorithms for

1258
01:41:18,969 --> 01:41:22,559
the future human lander.

1259
01:41:22,559 --> 01:41:26,460
And we are also going to need you to go look
at the ice.

1260
01:41:26,460 --> 01:41:31,460
Characterize it and see whether or not ice
is there.

1261
01:41:31,460 --> 01:41:33,130
Now, why is ice so important?

1262
01:41:33,130 --> 01:41:37,500
Ice is important because of the oxygen that
you can get from the ice.

1263
01:41:37,500 --> 01:41:44,500
And the oxygen is not so much to breathe but
it is for fuel or for oxidizer for propulsion

1264
01:41:46,800 --> 01:41:47,740
systems.

1265
01:41:47,740 --> 01:41:52,090
Instead of getting it at the earth's gravity,
well, you get it at the gravity well of the

1266
01:41:52,090 --> 01:41:53,030
Moon.

1267
01:41:53,030 --> 01:41:55,880
That is our challenge.

1268
01:41:55,880 --> 01:42:02,880
Now, when they asked that, NASA didn't exactly
know what it would cost or what the cost profile

1269
01:42:06,170 --> 01:42:07,170
would be.

1270
01:42:07,170 --> 01:42:11,090
They originally designed it for a $400 million
mission.

1271
01:42:11,090 --> 01:42:18,090
They said, well, why don't you look at a $750
million solution?

1272
01:42:19,580 --> 01:42:24,940
They don't know how many objectives we can
meet.

1273
01:42:24,940 --> 01:42:31,559
This RLEP is supposed to be robotic lunar
exploration.

1274
01:42:31,559 --> 01:42:38,490
It is really a precursor to the human missions,
so they are not even sure how to use this

1275
01:42:38,490 --> 01:42:42,160
program to help bring humans there.

1276
01:42:42,160 --> 01:42:44,710
And so, this is typical.

1277
01:42:44,710 --> 01:42:50,780
NASA doesn't exactly know what it wants to
do, but it kind of puts out feelers to say

1278
01:42:50,780 --> 01:42:51,340
try this.

1279
01:42:51,340 --> 01:42:58,340
It says go start with this, go touch the lunar
surface, characterize precision landing and

1280
01:42:59,480 --> 01:43:01,590
go see if there is ice there.

1281
01:43:01,590 --> 01:43:05,320
Well, go see if there is ice there.

1282
01:43:05,320 --> 01:43:12,320
I can do that with one hop into the crater,
one sample and hopefully, if the ice is there

1283
01:43:13,360 --> 01:43:14,469
I can find it.

1284
01:43:14,469 --> 01:43:21,469
Or, on the other extreme, I can go with a
Rover, spend a year in the crater, take a

1285
01:43:22,219 --> 01:43:25,059
thousand measurements and characterize the
ice.

1286
01:43:25,059 --> 01:43:30,500
Obviously, one cost a lot more than the other.

1287
01:43:30,500 --> 01:43:33,460
So how in the world do you answer that question?

1288
01:43:33,460 --> 01:43:37,580
Which one should you do and whether it should
be a mix?

1289
01:43:37,580 --> 01:43:42,260
Those are the very things facing the project
that I am working on now.

1290
01:43:42,260 --> 01:43:49,260
Not only that, one of the things is we are
trying to get prepared for a human mission

1291
01:43:50,510 --> 01:43:55,170
and we want to reduce the overall cost and
reduce the risk.

1292
01:43:55,170 --> 01:44:02,170
We would like to bring risk forward from the
manned lunar mission into the RLEP program

1293
01:44:03,360 --> 01:44:06,610
and retire it in the robotics program.

1294
01:44:06,610 --> 01:44:12,490
What that means is if I have a technology
challenge for a cryogenic engine, that means

1295
01:44:12,490 --> 01:44:19,490
a liquid oxygen, liquid hydrogen engine for
the lunar descent, I want to use that same

1296
01:44:19,969 --> 01:44:25,010
engine, if I can, on this mission to work
out the kinks.

1297
01:44:25,010 --> 01:44:29,820
But how much is that worth to NASA?

1298
01:44:29,820 --> 01:44:36,820
If that cost an extra $100 million for RLEP
is it worth it?

1299
01:44:38,800 --> 01:44:41,530
There is no set answer.

1300
01:44:41,530 --> 01:44:44,600
And so, what we are doing right now is what
is called a pre-phase A.

1301
01:44:44,600 --> 01:44:49,700
Much like I showed you on Chandra where you
had that initial design and a final design,

1302
01:44:49,700 --> 01:44:53,290
we propose to headquarters with one design.

1303
01:44:53,290 --> 01:44:54,809
It happened to have a Rover.

1304
01:44:54,809 --> 01:44:56,010
It was nuclear powered.

1305
01:44:56,010 --> 01:44:59,330
We went into the crater.

1306
01:44:59,330 --> 01:45:00,850
And we stayed there for quite a while.

1307
01:45:00,850 --> 01:45:05,570
And we definitely characterized what was there.

1308
01:45:05,570 --> 01:45:07,920
But it was expensive.

1309
01:45:07,920 --> 01:45:08,700
Is that the right answer?

1310
01:45:08,700 --> 01:45:11,070
We don't know.

1311
01:45:11,070 --> 01:45:17,070
We are right now going through a pre-phase
A that we are looking at other options.

1312
01:45:17,070 --> 01:45:20,610
We are looking at kind of three classes of
sizes.

1313
01:45:20,610 --> 01:45:23,420
Different solutions to get into the crater.

1314
01:45:23,420 --> 01:45:26,320
Different solutions on the size of the lander.

1315
01:45:26,320 --> 01:45:29,510
Its extensibility to the human mission.

1316
01:45:29,510 --> 01:45:36,510
Like, for instance, right now we use Russian
progress vehicles to resupply Space Station.

1317
01:45:36,780 --> 01:45:43,780
We hope to design a robotic lander that would
do the same thing during human missions.

1318
01:45:43,920 --> 01:45:50,920
It is not man rated, it won't fly men but
it can fly supplies to the Moon with one design.

1319
01:45:52,570 --> 01:45:59,090
But that cost money because now I am not optimizing
design for a point solution mission.

1320
01:45:59,090 --> 01:46:03,610
So during this timeframe there are a lot of
unknown questions.

1321
01:46:03,610 --> 01:46:06,550
And the answers are not straightforward.

1322
01:46:06,550 --> 01:46:12,740
So what we are doing is we are giving a series
of options and rationale and capabilities

1323
01:46:12,740 --> 01:46:14,780
for those options to headquarters.

1324
01:46:14,780 --> 01:46:20,230
And we will make a recommendation as to what
we think is the best answer for NASA to go

1325
01:46:20,230 --> 01:46:23,580
forward with this design and here are the
reasons.

1326
01:46:23,580 --> 01:46:29,710
But it could very well be that they choose
something different because there is no definitive

1327
01:46:29,710 --> 01:46:35,420
solution to this problem or this challenge,
if you will.

1328
01:46:35,420 --> 01:46:36,809
So it is very challenging.

1329
01:46:36,809 --> 01:46:41,620
It is going to look probably a lot different
now than it will when we actually launch it

1330
01:46:41,620 --> 01:46:47,240
in 2010 or 2011, but it is something that
we face now.

1331
01:46:47,240 --> 01:46:54,240
And it is more defined by how much money you
can use versus what the requirements are.

1332
01:47:00,430 --> 01:47:06,340
Sometimes the requirements do set pretty much
the basic tenets of the mission, but other

1333
01:47:06,340 --> 01:47:09,260
times it is driven by cost.

1334
01:47:09,260 --> 01:47:15,809
And so, right now we are in the middle of
working that interesting and challenge problem

1335
01:47:15,809 --> 01:47:22,370
for headquarters to develop what we think
that mission should look like.

1336
01:47:22,370 --> 01:47:25,590
And, as you can envision, you don't really
have requirements.

1337
01:47:25,590 --> 01:47:27,719
You have a few requirements.

1338
01:47:27,719 --> 01:47:33,700
You have a desirability to reduce the overall
cost and reduce the overall risk of a human

1339
01:47:33,700 --> 01:47:35,860
mission.

1340
01:47:35,860 --> 01:47:38,680
But that desirability comes with a cost.

1341
01:47:38,680 --> 01:47:44,670
The more extensible you get to the human mission,
yes, you can make a big lander that gives

1342
01:47:44,670 --> 01:47:48,840
you 2,000 kilograms of payload, but it is
going to cost you more.

1343
01:47:48,840 --> 01:47:55,840
I can make 1,000 kilograms of payload or 500
kilograms of payload and get the definition

1344
01:47:56,200 --> 01:47:57,660
of what is in the ice.

1345
01:47:57,660 --> 01:48:04,080
But then later on I will have to design a
new lander for getting other things accomplished

1346
01:48:04,080 --> 01:48:05,980
that I want to get to on the Moon.

1347
01:48:05,980 --> 01:48:09,510
And is that the right answer?

1348
01:48:09,510 --> 01:48:15,070
You can tell that there are a lot of challenges
with that?

1349
01:48:15,070 --> 01:48:15,660
Any questions?

1350
01:48:15,660 --> 01:48:20,760
We talked about the cost, performance and
schedule triangle.

1351
01:48:20,760 --> 01:48:27,760
Do you have a sense, inside NASA, of how much
they are pushing schedule at this point/ Where

1352
01:48:29,690 --> 01:48:33,740
is your flexibility?

1353
01:48:33,740 --> 01:48:39,740
In their solicitation to the centers, they
allowed schedule flexibility.

1354
01:48:39,740 --> 01:48:41,330
They allowed cost flexibility.

1355
01:48:41,330 --> 01:48:48,330
Other programs I will say are generally more
bounded than this one.

1356
01:48:49,070 --> 01:48:56,070
This one is a matter of NASA not knowing exactly
what the reason and what the purpose of the

1357
01:48:56,760 --> 01:48:58,570
program is for.

1358
01:48:58,570 --> 01:49:05,160
You've got this general idea of going back
to the Moon, using robots first to prepare

1359
01:49:05,160 --> 01:49:10,750
for humans, but exactly what does that mean
and exactly how do you prepare for humans

1360
01:49:10,750 --> 01:49:14,420
and how much is it going to cost and when
is it going to launch and how many missions

1361
01:49:14,420 --> 01:49:16,190
are you going to have?

1362
01:49:16,190 --> 01:49:17,610
They are all undefined.

1363
01:49:17,610 --> 01:49:23,920
Now, what we would do is we have already gone
to the program that will fund the human missions

1364
01:49:23,920 --> 01:49:29,030
to say what do you guys plan to do and what
do you want to do when you get there?

1365
01:49:29,030 --> 01:49:33,070
So we can take their mission design and say
how can we help?

1366
01:49:33,070 --> 01:49:34,190
We can help here.

1367
01:49:34,190 --> 01:49:35,550
We can help here.

1368
01:49:35,550 --> 01:49:38,559
We can pull this technology forward and fly
it.

1369
01:49:38,559 --> 01:49:42,110
The problem there is that they haven't thought
that far ahead.

1370
01:49:42,110 --> 01:49:45,820
They don't know exactly what they are going
to do.

1371
01:49:45,820 --> 01:49:51,410
And a lot of that is, is there ice there or
not?

1372
01:49:51,410 --> 01:49:54,050
If there is ice there, we will want to process
it.

1373
01:49:54,050 --> 01:49:58,690
We will want to extract oxygen from it.

1374
01:49:58,690 --> 01:50:02,780
As part of our solution, we do know that we
have to answer that question.

1375
01:50:02,780 --> 01:50:07,809
We also do know that we do have to demonstrate
precision landing.

1376
01:50:07,809 --> 01:50:13,990
But, above that, they have given us a target
date of 2010 to 2011.

1377
01:50:13,990 --> 01:50:17,690
But they said schedule is not fixed.

1378
01:50:17,690 --> 01:50:22,880
They have given us a cost generally between
$400 and $750 million.

1379
01:50:22,880 --> 01:50:28,730
And, by the way, if you can leverage areas
of the budget to help your mission, do that,

1380
01:50:28,730 --> 01:50:30,190
in particular technology.

1381
01:50:30,190 --> 01:50:32,990
There is a separate technology budget.

1382
01:50:32,990 --> 01:50:39,170
If I can get technology to pay for a new technology
development at no cost to the program then

1383
01:50:39,170 --> 01:50:42,790
I will do that.

1384
01:50:42,790 --> 01:50:49,790
And, again, if we come in and say we have
$1 billion but it buys you $3 billion when

1385
01:50:52,110 --> 01:50:56,980
the crew is ready to come, we think that is
worth the investment.

1386
01:50:56,980 --> 01:51:02,760
And then headquarters has to scratch their
head and figure out whether it is really worth

1387
01:51:02,760 --> 01:51:09,650
minimizing the long-term cost versus the yearly
constraint that they are given by Congress

1388
01:51:09,650 --> 01:51:14,960
and the pressures of Shuttle and the pressures
of Stations on the overall cost of the program

1389
01:51:14,960 --> 01:51:16,469
to NASA.

1390
01:51:16,469 --> 01:51:20,070
It is real challenging.

1391
01:51:20,070 --> 01:51:21,770
It is a lot of fun.

1392
01:51:21,770 --> 01:51:23,430
We are going to have a blast.

1393
01:51:23,430 --> 01:51:29,090
The next one is going back to the Moon, and
you will probably hear more about it in the

1394
01:51:29,090 --> 01:51:29,880
next couple of years.

1395
01:51:29,880 --> 01:51:31,969
OK.

1396
01:51:31,969 --> 01:51:36,150
Thank you.

1397
01:51:36,150 --> 01:51:38,250
[APPLAUSE]

1398
01:51:38,250 --> 01:51:42,230
This was really the last of the lectures on
systems engineering per se.

1399
01:51:42,230 --> 01:51:45,830
Thursday is the last external lecture.

1400
01:51:45,830 --> 01:51:50,990
Gordon Fullerton will be talking about test
flying the Shuttle.

1401
01:51:50,990 --> 01:51:57,990
And hopefully by then I will have the schedule
for the presentations next Tuesday.