Preflight Interview: Dominick Gorie
we get into the specifics of this flight, I want you to tell me
a little bit about yourself. Why did you want to become an astronaut?
memories I have are of wanting to fly. I always knew I wanted
to do that. My natural father was a Pilot in the Air Force, and
I remember sitting on the hood of a Buick at the airport watching
big bombers fly over our heads and that was the most exciting
thing I could imagine. I got into the Naval Academy and went into
flight school and started flying F-18s and had a wonderful time.
I remember also as a young boy watching the earliest Apollo missions
and watching guys walk on the moon. That was a dream of mine but
I couldn't imagine myself being that fortunate. I think once I
became a test Pilot and saw that now the doors were open for me
to apply to be an astronaut, I did that with everything I had.
I think there are hundreds and thousands of people out there that
are just as capable as I am to be an astronaut. But, for whatever
reason, NASA decided to let me come do this and I'm having a great
tell me a little bit about the particular path that got you to
this point. How did you get here?
I flew F-18s
in the Navy and A-7s a little bit before that so I am used to
flying single seat airplanes. I had a great time with each tour
that I had in the Navy, and each one actually got better, I thought.
As a test Pilot, you experiment with different airplanes and different
systems, and NASA likes to see that background in their Pilots,
so they pretty much have that as a requirement. Once you have
that in your resume, you can apply to come to NASA. I had to apply
a couple times before they relented and let me join the Astronaut
Office. I would say that my background is mostly flying single
seat airplanes and then I was a test Pilot.
for me what you'll be doing during this flight. What are your
is in charge of the main engines, the hydraulic systems and the
electrical systems during the ascent and entry phases. Once we
get on orbit, Kevin will put me in charge of the Blue Shift. Once
he, Gerhard and Janet go to sleep, I'll be running the Blue Shift
with Janice Voss and Mamoru. I'll be in charge of the basic shuttle
systems and how the shift is run during those times that we're
awake. When we're on orbit, I'm doing some attitude maneuvers
and orbit adjustment burns as well as helping out the two Mission
Specialists on the payload.
mission will look back at the Earth using radar interferometry
to acquire topographic data. Could you explain for me - what is
I think most
people have a basic understanding of what radar does; it will
send out a wave that will return an image of the ground. On this
flight we have two antennas that are looking at the same radar
return and they look at the phase difference in the return wavelengths.
If you can think of two waves of water returning from the same
source but going to two different points, the wavelength might
hit those two different points at different places. Where one
person standing in the water might receive the top of the wavelength,
or the wave, a person standing two feet behind them might receive
the trough, or the bottom of the wave. When you compare those
two differences in the wavelength, that's called the phase difference,
and the difference is totally due to an altitude difference. So
if you go into the geometric analysis and look at the baseline
distance between the two radar antennas and use the phase difference
between those two returning wavelengths, you can determine the
altitude of the source that you bounce that radar wave off of.
When you can add that to the radar picture, you can build a 3D
image of the terrain that you're mapping.
Shuttle Imaging Radar-C, or SIR-C, and the X-band Synthetic Aperture
Radar, or X-SAR, flew on the shuttle in April and October of 1994.
What are the innovations for SRTM to separate it from the first
couple of Space Radar Lab missions?
and most obvious difference is the huge mast that will be sticking
out 60 meters or 200 feet. That will give us the baseline difference
between the main antenna and the extended antenna and that will
allow us to measure the phase difference or the difference between
the return wavelengths. That's what will give us elevation data.
The previous flights were not getting any elevation data; they
were just mapping the surface in the picture of what they were
tell me about the mast deploy. What happens during that process?
interesting about this 200-foot mast is that it is in this relatively
tiny canister and that it can extend out 200 feet in a unique
and innovative fashion. Most garage door openers use a screw drive
that continuously drives the garage door open and some of them
might use a chain. But the screw drive one is what we have at
home. This is a similar system, although the screw drive doesn't
go continuously in the same direction. It will reverse for each
bay that's extended, and we have 87 bays that make up this 200-foot
mast. As each bay opens up and locks into position, the screw
drive will reverse its direction, and so the mast is uncoupling
all the way out for 200 feet. We've seen a small model of it and
small extensions of it during trips to the Jet Propulsion Lab.
But I think to see it in real time and real life once we get on
orbit is going to be great.
happens if the mast does not fully deploy? Can you do an EVA to
fix the problem?
a couple things that we can do to fix a stuck mast. First, if
the latches don't open on the canisters, Janice and Gerhard are
prepared to go out and do an EVA to manually open those latches
with some special tools. We could also have a motor problem that
prevents the mast from fully extending, and they have these huge
pistol grip tools that are amazing pieces of machinery. Most people,
I think, are familiar with small hand tools or drills or electric
cordless screwdrivers. This thing really puts those to shame,
and it is quite massive. But in zero-g they're easy to handle,
and they would go out with a couple of space batteries and manually
put this power tool on the screw drive, pull the trigger, and
wait for the mast to deploy manually. They would have to take
turns doing that because it would take quite a long time, and
they have spare batteries to swap out as they extend it.
understand that the length of the boom creates its own set of
problems. What is the gravity gradient force, how does the boom
affect it, and what are you doing to counteract it?
gradient force comes into play whenever you have two different
bodies that are connected together in space. Because they're traveling,
in essence, at different speeds around the Earth, there's a force
called the gravity gradient force that will try to pull them apart.
Think of a car going around a corner and the people that are inside
are thrown to the outside of the turn. Those two bodies in space
will line up with the centrifugal force vector or 90 degrees out
from our velocity vector. That means that the antenna and the
orbiter are lined up with each other with the orbiter closer to
the Earth and the antenna pointing away. The force that is driving
that is only a couple of ounces. So we've designed a system using
nitrogen that comes out of a small nozzle at the tip of the antenna
that only emits about a one or two ounce force. That pushes the
mast down when it's trying to achieve its gravity gradient condition
which is pointing straight up, but the cold gas pressure from
the nitrogen gas is pushing down at an equal and opposite force
of two ounces or so to hold it right where we want it. That way
the orbiter's not constantly using reaction control jets to return
it to its desired attitude.
is the fly cast maneuver, and why are you using it?
a fisherman standing out in the middle of the river fly casting
his rod back and forth. That's what would naturally happen to
our mast if we were to disturb it. So I brought a small model
here to show this. We've got this mast sticking out from the space
shuttle. Once a day, because we're at a fairly low altitude, we
have to adjust our orbital altitude. We do that with a couple
of reaction control jets in the aft end of the space shuttle.
If we were to do that without thinking about the ramifications
on the mast, we would pulse on the back end of the orbiter with
the reaction control jets and the mast would deflect backwards
because of its mass and inertia. Once we stop the burn, if we
let it go the mast would swing back and forth. What we have designed
is a maneuver that will minimize the deflections on the mast and
minimize the loads at the tip. If we did this without the fly
cast maneuver, we would have a 35-inch deflection at the mast
tip, and we would approach the mast limit loads at the base. So
we pulse just for a short time - 1/6 of the natural frequency
of the mast - and the mast will deflect back slightly. Right when
it starts springing backwards, we will pulse again and in essence
catch it in its deflected state. We are then burning the reaction
control jets for the duration of the burn that it takes to adjust
our altitude. When we stop the burn, the mast wants to start swinging
back and, if left alone, it would start fly casting again. It
would start twanging back and forth just like that fly fisherman's
rod. As it reaches back to its neutral position, we do one more
pulse at 1/6 the frequency of the mast for that duration and catch
it in its neutral position. That way we take those 30 plus inches
of deflection that we would expect without a fly cast maneuver
and we half it to 15 inches and the mast loads at the tip are
halved as well. What we've done is designed a maneuver that achieves
our end parameters but greatly reduces the risk of damage to the
could be done if you had trouble with the retraction of the mast?
For example, could it be jettisoned if it got stuck?
two things we can do. First of all, we could send Janet and Gerhard
back out there with those power tools that we talked about previously,
and they could hook them up to the drive motors and retract it
manually if it was a motor problem. If it's something else that's
stuck like a bay that we can't get to and we don't have the capability
to EVA out on the mast, then we have a jettison system that will
deploy some pyrotechnics and release the mast from the payload
bay. Then we can do a normal back-away maneuver like we do with
any deployable satellite. Then, in that case, the mast would be
lost, but we would be able to close the payload bay doors and
the surface, this flight has similarities to the Tethered Satellite
System flights because you're deploying a long system out of the
cargo bay. Do you anticipate having any of the concerns similar
to those associated with those flights?
Satellite is a completely different system. I think when you talk
about deploying something on a loose cable out to the distances
they were talking about, you can't really equate that to what
we're doing. What is consistent, though, is that we're trying
to do something that nobody's ever done before. No one has ever
tried a Tethered Satellite deploy, and no one's ever tried to
deploy a rigid structure this far out from a space ship or a spacecraft.
So in that respect, we're both trying something innovative that
has some unknowns to it. You can make some parallels, but I think
that's about it.
the SRL missions, they had specific mapping targets on their surface.
Do you have anything like that on this flight?
is attempting to map all the landmass that we can. We're not turning
the radar on and off just for specific spots over the ground.
What we're doing as we cross a continent or an island or any landmass
is we're turning the radar on and we're leaving it on for the
duration of that land pass and once we get back over the water
then we turn it off. I think our goal is to get a much broader
database on land returns.
mentioned that you turn the radar off when you go over the oceans.
Do you turn it back on, for example, when you go over an island
mass of some sort?
The Jet Propulsion
Laboratory and the SRTM folks have a detailed plan already in
work on when those data takes will start and when they will stop.
They will cover islands when they can get them, as well as the
continents. So we will try to map every land mass that comes up.
is the data being recorded instead of downlinked live?
rate, I think, that we're getting is almost 9 kilobits a second,
and right now we don't have the capability on the shuttle to downlink
data at that high rate. We just don't have the communication equipment
or systems to do that. So we've got some recorders that we use
that record in high data rate on some special tapes. We record
at that data rate and fill them up in about 30 minutes of C radar
data. The X radar data will fill up a tape in about an hour, but
once the flight is complete, we're going to have a huge amount
of data. I think that the number is 8 or 9 terabytes which is
something I can't comprehend. I think somebody told me that if
we stacked CDs with that much data, it would take 15,000 of them
on top of each other to get as much data as we're going to get
on 300 tapes.
getting this massive amount of data. How long is it going to take
to process all this?
I have heard
some other analogies as well. I think NIMA expects to take a year
or two to process all of it. But the analogy I heard was if you
had 144 Pentium computers running twelve hours a day, it's going
to take you 140 days to process all that data.
will we learn about the Earth from the data you do acquire on
this mission, and what kind of applications are there for what
you're going to learn?
NIMA is an
organization that works for the government, and they have some
national security concerns and uses for that data. Along with
that, there are many Earth sciences people that are very interested
in what we will bring back. NIMA and the German DLR folks that
are running X-SAR are going to make that data available for different
scientists and engineers that are interested in many aspects of
Earth life. If somebody is interested in building a dam, they
would want to know what the elevation data would indicate and
where they could build it. Mining engineers would want to know
where they could go exploring and what elevation is going to mean
to them once they go into an interior part of the country. People
that are interested in terrain following for airplane piloting
or air traffic control would like this kind of data. Or for people
that are interested in recreational uses, such as hiking or camping
in the mountains, we can have great maps built for that. I think
the possibilities will unfold to us, but right now the Earth sciences
people are really excited already.
the payload is functioning properly, the crew slips into a pretty
regular routine. Do you think the work will get boring or tiring
for you up there?
I think that
although the work will become regular and routine as far as watching
data takes and swapping out tapes on our recorders, I can't imagine
ever thinking that space flight would get boring or routine. When
you think about the data that we're bringing back and what it
will mean to the scientists and engineers that are looking forward
to receiving it, it is unbelievable. And if that doesn't excite
you enough, just looking out the window can fill your time. We've
got a couple of other small payloads that will keep us busy, like
GPS, the Global Positioning Satellite experiment that we're running.
We've got a couple of things that we're working for NASA. A big
high definition TV, a group of data takes or film takes that we
will make during the flight. So there's plenty to keep us busy,
and I can't imagine we will ever get bored with it all.
of the other payloads is something called EarthKam. What can you
tell me about EarthKam?
is a system that's set up for students in their schools to work
real time with the space shuttle. They can send commands up to
a computer on the flight deck that's running the EarthKam software.
The EarthKam is connected to a digital camera that's located in
the overhead window, and they can command times, latitudes, and
longitudes for when they want their camera to take pictures. They
can program on the ground what they would like to take a picture
of, have it taken on orbit and then downlinked, and they can actually
see what the space view of that terrain is. And they can then
see what scientists and engineers do for Earth effects and Earth
studies from real time work. And it's exciting, I think, for students
all over the country to get involved real time with what a space
shuttle experiment is doing on orbit.
would you characterize the long-term importance to science of
the work that you and your crewmates will be doing on STS-99?
all, when we deploy a rigid structure in space, it will enable
us to learn many things about engineering and building in space.
If we want to build some large structure on a space station or
on a visit to another remote planet, doing this and demonstrating
this capability is very important, I think. The data that we bring
back from the flight will be extremely important to NIMA for its
national security reasons, as well as to all of the Earth sciences
scientists and engineers. I think there are many uses for this
data that we probably don't even know about. Once people can see
that the data's available, they'll come up with many uses for
it that we don't even anticipate.