Transcript of Webcast:
Space Day 2003
January 29, 2003

With Guest Expert:
John F. Muratore

>> Hello, everyone out there and worldwide web land.
My name is Sherri Jurls and I would like to welcome you to the Distance Learning Outpost program here live at the Johnson Space Center in Houston, Texas.
Today we're going to take a look at the Space Day 2003 design challenge number two entitled, "Planetary Explorers."
We're so excited that all of you are joining us today.
Here is the challenge: For you to design and build a working model spacecraft that can fly not only on Earth, but on another planet as well.
It must be designed with characteristics that would allow it to fly on another
planet of your choice, the moon in our solar system and that you have to write and illustrate a story that involves your spacecraft.
You also have the create a timeline of past and future events in flight.
Now, teachers, if you still want your students to be involved in the Space Day
2003 design challenges it's not too late.
You can still sign up today.
All of the teachers who register their students for the design challenges before
the March 3, 2003 deadline, will receive educational incentives for your
classroom.
So teachers and student teams who register and submit your design challenge
solutions by March 3 will receive additional special aviation-related incentives
for your classroom.
Again, your projects are due by March 3 and to help answer some of your questions, we have a very special guest with us here today.
His name is John Muratore, but before we meet him I want to talk a little bit
about him so you guys know his background and the kinds of questions that you can ask him today.
He holds an undergraduate degree in engineering from Yale University.
And he also has a masters degree in computer systems from the University of
Houston.
He's also working on his doctorate right now in electrical engineering.
For four years he was an officer in the United States Air Force and he began his career at NASA in communications in the Mission Control Center.
He went on to become a flight director for us here at NASA and served as a flight director for four different space shuttle flights.
He was then put in charge of rebuilding an upgrading our Mission Control systems room, which is really awesome.
If any of you ever have a chance you come visit us at Johnson Space Center and check it out.
Well, for the last seven years John has been the principal architect of NASA's X-38 program which was responsible for building a prototype spacecraft to be used as an emergency return vehicle for our astronauts from the International Space Station back to Earth.
Much of his work on this program has been an opportunity to fly and conduct flight testing on this X-38 and also working with lots of military aircraft.
And he's now working on a brand new project in biotech experiments to fly on board the space station but we'll call upon his expertise of the X-38 aircraft.
Welcome, John.
We're happy to have you with us today.
>> It is great to be here.
>> Will you take a moment and briefly tell us about your X-38 experience, a little overview?
>> Sure.
What we had to do in the X-38 program was to find a way to be able to bring
astronauts back from the space station in case of an emergency.
Damage to the space station or someone getting sick on the space station and the shuttle wasn't there and having to bring them back to earth.
We developed a spacecraft system that would do that job.
It had to fly three different kinds of spacecraft.
It had to be a space vehicle flying around in orbit.
Then it had to fly like the shuttle flying into the heat of the atmosphere and
land like an airplane so it was really three kinds of spacecraft in one.
If you want, we have a little video section of that that we could show everybody and see the three different ways it works.
That might be a hint to people.
Because in this exercise they've got to figure out how to make an aircraft fly in
two different kinds of planets.
>> Is this the X-38 we'll be taking a look at?
Okay.
Great.
As this starts rolling we'll have you talk about what is going on in this flight
test.
>> Okay.
This is the space station when it was -- And this is -- you'll see a scenario or
an example of how it would fly away from the space station.
First operating like a spacecraft in earth orbit and then it is going to fire some
rocket engines that slow it down and bring it in the atmosphere and fly under a
giant parachute.
Here you see the crew getting into the spacecraft.
It is one of the most important things you have to think about in spacecraft
design.
If you'll have people in the spacecraft, how are they going to work in the
spacecraft.
How will they be seated to protect them and touch the controls.
How will they be able to look out the windows, issues like that.
So here it is getting ready to leave the space station.
>> John, some of the students, based on this portion that we just watched, may
have thought of a question or two that they've come up with and we're going to go to the chat room and see if any of the students have submitted a question.
We want to remind everybody that at any time during our program today we encourage you to log into the chat room and ask your questions for John.
He's an expert.
That is what he's here for to help you through this process of creating your
design challenge.
And I see that we have quite a few teams already joined together logging onto our chat room.
Smart lab in Cincinnati, Ohio, Smart lab must be their team lab.
They're a group of students and adults in a program that helps people with
learning disabilities find out more about science and technology and computers.
They've got 40 people working on the Space Day projects.
How exciting.
>From artist to model builders and researchers and they're watching today.
If you guys have a question, please pop on and ask us a question.
Now, team ICARUS from Iowa, they're doing a project with a solar sail on their aircraft and they want to know how long would it take a solar sail to get to Mars and how big would it have to be to get people there.
>> That's an interesting question.
We've spent a lot of time using how we could use solar sail propulsion to get to Mars.
I'm afraid it's a long time depending on the size of the sail it could be at least
a year in terms of transit, in terms of the time to get to Mars and it would have
to be several football field size.
Even though there are lots of particles hitting the sail they move very slowly.
>> As we're continuing on watching this video clip and talk about the next
section, you guys be thinking about the questions that you have about your
projects and pop those into the chat room.
Let's continue on with the video, John.
>> Okay.
Great.
Here is a beautiful Edwards Air Force Base in California.
Those are the famous Joshua trees in the desert.
This is the morning of a flight test.
One of the things about the rescue vehicle it doesn't have any engines on it to
fly in the atmosphere so we have to take it up in the air to test it.
We do that by dropping it from a military aircraft called a B-52 bomber.
It's a very old aircraft.
It is interesting.
It's older than I am.
I always got nervous getting on the airplane because it's old.
It works very well for NASA.
This is a picture of me up in the bomber where we've got a little computer screen, a little laptop that enables us to command and control the vehicle.
Here we are taxiing out.
And there is the X-38, the white vehicle that's under the right wing or what they call the star board wing.
Here are the chase airplanes and photo airplanes.
Here is a picture and shot inside the helicopter.
Because of all the different kinds of ways we fly in the X-38 we have to have
different airplanes because it flies at different speeds.
We have to have different airplanes capable of flying at different speeds to get
photos of it.
This is where we're taking off.
About the B-52 this old airplane that makes tons of smoke when it takes off and it makes lots of noise.
The lift is being generated by the huge wings on the bottom.
Something you would need flying with a heavyweight in the earth's atmosphere but something flying in Mars atmosphere you need it light.
Here is the control room and out on the desert floor waiting for the flight to
start.
We put -- we test all the systems on the airplane before we drop it.
Those are the flaps that enable us to control how the nose goes up and down on the vehicle.
You see the -- we're 45,000 feet in the air.
About nine miles in the air.
There we go flying free.
The camera from on side of the vehicle looking up at the bomber as we fly away.
You see us flying like an airplane flies.
>> It looks so small.
>> The bomber is so big.
It's actually 30 feet long.
It's the size of a segment of a football field.
Here we'll put out a parachute.
This may look small but it is 100 feet in diameter when it gets fully inflated.
This is just the parachute we use the slow the vehicle down and then we pull out the really big chute.
It is a square chute called a parafoil.
It acts like an airplane wing.
We put it up in the air and inflate it.
When it gets fully inflated.
It is going out in sections and being deployed in sections in different colors.
When it's fully out it is 50% bigger than the wing of a Boeing 747 or a big -- the biggest of the big commercial airliners.
So we get the advantage inside a little spacecraft of having a wing as big as that of a big jetliner.
>> Didn't you say it's the world's largest parafoil?
>> We have the record by several hundred square feet.
Those are big enough that a six-foot person can stand in it and not touch the top.
>> Those sails are huge.
>> They are and they fill up full of air and are stiff and ridgeed so we can
support the vehicle.
The vehicle looks tiny but it is actually 18,000 pounds or about nine tons.
It is a heavy vehicle.
We were going 600 miles-per-hour when we put the parachute out.
We can steer.
This is a picture of the camera on board the X-38.
There it is in a nice, gentle touchdown.
>> Now, were there people inside of this?
>> No, we flew these tests unmanned without people on them.
We landed pretty accurately.
We flew about ten miles and landed 100 feet away from the target.
That enables us to test it more a aggressively and take more risks and more
chances because we didn't have people on board.
>> It gives us a better understanding of an example of a prototype and doing a
test drop like the students will have to do with their aircraft they're designing
as well.
I hope you're getting your aircraft to stay aloft for five seconds and travel the
meter which is what your goal is.
If there are any ways that we can help you come up with ideas to overcome the obstacles you might be facing, let us know.
Hi there, we want to say hi to smart lab in Ohio.
Thanks for joining us today.
We've got team Houston's problem from Iowa.
Got a question.
They want to know what the biggest and smallest wind tunnels are and where they're located and do we use them.
>> Oh, yes, we do a lot of wind tunnel testing as part of the X-38 program.
There are wind tunnels that are owned by universities, owned by NASA, some owned by the military services, and some that are owned by private companies that do their testing and sell wind tunnel time and they're all different because they deal with different speeds and different altitudes that you could fly at.
The models range from literally no bigger than a model this size.
This is a scale model we have of the X38.
When we flew in one wind tunnel we flew a model about this size to ones that are very small.
NASA has some very large wind tunnels at Ames Research Center in California and at Langley Research Center in Virginia.
Those are areas where the wind flows through that are 20 or 30 feet in diameter.
>> Another question wants to know what energy sources could rovers use.
Is solar power a possibility?
How do rovers operate remotely?
>> There is a couple of different ways you can do that in terms of electrical
power sources.
And one of which is to use solar power.
In other words, use cells that gather solar energy and turn it into electrical
energy.
It's a common way to use it and it is good for plan either that are close to the
sun.
Good mercury, venous, earth and Mars.
Much beyond Mars it doesn't work very far because there isn't much solar energy.
People tend to go with a nuclear power source, something that works by generating electrical power by the decay of radioactive materials.
>> We have a 5th grade student named William wants the know how is chemistry useful in designing an aircraft?
>> Very much.
A lot of very important ways.
One of the most critical chemistry items we deal with is the thermal protection
system on the bottom of space crafts.
They're flying fast when they come into a earth's atmosphere.
It would fly about 17,000 miles-per-hour.
It's very fast and flying so fast that when it hits the upper parts of the
atmosphere the frictional heating that occurs raises the temperature of the
vehicle up very high.
When that happens all sorts of interesting chemical reactions happen on the
surface and we employ in NASA chemists who all they do all day long is worry about the different chemical reactions that occur on the outer part of the spacecraft.
Another area where we use chemistry, how we generate electrical power.
Close to earth where we have spacecraft that can be refueled like the shuttle we use chemical reactions to generate electrical energy.
>> Wonderful question, William.
Thanks for sending that in.
Let's go back to the chat room and see what other questions have come in for us.
We have someone, they want to know how long does it take to design a prototype vehicle?
>> Okay.
Well, that can depend on how complicated the vehicle is.
But it is not uncommon for a five to six years to go from an idea to a full scale
vehicle up and testing and flying.
On the X-38 program it took us three years to go from when we first started the idea to when we got our first test flight off.
That was unusually fast.
Five years is average.
What a lot of programs do is they build a lot of smaller sub scale or test
vehicles which enable them to build the vehicles quickly for flying and testing.
It's a a way to get results early in a program.
>> Looks like smart lab in Ohio has chosen Mars to be the other site that they
would like for their aircraft to fly.
They've got some questions about that.
They want to know, what aspects of the Mars surface and the atmosphere and the weather would be similar to earth's?
>> Well, the basic constituents in the Mars atmosphere are the same as earth but in different percentages.
That is very important because it affects the density or how many molecules are in a given set of air.
That's important because the amount of lift that a vehicle can generate is a
function of the density of the air hitting it.
You can affect the density of the air hitting it -- you can -- the effect of the
air on hitting the vehicle in two ways.
You can fly faster and the other is you can fly in denseer atmosphere.
It's why we fly very fast in the atmosphere and as we come down lower we slow down.
If you were at Mars you would be at the I can -- equivalent of flying high.
They have to be lightweight or have very big wings.
>> Pedro is a 4th grade student.
He wants to know if ion engines could speed up a trip to Mars.
>> Yes, they can.
We have an ion engine we've been working on here.
The neat thing about them is that when the ions come out of the engine they come at a very high speed.
And that -- and a rocket can only go as fast as the things that are coming out the back of it going in the opposite direction.
So when you're going as fast as the things are leaving the back end of the rocket can't accelerator move any faster.
The advantage of an ion engine it shovs them out of the back very fast and you can continue to accelerate.
It can cut the transit time from a year down to two months.
>> Many students are about at the halfway mark of their design challenges right now.
We want to know what kinds of things do you typically see when you're at the
halfway point of a project like the students are working on today?
What kinds of things should the students be seeing and experiencing?
>> Okay.
I think probably the best thing to gauge as you get to the halfway point are, what are the things that you still don't know about the design?
Those are the things that cause project managers to lose a lot of sleep at night.
If you're about your halfway point you should be going, what are the things that
we know?
We know how they're going to work and we've tested them a little bit to know that they'll work and what things haven't?
For example.
If you're designing a vehicle with a wing, a good test to have done by the halfway point is to build the first wing and put some weights on it to convince yourself that the wing will be able to support the weight of the airplane when it's flying through the air.
If the wing can't support the weight of the airplane it will fold up and you won't
be able to fly.
That's an important thing to know.
In the same way it's important to know what you don't know at the halfway point.
I don't know how it is going to land.
I don't know how we're going to build part of the fuselage.
Those are the areas that you need to start to put some more time and effort into.
>> Well, John, speaking of how is it going to land, we've got a question from team Apollo 5, 6, 7 from Iowa.
Hi there.
They want to know how fast the X-38 is going when it hits the X in the desert.
>> Okay.
Actually the neat thing about the big wing is that it enables us to fly really
slowly.
When we have the big wing all the way out, we're flying at about 35 miles-per-hour which isn't very fast.
Now, that is the advantage of the big parachute.
If they flew without the big wing and just flew with the lifting body coming into
land we could actually land it on the runway but because it has such a small
lifting surface we would be flying more like 250 miles-per-hour.
The important thing to know is that your landing speed is a function of how much lift you've got or how big your wing is and a function of your weight.
You can be -- the heavier you are or the smaller your wing the faster you land.
>> Okay.
Thank you.
All right.
Looks like Dan from Iowa is considering fuel cells for his project and he wants to know if a fuel cell could ever be powerful enough to play a plane as big as a 747.
>> Not one fuel cell but a whole bunch.
This would be like -- you can think of a fuel cell as a battery.
If you want to run electric motors which is what you do with fuel cells you need more of them.
NASA has a vehicle based on fuel cells that flies very high in the earth's
atmosphere so it is very doable and a great idea.
The problem with fuel cells is is that they use propelents.
If you want to use one for flying in the earth's atmosphere for several hours you
can use fuel cells.
If you want to fly longer than that you have to find a way to make the propelent.
One of the ideas that has been set up and discussed for these NASA airplanes would be actually to capture solar energy, get -- bring in water vapor from the
atmosphere and break the water into hydrogen and oxygen to feed the fuel cell.
You could be generating your power at the same time you're flying through the
atmosphere.
>> Our space shuttle uses an external tank and our solid rocket boosters which also use the combination of the hydrogen and oxygen you're talking about.
>> In a different kind of reaction.
This is where the chemistry dials into.
In the bottom -- in the shuttle, when we fire the main engines we're doing it in
the back we're firing a combustion reaction where we combine oxygen which is up in the front of the tank, hydrogen.
We combine them together and light them with a spark and really that's all there is to the main engines.
Tremendous technology in the pumps and making it all work and the temperature variations that happen in there but it is basically oxygen, hydrogen and sparks.
In a fuel cell which we use for power, what we do is we combine the molecules and they generate electrical power when they do it.
It's a much more gentle reaction than the back end of a rocket engine.
>> All right.
Well, smart lab has got a whopper of a question for us here.
They've been reading up on the Japanese Mars orbiter and know it had a problem because it didn't have fuel.
How much of spacecraft bulk is taken up by fuel?
Is it a lot is NASA researching other forms of energy that would take up less
space?
>> These guys are on the mark.
You're hitting all the right questions, guys.
These are the things that are really important to be thinking about.
Well, what I'm going to do is something that we call figures of merit.
They're handy numbers to keep around.
One figure of merit or a handy number to keep around.
If you're going from the earth to the moon in back for every pound you want to
take whether it's a pound of a person or equipment.
If you're going to go from the earth to the moon and back you have to carry 12 pounds of fuel.
If you want to go from earth to Mars and back with a conventional rocket
technology it is closer to 25 pounds of fuel.
You carry way more rocket fuel than you ever carry in equipment on the order of 10 to 20 times the amount.
>> Well, as an add ition to that question smart lab wants to know because of that amount of fuel should knowing how much fuel go into the design of your spacecraft?
>> Yes, it's one of the most critical things.
Absolutely.
What you have to understand what the total fuel load is so that you know you don't have a spacecraft that is too heavy to proper tell where you want to go and Pell.
They asked a question about different technologies.
The ion engines are very good because they're very efficient with regard to fuel.Liquid oxygen and hydrogen engine although they generate a lot of thrust require large masses of fuel.
It depends on the rocket engine you choose as to the efficiency of the fuel.
>> What type of engine would be good to use on a planet with no oxygen?
Is that even a consideration?
>> It is, absolutely.
Because, for example, on our planet we have lots of oxygen in the atmosphere,
about 20%.
We can fly jet engines.
Where the air comes into the engine and we just mix it with fuel to burn it.
If you're on a planet that doesn't have any oxygen in the air you'll have to carry
an oxidizing material with you.
There are a number of different kinds of rocket fuels but most rockets work as a combination of an oxidizeer or something with oxygen in it or a fuel that you burn together.
If you're on a planet without any oxygen you probably have to bring it along with you.
>> We have another question from Mrs. Randall's fourth grade class.
They want to know how much would the lower gravity of Mars offset the thin
atmosphere for lift.
>> That is a very good question.
These are great.
Another great question.
This is amazing.
Tell you -- that's a very good question because it recognizes something very
important about engineering and designing of vehicles, which is that there are
tradeoffs and which is the more important factor?
Is the reduced gravity a bigger factor or is the reduced air density?
As it turns out, the gravity on Mars is much less but the density or the lack of
density of the Mars atmosphere is a much bigger factor.
It helps you that there is less gravity on Mars because you can build bigger wings without having to pay as big a weight penalty.
In the end it's the density that causes you the problem.
>> Speaking of the wings that you just talked about, John, our next question is, does the aircraft have to have wings?
Can it be a hover craft or a hang glider or parafoil?
>> In terms of the exercise you have the sky is the limit.
You can do anything you want to go do.
And you shouldn't be constrained to a normal airplane.
That there are lots of different ways to fly other than a traditional airplane
like you would see in a jetliner.
The X-38 showed you a couple.
It operates as a lifting body, doesn't have any wings, just finishes on the back
that we use for steering.
All the lift is generated by the air going over the body.
When it flies under the parafoil it flies in a whole different way.
You shouldn't constrain yourself in terms of how -- what you think of in terms of flying vehicles.
There is lots of ways to do it but you're always grappling with the same factors.
You have to overcome gravity.
>> It looks like we have a student using that creatist wanting to know if a round ship with a base would be faster to travel with than a traditional aircraft style.
>> A round ship with a base.
>> A sphere?
>> Use our imagination on that one.
I'm glad to see you guys thinking non-traditionally.
A lot of spacecraft shapes tend to be less like traditional airplane shapes
because they've got to be designed to do the mission of flying through the
atmosphere where there isn't -- flying through space where there isn't any
atmosphere.
The problem you get into is, round shapes generate lift.
For example, a golf ball generates quite a bit of lift when you hit it or a
baseball.
The problem is they also generate quite a bit of drag.
Whenever you make lift with an object, the trick is to make a very little bit of
drag.
Lift is the force when you're moving through the air that is pushing you up and
drag is the force which is slowing you down.
You can feel that when you stick your hand out a window of a car when you're
moving along.
Be careful how you do it.
But when you stick your hand out and put it in the air what you can do is feel the lift but also you can feel your hand being pulled back.
That is lift and drag combined.
The problem with round shapes is although they generate a tremendous amount of lift they generate a lot of drag.
The neat thing about traditional wings is they have a lot of lift with a minimum
amount of drag.
>> As we're talking about this, can you talk about the flying characteristics of
the X-38 body, the lifting body and how well did it fly in our atmosphere?
>> It actually flies pretty well.
It was one of the neat things we found about it.
Even though it doesn't look like a conventional airplane it flies well.
The handling qualities were similar to that of the shuttle even though the shuttle
has a much bigger wing area on it.
And a lot of the handling qualities are a function of the shape of the vehicle but
you can do a lot with the computers inside and how you control the control
surfaces.
So that actually you can make a vehicle appear to fly a lot better than it would
from its basic kind of shape.
It actually performed very well.
We flew it almost at the speed of sound and it flew very well.
>> You were mentioning earlier that it was the size of it that seemed really small to me in the air.
Here is a picture of it in scale to people.
How long did you say it was?
>> This particular one was 24 feet long.
And there you see some people inspecting it there after it had been built.
This one was built out of fiberglass and was one of the ones we did in the drop
test.
>> Well, John, I see that you've got quite a few little demonstrations and toys
for us to play with here today.
Can you share with us some of the things that you've brought?
>> Sure, I'd be happy to.
I wanted to bring some things that would give everybody some a additional ideas about what they could do.
And I thought about bringing you models of spacecraft we've already flown but I didn't want to constrain everybody to thinking about the things that we've already done before.
I went to my toy collection.
I love to collect toys of different kinds of spacecraft and I said let me grab
some of these toys and let's talk about what these designs in toys would mean.
So we can go through a couple of them and take a look at them.
I would start with this one and this is a lander toy.
This is a toy -- this was modeled after a real spacecraft, the lunar module that
we used to land people on the move from an old TV series called "lost in space."
It is not aerodynamic.
It doesn't have any wings but it has a big rocket engine on the bottom and little
legs to land on.
It would fly down and land like this.
Actually, this kind of vehicle was used to land on the moon but it also we built a trainer.
It actually can fly in the earth's atmosphere just fine.
We flew them at a research center in California and here.
They'll take off and fly perfectly fine in the atmosphere and they fly by
controlling the rocket engine.
The problem with this design is how do you protect it as it comes from space into the atmosphere when you deal with the atmospheric heating?
That would be impractical about this design how do you protect it from the
temperature.
In terms of flying in the earth's atmosphere or another planet this is a good kind
of design to consider.
Another thing that we could talk about would be this spacecraft here.
This is kind of an interesting design.
This came -- I know it may be hard for you to believe but in the 1970's there was a TV show called "space 1999."
Now it's in the past but at the time it was far in the future.
And they thought about this kind of design for a spacecraft.
It is kind of interesting when you look at it.
>> Looks like a long worm.
>> Yeah.
It's built by someone who was very concerned about the structural integrity and the rocket engines.
It has a lot of rocket engines on the back and it has pods on the side that it
could put fuel in and connecting it is a truss work.
It is very stiff and strong and the crew is in the front.
This kind of a space vehicle would be very good flying around in space or in
atmospheres with not very much air because it's not very -- it wouldn't have to
worry about aerodynamic drag and lift.
In the earth's atmosphere it wouldn't fly very practically.
>> We have another question in the chat room.
Send the questions.
We're trying to answer as many as we can in the time we have today.
Carousel is a fourth grade student in Ms. Randall's class in Texas.
You guys have been sending in lots of questions.
Looks like their team is wanting to send a spacecraft to TITAN and they were
wondering how the thicker atmosphere there is going to affect lift on their
spacecraft.
>> Okay.
Flying in thicker atmosphere is like coming down in the earth's atmosphere and
flying very low.
And the neat thing about being in the thicker atmosphere is you don't have to fly very fast in order to generate a lot of lift.
But being in the denseer atmosphere your aircraft has to be very, very strong
because doing any maneuvers with it if you want to turn, for example, if you were going to do a turn the dense air pushing on it would have an effect to want to snap the wings off.
It would have to be very sturdy in order to fly but it wouldn't need lots of
engine power because the dense atmosphere would tend to buoy.
>> This boy is thinking about a sphere cone versus --
>> the way the X-38 shape started was a half cone.
You can see the center of it.
There is a shot of the X-24B which is another related vehicle.
It looks like a half cone.
The half cone is a very traditional good starting place for aerodynamic design.
You can get a lot of lift off the bottom yet a lot of good air flow off the top.
Warheads.
Old rocket vehicles, the Apollo vehicle was a cone vehicle, too.
I'm struggling a little with what -- he says the difference is between a sphere.
>> Maybe if he sends some clarifying words to us we can get more specific about the differences between those two.
>> Send those clarifications in for us so we can answer it for you.
Have another question.
What has been the most exciting part of any design project that you've ever worked on?
>> Got to be -- got to be when you fly it.
That is the most exciting thing is when you've worked for a time, you've put a lot of your hard work into a vehicle and then you actually the first time you let it
loose and it is up flying for the first time.
First flights are always the most exciting part and the most satisfying part of a
program.
>> Okay.
Got another complicated question here.
We want to know what is the difference between angle of attack and BURNULEE's principles in flight.
>> They're related.
This is great stuff.
Good questions.
You have to watch it.
I'll start acting like a professor and it might not be as much fun.
Angle of attack.I was in a course at the University of Houston last night for my doctorate and we were talking about this subject.
It may get boring here.
Angle of attack is the difference between where the nose of the vehicle is pointed and where the -- where the direction the vehicle is traveling, okay?
We normally think of airplanes as traveling wherever the nose is pointed.
I'm traveling like this and you can see the nose is pointed where I'm going.
That would be a 0 angle of attack.
As you pitch up the nose and fly this way, okay?
You see there is an angle generated between the axis of the vehicle and the
direction to which we're flying.
Here we go, the direction we're flying and the angle.
That angle is called the angle of attack.
The angle of attack determines how much lift a wing has or a body has.
And it's different for different shapes.
For example -- at different speeds.
Up high in the atmosphere the shuttle comes in flying at a 40 degree angle of
attack and noses over when we're coming in close to landing it is flying at 0
angle.
A typical fighter plane is 0.
An X-38 we never wanted to get below 38 angle of attack.
The other principles is about wings.
Let's hope I can do it right.
Basically it says that the reason a wing is curved is that the air traveling over
the top curve to the wing has to travel a different speed than the air coming down across the bottom of the wing because the number of molecules going into the front of the wing and coming out of the back of the wing have to be the same.
What happens is that means that the air speeds up over the top of a wing and that means that the pressure is less on the top of the wing and that is what generates lift.
And you can -- you can change the amount of the effect of the principle if you
increase the angle of attack.
That's how they're related.
>> Here is an exciting question.
The flyers team from Iowa wants to know if you've ever been in space.
>> No, I'm afraid not.
I really would like to.
I volunteered a couple of times.
It was really exciting getting to fly on the B-52 when we dropped the X-38 because we got up to the edge of space.
At one flight we were up over 50,000 feet.
When you look up at the sky it is starting to turn dark.
You can start to see -- it's beginning to turn a very dark blue, almost turning to
black.
And so I kind of felt like well I didn't quite make it.
That is only 10 miles up and we say astronauts in space start at 50 miles up.
I had a long way yet to go.
>> Great.
We've got lots more questions coming in in this chat room.
Nick from Iowa wants to know if you think someday we'll land a spacecraft on one of Jupiter's moves and which one of the 39 moves that Jupiter has we might land on?
>> I'll give it a try.
>From what I understand a lot of people are excited about UROPA because it has a frozen ice surface because it's so cold.
The outer surface is frozen and it appears to be water ice.
That implies that at someplace down underneath the surface of the planet there is probably liquid water.
There is the potential for life.
On the earth there has been living things discovered very deep in the ocean even though sunlight doesn't penetrate it where living things live on chemical
reactions from materials coming up from the center of the earth.
That moon is exciting to get to because of the potential of finding life in the
deep oceans.
>> I have a hard time believing there are 39 moons and still counting on Jupiter.
>> During our test flight how can we tell if it was actually flew or something
that was just thrown like a football?
>> I think one thing to do would be to measure the distance flown, okay?
And measure the time it took to fly that distance.
That would be a way to do that.
And compare that with dropping something straight of equal weight.
If you just drop something of equal weight down and you measure how long it would
-- how long it would -- how long it took to hit the ground and then you measured the time you were in the air it would tell you if you were really flying or just really falling like a rock.
If you were just -- gravity was having an effect.
Another way to do it would be to measure the angle.
To go ahead and measure how far you flew and how high you started flying and measure the angle.
The angle that you fly at is a measure of your lift to drag ratio, which is a
measure -- a figure of merit of the efficiency of your flying vehicle.
If it was over 1 you've made a good start.
If the ratio of the distance you flew to the altitude you flew is greater than 1.
If you get 2 to 3 you're doing very good.
>> That is a great guideline the students can graph it on a piece of paper using
the distance and time and do a couple of dry runs and see if they're consistent or if they seem to be gaining some -- that ratio of 1, 2 or 3.
>> If it's an airplane-type configuration with a tail if they adjust the angle the
tail is set it they can increase or decrease the lift depending how they do that.
>> We have a whole bunch more toys.
Can we see some more?
>> I'd be happy to.
This is an interesting spacecraft.
This was from a movie, a cartoon movie called Titan about a year-and-a-half ago.
The reason we got interested in the shape when we saw it in the movie we
recognized there was some good ideas about this shape.
You see it's got a cylinder on it.
It can generate lift the same way a wing can.
We actually went and did some computations and went in a wind tunnel and tested a shape like this to see how much lift we could generate.
We were interested because a cylinder is a very strong shape.
Think about your bicycle wheels.
They support a lot of weight but they're -- not very much metal inside a bicycle
wheel.
The reason is because the strength that you get from being in a circle is very
high.
We looked at it and it turns out this is an interesting shape and it looks good on
the movie but it doesn't generate a lot of lift and wouldn't fly very well in the
earth's atmosphere.
You need a ring three or four times this size.
If you built a ring three or four times this size it would fly as well as the
orbiter would fly.
It's a matter of how you do it.
It was interesting because the people who thought about this in addition to
thinking it looked cool actually started to address interesting issues because
they had a place for the pilot to sit with some windows.
There was a fuselage which was streamlined so that it didn't have much drag.
And then it had a device for generating lift and then it had propulsion in the
back.
Those were all the basic elements you have to have in a spacecraft.
>> What else have you got here?
>> Okay.
Another toy I like to collect is this is G.I. Joe's version of a space shuttle.
This is interesting because it's similar to a design that NASA did some work on
called the X-33.
If we can hold the X-33 up you can see it's the same basic shape.
The reason I want to use the bigger model is to talk about some things that the
people thought about when they were designing this.
This is just a toy, not a real thing that's been built and flown.
But there are some interesting things that were looked at in the design, one of
which was how much cargo it would need to carry.
It has kind of a bay door in here where you would carry cargo deep inside it.
One thing they thought about was where do the people sit?
There is a passenger compartment in front and it would have to have visibility so that the crew could fly the vehicle and so it's got windows in it, okay?
Another thing that they thought about was they noticed that there are different
colors of material on the shuttle and other spacecraft.
As it turns out the different colors are for the different amount of thermal
protection you need based on different parts of the spacecraft.
In a spacecraft coming into an earth's atmosphere or any atmosphere the nose gets the highest hitting because it's first to hit the atmosphere and smallest
diameter.
They thought about control surfaces here with fins on.
You use that for steering.
Then on the back end there is propulsion, rocket engines.
So they are integrating a lot of interesting even in this toy, you can see a lot
of interesting aspects.
How do we deal with the people, how do we deal with the pay load, how do we deal with controlling the vehicle.
How do we make the structure very solid.
You notice this is a nice, solid structure.
Easy to build and make strong.
It has lots of beautiful curves in it.
The aerodynamics people.
The people that have to worry about how the vehicle flies they love to see
beautiful curves.
It helps them with that.
It is interesting when you look at toy and make believe spacecraft you can see a lot of the aspects that affect real aircraft and spacecraft design.
>> Well, everyone.
We have about ten minutes left.
Take a moment and submit your questions so we can try to get those answered with our expert John here in the time that we've got left today.
Students, for those of you who haven't joined yet, you can still participate in
the Space Day challenges and you can also still hop on instead of just viewing our program today, join the chat room and submit a question.
You can go to the website Space Day.com to get more details on that.
And you can also find out more details in the chat room.
Michael wrote us back from -- and said the cone that he was referring to is a
sharp pointed cone that tapers sharply.
>> Okay.
Versus one -- now I understand what you're saying, versus one that's more blunt.
We've looked at blunt cones as a way of flying into the Mars atmosphere.
And it turns out it is a very good device for flying up high where it's very fast
but the sharper cones generate more lift.
Now, the problem with the sharp cones is that how hot you get as you come into an atmosphere is a function of how sharp the point is.
The sharper the point, the higher the heating that you get when you come in.
The blunter the point the less the heating.
But the sharper the point, the more lift you get.
And the blunter the point the less lift you get.
You have to trade off what you can make in terms of protecting it from temperature versus how much lift do you want to get.
>> Okay.
The students want to know what can they do if their test flight fails?
>> Try and try again.
Yes.
Actually, that happens to real engineers and real test flying.
On one of the flights of the X-38 we had a control system problem and actually rolled the vehicle all the way around and down to -- down around and there were a lot of hearts that stopped beating, including mine, when that happened.
So things going wrong in a flight test is not unusual.
That's a very usual thing to happen.
And an important part of doing aerospace engineering is knowing how to do the test so that you can -- so that you can move on to the next test.
Now, there are things you can do to reduce the risk when you're doing the test.
For a start you don't go up on top of the highest building you can find when you do your first test flight.
Try to do it in an area where it's not very high up and where you can put soft
pillows or cushions down to protect it when it first lands or on a soft carpet
rather than getting on hard land.
An important part of test flying is knowing how can I reduce the risk if something goes wrong we can go on and fly another day.
But the second thing to do is to watch what happens.
A good idea would be if you can get a video camera, videotape the test flight and then you can play the videotape slowly to see how the flight went.
Another thing might be to measure everything that you can.
Measure the weight of the vehicle before you fly it, measure the distance you
flew, measure the time that you flew and you can use those to understand how the vehicle is flying.
>> Okay.
A team from Iowa.
We have lots of teams in Iowa, great participation.
They want to know what kind of schooling do you recommend to become an astronaut or someone who is working in your field of aircraft design?
>> Okay.
First thing is if working with airplanes and spacecraft doesn't really make you
excited, this is the wrong job to have.
It's a field that can be very frustrating because you have some days where
everything goes great and then you have some days where everything falls apart.
You have to really love things that fly and if you're the kind of person that when people ask me if they should get into the space business or the airplane business I say when you walk outside and an airplane goes overhead do you look up and wonder what kind of airplane it is and how cool it is it's flying?
If you're that kind of person then aerospace, engineering could be exciting for
you.
The thing is to study science or engineering.
That means having a lot of math in your background also.
It's very important to study science and math and really there is openings in the
space business for almost any field of science and math.
Whether you're a medical doctor and you're interested in the effects of flight on
a human's health or whether you're a chemist like we said and interested in the
chemistry of rocket engines.
Whether you're an engineer that designs the structure or a computer specialist
that programs the computers.
Pretty much every field of engineering and science is used in the space business.
>> So the students do need a college degree in that area.
>> Absolutely.
It is very hard to do work in the field unless you've gone all that way.
>> Hear that, everybody?
Keep up those studies and keep working on these types of challenges in your
classroom going above and beyond and applying that in the future to your college studies and who knows, we want you to come here and be a member of our team here at NASA.
We have 10 NASA centers across the United States.
Lots of places and ways for you to contribute to the space program.
That would be very exciting.
Got another question from a team from Iowa.
For making their models fly they've used several propulsion methods.
Some of them have been ALKA-SELZER and rubber bands.
Can you think of any other methods?
>> I was going to say the rubber band idea.
Impart an initial velocity and basically pull the rubber band back and let it
throw the vehicle like a slingshot.
Another of which is to put a propeller on the vehicle and use the energy stored in the rubber band to go ahead and turn the propeller.
If you can take a propeller and bury it inside a cowling, inside a circle you can
make a primitive jet engine that way.
It's a little harder to do and to get the air flow right.
The chemical idea as a chemical rocket is a great idea.
ALKA-SELZER is a great source of carbon dioxide.
One thing you might think about is taking water.
It is a great project you can take water inside like a soda bottle, a one liter
plastic soda bottle and you can pump up water and air with a bicycle pump and generate a tremendous amount of pressure in the bottle.
When you release it the force of the material coming out of the bottle will
actually fly the bottle up 10, 15 feet in the air.
You can look at compressed air or you could look at compressed water.
Those would be some very simple working fluids you could work with.
Any system that has compression in it is going to be a little heavier so you'll
need a little bigger wings to work with it.
You can get thrust out of it.
>> Okay.
All right.
John, we have had just a lot of questions coming into our chat room today and we tried to get through as many as we could.
We have about -- about two or three minutes left today and a couple of closing comments we need to make.
Want to let you know if you missed some of the details that John so painstakingly helped us out with today, this program will be archived on the Quest website within a couple of days and you can go back and watch it and take more detailed notes and catch any parts that you may have missed that will help you out with your design challenge.
We do want to thank our partners at the Challenger center in greater Washington and, of course, Ames NASA Quest program who is helping us bring this program to you today.
And our Space Day 2003 friends for these wonderful challenges and a great
opportunity for the students out there to be working on these advanced principles and really bringing them into the classroom.
Students, if you have an awesome teacher that you would like to nominate for our educator astronaut program.
It's a brand new program we have where you can nominate your teacher to go to space, you can go to the website at ED space at NASA.gov.
It doesn't mean your teacher will have to fill out an application.
It is you taking the time to say I have a great teacher and I would like to
recommend my teacher be nominated to apply to the educator astronaut program.
So take a moment and do that.
We'll put that website in the chat room as well so you can have access to it.
Well --
>> round trip, right?
>> It is a round trip.
>> The teacher has to come back.
>> We're not sending them out to space for good.
Don't think you'll try to get rid of them that way.
They'll be coming back to the classroom.
Thank you for the wonderful information you've shared with all of us today.
I know we've all learned a lot.
Do you have any closing comments for the students?
>> I want to tell you these were really great questions and it is obvious you are
thinking hard by the and coming up with great ideas and digging into the details.
I guess the big thing to remember is that in building vehicles, it really takes a
team because you have to use skills from lots of different people.
Even though on your small projects you may not need lots of different people to do it, it is a great experience to practice working as a team because building real airplanes and spacecraft requires a lot of teamwork.
>> There will be the third and final design challenge tomorrow at 12 noon central. We'll have another WebCast just like this and that design challenge entitled "Watt Power!".
Be sure to join the WebCast tomorrow to learn about that.
We'll have another NASA expert available for you.
It's all the time we have today.
We hope you've had fun and learned a lot and are inspired and have some solutions now to your design challenges.
Until next time, John and I say so long from Johnson Space Center.
Bye-bye.