Culmination of PSA Microgravity Design Challenge
Hear from NASA engineers. See what NASA is now doing to test the PSA on
Earth to determine how it will behave on the International Space Station
and find out what they have to say about your designs.
information on this event is available
Read bio of expert Daniel Andrews
>> Command initialization sequence.
>> Explore space, explore Earth, talk to the people who work at
NASA and see what you can really do with science.
Students, teachers can go online with NASA.
It's easy on the Internet at quest.org.NASA.gov.
>> Good morning and welcome to the webcast for the PSA microgravity
I'm Alicia and I would like to welcome the students and teachers who worked
so hard in creating their design for testing the Personal Satellite Assistant
or NASA's robotic helper.
I want to start by reminding you that we'll be answering your questions
during the online chatroom.
We'll try to answer as many of them as we can.
Dan Andrews is with us today.
Thank you for sharing your time here with us at NASA Quest.
>> You bet.
>> Before we get started I want to give you an overview of what
we'll be talking about today.
We'll talk about the challenge, why is it necessary to simulate microgravity
on earth and the six degrees of freedom and why they're important to PSA.
Next Dan will take a look at each of the final designs submitted by you,
We'll look at other testbeds or places NASA uses to simulate microgravity
and finally we'll learn about what the PSA engineers came up with for
testing their tiny robots.
We'll finish the webcast by answering your questions submitted through
the online chatroom.
Make sure to get your questions in.
Let's get started.
Probably the first thing we need to talk about is what is microgravity?
PSA is a robot designed to operate in a microgravity environment on the
International Space Station.
When we say the word microgravity, what is it that we mean?
The astronauts inside the International Space Station take a trip around
the world every few minutes.
In a car you can only go 60 to 70 miles-per-hour.
The astronauts are traveling at 17,500 miles-per-hour.
That just happens to be the magic speed.
It's just the right speed to balance with the gravity that Earth is pulling
on the Space Station.
As the gravity of the Earth pulls on the Space Station the Space Station
is going fast enough to keep curving around the earth and curving around
and around it goes and it achieves orbit.
It keeps curving.
That's what we call orbit.
That's the State of free fall that gives us the thing we call microgravity.
So let's take a look at some footage of inside the International Space
Station to show us exactly what that looks like.
>> The astronaut is moving and can pull himself a little put and
float a little bit.
It's one of the principal ideas of microgravity.
It keeps floating right along.
That's very important from the standpoint of the -- of the testbed that
we test something that would go up into space.
>> That's what we would like for you to talk about, Dan, is why
is that important?
What are the things you need to know about the microgravity environment
that can test something like PSA?
>> The main reason we wish to have a microgravity testbed is because
if we didn't have something like that, we built up a robot and then we
brought it up into the Space Station or on any spacecraft in general and
we didn't have a high -- we didn't believe that it would actually work
or we weren't sure it would work we couldn't go up there and fix it.
When astronauts are up there, it is expensive to get up there and we want
to believe it works.
While we're here on Earth we want to create an environment much like the
one you guys designed that can allow us to test while we're here on Earth
and get our confidence up that the thing we'll be bringing on the spacecraft
is really going to work.
Before we get into the student designs which I'm anxious to do, I wanted
to point out that there is no perfect testbed.
This is true for us as well as for you.
When you guys were going through this you probably noticed that you were
working on one part of it and that made something else not work so good,
or it was not possible to get this other thing working.
So we know what you're going through and we had to go through the same
Before we get into the student designs, though, I wanted to talk about
a concept of movement.
Every object has a certain number of degrees of freedom movement.
And in the case of the PSA or any object that will be up there in space
it is important to understand these.
We'll begin with some diagrams of a jet and use that to explain what these
degrees of freedom are and I'll explain it with the PSA itself.
In this picture that you see right here, we have a jet that is moving
It could also technically move backwards even though that would be hard
for a jet to do.
This one degree of freedom is called the X axis.
Forward and backward.
The next picture shows side to side movement, to left and to right.
This is called the Y axis movement.
We're not turning, we're moving totally to the left and totally to the
The next slide shows what we call the Z axis, this is pure up and down.
So you see those are the three degrees of freedom that have to do with
motion in a line, forward/backward, left/right, up/down.
Three other degrees of freedom have to do with how you turn.
In the next slide you see the first principal degree of turning which
is in this case pitch is shown.
And this is where the nose moves up or down rotating the entire body that
And the next slide we see roll.
This is a case where in this diagram here the wing tips are rolling to
the left or rolling to the right.
And then the final slide shows yaw.
Where the nose turns to the left and to the right.
Some of these may be familiar to your in your everyday life.
When you're riding a bicycle you can move forward and backward in X.
Turn to the left and right and that would be a yaw motion.
Can you move up and down?
So your bicycle isn't seen as having the Z axis degree of freedom.
Now I'll show you basically the same things with respect to the PSA.
This is a mock-up of the PSA.
It doesn't work but it gives us a good illustration of what it is and
how it will fly.
So let's go through those six degrees of freedom again.
In the case of the X axis, if this is the front of the PSA an X axis movement
would be in and out, forwards and backwards, all right?
That would be left to right.
Side to side motion.
You'll notice I'm not turning it, just pure side to side motion.
Then the Z axis would be up and down.
Now for the turning degrees of freedom you have the pitch axis where you're
tilting up and tilting down.
Notice I'm not moving in and out know.
Those are the other degrees of freedom.
Just tilting up and down and you have the roll axis and in that case you're
rolling this way left and right.
And then the final one is the yaw axis where you're turning to the left
like you turn your head or something, turn to the left and turn to the
So those are the six ways in which an object in space can move or even
here on earth.
Our testbed should provide as many of those as possible.
I want to go through the student designs in this light and talk to you
about, you know, what I witnessed and some of the clever things that I
The first design is from new market middle school.
It's 8th graders John, David, holly, Kate and Macy.
This is the best picture we had of it.
It appears to be what I would call a 2 degree of freedom system.
The 2 degrees of freedom I'm seeing are X.
In this case you see a chain mechanism on an overall rectangular structure.
This is represented as a tennis ball on a string.
The X motion would be forward and backward along this chain.
The other degree of freedom that I saw was yaw.
In that case remember yaw is like turning your head left and right.
If the PSA is hung from a string there is a yaw motion.
Limited yaw degree of freedom.
I like this, 2 degrees of freedom covered and I especially liked the comments
I heard from this group.
They were intending on also providing a Z axis the up and down.
But as they put it their enrichment funds ran out.
And I thought that -- it made me laugh because that's exactly the world
that we live in.
It's fine to be able to design these things and have great ideas but you
have to live within the real world of your budget of how much money you
have and so I was very sympathetic to your situation.
The next is from new market middle school, another 8th grade group.
In this case the structure looks kind of similar.
I believe they used a coonect system to build this and I would say the
principal difference I was able to figure out, this one is a 3 degree
of freedom system.
It has the X axis along the chain system here so the ball can move this
The ballet tachd -- ball attached by a string can yaw.
They were also able to put a motor system up top that should be able to
lift the ball up and down so that would be the Z axis.
I'm counting three degrees of freedom on this one.
Another good design.
The next final design was Caroline Robbins community school in Canada,
a fourth and fifth grade group.
What I'm seeing here is a two degree of freedom system.
I think it was intended to be maybe three degrees.
We'll talk about that in a bit.
What the basic structure is a remote control skateboard, a powered skateboard.
The PSA represented by the tennis ball is supported by a string that goes
through the PSA.
And so the PSA can potentially move on the string.
It can also go in the same X degree of freedom by moving the skateboard
forward and backward.
And the degree of freedom I don't know if it was intended or not.
Another one I see here is roll.
That is, if you put the string directly through the center of the tennis
ball where it's balanced, where it won't wobble you could actually roll
If this were a real PSA that had jet thrusters you could actually spin
on the string.
A degree of freedom maybe you hadn't intended.
I think they had a Z axis that you pulled on a string and it brought the
tennis ball down and up.
In this case I think you wanted to be able to have the PSA move up and
down on its own and in this case you had to pull it by a string.
Let's say it's probably principally a two degree of freedom system.
This is a motorized toy skateboard.
If this were a real PSA what might be interesting is to use a real skateboard,
one not powered at all on a really smooth surface with really hard wheels.
Because then when the PSA tried to move forward in X the wheels would
start rolling and they could keep rolling until it eventually slowed down
because of friction and other reasons but you wouldn't actually need to
It is something to think about.
The final submission that we have here is from new market middle school,
a 6th grade group.
Jordan, Chris, Michael, Michael and Al.
This one I really liked because I was able to detect four degrees of freedom
The Z axis design is handled very well here.
You notice they used helium balloons probably around Valentine's Day by
the look of it.
This is a great design.
What has happened here is that all of the weight of the PSA, the tennis
ball and other equipment that they've put down here is neutralized by
having enough helium balloons up above.
The PSA has no weight, in effect.
And so right here on Earth they've provided a degree of freedom where
it has no weight so the PSA tried to thrust up it would, tried to trust
down it could.
If it wanted to go in X and Y it could.
And in yaw.
If you had this hanging from a string you should actually be able to yaw
on getting four degrees of freedom here.
So very good design.
With that I'm going to turn it over to Alicia on the things that NASA
uses to be able to create microgravity-like environment.
>> Good work by the students.
We'll talk about a couple of the things that NASA does in order to simulate
There are a lot of people walking around out there who think that NASA
has special magic room where you just switch off microgravity and tables
and chairs and people and things start floating up and you float around
and that's how we test equipment and that's how we train astronauts and
people have seen these things on TV and they think somewhere this magic
room exists behind this curtain somewhere.
You'd be surprised at how many people really believe that NASA has that
capability to switch off microgravity.
Is it possible?
Can you just turn off microgravity?
The answer is not even close.
You just can't do it.
We're living on a big giant rock that has a lot of gravity.
There is really no way to get away from that gravitational force.
We can stall.
NASA does a lot of things to create free fall so we have simulated microgravity
on this planet.
There is three main ways that NASA uses to do this.
One of the ways is a drop tower.
If we look on the screen.
Drop tower uses a concept of an elevator and so if you've ever ridden
in an elevator and as the elevator moves down you feel the lurch in your
Your stomach knows in you're falling.
Parts of your body can sense this whether you perceive it or not.
That split second of falling that your body recognizes as free fall.
Now, the drop tower uses kind of this idea of dropping something only
they drop it really fast.
It's almost as if you were in the elevator and the cable broke and you
fell to the bottom of the building.
If we look at the next photo is the drop tower at Glenn Research Center
They put the experiments inside these boxes and packages and they're able
to test a variety of things in there.
They put in video cameras, microprocessor center to find out what is going
on in the experiments.
Suspend it to level eight and they release the package and it drops 80
feet to the bottom.
It does that in 2.3 seconds.
We'll look at a video of that happening and you'll see how quickly that
That's a pretty quick drop.
Let's see if we can watch it again.
I think we'll show it one more time to see how quickly that really happens.
You have your experiments inside.
You send along a video camera or other equipment to watch that drop.
But again it only takes 2.2 seconds.
It is not very long that you have microgravity in that environment.
Now, Dan, would this be a good way?
We'll watch it one more time.
There we go.
So Dan, why or why not is this drop tower a good idea for testing something
like a PSA?
>> Drop tower for the PSA probably not a great idea.
There are a number of reasons why.
First of all, the 2.2 seconds is not much time for us to be able to see
how well the PSA is doing in that one degree of freedom as Alicia described
This is a Z axis degree of freedom testbed and so you have 2.2 seconds
to be able to see how the PSA is performing.
Not much time.
Secondly, with respect to X and Y, you can't do a lot of X and Y movement.
You probably could do the rotational degrees of freedom.
Not much time.
The thing that would worry me is the landing.
The PSA is designed to be tough enough to withstand flying around, bumping,
handling, things like that to hand even in a box of cushions would make
me worried about the health of the electronics.
>> So drop tower is out for testing PSA.
Let's look at another way the astronauts train to work in micrograve Mike
-- microgravity at the pool.
It's located at Johnson Space Center in Houston, Texas, this swimming
pool has 6.2 million gallons of water.
It's large enough that they can pull full-size mock-ups of the International
Space Station models, Hubble space telescope or any equipment to have
astronauts train on in microgravity.
These astronauts are wearing a 300 pound space suits, dive tanks and they
go into the pool.
The name of the pool is the neutral buoyancy.
They mean the astronauts have enough weight so they don't sink and don't
They're in the middle stage so it's simulating microgravity.
They're not falling, just in between a float and sink.
In that environment they can experience the pushes and pulls of what it
would be like to work in a weightless microgravity environment.
Now, again, thinking about this as a testbed for PSA this may or may not
be appropriate and Dan will tell us why that is.
>> This idea of a tank in which the PSA can work is a much better
idea than the drop tower.
First of all, one of the benefits it has over the previous is you can
be down there in this environment for a long time so you could check things
You have sufficient time to be able to see how your PSA a doing.
It's also very large so you can move in X and Y and all six degrees of
From that standpoint it works well.
The big problem is it's in water and the PSA is designed with first of
all very porous with holes to get rid of heat.
It moves by sucking in air from the sides and pushing out air from the
We would be sucking out water and pushing out water and it would destroy
Not such a good idea.
Even if we design this differently so it could, you know, withstand being
in water, it would be very time consuming, very expensive and wouldn't
really be very beneficial for flying it on a spacecraft anyhow.
So why would you want to do it?
Probably not a very good testbed, either.
>> I think we have some video of astronauts working in the buoyancy
You can get a sense for how it simulates microgravity.
An astronaut is putting on the suit.
Big heavy pieces of equipment and lower them by crane into the pool to
get them in there.
So NBO not a good choice for the PSA.
Let's get something a little bit closer to microgravity.
That's an experimental aircraft called the KC135.
One of NASA's research aircraft located in Houston, Texas and also called
a vomit comet.
I'll talk to you about why it's called that in a minute here.
When people see footage of the vomit comet this is where they get that
magic room idea that NASA has the ability to take microgravity away.
It can do that for almost 30 seconds worth of time.
If we look at a diagram here, this is a picture of the flight path of
the KC135 that goes up to 25,000 feet and flies in these arcs and curves
and does 30 to 40 of these in a two-hour time period.
You're going up and down very fast.
If you look, it almost looks like a track of a rollercoaster.
That's the basic idea here.
If you've ever ridden on a rollercoaster and the split second you go over
the top of the rollercoaster and get that feeling in your stomach.
Your body knows when you're falling and it's true in the rollercoaster
that few seconds of free fall.
An airplane can achieve that for 30 seconds.
It's one heck of a rollercoaster ride.
They do it 30 to 40 time, hence the name vomit comet.
I had the pleasure of riding on it about a month ago and while I didn't
have the ill effects, I can't say that for all of my research team members.
So it's very appropriately named as the vomit comet.
So at this point in the PSA's development why would KC135 not be a good
idea for a PSA?
>> The KC135 is probably the very best option of the ones that we've
heard about today.
It has a longer period of time of weightlessness, more than the 2.2 seconds
for the drop tower and no water, that's a good thing.
The limitations are, of course, that because it's still on the order of
a handful of seconds, 20 or so seconds you have a limited time in which
you can set up the PSA, get it initialized before you're coming down the
other side of the arc of the aircraft's movement which is then bringing
You're spending a lot of time releasing and catching your test article.
>> I think you actually have some video footage of a similar kind
of experiment being flown on the KC135 and you'll see that in the video
and you can go ahead and narrate.
>> These are similar robots being tested.
You see how the robot goes up and it comes back down.
What you're seeing is the aircraft going through its arcs, right?
Right there it has no gravity and they fly up and capture it and then
you'll see it again where, you know, it is starting to fall down.
They're making the arc with the aircraft and gravity is essentially coming
back into the equation again.
As you can see from that video, there is not a lot of time to test stuff.
It is more of a, you know, course test of does the thing go crazy?
Does it fly into a wall or do something terrible.
As far as precision tuning, not a lot of time.
That being said, once we get passed Earth-based testing we'll end up going
on it because it's a final check before you actually put something up
>> You want anybody to help you out with that, let me know.
>> Very good.
Want to remind you we'll be answering your questions near the end of the
If you have a question, submit them online in the web chat right now.
Dan, we've talked about drop tower, we've talked about the KC135, the
neutral buoyancy left.
None of these are a good test site.
What did you develop to make the PSA an effective robot?
>> Be happy to.
I want to go ahead and show some of the things we entertained.
I know you folks out there, when you were designing these things, you
probably had at first this great idea.
When you dug into it further you realized not such a great idea, too expensive
or too hard to make such a big thing or whatever.
We went through all the same stuff.
We have a video of one of our first ideas of using a mobile.
I don't know how many of you are familiar with the idea of a mobile but
you might have seen it in your baby sister or baby brother's room.
Supported by two strings you hang from the ceiling.
When you push on it, it has very free motion.
We thought that would be great for the PSA.
We would make a very big mobile.
And we looked into that and then in this video you see now you see the
square cube there?
We picked that so it would be easy to figure out from the weight.
That would be the PSA.
It worked fine most of the time.
It was able to move as the PSA requested it move but it had limited range
of motion, kind of like with some of the other examples you gave.
We have limited time.
In this case we have all the time we need but you have a limited range
in what you can move.
There are degrees of freedom missing.
Can you move up and down with a mobile?
Not very well.
You can tilt the rods back and forth but not a good Z axis device.
We bagged that.
The next item we decided to use a blimp.
Not like the ones you see at the football games but the idea of a helium
One of the student groups came up with an idea very similar to what we
We probably weren't going to use Valentine's Day balloons but create a
big bag filled with helium to eliminate the weight of the PSA and then
from there we could go ahead and test it in many of the degrees of freedom.
The problem that we saw with this was that when you're carrying helium
balloons and walking on a windy day, the balloons really move a lot and
the wind tugs on them.
You don't want that to happen to the PSA.
If the PSA is trying to make a fast move the balloons will actually tug
on the PSA.
The whole point of the microgravity test facility idea -- the testbed
is to be able to allow the PSA to move as if it thinks it's in microgravity
so it's not being tugged on.
We thought maybe not the ideal solution.
Then we moved on to another possibility and this is sort of an air hockey
We have a sort of a scientific version of an air hockey table.
You can see that video.
What this does is the ability to move in X and in Y, you see a very early
version of the PSA moving on the granite table.
It can move in X, Y and yaw.
It can turn or twist.
Can't move up and down so it's less ideal in that way but we did a lot
of testing with this that allowed us to get smart about how to control.
There has been to -- the thing that controls what the robot does and how
From there we went on to other versions of the PSA.
In the next video you'll see a PSA that is starting to look more like
It's not red or not quite circular.
Here we're doing pure yaw testing.
I didn't explain before but there is no air coming out of the table.
The table is just a hard, very flat piece of granite.
The air is coming out of the bottom of that disk that the PSA is sitting
We have a little aquarium pump on there that is pumping out air and puts
a little tiny air gap between the plate and the granite table which makes
it move as if it's floating.
In the next video you'll see the equivalent of that for the X axis where
the PSA actually translates, actually moves along a line.
Here we're being -- commanding the PSA from the guys you see behind the
computer to drive to the other end of the table.
And someone catches it and sends it back on its way.
So this is getting pretty good.
We can do a lot of good testing here.
Yes, we can't move up and down and we can't do some of the orientation
or rolling changes, but we got very, you know, got a lot of stuff done
in that arrangement.
When you get past that you have to think how do we get all six degrees
We went to the next step and that is to create our microgravity test facility.
You'll see a video now of the facility being tested in spinning.
So this is being keyed up right now.
We don't have the PSA in there, we have just a dummy weight.
That red disk is a weight that weighs the same as the PSA but allows us
to see how it works.
You see how it spins and spins.
That's not being driven by a motor.
That's where our three second criteria came from in this challenge.
Here you see the same device and here Mike is going to push on this device
and it keeps floating.
You go to the other side and slow it down and push it back.
So this is really at the heart of simulating microgravity.
Up above is a whole mechanism that I'll be talking about in a little bit
that is allowing this to happen.
This is looking pretty good.
In the next video we see the next step beyond that.
We start to see it moving in Z as well and even tumbling.
Doing a little more testing on pushing and pulling on it.
What we want to go to now is showing the PSA in what's called a gimble.
It's supported on a horizontal Saturn ring.
The PSA can move in all six degrees of freedom in this case.
It can move in X, Y, Z, up/down, left/right, forward/backward and it can
roll, pitch and yaw.
Mike set it up for some movement here and the PSA right now is driving.
You can't hear it because there is no sound on this video but it is actually
pushing around right now.
>> The whole idea while the PSA is moving in this environment it
shouldn't sense there is anything touching it or hanging onto it.
As far as it's concerned it's in microgravity.
>> That would be the perfect microgravity environment.
>> These are different ways of allowing it different ways to move
in six degrees of freedom to achieve that.
>> You can't get it perfect but if you get it good enough so that
you can tune your robot so your robot can move as close as possible to
the way it will when it's up in space, then by the time you get up there
you're pretty confident that this will really work.
If you didn't have something like this, there is a good chance it won't
>> We would spend a lot of time and money invested in something--
>> And we can't go and fix it.
>> We have to make sure it's done before you send it up.
>> It's worth doing.
I think we have more video coming up of the PSA doing some more movement.
>> How big is what we're looking at right now?
>> That's a good question.
The room size is very close -- very, very close to the size of the actual
And so we're looking at about nine feet along the floor, nine feet up
the sides, plus or minus and 30 feet long.
This is a great video here where you see the PSA being pushed toward the
No one is touching it right now.
It's rolling toward the camera.
We have Mike there to catch it but it was doing that on its own.
The PSA wasn't driving it in that case, Mike is pushing it.
It illustrates how good this microgravity testbed is.
When you touch it, it just starts spinning and that's what you want it
to do to keep going.
>> So it's like in the earlier video passing a can of food across
Give it a push and there it goes.
>> We want to create an environment where that is the case.
Here you see a combination of X, Y, Z and I would call that all six degrees
of freedom because it's rolling all over the place.
So you'll notice when we look at this it has a feel like it's in space.
Other than the fact that Mike isn't floating, it really looks that might
be on a spaceship.
And so it's working very well for us.
>> So I think -- is this the last video?
I think that might be the last video that we have of the PSA operating.
What I want to talk about now is how we did it, what is that mechanism?
So -- let's see, do we have some video of motion on the Space Station
I think we might have some of that.
Yeah, here we go.
This is just to reinforce what you just saw.
You notice the motion there?
Nobody is touching it.
Someone touched it at first but now it's just tumbling.
This is the true microgravity.
Where gravity isn't having a major influence of it but things are going
where they are let go.
Those are gummy bears or something.
See how fluid and how the movement just continues?
So again this reinforces just how well the microgravity test facility
is working and how well we wish it could work.
There is a little blob of water.
It will stop shaking because there is no gravity there to cause it to
drop or change shop.
Now we'll talk about the test facility.
What the test facility is, we have some slides of its early development.
This is an animated picture that we have from an actual design tool that
we used to design the crane facility.
It's roughly nine feet tall, nine feet wide and on the order of 30 to
35 feet long so we have a pretty good area in which the play with the
So this is what I would call the X axis right along here.
And then the Y axis would be moving along this little rail here.
Called a gantry.
There is two degrees of freedom there.
A V axis would be moving up and down.
You have three translational degrees of freedom.
Go to the next slide.
This gives you an idea of how the racks look in it.
You saw in the video clips the racks with the circular black disks.
We built that so that when the PSA vision system is looking around at
its environment it sees something that looks somewhat like a Space Station.
The Space Station doesn't have the disk.
We're using it to test the system but it looks different than a room.
And so on the next slide you can see a little blowup.
This is a blowup of the Y axis again.
There is a little trolley that rides on here, little wheels that allow
it to move back and forth through the Y axis motion.
On the next slide you can see what we had to create to do the Z axis.
I think it speaks for itself.
A pretty complicated mechanism that involves the ball, the PSA, to move
up and down, which is the axis, while it is also moving in the Y axis
which is trolleying back and forth.
While it is also moving in the X axis.
All three things can happen at once or separately, it doesn't matter.
You want the PSA to go about its business not realizing it is attached
That would be ideal.
There are other things in here that make it not perfect but we're always
trying to get it closer and closer to what it would really be like on
>> You have to use a lot of problem solving and trying different
angles of things.
If your first idea doesn't work you have to try a different approach just
as you talked about your different designs before you came to this one.
>> First you think about ideas.
You think about ideas that might work and then you eliminate some of them
and get smarter and smarter.
When you think you have the per ferkt -- perfect idea.
Why don't we go ahead and rip this out and put in this new thing in here
and it always gets more complicated in order to get it to work better.
>> I'm sure you've had some frustrating times where you thought
something was going to work and you had to let go of a certain idea?
>> Very much so.
I think we have one more slide that shows the mechanism in a little better
And now I want to show the PSA actually operating in the crane.
You have seen a little bit of it.
This is the video of the PSA driving -- sorry, first, got some video here
of the actual device.
You saw that on top.
This was the mechanism you saw in the pictures before.
You see Mike putting his hand over it and might be able to make out a
red dot on his hand.
That's a laser mounted up above shooting down to a sensor below which
is detecting what the PSA is trying to do and moving the crane accordingly.
And so that laser is, of course, not hurting his hand.
It's like a laser pointer or something.
If he were to grab the ball, the crane would know how to follow it.
It's the trick of making the crane work.
The crane is a very dumb thing.
A very simple mechanical device.
But when you put the sensors on it, the sensors allow the crane to see,
To see what the PSA is doing and then take action in order to fool the
PSA into believing it's really in microgravity.
Now we'll go ahead and show the video of the PSA arriving at the test
It's powering the fan.
Kind of turning left and now it's powering forward while turning.
Straightening itself out and heading to the back.
So it's really flying as it would on the station or on the spacecraft.
And the crane is just following its movements as it's supposed to.
So that is how we chose -- we're not done.
There are little things about it that could be better and so to give you
an idea of how long this took as well, the crane, so far has taken us
two years of work in a team of four people of different expertise squeezing
every last bit of capability.
>> The students can appreciate what they can do in a few weeks you
have years to work on and are still working on it.
It is still a process.
I want to thank you to talk to us about.
We have Linda over here who has been kind of reading these questions and
I think she'll let us know what some of you have to ask.
We're delighted to have the Caroline Robbins community school from Canada
with us today and several questions from that classroom.
Why do the astronauts need the PSA?
>> Good question.
The PSA can have a lot of different capabilities.
There is too many to name here.
The principal ones are the PSA has a lot of sensors on it.
The sensors are things that measure how much oxygen is on the spacecraft.
How much carbon die ox -- dioxide, pressure and humidity.
All those things that matter when you have humans trying to live in space.
And so if something were to go wrong with the spacecraft systems, the
PSA could be deployed to fly out there, maybe while the astronauts are
in a safe area and can figure out whether it's safe or not.
The PSA also has a very large screen and on this screen all sorts of data
can be provided.
It could be used for videoconference.
Let's say I'm an astronaut working on an experiment on the station.
PSA is perhaps hovering right here next to me so I'm working away and
I look up to PSA and what I see in the image here is the scientist on
The scientist who is in charge of this plant experiment.
I see her face right here and I speak with her and I say so, what would
you like to see?
The speaker is on the PSA.
I can hear her voice so she says you know that plant over there three
rows back and two over?
Can you turn up its leaves so I can see what is happening underneath it?
I clip it up.
PSA, because it has cameras, can look at the leaves which is transmitting
video back to her on Earth and almost as if she is right there and this
is an astronaut assistant.
Other reasons for safety reasons that the PSA could be used as well.
Here is a question from Logan.
I'm going to combine them.
He says how do you power the PSA in space and what is the power source?
I think they're combined enough to -- not sure if he means electric power
or how you get it to move.
>> I think he's talking about one of each.
I think he's talking about how do you power it, a battery or--
>> I'll address both.
What we have in the back of the PSA here is a little patch here.
When you take this off, this isn't a working version, but you take this
hatch off and inside are batteries.
We have rechargeable batteries.
The idea would be when the PSA is docked in its location in the spacecraft
it is always charging the batteries like your cordless drill or remote
Then when it takes off, releases and takes off to go about doing work
it is running off of electricity from the batteries.
That's how it's powered.
From the standpoint of how it moves if the question is how you drive or
power around, what we have in the video that you saw on the screen are
You know, fans like your blow drier fan or something like that.
That actually blow air in directions that the computer inside the PSA
And that's how it steers about.
In the case of this PSA which is going to be the next generation PSA there
aren't fans but blowers, big round blowers, one on the top, one on the
It blows air out through these vents here.
So from the degrees of freedom point of view like we were talking about
before, if I blow air out the back on top and bottom I will move this
If I blow it out the front I'll move this way.
That's X axis.
If I blow it up the top on one and different on the bottom I can get it
That would be a pitch axis.
That's how we go about getting it to move.
>> James wants to know how early in the design process do you start
testing your PSA in a microgravity setting?
>> If you already have a good microgravity testbed which we do now,
we test it as soon as you can.
Usually you don't really know what you need for a while.
So it's actually a very insightful question.
I would say when you're first working with a robot, it probably won't
work very well at first, it might be good to only work with a few degrees
If you have all six available it may be so confusing what is going on
that you won't be able to figure it out and tune the system to work right.
Maybe something like a granite table or the helium balloon idea or something
like that would be a good first step.
There are only so many things you can do.
When you get it nailed you work to a granite table and a testbed like
our microgravity test facility.
Sandy is asking, I think you may have answered this already.
But will you be testing the PSA on the plane?
>> Yes, we will.
I think we'll learn a lot more in this test facility you see video of
because we have a lot more time, we're familiar with it.
That's where 90% of our knowledge is going to come from.
Things that end up going to flight, things that actually end up going
into space go through this KC135 test that is a validation that you're
ready, this robot is really working.
We'll go with the KC135 after we get done with the testing we're doing
>> Sounds like fun.
A question from Chelsea.
She says how can the cameras on the PSA can connect with NASA on earth.
>> Let me show you where the cameras are.
Two cameras here, a camera on each side.
And then there are two cameras in the back.
The reason we have two cameras on the front and back.
It works like your eyes.
You're able to get depth perception and how far away you are from things.
We have that in the front and back.
The images that come off these cameras are sent -- like a remote control
toy transmitted through the air.
Those images are sent to a computer-on station.
The PSA doesn't have a strong enough capability to broadcast back to Earth.
But the Space Station does and spacecraft in general do.
This has to communicate 10 to 20 feet away to the antenna on the station
and then the station relays that information to Earth.
The same thing happens in the other direction.
We have another question here from Logan.
He wants to know, is there any working PSA already made and if so, how
>> Working, boy, you have to define that one right.
What you have seen in the crane is a real working PSA.
There is no gimmick or monkey business.
That's really flying in the crane facility.
Is there a working PSA on any spacecraft right now, the answer is no,
we haven't gotten that far yet.
One of the things that you have to worry about, even if the thing were
working perfectly, everything was working the way we wanted and passed
KC135 test, everything is great, there is a limitation of what you can
bring up on stations.
So the plastic that this is made out of has to pass certain tests before
it is allowed to be up there.
The metal parts, the energy.
Batteries can cause harm to the astronauts.
Could parts come flying out of these things.
What about a gummy bear or something floating into the air gets sucked
What will happen to the robot.
These are practical issues before you're allowed to bring any piece of
equipment onto the station.
Once we get to the point where the robot is working well and we're trying
to do that right now, then we go through what is called a quality -- qualification
to get it on the spacecraft.
That's all in front of us.
>> Alley wants to know will you be developing other ways of testing
the PSA or is this the one?
>> Good question.
What we found is that the crane facility that you see, what we call the
microgravity test facility, works very well for the constrained environment.
It's in a room and it fills out every wall in there.
We can't make it any bigger.
What that means is you saw the yellow cords coming down.
Those work like a swing.
We don't want them to work like the swing because that's the nature of
it because we have a ceiling to do with.
We are thinking about going to a bigger room.
Not because we want the space to be bigger.
It will be the same size but if we had a lot more head room we could design
a system that would work better than this one and it wouldn't have some
of the problems we're having to deal with.
Like the PSA wanting to swing back and forth because it's hanging from
If we had it hanging from a rigid piece of steel there would be no swinging
but we would be wiping the ceiling in this room.
By moving to a different facility we can make the design better.
We like what we have.
I don't think there is a better thing out there that we can conceive right
A lot of questions coming in all of a sudden.
Jim wants to know, did you have to worry about the noise the PSA would
produce when designing it?
How loud are the fans?
>> You picked up on no sound on any of the videos.
There actually is sound on the videos you just didn't hear it on purpose
because these things are loud.
These things are too loud.
And so you have to think about when you're designing the PSA what should
I be attacking first?
What are the first problems?
In our case the first problem is how do you fit everything in something
That's a big problem.
The second one is how do you get it to reliably move around?
We're attacking the big problems first.
Secondary problems are things like sound, quite Frankly.
If it is so loud that the astronauts are up there are annoyed or having
to yell at each other because the PSA is so loud, that won't be something
they want to use.
So in the next versions of the PSA we'll be trying to do two things.
We'll be trying to shrink it, which is very difficult to do, and we're
going to be trying to create propulsion means, means for it to drive around
that are quieter.
That's a big problem because to make things quieter you lose power.
You lose power the PSA can't move as fast and it can't move for as long.
You use up the batteries.
That's a tough one.
To answer your question right now the PSA is probably not quite as loud
as a hair dryer but it's pretty loud.
>> I want to let you know out there, some of you who are sending
in questions, we'll try to cover whatever we don't cover here in this
hour during the next hour's webcast.
So join us then.
I'm going to take one last question.
Curtis wants to know, what would happen if an astronaut was working with
water and a PSA got some on it?
In the video you showed us the water was in its sphere.
Could this happen?
>> Let's answer the question first.
If water were to get on the PSA that would not be a problem.
It is a plastic exterior, it would not care about water on its exterior.
The concern I would have is if there are little bubbles of water or anything
for that matter, not just water, hair is a big issue.
If the PSA were moving and sucking in air through the inlet ports and
trying to blow it out through these, there is a lot of problems that could
When the astronauts were showing the water bubbles, gummy bears what they
were doing was demonstrating what microgravity looks like.
These aren't toys out all the time and something the PSA will have to
In all seriousness the PSA will have to avoid floating tools, hair, I
said that before.
Hair is a big thing.
If someone has long hair and it is floating all over the place as microgravity
would be inclined to have it do, what does that mean for the PSA?
So that's not the astronaut's problem but our problem.
We have to come up with means for screening it to try to keep out those
>> OK, great.
I think we've come to the end of the hour so I'll turn it back to you,
>> First of all I want to thank all the talented students and teachers
out there who participated in this challenge and thank you to NASA engineer
Dan Andrews and PSA for sharing your work with us.
Our final video we'll take a look at the PSA and how it might work to
solve a problem on the International Space Station.
Thanks for joining us.
>> Copy that.
Stand by, payload.
There is a temperature increase of unknown origin.
Food schedules are set.
We recommending deploying PSA to investigate.
>> Top loading PSA initiallyization sequence.
Payload, PSA confirmed appointments.
Performing Y axis rotating.
Life science payload rack one, Oscar three.
>> Payload, we confirm PSA position at life science payload racks
one Oscar three.
Infrared sensors initializeed.
Beginning infrared sweep.
>> Copy that.
We've got a real good signal here.
It's from the adjacent payload rack.
>> Powering up ventilation fan to dissipate the excess heat.
>> Copy that.
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Responsible NASA Official: Tom Clauson
NASA Ames Research Center, Moffett Field, California, USA