Science series. Jem witnesses the power of rockets with the Bloodhound land speed record project. Yan re-enacts an Ancient Greek experiment to measure the earth's circumference.
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On tonight's programme:
Jem witnesses the awesome power of rockets
when he hooks up with the team behind a 1,000-mile-per-hour car.
And the one they're putting on Bloodhound
is about 1,000 times the thrust.
And Dallas looks into the future in the search for a robot he can call his own.
These aren't just remote-controlled toy robots. These are actually autonomous.
That's Bang Goes The Theory,
revealing your world with a bang.
Hello and welcome. We're going to start with the Bloodhound project,
which is looking to set
a new land speed record, a staggering 1,000 mph.
To do that, they're going to need a rocket, a very big rocket.
So what does a rocket give you,
that a jet engine doesn't?
This is a jet engine. It may look smaller than the ones that take you on holiday
but it still gives one hell of a shove.
Put it this way, they'd lift a good-sized dog off the ground.
Jet engines, like most engines, work by sucking air in,
mixing it with fuel and creating a big fire inside.
All this engineering that you see, it's just there to control that fire
and turn the heat into thrust.
Because you've got so much control of the fuel and the air going in,
you've got a lot of control over the trust.
They're also very reliable and very durable.
And very loud.
This little fella here...
is a rocket. It may look a little small and simple compared with the chunky jet engine
and its elaborate fuel system,
and it may seem a little unfair to pit them head to head, thrust for thrust,
but that's exactly what I'm going to do.
I've mounted these up, both exactly the same distance
from the centre of the seat of this spinny chair.
The plan is, I'm going to fire up the jet engine to full thrust.
It's then going to power itself up against this stop.
When it's at full power, I'm then going to switch on the rocket
and see if the rocket can out-thrust the jet
and push itself in that direction.
'Here goes. Throttle up on the jet.'
'It's a slow build-up of thrust. Needs a little time to get going.'
'Just enough power now to move the arm around.'
'Let it build up to full thrust.'
HIGHER PITCHED REVVING
'OK, now THAT would launch your dog.'
'Time to arm that tiny rocket.'
'T minus five.'
'Look at that.
'For a few beautiful seconds, that little rocket totally outdoes the jet.
'And then, it's all over.'
and the one they're putting on Bloodhound
is about 1,000 times the thrust.
So how did a little rocket like that
outperform a hefty jet engine like the one over there?
Well, it's because the inferno going on in there
is far, far more ferocious than the burn inside that jet engine,
which means more power in a smaller package
and if you attach a smaller package to your car, you're going to get less drag
and potentially a higher top speed.
But how does this get that far more intense inferno inside?
Well, that is pretty much just down to oxygen.
Any fire is generally just a chemical reaction between a fuel and oxygen.
And it's that reaction that releases all the heat.
It doesn't really matter whether that fuel is rocket fuel,
jet fuel, petrol or the charcoal on my barbecue.
The principle's still the same.
The better the oxygen supply, the faster it's going to burn.
Now at the moment, this barbecue's burning all right by virtue of
air drifting in from its surroundings, supplying the coals with oxygen.
But say I wanted it to burn faster, say I was feeling hungry and I wanted a quicker burger.
I need to give it more oxygen.
-So I can
-blow it in.
HE PUFFS HARDER
Which does all right.
Or maybe step things up with a bit of compressed air.
That's forcing my fuel to burn a bit quicker.
But I'm starving.
I want to get this thing burning super-quick.
I need the richest oxygen supply I can, and air just doesn't cut it.
It's only 21% oxygen.
So I'm thinking, what if I added liquid oxygen?
That's gone off like a rocket.
'And that's because it's burning like a rocket.'
'Rather than getting its oxygen from the air,
'a rocket carries its own, more potent supply.'
Which means there's more heat, there's more power,
which is fantastic for thrust, but I believe,
not quite so good for cooking.
Very good interesting barbecue technique, unconventional.
But I liked it, I liked it. I visited the Bloodhound team last series.
It is an awesome project, very, very exciting.
A little audacious to say the least. The thing is, once you introduce a rocket to a project,
you might solve a bunch of problems but also open one massive can of worms.
As they say, rocket science is a little complicated.
Later in the show, I'm going to visit them to find out just how difficult.
'And follow the links from Slash Bang to a veritable treasure trove
'of facts about oxygen and all the other elements
'at the Open University's all-new interactive periodic table.'
Good. Well, speaking of complicated things, it's time for another Dr Yan conundrum.
-Ready for this one? It's a little bit tough.
OK, when does two equal one, or to put it another way, when does one equal two?
-It's too cryptic. Did you get that at home? I think that's too cryptic.
Let me give you a clue. Think algebra, think equations, put your maths hats on.
-Do I have to?
-I can't think.
-I can see where you might be going.
-If you're a little bit stumped,
check out the full answer on Slash Bang as always.
If we're in to difficult questions, try this one...
If I were to ask you to measure the entire circumference of the Earth, how would you do it?
Tape measure, run really fast, no, I'm sorry.
A little impractical.
But believe it or not, 240 BC,
a Greek fella figured out how to do it with just two sticks.
So our man Dr Yan has tried to recreate that incredible experiment,
with a tiny bit of help from me.
It might surprise you to know this,
but the ancient Greeks didn't think that the Earth was flat.
They thought it was round and not only that,
but Eratosthenes managed to calculate
the circumference of the entire Earth simply by measuring
the length of a shadow cast by a stick
when the sun was at its highest in the sky.
That's just incredible. Let me show you how he did it.
Now, Bang HQ is down there in Brighton and if you go due north from there
until you hit the sea, you end up here, in Mappleton near Hull.
And if the Earth were flat, then the length of a shadow
cast by a stick would be the same in both places.
But Eratosthenes realised that because the Earth is curved,
then the angle of the sun in the sky
and the length of the shadow, would be different in different places.
It occurred to Eratosthenes
that if he could measure the angle of the sun, using shadows,
in two places on Earth, then he could use that to work out how many degrees
around the curve of the Earth the two places were from each other.
Eratosthenes made one of those measurements in his home town of Alexandria.
But how did he make the other one?
Well, it turns out he'd heard of a strange phenomenon
in a town called Syene in the south of Egypt.
At noon on the summer solstice, a vertical well was lit all the way to the bottom,
meaning the sun had to be directly overhead at 90 degrees.
Eratosthenes was able to calculate the angle between the two places
using another ancient Greek speciality, geometry, like this.
Imagine this is the Earth...
..and this here is Syene,
where on the summer solstice, the sun's rays hit at exactly 90 degrees.
Now this is Alexandria, where he calculated
that the angle of the sun's rays was 83 degrees.
What Eratosthenes wanted to do is calculate this:
the angle in the centre of the Earth between the two places.
And because the sun's rays are parallel,
then this angle here must be the same as this angle here.
Right. Now time to go and calculate my angles.
It's local noon, so the sun's as high as it's going to get.
And all I need to do is to measure the length of the shadow of this stick.
Right, there we go.
I reckon that's, er, 105 centimetres.
Now, I can't be in two places at once but luckily,
Jem is down in Brighton at Bang HQ. All I need to do is give him a ring
and he should have a measurement for me.
-Hi, Jem, can you give me the length of the shadow?
Just a sec.
I'm looking at 936, I would say.
-93.6 centimetres. Brilliant, thank you very much.
-Great. Cheers, Yan.
My stick was 170 centimetres high
and my shadow was 105 centimetres long.
So the angle of the sun was...
For Jem, well,
his shadow was 93.6 centimetres.
So Jem's angle is, well, 61 degrees.
That means that the angle at the centre of the Earth between Jem in Brighton and me here in Mappleton
is 61 minus 58, which is three degrees.
How does that help work out the circumference of the Earth? Let me demonstrate with this pizza.
Now if the angle in the centre here is three degrees -
that's a pretty stingy slice of pizza,
then I can fit 120 of those
into the whole pizza, because three times 120 is 360.
And that means that the distance all the way round the edge is
just the distance along the edge of one of these slices, times 120.
The distance from here to Brighton, as the crow flies, is about 330 km,
so the circumference of the earth must be 330 times 120.
That comes to 39,600 kilometres. And Eratosthenes - well,
he calculated the circumference of the earth at 39,690 kilometres.
How about the real figure?
Well, modern satellite measurements tell us that
the circumference of the earth around the poles is 40,008 kilometres.
So I did really well. And Eratosthenes didn't do too badly either,
but he didn't get a pizza for it and I do.
So that's great.
Now when I was a kid, you couldn't move for predictions
of exciting robots that would pander to our every whim,
and obviously nowadays we live alongside robots in our factories,
in our electrical devices, even in our traffic lights, but somehow,
I can't help but feel a little disappointed.
But the fully autonomous robot companion of my dreams?
So why are we still waiting?
I've come to Edinburgh University's robot lab to find out
how close we are with the latest tech.
When I was a kid, the idea was that definitely by now
we would have robots that could think for themselves,
they'd be able to mix the perfect martini and make tea
and would be able to work with us as humans on our terms.
It just seems that we're not even nearly there,
or there's been something wrong, there's something holding this up.
You're right. It hasn't happened, because people probably underestimated
the amount of things that you need to consider
when doing apparently simple tasks. Think about an autonomous system,
for example crossing a road, then it has to make decisions
on its own, it has to sense the state of the environment.
So it's a lot more complex.
A decent robot needs to be capable of performing really complicated tasks,
like these little fellows, who have mastered the beautiful game.
Let me check - these aren't remote-control toy robots,
these are actually autonomous. Can I say they're autonomous?
They are autonomous in the sense that they've got its own sensors,
so it's got cameras, it's got wireless, infra red sensors,
and they've got some touch sensors.
That one's just fouled him. He just sort of kicked him in the shin.
That's a robot red card.
The basic behaviour's built in, like go for the ball,
once it reaches the target, aim and kick,
and the goalkeeper has a basic task of saving it,
so these typical behaviours are then controlled
with a higher level artificial intelligence,
to figure out which of the behaviours to trigger when,
so that it can achieve the overall goal of trying to defend or score a goal.
To play football these guys must be pretty clever, but recreating
anything like human intelligence is unbelievably complicated.
Even so, his team are making progress.
The robot has a webcam for its eyes, so it can look at the state
of the game, and figure out the moves you've played and what it has done.
The most important component
is the AI or the planning behind it,
which basically tries to figure out the strategy that you are playing
and first of all try to defend itself and maybe try and beat you.
I can see what it's trying to do. I can see exactly how I'm going to lose as well.
Oh, it won.
Yeah. Yeah, it won.
It won. Where's the hammer?
But it's hardly the kind of personal robot I've got in mind.
I mean, that is incredible, just seeing the strategy there,
and it can see and knows where to put things,
but how are we going to put this together and create my ultimate robot?
I think what we've seen today is that there are bits and pieces
which are brilliant, but actually what you need for something like a robot butler
would be to first of all put all these things together,
into a very fast, reactive robust system, but on top of that, have the robot... give the robot
the ability to learn and adapt and change, just like you and me do.
And this might be the answer.
Although it doesn't look like quite like I expected,
this is the closest thing yet to a proper independent robot.
This machine can drive, navigate, and avoid obstacles, all without any human involvement.
Off we go. Very smooth.
Sensing, planning and reacting,
all critical for a real independent thinking robot,
and they're are all mastered by this vehicle.
So just how intelligent is this thing?
It's pretty good, you know. You can even tell it senses
when you're going up a gradient.
You can sense it being aware of where it is,
and the kind of terrain it's driving on,
as we go down a - ooh, blimey!
See if it manages this pothole.
I'm now rather disconcertingly heading towards
two concrete objects in the middle of the road.
Very cleverly, the car's spotted them and it's driving round them.
Look at that. It's amazing.
All I have to do is sort of sit here. On board there are a whole host of sensors.
You might be able to see on the roof, that thing spinning around.
That's a lidar. That sees the world using laser ranging.
There's also radar on board, there's also various cameras, GPS,
and all that information about the outside world gets thrown back
to a big number-crunching computer in the back,
which makes the decisions, and puts it all forward to the mechanics of the actual car.
I've got a screen here that gives me all the information coming from the various sensors,
so I can check the software is all running correctly,
that the lidar is...lidaring.
OK, we are going slightly off-piste here.
Blimey! It really does have a mind of its own.
This incredible machine marks a great leap forward
in the development of autonomous robots
but the driving force behind it isn't the need for domestic robots.
It's the need for robots on the battlefield, where very soon, machines like this
will be doing all sorts of tasks, from reconnaissance to bomb disposal.
So, something like this is really a test bed for the latest autonomous technology,
a chance to put it through its paces in a real-world situation.
In one sense it's great, because you have the potential
to save lives, but I can't help but wonder where else this could lead.
Now, there are no plans to fit weapons to this vehicle,
but that wouldn't be difficult in theory, and then what?
Instead of my dream robot companion,
you could imagine its evil nemesis - a Terminator, a Dalek?
I've come to meet robot ethicist Blay Whitby, to see what he thinks
about living, working and maybe fighting alongside our mechanical cousins.
In terms of autonomous robots of the battlefield, we're sort of seeing already
flying drones, unmanned drones that can get somewhere on their own,
but don't pull the trigger on their own - there's still a human in the loop.
At present, there's a human being's finger on the trigger.
But in the relatively near future we're going to move to
a situation where these things can autonomously decide to kill.
We are talking about things with very limited cognitive capacity?
Incredibly limited cognitive capacity. Well below insect level.
At present, we don't know how to make robots that are as clever as ants.
-So these... so not even as clever as an ant?
-Not even as clever as an ant.
You have got to realise how limited current technology is.
These things don't have any ethical sensibility,
they don't have any emotions, they don't have moral values.
In fact, we haven't been able to programme any common sense into them.
A lot of autonomous technology seems to come from the military.
But as it gradually filters down into everyday life,
are we going to face similar moral and ethical and social questions?
Everybody is meeting smarter and smarter technology every day. That is going to continue.
Very close to market technology is that of smart homes,
which are like an automated apartment which will look after old people.
Maybe someone would decline in cognitive capabilities. Maybe someone with a brain disorder.
It will decide what they eat, whether or not they're eating healthily,
and summon human assistance if they need it.
The problem is, there's no code of practice for building these things.
There is no public discussion about what's acceptable and what's not.
They're simply going to be built. The time for this discussion is now.
-Very quickly, all-time favourite robot?
-R2-D2, without a doubt.
-For me, it's my washing machine.
Now moving on, I go rocket testing with the Bloodhound team.
I'm heading to the countryside to meet Daniel Jubb,
Bloodhound's chief rocket engineer.
It's taken them several years to design a rocket
capable of powering Bloodhound to an incredible 1,000 miles an hour.
And today, we're putting their latest model to the test.
'Yeah, this is definitely rocket science.'
It's, eh, it's a little big bigger than the rockets I've built, but broadly similar.
Indeed. Exactly the same principle.
How many rockets have you tested so far?
We've conducted several firings of the six-inch hybrid chamber.
It's an important development tool
for the full-size 18-inch chamber for Bloodhound.
We have learnt from the successful firings and the two failures. One burnt a hole in the motor case.
The other sent the motor case and nozzle assembly over 300 feet down the desert.
-Right. So we'll be careful then.
'Daniel's rocket is a hybrid rocket.'
It means it's got a solid fuel, into which is pumped a liquid oxidiser.
The fuel he's using is a kind of rubber.
It's similar to the rubber used in the cushioning of training shoes. Just a bit faster.
Right, so in comes the oxidiser. The first thing it hits is this catalyst pack.
Now that makes it split into steam and oxygen.
The oxygen, under high temperature, hits this rubber and starts burning.
At a couple of thousand degrees, this gas is expanding rapidly.
As it expands through this nozzle,
it gets accelerated to supersonic speeds.
So what you end up with is a supersonic plasma going in that direction.
Getting maximum power from the rocket isn't as simple as pumping in as much oxidiser as possible.
It's critical that the fuel and oxidiser mix in exactly the right proportions.
These are going to be my rockets.
I'm going to use plain air as my oxidiser.
I'm going to use acetylene as my fuel.
You might think, a stack of fuel, surely that's the best way to go?
You might think it's best to have loads of oxidiser and not so much fuel.
So this one...
Or you might want to try some rocket science, which means in my bottle that's about 77 millilitres.
My three rockets are now set.
They've got their fuel/oxidiser ratio. This one stacks of fuel.
This one stacks of oxidiser.
This one, hopefully, the scientifically correct formula.
Time to retire... and fire.
Three, two, one...
Look at that!
Just the right amount of fuel/oxidiser mix.
It is a massive explosion.
And that is what you want in a rocket
if you're going to get to 1,000 miles an hour.
Working out how to achieve this perfect mix has been the main challenge for Daniel's team.
Firing up a rocket of this size is seriously dangerous.
I guess we get into these?
So it's a real privilege to be taking part in this test.
For the Bloodhound rocket,
our oxygen source is something called high test peroxide, or HTP.
But although it's fairly stable and non-toxic,
it still needs to be handled carefully.
What we're doing is sucking the hydrogen peroxide into this tank.
Once it's full...
we then seal it off. The next stage,
which can only be done once we're clear of the building,
is it gets pressurised by those nitrogen cylinders there.
The pressure means there's probably 50 tonnes of force
trying to burst the top and bottom off that tank.
'After helping Daniel to load the HTP oxidiser, we slowly open the valve...'
..before retreating to the safety of the monitoring bunker.
The rocket's bolted firmly in place.
We don't want it flying anywhere in this test.
OK, are we ready?
To succeed, we want spontaneous ignition. 100% burn in around 10 seconds...
Close the vent.
The vent is closed.
..producing at least 2,000 pounds of thrust.
Pressurise the tank.
OK, we're about 15 seconds away.
Start the countdown.
Will Daniel's calculations prove right?
Nine, eight, seven, six, five...
Valve cracked. Crack more.
Internal temperature, around 2,500 degrees.
Internal pressure, 550 PSI. Maximum thrust, 2,500 pounds.
Success! Nothing burst! Nothing like... oh! I'm relieved.
The rocket has performed perfectly, taking the Bloodhound team one step closer
to their dream of driving at 1,000 miles an hour.
-That was epic!
-Blimey. I'll tell you what, I wonder if Andy Green,
who's driving the Bloodhound car, was watching that.
He might have a little collywobble. You know what I mean?
I really wouldn't blame him if he was a bit...
That was just a third-scale model. I was three bunkers away, and it still felt a bit much.
For the real thing, OK, the real thing, just pumping in the oxidiser
will be a pump out of a cruise missile.
And it's hosing in oxidiser because it's powered by a V8 Cosworth Formula One engine.
The rocket that's going to go on that 1,000 mph car is so big,
that when it's tested in a few weeks, it will be the biggest rocket test in the UK for 20 years.
And it is all on our website.
It's a truly awesome project. OK, that is it for this week.
Next week, I'm looking at something that bothers a lot of people, and that's forgetting things.
You know when you walk into a room and can't remember why you're there?
-It happens to me every day.
-It drives me round the bend. I'm looking at how memory works,
and what you can do to make sure you never lose your car keys again.
Nice one. And I'm going to be looking into stem cell research. Still a controversial subject.
But its potential for use in organ repair and whole-organ transplants
has moved on in leaps and bounds.
And our dear Dr Yan? He has finally cracked.
He'll be inflicting pain on people. You've been warned.
You really have. We will see you next week. Bye-bye!
Subtitles by Red Bee Media Ltd
E-mail [email protected]
Jem witnesses the awesome power of rockets with the Bloodhound land speed record project, Yan re-enacts an Ancient Greek experiment to measure the earth's circumference with a couple of sticks, and Dallas goes in search of a robot to call his own.