Episode 3 Bang Goes the Theory


Episode 3

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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Transcript


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On tonight's programme:

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Jem witnesses the awesome power of rockets

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when he hooks up with the team behind a 1,000-mile-per-hour car.

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That's insane!

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And the one they're putting on Bloodhound

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is about 1,000 times the thrust.

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And Dallas looks into the future in the search for a robot he can call his own.

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These aren't just remote-controlled toy robots. These are actually autonomous.

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That's Bang Goes The Theory,

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revealing your world with a bang.

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Hello and welcome. We're going to start with the Bloodhound project,

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which is looking to set

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a new land speed record, a staggering 1,000 mph.

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To do that, they're going to need a rocket, a very big rocket.

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So what does a rocket give you,

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that a jet engine doesn't?

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This is a jet engine. It may look smaller than the ones that take you on holiday

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but it still gives one hell of a shove.

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Put it this way, they'd lift a good-sized dog off the ground.

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Jet engines, like most engines, work by sucking air in,

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mixing it with fuel and creating a big fire inside.

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All this engineering that you see, it's just there to control that fire

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and turn the heat into thrust.

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Because you've got so much control of the fuel and the air going in,

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you've got a lot of control over the trust.

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They're also very reliable and very durable.

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And very loud.

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This little fella here...

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is a rocket. It may look a little small and simple compared with the chunky jet engine

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and its elaborate fuel system,

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and it may seem a little unfair to pit them head to head, thrust for thrust,

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but that's exactly what I'm going to do.

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I've mounted these up, both exactly the same distance

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from the centre of the seat of this spinny chair.

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The plan is, I'm going to fire up the jet engine to full thrust.

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It's then going to power itself up against this stop.

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When it's at full power, I'm then going to switch on the rocket

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and see if the rocket can out-thrust the jet

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and push itself in that direction.

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'Here goes. Throttle up on the jet.'

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ENGINE STARTING

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'It's a slow build-up of thrust. Needs a little time to get going.'

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ENGINE REVVING

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'Just enough power now to move the arm around.'

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'Let it build up to full thrust.'

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HIGHER PITCHED REVVING

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'OK, now THAT would launch your dog.'

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'Time to arm that tiny rocket.'

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'T minus five.'

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'Look at that.

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'For a few beautiful seconds, that little rocket totally outdoes the jet.

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'And then, it's all over.'

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ENGINE EXPLODES

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That's insane.

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and the one they're putting on Bloodhound

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is about 1,000 times the thrust.

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So how did a little rocket like that

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outperform a hefty jet engine like the one over there?

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Well, it's because the inferno going on in there

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is far, far more ferocious than the burn inside that jet engine,

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which means more power in a smaller package

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and if you attach a smaller package to your car, you're going to get less drag

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and potentially a higher top speed.

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But how does this get that far more intense inferno inside?

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Well, that is pretty much just down to oxygen.

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Any fire is generally just a chemical reaction between a fuel and oxygen.

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And it's that reaction that releases all the heat.

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It doesn't really matter whether that fuel is rocket fuel,

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jet fuel, petrol or the charcoal on my barbecue.

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The principle's still the same.

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The better the oxygen supply, the faster it's going to burn.

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Now at the moment, this barbecue's burning all right by virtue of

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air drifting in from its surroundings, supplying the coals with oxygen.

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But say I wanted it to burn faster, say I was feeling hungry and I wanted a quicker burger.

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I need to give it more oxygen.

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-So I can

-(HE PUFFS)

-blow it in.

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HE PUFFS HARDER

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Which does all right.

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Or maybe step things up with a bit of compressed air.

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HISSING

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That's forcing my fuel to burn a bit quicker.

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But I'm starving.

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I want to get this thing burning super-quick.

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I need the richest oxygen supply I can, and air just doesn't cut it.

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It's only 21% oxygen.

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So I'm thinking, what if I added liquid oxygen?

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That's gone off like a rocket.

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'And that's because it's burning like a rocket.'

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'Rather than getting its oxygen from the air,

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'a rocket carries its own, more potent supply.'

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Which means there's more heat, there's more power,

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which is fantastic for thrust, but I believe,

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not quite so good for cooking.

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Very good interesting barbecue technique, unconventional.

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But I liked it, I liked it. I visited the Bloodhound team last series.

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It is an awesome project, very, very exciting.

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A little audacious to say the least. The thing is, once you introduce a rocket to a project,

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you might solve a bunch of problems but also open one massive can of worms.

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As they say, rocket science is a little complicated.

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Later in the show, I'm going to visit them to find out just how difficult.

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'And follow the links from Slash Bang to a veritable treasure trove

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'of facts about oxygen and all the other elements

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'at the Open University's all-new interactive periodic table.'

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Good. Well, speaking of complicated things, it's time for another Dr Yan conundrum.

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-Ready for this one? It's a little bit tough.

-Hit me.

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OK, when does two equal one, or to put it another way, when does one equal two?

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-Any ideas?

-It's too cryptic. Did you get that at home? I think that's too cryptic.

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Let me give you a clue. Think algebra, think equations, put your maths hats on.

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-Do I have to?

-Yes.

-I can't think.

-No ideas?

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-I can see where you might be going.

-If you're a little bit stumped,

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check out the full answer on Slash Bang as always.

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If we're in to difficult questions, try this one...

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If I were to ask you to measure the entire circumference of the Earth, how would you do it?

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Tape measure, run really fast, no, I'm sorry.

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A little impractical.

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But believe it or not, 240 BC,

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a Greek fella figured out how to do it with just two sticks.

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So our man Dr Yan has tried to recreate that incredible experiment,

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with a tiny bit of help from me.

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It might surprise you to know this,

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but the ancient Greeks didn't think that the Earth was flat.

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They thought it was round and not only that,

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but Eratosthenes managed to calculate

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the circumference of the entire Earth simply by measuring

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the length of a shadow cast by a stick

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when the sun was at its highest in the sky.

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That's just incredible. Let me show you how he did it.

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Now, Bang HQ is down there in Brighton and if you go due north from there

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until you hit the sea, you end up here, in Mappleton near Hull.

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And if the Earth were flat, then the length of a shadow

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cast by a stick would be the same in both places.

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But Eratosthenes realised that because the Earth is curved,

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then the angle of the sun in the sky

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and the length of the shadow, would be different in different places.

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It occurred to Eratosthenes

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that if he could measure the angle of the sun, using shadows,

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in two places on Earth, then he could use that to work out how many degrees

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around the curve of the Earth the two places were from each other.

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Eratosthenes made one of those measurements in his home town of Alexandria.

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But how did he make the other one?

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Well, it turns out he'd heard of a strange phenomenon

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in a town called Syene in the south of Egypt.

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At noon on the summer solstice, a vertical well was lit all the way to the bottom,

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meaning the sun had to be directly overhead at 90 degrees.

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Eratosthenes was able to calculate the angle between the two places

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using another ancient Greek speciality, geometry, like this.

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Imagine this is the Earth...

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..and this here is Syene,

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where on the summer solstice, the sun's rays hit at exactly 90 degrees.

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Now this is Alexandria, where he calculated

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that the angle of the sun's rays was 83 degrees.

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What Eratosthenes wanted to do is calculate this:

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the angle in the centre of the Earth between the two places.

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And because the sun's rays are parallel,

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then this angle here must be the same as this angle here.

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Right. Now time to go and calculate my angles.

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170 centimetres.

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It's local noon, so the sun's as high as it's going to get.

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And all I need to do is to measure the length of the shadow of this stick.

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Right, there we go.

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I reckon that's, er, 105 centimetres.

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Now, I can't be in two places at once but luckily,

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Jem is down in Brighton at Bang HQ. All I need to do is give him a ring

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and he should have a measurement for me.

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-Hey, Yan.

-Hi, Jem, can you give me the length of the shadow?

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Just a sec.

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I'm looking at 936, I would say.

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-93.6 centimetres. Brilliant, thank you very much.

-Great. Cheers, Yan.

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Fantastic.

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My stick was 170 centimetres high

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and my shadow was 105 centimetres long.

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So the angle of the sun was...

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58 degrees.

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For Jem, well,

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his shadow was 93.6 centimetres.

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So Jem's angle is, well, 61 degrees.

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That means that the angle at the centre of the Earth between Jem in Brighton and me here in Mappleton

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is 61 minus 58, which is three degrees.

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How does that help work out the circumference of the Earth? Let me demonstrate with this pizza.

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HE LAUGHS

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Now if the angle in the centre here is three degrees -

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that's a pretty stingy slice of pizza,

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then I can fit 120 of those

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into the whole pizza, because three times 120 is 360.

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And that means that the distance all the way round the edge is

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just the distance along the edge of one of these slices, times 120.

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The distance from here to Brighton, as the crow flies, is about 330 km,

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so the circumference of the earth must be 330 times 120.

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That comes to 39,600 kilometres. And Eratosthenes - well,

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he calculated the circumference of the earth at 39,690 kilometres.

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How about the real figure?

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Well, modern satellite measurements tell us that

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the circumference of the earth around the poles is 40,008 kilometres.

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So I did really well. And Eratosthenes didn't do too badly either,

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but he didn't get a pizza for it and I do.

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So that's great.

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Now when I was a kid, you couldn't move for predictions

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of exciting robots that would pander to our every whim,

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and obviously nowadays we live alongside robots in our factories,

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in our electrical devices, even in our traffic lights, but somehow,

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I can't help but feel a little disappointed.

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Cute. Yes.

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Sophisticated. Absolutely.

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But the fully autonomous robot companion of my dreams?

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Not yet.

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So why are we still waiting?

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I've come to Edinburgh University's robot lab to find out

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how close we are with the latest tech.

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When I was a kid, the idea was that definitely by now

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we would have robots that could think for themselves,

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they'd be able to mix the perfect martini and make tea

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and would be able to work with us as humans on our terms.

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It just seems that we're not even nearly there,

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or there's been something wrong, there's something holding this up.

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You're right. It hasn't happened, because people probably underestimated

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the amount of things that you need to consider

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when doing apparently simple tasks. Think about an autonomous system,

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for example crossing a road, then it has to make decisions

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on its own, it has to sense the state of the environment.

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So it's a lot more complex.

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A decent robot needs to be capable of performing really complicated tasks,

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like these little fellows, who have mastered the beautiful game.

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Sort of.

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Let me check - these aren't remote-control toy robots,

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these are actually autonomous. Can I say they're autonomous?

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They are autonomous in the sense that they've got its own sensors,

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so it's got cameras, it's got wireless, infra red sensors,

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and they've got some touch sensors.

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That one's just fouled him. He just sort of kicked him in the shin.

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That's a robot red card.

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The basic behaviour's built in, like go for the ball,

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once it reaches the target, aim and kick,

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and the goalkeeper has a basic task of saving it,

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so these typical behaviours are then controlled

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with a higher level artificial intelligence,

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to figure out which of the behaviours to trigger when,

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so that it can achieve the overall goal of trying to defend or score a goal.

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To play football these guys must be pretty clever, but recreating

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anything like human intelligence is unbelievably complicated.

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Even so, his team are making progress.

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"MASTERMIND" THEME

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The robot has a webcam for its eyes, so it can look at the state

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of the game, and figure out the moves you've played and what it has done.

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The most important component

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is the AI or the planning behind it,

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which basically tries to figure out the strategy that you are playing

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and first of all try to defend itself and maybe try and beat you.

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I can see what it's trying to do. I can see exactly how I'm going to lose as well.

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Oh, it won.

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Yeah. Yeah, it won.

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It won. Where's the hammer?

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But it's hardly the kind of personal robot I've got in mind.

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OK.

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I mean, that is incredible, just seeing the strategy there,

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and it can see and knows where to put things,

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but how are we going to put this together and create my ultimate robot?

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I think what we've seen today is that there are bits and pieces

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which are brilliant, but actually what you need for something like a robot butler

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would be to first of all put all these things together,

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into a very fast, reactive robust system, but on top of that, have the robot... give the robot

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the ability to learn and adapt and change, just like you and me do.

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And this might be the answer.

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Although it doesn't look like quite like I expected,

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this is the closest thing yet to a proper independent robot.

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This machine can drive, navigate, and avoid obstacles, all without any human involvement.

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Off we go. Very smooth.

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Sensing, planning and reacting,

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all critical for a real independent thinking robot,

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and they're are all mastered by this vehicle.

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So just how intelligent is this thing?

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It's pretty good, you know. You can even tell it senses

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when you're going up a gradient.

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You can sense it being aware of where it is,

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and the kind of terrain it's driving on,

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as we go down a - ooh, blimey!

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See if it manages this pothole.

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Come on!

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I'm now rather disconcertingly heading towards

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two concrete objects in the middle of the road.

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Very cleverly, the car's spotted them and it's driving round them.

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Look at that. It's amazing.

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All I have to do is sort of sit here. On board there are a whole host of sensors.

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You might be able to see on the roof, that thing spinning around.

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That's a lidar. That sees the world using laser ranging.

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There's also radar on board, there's also various cameras, GPS,

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and all that information about the outside world gets thrown back

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to a big number-crunching computer in the back,

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which makes the decisions, and puts it all forward to the mechanics of the actual car.

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I've got a screen here that gives me all the information coming from the various sensors,

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so I can check the software is all running correctly,

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that the lidar is...lidaring.

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OK, we are going slightly off-piste here.

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Whoa!

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Blimey! It really does have a mind of its own.

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This incredible machine marks a great leap forward

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in the development of autonomous robots

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but the driving force behind it isn't the need for domestic robots.

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It's the need for robots on the battlefield, where very soon, machines like this

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will be doing all sorts of tasks, from reconnaissance to bomb disposal.

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So, something like this is really a test bed for the latest autonomous technology,

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a chance to put it through its paces in a real-world situation.

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In one sense it's great, because you have the potential

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to save lives, but I can't help but wonder where else this could lead.

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Now, there are no plans to fit weapons to this vehicle,

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but that wouldn't be difficult in theory, and then what?

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Instead of my dream robot companion,

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you could imagine its evil nemesis - a Terminator, a Dalek?

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I've come to meet robot ethicist Blay Whitby, to see what he thinks

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about living, working and maybe fighting alongside our mechanical cousins.

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In terms of autonomous robots of the battlefield, we're sort of seeing already

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flying drones, unmanned drones that can get somewhere on their own,

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but don't pull the trigger on their own - there's still a human in the loop.

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That's right.

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At present, there's a human being's finger on the trigger.

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But in the relatively near future we're going to move to

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a situation where these things can autonomously decide to kill.

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We are talking about things with very limited cognitive capacity?

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Incredibly limited cognitive capacity. Well below insect level.

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At present, we don't know how to make robots that are as clever as ants.

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-So these... so not even as clever as an ant?

-Not even as clever as an ant.

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You have got to realise how limited current technology is.

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These things don't have any ethical sensibility,

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they don't have any emotions, they don't have moral values.

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In fact, we haven't been able to programme any common sense into them.

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A lot of autonomous technology seems to come from the military.

0:20:340:20:37

But as it gradually filters down into everyday life,

0:20:370:20:40

are we going to face similar moral and ethical and social questions?

0:20:400:20:45

Everybody is meeting smarter and smarter technology every day. That is going to continue.

0:20:450:20:50

Very close to market technology is that of smart homes,

0:20:500:20:53

which are like an automated apartment which will look after old people.

0:20:530:20:57

Maybe someone would decline in cognitive capabilities. Maybe someone with a brain disorder.

0:20:570:21:01

It will decide what they eat, whether or not they're eating healthily,

0:21:010:21:05

and summon human assistance if they need it.

0:21:050:21:09

The problem is, there's no code of practice for building these things.

0:21:090:21:12

There is no public discussion about what's acceptable and what's not.

0:21:120:21:16

They're simply going to be built. The time for this discussion is now.

0:21:160:21:19

-Very quickly, all-time favourite robot?

-Metal Mickey.

0:21:220:21:25

-R2-D2, without a doubt.

-For me, it's my washing machine.

0:21:250:21:28

Now moving on, I go rocket testing with the Bloodhound team.

0:21:280:21:32

I'm heading to the countryside to meet Daniel Jubb,

0:21:340:21:36

Bloodhound's chief rocket engineer.

0:21:360:21:40

It's taken them several years to design a rocket

0:21:400:21:43

capable of powering Bloodhound to an incredible 1,000 miles an hour.

0:21:430:21:48

And today, we're putting their latest model to the test.

0:21:480:21:51

'Yeah, this is definitely rocket science.'

0:21:510:21:55

It's, eh, it's a little big bigger than the rockets I've built, but broadly similar.

0:21:550:22:00

Indeed. Exactly the same principle.

0:22:000:22:02

How many rockets have you tested so far?

0:22:020:22:05

We've conducted several firings of the six-inch hybrid chamber.

0:22:050:22:08

It's an important development tool

0:22:080:22:11

for the full-size 18-inch chamber for Bloodhound.

0:22:110:22:14

We have learnt from the successful firings and the two failures. One burnt a hole in the motor case.

0:22:140:22:19

The other sent the motor case and nozzle assembly over 300 feet down the desert.

0:22:190:22:24

-Right. So we'll be careful then.

-Absolutely.

0:22:240:22:28

'Daniel's rocket is a hybrid rocket.'

0:22:280:22:32

It means it's got a solid fuel, into which is pumped a liquid oxidiser.

0:22:320:22:36

The fuel he's using is a kind of rubber.

0:22:360:22:38

It's similar to the rubber used in the cushioning of training shoes. Just a bit faster.

0:22:380:22:43

Right, so in comes the oxidiser. The first thing it hits is this catalyst pack.

0:22:430:22:48

Now that makes it split into steam and oxygen.

0:22:480:22:52

The oxygen, under high temperature, hits this rubber and starts burning.

0:22:520:22:57

At a couple of thousand degrees, this gas is expanding rapidly.

0:22:570:23:02

As it expands through this nozzle,

0:23:020:23:04

it gets accelerated to supersonic speeds.

0:23:040:23:07

So what you end up with is a supersonic plasma going in that direction.

0:23:070:23:11

Getting maximum power from the rocket isn't as simple as pumping in as much oxidiser as possible.

0:23:110:23:18

It's critical that the fuel and oxidiser mix in exactly the right proportions.

0:23:180:23:23

These are going to be my rockets.

0:23:230:23:28

I'm going to use plain air as my oxidiser.

0:23:280:23:31

I'm going to use acetylene as my fuel.

0:23:310:23:33

You might think, a stack of fuel, surely that's the best way to go?

0:23:330:23:38

You might think it's best to have loads of oxidiser and not so much fuel.

0:23:380:23:42

So this one...

0:23:420:23:44

Or you might want to try some rocket science, which means in my bottle that's about 77 millilitres.

0:23:440:23:51

My three rockets are now set.

0:23:530:23:55

They've got their fuel/oxidiser ratio. This one stacks of fuel.

0:23:550:23:59

This one stacks of oxidiser.

0:23:590:24:01

This one, hopefully, the scientifically correct formula.

0:24:010:24:05

Time to retire... and fire.

0:24:050:24:08

Three, two, one...

0:24:080:24:11

Look at that!

0:24:180:24:20

Just the right amount of fuel/oxidiser mix.

0:24:220:24:25

It is a massive explosion.

0:24:250:24:28

And that is what you want in a rocket

0:24:280:24:31

if you're going to get to 1,000 miles an hour.

0:24:310:24:33

Ooh!

0:24:350:24:37

Working out how to achieve this perfect mix has been the main challenge for Daniel's team.

0:24:400:24:45

Firing up a rocket of this size is seriously dangerous.

0:24:450:24:50

I guess we get into these?

0:24:500:24:53

So it's a real privilege to be taking part in this test.

0:24:530:24:58

For the Bloodhound rocket,

0:24:580:25:00

our oxygen source is something called high test peroxide, or HTP.

0:25:000:25:06

But although it's fairly stable and non-toxic,

0:25:060:25:09

it still needs to be handled carefully.

0:25:090:25:12

What we're doing is sucking the hydrogen peroxide into this tank.

0:25:120:25:16

Once it's full...

0:25:160:25:18

we then seal it off. The next stage,

0:25:190:25:22

which can only be done once we're clear of the building,

0:25:220:25:25

is it gets pressurised by those nitrogen cylinders there.

0:25:250:25:29

The pressure means there's probably 50 tonnes of force

0:25:290:25:33

trying to burst the top and bottom off that tank.

0:25:330:25:37

'After helping Daniel to load the HTP oxidiser, we slowly open the valve...'

0:25:370:25:42

-800 PSI.

-800. Perfect.

0:25:420:25:46

..before retreating to the safety of the monitoring bunker.

0:25:460:25:50

The rocket's bolted firmly in place.

0:25:570:25:59

We don't want it flying anywhere in this test.

0:25:590:26:03

OK, are we ready?

0:26:030:26:05

To succeed, we want spontaneous ignition. 100% burn in around 10 seconds...

0:26:050:26:10

Close the vent.

0:26:100:26:14

The vent is closed.

0:26:140:26:16

..producing at least 2,000 pounds of thrust.

0:26:160:26:19

Pressurise the tank.

0:26:190:26:21

OK, we're about 15 seconds away.

0:26:210:26:24

Start the countdown.

0:26:240:26:25

Will Daniel's calculations prove right?

0:26:250:26:28

Nine, eight, seven, six, five...

0:26:280:26:32

Valve cracked. Crack more.

0:26:320:26:35

Fire!

0:26:350:26:37

Internal temperature, around 2,500 degrees.

0:26:440:26:48

Internal pressure, 550 PSI. Maximum thrust, 2,500 pounds.

0:26:480:26:54

Test complete.

0:26:570:26:58

Success! Nothing burst! Nothing like... oh! I'm relieved.

0:26:580:27:04

The rocket has performed perfectly, taking the Bloodhound team one step closer

0:27:050:27:10

to their dream of driving at 1,000 miles an hour.

0:27:100:27:15

-That was epic!

-Blimey. I'll tell you what, I wonder if Andy Green,

0:27:150:27:19

who's driving the Bloodhound car, was watching that.

0:27:190:27:22

He might have a little collywobble. You know what I mean?

0:27:220:27:25

I really wouldn't blame him if he was a bit...

0:27:250:27:29

That was just a third-scale model. I was three bunkers away, and it still felt a bit much.

0:27:290:27:33

For the real thing, OK, the real thing, just pumping in the oxidiser

0:27:330:27:36

will be a pump out of a cruise missile.

0:27:360:27:39

And it's hosing in oxidiser because it's powered by a V8 Cosworth Formula One engine.

0:27:390:27:45

The rocket that's going to go on that 1,000 mph car is so big,

0:27:450:27:49

that when it's tested in a few weeks, it will be the biggest rocket test in the UK for 20 years.

0:27:490:27:56

And it is all on our website.

0:27:560:27:59

It's a truly awesome project. OK, that is it for this week.

0:27:590:28:03

Next week, I'm looking at something that bothers a lot of people, and that's forgetting things.

0:28:030:28:08

You know when you walk into a room and can't remember why you're there?

0:28:080:28:11

-It happens to me every day.

-It drives me round the bend. I'm looking at how memory works,

0:28:110:28:16

and what you can do to make sure you never lose your car keys again.

0:28:160:28:19

Nice one. And I'm going to be looking into stem cell research. Still a controversial subject.

0:28:190:28:24

But its potential for use in organ repair and whole-organ transplants

0:28:240:28:29

has moved on in leaps and bounds.

0:28:290:28:31

And our dear Dr Yan? He has finally cracked.

0:28:310:28:35

He'll be inflicting pain on people. You've been warned.

0:28:350:28:38

You really have. We will see you next week. Bye-bye!

0:28:380:28:42

Subtitles by Red Bee Media Ltd

0:28:510:28:54

E-mail [email protected]

0:28:540:28:56

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.