Naked Science Question and Answer and New Horizons

The cat guaranteed to spare you sneezes and wheezes - a US company - Allerca - are marketing a cat which they say will not trigger allergies. The moggies are marketing at $4000 (US) and produce a different form of a genes called Feld1, which is responsible for triggering reactions in sufferers. In trials, blindfolded volunteers were exposed to the allergy-free cat, a regular cat and a furry dummy cat. They were then asked to keep a diary to document any allergy symptoms. The results suggested that the allergy-free cat, called Joshua, was less irritating to the volunteers than the regular cat, named Tiki. Allerca's founder, Simon Brodie, says that he he initially began by trying to engineer a low-allergy cat, but in the process of doing so stumbled upon three animals that naturally make a slightly different "wheeze-free" version of the Feld1 protein. "You could say we got lucky", he says. However, Allerca have yet to publish their work in a peer-reviewed journal so that it can be scrutinised by other scientists. As a result some researchers have expressed doubt over the findings, saying that Allerca should produce evidence that their cat's skin and hair do not bind to human antibodies. Responding to the critics, however, Brodie said "We don't have the data yet, but we do know the animals work. If these scientists are sceptical, and if they happen to be allergic themselves, I would say 'come and hold one of our cats'".

This week Derek is with Professor Hugh Hunt from the University of Cambridge and three student volunteers from the Norwich School. They're going to be throwing books into the air and learning about the science of spin.

To do the experiment, you will need:

- A rectangular (preferably hardback) book

- An elastic band to hold the pages together 

How to do the experiment:

1 - Take the book and put the elastic band around it to keep the pages together. 

2 - Hold the book in your hands so that the book is flat and the spine is facing away from you. 

3 - Throw the book up into the air and make it spin so that the spine moves towards you and then away again. Catch the book and see if it looks any different. 

4 - Now hold the book so that it is flat between thepalms of your hands with the spine facing away from you. Spin the book again, aiming to make the spine come towards you and away again. Look again at the position of the book once you've caught it. (Don't worry if youcan't see any difference in stages 3 and 4!) 

5 - Now hold the book as though you were looking atthe cover ready to read it. The spine should be on the left hand side. Throw it up into the air and make itspin. What changes about the position of the book? How has the cover changed relative to how it was before you threw it?   

What's going on?

In steps 3 and 4, nothing particularly remarkable happens! They spin about the same axis all the way through and land in your hands in the same orientation.  However, when you throw it in step 5, it should have landed in pretty much the same way but rotated round 180 degrees. You will have noticed this because the front cover should be upside down. Anybody watching you throw the book will see that it starts going up normally and spinning but then does a flip when it gets to the top.  So what's happening?

When you throw it up into the air, the book starts spinning as you would like it to spin, but it doesn't last long! It turns out that spin about this particular axis is unstable, and doesn't like to spin in the way you would expect for very long. This makes the book start to tumble out of control. Once it's done this flip, it magically starts spinning nicely again, but the other way round. This means that, when you finally catch the book, it's lying in your hands upside down. 

This is all rather different to the other two ways of spinning the book. These two spin directions are what we call stable. You can think of this by imagining holding a pencil by its tip. If you hold the pencil so that the rubber is pointing downwards, it won't move. In fact, you could hold it like that for hours because gravity is forcing downwards and the direction is stable.

In contrast, if you try to balance a pencil on your finger tip with the rubber pointing upwards, the direction is unstable and the pencil falls down.  You can imagine that this pencil is a little bit like a pendulum. When it's swinging backwards and forwards down the bottom, then it's a stable situation. But if you imagine tipping it right up around 180 degrees, it wouldn't stay there for very long. It would swing down, go right the way round and come back to the top again.

So if it fell to the right, it comes back again from the left. Instabilities quite often involve moving away from where you started and coming back again the other way round. This is why the book turns 180 degrees from its original position. However, if you throw it again, the flip turns the book in the opposite direction and brings you back to the beginning. 

If you toss the book up high enough, it might do two flips. This will make it come back into your hands with the cover in the same orientation as before you threw it. 

These same spinning stabilities and instabilities can be seen in objects such as mobile phones because they're the same shape as books (one long axis, one medium axis and one short axis). Even a cat falling out of a tree uses the same principles to move itself around. 

Chris - We're going to be joined this evening by Hal Weaver who's from the New Horizons mission, and he's joining us now from Johns Hopkins University over in the States. Why are you going to Pluto? What's the point of this?

Hal - It's been dramatic how our image of the solar system has changed over the last ten years. Pluto's been at the forefront of that new understanding. There's been a big controversy about whether or not Pluto is a planet, but it's definitely something called a Kuiper Belt object. This is a new region just outside Neptune's orbit and it was just discovered in 1992. We now know of roughly 1000 objects out there and it's a whole new region of the solar system that hasn't been explored yet; a region that we're calling the realm of the icy dwarfs. Pluto is the prototype of those objects.

Chris - So what do we think is out there, Hal? What are these objects like and why are they worth studying?

Hal - They're worth studying for a number of reasons. One is that because they are so far away from the sun and outside of Neptune's orbit most of the time, they've always been cold since the time that they formed roughly 4.6 billion years ago. As you know, one of the best ways to conserve material is to keep it in a deep freeze. That's exactly what's been done with these objects. They've got a lot of ice and the molecules that they have retained over these last 4.6 billion years basically give us a window back to the time of the formation of the solar system. So by studying these objects now we have a much better insight into what's happening in the early solar system in that region of the solar system. This is in comparison to observing the Earth or other planets, where these objects have had so much evolution over the age of the solar system.

Chris - How long is it going to take New Horizons to reach Pluto? It left in what, February of this year wasn't it?

Hal - It was January the 19th of this year that we took off. We went screaming off the surface of the Earth; it was the fastest spacecraft ever launched going at about 36 000 miles per hour. But even going at those kinds of speeds it's going to take nine and a half years to get to Pluto because Pluto is so far away. It's roughly 30 times further from the Sun than the Earth is. So even though we had the most powerful rockets available and had a very favourable launch, it's going to take a long time. We're heading first of all towards Jupiter and one of the big reasons for going by Jupiter is to get gravity assistance. We're going to get a sling shot effect because Jupiter is so massive, and is by far the largest planet in the solar system with a mass of 320 times that of the Earth. The most important objective of our Jupiter encounter is to hit a little key hole in space; a little spot near Jupiter that will propel us on towards Pluto and cut off three to five years of our travel time and increases our speed by about 20%. But still, it's going to take about nine and a half years to get to Pluto. We know now that we're going to arrive on July 14th 2014.

Chris - How do you actually know that the probe is a) going to survive the journey, and b) be able to operate under those extremes of temperature? It must be about minus 200 degrees Celsius out there near Pluto. How's it going to operate?

Hal - Yeah that's right. There are very harsh conditions out there. But our spacecraft are actually nice and toasty; it's almost like a thermos flask. We have multilayer insulation wrapped around the entire spacecraft and just from the heat generated by the electronics, we generate enough heat to keep all the instruments, the spacecraft body and the telescope and so forth at roughly room temperature even when they're out by Pluto.

Chris - So what sort of science will you be doing at Pluto? In what way will you be interrogating that part of the solar system with the probe?

Hal - There are basically some questions that we want to address that are just too hard to do remotely. We are so far away from Pluto, so first of all we want to know: what does it look like in detail? The Hubble space telescope is the most fantastic space observatory available to us here on Earth, but it can barely resolve Pluto. It's done some magnificent imaging of Pluto but even with Hubble, it looks like a bunch of about ten pixels across. All you can tell is that there are some very bright regions and some very dark regions but it's very hard to tell what's going on. Why are these regions bright and why are they dark? We'll do thousands of times better than that by flying the spacecraft by.

Chris - And when you're out there, how long will it take a message or any of this data you're collecting to get back to Earth each time?

Hal - It's amazing. It turns out that from Pluto it takes four and a half hours for the light to reach the Earth. So the round trip will take about nine hours.

Chris - So it's a long old time. Once you've got to Pluto, will you carry on a go beyond the orbit of Pluto and keep exploring?

Hal - That's exactly right. What we're hoping to do is not to stop at Pluto but continue plunging into this region called the Kuiper Belt. As long as everything is still working then, we have a very good chance, we estimate something like 95% probability, that we'll be able to encounter another small Kuiper Belt object. Even with Pluto, we just discovered a year and a half ago two more satellites that Pluto has besides Charon, the one that was discovered in 1978. We have two more mini satellites; our own mini solar system out at Pluto, so effectively we have four Kuiper Belt objects to look at for the price of one by going past Pluto. The neat thing is that we have one of the largest members of that class and the smallest satellites in that system, and plus we hope to encounter more of the small Kuiper Belt objects to see whether they are like the objects of the Pluto system or very different.

Mucus is very important, especially in your lungs. We did an experiment with this on TV a while ago. Mucus catches all the dust and bits in the air. If you didn't have mucus, all the tiny bits in the air would be carried deep into your lungs, which can do all sorts of damage, especially if it's toxic. As the mucus is sticky, it catches all these bits and you can either bring it up as phlegm or it runs out of your nose, taking all the poisonous nasty stuff with it. The reason that Dee probably has this problem could be down to allergy or some other inflammatory process going on. But usually it's down to something that you're breathing in that's making your airways inflamed. The reaction to an inflammation is to make lots of mucus. How do you get rid of it? Well there's one way to knock it down, which is to take some steroids like you've done. That will help to stop the inflammation quite effectively. The other way is to take some antihistamines. These are good because they stop histamine, which is a class of cells produced by mast cells. Mast cells are coated with an antibody called IgE that recognises allergy-provoking substances. When the allergy-provoking substance binds onto the IgE on the mast cell, it tells the mast cell to pump out this histamine, which is an inflammatory substance that makes you have sticky eyes, itchy eyes and a blocked up nose. If you take antihistamines then you block the action of the histamine before it has a chance to get going.

It's not actually getting any smaller yet but it's stopped getting any bigger, which kind of amounts to the same thing. What we see is a lag between the CFCs or chlorofluorocarbons, which are implicated in causing the ozone hole, going into the atmosphere. Then they react over Antarctica and damage ozone and make the hole bigger. If you see the hole not getting any bigger then that means that the reaction causing it must be slowing down, and at the same time ozone's continuously being remade. So the two processes must now be in balance, meaning that if it keeps on slowing down, within the next few years the hole should start to shrink a little bit. But let's not be too over-confident or complacent about this because the ozone hole is about the size of the American continent.

The reason blood is red is because it's got iron in it. If you look down a microscope at blood, what you'll see are thousands of tiny little red cells that are referred to as bi-concave discs. If you look at them from the side, they look like a number eight and that's because they've got a thick ring round the edge and a flattened centre, a bit like a doughnut. They're crammed with a substance called haemoglobin, and haemoglobin is what carries oxygen around the body. Haemoglobin's a protein - in fact it's four proteins stuck together - and in the centres of each of those four proteins there is an iron (Fe) atom, which gives haemoglobin its red hue. But blood isn't exclusively red. Some drugs can bind to haemoglobin and alter the chemistry of the iron atom, causing the blood to change colour. In fact, a sulphur-containing migraine treatment called sumatriptan can do this in some people, making their blood go green.

Also, many animals have a different form of the haemoglobin protein with a different metal at the centre in place of the iron, which can also alter the colour. The horseshoe crab, for instance, has blue blood because it uses copper (Cu) instead of iron. And the real hippies of the haemoglobin world are a kind of marine annelid worm. It actually has purple blood!

With glasses, there's definitely some kind of environmental effect there. If you spend all your life studying, then you're much more likely to end up with short sightedness. I can see that both Phil and I have glasses on today! In Singapore where there's a very strong emphasis on education from a very early age and lots of people spend lots of time studying, the rates of short sightedness have gone through the roof. There's a lot to be said for people going out onto the sports field and learning to focus their vision in the distance. When you're young and you're body is developing and growing, if you do a lot of close work you don't develop a capacity to see well into the distance. But in terms of degeneration, just because you wear glasses doesn't mean that your eyes are actually degenerating; it just means that they're not working as effectively as they could. With going deaf, on the other hand, there's actually a problem with part of the ear that turns sound waves into electrical signals. That's because over time the tiny nerve cells that do that job get damaged by loud noises, the effects of ageing and the effects of damaging chemicals in the blood stream. Once they're lost, you can't replace them, which is why you get a progressive deafness.