SpaceX Tests Space-Ready Nuclear Power Using Tritium-Driven CubeSat

WEBVTT

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Professor Fred Watson: Hi there.

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Andrew Dunkley: Thanks again for joining us. This is Space

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Nuts. My name is Andrew Dunkley and every

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week we talk astronomy and space science

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and we answer audience questions in our

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alternative show, which, uh, happens,

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um, well, wherever you are. I mean, we

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release it on a Monday, but that doesn't mean

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you listen to it on a Monday. Uh, coming up

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today we've got, uh, a couple of

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nuclear explosive storeys. Uh,

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SpaceX is involved in one of those and

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the other storey is about, uh, blowing things

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up with atomic weapons from space.

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Yes, highly guaranteed. Very, very, uh,

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effective as well. Uh, but I think there's

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probably a reason not to. We'll look at all

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of that. Uh, we're also going to talk about

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where Earth's, uh, dust came from. Quite a

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bit of it, which might come as a bit of a

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surprise. Uh, you just have to look under

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just about every bed and kitchen table in the

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world to find as much dust as there is in the

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world. But we'll see where that, uh, is

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headed. And our galaxy, uh, reaches

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out further than we thought. Apparently, uh,

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there's some interesting science behind that.

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We'll talk about it all on this edition of

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space nuts.

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Professor Fred Watson: 15 seconds. Guidance is internal.

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10, 9. Ignition

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sequence start.

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Professor Fred Watson: Space nuts.

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Professor Fred Watson: 5, 4, 3, 2. 1, 2, 3, 4,

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5, 5, 4, 3, 2, 1.

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Andrew Dunkley: Space nuts.

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Professor Fred Watson: Astronauts report it feels good.

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Andrew Dunkley: And joining us again to talk about all of

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that and more is Professor Fred Watson

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Watson, astronomer at large. Hello,

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Fred Watson.

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Professor Fred Watson: Hello, Andrew. Good to see you. Good to see

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you. Yes.

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We sort of missed a few days, haven't we?

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Yes.

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Andrew Dunkley: Uh, you've been off conferencing.

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Professor Fred Watson: Yes. So the annual science meeting,

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as it's called, of the National Astronomy

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Society, the Astronomical Society of

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Australia, it's where all the professional

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astronomers get together and, uh, talk about

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what they've been doing, their research. Uh,

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it was a big meeting. There were, I would

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have guessed, maybe a couple of hundred

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people there altogether. Uh, that's quite big

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for astronomers in a country that's only got

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700 astronomers in it.

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Professor Fred Watson: Yeah.

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Professor Fred Watson: Uh, but, um, what was interesting and

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what was very, I think,

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heartening for me was the number of

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youngsters that were there. I call them

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youngsters, you know, people under 50

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people, um, the new generation of

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astronomers, uh, most of them whom I didn't

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know and they've no idea who I am, and that's

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fine. Uh, that all was okay. It

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just contrasts with a few years ago. So when

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I was the astronomer in charge of the

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observatory at, uh, Coonabarabran, uh,

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we were kind of the Shopkeepers. So all these

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astronomers used to come through, stay in the

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lodge and do their research using the

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telescope. So I knew a large fraction of

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the astronomical population of Australia. But

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that's changed, uh, because my job,

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that job is no longer mine. Uh,

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and so I don't see people the same way. But

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it was very nice to meet a lot of new faces

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and catch up with some very old faces as

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well, some even older than mine. Um, and we

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also discussed matters such as the future

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of Australian astronomy because that's

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uh, in a interesting

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state at the moment. With the government

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having declined, uh, to

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engage in membership with the European

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Southern Observatory. We are now working on

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plan B. Uh, and um. Well, it looks

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promising.

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Andrew Dunkley: Yes, fingers crossed. A lot going on.

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Okay, um, we should probably get

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stuck into these storeys because there's a

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lot to discuss. The first storey is a double

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banger about nuclear, um, energy and

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atomic weapons.

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Uh, we'll start off with the storey about

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SpaceX. And

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um, they're looking at nuclear power

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in space, nuclear powered satellites. What's

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the storey here?

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Professor Fred Watson: It's a test launch, really. A launch of

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a cubesat basically that um,

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has not a nuclear reactor inside but

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um, basically a capsule of something called

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tritium which is sometimes called heavy

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hydrogen. It's hydrogen with two

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electrons in it as well as the proton at uh,

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its centre. And it's radioactive. Uh,

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tritium is um, I suppose you'd call it

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mildly radioactive. Um, we used to

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use tritium standard lamps at the

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observatory when I was working there, which

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was a little capsule of tritium with some

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phosphor on it. Um, and

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um, basically the electrons released by the

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tritium lit up the phosphor and

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gave a very constant glow so we could use it

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to calibrate other, other instruments.

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So I've been close up and personal with um,

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a little nuclear power source a bit like

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that, but it was just making faint light.

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This one is one that's been uh,

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developed by a private company. Um,

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and it's uh, basically a

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company called City Labs, uh, in the United

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States. Uh, they've built

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um, a little, as I said, it's

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effectively a cubesat which has this um,

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little nuclear, not nuclear

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reactor, but nuclear power source inside a

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tritium, uh, source that I've just been

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talking about, which doesn't actually convert

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the electrons into light, it

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converts them directly into electricity.

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So they've got these panels on the side of it

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that take the electrons that come from the

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tritium and turn them straight into

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um, electricity. Ah, it's

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Called Bohr B O H R, uh, which is

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a bit of a play on words because Niels Bohr

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was one of the great founders of quantum

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theory. Same spelling, um

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Danish one, A uh, Danish uh

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scientist, uh and it stands for

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Beta Voltaic. And a

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Beta Voltaic is taking the beta particles,

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which are otherwise known as electrons, uh

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turning them into electricity. So it's Beta

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Voltaic orbital high reliability

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spacecraft. That's where you get the Bohr

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from and it's been launched. Uh,

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so SpaceX's part in this storey is just to

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provide the taxi, uh up into um, up

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into orbit. It's a transporter, uh

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mission, um, basically

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one of uh, SpaceX's taxi rides to get stuff

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up and down from uh, or up to orbit,

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coming down to different storey and most of

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them just burn up.

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Professor Fred Watson: Yes.

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Professor Fred Watson: Uh, but it is uh, probably the

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first CubeSat to include a nuclear

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power system. Uh and

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maybe, just maybe we'll sort of illuminate

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the way for a new generation of uh,

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spacecraft which are equipped with uh,

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these nuclear power sources.

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Andrew Dunkley: I suppose they have to look at alternatives

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because we've been reliant, fairly

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reliant anyway on solar energy in

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space, um particularly with our uh, orbiting

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satellites, but also with um, the

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International Space Station and others. Um,

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but the time will come where we are

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in places where there won't be that

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much sunlight and

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in some places there won't be any at all. And

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solar panels are going to be useless.

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Professor Fred Watson: Uh, that's correct. And we've seen already

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um, the use of these UH RTGs,

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radioisotope thermoelectric

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generators, uh which are carried by both

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the Curiosity and the uh

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Perseverance rovers, uh as well as

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spacecraft in deep space like uh,

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Voyager 1, Voyager 2, Pioneers. I think

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they've got them as well. And these are

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spacecraft that are so far from the sun that

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you get very little light from the sun,

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uh in terms of um, you know, using it to

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generate electricity. So they've, they've had

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their nuclear power sources for a long time.

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They are quite different though from what

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we're talking about here. There are, I think

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it's 13 kilogrammes if I remember rightly, is

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the amount in a canister of plutonium

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dioxide, uh which is

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decaying all the time and getting very hot as

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it does that and that heat is then used

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to generate electricity, uh and

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it actually dies away as time goes on. So

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these nuclear uh, RTGs, the

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radioisotope thermoelectric generators

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gradually lose their power, um, and that's

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why we hear from time to time and we usually

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report this on space nuts. We hear of

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uh, uh instruments on board Voyager 1

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being turned off to save the power.

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Andrew Dunkley: Yeah. And that happened again not so long

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ago.

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Professor Fred Watson: I think that's correct. Yes it did.

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There was one turned off uh quite recently

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but perhaps more to the point and

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uh, what you've just said about there being

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some places that have no sunlight whatsoever,

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uh that applies to uh, those deep

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craters near the moon's south pole

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and that's where we're thinking of exploring.

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So it may be that um, these

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beta voltaic arrays

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uh uh, or devices might well

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be the future of power generation

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near the moon's south pole because you're in

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places where there's no light whatsoever from

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the sun.

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Andrew Dunkley: That's absolutely true. Darn cold too. It is.

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Professor Fred Watson: It is always cold there. Yes, yes

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indeed.

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Andrew Dunkley: Uh, uh that's a really interesting storey and

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we're obviously in the early phases of

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finding these alternatives. Is um, tritium

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safe?

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Professor Fred Watson: Uh, it's probably something regarded

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uh, treated carefully.

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It is generally safe. I mean we never took

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any real precautions with the device that we

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had on the telescope. Maybe we should

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have done. Although uh, most of

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us are still around and in fairly good

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health. But um, yes they are

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releasing electrons, uh beta radiation,

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uh, it's um, uh if you had a

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high level though of tritium, if you had a

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significant amount of it then you would have

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to be careful about how you handled it and

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where it was put and if it needed shielding

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and things of that sort.

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Andrew Dunkley: Yeah. So uh, don't sprinkle it on your

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cornflakes or anything like that.

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Professor Fred Watson: Yes, that's right. It's best to avoid it if

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you can.

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Andrew Dunkley: Yeah. Sugar's damaging enough already.

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Professor Fred Watson: It is. Tell my dentist about it.

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Andrew Dunkley: If you'd like to um, read up on that storey

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about the uh, the launch of the cubesat with

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the tritium nuclear ah power device

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they're testing. Uh you can read about

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it@dailygalaxy.com.

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um, let's keep on this theme

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Fred Watson, because that's the good news.

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Uh the bad news is um,

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the the problem of exploding nuclear

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devices in space or firing nuclear

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devices from space to targets on Earth.

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That's, that's a real issue. I know.

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Um, was it back in the 80s the

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Star wars um

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um push was uh, all the rage in the news

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at the time and uh, that got shut down pretty

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quickly.

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Professor Fred Watson: Star wars was um, a

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Reagan era initiative. Yes, I think it was, I

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think it was um, uh basically

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electromagnetic Radiation to zap your

275
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satellites. It wasn't nuclear though, uh,

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because nuclear weapons are in space, are

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prohibited by the outer Space Treaty

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1967.

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Andrew Dunkley: So what's happening?

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Professor Fred Watson: They're not allowed. But,

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um, there may be some there

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launched by powers that

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stretch um, the envelope, if I can put it

284
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that way. Governments that stretch the

285
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envelope. And uh, we don't know. We don't

286
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know if there are any. You know, they're

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banned by the uh, Outer Space Treaty. So

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there shouldn't be any nuclear weapons in

289
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space. But that's all very well.

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Professor Fred Watson: Um.

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Professor Fred Watson: There's a lot of things that shouldn't happen

292
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but do happen. And um. So it may be

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that perhaps there are nuclear weapons in

294
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space. So the question is,

295
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um, how do you detect them if there are,

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ah, these weapons? Um,

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and um, that's

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where this piece of research, uh, from

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the Massachusetts Institute of Technology

300
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has come from. It's um, a um, person

301
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whose name is Areg Dana

302
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Gulian. Sounds uh, like an Armenian name.

303
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Does that usually I a n on the end. Armenian.

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An associate professor of nuclear science and

305
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engineering at the Massachusetts Institute of

306
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Technology. And he has

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um, essentially

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thought of a neat way,

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uh, of building a device that

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you could fly in the vicinity

311
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of a satellite to detect whether

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it is carrying nuclear weapons.

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Um, and it's all about the subatomic

314
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particles, uh, that um, you know,

315
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that, that nuclear um,

316
00:13:13.310 --> 00:13:16.250
weapons are all about. It's all about uh,

317
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neutrons and uh, you know, the nuclear

318
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nuclei of atoms. That's where it all comes

319
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from. Um, so

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what he has suggested, and I might

321
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quote, um,

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I might quote from uh, Dr. Dana

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Gulian's work. Uh

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the risk is that

325
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if you did explode a nuclear weapon in

326
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low Earth orbit, then you basically wreck low

327
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Earth orbit for everybody. It's not the

328
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blast, it's just the subatomic particles that

329
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do it. Uh, and so what he goes on to say

330
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is this danger is compounded by the lack

331
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of a verification mechanism for the Outer

332
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Space Treaty. Um,

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there's no detection methodologies that have

334
00:14:04.340 --> 00:14:06.620
been proposed in the scientific literature.

335
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So what he's saying is here's a concept and

336
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feasibility study, um, for

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verifying a satellite's compliance

338
00:14:14.540 --> 00:14:17.100
to the Outer Space Treaty by observing

339
00:14:17.420 --> 00:14:20.220
the neutrons induced by spallation

340
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from the approximately

341
00:14:23.660 --> 00:14:26.080
giga electron volt protons in the

342
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Innovant Allen radiation belts, which is

343
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a slightly complicated and technical way of

344
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saying, uh, you've already got subatomic

345
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particles in the radiation belts around

346
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our planet. Um, if you can,

347
00:14:41.650 --> 00:14:44.200
um, basically watch the way,

348
00:14:44.790 --> 00:14:47.720
um, a satellite responds

349
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to those protons that are in the radiation

350
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belts. Um, if for example that uh,

351
00:14:53.400 --> 00:14:55.320
bombardment of protons from the radiation

352
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belts causes neutron neutrons to be

353
00:14:58.110 --> 00:15:00.660
uh, emitted then you can

354
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have a fair degree of

355
00:15:04.250 --> 00:15:06.220
um, confidence that there might be a nuclear

356
00:15:06.220 --> 00:15:08.900
weapon on board or a lot of nuclear fissile

357
00:15:08.900 --> 00:15:11.540
material, heavy elements like uranium.

358
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That's the kind of thing that this is all

359
00:15:14.100 --> 00:15:16.980
about. And so um,

360
00:15:18.210 --> 00:15:21.180
uh, what this is all

361
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about is building uh, a

362
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satellite that can detect

363
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uh, neutrons uh, coming

364
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from radioactive material. And

365
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he's basically suggesting a

366
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detector, uh, uh, uh, what

367
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he calls an inspector satellite that flies

368
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by, uh, the satellite that you're

369
00:15:44.460 --> 00:15:46.140
interested in finding out whether it's got

370
00:15:46.140 --> 00:15:48.980
nuclear weapons. And it's got these detectors

371
00:15:49.210 --> 00:15:51.420
uh, which are almost like X ray detectors.

372
00:15:51.420 --> 00:15:54.380
The kind of things that you see now when you

373
00:15:54.380 --> 00:15:56.180
go for an X ray, a chest X ray. They're

374
00:15:56.180 --> 00:15:58.360
electronic, they're not photograph they used

375
00:15:58.360 --> 00:16:01.240
to be back in the day. Um, and they've got

376
00:16:01.240 --> 00:16:03.560
what are called neutron sensors, uh they're

377
00:16:03.560 --> 00:16:06.560
called scintillators. And uh, you

378
00:16:06.560 --> 00:16:09.360
put those in a special arrangement with

379
00:16:09.440 --> 00:16:11.760
other basically other detectors.

380
00:16:12.320 --> 00:16:15.280
Uh, and um, if you do that then

381
00:16:15.840 --> 00:16:18.680
you can apparently sort out the

382
00:16:18.680 --> 00:16:20.960
neutrons from the other natural

383
00:16:21.200 --> 00:16:23.440
subatomic particles that are floating around

384
00:16:23.760 --> 00:16:26.320
near the radiation belts. And the neutrons

385
00:16:26.320 --> 00:16:28.840
come from radioactive material and you can

386
00:16:28.840 --> 00:16:30.500
also see the direct direction that they're

387
00:16:30.500 --> 00:16:33.140
coming from. So you can sort of point this

388
00:16:33.140 --> 00:16:35.820
thing towards your target satellite, uh, the

389
00:16:35.820 --> 00:16:37.380
one that you suspect might have nuclear

390
00:16:37.380 --> 00:16:39.940
weapons and it will give you the direction of

391
00:16:39.940 --> 00:16:42.540
where it's coming from. Um, and

392
00:16:42.780 --> 00:16:45.020
so uh, just a quote,

393
00:16:45.560 --> 00:16:48.140
um again from Dr. Dana

394
00:16:48.140 --> 00:16:51.100
Gulian. Um, the calculations show

395
00:16:51.260 --> 00:16:54.060
that a nine unit cubesat size

396
00:16:54.060 --> 00:16:56.340
detection platform, that's something the size

397
00:16:56.340 --> 00:16:58.500
of, what's that, about three loaves of bread?

398
00:16:58.500 --> 00:17:00.420
Something of that sort size. It's quite

399
00:17:00.420 --> 00:17:03.370
small. Um, it can identify a

400
00:17:03.370 --> 00:17:06.210
thermonuclear weapon from a distance of

401
00:17:06.210 --> 00:17:09.090
four kilometres in approximately one

402
00:17:09.090 --> 00:17:12.050
week of observation. Now that's quite a long

403
00:17:12.050 --> 00:17:15.010
time but uh, apparently

404
00:17:15.010 --> 00:17:17.490
if you could get it to within one kilometre

405
00:17:17.970 --> 00:17:20.650
it would take you about an hour to detect a

406
00:17:20.650 --> 00:17:22.690
weapon. And that's

407
00:17:23.490 --> 00:17:26.290
promising. That's one flyby, that's you know,

408
00:17:26.450 --> 00:17:29.330
an hour of proximity, uh, you could do that

409
00:17:29.330 --> 00:17:32.170
as you go past the

410
00:17:32.170 --> 00:17:35.070
suspect satell. If you got an hour in

411
00:17:35.230 --> 00:17:37.730
close uh, contact with it or close uh,

412
00:17:38.030 --> 00:17:40.390
proximity to it within a

413
00:17:40.390 --> 00:17:43.150
kilometre, uh, then you might well

414
00:17:43.630 --> 00:17:45.750
detect a nuclear weapon on board. And of

415
00:17:45.750 --> 00:17:47.350
course you could improve that if you had more

416
00:17:47.350 --> 00:17:49.950
than one of these inspector satellites. If

417
00:17:49.950 --> 00:17:51.790
you multiplied them up, then you could get,

418
00:17:51.870 --> 00:17:53.990
uh, quite significant improvements in that

419
00:17:53.990 --> 00:17:56.030
performance. So it's really quite

420
00:17:56.030 --> 00:17:58.430
interesting. Um, uh, one

421
00:17:58.830 --> 00:18:01.620
quote that I really liked, um,

422
00:18:02.060 --> 00:18:04.890
and I'm going to read, uh,

423
00:18:04.890 --> 00:18:07.220
from, uh. Universe Today has a very nice

424
00:18:07.220 --> 00:18:09.380
article on this. The last sentence is, right

425
00:18:09.380 --> 00:18:12.300
now, nations like the USA and Russia rely on

426
00:18:12.300 --> 00:18:14.540
intelligence to know what the other is doing.

427
00:18:14.860 --> 00:18:17.300
And as we know from history, intelligence can

428
00:18:17.300 --> 00:18:20.260
get things wrong. You can fake intelligence,

429
00:18:20.260 --> 00:18:23.020
said Dr. Dana Gulian, but you can't fake

430
00:18:23.020 --> 00:18:25.820
physics. I like that. Yeah, it's true. So

431
00:18:26.060 --> 00:18:27.910
you could do it by physics. Yeah.

432
00:18:28.150 --> 00:18:31.110
Andrew Dunkley: They do, uh, mention in this particular

433
00:18:31.190 --> 00:18:33.590
article that there's one suspect satellite

434
00:18:33.590 --> 00:18:35.750
that seems to have been launched by Russia.

435
00:18:35.990 --> 00:18:38.990
And the bottom line is that it's

436
00:18:38.990 --> 00:18:41.670
been put in an orbit that is very strange

437
00:18:42.550 --> 00:18:45.230
and very hostile in terms

438
00:18:45.230 --> 00:18:47.910
of its radiation, uh, in that area.

439
00:18:47.910 --> 00:18:50.830
And the question is asked. Well, it says no

440
00:18:50.830 --> 00:18:52.750
one puts satellites there because it's highly

441
00:18:52.750 --> 00:18:55.550
radioactive. Why would you put a satellite in

442
00:18:55.550 --> 00:18:58.070
that orbit? So that's one they've already.

443
00:18:58.670 --> 00:19:01.110
They haven't identified as maybe carrying a

444
00:19:01.110 --> 00:19:02.910
nuclear weapon, but they've certainly

445
00:19:03.230 --> 00:19:04.990
identified it as suspicious.

446
00:19:05.310 --> 00:19:08.090
Professor Fred Watson: Yes, that's correct. And so, um.

447
00:19:08.090 --> 00:19:10.150
Yes, highlighting that, I think, you know,

448
00:19:10.150 --> 00:19:12.950
puts this article in context. It

449
00:19:12.950 --> 00:19:14.810
tells you that this is a real issue and, um,

450
00:19:14.910 --> 00:19:17.070
we kind of need to work on how you might

451
00:19:17.070 --> 00:19:19.150
detect, uh, nuclear weapons in space.

452
00:19:19.870 --> 00:19:22.150
Andrew Dunkley: Of course, the other side of it is if you do

453
00:19:22.150 --> 00:19:24.150
identify a satellite that's carrying a

454
00:19:24.150 --> 00:19:26.770
nuclear weapon, what do you do next?

455
00:19:27.410 --> 00:19:29.130
It's like trying to teach people not to

456
00:19:29.130 --> 00:19:31.010
overtake emerging lanes, isn't it?

457
00:19:31.660 --> 00:19:34.610
Professor Fred Watson: Uh, yes. Uh, but,

458
00:19:34.780 --> 00:19:37.090
uh, it's worse than that really, because. A

459
00:19:37.090 --> 00:19:39.610
little bit, yeah, you know, we have

460
00:19:39.610 --> 00:19:41.930
nations that completely disregard

461
00:19:41.930 --> 00:19:44.330
international law. They invade other

462
00:19:44.330 --> 00:19:47.250
countries without so much as a,

463
00:19:47.810 --> 00:19:49.970
you know, a sniff of the,

464
00:19:50.580 --> 00:19:53.370
um, um. Of the, um.

465
00:19:53.570 --> 00:19:55.310
All the international treaties, they just,

466
00:19:55.380 --> 00:19:57.700
Just run amok among them and away they go.

467
00:19:58.220 --> 00:20:01.060
Uh, and yes, so that's the possibility that,

468
00:20:01.060 --> 00:20:02.340
uh, we might already have them.

469
00:20:02.820 --> 00:20:04.660
There is a kind of

470
00:20:05.700 --> 00:20:07.780
corollary of this which I was thinking of

471
00:20:07.780 --> 00:20:10.700
when I read this, Storey. Um, and

472
00:20:10.700 --> 00:20:12.820
that is that back in the 70s,

473
00:20:13.580 --> 00:20:15.540
uh, gamma ray

474
00:20:16.180 --> 00:20:18.260
satellites were launched,

475
00:20:18.660 --> 00:20:21.100
satellites that detect gamma radiation. And

476
00:20:21.100 --> 00:20:23.900
that was to detect any in

477
00:20:23.900 --> 00:20:26.900
atmosphere nuclear tests, uh, conducted on,

478
00:20:27.680 --> 00:20:29.640
uh. Because there was a test ban treaty that

479
00:20:29.640 --> 00:20:32.600
was signed, uh, all the signatories

480
00:20:32.600 --> 00:20:34.920
said, no, we won't test nuclear, uh, weapons

481
00:20:34.920 --> 00:20:37.560
in the atmosphere. Uh, but they had to

482
00:20:37.560 --> 00:20:40.000
verify it. And so the verification process

483
00:20:40.080 --> 00:20:42.480
involved, uh, a number of satellites being

484
00:20:42.480 --> 00:20:44.280
launched that could detect gamma rays which

485
00:20:44.280 --> 00:20:46.880
would be emitted by a nuclear bomb being

486
00:20:46.880 --> 00:20:49.200
detonated in the atmosphere. Uh,

487
00:20:49.600 --> 00:20:52.320
now none were. But those

488
00:20:52.320 --> 00:20:54.520
satellites are what detected gamma ray

489
00:20:54.520 --> 00:20:57.000
bursts. These um, you know, fascinating

490
00:20:57.000 --> 00:21:00.000
pulses of radiation that come from, uh, from

491
00:21:00.000 --> 00:21:02.800
explosions deep in space. Yeah, of course,

492
00:21:03.200 --> 00:21:05.960
man made explosions, but natural ones. Yes.

493
00:21:05.960 --> 00:21:08.480
Andrew Dunkley: Because if they do start detecting nuclear,

494
00:21:08.890 --> 00:21:11.600
uh, weapons in space, then the

495
00:21:11.600 --> 00:21:14.040
parties involved, uh, they won't say, oh,

496
00:21:14.040 --> 00:21:15.520
sorry, sorry, we'll take them all down.

497
00:21:16.000 --> 00:21:17.520
They'll find ways of hiding them.

498
00:21:18.320 --> 00:21:20.160
Professor Fred Watson: Probably. Yes, that's probably right.

499
00:21:21.200 --> 00:21:22.740
Andrew Dunkley: Gosh, it's tough, isn't it?

500
00:21:23.490 --> 00:21:24.810
Professor Fred Watson: Uh, tough world we live in.

501
00:21:24.890 --> 00:21:27.770
Andrew Dunkley: Indeed. Uh, and beyond it in some

502
00:21:27.770 --> 00:21:29.690
respects. Uh, you can read that

503
00:21:29.690 --> 00:21:32.610
storey@universetoday.com. this

504
00:21:32.610 --> 00:21:34.650
is space Nuts with Andrew Dunkley and

505
00:21:34.650 --> 00:21:35.930
Professor Fred Watson Watson.

506
00:21:40.410 --> 00:21:41.530
Space Nuts.

507
00:21:42.480 --> 00:21:45.290
Uh, next storey, Fred Watson, uh, is

508
00:21:45.290 --> 00:21:48.290
looking at, uh, all the dust on Earth

509
00:21:48.290 --> 00:21:50.850
and where it might have come from. Now I was

510
00:21:50.850 --> 00:21:52.610
thinking cats because

511
00:21:53.650 --> 00:21:56.570
they do shed. Uh, but it's uh, a bit

512
00:21:56.570 --> 00:21:59.330
more involved than that. And what

513
00:21:59.330 --> 00:22:01.650
is really interesting about this storey is

514
00:22:01.730 --> 00:22:04.130
they think a heck of a lot of it came from

515
00:22:04.130 --> 00:22:05.010
one source.

516
00:22:07.010 --> 00:22:09.410
Professor Fred Watson: That's right. And it's a mysterious one as

517
00:22:09.410 --> 00:22:11.730
well. Um, so this is

518
00:22:12.130 --> 00:22:14.820
quite a nice storey, uh, from publishing, uh,

519
00:22:15.290 --> 00:22:18.260
Science Adventures. Um, it's

520
00:22:18.420 --> 00:22:20.420
about, uh, the

521
00:22:20.900 --> 00:22:23.620
micrometeorites that bombard the Earth.

522
00:22:24.340 --> 00:22:27.180
And it's a bit surprising, this

523
00:22:27.180 --> 00:22:29.780
stuff. Uh, you know, we think of meteorites

524
00:22:29.780 --> 00:22:32.020
as big chunks of rock that come through the

525
00:22:32.020 --> 00:22:34.780
atmosphere, they have a blaze of glory and

526
00:22:34.780 --> 00:22:36.820
then land on the Earth somewhere. And

527
00:22:38.260 --> 00:22:41.100
what we've got there is um, a

528
00:22:41.100 --> 00:22:43.980
free sample of extraterrestrial

529
00:22:43.980 --> 00:22:46.340
material. But there are also these

530
00:22:46.340 --> 00:22:48.900
micrometeorites which rain on the Earth's

531
00:22:48.900 --> 00:22:50.960
atmosphere and they're dust particles, as

532
00:22:50.960 --> 00:22:52.690
you've kind of hinted. Uh,

533
00:22:53.820 --> 00:22:56.520
um, and they're sort of always

534
00:22:56.520 --> 00:22:59.280
falling on Earth. Uh, and that,

535
00:22:59.860 --> 00:23:02.720
uh, is again, it's a free gift from space.

536
00:23:03.500 --> 00:23:05.760
Um, I think. So I was sort of

537
00:23:06.320 --> 00:23:09.160
vaguely involved with this stuff probably 50

538
00:23:09.160 --> 00:23:12.120
years ago, back in the 70s. I think they

539
00:23:12.120 --> 00:23:14.670
were then called Brownlee particles. Um.

540
00:23:14.880 --> 00:23:16.400
Oh, that sounds familiar. We're talking

541
00:23:16.400 --> 00:23:19.200
about. Yeah. Uh, but they're now,

542
00:23:19.440 --> 00:23:21.760
I think, called cosmic spherules. Uh, I

543
00:23:21.760 --> 00:23:23.760
should cheque whether Brownlee particles and

544
00:23:24.000 --> 00:23:26.920
cosmic spherules are the same thing, but

545
00:23:26.920 --> 00:23:29.920
basically what they are

546
00:23:29.920 --> 00:23:32.880
is bits of meteor that have

547
00:23:33.040 --> 00:23:35.880
melted as they come down through the

548
00:23:35.880 --> 00:23:36.960
Earth's atmosphere, but

549
00:23:38.640 --> 00:23:40.760
they actually survive into the inner

550
00:23:40.760 --> 00:23:43.080
atmosphere and they cool down and they form a

551
00:23:43.080 --> 00:23:46.060
little sphere because the um, basically the

552
00:23:46.060 --> 00:23:48.380
surface tension of molten material brings

553
00:23:48.380 --> 00:23:51.340
them into a sphere. Uh, and that

554
00:23:51.740 --> 00:23:54.540
uh, is the storey so far

555
00:23:54.540 --> 00:23:57.100
because that um, heating

556
00:23:57.340 --> 00:24:00.060
that you, that they experience as

557
00:24:00.060 --> 00:24:03.020
the sort of parent Body, the meteor. Meteor

558
00:24:03.020 --> 00:24:04.820
or meteorite, as it comes through the

559
00:24:04.820 --> 00:24:07.410
atmosphere, it, um,

560
00:24:07.580 --> 00:24:09.580
kind of destroys their chemical

561
00:24:10.140 --> 00:24:12.340
structure, you know, the minerals in it. It

562
00:24:12.980 --> 00:24:15.300
get metamorphosed, they get changed because

563
00:24:15.300 --> 00:24:16.700
they've been subject to very high

564
00:24:16.700 --> 00:24:19.580
temperatures. Um, but there is

565
00:24:19.580 --> 00:24:22.180
a technique, uh, that allows you

566
00:24:22.340 --> 00:24:25.340
to look at, uh, some

567
00:24:25.340 --> 00:24:27.660
of the characteristics of these

568
00:24:27.660 --> 00:24:30.580
objects that is not destroyed by

569
00:24:30.740 --> 00:24:33.380
heat. And it's the oxygen

570
00:24:33.780 --> 00:24:36.740
isotope signature, uh, which we've

571
00:24:36.740 --> 00:24:38.020
talked about before. We've talked about

572
00:24:38.020 --> 00:24:40.820
isotopes and how they, uh, you know, how we

573
00:24:40.820 --> 00:24:42.780
distinguish between heavy water and normal

574
00:24:42.780 --> 00:24:44.480
water and all of that sort, sort of thing.

575
00:24:45.200 --> 00:24:47.970
That's. So it's basically the. The number of,

576
00:24:47.970 --> 00:24:50.680
uh, neutrons in an atom. Um,

577
00:24:51.280 --> 00:24:53.440
so you've got these oxygen

578
00:24:53.440 --> 00:24:55.600
signatures, uh, that,

579
00:24:56.930 --> 00:24:58.960
um, essentially, uh, let you,

580
00:24:59.950 --> 00:25:02.520
ah, group these cosmic

581
00:25:02.520 --> 00:25:05.160
spherules, the Brownlee particles, if that's

582
00:25:05.160 --> 00:25:07.840
what they are. Um, and it turns out

583
00:25:08.000 --> 00:25:10.760
that so, so people do, you know, they do

584
00:25:10.760 --> 00:25:13.640
population census statistics on these objects

585
00:25:13.640 --> 00:25:16.360
to find out, uh, what

586
00:25:16.360 --> 00:25:18.280
relationships they bear with one another.

587
00:25:19.560 --> 00:25:22.400
About 10% of them of these

588
00:25:22.400 --> 00:25:24.880
ferals that have been identified and

589
00:25:24.880 --> 00:25:27.800
analysed collect in a group

590
00:25:27.960 --> 00:25:30.760
that has got the wonderful name of Group

591
00:25:30.760 --> 00:25:33.560
four, uh, which presumably means

592
00:25:33.560 --> 00:25:36.230
there's another three as well. Yeah. Um,

593
00:25:36.250 --> 00:25:39.130
and it's, uh, the. Again, what

594
00:25:39.690 --> 00:25:42.570
makes them stand out in this group is the

595
00:25:42.970 --> 00:25:45.650
oxygen isotope signature that I just

596
00:25:45.650 --> 00:25:48.290
mentioned before. It's depleted in, uh, an

597
00:25:48.290 --> 00:25:50.250
isotope called oxygen 16.

598
00:25:51.210 --> 00:25:54.010
But here's where the storey gets very

599
00:25:54.010 --> 00:25:56.450
interesting because, um,

600
00:25:57.610 --> 00:26:00.330
no known meteorites have

601
00:26:00.330 --> 00:26:03.210
that same oxygen isotope signature.

602
00:26:03.690 --> 00:26:06.580
And you'd expect, uh, if these

603
00:26:06.580 --> 00:26:09.460
things were common, that there would be

604
00:26:09.700 --> 00:26:12.420
meteorites, uh, that match them in their

605
00:26:12.420 --> 00:26:15.220
composition. Uh, and often with

606
00:26:15.220 --> 00:26:17.020
meteorites we can get an idea where they've

607
00:26:17.020 --> 00:26:19.260
come from. Uh, most of them come from the

608
00:26:19.260 --> 00:26:21.300
asteroid belt from collisions between

609
00:26:21.300 --> 00:26:23.980
asteroids. Uh, so, uh,

610
00:26:24.560 --> 00:26:27.500
um, that is a bit mysterious

611
00:26:27.500 --> 00:26:30.420
that we've got these subatomic, sorry, these

612
00:26:31.710 --> 00:26:34.150
small spherules of material that have come

613
00:26:34.150 --> 00:26:36.670
down through the atmosphere, uh, and got that

614
00:26:36.910 --> 00:26:39.790
globular shape. Um, it's

615
00:26:40.110 --> 00:26:42.670
mysterious that we don't know. We don't see

616
00:26:42.670 --> 00:26:45.350
any meteorites that match their

617
00:26:45.350 --> 00:26:46.030
composition.

618
00:26:46.589 --> 00:26:47.069
Andrew Dunkley: Weird.

619
00:26:47.550 --> 00:26:50.510
Professor Fred Watson: It is weird, yes. Uh, and so what

620
00:26:50.510 --> 00:26:53.160
they're suggesting is that, um,

621
00:26:53.160 --> 00:26:55.950
it's basically something that

622
00:26:55.950 --> 00:26:58.390
comes from an asteroid, uh,

623
00:26:58.390 --> 00:27:01.230
whose characteristics are unusual, uh,

624
00:27:01.230 --> 00:27:03.970
that we have not, uh, yet, um,

625
00:27:03.970 --> 00:27:04.970
identified it.

626
00:27:06.250 --> 00:27:09.210
Andrew Dunkley: Wow. Okay, so we're

627
00:27:09.210 --> 00:27:09.690
still looking.

628
00:27:10.330 --> 00:27:12.890
Professor Fred Watson: We're still looking. There's a sort of sub

629
00:27:12.890 --> 00:27:14.540
mystery as well because, um,

630
00:27:17.450 --> 00:27:19.770
a detailed analysis of this, you can break

631
00:27:19.770 --> 00:27:22.370
that Group 4 stuff down into other smaller

632
00:27:22.370 --> 00:27:24.890
groups. And, uh, some of them

633
00:27:25.290 --> 00:27:28.210
Basically show signs of having had two

634
00:27:28.210 --> 00:27:31.080
different, uh, minerals in

635
00:27:31.080 --> 00:27:33.320
them before they entered the Earth's

636
00:27:33.320 --> 00:27:35.910
atmosphere. And, um,

637
00:27:36.240 --> 00:27:37.840
one would be typical of,

638
00:27:39.360 --> 00:27:42.360
uh, well known types of asteroids. And the

639
00:27:42.360 --> 00:27:44.880
other, as I said, doesn't correspond to any

640
00:27:44.959 --> 00:27:47.940
kind of known, um, group of, uh,

641
00:27:49.080 --> 00:27:51.840
um, cosmic spherules or meteorites.

642
00:27:52.260 --> 00:27:54.880
Uh, and it's really quite

643
00:27:54.880 --> 00:27:57.200
remarkable that this, you know, we're being

644
00:27:57.440 --> 00:27:59.720
bombarded by dust particles that come from

645
00:27:59.720 --> 00:28:01.960
somewhere which we haven't identified.

646
00:28:02.360 --> 00:28:02.840
Professor Fred Watson: Yeah.

647
00:28:02.920 --> 00:28:05.720
Andrew Dunkley: Wow. Um, could that mean they're from

648
00:28:05.800 --> 00:28:08.400
beyond our system or it's just a part of the

649
00:28:08.400 --> 00:28:09.160
system that we.

650
00:28:11.000 --> 00:28:11.720
Professor Fred Watson: I think it's.

651
00:28:11.720 --> 00:28:12.280
Andrew Dunkley: I don't know.

652
00:28:13.320 --> 00:28:15.320
Professor Fred Watson: Yeah, I think it's the other way around. Um,

653
00:28:15.400 --> 00:28:18.000
because the m. The team who've done the

654
00:28:18.000 --> 00:28:19.960
research on this, a very, very thorough piece

655
00:28:19.960 --> 00:28:22.520
of research, they've basically,

656
00:28:23.360 --> 00:28:25.820
um, as you would, you've used, uh,

657
00:28:25.820 --> 00:28:28.280
simulations, computer simulations

658
00:28:28.760 --> 00:28:30.920
to, to essentially work out

659
00:28:31.710 --> 00:28:33.990
what conditions these things formed in when

660
00:28:33.990 --> 00:28:36.630
they, um, melted coming through the Earth's

661
00:28:36.630 --> 00:28:39.630
atmosphere. And it suggested that the best

662
00:28:39.630 --> 00:28:42.630
fit they get to what they see, the sort of

663
00:28:42.630 --> 00:28:45.470
textures that are in the material fit

664
00:28:45.470 --> 00:28:47.390
with relatively low

665
00:28:47.790 --> 00:28:50.710
velocities, uh, 14 to 17 kilometres

666
00:28:50.710 --> 00:28:52.910
per second. Uh, which is

667
00:28:53.390 --> 00:28:55.750
pretty speedy when you think of it on Earth.

668
00:28:55.750 --> 00:28:58.470
But, um, uh, in space, that's a

669
00:28:58.470 --> 00:29:00.910
fairly modest, uh, space speed for a

670
00:29:00.910 --> 00:29:02.910
meteorite that typically will be more like 30

671
00:29:03.130 --> 00:29:05.930
kilometres per second. And so that

672
00:29:05.930 --> 00:29:08.690
low value, uh, suggests

673
00:29:08.690 --> 00:29:10.730
that possibly those

674
00:29:11.050 --> 00:29:13.930
particles originated in near

675
00:29:13.930 --> 00:29:16.850
Earth asteroids, um, ones

676
00:29:16.850 --> 00:29:19.810
that are, um, following a similar path

677
00:29:19.810 --> 00:29:22.570
through space to the Earth. And that

678
00:29:22.810 --> 00:29:25.690
might mean that we've got some sort of,

679
00:29:26.190 --> 00:29:28.890
um, in the Earth's environment, some

680
00:29:28.970 --> 00:29:31.650
sort of unusual asteroid

681
00:29:31.650 --> 00:29:34.140
that is not, not matched by all the ones that

682
00:29:34.140 --> 00:29:34.780
we know already.

683
00:29:35.180 --> 00:29:35.660
Professor Fred Watson: Wow.

684
00:29:35.660 --> 00:29:37.700
Andrew Dunkley: That'd be something, uh, that's probably

685
00:29:37.700 --> 00:29:39.100
gonna be hard to track down though.

686
00:29:39.580 --> 00:29:41.460
Professor Fred Watson: Yes, yes, that's probably right. And

687
00:29:41.460 --> 00:29:43.220
especially since it might not exist anymore,

688
00:29:43.220 --> 00:29:45.300
it may have collided and formed little bits

689
00:29:45.300 --> 00:29:47.900
that have basically rained down on the Earth.

690
00:29:47.900 --> 00:29:50.860
Andrew Dunkley: Yeah. Now, it wasn't Thea. Rusty just.

691
00:29:51.180 --> 00:29:52.660
Professor Fred Watson: No, it wasn't Thea. That's right. Yeah.

692
00:29:52.660 --> 00:29:54.380
Thanks, Rusty. It's not Thea.

693
00:29:55.110 --> 00:29:57.380
Andrew Dunkley: Um, for the record, Brownlee particles and

694
00:29:57.380 --> 00:29:59.860
cosmic spherules are closely related, but

695
00:29:59.860 --> 00:30:01.420
they are not exactly the same thing.

696
00:30:01.660 --> 00:30:02.300
Professor Fred Watson: Okay.

697
00:30:02.380 --> 00:30:05.280
Andrew Dunkley: They represent two different ages or types

698
00:30:05.280 --> 00:30:06.760
of micrometeorites.

699
00:30:07.320 --> 00:30:09.720
Professor Fred Watson: There you go. Thank you for checking that.

700
00:30:10.040 --> 00:30:11.400
Yes, that's all right.

701
00:30:11.430 --> 00:30:13.080
Andrew Dunkley: Um, yeah, they're very close, but they're

702
00:30:13.080 --> 00:30:14.000
not, not the same.

703
00:30:14.000 --> 00:30:15.160
Professor Fred Watson: So I was on the right track.

704
00:30:15.240 --> 00:30:16.600
Andrew Dunkley: You were, yes.

705
00:30:17.320 --> 00:30:20.030
And you can read all about that at, uh,

706
00:30:20.279 --> 00:30:23.120
the AstroDailyPod Galaxy website. Um, and

707
00:30:23.120 --> 00:30:25.720
the article Was published where,

708
00:30:25.880 --> 00:30:27.560
Fred Watson, I've lost the science advances.

709
00:30:29.240 --> 00:30:31.170
That's right, yes. Want to read the whole

710
00:30:31.170 --> 00:30:32.770
thing before bed so you sleep well?

711
00:30:34.770 --> 00:30:35.330
Professor Fred Watson: Yep.

712
00:30:35.410 --> 00:30:35.850
Professor Fred Watson: Yeah.

713
00:30:35.850 --> 00:30:37.810
Andrew Dunkley: This is Space Nuts with Andrew Dunkley and

714
00:30:37.810 --> 00:30:38.930
Professor Fred Watson Watson.

715
00:30:40.930 --> 00:30:43.810
Professor Fred Watson: We choose to go to the moon in this decade

716
00:30:43.810 --> 00:30:46.690
and do the other things, not because they are

717
00:30:46.690 --> 00:30:49.570
easy, but because they are hard, these nuts.

718
00:30:50.850 --> 00:30:53.610
Andrew Dunkley: Our, ah, final storey today takes us

719
00:30:53.610 --> 00:30:56.250
to the edge of our galaxy. Well, it takes us

720
00:30:56.250 --> 00:30:58.130
from the centre of our galaxy right out to

721
00:30:58.130 --> 00:30:59.650
the edge of our galaxy because we're talking

722
00:30:59.650 --> 00:31:01.490
about the whole thing lock, stock and barrel.

723
00:31:02.280 --> 00:31:04.920
And it appears, Fred Watson, with some very

724
00:31:04.920 --> 00:31:07.640
clever scientific brains in action,

725
00:31:07.800 --> 00:31:10.480
that, uh, our galaxy stretches out further

726
00:31:10.480 --> 00:31:11.320
than we thought.

727
00:31:13.000 --> 00:31:15.760
Professor Fred Watson: Uh, it does. It looks as though the spiral

728
00:31:15.760 --> 00:31:17.480
arms are longer than we thought they were.

729
00:31:18.680 --> 00:31:21.360
And I think this is a very nice piece of

730
00:31:21.360 --> 00:31:23.720
work, uh, as, uh, I hinted before,

731
00:31:24.360 --> 00:31:27.200
uh, partly because it uses a technique that I

732
00:31:27.200 --> 00:31:29.840
think is really extraordinary. It's a very

733
00:31:29.840 --> 00:31:31.880
powerful technique, uh, using what we call

734
00:31:31.880 --> 00:31:34.390
light echoes. Um,

735
00:31:35.130 --> 00:31:37.650
so the storey, basically, to set this in

736
00:31:37.650 --> 00:31:40.450
context, it's very hard for us to

737
00:31:40.450 --> 00:31:42.850
produce a map of what our own galaxy looks

738
00:31:42.850 --> 00:31:45.610
like. And that's because we're embedded in

739
00:31:45.690 --> 00:31:48.690
one of the spiral arms. Uh, the

740
00:31:48.690 --> 00:31:50.690
stars that we see when we look at the Milky

741
00:31:50.690 --> 00:31:53.010
Way. They're stars that, uh, fellow

742
00:31:53.010 --> 00:31:55.050
travellers in the spiral arms with our, uh,

743
00:31:55.050 --> 00:31:57.850
sun and solar system. But they only go out to

744
00:31:57.850 --> 00:32:00.370
1000 light years or so because the spiral

745
00:32:00.370 --> 00:32:02.490
arms are so dusty that you can't really

746
00:32:02.490 --> 00:32:05.250
penetrate much beyond that. Um,

747
00:32:05.270 --> 00:32:07.750
and if you were relying only on visible

748
00:32:07.910 --> 00:32:10.710
light, uh, it would be

749
00:32:10.710 --> 00:32:13.270
like trying to draw a map

750
00:32:13.830 --> 00:32:16.470
of the whole of Dubbo from

751
00:32:16.470 --> 00:32:19.340
standing outside Dubbo jail there on, um,

752
00:32:20.250 --> 00:32:22.550
uh, forgotten. Is that Macquarie Street?

753
00:32:22.550 --> 00:32:23.670
Andrew Dunkley: Macquarie street, yeah.

754
00:32:23.670 --> 00:32:24.470
Professor Fred Watson: Yes, yes.

755
00:32:24.470 --> 00:32:26.650
Andrew Dunkley: Oh, for the record, they're putting a, um,

756
00:32:27.110 --> 00:32:28.830
they've taken down the public building in

757
00:32:28.830 --> 00:32:30.190
front of the old Dubbo jail.

758
00:32:30.190 --> 00:32:30.950
Professor Fred Watson: Oh, there you go.

759
00:32:30.950 --> 00:32:33.790
Andrew Dunkley: Now they're turning it into a public

760
00:32:33.790 --> 00:32:34.510
common. Common.

761
00:32:35.310 --> 00:32:36.430
Professor Fred Watson: I, uh, like that idea.

762
00:32:36.590 --> 00:32:38.230
Andrew Dunkley: That's going to look very nice when it's

763
00:32:38.230 --> 00:32:38.510
done.

764
00:32:39.070 --> 00:32:41.070
Professor Fred Watson: So that would improve your view of the city

765
00:32:41.070 --> 00:32:43.990
of Dubbo, but it still might not let you make

766
00:32:43.990 --> 00:32:46.640
a map of Dubbo from just there. Uh,

767
00:32:46.750 --> 00:32:48.870
and that's how we are in our galaxy. If

768
00:32:48.870 --> 00:32:51.550
you're relying on visible light observations,

769
00:32:52.190 --> 00:32:54.830
uh, all you're seeing when you look

770
00:32:55.310 --> 00:32:57.550
is the neighbourhood of, uh, our

771
00:32:57.870 --> 00:32:59.990
spiral arm, a local spiral arm. You don't get

772
00:32:59.990 --> 00:33:02.430
any hint or inclination of the structure of

773
00:33:02.430 --> 00:33:05.430
the galaxy, uh, beyond that. And in

774
00:33:05.430 --> 00:33:08.360
particular, you know, if we see

775
00:33:08.840 --> 00:33:11.080
a thousand light years or so, there's another

776
00:33:11.080 --> 00:33:12.760
Hundred thousand that we're not seeing

777
00:33:12.760 --> 00:33:14.480
because that's about the diameter of, ah, our

778
00:33:14.480 --> 00:33:17.040
galaxy. So, um, ah, the

779
00:33:17.040 --> 00:33:19.980
situation improves when you use infrared, uh,

780
00:33:20.520 --> 00:33:22.770
radiation. You can sort of penetrate, uh,

781
00:33:23.160 --> 00:33:25.880
through the dust and see actually the centre,

782
00:33:25.880 --> 00:33:27.760
towards the centre of our galaxy. That's how

783
00:33:27.760 --> 00:33:30.040
we know about the black hole in the centre of

784
00:33:30.040 --> 00:33:31.680
our galaxy, because we could see stars

785
00:33:31.680 --> 00:33:34.380
orbiting around it. Um, but

786
00:33:34.380 --> 00:33:37.380
it improves even more on a broader scale if

787
00:33:37.380 --> 00:33:39.460
you can use radio telescopes, because you can

788
00:33:39.460 --> 00:33:42.460
plot, um, where the clouds of

789
00:33:42.460 --> 00:33:45.460
hydrogen gas called hydrogen, uh, which

790
00:33:45.700 --> 00:33:48.380
radiates in, uh, radio waves, uh, with a

791
00:33:48.380 --> 00:33:51.260
wavelength of 21 centimetres, uh, that you

792
00:33:51.260 --> 00:33:53.140
can plot out. But if you're going to try and

793
00:33:53.140 --> 00:33:55.700
draw a map, you do need to do some modelling

794
00:33:55.700 --> 00:33:57.380
with that. You've got to assume things about

795
00:33:57.380 --> 00:33:59.740
the rotation of the galaxy so it doesn't just

796
00:33:59.740 --> 00:34:02.660
give you a direct map, map. And that could

797
00:34:02.660 --> 00:34:04.900
be wrong. We could have that little bit of it

798
00:34:04.900 --> 00:34:07.900
wrong, uh, you know, uh, the stuff that comes

799
00:34:07.900 --> 00:34:10.820
from the radio observations. So

800
00:34:10.820 --> 00:34:13.660
what's happened now is it's a

801
00:34:13.660 --> 00:34:16.580
team, uh, I think they're based in Italy,

802
00:34:16.780 --> 00:34:19.780
uh, and what they've done

803
00:34:19.940 --> 00:34:22.360
is used, um,

804
00:34:23.300 --> 00:34:26.140
a direct method of kind of

805
00:34:26.140 --> 00:34:29.020
setting up a standard ruler. Uh, because if

806
00:34:29.020 --> 00:34:30.700
you've got a standard ruler and you can see

807
00:34:30.700 --> 00:34:32.730
it in deep space, then you know how far away

808
00:34:32.959 --> 00:34:34.999
it is because you can measure how long it

809
00:34:34.999 --> 00:34:37.039
appears to be. And if you know how long it

810
00:34:37.039 --> 00:34:39.559
is, which is what a standard ruler is, then

811
00:34:39.559 --> 00:34:42.559
you know how far away it is. And that's

812
00:34:42.559 --> 00:34:45.199
what they're doing. They have. And it goes

813
00:34:45.199 --> 00:34:47.479
back to something we mentioned earlier in the

814
00:34:47.479 --> 00:34:49.999
show, gamma ray bursts. These bursts of gamma

815
00:34:49.999 --> 00:34:52.399
radiation, those

816
00:34:52.399 --> 00:34:55.399
bursts, uh, don't just directly come to

817
00:34:55.399 --> 00:34:57.959
us, they also bounce off or are

818
00:34:57.959 --> 00:35:00.830
reflected by clouds of dust in our

819
00:35:00.830 --> 00:35:03.830
spiral arms. And, uh, so

820
00:35:04.310 --> 00:35:07.110
by timing how long,

821
00:35:07.710 --> 00:35:10.510
uh, it takes for these echoes, as

822
00:35:10.510 --> 00:35:12.630
they're called, light echoes, even though

823
00:35:12.630 --> 00:35:15.550
it's gamma radiation, uh, to what

824
00:35:15.550 --> 00:35:18.030
the delay is between a light

825
00:35:18.030 --> 00:35:21.030
echo and the, uh, source itself,

826
00:35:21.030 --> 00:35:22.750
which is the gamma ray burst, I should say

827
00:35:22.750 --> 00:35:24.710
they probably come from collapsing

828
00:35:25.510 --> 00:35:27.990
massive stars or merger of neutron

829
00:35:27.990 --> 00:35:30.870
stars, uh, very energetic events

830
00:35:31.010 --> 00:35:32.930
because they're bright in gamma radiation.

831
00:35:33.330 --> 00:35:36.130
But if you look at a light echo from a gamma

832
00:35:36.130 --> 00:35:38.850
ray burst, it gives you a scale to this,

833
00:35:39.010 --> 00:35:41.250
you know, um, how far.

834
00:35:42.850 --> 00:35:44.770
Basically, uh, it gives you a standard ruler,

835
00:35:44.840 --> 00:35:47.370
um, because you can time it accurately, you

836
00:35:47.370 --> 00:35:50.090
know that 300,000 kilometres per second is

837
00:35:50.090 --> 00:35:52.490
the speed of gamma rays through space. And,

838
00:35:52.490 --> 00:35:54.730
you know, if you know how far away it's gone

839
00:35:54.730 --> 00:35:56.610
in that time, then that gives you a distance

840
00:35:56.610 --> 00:35:59.220
measure. So you've got a standard ruler. Uh,

841
00:35:59.250 --> 00:36:01.490
it's a very, very nice way of doing this.

842
00:36:01.490 --> 00:36:04.230
And, um, using that, uh, these,

843
00:36:04.440 --> 00:36:07.390
uh, scientists, um, as I

844
00:36:07.390 --> 00:36:10.000
said, uh, at least the lead author is, uh,

845
00:36:10.000 --> 00:36:12.870
certainly in Italy at ENAF in Milano,

846
00:36:13.160 --> 00:36:16.070
uh, uh, they've done this work

847
00:36:16.150 --> 00:36:18.430
looking at these gamma ray bursts with their

848
00:36:18.430 --> 00:36:20.750
light echoes, and that allows them to

849
00:36:20.750 --> 00:36:23.720
calculate basically the size of our, uh,

850
00:36:23.720 --> 00:36:26.110
spiral arms without relying on any kind of

851
00:36:26.110 --> 00:36:28.910
modelling. And so

852
00:36:28.910 --> 00:36:31.590
they think that the new

853
00:36:31.590 --> 00:36:34.570
observations indicate that, uh, our spiral

854
00:36:34.570 --> 00:36:36.610
arms are something like 10%

855
00:36:37.170 --> 00:36:39.410
longer than we thought they were. Wow,

856
00:36:39.410 --> 00:36:39.740
that's, uh.

857
00:36:39.740 --> 00:36:40.050
Professor Fred Watson: A lot.

858
00:36:40.450 --> 00:36:42.890
Professor Fred Watson: Yes. That's significant, isn't it? It's

859
00:36:42.890 --> 00:36:45.250
really, um. You know, this is. As I said,

860
00:36:45.250 --> 00:36:47.490
this is very nice, uh, nice astronomy.

861
00:36:48.050 --> 00:36:50.810
Andrew Dunkley: It is indeed. Yeah. Um, of

862
00:36:50.810 --> 00:36:53.410
course, as you say, we can't really look at

863
00:36:53.410 --> 00:36:55.770
our galaxy. We don't know exactly what it

864
00:36:55.770 --> 00:36:57.810
looks like. Um, there's a lot of science that

865
00:36:57.810 --> 00:37:00.750
they've put together to try and create

866
00:37:00.750 --> 00:37:02.870
the image of it. And even in this particular

867
00:37:03.030 --> 00:37:05.350
storey, uh, which is in the Universe Today

868
00:37:05.430 --> 00:37:07.670
dot com, they've got an artist's impression

869
00:37:07.670 --> 00:37:10.550
of what this new, uh, look is like.

870
00:37:10.550 --> 00:37:11.830
Professor Fred Watson: Yes. That's all you can do.

871
00:37:11.910 --> 00:37:14.470
Andrew Dunkley: Reminds me of an upside down snail.

872
00:37:15.750 --> 00:37:18.430
Professor Fred Watson: It does, yes, that's right. I see what you

873
00:37:18.430 --> 00:37:19.350
mean. Yes, yes.

874
00:37:22.150 --> 00:37:24.470
Andrew Dunkley: Or a squid. Could be a squid.

875
00:37:24.470 --> 00:37:25.830
Professor Fred Watson: Could be a squid, yeah.

876
00:37:26.430 --> 00:37:29.190
Andrew Dunkley: Uh, but in real terms we just have

877
00:37:29.190 --> 00:37:32.090
to. It's an edge. Very, very educated

878
00:37:32.090 --> 00:37:33.010
guess, I suppose.

879
00:37:33.950 --> 00:37:36.930
Professor Fred Watson: Um, yes, it is. It's a measurement.

880
00:37:37.170 --> 00:37:40.090
So you're right,

881
00:37:40.090 --> 00:37:41.530
it's an artist's impression. That's really

882
00:37:41.530 --> 00:37:43.730
the only way we can depict the Milky Way.

883
00:37:43.970 --> 00:37:45.650
Some of the depictions are very, very good

884
00:37:45.650 --> 00:37:47.810
and they rely on the very best radio and

885
00:37:47.810 --> 00:37:50.130
infrared observations that have been made.

886
00:37:50.210 --> 00:37:52.690
But this is going to modify it a little bit

887
00:37:52.690 --> 00:37:55.530
by our new knowledge of the spiral arms. And

888
00:37:55.530 --> 00:37:58.060
I should say, um, this, the, um.

889
00:37:58.480 --> 00:38:01.300
It's the Chandra satellite, uh, which is a,

890
00:38:01.300 --> 00:38:04.230
ah, an X ray observatory, um,

891
00:38:04.240 --> 00:38:07.180
by. Operated by NASA, uh,

892
00:38:07.200 --> 00:38:09.680
that has been used to make the measurements.

893
00:38:10.080 --> 00:38:13.000
And I do like the headline on a little, uh,

894
00:38:13.000 --> 00:38:15.040
NASA video that there is Here, which is

895
00:38:15.040 --> 00:38:17.920
NASA's Chandra examines Milky Way at

896
00:38:17.920 --> 00:38:18.720
Arm's Length.

897
00:38:18.720 --> 00:38:21.680
Andrew Dunkley: Yeah, nice. Um, very

898
00:38:21.680 --> 00:38:22.240
well done.

899
00:38:22.240 --> 00:38:25.200
Professor Fred Watson: Clever, clever. Yeah, they are.

900
00:38:25.200 --> 00:38:26.160
There's some good people there.

901
00:38:26.160 --> 00:38:28.960
Andrew Dunkley: Uh, so the articles in Universe Today, but

902
00:38:28.960 --> 00:38:31.640
you can read it in a deeper form

903
00:38:31.800 --> 00:38:34.660
through the NASA website or the, uh,

904
00:38:35.000 --> 00:38:37.160
Astronomy and Astrophysics Journal, I think,

905
00:38:37.160 --> 00:38:39.560
has published, uh, the full paper, which is.

906
00:38:40.120 --> 00:38:42.680
Professor Fred Watson: Yeah, that's the European journal.

907
00:38:43.000 --> 00:38:45.920
Andrew Dunkley: Lots of numbers in it. Yeah, lots and

908
00:38:45.920 --> 00:38:48.800
lots of numbers. Numbers that are too big

909
00:38:48.800 --> 00:38:49.640
for my brain.

910
00:38:51.880 --> 00:38:54.600
All right, uh, that's where we end the show.

911
00:38:54.600 --> 00:38:55.630
Fred Watson, thank you very much.

912
00:38:55.780 --> 00:38:56.020
Professor Fred Watson: Much.

913
00:38:56.100 --> 00:38:58.660
Professor Fred Watson: Oh, a pleasure. Uh, as you said at the

914
00:38:58.660 --> 00:38:59.980
beginning, some nice storeys there.

915
00:38:59.980 --> 00:39:01.460
Andrew Dunkley: Yeah. I'm very glad to be able to

916
00:39:01.460 --> 00:39:02.260
Professor Fred Watson: share them with you.

917
00:39:02.260 --> 00:39:04.660
Andrew Dunkley: Indeed. Uh, we'll catch you real soon. Thank

918
00:39:04.660 --> 00:39:05.060
you, Fred Watson.

919
00:39:05.380 --> 00:39:06.660
Professor Fred Watson: No worries. Thanks, Andrew.

920
00:39:06.660 --> 00:39:08.460
Andrew Dunkley: Professor Fred Watson Watson, astronomer at

921
00:39:08.460 --> 00:39:10.660
large, and, uh, as I say, between episodes,

922
00:39:10.660 --> 00:39:13.500
Visit our website, spacenutspodcast.com or

923
00:39:13.500 --> 00:39:16.100
spacenuts IO if you're a lazy

924
00:39:16.100 --> 00:39:18.820
typist and you can have a look around,

925
00:39:18.820 --> 00:39:21.540
visit our shop. Uh, sign up for the Astronomy

926
00:39:21.540 --> 00:39:23.260
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927
00:39:23.260 --> 00:39:25.420
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928
00:39:25.420 --> 00:39:28.240
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929
00:39:28.320 --> 00:39:30.320
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930
00:39:30.320 --> 00:39:33.080
forget to leave reviews of Space Nuts, your

931
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favourite podcasting platform. And thanks to

932
00:39:35.320 --> 00:39:37.960
Huw in the studio because he didn't turn up

933
00:39:37.960 --> 00:39:40.560
today. And from me, Andrew Duckling. Whoops.

934
00:39:40.720 --> 00:39:42.320
Uh, thanks for your company. We'll catch you

935
00:39:42.320 --> 00:39:44.640
on the next episode of Space Nuts. Bye. Bye.

936
00:39:45.920 --> 00:39:48.120
You've been listening to the Space Nuts

937
00:39:48.120 --> 00:39:51.080
podcast, available at

938
00:39:51.080 --> 00:39:53.040
Apple Podcasts, Spotify,

939
00:39:53.460 --> 00:39:56.340
iHeartRadio or your favourite podcast player.

940
00:39:56.420 --> 00:39:59.380
You can also stream on demand@bytes.um.com.

941
00:39:59.700 --> 00:40:01.780
Professor Fred Watson: this has been another quality podcast

942
00:40:01.780 --> 00:40:03.940
production from bytes.um.com.