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

An episode of [Space Nuts: Astronomy Insights & Cosmic Discoveries](https://invisiblenetwork.ai/podcast/1080090608), 1 Aug 2026, 42 min.

Audio: https://dts.podtrac.com/redirect.mp3/pscrb.fm/rss/p/op3.dev/e/api.spreaker.com/download/episode/73304496/spacex_tests_space_ready_nuclear_power_using_tritium_driven_cubesat_nordvpn.mp3

Sponsor Link: NordVPN - Safeguard your online activity with our exclusive offer for Space Nuts listeners. Visit www.nordvpn.com/spacenuts for details. From SpaceX Nuclear Experiments to Galactic Discoveries Join host Andrew Dunkley and astronomer Fred Watson as they explore some of the most fascinating topics in space science, from innovative nuclear power tests in space to the expanding boundaries of our galaxy. Whether you're an astrophotography enthusiast or a space policy advocate, this episode delivers insights that broaden your cosmic perspective. In this episode: SpaceX's recent CubeSat launch featuring a tritium-based nuclear power source for space applications The potential and safety considerations of nuclear energy in space missions The possibility of nuclear weapons detection in space using neutron sensors and passive radiation monitoring The intriguing hypothesis of dark matter stars and their potential signatures The mystery surrounding Earth's dust origins—cosmic spherules and their unknown sources New research indicating our galaxy's spiral arms are about 10% longer than previous estimates, based on light echoes from gamma ray bursts The rise of smart telescopes and their role in making astrophotography more accessible for amateurs Timestamps: (00:00) Introduction and overview of today's headlines (02:00) SpaceX's CubeSat with tritium power source—what's happening? (04:33) Nuclear power in space: Safety and future applications (11:03) Detecting nuclear weapons in space: Challenges and innovations (22:45) Earth's dust origins: Micro-meteorites and cosmic spherules explained Resources & Links: SpaceX's CubeSat nitrogen launch story Beta-voltaic nuclear power technology NASA's Chandra X-ray Observatory Universe Today article on Milky Way mapping James Webb Space Telescope and dark matter research Science Advances publication on Earth's micrometeorites Connect with Fred Watson: LinkedIn Twitter Enjoying the show? Support us on Patreon and leave a review on your favorite podcast platform. Thanks for tuning in and keep looking up! Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support.

## Transcript

[0:00] Professor Fred Watson: Hi there.
[0:00] Andrew Dunkley: Thanks again for joining us. This is Space
[0:02] Nuts. My name is Andrew Dunkley and every
[0:05] week we talk astronomy and space science
[0:08] and we answer audience questions in our
[0:10] alternative show, which, uh, happens,
[0:13] um, well, wherever you are. I mean, we
[0:16] release it on a Monday, but that doesn't mean
[0:17] you listen to it on a Monday. Uh, coming up
[0:20] today we've got, uh, a couple of
[0:23] nuclear explosive storeys. Uh,
[0:26] SpaceX is involved in one of those and
[0:29] the other storey is about, uh, blowing things
[0:31] up with atomic weapons from space.
[0:34] Yes, highly guaranteed. Very, very, uh,
[0:36] effective as well. Uh, but I think there's
[0:39] probably a reason not to. We'll look at all
[0:41] of that. Uh, we're also going to talk about
[0:44] where Earth's, uh, dust came from. Quite a
[0:47] bit of it, which might come as a bit of a
[0:48] surprise. Uh, you just have to look under
[0:50] just about every bed and kitchen table in the
[0:53] world to find as much dust as there is in the
[0:55] world. But we'll see where that, uh, is
[0:58] headed. And our galaxy, uh, reaches
[1:00] out further than we thought. Apparently, uh,
[1:03] there's some interesting science behind that.
[1:05] We'll talk about it all on this edition of
[1:08] space nuts.
[1:09] Professor Fred Watson: 15 seconds. Guidance is internal.
[1:11] 10, 9. Ignition
[1:14] sequence start.
[1:15] Professor Fred Watson: Space nuts.
[1:16] Professor Fred Watson: 5, 4, 3, 2. 1, 2, 3, 4,
[1:19] 5, 5, 4, 3, 2, 1.
[1:21] Andrew Dunkley: Space nuts.
[1:22] Professor Fred Watson: Astronauts report it feels good.
[1:25] Andrew Dunkley: And joining us again to talk about all of
[1:27] that and more is Professor Fred Watson
[1:29] Watson, astronomer at large. Hello,
[1:31] Fred Watson.
[1:32] Professor Fred Watson: Hello, Andrew. Good to see you. Good to see
[1:34] you. Yes.
[1:35] We sort of missed a few days, haven't we?
[1:38] Yes.
[1:40] Andrew Dunkley: Uh, you've been off conferencing.
[1:41] Professor Fred Watson: Yes. So the annual science meeting,
[1:44] as it's called, of the National Astronomy
[1:47] Society, the Astronomical Society of
[1:48] Australia, it's where all the professional
[1:50] astronomers get together and, uh, talk about
[1:53] what they've been doing, their research. Uh,
[1:55] it was a big meeting. There were, I would
[1:58] have guessed, maybe a couple of hundred
[2:01] people there altogether. Uh, that's quite big
[2:03] for astronomers in a country that's only got
[2:05] 700 astronomers in it.
[2:07] Professor Fred Watson: Yeah.
[2:08] Professor Fred Watson: Uh, but, um, what was interesting and
[2:10] what was very, I think,
[2:13] heartening for me was the number of
[2:16] youngsters that were there. I call them
[2:17] youngsters, you know, people under 50
[2:20] people, um, the new generation of
[2:23] astronomers, uh, most of them whom I didn't
[2:26] know and they've no idea who I am, and that's
[2:28] fine. Uh, that all was okay. It
[2:31] just contrasts with a few years ago. So when
[2:33] I was the astronomer in charge of the
[2:35] observatory at, uh, Coonabarabran, uh,
[2:39] we were kind of the Shopkeepers. So all these
[2:41] astronomers used to come through, stay in the
[2:43] lodge and do their research using the
[2:45] telescope. So I knew a large fraction of
[2:48] the astronomical population of Australia. But
[2:50] that's changed, uh, because my job,
[2:53] that job is no longer mine. Uh,
[2:56] and so I don't see people the same way. But
[2:59] it was very nice to meet a lot of new faces
[3:02] and catch up with some very old faces as
[3:04] well, some even older than mine. Um, and we
[3:07] also discussed matters such as the future
[3:10] of Australian astronomy because that's
[3:12] uh, in a interesting
[3:15] state at the moment. With the government
[3:17] having declined, uh, to
[3:20] engage in membership with the European
[3:23] Southern Observatory. We are now working on
[3:25] plan B. Uh, and um. Well, it looks
[3:27] promising.
[3:28] Andrew Dunkley: Yes, fingers crossed. A lot going on.
[3:31] Okay, um, we should probably get
[3:34] stuck into these storeys because there's a
[3:36] lot to discuss. The first storey is a double
[3:38] banger about nuclear, um, energy and
[3:41] atomic weapons.
[3:43] Uh, we'll start off with the storey about
[3:45] SpaceX. And
[3:48] um, they're looking at nuclear power
[3:50] in space, nuclear powered satellites. What's
[3:53] the storey here?
[3:54] Professor Fred Watson: It's a test launch, really. A launch of
[3:58] a cubesat basically that um,
[4:01] has not a nuclear reactor inside but
[4:04] um, basically a capsule of something called
[4:07] tritium which is sometimes called heavy
[4:09] hydrogen. It's hydrogen with two
[4:11] electrons in it as well as the proton at uh,
[4:14] its centre. And it's radioactive. Uh,
[4:17] tritium is um, I suppose you'd call it
[4:20] mildly radioactive. Um, we used to
[4:22] use tritium standard lamps at the
[4:25] observatory when I was working there, which
[4:28] was a little capsule of tritium with some
[4:30] phosphor on it. Um, and
[4:33] um, basically the electrons released by the
[4:36] tritium lit up the phosphor and
[4:38] gave a very constant glow so we could use it
[4:41] to calibrate other, other instruments.
[4:44] So I've been close up and personal with um,
[4:47] a little nuclear power source a bit like
[4:49] that, but it was just making faint light.
[4:52] This one is one that's been uh,
[4:54] developed by a private company. Um,
[4:57] and it's uh, basically a
[5:00] company called City Labs, uh, in the United
[5:03] States. Uh, they've built
[5:05] um, a little, as I said, it's
[5:08] effectively a cubesat which has this um,
[5:11] little nuclear, not nuclear
[5:14] reactor, but nuclear power source inside a
[5:16] tritium, uh, source that I've just been
[5:19] talking about, which doesn't actually convert
[5:21] the electrons into light, it
[5:24] converts them directly into electricity.
[5:27] So they've got these panels on the side of it
[5:30] that take the electrons that come from the
[5:32] tritium and turn them straight into
[5:35] um, electricity. Ah, it's
[5:38] Called Bohr B O H R, uh, which is
[5:40] a bit of a play on words because Niels Bohr
[5:43] was one of the great founders of quantum
[5:45] theory. Same spelling, um
[5:48] Danish one, A uh, Danish uh
[5:50] scientist, uh and it stands for
[5:53] Beta Voltaic. And a
[5:55] Beta Voltaic is taking the beta particles,
[5:58] which are otherwise known as electrons, uh
[6:01] turning them into electricity. So it's Beta
[6:03] Voltaic orbital high reliability
[6:06] spacecraft. That's where you get the Bohr
[6:08] from and it's been launched. Uh,
[6:11] so SpaceX's part in this storey is just to
[6:14] provide the taxi, uh up into um, up
[6:17] into orbit. It's a transporter, uh
[6:19] mission, um, basically
[6:22] one of uh, SpaceX's taxi rides to get stuff
[6:25] up and down from uh, or up to orbit,
[6:28] coming down to different storey and most of
[6:30] them just burn up.
[6:32] Professor Fred Watson: Yes.
[6:32] Professor Fred Watson: Uh, but it is uh, probably the
[6:34] first CubeSat to include a nuclear
[6:37] power system. Uh and
[6:40] maybe, just maybe we'll sort of illuminate
[6:43] the way for a new generation of uh,
[6:46] spacecraft which are equipped with uh,
[6:48] these nuclear power sources.
[6:50] Andrew Dunkley: I suppose they have to look at alternatives
[6:53] because we've been reliant, fairly
[6:55] reliant anyway on solar energy in
[6:58] space, um particularly with our uh, orbiting
[7:01] satellites, but also with um, the
[7:04] International Space Station and others. Um,
[7:07] but the time will come where we are
[7:10] in places where there won't be that
[7:13] much sunlight and
[7:16] in some places there won't be any at all. And
[7:18] solar panels are going to be useless.
[7:21] Professor Fred Watson: Uh, that's correct. And we've seen already
[7:23] um, the use of these UH RTGs,
[7:26] radioisotope thermoelectric
[7:29] generators, uh which are carried by both
[7:32] the Curiosity and the uh
[7:34] Perseverance rovers, uh as well as
[7:37] spacecraft in deep space like uh,
[7:40] Voyager 1, Voyager 2, Pioneers. I think
[7:43] they've got them as well. And these are
[7:45] spacecraft that are so far from the sun that
[7:47] you get very little light from the sun,
[7:50] uh in terms of um, you know, using it to
[7:52] generate electricity. So they've, they've had
[7:54] their nuclear power sources for a long time.
[7:57] They are quite different though from what
[7:58] we're talking about here. There are, I think
[8:00] it's 13 kilogrammes if I remember rightly, is
[8:02] the amount in a canister of plutonium
[8:05] dioxide, uh which is
[8:07] decaying all the time and getting very hot as
[8:10] it does that and that heat is then used
[8:13] to generate electricity, uh and
[8:17] it actually dies away as time goes on. So
[8:19] these nuclear uh, RTGs, the
[8:22] radioisotope thermoelectric generators
[8:25] gradually lose their power, um, and that's
[8:28] why we hear from time to time and we usually
[8:30] report this on space nuts. We hear of
[8:33] uh, uh instruments on board Voyager 1
[8:36] being turned off to save the power.
[8:39] Andrew Dunkley: Yeah. And that happened again not so long
[8:42] ago.
[8:42] Professor Fred Watson: I think that's correct. Yes it did.
[8:45] There was one turned off uh quite recently
[8:47] but perhaps more to the point and
[8:50] uh, what you've just said about there being
[8:52] some places that have no sunlight whatsoever,
[8:54] uh that applies to uh, those deep
[8:57] craters near the moon's south pole
[9:00] and that's where we're thinking of exploring.
[9:03] So it may be that um, these
[9:06] beta voltaic arrays
[9:09] uh uh, or devices might well
[9:12] be the future of power generation
[9:15] near the moon's south pole because you're in
[9:17] places where there's no light whatsoever from
[9:20] the sun.
[9:20] Andrew Dunkley: That's absolutely true. Darn cold too. It is.
[9:23] Professor Fred Watson: It is always cold there. Yes, yes
[9:26] indeed.
[9:27] Andrew Dunkley: Uh, uh that's a really interesting storey and
[9:30] we're obviously in the early phases of
[9:32] finding these alternatives. Is um, tritium
[9:35] safe?
[9:36] Professor Fred Watson: Uh, it's probably something regarded
[9:39] uh, treated carefully.
[9:43] It is generally safe. I mean we never took
[9:46] any real precautions with the device that we
[9:48] had on the telescope. Maybe we should
[9:51] have done. Although uh, most of
[9:54] us are still around and in fairly good
[9:56] health. But um, yes they are
[9:59] releasing electrons, uh beta radiation,
[10:02] uh, it's um, uh if you had a
[10:05] high level though of tritium, if you had a
[10:08] significant amount of it then you would have
[10:10] to be careful about how you handled it and
[10:12] where it was put and if it needed shielding
[10:14] and things of that sort.
[10:15] Andrew Dunkley: Yeah. So uh, don't sprinkle it on your
[10:17] cornflakes or anything like that.
[10:18] Professor Fred Watson: Yes, that's right. It's best to avoid it if
[10:20] you can.
[10:21] Andrew Dunkley: Yeah. Sugar's damaging enough already.
[10:25] Professor Fred Watson: It is. Tell my dentist about it.
[10:27] Andrew Dunkley: If you'd like to um, read up on that storey
[10:30] about the uh, the launch of the cubesat with
[10:32] the tritium nuclear ah power device
[10:35] they're testing. Uh you can read about
[10:37] it@dailygalaxy.com.
[10:41] um, let's keep on this theme
[10:43] Fred Watson, because that's the good news.
[10:45] Uh the bad news is um,
[10:49] the the problem of exploding nuclear
[10:51] devices in space or firing nuclear
[10:54] devices from space to targets on Earth.
[10:56] That's, that's a real issue. I know.
[10:59] Um, was it back in the 80s the
[11:02] Star wars um
[11:05] um push was uh, all the rage in the news
[11:08] at the time and uh, that got shut down pretty
[11:10] quickly.
[11:12] Professor Fred Watson: Star wars was um, a
[11:14] Reagan era initiative. Yes, I think it was, I
[11:17] think it was um, uh basically
[11:20] electromagnetic Radiation to zap your
[11:22] satellites. It wasn't nuclear though, uh,
[11:24] because nuclear weapons are in space, are
[11:27] prohibited by the outer Space Treaty
[11:30] 1967.
[11:31] Andrew Dunkley: So what's happening?
[11:32] Professor Fred Watson: They're not allowed. But,
[11:35] um, there may be some there
[11:38] launched by powers that
[11:42] stretch um, the envelope, if I can put it
[11:44] that way. Governments that stretch the
[11:46] envelope. And uh, we don't know. We don't
[11:49] know if there are any. You know, they're
[11:51] banned by the uh, Outer Space Treaty. So
[11:54] there shouldn't be any nuclear weapons in
[11:57] space. But that's all very well.
[12:00] Professor Fred Watson: Um.
[12:01] Professor Fred Watson: There's a lot of things that shouldn't happen
[12:03] but do happen. And um. So it may be
[12:05] that perhaps there are nuclear weapons in
[12:07] space. So the question is,
[12:11] um, how do you detect them if there are,
[12:13] ah, these weapons? Um,
[12:16] and um, that's
[12:20] where this piece of research, uh, from
[12:23] the Massachusetts Institute of Technology
[12:26] has come from. It's um, a um, person
[12:29] whose name is Areg Dana
[12:31] Gulian. Sounds uh, like an Armenian name.
[12:34] Does that usually I a n on the end. Armenian.
[12:37] An associate professor of nuclear science and
[12:39] engineering at the Massachusetts Institute of
[12:42] Technology. And he has
[12:45] um, essentially
[12:47] thought of a neat way,
[12:52] uh, of building a device that
[12:55] you could fly in the vicinity
[12:58] of a satellite to detect whether
[13:01] it is carrying nuclear weapons.
[13:04] Um, and it's all about the subatomic
[13:07] particles, uh, that um, you know,
[13:10] that, that nuclear um,
[13:13] weapons are all about. It's all about uh,
[13:16] neutrons and uh, you know, the nuclear
[13:18] nuclei of atoms. That's where it all comes
[13:20] from. Um, so
[13:25] what he has suggested, and I might
[13:27] quote, um,
[13:30] I might quote from uh, Dr. Dana
[13:33] Gulian's work. Uh
[13:36] the risk is that
[13:39] if you did explode a nuclear weapon in
[13:42] low Earth orbit, then you basically wreck low
[13:45] Earth orbit for everybody. It's not the
[13:47] blast, it's just the subatomic particles that
[13:50] do it. Uh, and so what he goes on to say
[13:53] is this danger is compounded by the lack
[13:56] of a verification mechanism for the Outer
[13:58] Space Treaty. Um,
[14:01] there's no detection methodologies that have
[14:04] been proposed in the scientific literature.
[14:06] So what he's saying is here's a concept and
[14:09] feasibility study, um, for
[14:11] verifying a satellite's compliance
[14:14] to the Outer Space Treaty by observing
[14:17] the neutrons induced by spallation
[14:20] from the approximately
[14:23] giga electron volt protons in the
[14:26] Innovant Allen radiation belts, which is
[14:28] a slightly complicated and technical way of
[14:31] saying, uh, you've already got subatomic
[14:34] particles in the radiation belts around
[14:37] our planet. Um, if you can,
[14:41] um, basically watch the way,
[14:44] um, a satellite responds
[14:47] to those protons that are in the radiation
[14:50] belts. Um, if for example that uh,
[14:53] bombardment of protons from the radiation
[14:55] belts causes neutron neutrons to be
[14:58] uh, emitted then you can
[15:01] have a fair degree of
[15:04] um, confidence that there might be a nuclear
[15:06] weapon on board or a lot of nuclear fissile
[15:08] material, heavy elements like uranium.
[15:11] That's the kind of thing that this is all
[15:14] about. And so um,
[15:18] uh, what this is all
[15:21] about is building uh, a
[15:23] satellite that can detect
[15:26] uh, neutrons uh, coming
[15:29] from radioactive material. And
[15:33] he's basically suggesting a
[15:35] detector, uh, uh, uh, what
[15:38] he calls an inspector satellite that flies
[15:41] by, uh, the satellite that you're
[15:44] interested in finding out whether it's got
[15:46] nuclear weapons. And it's got these detectors
[15:49] uh, which are almost like X ray detectors.
[15:51] The kind of things that you see now when you
[15:54] go for an X ray, a chest X ray. They're
[15:56] electronic, they're not photograph they used
[15:58] to be back in the day. Um, and they've got
[16:01] what are called neutron sensors, uh they're
[16:03] called scintillators. And uh, you
[16:06] put those in a special arrangement with
[16:09] other basically other detectors.
[16:12] Uh, and um, if you do that then
[16:15] you can apparently sort out the
[16:18] neutrons from the other natural
[16:21] subatomic particles that are floating around
[16:23] near the radiation belts. And the neutrons
[16:26] come from radioactive material and you can
[16:28] also see the direct direction that they're
[16:30] coming from. So you can sort of point this
[16:33] thing towards your target satellite, uh, the
[16:35] one that you suspect might have nuclear
[16:37] weapons and it will give you the direction of
[16:39] where it's coming from. Um, and
[16:42] so uh, just a quote,
[16:45] um again from Dr. Dana
[16:48] Gulian. Um, the calculations show
[16:51] that a nine unit cubesat size
[16:54] detection platform, that's something the size
[16:56] of, what's that, about three loaves of bread?
[16:58] Something of that sort size. It's quite
[17:00] small. Um, it can identify a
[17:03] thermonuclear weapon from a distance of
[17:06] four kilometres in approximately one
[17:09] week of observation. Now that's quite a long
[17:12] time but uh, apparently
[17:15] if you could get it to within one kilometre
[17:17] it would take you about an hour to detect a
[17:20] weapon. And that's
[17:23] promising. That's one flyby, that's you know,
[17:26] an hour of proximity, uh, you could do that
[17:29] as you go past the
[17:32] suspect satell. If you got an hour in
[17:35] close uh, contact with it or close uh,
[17:38] proximity to it within a
[17:40] kilometre, uh, then you might well
[17:43] detect a nuclear weapon on board. And of
[17:45] course you could improve that if you had more
[17:47] than one of these inspector satellites. If
[17:49] you multiplied them up, then you could get,
[17:51] uh, quite significant improvements in that
[17:53] performance. So it's really quite
[17:56] interesting. Um, uh, one
[17:58] quote that I really liked, um,
[18:02] and I'm going to read, uh,
[18:04] from, uh. Universe Today has a very nice
[18:07] article on this. The last sentence is, right
[18:09] now, nations like the USA and Russia rely on
[18:12] intelligence to know what the other is doing.
[18:14] And as we know from history, intelligence can
[18:17] get things wrong. You can fake intelligence,
[18:20] said Dr. Dana Gulian, but you can't fake
[18:23] physics. I like that. Yeah, it's true. So
[18:26] you could do it by physics. Yeah.
[18:28] Andrew Dunkley: They do, uh, mention in this particular
[18:31] article that there's one suspect satellite
[18:33] that seems to have been launched by Russia.
[18:35] And the bottom line is that it's
[18:38] been put in an orbit that is very strange
[18:42] and very hostile in terms
[18:45] of its radiation, uh, in that area.
[18:47] And the question is asked. Well, it says no
[18:50] one puts satellites there because it's highly
[18:52] radioactive. Why would you put a satellite in
[18:55] that orbit? So that's one they've already.
[18:58] They haven't identified as maybe carrying a
[19:01] nuclear weapon, but they've certainly
[19:03] identified it as suspicious.
[19:05] Professor Fred Watson: Yes, that's correct. And so, um.
[19:08] Yes, highlighting that, I think, you know,
[19:10] puts this article in context. It
[19:12] tells you that this is a real issue and, um,
[19:14] we kind of need to work on how you might
[19:17] detect, uh, nuclear weapons in space.
[19:19] Andrew Dunkley: Of course, the other side of it is if you do
[19:22] identify a satellite that's carrying a
[19:24] nuclear weapon, what do you do next?
[19:27] It's like trying to teach people not to
[19:29] overtake emerging lanes, isn't it?
[19:31] Professor Fred Watson: Uh, yes. Uh, but,
[19:34] uh, it's worse than that really, because. A
[19:37] little bit, yeah, you know, we have
[19:39] nations that completely disregard
[19:41] international law. They invade other
[19:44] countries without so much as a,
[19:47] you know, a sniff of the,
[19:50] um, um. Of the, um.
[19:53] All the international treaties, they just,
[19:55] Just run amok among them and away they go.
[19:58] Uh, and yes, so that's the possibility that,
[20:01] uh, we might already have them.
[20:02] There is a kind of
[20:05] corollary of this which I was thinking of
[20:07] when I read this, Storey. Um, and
[20:10] that is that back in the 70s,
[20:13] uh, gamma ray
[20:16] satellites were launched,
[20:18] satellites that detect gamma radiation. And
[20:21] that was to detect any in
[20:23] atmosphere nuclear tests, uh, conducted on,
[20:27] uh. Because there was a test ban treaty that
[20:29] was signed, uh, all the signatories
[20:32] said, no, we won't test nuclear, uh, weapons
[20:34] in the atmosphere. Uh, but they had to
[20:37] verify it. And so the verification process
[20:40] involved, uh, a number of satellites being
[20:42] launched that could detect gamma rays which
[20:44] would be emitted by a nuclear bomb being
[20:46] detonated in the atmosphere. Uh,
[20:49] now none were. But those
[20:52] satellites are what detected gamma ray
[20:54] bursts. These um, you know, fascinating
[20:57] pulses of radiation that come from, uh, from
[21:00] explosions deep in space. Yeah, of course,
[21:03] man made explosions, but natural ones. Yes.
[21:05] Andrew Dunkley: Because if they do start detecting nuclear,
[21:08] uh, weapons in space, then the
[21:11] parties involved, uh, they won't say, oh,
[21:14] sorry, sorry, we'll take them all down.
[21:16] They'll find ways of hiding them.
[21:18] Professor Fred Watson: Probably. Yes, that's probably right.
[21:21] Andrew Dunkley: Gosh, it's tough, isn't it?
[21:23] Professor Fred Watson: Uh, tough world we live in.
[21:24] Andrew Dunkley: Indeed. Uh, and beyond it in some
[21:27] respects. Uh, you can read that
[21:29] storey@universetoday.com. this
[21:32] is space Nuts with Andrew Dunkley and
[21:34] Professor Fred Watson Watson.
[21:40] Space Nuts.
[21:42] Uh, next storey, Fred Watson, uh, is
[21:45] looking at, uh, all the dust on Earth
[21:48] and where it might have come from. Now I was
[21:50] thinking cats because
[21:53] they do shed. Uh, but it's uh, a bit
[21:56] more involved than that. And what
[21:59] is really interesting about this storey is
[22:01] they think a heck of a lot of it came from
[22:04] one source.
[22:07] Professor Fred Watson: That's right. And it's a mysterious one as
[22:09] well. Um, so this is
[22:12] quite a nice storey, uh, from publishing, uh,
[22:15] Science Adventures. Um, it's
[22:18] about, uh, the
[22:20] micrometeorites that bombard the Earth.
[22:24] And it's a bit surprising, this
[22:27] stuff. Uh, you know, we think of meteorites
[22:29] as big chunks of rock that come through the
[22:32] atmosphere, they have a blaze of glory and
[22:34] then land on the Earth somewhere. And
[22:38] what we've got there is um, a
[22:41] free sample of extraterrestrial
[22:43] material. But there are also these
[22:46] micrometeorites which rain on the Earth's
[22:48] atmosphere and they're dust particles, as
[22:50] you've kind of hinted. Uh,
[22:53] um, and they're sort of always
[22:56] falling on Earth. Uh, and that,
[22:59] uh, is again, it's a free gift from space.
[23:03] Um, I think. So I was sort of
[23:06] vaguely involved with this stuff probably 50
[23:09] years ago, back in the 70s. I think they
[23:12] were then called Brownlee particles. Um.
[23:14] Oh, that sounds familiar. We're talking
[23:16] about. Yeah. Uh, but they're now,
[23:19] I think, called cosmic spherules. Uh, I
[23:21] should cheque whether Brownlee particles and
[23:24] cosmic spherules are the same thing, but
[23:26] basically what they are
[23:29] is bits of meteor that have
[23:33] melted as they come down through the
[23:35] Earth's atmosphere, but
[23:38] they actually survive into the inner
[23:40] atmosphere and they cool down and they form a
[23:43] little sphere because the um, basically the
[23:46] surface tension of molten material brings
[23:48] them into a sphere. Uh, and that
[23:51] uh, is the storey so far
[23:54] because that um, heating
[23:57] that you, that they experience as
[24:00] the sort of parent Body, the meteor. Meteor
[24:03] or meteorite, as it comes through the
[24:04] atmosphere, it, um,
[24:07] kind of destroys their chemical
[24:10] structure, you know, the minerals in it. It
[24:12] get metamorphosed, they get changed because
[24:15] they've been subject to very high
[24:16] temperatures. Um, but there is
[24:19] a technique, uh, that allows you
[24:22] to look at, uh, some
[24:25] of the characteristics of these
[24:27] objects that is not destroyed by
[24:30] heat. And it's the oxygen
[24:33] isotope signature, uh, which we've
[24:36] talked about before. We've talked about
[24:38] isotopes and how they, uh, you know, how we
[24:40] distinguish between heavy water and normal
[24:42] water and all of that sort, sort of thing.
[24:45] That's. So it's basically the. The number of,
[24:47] uh, neutrons in an atom. Um,
[24:51] so you've got these oxygen
[24:53] signatures, uh, that,
[24:56] um, essentially, uh, let you,
[24:59] ah, group these cosmic
[25:02] spherules, the Brownlee particles, if that's
[25:05] what they are. Um, and it turns out
[25:08] that so, so people do, you know, they do
[25:10] population census statistics on these objects
[25:13] to find out, uh, what
[25:16] relationships they bear with one another.
[25:19] About 10% of them of these
[25:22] ferals that have been identified and
[25:24] analysed collect in a group
[25:27] that has got the wonderful name of Group
[25:30] four, uh, which presumably means
[25:33] there's another three as well. Yeah. Um,
[25:36] and it's, uh, the. Again, what
[25:39] makes them stand out in this group is the
[25:42] oxygen isotope signature that I just
[25:45] mentioned before. It's depleted in, uh, an
[25:48] isotope called oxygen 16.
[25:51] But here's where the storey gets very
[25:54] interesting because, um,
[25:57] no known meteorites have
[26:00] that same oxygen isotope signature.
[26:03] And you'd expect, uh, if these
[26:06] things were common, that there would be
[26:09] meteorites, uh, that match them in their
[26:12] composition. Uh, and often with
[26:15] meteorites we can get an idea where they've
[26:17] come from. Uh, most of them come from the
[26:19] asteroid belt from collisions between
[26:21] asteroids. Uh, so, uh,
[26:24] um, that is a bit mysterious
[26:27] that we've got these subatomic, sorry, these
[26:31] small spherules of material that have come
[26:34] down through the atmosphere, uh, and got that
[26:36] globular shape. Um, it's
[26:40] mysterious that we don't know. We don't see
[26:42] any meteorites that match their
[26:45] composition.
[26:46] Andrew Dunkley: Weird.
[26:47] Professor Fred Watson: It is weird, yes. Uh, and so what
[26:50] they're suggesting is that, um,
[26:53] it's basically something that
[26:55] comes from an asteroid, uh,
[26:58] whose characteristics are unusual, uh,
[27:01] that we have not, uh, yet, um,
[27:03] identified it.
[27:06] Andrew Dunkley: Wow. Okay, so we're
[27:09] still looking.
[27:10] Professor Fred Watson: We're still looking. There's a sort of sub
[27:12] mystery as well because, um,
[27:17] a detailed analysis of this, you can break
[27:19] that Group 4 stuff down into other smaller
[27:22] groups. And, uh, some of them
[27:25] Basically show signs of having had two
[27:28] different, uh, minerals in
[27:31] them before they entered the Earth's
[27:33] atmosphere. And, um,
[27:36] one would be typical of,
[27:39] uh, well known types of asteroids. And the
[27:42] other, as I said, doesn't correspond to any
[27:44] kind of known, um, group of, uh,
[27:49] um, cosmic spherules or meteorites.
[27:52] Uh, and it's really quite
[27:54] remarkable that this, you know, we're being
[27:57] bombarded by dust particles that come from
[27:59] somewhere which we haven't identified.
[28:02] Professor Fred Watson: Yeah.
[28:02] Andrew Dunkley: Wow. Um, could that mean they're from
[28:05] beyond our system or it's just a part of the
[28:08] system that we.
[28:11] Professor Fred Watson: I think it's.
[28:11] Andrew Dunkley: I don't know.
[28:13] Professor Fred Watson: Yeah, I think it's the other way around. Um,
[28:15] because the m. The team who've done the
[28:18] research on this, a very, very thorough piece
[28:19] of research, they've basically,
[28:23] um, as you would, you've used, uh,
[28:25] simulations, computer simulations
[28:28] to, to essentially work out
[28:31] what conditions these things formed in when
[28:33] they, um, melted coming through the Earth's
[28:36] atmosphere. And it suggested that the best
[28:39] fit they get to what they see, the sort of
[28:42] textures that are in the material fit
[28:45] with relatively low
[28:47] velocities, uh, 14 to 17 kilometres
[28:50] per second. Uh, which is
[28:53] pretty speedy when you think of it on Earth.
[28:55] But, um, uh, in space, that's a
[28:58] fairly modest, uh, space speed for a
[29:00] meteorite that typically will be more like 30
[29:03] kilometres per second. And so that
[29:05] low value, uh, suggests
[29:08] that possibly those
[29:11] particles originated in near
[29:13] Earth asteroids, um, ones
[29:16] that are, um, following a similar path
[29:19] through space to the Earth. And that
[29:22] might mean that we've got some sort of,
[29:26] um, in the Earth's environment, some
[29:28] sort of unusual asteroid
[29:31] that is not, not matched by all the ones that
[29:34] we know already.
[29:35] Professor Fred Watson: Wow.
[29:35] Andrew Dunkley: That'd be something, uh, that's probably
[29:37] gonna be hard to track down though.
[29:39] Professor Fred Watson: Yes, yes, that's probably right. And
[29:41] especially since it might not exist anymore,
[29:43] it may have collided and formed little bits
[29:45] that have basically rained down on the Earth.
[29:47] Andrew Dunkley: Yeah. Now, it wasn't Thea. Rusty just.
[29:51] Professor Fred Watson: No, it wasn't Thea. That's right. Yeah.
[29:52] Thanks, Rusty. It's not Thea.
[29:55] Andrew Dunkley: Um, for the record, Brownlee particles and
[29:57] cosmic spherules are closely related, but
[29:59] they are not exactly the same thing.
[30:01] Professor Fred Watson: Okay.
[30:02] Andrew Dunkley: They represent two different ages or types
[30:05] of micrometeorites.
[30:07] Professor Fred Watson: There you go. Thank you for checking that.
[30:10] Yes, that's all right.
[30:11] Andrew Dunkley: Um, yeah, they're very close, but they're
[30:13] not, not the same.
[30:14] Professor Fred Watson: So I was on the right track.
[30:15] Andrew Dunkley: You were, yes.
[30:17] And you can read all about that at, uh,
[30:20] the AstroDailyPod Galaxy website. Um, and
[30:23] the article Was published where,
[30:25] Fred Watson, I've lost the science advances.
[30:29] That's right, yes. Want to read the whole
[30:31] thing before bed so you sleep well?
[30:34] Professor Fred Watson: Yep.
[30:35] Professor Fred Watson: Yeah.
[30:35] Andrew Dunkley: This is Space Nuts with Andrew Dunkley and
[30:37] Professor Fred Watson Watson.
[30:40] Professor Fred Watson: We choose to go to the moon in this decade
[30:43] and do the other things, not because they are
[30:46] easy, but because they are hard, these nuts.
[30:50] Andrew Dunkley: Our, ah, final storey today takes us
[30:53] to the edge of our galaxy. Well, it takes us
[30:56] from the centre of our galaxy right out to
[30:58] the edge of our galaxy because we're talking
[30:59] about the whole thing lock, stock and barrel.
[31:02] And it appears, Fred Watson, with some very
[31:04] clever scientific brains in action,
[31:07] that, uh, our galaxy stretches out further
[31:10] than we thought.
[31:13] Professor Fred Watson: Uh, it does. It looks as though the spiral
[31:15] arms are longer than we thought they were.
[31:18] And I think this is a very nice piece of
[31:21] work, uh, as, uh, I hinted before,
[31:24] uh, partly because it uses a technique that I
[31:27] think is really extraordinary. It's a very
[31:29] powerful technique, uh, using what we call
[31:31] light echoes. Um,
[31:35] so the storey, basically, to set this in
[31:37] context, it's very hard for us to
[31:40] produce a map of what our own galaxy looks
[31:42] like. And that's because we're embedded in
[31:45] one of the spiral arms. Uh, the
[31:48] stars that we see when we look at the Milky
[31:50] Way. They're stars that, uh, fellow
[31:53] travellers in the spiral arms with our, uh,
[31:55] sun and solar system. But they only go out to
[31:57] 1000 light years or so because the spiral
[32:00] arms are so dusty that you can't really
[32:02] penetrate much beyond that. Um,
[32:05] and if you were relying only on visible
[32:07] light, uh, it would be
[32:10] like trying to draw a map
[32:13] of the whole of Dubbo from
[32:16] standing outside Dubbo jail there on, um,
[32:20] uh, forgotten. Is that Macquarie Street?
[32:22] Andrew Dunkley: Macquarie street, yeah.
[32:23] Professor Fred Watson: Yes, yes.
[32:24] Andrew Dunkley: Oh, for the record, they're putting a, um,
[32:27] they've taken down the public building in
[32:28] front of the old Dubbo jail.
[32:30] Professor Fred Watson: Oh, there you go.
[32:30] Andrew Dunkley: Now they're turning it into a public
[32:33] common. Common.
[32:35] Professor Fred Watson: I, uh, like that idea.
[32:36] Andrew Dunkley: That's going to look very nice when it's
[32:38] done.
[32:39] Professor Fred Watson: So that would improve your view of the city
[32:41] of Dubbo, but it still might not let you make
[32:43] a map of Dubbo from just there. Uh,
[32:46] and that's how we are in our galaxy. If
[32:48] you're relying on visible light observations,
[32:52] uh, all you're seeing when you look
[32:55] is the neighbourhood of, uh, our
[32:57] spiral arm, a local spiral arm. You don't get
[32:59] any hint or inclination of the structure of
[33:02] the galaxy, uh, beyond that. And in
[33:05] particular, you know, if we see
[33:08] a thousand light years or so, there's another
[33:11] Hundred thousand that we're not seeing
[33:12] because that's about the diameter of, ah, our
[33:14] galaxy. So, um, ah, the
[33:17] situation improves when you use infrared, uh,
[33:20] radiation. You can sort of penetrate, uh,
[33:23] through the dust and see actually the centre,
[33:25] towards the centre of our galaxy. That's how
[33:27] we know about the black hole in the centre of
[33:30] our galaxy, because we could see stars
[33:31] orbiting around it. Um, but
[33:34] it improves even more on a broader scale if
[33:37] you can use radio telescopes, because you can
[33:39] plot, um, where the clouds of
[33:42] hydrogen gas called hydrogen, uh, which
[33:45] radiates in, uh, radio waves, uh, with a
[33:48] wavelength of 21 centimetres, uh, that you
[33:51] can plot out. But if you're going to try and
[33:53] draw a map, you do need to do some modelling
[33:55] with that. You've got to assume things about
[33:57] the rotation of the galaxy so it doesn't just
[33:59] give you a direct map, map. And that could
[34:02] be wrong. We could have that little bit of it
[34:04] wrong, uh, you know, uh, the stuff that comes
[34:07] from the radio observations. So
[34:10] what's happened now is it's a
[34:13] team, uh, I think they're based in Italy,
[34:16] uh, and what they've done
[34:19] is used, um,
[34:23] a direct method of kind of
[34:26] setting up a standard ruler. Uh, because if
[34:29] you've got a standard ruler and you can see
[34:30] it in deep space, then you know how far away
[34:32] it is because you can measure how long it
[34:34] appears to be. And if you know how long it
[34:37] is, which is what a standard ruler is, then
[34:39] you know how far away it is. And that's
[34:42] what they're doing. They have. And it goes
[34:45] back to something we mentioned earlier in the
[34:47] show, gamma ray bursts. These bursts of gamma
[34:49] radiation, those
[34:52] bursts, uh, don't just directly come to
[34:55] us, they also bounce off or are
[34:57] reflected by clouds of dust in our
[35:00] spiral arms. And, uh, so
[35:04] by timing how long,
[35:07] uh, it takes for these echoes, as
[35:10] they're called, light echoes, even though
[35:12] it's gamma radiation, uh, to what
[35:15] the delay is between a light
[35:18] echo and the, uh, source itself,
[35:21] which is the gamma ray burst, I should say
[35:22] they probably come from collapsing
[35:25] massive stars or merger of neutron
[35:27] stars, uh, very energetic events
[35:31] because they're bright in gamma radiation.
[35:33] But if you look at a light echo from a gamma
[35:36] ray burst, it gives you a scale to this,
[35:39] you know, um, how far.
[35:42] Basically, uh, it gives you a standard ruler,
[35:44] um, because you can time it accurately, you
[35:47] know that 300,000 kilometres per second is
[35:50] the speed of gamma rays through space. And,
[35:52] you know, if you know how far away it's gone
[35:54] in that time, then that gives you a distance
[35:56] measure. So you've got a standard ruler. Uh,
[35:59] it's a very, very nice way of doing this.
[36:01] And, um, using that, uh, these,
[36:04] uh, scientists, um, as I
[36:07] said, uh, at least the lead author is, uh,
[36:10] certainly in Italy at ENAF in Milano,
[36:13] uh, uh, they've done this work
[36:16] looking at these gamma ray bursts with their
[36:18] light echoes, and that allows them to
[36:20] calculate basically the size of our, uh,
[36:23] spiral arms without relying on any kind of
[36:26] modelling. And so
[36:28] they think that the new
[36:31] observations indicate that, uh, our spiral
[36:34] arms are something like 10%
[36:37] longer than we thought they were. Wow,
[36:39] that's, uh.
[36:39] Professor Fred Watson: A lot.
[36:40] Professor Fred Watson: Yes. That's significant, isn't it? It's
[36:42] really, um. You know, this is. As I said,
[36:45] this is very nice, uh, nice astronomy.
[36:48] Andrew Dunkley: It is indeed. Yeah. Um, of
[36:50] course, as you say, we can't really look at
[36:53] our galaxy. We don't know exactly what it
[36:55] looks like. Um, there's a lot of science that
[36:57] they've put together to try and create
[37:00] the image of it. And even in this particular
[37:03] storey, uh, which is in the Universe Today
[37:05] dot com, they've got an artist's impression
[37:07] of what this new, uh, look is like.
[37:10] Professor Fred Watson: Yes. That's all you can do.
[37:11] Andrew Dunkley: Reminds me of an upside down snail.
[37:15] Professor Fred Watson: It does, yes, that's right. I see what you
[37:18] mean. Yes, yes.
[37:22] Andrew Dunkley: Or a squid. Could be a squid.
[37:24] Professor Fred Watson: Could be a squid, yeah.
[37:26] Andrew Dunkley: Uh, but in real terms we just have
[37:29] to. It's an edge. Very, very educated
[37:32] guess, I suppose.
[37:33] Professor Fred Watson: Um, yes, it is. It's a measurement.
[37:37] So you're right,
[37:40] it's an artist's impression. That's really
[37:41] the only way we can depict the Milky Way.
[37:43] Some of the depictions are very, very good
[37:45] and they rely on the very best radio and
[37:47] infrared observations that have been made.
[37:50] But this is going to modify it a little bit
[37:52] by our new knowledge of the spiral arms. And
[37:55] I should say, um, this, the, um.
[37:58] It's the Chandra satellite, uh, which is a,
[38:01] ah, an X ray observatory, um,
[38:04] by. Operated by NASA, uh,
[38:07] that has been used to make the measurements.
[38:10] And I do like the headline on a little, uh,
[38:13] NASA video that there is Here, which is
[38:15] NASA's Chandra examines Milky Way at
[38:17] Arm's Length.
[38:18] Andrew Dunkley: Yeah, nice. Um, very
[38:21] well done.
[38:22] Professor Fred Watson: Clever, clever. Yeah, they are.
[38:25] There's some good people there.
[38:26] Andrew Dunkley: Uh, so the articles in Universe Today, but
[38:28] you can read it in a deeper form
[38:31] through the NASA website or the, uh,
[38:35] Astronomy and Astrophysics Journal, I think,
[38:37] has published, uh, the full paper, which is.
[38:40] Professor Fred Watson: Yeah, that's the European journal.
[38:43] Andrew Dunkley: Lots of numbers in it. Yeah, lots and
[38:45] lots of numbers. Numbers that are too big
[38:48] for my brain.
[38:51] All right, uh, that's where we end the show.
[38:54] Fred Watson, thank you very much.
[38:55] Professor Fred Watson: Much.
[38:56] Professor Fred Watson: Oh, a pleasure. Uh, as you said at the
[38:58] beginning, some nice storeys there.
[38:59] Andrew Dunkley: Yeah. I'm very glad to be able to
[39:01] Professor Fred Watson: share them with you.
[39:02] Andrew Dunkley: Indeed. Uh, we'll catch you real soon. Thank
[39:04] you, Fred Watson.
[39:05] Professor Fred Watson: No worries. Thanks, Andrew.
[39:06] Andrew Dunkley: Professor Fred Watson Watson, astronomer at
[39:08] large, and, uh, as I say, between episodes,
[39:10] Visit our website, spacenutspodcast.com or
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[39:28] a supporter. You can do that too. And don't
[39:30] forget to leave reviews of Space Nuts, your
[39:33] favourite podcasting platform. And thanks to
[39:35] Huw in the studio because he didn't turn up
[39:37] today. And from me, Andrew Duckling. Whoops.
[39:40] Uh, thanks for your company. We'll catch you
[39:42] on the next episode of Space Nuts. Bye. Bye.
[39:45] You've been listening to the Space Nuts
[39:48] podcast, available at
[39:51] Apple Podcasts, Spotify,
[39:53] iHeartRadio or your favourite podcast player.
[39:56] You can also stream on demand@bytes.um.com.
[39:59] Professor Fred Watson: this has been another quality podcast
[40:01] production from bytes.um.com.

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