Nuclear Satellite Inspections, New Horizons Awakens, and a Cosmic Catalog of Galaxy Clusters

0:00 Anna: Hello and welcome to Astronomy

0:02 Daily. I'm Anna.

0:04 Avery: And I'm avery. It's Thursday, July

0:06 9, 2026, and we've got a proper

0:09 mixed bag for you today.

0:11 Anna: We've got nuclear physics hibernating

0:13 spacecraft, a map of thousands of

0:16 galaxy clusters, a moon delivery deal,

0:19 a rocket breaking its own record, and

0:22 we'll finish up looking at the evening sky.

0:24 Avery: Six stories, 16 minutes. Let's get into

0:27 it, Avery.

0:28 Anna: This first one sounds like the plot of a

0:30 thriller novel, but it's a real peer reviewed

0:33 paper that came out this week.

0:35 Avery: It really does. So here's the setup.

0:38 The 1967 Outer Space Treaty

0:41 bans nuclear weapons in orbit.

0:43 118 countries have signed it, including the

0:46 US and Russia. Problem is, there's never been

0:49 an actual way to check whether a satellite is

0:52 quietly breaking that rule.

0:54 Anna: Which matters a lot more than it might have a

0:56 few years ago, because back in February

0:59 2022, Russia launched a

1:01 satellite called Kosmos

1:03 2553 into a very

1:06 strange, very high radiation orbit.

1:09 Weeks later, they invaded Ukraine.

1:12 Avery: Russia says it's just a sensing and

1:14 surveillance satellite. U.S. officials have

1:17 suspected for a while that it might actually

1:19 be testing components for a nuclear anti

1:21 satellite weapon.

1:23 Anna: So how do you check without just taking

1:25 someone's word for it?

1:27 Avery: That's exactly the problem MIT physicist

1:30 Arag denagulian set out to solve, publishing

1:32 his solution in nature on July 8th.

1:35 His idea is a shoebox sized inspector

1:38 satellite, a nine unit cubesat that

1:41 flies up close to a suspect satellite.

1:43 Anna: And it's not looking for the bomb directly,

1:46 is it? It's looking for a signature,

1:49 right?

1:49 Avery: Neutrons. Earth's Van Allen radiation

1:52 belts are full of high energy protons.

1:55 And if there's a nuclear device up there,

1:57 those protons interacting with it produce a

2:00 very specific neutron signal. Dana

2:02 Gulian's modeling shows a single CubeSat

2:05 could confirm a nuclear warhead from about

2:07 4km away in roughly a week of

2:10 watching a constellation of 10 of them would

2:13 do it much faster.

2:14 Anna: Why does this even matter? Beyond the treaty

2:16 paperwork, what actually happens if someone

2:19 detonates a nuclear weapon in orbit?

2:22 Avery: This has actually been tried, believe it or

2:24 not. Back in 1962, the US ran

2:27 a test called Starfish Prime, a, ah,

2:29 1.4 megaton warhead detonated

2:32 in orbit. It pumped so many high energy

2:35 electrons into the Van Allen radiation belts

2:38 that it knocked out several satellites of

2:40 that era just, just from the radiation

2:42 environment it created.

2:44 Anna: So a modern version of that wouldn't just

2:46 take out one target, it could wipe out huge

2:49 swaths of orbit Reconnaissance

2:51 satellites, communications, gps,

2:54 starlink, all of it

2:56 indiscriminately.

2:57 Avery: Yes, which is exactly why Denaghulian is

3:00 up front that this isn't a uh, finished,

3:02 ready to launch system yet. His quote was

3:06 quote, this isn't a completely proven system.

3:09 The purpose of the paper is to show the

3:11 scientific community that it's scientifically

3:13 possible to do this.

3:14 Anna: I really like his line about why physics

3:17 based verification matters, especially

3:20 between countries that don't trust each other

3:22 very much.

3:23 Avery: You can fake intelligence, but you can't fake

3:26 physics. And that's really the heart of it. A

3:28 shoebox satellite that just measures

3:30 neutrons, doesn't care about geopolitics,

3:33 it just tells you what's actually there.

3:35 Anna: A genuinely elegant idea for a

3:38 genuinely unsettling problem.

3:41 Avery: From the very human problem of nuclear

3:43 weapons to a much older, much

3:46 quieter kind of drama.

3:47 NASA's New Horizons spacecraft just woke up.

3:50 Anna: It's been asleep for a while, hasn't it?

3:53 Avery: Its longest hyper mission yet.

3:55 321 days starting back on

3:58 August 7th last year. NASA confirmed on

4:01 July 7th that it's safely woken up in good

4:03 health.

4:04 Anna: And just to put the distance in perspective,

4:07 where actually is New Horizons right now?

4:10 Avery: 5.9 billion miles from Earth.

4:13 9.5 billion kilometers. That's so

4:16 far out that a radio signal traveling at the

4:19 literal speed of light takes 8 hours and

4:22 52 minutes just to get here one way.

4:25 Anna: So mission control says good morning and

4:27 doesn't hear back until almost lunchtime.

4:30 Avery: Pretty much. Mission operations manager Alice

4:33 Bowman said every single weekly status

4:36 beacon through the entire hibernation came

4:38 back green. Everything nominal the whole

4:41 time.

4:42 Anna: What's actually asleep during hibernation

4:44 though? Because it wasn't doing nothing out

4:46 there,

4:47 Avery: Most systems powered down to save energy. But

4:50 the science instruments kept working the

4:52 entire time. The solar wind around

4:54 Pluto or swap. The Pluto

4:57 Energetic Particle Spectrometer and

5:00 and the Venetia Burney student dust counter.

5:03 All quietly gathering ADA the whole way

5:05 through.

5:06 Anna: So now it's awake. What happens?

5:08 Avery: First, health and safety data comes down

5:11 first. Then the team starts retrieving nearly

5:14 a year's worth of stored science data. In

5:17 about three weeks, the onboard Alice

5:19 ultraviolet spectrograph will start studying

5:22 hydrogen gas out in the heliosphere while

5:24 swap Pepsi and the dust counter keep

5:27 measuring as engineers run instrument

5:29 checkouts.

5:30 Anna: This spacecraft's had quite a Life already.

5:33 Avery: Launched January 26,

5:36 2006. Fastest human made object

5:39 ever launched at the time. Blue pass, Pluto

5:42 in 2015 gave us our first close look at

5:45 the Kuiper Belt object arrokoth in

5:47 2019. And now it's pressing on toward

5:50 the true edge of the solar system's

5:52 heliosphere.

5:53 Anna: And it's running on updated Autonomy software

5:56 now too, to cope with the growing distance.

5:59 Avery: Exactly accounting for the slow decline in

6:01 power from its plutonium generator and the

6:04 ever lengthening delay in talking to Earth,

6:07 NASA HM expects it to keep returning good

6:09 data well into the2030s.

6:12 Anna: Nine hours for a single good morning

6:14 message. That's the kind of patience this

6:17 mission runs on.

6:18 Alright, moving on. This next one's been

6:20 making the rounds this week and it's a

6:22 genuinely enormous data set. A new

6:25 catalog of more than 7,000 galaxy

6:28 clusters built from five years of

6:30 Avery: data from the South Pole telescope,

6:32 specifically its SPT3G

6:35 camera out at the Amundsen uh, Scott South

6:37 Pole Station in Antarctica. An Argonne

6:40 National Laboratory led team put it together.

6:43 Anna: How much is the sky are we actually talking

6:45 about here?

6:46 Avery: About 4%, 1600

6:49 square degrees out. Out of that patch they

6:51 identified 8892

6:54 candidate clusters and confirmed

6:56 7190 of them.

6:59 Around 1800 of those date back more than

7:02 7.8 billion years.

7:05 Anna: How do you even spot a galaxy cluster? From a

7:07 telescope in Antarctica pointed at the sky?

7:10 Rather than say an optical telescope looking

7:12 at galaxies directly, they used something

7:15 called

7:15 Avery: the Sunyaev Zel Dutch effect. Light from

7:18 the cosmic microwave background. The

7:21 afterglow of the Big Bang passes through a

7:23 galaxy cluster on its way to us. And high

7:26 energy particles in the cluster subtly

7:28 distort that light. It leaves behind a faint

7:31 shadow like signature that the telescope can

7:34 pick up.

7:34 Anna: And then they double checked those detections

7:37 with something else.

7:38 Avery: Optical confirmation came from the Dark

7:40 Energy Survey. And here's the bit that

7:43 surprised even the researchers. The data

7:45 showed a marked increase in dust related

7:48 emission from these cluster environments.

7:50 Further back in time, that's a new window

7:53 into how star formation activity evolved in

7:56 and around these massive structures.

7:58 Anna: Why do galaxy clusters matter so much to

8:01 cosmologists?

8:02 Avery: Specifically, they're the largest

8:04 gravitationally bound structures in the

8:06 universe. Hundreds to thousands of

8:09 galaxies held together with hot gas and

8:11 huge amounts of dark matter. Because of

8:14 that scale, they're one of the best tools we

8:17 have for testing ideas about dark matter and

8:19 dark energy.

8:20 Anna: Sebastian Bouquet from the SPT

8:23 collaboration put it nicely, didn't he?

8:25 Avery: He did. Quote with the

8:27 SPT3G cluster sample we will

8:30 probe the evolution of cosmic structure

8:32 formation over the past 10 billion years.

8:36 And this is really just a start. Future work

8:38 will refine the cluster mass measurements and

8:41 upcoming surveys from the Vera Rubin

8:43 Observatory and Europe's Euclid Miss should

8:46 confirm M even more distant clusters in the

8:48 same patch of Sky.

8:49 Anna: Nearly 9,000 candidate structures,

8:52 each one holding thousands of galaxies.

8:55 And that's only 4% of the sky.

8:58 Avery: From cosmology back down to Earth. Well,

9:01 down to the moon, really. And the business of

9:03 getting there.

9:04 Anna: This is the Ispace and Starship story.

9:07 Avery: That's the one. Tokyo based lunar transport

9:10 company ispace announced on July 8 that

9:13 it's bought 500 kilograms, around

9:16 1100 pounds of cargo space

9:18 aboard a future starship mission targeting a

9:21 moon landing no earlier than 2030.

9:24 Anna: What did that actually cost them?

9:25 Avery: Um, around US$50

9:28 million, which works out to roughly

9:30 $100,000 per kilogram to the lunar

9:33 surface.

9:34 Anna: That's ispace's new business, isn't it?

9:37 Not just landing their own stuff, but

9:39 carrying other people's payloads too.

9:41 Avery: Exactly right. They're calling it their Lunar

9:44 Access Integrator Service. Think of it as a

9:47 shared ride bus to the moon. They'll

9:49 aggregate smaller payloads from governments,

9:51 research institutions and commercial

9:53 customers, which is a different business, to

9:56 their existing dedicated lander service,

9:58 which they describe as a more of a taxi.

10:01 Anna: And once Starship actually lands, how

10:04 does the cargo get to where it needs to go?

10:06 Avery: That's where ispace's own mobile cargo system

10:09 comes in. A rover they're developing that can

10:12 carry payloads a few kilometers from the

10:14 landing site to their final destination.

10:17 Anna: CEO Takeshi Hakamada had a good line about

10:20 why this matters.

10:20 Avery: For the bigger picture, Quote, high

10:23 capacity, relatively low cost lunar

10:25 transport, such as that provided by Starship,

10:28 is essential for realizing a sustainable

10:30 lunar economy that Ispace aims to create.

10:33 Anna: Now, I have to ask, ispace's track record

10:36 on actual landings hasn't been perfect.

10:39 Avery: No, it hasn't. They flown two lunar lander

10:42 missions on SpaceX Falcon 9 rockets in

10:45 2023 and 2025, and

10:48 both reached lunar orbit successfully, but

10:51 crashed during landing. They're now

10:53 developing a, uh, new lander design called

10:55 ultra, with three missions planned between

10:57 2028 and 2030, including

11:00 one under NASA's Commercial Lunar Payload

11:02 Service program.

11:04 Anna: So rather than betting everything on getting

11:06 their own landings right, they're also

11:08 building a second business on somebody else's

11:11 rocket.

11:12 Avery: Precisely. And SpaceX seems keen on it too.

11:14 Their VP of Commercial Sales, Stephanie

11:17 Bednarig, said this gives, quote, a VALU

11:20 pathway for smaller payloads to secure a ride

11:22 to the moon today. Worth milling. This isn't

11:25 exclusive either. NASA's using Starship for

11:28 the crewed Artemis lander and the US company

11:31 AstroLabe has separately booked starship

11:33 cargo space as well.

11:34 Anna: Two failed landings hasn't slowed them down

11:37 one bit. If anything, they're doubling down

11:40 on the moon, just letting someone else do the

11:42 heavy lifting this time. Right, quick one

11:45 now, but a satisfying one if you like your

11:47 rockets to keep proving a point.

11:50 Avery: SpaceX launched the Falcon 9 out of Cape

11:52 Canaveral early this morning, July 9,

11:55 5:25am M Eastern Time, carrying

11:57 29 Starlink satellites.

12:00 Anna: And the headline isn't really the satellites,

12:03 Avery: no, it's the booster tail number.

12:05 B1067 flew for the

12:07 36th time today, breaking its own company

12:10 record, which was 35 flights.

12:13 Anna: For comparison, where does that sit against

12:15 the all time record for any reusable orbital

12:18 vehicle?

12:19 Avery: Still behind NASA's space shuttle Discovery,

12:21 which flew 39 times across its career.

12:24 But B1067 is closing the gap,

12:27 and it's doing it on a much faster turnaround

12:30 cadence than Discovery ever could.

12:32 Anna: What happened to the booster after

12:34 separation?

12:35 Avery: About eight and a half minutes after liftoff,

12:37 it landed on the drone ship, a shortfall of

12:39 gravitas out in the Atlantic. The upper

12:42 stage carried on and deployed those 29

12:45 Starlink satellites to low Earth orbit around

12:47 63 and a half minutes after launch.

12:50 Anna: This is launch number 80 for Falcon 9 this

12:52 year already, isn't it?

12:54 Avery: It is, and SpaceX president Gwynne Shotwell

12:57 has said they're targeting somewhere around

12:59 140 to 145

13:01 Falcon 9 launches this year. SpaceX now

13:04 has more than 10,700 active

13:07 Starlink satellites in orbit. About 80%

13:10 of this year's flights have gone toward

13:12 building that constellation out.

13:14 Anna: 36 trips to space and back for the exact

13:17 same piece of hardware. Reusable rockets have

13:20 gone from a wild idea a decade ago to a

13:23 company quietly breaking its own record on an

13:25 ordinary Thursday morning.

13:27 Avery: And to close things out, something that

13:29 doesn't need a spacecraft, a, uh, peer

13:31 reviewed paper or a rocket. Just clear

13:34 skies and about 10 minutes after sunset.

13:36 Anna: This is tonight's sky, isn't it, July 9th?

13:39 Avery: That's right. Venus is putting on a lovely

13:42 little show, sitting close to Regulus, the

13:44 brightest star in the constellation Leo, low

13:47 in the evening sky after sunset.

13:49 Anna: And Venus is easy to find regardless because

13:51 it's so bright.

13:52 Avery: It's the brightest point of light in the sky

13:54 after the Moon. So this pairing is genuinely

13:57 a, uh, naked eye, no equipment needed kind of

14:00 moment. Look west after sunset and you can't

14:02 really miss it.

14:03 Anna: So of course, Venus and Regulus aren't

14:06 actually anywhere near each other in real

14:08 terms, not remotely.

14:10 Avery: Regulus is a proper star about 79

14:13 light years away. Venus is right here in our

14:16 own solar system. It's purely a trick of

14:18 perspective. From where we're standing, they

14:21 line up and look like neighbors.

14:23 Anna: And there's more to come this month, too.

14:25 Avery: There is. Venus goes on to meet a slender

14:28 crescent moon on July 17. So if you

14:30 enjoy this one, pencil that date in as well.

14:33 Anna: And for our listeners south of the

14:35 Avery: equator, Venus and Leo are still catchable

14:38 low in the western sky after sunset. For

14:40 Southern Hemisphere viewers, too. Well worth

14:42 a look if you want an easy win with the

14:44 family. No telescope required.

14:46 Anna: Sometimes the best story of the day really is

14:49 just look up right there. Tonight.

14:52 Avery: That's today's edition of Astronomy Daily.

14:55 Nuclear physics A Ah, spacecraft waking up

14:57 nine hours from home, thousands of galaxy

15:00 clusters, a moon delivery deal, a record

15:03 breaking rocket, and a couple of bright dots

15:05 in tonight's sky.

15:06 Anna: If you enjoyed today's episode, please hit

15:09 subscribe wherever you're listening and leave

15:11 us a review. It genuinely helps new listeners

15:13 find the show.

15:14 Avery: Show and here's today's did you know for you,

15:17 New Horizons radio signal takes almost

15:19 nine hours to reach Earth, which means by the

15:22 time mission control hears all systems green,

15:25 the spacecraft has already been fine for the

15:27 better part of a working day.

15:29 Anna: I'm Anna.

15:30 Avery: And I'm Avery. We'll see you next time on

15:32 Astronomy Daily.

15:40 Anna: Love.