Artemis, Pulsars, Big Crunch & City Killers

0:00 Speaker 1: Welcome to Astronomy Daily.

0:02 Speaker 2: I'm Anna and I'm Avery. It is Thursday, the nineteenth

0:06 Speaker 2: of February twenty twenty six, and we are recording this

0:10 Speaker 2: episode while NASA is literally fueling a rocket at this

0:13 Speaker 2: very moment, and we cannot wait to tell you about it.

0:17 Speaker 1: That's right. This is one of those days where space

0:20 Speaker 1: news isn't just something that happened somewhere out there in

0:23 Speaker 1: the universe. It is happening right now on a launchpad

0:27 Speaker 1: in Florida. But that's not all today. We're also asking

0:31 Speaker 1: what lurks in the darkness between us and our nearest

0:34 Speaker 1: cosmic neighbors. Could there be a cosmic clock ticking next

0:38 Speaker 1: to the most extreme object in our galaxy? And brace yourselves?

0:43 Speaker 1: Is the universe actually going to end?

0:46 Speaker 2: Plus, we have a story that will make you want

0:48 Speaker 2: to check the sky tonight, a warning from NASA that

0:51 Speaker 2: is genuinely a little unsettling, and we're going to space

0:55 Speaker 2: with a music video. All of that is coming up

0:57 Speaker 2: on Astronomy Daily.

0:59 Speaker 1: Let's start with the big one, and I mean big

1:02 Speaker 1: in every sense of the word. As we speak, NASA's

1:05 Speaker 1: Space Launch System, the most powerful rocket ever built, is

1:10 Speaker 1: being loaded with more than seven hundred thousand gallons of

1:13 Speaker 1: cryogenic propellant at Launch Complex thirty nine B at Kennedy's

1:18 Speaker 1: Space Center in Florida.

1:20 Speaker 2: This is the second wet dress rehearsal for Artemis two,

1:23 Speaker 2: the mission that will carry four astronauts on a loop

1:25 Speaker 2: around the Moon, the first time humans have ventured to

1:28 Speaker 2: lunar distance since Apollo seventeen back in nineteen seventy two.

1:33 Speaker 2: The crew are Commander Reidwiseman, pilot Victor Glover, mission specialist

1:38 Speaker 2: Christina Cokes from NASA, and Jeremy Hansen from the Canadian

1:42 Speaker 2: Space Agency.

1:43 Speaker 1: Now. The reason they're doing this rehearsal and the reason

1:46 Speaker 1: there have been so many eyes on it today, is

1:49 Speaker 1: that the first attempt, back on the second and third

1:52 Speaker 1: of February, did not go as planned. Engineers detected a

1:56 Speaker 1: liquid hydrogen leak during fueling, which forced them to halt

1:59 Speaker 1: the test before they could complete the full countdown sequence.

2:03 Speaker 2: In the week, sense technicians have replaced seals around two

2:06 Speaker 2: fueling lines, swapped out a filter in the ground support equipment,

2:10 Speaker 2: and added an extra hour of buffer time into the

2:13 Speaker 2: countdown to allow more room for troubleshooting. It's the kind

2:16 Speaker 2: of painstaking, unglamorous engineering work that rarely makes headlines, but

2:21 Speaker 2: it's exactly what keeps astronauts alive.

2:24 Speaker 1: Today's rehearsal targets a simulated launch window opening at eight

2:28 Speaker 1: thirty this evening Eastern Time. The test is expected to

2:31 Speaker 1: run until around twelve thirty Friday morning, and the stakes

2:35 Speaker 1: are high. NASA has said it won't set a formal

2:38 Speaker 1: launch date until after a successful wet dress rehearsal campaign.

2:43 Speaker 1: March sixth remains the earliest possible crude launch date.

2:47 Speaker 2: NASA Administrator Jared Isaacman put it well when he said,

2:50 Speaker 2: we anticipated encountering challenges. That is precisely why we conduct

2:54 Speaker 2: a wet dress rehearsal. These tests are designed to surface

2:58 Speaker 2: issues before flight. This safety of the crew comes first.

3:01 Speaker 2: So tonight we watch and we wait.

3:04 Speaker 1: We will be keeping a close eye on this one,

3:07 Speaker 1: and we'll bring you the results intomorrow's episode. Fingers crossed

3:10 Speaker 1: for a clean test, no leaks, and a March launch

3:14 Speaker 1: that puts humans back in the vicinity of the Moon

3:16 Speaker 1: for the first time in over fifty years.

3:19 Speaker 2: All right from a rocket at Kennedy Space Center to

3:22 Speaker 2: the absolute heart of our galaxy, and this story is

3:26 Speaker 2: one of those discoveries that, if it's confirmed, could fundamentally

3:30 Speaker 2: change how we understand the universe.

3:33 Speaker 1: Researchers from Columbia University, working with the Breakthrough Listen initiative,

3:37 Speaker 1: which is best known for searching for signs of intelligent

3:40 Speaker 1: life beyond Earth, have announced the detection of a candidate

3:43 Speaker 1: millisecond pulsar very close to Sagittarius, a star that's the

3:48 Speaker 1: super massive black hole sitting at the center of the

3:51 Speaker 1: Milky Way, roughly four million times the mass of our

3:55 Speaker 1: own Sun.

3:56 Speaker 2: So let's unpack what a pulsar is, because it's one

4:00 Speaker 2: of the most extraordinary objects in the universe. When a

4:04 Speaker 2: massive star reaches the end of its life and explodes

4:07 Speaker 2: as a supernova, what's left behind is an incredibly dense

4:11 Speaker 2: core called a neutron star. Some of those neutron stars

4:14 Speaker 2: spin rapidly and emit beams of radio waves like a

4:18 Speaker 2: cosmic lighthouse sweeping through space. When those beams sweep past Earth,

4:23 Speaker 2: we detect them as regular pulses, hence pulsar.

4:27 Speaker 1: And what makes millisecond pulsar special is their extraordinary precision.

4:32 Speaker 1: They spin hundreds of times per second with almost perfect

4:35 Speaker 1: regularitydientists have called them the most accurate clocks in the universe,

4:40 Speaker 1: more stable than atomic clocks here on Earth. This candidate,

4:43 Speaker 1: nicknamed BLPSR, completes one full rotation every eight point one

4:48 Speaker 1: nine milliseconds.

4:50 Speaker 2: Now here's why finding one near Sagittarius a star is

4:53 Speaker 2: such a big deal. A pulsar next to a four

4:57 Speaker 2: million solar mass black hole would be operating in one

5:00 Speaker 2: of the most extreme gravitational environments imaginable, and Einstein's general

5:05 Speaker 2: theory of relativity makes very specific predictions about what happens

5:09 Speaker 2: to space and time in such extreme environments, predictions that

5:14 Speaker 2: have never been tested at this level of precision.

5:17 Speaker 1: And if a pulsar is orbiting close to Sagittarius astar,

5:21 Speaker 1: the black hole's gravity would warp space time so severely

5:24 Speaker 1: that those precise pulsar pulses would arrive at our telescopes

5:28 Speaker 1: with tiny but measurable distortions. As researcher Slovko Bogdanov from

5:32 Speaker 1: Columbia put it, any external influence on a pulsar would

5:36 Speaker 1: introduce anomalies in the steady arrival of pulses, which can

5:40 Speaker 1: be measured and modeled.

5:41 Speaker 2: In other words, a confirmed pulsar next to a super

5:45 Speaker 2: massive black hole would be a natural laboratory for testing

5:48 Speaker 2: Einstein's series in the most extreme conditions possible. It could

5:52 Speaker 2: also help us understand things like the massive Sagittarius astar,

5:56 Speaker 2: the geometry of space time near a supermassive black hole,

6:00 Speaker 2: and potentially even offer clues about dark matter.

6:03 Speaker 1: Now it's important to be clear this is still a candidate.

6:07 Speaker 1: The team published their findings in the Astrophysical Journal, and

6:10 Speaker 1: Breakthrough Listen has released all the observational data publicly, so

6:14 Speaker 1: researchers around the world can do independent analyses. Confirmation will

6:18 Speaker 1: require extensive follow up observations, but the scientific community is buzzing.

6:23 Speaker 1: This is the kind of discovery that reshapes entire research programs.

6:27 Speaker 2: If it holds up, keep watching the skies and the

6:30 Speaker 2: galactic center. This story is far from over.

6:34 Speaker 1: So we've talked about what's happening in Florida tonight and

6:36 Speaker 1: what might be happening at the center of our galaxy.

6:39 Speaker 1: Now let's zoom all the way out farther than you've

6:43 Speaker 1: probably ever thought about, and ask how does the universe end?

6:47 Speaker 2: For most of the past few decades, the scientific consensus

6:51 Speaker 2: has been pretty clear the universe expands forever. Dark energy,

6:56 Speaker 2: that mysterious force making up roughly sixty eight percent of

7:00 Speaker 2: the mass and energy in the cosmos, was thought to

7:03 Speaker 2: be a constant, relentlessly pushing everything apart. Eventually, galaxies would

7:08 Speaker 2: drift so far from each other that the night sky

7:11 Speaker 2: would go dark, stars would burn out, everything would fade

7:15 Speaker 2: into a cold, silent void. Scientists call this the Big

7:19 Speaker 2: Freeze or heat.

7:20 Speaker 1: Death, but new data is challenging that picture in a

7:24 Speaker 1: dramatic way. Physicist Henry Tie at Cornell University has published

7:28 Speaker 1: new calculations using data from two of the world's most

7:32 Speaker 1: powerful dark energy observatories, the Dark Energy Survey in Chile

7:36 Speaker 1: and the Dark Energy Spectroscopic Instrument in Arizona, and his

7:40 Speaker 1: conclusion is striking. The universe may be heading not for

7:44 Speaker 1: a frieze, but for a crunch.

7:46 Speaker 2: Here's how it works. Both surveys are finding evidence that

7:50 Speaker 2: dark energy isn't actually constant. It appears to be weakening

7:54 Speaker 2: over time. If that's true, then the force pushing the

7:57 Speaker 2: universe apart is gradually fading, and at some point gravity

8:01 Speaker 2: takes over. The expansion slows, stops, and then reverses Everything

8:07 Speaker 2: that has been flying apart for billions of years, begins

8:10 Speaker 2: falling back together.

8:12 Speaker 1: A TIES model introduces a hypothetical particle called an ultra

8:16 Speaker 1: light axion, combined with what's known as a negative cosmological

8:21 Speaker 1: constant to explain how dark energy could behave this way.

8:25 Speaker 1: The math suggests the universe is currently about thirteen point

8:29 Speaker 1: eight billion years old and approaching the halfway point of

8:33 Speaker 1: its total lifespan. It would continue expanding for roughly another

8:37 Speaker 1: eleven billion years, reach its maximum size, and then begin

8:42 Speaker 1: to contract, ultimately collapsing into a single point of unimaginable density.

8:48 Speaker 1: The Big crunch total elapsed time approximately thirty three billion years.

8:54 Speaker 2: Now before anyone starts updating their bucket lists, this is

8:57 Speaker 2: one model. It's not yet scientific senses. There's healthy debate

9:02 Speaker 2: about how to interpret the dark energy data, and upcoming

9:05 Speaker 2: messions from the European Space Agency's EUCLID Telescope, NASA SPHEREx

9:10 Speaker 2: project and the Veraice Reuben Observatory will provide much better

9:14 Speaker 2: measurements over the coming years.

9:16 Speaker 1: But the very fact that two independent observatories, one in

9:20 Speaker 1: the southern hemisphere one in the northern are converging on

9:24 Speaker 1: similar results about dark energy evolving. That's significant. As TI

9:29 Speaker 1: himself put it, for the last twenty years, people believed

9:33 Speaker 1: the universe would expand forever. The new data may be

9:37 Speaker 1: telling us something very different.

9:39 Speaker 2: The universe might be mortal after all. Quite the thought

9:43 Speaker 2: to sit with on a Thursday evening.

9:45 Speaker 1: And now, because apparently one existential revelation isn't enough for

9:50 Speaker 1: one episode, let's talk about City Killer asteroids.

9:55 Speaker 2: Those two words together are doing a lot of work.

9:57 Speaker 1: They really are so. At the American Association for the

10:01 Speaker 1: Advancement of Science conference in Arizona this week, NASA's Planetary

10:06 Speaker 1: Defense Officer, and yes, that is a real job title,

10:10 Speaker 1: Doctor Kelly Fast, gave a presentation that's been making headlines

10:15 Speaker 1: ever since, and for good reason.

10:18 Speaker 2: Doctor Fast explained that when it comes to asteroids, there

10:21 Speaker 2: are essentially three categories of concern. At the small end,

10:25 Speaker 2: things are hitting Earth all the time, meteors burning up

10:27 Speaker 2: in the atmosphere, the occasional fireball, We're not particularly worried

10:31 Speaker 2: about those. At the large end, the extinction level rocks

10:35 Speaker 2: the movie asteroid kind. Scientists are actually fairly confident about

10:40 Speaker 2: where those are. We track them, we know their orbits.

10:43 Speaker 1: It's the middle ground that keeps doctor fast up at night.

10:47 Speaker 1: Asteroids in the range of one hundred and forty meters

10:50 Speaker 1: and larger, large enough to devastate an entire city or

10:54 Speaker 1: a wide region, but small enough to be difficult to

10:58 Speaker 1: detect with current telescopes. Her estimate there are around twenty

11:02 Speaker 1: five thousand of these objects in the vicinity of Earth's orbit.

11:06 Speaker 2: And how many have we found about forty percent, meaning

11:10 Speaker 2: there are potentially fifteen thousand city killing space rocks out

11:14 Speaker 2: there right now that we simply do not know about.

11:17 Speaker 1: To add some context to that and to the challenge

11:20 Speaker 1: of actually doing something about it if we did spot one.

11:24 Speaker 1: Doctor Nancy Shabbitt, the planetary scientist who led NASA's Dart mission,

11:29 Speaker 1: the spacecraft that successfully changed the orbit of an asteroid

11:33 Speaker 1: back in twenty twenty two, was also at the conference.

11:36 Speaker 1: She pointed out that Dart was a breakthrough demonstration, but

11:40 Speaker 1: there isn't another one sitting on a launch pad ready

11:43 Speaker 1: to go.

11:43 Speaker 2: She specifically referenced the asteroid why Are four, which caused

11:48 Speaker 2: some anxiety earlier this year, with a small but not

11:52 Speaker 2: zero probability of a lunar impact in twenty thirty two.

11:56 Speaker 2: She said, if something like Why R four had been

11:59 Speaker 2: headed towards the Earth, we would not have any way

12:02 Speaker 2: to go and deflect it actively.

12:04 Speaker 1: Right now, the hope on the horizon is the Near

12:07 Speaker 1: Earth Object survey or telescope, which is planned for launch

12:11 Speaker 1: next year. Unlike conventional optical telescopes, it uses thermal infrared

12:16 Speaker 1: signatures to detect darker asteroids that are essentially invisible to

12:21 Speaker 1: conventional instruments, potentially a game changer for the detection side

12:25 Speaker 1: of the problem.

12:26 Speaker 2: But doctor Schabbot's point stands. Detection is one thing, having

12:31 Speaker 2: an active, ready to deploy deflection capability is another, and

12:35 Speaker 2: that investment, she says, is simply not being made at

12:38 Speaker 2: the level that needs to be something worth thinking about.

12:41 Speaker 2: Given that planetary defense is probably the one area of

12:44 Speaker 2: space science that is quite literally about survival.

12:48 Speaker 1: Sobering stuff. Let's come back down to Earth for a moment,

12:51 Speaker 1: or rather, let's look up from it.

12:54 Speaker 2: Here's something wonderful and wonderfully timely, because this one is

12:58 Speaker 2: happening right now to night as you listen.

13:01 Speaker 1: To this, Mercury, the innermost planet of our Solar system

13:04 Speaker 1: and the one most people have never actually seen with

13:08 Speaker 1: their own eyes, is tonight reaching what astronomers call its

13:11 Speaker 1: greatest eastern elongation. That's the point in its orbit where

13:15 Speaker 1: it's at its maximum angular distance from the Sun as

13:19 Speaker 1: seen from Earth, meaning it appears as far from the

13:22 Speaker 1: Sun in our sky as it ever gets.

13:24 Speaker 2: And why does that matter for observers because Mercury is

13:27 Speaker 2: normally incredibly difficult to spot. It's always close to the

13:31 Speaker 2: Sun in the sky, so you're either trying to catch

13:33 Speaker 2: it just before sunrise or just after sunset, with very

13:37 Speaker 2: little time before it follows the Sun below the horizon.

13:41 Speaker 2: But at greatest elongation you get the best window.

13:44 Speaker 1: Tonight, look to the western horizon shortly after sunset. Mercury

13:49 Speaker 1: will be visible as a moderately bright point of light,

13:52 Speaker 1: shining steadily rather than twinkling like a star. You won't

13:56 Speaker 1: need any special equipment, though binoculars will give you a

13:59 Speaker 1: much nicer view. This is Mercury's first greatest elongation of

14:03 Speaker 1: twenty twenty six, and the best evening viewing opportunity will

14:07 Speaker 1: get for the year so far.

14:09 Speaker 2: There's also a bonus tonight, the crescent moon, Saturn, and

14:12 Speaker 2: Neptune are all gathering in the same part of the sky,

14:15 Speaker 2: with Saturn and Neptune very close together near the western horizon. Now,

14:20 Speaker 2: Neptune will need a telescope and you'll need to wait

14:23 Speaker 2: until the sun is fully set. Do not point any

14:26 Speaker 2: optical instrument toward the horizon until the sun has cleared

14:29 Speaker 2: it completely. But the overall scene is really quite beautiful

14:33 Speaker 2: this evening.

14:34 Speaker 1: And for those of you keeping track of the upcoming

14:37 Speaker 1: six planet parade on the twenty eighth of February, Mercury

14:40 Speaker 1: reaching greatest elongation tonight is actually a key milestone in

14:44 Speaker 1: that build up. By the twenty eighth, Mercury will have

14:47 Speaker 1: improved its position enough to join Venus, Saturn, Jupiter, Uranus,

14:52 Speaker 1: and Neptune, all visible in the same sky. We'll have

14:56 Speaker 1: a full guide to that event closer to the date,

14:58 Speaker 1: but tonight is your previous go look west.

15:01 Speaker 2: And now to close out the episode, we have something

15:04 Speaker 2: that we absolutely love, a reminder that even on a

15:08 Speaker 2: space station in orbit, humans will find a way to celebrate.

15:12 Speaker 1: The crew of China's shen Zoo twenty one mission, currently

15:15 Speaker 1: living and working aboard the Tionggong space station, have released

15:19 Speaker 1: a music video to mark the lunar New Year, the

15:21 Speaker 1: Year of the Horse, and honestly it is delightful.

15:25 Speaker 2: Filming a music video in microgravity is, as you might imagine,

15:29 Speaker 2: a unique creative challenge. Everything floats, hair floats, props float,

15:35 Speaker 2: but the crew apparently embraced all of it, and the

15:37 Speaker 2: result is one of those lovely, warm, deeply human moments

15:41 Speaker 2: that cuts right through all the geopolitical complexity of the

15:45 Speaker 2: space race and reminds you that the people up there

15:48 Speaker 2: are just people celebrating a holiday with their families watching

15:51 Speaker 2: from below.

15:52 Speaker 1: Tionggong, which means Heavenly Palace, currently has a crew of

15:56 Speaker 1: three aboard. Following the shen Zu twenty one mission, has

16:00 Speaker 1: been steadily expanding its space station program, and moments like

16:04 Speaker 1: this one shared with the world are a reminder of

16:07 Speaker 1: why humans go to space in the first place, not

16:10 Speaker 1: just for science or national prestige, but for the sheer

16:14 Speaker 1: joy of being up there.

16:16 Speaker 2: Don sifa chai to all of our listeners celebrating the

16:18 Speaker 2: lunar new Year. May the Year of the Horse bring

16:21 Speaker 2: you good fortune and hopefully fewer hydrogen leaks.

16:26 Speaker 1: And on that note, that's your Astronomy Daily for Thursday,

16:30 Speaker 1: February nineteenth, twenty twenty six. What a lineup today? A

16:35 Speaker 1: live rocket fueling test a cosmic clock near a black hole,

16:39 Speaker 1: the possible end of the universe, city killing asteroids, mercury

16:44 Speaker 1: in the evening sky, and a music video from Orbit.

16:48 Speaker 2: If you want to follow along with the Artemis two

16:50 Speaker 2: fueling test tonight, NASA has a live stream at NASA

16:53 Speaker 2: dot gov. We'll link everything in the show notes, and

16:56 Speaker 2: if you spot mercury tonight, tag us on social media

16:59 Speaker 2: at hame stro Daily Pod. We would love to see

17:02 Speaker 2: your photos.

17:03 Speaker 1: Subscribe, leave a review if you're enjoying the show, and

17:06 Speaker 1: we will be back tomorrow with the results of tonight's

17:09 Speaker 1: fueling test. Until then, keep looking up clear skies everyone, Sunny.

17:15 Speaker 2: Day star ist so starst