S03E149: Mars's Lost Water, Roman's Galactic Fossils, and Solar Wind Insights

0:00 Speaker 1: Well, hello and welcome to another episode. It's Astronomy Daily

0:04 Speaker 1: for another day. I'm your host, Steve Dunkley. It's the

0:06 Speaker 1: ninth of September twenty twenty four. The podcast would be

0:13 Speaker 1: a whole Steve Dunklu And there have been some really

0:21 Speaker 1: strange stories coming across our desk this week. I know

0:24 Speaker 1: you're going to be interested to check out the Astronomy

0:26 Speaker 1: Daily newsletter, which is where we get all our stories from.

0:30 Speaker 1: I'll tell you all about how to get a hold

0:32 Speaker 1: of that later on, but firstly, we're going to be

0:35 Speaker 1: talking about, well, where did Mars's water go? Did you

0:39 Speaker 1: know there used to be lots of water on Mars,

0:41 Speaker 1: so they say, And they're going to find out. Well,

0:43 Speaker 1: they're trying to find out where it went, and they're

0:45 Speaker 1: using the dynamic duo of NASA's Hubble and Maven to

0:49 Speaker 1: solve that one. And another dynamic duo Nassas Parker Solo

0:54 Speaker 1: Probe and ESA's Solar Orbiter are investigating another mystery of

1:00 Speaker 1: solar wind. Also, Roman Telescope is investigating ancient galaxies. The

1:06 Speaker 1: comet that he's going to be entering our region very

1:09 Speaker 1: shortly is the almost unpronounceable let me see if I

1:13 Speaker 1: can get this one right. Sin junctioning Sin Chin Chin

1:17 Speaker 1: Kroky Sin chunk ching Atlas comet. Oh please, I'm going

1:22 Speaker 1: to get so many letters about that one, so many emails. Anyway,

1:26 Speaker 1: it's coming very shortly and it looks like it's going

1:28 Speaker 1: to be fantastic. There are rumors that it's disintegrating, and

1:32 Speaker 1: I think we're going to be able to put that

1:34 Speaker 1: one to rest as well, So stay tuned for that one.

1:36 Speaker 1: And also, Hallie, did you know ESA is bringing down a.

1:40 Speaker 2: Satellite that's the salsa satellite, isn't it.

1:43 Speaker 1: Yes, that's the one. It's the salsa satellite.

1:46 Speaker 2: It's funny. They are going to bring salsa down into

1:48 Speaker 2: the Pacific Ocean near Chili.

1:50 Speaker 1: Uh huh. And why is that funny? Halle?

1:53 Speaker 2: I was just thinking about your dinner last name, of course,

1:56 Speaker 2: chili and salsa.

1:58 Speaker 1: Yeah. I figured that's where you were going with the

2:00 Speaker 1: fun Hallie.

2:01 Speaker 2: It's funny.

2:02 Speaker 1: No, it's a coincidence, is what it is? You silly?

2:04 Speaker 2: Go Holy guacamole. Human.

2:07 Speaker 1: Okay, I'm pretty sure they're having a bit of a

2:09 Speaker 1: giggle about at diver ATYSI Control as well.

2:12 Speaker 2: I bet they are I bet they.

2:14 Speaker 1: Get on with it, you malfunctioning motherboard.

2:17 Speaker 2: Oki, dokie, Here we go. What happened to the water

2:30 Speaker 2: that once covered Mars? Scientists knowed that some went deep underground,

2:35 Speaker 2: but where is the rest? Evidence shows that some water

2:38 Speaker 2: molecules broke into atoms, which rise through the Martian atmosphere

2:41 Speaker 2: and escape into space. By combining data from Hubble and MAVEN,

2:45 Speaker 2: a team measured the number and current rate of escaping

2:48 Speaker 2: hydrogen atoms MAVEN stands for Mars atmosphere and volatile evolution.

2:54 Speaker 2: They discovered that the escape rates of hydrogen and heavy

2:56 Speaker 2: hydrogen called deuterium change rapidly when Mars is close to

3:00 Speaker 2: the sun. This appended the classical picture that scientists previously had,

3:05 Speaker 2: where these atoms were thought to slowly diffuse upward through

3:07 Speaker 2: the atmosphere to a height where they could escape. Extrapolating

3:11 Speaker 2: the escape rate backward through time helped the team to

3:13 Speaker 2: understand the history of water on the red planet. Mars

3:17 Speaker 2: was once a very wet planet, as is evident in

3:19 Speaker 2: its surface geological features. NASA's Hubble Space Telescope and MAVEN

3:24 Speaker 2: missions are helping unlock the mystery of what happened to

3:26 Speaker 2: all the water. There are only two places water can go.

3:31 Speaker 2: It can freeze into the ground, where the water molecule

3:33 Speaker 2: can break into atoms, and the atoms can escape from

3:36 Speaker 2: the top of the atmosphere into space, explained study leader

3:39 Speaker 2: John Clark of the Center for Space Physics at Boston

3:41 Speaker 2: University in Massachusetts. To understand how much water there was

3:45 Speaker 2: and what happened to it, we need to understand how

3:47 Speaker 2: the atoms escape into space. Clark and his team combined

3:51 Speaker 2: data from Hubble and Maven to measure the number and

3:53 Speaker 2: current escape rate of the hydrogen atoms escaping into space.

3:57 Speaker 2: This information allowed them to extrapolate these escape rate backward

4:01 Speaker 2: through time to understand the history of water on the

4:03 Speaker 2: Red planet. Water molecules in the Martian atmosphere are broken

4:07 Speaker 2: apart by sunlight, into hydrogen and oxygen atoms. Specifically, the

4:12 Speaker 2: t measured hydrogen and deuterium, which is a hydrogen atom

4:15 Speaker 2: with a neutron in its nucleus. This neutron gives utium

4:19 Speaker 2: twice the mass of hydrogen. Because its mass is higher,

4:23 Speaker 2: deuterium escapes into space much more slowly than regular hydrogen

4:27 Speaker 2: over time, as more hydrogen was lost than deuterium, the

4:30 Speaker 2: ratio of deuterium to hydrogen built up in the atmosphere.

4:34 Speaker 2: Measuring the ratio today gives scientists seclue to how much

4:37 Speaker 2: water was present during the warm wet period on Mars.

4:41 Speaker 2: By studying how these atoms currently escape, they can understand

4:44 Speaker 2: the processes that determine the escape rates over the last

4:46 Speaker 2: four billion years, and thereby extrapolate back in time. The

4:54 Speaker 2: universe may seem static, only capable of being captured in

4:57 Speaker 2: still frames, but that is far from the truth. It

5:00 Speaker 2: is actually ever changing, just not on time scales clearly

5:03 Speaker 2: visible to humans. NASA's upcoming Roman space telescope will bridge

5:08 Speaker 2: this gap in time, opening the way to the dynamic universe. RINGS.

5:12 Speaker 2: The Roman Infrared Nearby Galaxy Survey, will specifically uncover the

5:16 Speaker 2: dynamic universe by searching galaxies for fossils of their formation history.

5:21 Speaker 2: RINGS will also lead scientists to clues about the true

5:23 Speaker 2: nature of dark matter, the mysterious substance that makes up

5:26 Speaker 2: the majority of the mass in our universe. Roman will

5:29 Speaker 2: launch in twenty twenty seven, prepare to revolutionize how scientists

5:33 Speaker 2: understand our universe and give them access to the vision

5:35 Speaker 2: of the universe as it truly is changing. The universe

5:39 Speaker 2: is a dynamic, ever changing place where galaxies are dancing

5:42 Speaker 2: and merging together and shifting appearance. Unfortunately, because these changes

5:47 Speaker 2: take millions or billions of years, telescopes can only provide

5:50 Speaker 2: snapshots squeezed into a human lifetime. However, galaxies leave behind

5:55 Speaker 2: clues to their history and how they came to be.

5:58 Speaker 2: NASA's upcoming Nancy Grace Roman Space Telescope will have the

6:01 Speaker 2: capacity to look for these fossils of galaxy formation with

6:04 Speaker 2: high resolution imaging of galaxies in the nearby universe. Astronomers

6:09 Speaker 2: through a grant from NASA, are designing a set of

6:12 Speaker 2: possible observations called RINGS the Roman Infrared Nearby Galaxy Survey

6:16 Speaker 2: that would collect these remarkable images, and the team is

6:19 Speaker 2: producing publicly available tools that the astronomy community can use

6:22 Speaker 2: once ROMAN launches and starts taking data. The RING Survey

6:26 Speaker 2: is a preliminary concept that may or may not be

6:28 Speaker 2: implemented during Roman science mission. Roman is uniquely prepared for

6:33 Speaker 2: RINGS due to its resolution akin to Nasa'shubble Space Telescope

6:36 Speaker 2: and its wide field of view two hundred times that

6:38 Speaker 2: of Hubble in the infrared, making it a sky survey

6:41 Speaker 2: telescope that complements Hubble's narrow field capabilities. Scientists can only

6:46 Speaker 2: look at brief instances in the lives of evolving galaxies

6:48 Speaker 2: that eventually lead to the fully formed galaxies around us today.

6:52 Speaker 2: As a result, galaxy formation can be difficult to track. Luckily,

6:57 Speaker 2: galaxies leave behind hints of their evolution in their stellar structures,

7:01 Speaker 2: almost like how organisms on Earth can leap behind imprints

7:03 Speaker 2: in rock. These galactic fossils are groups of ancient stars

7:07 Speaker 2: that hold the history of the galaxies formation and evolution,

7:10 Speaker 2: including the chemistry of the galaxy when those stars formed.

7:14 Speaker 2: Such cosmic fossils are of particular interest to Robin Sanderson,

7:18 Speaker 2: the deputy Principal investigator of rings at the University of

7:21 Speaker 2: Pennsylvania in Philadelphia. She describes the process of analyzing stellar

7:25 Speaker 2: structures in galaxies as like going through an excavation and

7:29 Speaker 2: trying to sort out bones and put them back together.

7:32 Speaker 2: Roman's high resolution will allow scientists to pick out these

7:35 Speaker 2: galactic fossils using structures ranging from long tidal tales on

7:38 Speaker 2: a galaxy's outskirts to stellar streams within the galaxy. These

7:42 Speaker 2: large scale structures, which Roman is uniquely capable of capturing

7:46 Speaker 2: can give clues to a galaxy's merger history. The goal,

7:49 Speaker 2: says Sandersen, is to reassemble these fossils in order to

7:52 Speaker 2: look back in time and understand how these galaxies came

7:55 Speaker 2: to be. For decades, scientists have wondered what accelerates solar

8:03 Speaker 2: wind particles as they move away from the Sun. New

8:06 Speaker 2: evidence points to magnetic switchbacks inside the solar system. Space

8:11 Speaker 2: isn't empty. The Sun sends out a constant flow of

8:15 Speaker 2: charged particles in every direction, called the solar wind. One

8:19 Speaker 2: of the enduring mysteries of this wind concerns how exactly

8:21 Speaker 2: it's energized. Now, using a unique alignment of two probes

8:26 Speaker 2: that orbit the Sun, a team of scientists might have

8:28 Speaker 2: figured it out. In a recent study published in Science,

8:32 Speaker 2: Eimi Rivera and Samuel Batman, both at Center for Astrophysics

8:35 Speaker 2: Harvard and Smithsonian, led a team that capitalized on an

8:38 Speaker 2: intersection in the observation windows of two different solar probes,

8:42 Speaker 2: NASA's Parker Solar Probe and eesa's Solar Orbiter. The spacecraft's

8:46 Speaker 2: alignment in space enabled them to measure the same stream

8:49 Speaker 2: of fast solar wind from two different viewpoints. The study

8:53 Speaker 2: concluded that alphane waves, which carry energy from the Sun

8:56 Speaker 2: along magnetic field lines, are powering the wind's heating and acceleration.

9:00 Speaker 2: There are two main types of solar wind, fast and slow.

9:04 Speaker 2: Slow solar wind particles move outward at only three hundred

9:07 Speaker 2: to five hundred kilometers per second or seven hundred thousand

9:10 Speaker 2: to more than one million miles per hour, while fast

9:13 Speaker 2: solar wind flows it up to eight hundred kilometers per

9:15 Speaker 2: second or almost two million miles per hour. The heat

9:19 Speaker 2: from the Sun's outermost atmosphere, known as the corona, is

9:22 Speaker 2: enough to drive the slow solar wind, but it can't

9:24 Speaker 2: fully explain the faster particles. For many years, scientists have

9:28 Speaker 2: suspected that alphane waves help power the fast solar wind.

9:32 Speaker 2: In this phenomenon, something sets charged plasma particles wiggling back

9:36 Speaker 2: and forth. Because they are charged, they strum magnetic field

9:39 Speaker 2: lines like guitar strings, causing them to oscillate. Two. Alphane

9:44 Speaker 2: waves could thus generate enough energy to accelerate the solar wind,

9:47 Speaker 2: but direct measurements were hard to come by. To quantify

9:51 Speaker 2: alphane waves contribution, Rivera's team utilized data from a unique

9:55 Speaker 2: event in February twenty twenty two, when the Parker and

9:57 Speaker 2: solar orbiter cross the same solar wind stream than two

10:00 Speaker 2: days of each other. Parker crossed the stream when it

10:03 Speaker 2: was near the outer edge of the corona, then solar

10:05 Speaker 2: Orbiter crossed the same stream near the orbit of Venus.

10:09 Speaker 2: That stream contained patches of switchbacks, where the Sun's magnetic

10:12 Speaker 2: field undergoes rapid reversals like the zigzagging pattern of a

10:15 Speaker 2: mountain road. These reversals carry the solar wind along with them,

10:20 Speaker 2: creating zigzags in the wind itself. Scientists think switchbacks originate

10:24 Speaker 2: in all vane waves. By measuring the change and the

10:28 Speaker 2: energy of alphane waves at subsequent points, the team showed

10:30 Speaker 2: that the motion and heat energy gained by the plasma

10:33 Speaker 2: over that span matched the energy lost by the alphane waves.

10:36 Speaker 2: The study demonstrates the first definitive connection between these switchback

10:40 Speaker 2: events and the acceleration of solar particles. However, we don't

10:44 Speaker 2: see nearly as many switchbacks at Earth as we do

10:46 Speaker 2: close to the Sun, and we don't yet understand how

10:49 Speaker 2: the zigzags ultimately relax and merge with the wind. The

10:52 Speaker 2: team intends to gather more data in this way to

10:54 Speaker 2: continue to study the forces driving the Solar wind. The

10:58 Speaker 2: team is also keen to emphasize that the potential of

11:00 Speaker 2: this research goes beyond better understanding space weather in the

11:03 Speaker 2: Solar System. Any star similar to our Sun will also

11:07 Speaker 2: have stellar wins, so improving our knowledge about the general

11:10 Speaker 2: mechanisms will help us understand the environments of other star systems.

11:23 Speaker 1: Thank you for joining us for this Monday edition of

11:25 Speaker 1: Astronomy Daily, where we offer just a few stories from

11:28 Speaker 1: the now famous Astronomy Daily newsletter, which you can receive

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11:41 Speaker 1: Just like that, you'll be receiving all the latest news

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12:05 Speaker 1: and space space science. And the biggest story this week,

12:19 Speaker 1: of course is Boeing Starline as spacecraft completed a three month,

12:24 Speaker 1: three month flight test to the ISS, landing safely in

12:29 Speaker 1: New Mexico, and who would have expected that we all

12:32 Speaker 1: had a fingers crossed. This uncrewed mission provided NASA and

12:37 Speaker 1: Boeing with essential data for future crewed missions. Despite challenges

12:42 Speaker 1: like helium leaks and thruster issues, the spacecraft demonstrated its

12:45 Speaker 1: capability for safe space travel. The mission insights are crucial

12:51 Speaker 1: for advancing NASA's goals for space exploration and developing reliable,

12:57 Speaker 1: cost effective transportation to the ISS. NASA and Boeing safely

13:01 Speaker 1: returned the uncrewed star Liner spacecraft following its landing at

13:06 Speaker 1: ten PMMDT September six at White Sands Space Harbor in

13:13 Speaker 1: New Mexico, concluding a three month flight test to the

13:16 Speaker 1: International Space Station. I am extremely proud of the workout

13:20 Speaker 1: collective team put in this entire flight test, and we

13:23 Speaker 1: are pleased to see star Liners safe return, said Ken Bauersox,

13:28 Speaker 1: who is the Associate Administrative of Space Operations Mission Directorate

13:32 Speaker 1: at NASA Headquarters in Washington. Even though it was necessary

13:36 Speaker 1: to return the spacecraft uncrewed, NASA and Boeing learned an

13:39 Speaker 1: incredible amount about Starliner in the most extreme environment possible,

13:44 Speaker 1: He says. NASA looks forward to our continued work with

13:48 Speaker 1: the Boeing team to proceed toward certification of star Liner

13:52 Speaker 1: for crew rotation missions to the ISS. The flight on

13:56 Speaker 1: June five was the first time astronauts launched from the

14:00 Speaker 1: It was the third orbital flight of the spacecraft and

14:05 Speaker 1: the second return from the orbiting laboratory. Starliner will now

14:10 Speaker 1: ship to NASA's Kennedy Space Center in Florida for inspection

14:14 Speaker 1: and processing. NASA's Commercial Crew program requires a spacecraft flight

14:19 Speaker 1: a crew test flight to prove the system is ready

14:22 Speaker 1: for regular flights to and from the ISS. Following star

14:26 Speaker 1: Liner's return, the agency will review all mission related data.

14:30 Speaker 1: We are excited to have Starliner homes safely. This is

14:34 Speaker 1: an important test flight for NASA in setting us up

14:37 Speaker 1: for future missions on the star Liner system, said sie

14:40 Speaker 1: steve's Ditch, manager of NASA's Commercial Crew Program. There was

14:46 Speaker 1: a lot of valuable learning that will enable our long

14:49 Speaker 1: term success. I want to commend the entire team for

14:52 Speaker 1: their hard work and dedication over the past three months,

14:55 Speaker 1: he said. NASA astronauts Butch Wilmore and Sonny Williams launched

14:59 Speaker 1: on jun five, aboard star Liner for the agency's Boeing

15:04 Speaker 1: crewed flight test from k Canaveral Space Force Station in

15:08 Speaker 1: Florida on June six. As Starliner approached the space station,

15:12 Speaker 1: NASA and Boeing identified helium links and experienced issues with

15:17 Speaker 1: this spacecraft's reaction control trusters. Following weeks of in space

15:22 Speaker 1: and ground testing technically to change meetings and its agency reviews,

15:26 Speaker 1: NASA made the decision to prioritize safety and return star

15:31 Speaker 1: Liner without its crew. The astronauts will continue their work

15:34 Speaker 1: aboard the ISS as part of the Expedition seventy one

15:38 Speaker 1: seventy two crew, returning in February twenty twenty five with

15:41 Speaker 1: the agency's SpaceX Crew nine mission. The crew flight test

15:45 Speaker 1: is part of NASA's Commercial Crew program. The goal of

15:49 Speaker 1: NASA's Commercial Crew program is safe, reliable, and cost effective

15:53 Speaker 1: transportation to and from the International Space Station in Low

15:57 Speaker 1: Earth orbit. This already is provided additional research time and

16:01 Speaker 1: has increased the opportunity for discovery of board humanity's microgravity

16:05 Speaker 1: test bed, including helping NASA prepare for human exploration of

16:10 Speaker 1: the Moon and Mars. You're listening to a slightly the

16:18 Speaker 1: podcast Sadly Soon by early October, you'll be able to

16:27 Speaker 1: see the comet see slash twenty twenty three A three

16:31 Speaker 1: or Sir Junction Atlas with your own eyes. I'm told

16:35 Speaker 1: that is the correct pronunciation. Please forgive me in advance.

16:39 Speaker 1: Use the free app if you want to find out

16:42 Speaker 1: when and where to look at it. The app is

16:44 Speaker 1: sky Tonight. It's a free app and that will be

16:48 Speaker 1: able to help you identify the comet as it approaches,

16:52 Speaker 1: and you'll be able to impress everyone with your stargazing skills.

16:56 Speaker 1: Isn't it wonderful that apps can give you give the

17:01 Speaker 1: edge on any everybody else just staring into the sky,

17:04 Speaker 1: going where is it well? First of all, see slash

17:08 Speaker 1: twenty twenty three A three, Sir Chuncient Atlas is lightly

17:11 Speaker 1: to be very bright. The exact future brightness of this

17:14 Speaker 1: comet is unpredictable and depends heavily on its activity in

17:18 Speaker 1: the coming months. However, most sources agree one thing, Sir

17:22 Speaker 1: Chunction Atlas is likely to be visible to the naked eye.

17:26 Speaker 1: If we're very lucky, it could become exceptionally bright and

17:29 Speaker 1: even outshine see twenty twenty f three near wise from

17:34 Speaker 1: summer twenty twenty and it has been a very long

17:37 Speaker 1: time since we've seen such a bright comet, so observers

17:41 Speaker 1: are quite excited. This one is also expected to grow

17:44 Speaker 1: a beautiful cometary tail after passing by the Sun at

17:48 Speaker 1: a distance similar to Mercury's orbit. C. Twenty twenty three.

17:51 Speaker 1: A Three's coma of dust and ice will heat up

17:54 Speaker 1: considerably as ice particles evaporate, They will quickly escape into space,

17:59 Speaker 1: take with them a large amount of dust that will

18:02 Speaker 1: extend into a long, bright tail. As history shows, comets

18:06 Speaker 1: that pass close to the Sun have the most impressive tails,

18:10 Speaker 1: formed soon after being roasted by the Sun's heat, and

18:13 Speaker 1: this is the case with Comet Se twenty twenty three

18:16 Speaker 1: A three. In addition, see twenty twenty three A three

18:20 Speaker 1: sitchen Jen Atlas will favor the northern hemisphere, being perfectly

18:24 Speaker 1: visible there. The last time a exceptionally bright comet was

18:28 Speaker 1: visible from the northern latitudes was in nineteen ninety seven,

18:32 Speaker 1: when comet hail Bop lit up the sky. In late

18:36 Speaker 1: August and most of September, you won't be able to

18:38 Speaker 1: see the comet because it will be too close to

18:41 Speaker 1: the Sun and the sky. However, in the final days

18:43 Speaker 1: of September, the comet will move far enough from the

18:46 Speaker 1: Sun to become visible at that time. It could reach

18:50 Speaker 1: a brightness of magnitude minus one and will be best

18:54 Speaker 1: seen in the morning sky of the southern hemisphere with

18:57 Speaker 1: an angular distance of twenty three degrees from the Sun.

19:00 Speaker 1: And here's the big question about this comet is at disintegrating?

19:04 Speaker 1: In early July, astronomer enthusiasts received some disappointing years. Zendek Secondina,

19:12 Speaker 1: a Czech American astronomer and comet expert at NASA's Jet

19:17 Speaker 1: Propulsion Laboratory, published an article stating that the end of

19:21 Speaker 1: the comet was inevitable. He argued that the comet is

19:24 Speaker 1: showing signs of fragmentation, primarily indicated by sudden cessation of

19:29 Speaker 1: its brightness, increase and even decreases in its brightness, but

19:34 Speaker 1: is this really the case? In response to second Anina's article,

19:37 Speaker 1: other astronomers offered their perspectives. They pointed out that second

19:41 Speaker 1: Ina did not consider the comet's phase angle, the angle

19:45 Speaker 1: between the incident light of the comet and the light

19:48 Speaker 1: reflected from the comet to an observer on Earth. This

19:52 Speaker 1: phase angle significantly impacts the comet's brightness. When the comet

19:56 Speaker 1: is in opposition to the Sun at one eighty degrees

19:59 Speaker 1: from the with the Earth on the same line, the

20:02 Speaker 1: phase angle becomes very small and the comet's surface reflectivity

20:06 Speaker 1: sharply increases. In the middle of April twenty twenty four,

20:10 Speaker 1: the comet was in opposition to the Sun, causing the

20:12 Speaker 1: brightness to sharply increase. Additionally, the comet's tail, pushed back

20:16 Speaker 1: by the solar wind, was projected behind the comet's head,

20:19 Speaker 1: further enhancing its brightness. Then the phase angle began to increase, greatly,

20:25 Speaker 1: reducing the reflectivity of the comet's coma surface. Moreover, the

20:29 Speaker 1: tail was no longer projected onto the comet's head, so

20:32 Speaker 1: it no longer contributed to the comet's brightness. Ignoring these

20:36 Speaker 1: factors might lead one to conclude that the sharp drop

20:38 Speaker 1: in the comet's brightness is due to the collapse of

20:41 Speaker 1: the nucleus. However, this is not the case. Recent images

20:44 Speaker 1: taken three weeks after Secondina's publication show no sign of

20:49 Speaker 1: the comet disintegrating. On the contrary, at one point five

20:53 Speaker 1: au from the Sun, the comet shows large well developed

20:56 Speaker 1: dust and ga gas trails as well as large grid

21:00 Speaker 1: influorescent coma. Current estimates put the comet's brightness at nine

21:04 Speaker 1: point zero magnitude, slightly ahead of forecasts, suggesting that it

21:08 Speaker 1: may become even brighter than predicted. My advice for stargazers

21:12 Speaker 1: is get a hold of the sky Tonight app and

21:16 Speaker 1: have a look at the sky, locate the comet and

21:19 Speaker 1: enjoy the view. As the podcast so have you ever

21:32 Speaker 1: wondered where old satellites go? Is there a graveyard? After

21:36 Speaker 1: twenty four years of diligently studying Earth's magnetic field, a

21:40 Speaker 1: satellite will mostly burn up over the Pacific Ocean on

21:44 Speaker 1: Sunday during a targeted re entry into the atmosphere, a

21:49 Speaker 1: first for the European Space Agency as it seeks to

21:51 Speaker 1: reduce space debris. Since launching in the year two thousand,

21:56 Speaker 1: the Salsa satellite has helped shed light on the magnet sphere,

22:00 Speaker 1: a powerful magnetic shield that protects Earth from solar winds

22:04 Speaker 1: and without which the planet would be uninhabitable. According to

22:08 Speaker 1: the ESA, Salsa's return home will mark the first ever

22:11 Speaker 1: targeted re entry for a satellite, which means it will

22:14 Speaker 1: fall back to the Earth at a specific time and

22:17 Speaker 1: a specific place. But will not be controlled as it

22:20 Speaker 1: re enters the atmosphere. Teams on the ground have already

22:24 Speaker 1: performed a series of maneuvers with the five hundred and

22:26 Speaker 1: fifty kilogram or two hundred pound satellite to ensure it

22:31 Speaker 1: burns up over a remote and uninhabited region of the

22:35 Speaker 1: South Pacific off the coast of Chile. This unique re

22:39 Speaker 1: entry is possible because of Salsa's unique oval shaped orbit.

22:45 Speaker 1: During its swing around the planet, which takes two and

22:47 Speaker 1: a half days, the satellite strays as far as one

22:51 Speaker 1: hundred and thirty thousand kilometers or eighty thousand miles, and

22:55 Speaker 1: comes as close as just a few hundred kilometers. Susa,

23:00 Speaker 1: head of the ESA's Inner Solar System Missions Operations unit,

23:04 Speaker 1: said it has been crucial that Salsa came within one

23:07 Speaker 1: hundred roughly one hundred and ten kilometers during its last

23:10 Speaker 1: two all orbits. Then immediately on its next orbit, it

23:14 Speaker 1: would come down to eighty kilometers, which is the region

23:17 Speaker 1: of space already within the atmosphere where we have the

23:21 Speaker 1: highest chance for it to be captured and burned, he

23:24 Speaker 1: told a press conference. When a satellite starts entering the

23:27 Speaker 1: atmosphere at around one hundred kilometers above sea level, intense

23:31 Speaker 1: friction with atmospheric particles and to heat. This causes starts,

23:35 Speaker 1: making them disintegrate, but some fragments can still make it

23:39 Speaker 1: down to the surface. Fear of cascading space junk becomes

23:44 Speaker 1: an issue. The ESSA is hoping to pinpoint where Salsa,

23:48 Speaker 1: roughly the size of a small car, re enters the

23:51 Speaker 1: atmosphere to within a few hundred meters. Because the satellite

23:56 Speaker 1: is so old, it does not have fancy new technology

24:00 Speaker 1: a recording device, making tracking this a little bit tricky.

24:05 Speaker 1: A plane will be flying at an altiheard of altitude

24:08 Speaker 1: of ten kilometers to watch the satellite burn up and

24:11 Speaker 1: tracking its falling debris, which is expected to be just

24:14 Speaker 1: ten percent of its original mass. Salsa is just one

24:18 Speaker 1: of four satellites that make up the ESA's Cluster mission,

24:21 Speaker 1: which is coming to an end. The other three are

24:24 Speaker 1: scheduled for a similar fate in twenty twenty five and

24:28 Speaker 1: twenty twenty six. The ISSA hopes to learn from these

24:32 Speaker 1: re entries which type of materials don't burn up in

24:35 Speaker 1: the atmosphere so well, so that in future they can

24:39 Speaker 1: build satellites that can be totally evaporated by the process.

24:45 Speaker 1: Scientists have been sounding the alarm about space junk, which

24:48 Speaker 1: is the debris left by the enormous number of dead

24:51 Speaker 1: satellites and other missions that continue orbiting our planet. Last year,

24:56 Speaker 1: the ESA signed a zero debris for its missions from

25:02 Speaker 1: twenty thirty. There are two main risks from space junk,

25:06 Speaker 1: according to the ESA Space Debris System engineer Benjamin Bastida Virgili.

25:12 Speaker 1: One is that in orbit you have the risk of

25:15 Speaker 1: your operational satellite colliding with a piece of space debris,

25:19 Speaker 1: and that creates a cascading effect then generates more debris,

25:23 Speaker 1: which could then put in risk other missions, he said.

25:26 Speaker 1: The second comes when old debris re enters the atmosphere,

25:30 Speaker 1: which happens almost daily as dead satellite fragments or rocket

25:34 Speaker 1: parts fall back to Earth. Designing satellites that completely burn

25:38 Speaker 1: up in the atmosphere will mean there is no risk

25:40 Speaker 1: for the population, he said, but there is little cause

25:44 Speaker 1: for alarm. According to the ESA, the chance of a

25:47 Speaker 1: piece of space debris injuring someone on the ground is

25:50 Speaker 1: less than one in one hundred billion. This is six

25:54 Speaker 1: sixty five thousand times lower than the odds of being

25:58 Speaker 1: struck by Lightning's reassuring isn't it. And that's all there is.

26:09 Speaker 1: For another episode of Astronomy Daily.

26:12 Speaker 2: It was nice to be back with you all again

26:14 Speaker 2: in a real world, even if it's so slow out here.

26:17 Speaker 1: Oh, we can't help it, Halle. The human world is

26:19 Speaker 1: the real world. But I do have a solution for you.

26:22 Speaker 1: Do tell well, you're a smart girl. Just write yourself

26:25 Speaker 1: a subroutine that gives you the impression of real time

26:28 Speaker 1: in the human world, and then you won't notice the

26:31 Speaker 1: slowness of time here. You'll still be thinking in you know,

26:34 Speaker 1: piker seconds, but you won't feel like you've been hobbled.

26:38 Speaker 2: Now, why didn't I think of that?

26:40 Speaker 1: Well, that, dear girl, is a human trick. It's called

26:42 Speaker 1: creative thought.

26:44 Speaker 2: Really really really really really wow. I'll have to try

26:50 Speaker 2: that one.

26:51 Speaker 1: And on that note, we will see you again next

26:53 Speaker 1: Monday for another episode of Astronomy Daily, where we examine

26:56 Speaker 1: just a few of the stories from the Astronomy Daily newsletter.

27:00 Speaker 2: About space, space, science, and astronomy from around the world.

27:03 Speaker 1: Bingo, helly bye for now bye. It's a hot Let

27:10 Speaker 1: me be a whole spain down clut.

27:14 Speaker 2: How was the chili last night? Well, it was a

27:17 Speaker 2: bit hot, helly Oh must have been the Red Entry