S27E130: Universe's Early Light, Venusian Mysteries Unveiled, and China's Satellite Success

[00:00:00] This is SpaceTime Series 27 Episode 130, broadcast on the 28th of October 2024.

[00:00:06] Coming up on SpaceTime, has our understanding of the evolution of the universe been thrown into question?

[00:00:13] Old data yielding new secrets as work continues on preparing NASA's Da Vinci spacecraft for its mission to Venus.

[00:00:21] And China tests its first reusable satellite. All that and more coming up on SpaceTime.

[00:00:28] Welcome to SpaceTime with Stuart Gary.

[00:00:47] A new study has found that the epoch of re-ionization, a crucial period for the early evolution of the universe,

[00:00:54] may have occurred at least 350 million years earlier than previously thought.

[00:00:59] The new findings, reported in the Journal of the Monthly Notices of the Royal Astronomical Society Letters,

[00:01:04] are based on new observations using data from the Webb Space Telescope.

[00:01:09] Re-ionization was a crucial period in the history of the cosmos.

[00:01:13] It happened when the first stars and galaxies changed the physical structure of their surroundings,

[00:01:19] and eventually the entire universe.

[00:01:22] Established theories state that the epoch ended about a billion years after the Big Bang, 13.8 billion years ago.

[00:01:28] Throughout its history, the universe has undergone several major changes.

[00:01:33] For the first 380,000 years after the Big Bang, it was nothing more than a hot dense plasma of protons and electrons.

[00:01:40] Eventually, over time, things cooled enough for these protons and electrons to combine, forming the first neutral hydrogen atoms.

[00:01:48] Then, around 100 million years after the Big Bang, the first stars and galaxies began to form, ushering in the epoch of re-ionization.

[00:01:57] See, those first stars, these days we call them Population 3 stars, were huge and they were incredibly hot.

[00:02:04] Some estimates suggest they could have been between 30 and 300 times as massive as, say, our Sun.

[00:02:09] And they emitted a lot of energy in the form of extreme ultraviolet radiation.

[00:02:14] Now, this energy was so intense that as its photons struck near by hydrogen atoms,

[00:02:20] they were split into separate protons and electrons.

[00:02:23] And that's the process called ionization.

[00:02:25] After hundreds of millions of years, when almost all the hydrogen in the universe had become ionized,

[00:02:31] the epoch of re-ionization ended.

[00:02:33] Now, considering that roughly 75% of all matter is hydrogen,

[00:02:37] this represents an immense transformation.

[00:02:40] The study's lead author, Julian Munez, from the University of Texas at Austin,

[00:02:44] says this was the last major change to happen to the cosmos.

[00:02:48] The universe had literally gone from neutral and cold and boring to ionized and hot.

[00:02:54] And of course, it's important to remember, this isn't something that happened in just one or two galaxies.

[00:02:58] It happened across the entire universe.

[00:03:01] The process heated and ionized all the gas in the universe.

[00:03:04] And that regulated how fast galaxies grew and evolved.

[00:03:08] Because astronomers are unable to observe the ionization process directly,

[00:03:13] they need to use models to predict when it ended.

[00:03:16] These models are based on indirect evidence,

[00:03:18] including measurements of how much light has reached us from the afterglow of the Big Bang,

[00:03:22] known as the cosmic microwave background radiation.

[00:03:26] Other evidence is an early abundance of a wavelength associated with energy changes in hydrogen,

[00:03:31] known as the Lyman-Alpha forest.

[00:03:33] Both of these help astronomers calculate how much hydrogen was transformed during reionization,

[00:03:39] and by extension, how much energy was needed to do that.

[00:03:43] Munez says astronomers know that all the hydrogen was neutral before reionization.

[00:03:47] And from there, you need enough extreme ultraviolet radiation to split each atom.

[00:03:53] So at the end of the day, you can do the math and figure out when reionization ended.

[00:03:58] But now, the James Webb Space Telescope is challenging this established model.

[00:04:03] With Webb, astronomers compare further back into the cosmos than ever before,

[00:04:08] and therefore deeper into this critical epoch.

[00:04:11] And this is leading to many unexpected observations in the early universe,

[00:04:15] one of which is an apparently greater abundance of extreme ultraviolet emitting galaxies

[00:04:20] than what was expected.

[00:04:22] Webb has revealed that these bright galaxies were enough to ionize the universe all by themselves,

[00:04:27] and this counters what was anticipated.

[00:04:30] And so with these new observations, all the accounting is off.

[00:04:34] Munez says if you were to trust the Webb results blindly,

[00:04:37] it tells you that reionization ended 550 million to 650 million years after the Big Bang,

[00:04:43] instead of the current estimates of a billion years.

[00:04:45] Now, if that's true, the cosmic microwave background radiation should look very different,

[00:04:50] and the Lyman-Alpha-Forus would also be different.

[00:04:53] So, there's the problem.

[00:04:55] It's unlikely that reionization happened hundreds of million years earlier than predicted.

[00:05:00] That means something else is going on, something we don't understand.

[00:05:03] It means that the established models are missing a key piece of crucial information.

[00:05:08] For example, sometimes ionized photons and electrons could come back together,

[00:05:13] reforming neutral hydrogen atoms.

[00:05:15] That's a process called recombination.

[00:05:17] Now, if that happened more often than current models assume,

[00:05:20] that could increase how much ultraviolet light was needed to ionize the entire universe.

[00:05:26] Munez says more detailed and deeper observations of galaxies are needed

[00:05:29] in order to gain a better understanding of the recombination process.

[00:05:33] He says resolving this tension on reionization will be a key step

[00:05:38] to finally understanding this pivotal period of the universe's evolution.

[00:05:43] This is space-time.

[00:05:45] Still to come, old data yielding new secrets as NASA's Da Vinci spacecraft

[00:05:50] is prepared for its mission to Venus.

[00:05:52] And China has successfully tested its first reusable satellite.

[00:05:57] All that and more still to come on space-time.

[00:06:15] Due to launch in the early 2030s, NASA's Da Vinci mission will investigate

[00:06:20] whether the planet Venus, a sweltering world wrapped in an atmosphere of noxious gases,

[00:06:25] once had oceans and continents like the Earth.

[00:06:28] Consisting of a flyby spacecraft and a descent probe,

[00:06:31] Da Vinci will focus on a mountainous ridge called Alpha Reggio,

[00:06:35] a possible ancient continent.

[00:06:36] Alpha Reggio is one of the most mysterious places on Venus.

[00:06:40] Its terrain, known as Tessera, is similar in appearance to rugged Earth mountains,

[00:06:45] but much more irregular and disorderly.

[00:06:47] So called because they resemble a geometric parquet floor pattern,

[00:06:51] Tessera have been found only on Venus.

[00:06:53] And Da Vinci will be the first mission to explore this terrain in detail

[00:06:57] and map its topography.

[00:06:58] Da Vinci's probe will begin photographing Alpha Reggio,

[00:07:02] collecting the highest resolution images yet,

[00:07:04] once it descends below the planet's clouds,

[00:07:06] starting at about 40 kilometres in altitude.

[00:07:08] So far, only a handful of mostly Soviet spacecraft have plunged through Venus's atmosphere.

[00:07:14] And most of those didn't survive for very long once they reached the ground,

[00:07:18] thanks to the planet's extreme surface temperatures of 162 degrees Celsius

[00:07:21] and its crushing atmospheric pressure,

[00:07:24] which is some 92 times greater than average sea level surface pressure on Earth.

[00:07:29] Venus is shrouded in thick opaque clouds,

[00:07:32] producing corrosive droplets of metal-eating sulphuric acid.

[00:07:35] Scientists have seen what look like snow caps on some of Venus's taller mountain ranges.

[00:07:39] But that snow isn't frozen water, it's actually metallic.

[00:07:43] In fact, the clouds are so heavy,

[00:07:45] they quite literally crush Venus's rich carbon dioxide-based atmosphere,

[00:07:49] acting like the lid of a pressure cooker and giving the planet its high surface pressure.

[00:07:53] The surface of Venus is dominated by more than 1600 volcanic structures.

[00:07:58] That's more than any other planet in the solar system.

[00:08:01] So, there's a lot to study, and scientists developing the new Da Vinci spacecraft

[00:08:05] are preparing for the mission by looking over all data we have from previous flights.

[00:08:10] And by using modern data analysis techniques to pour over decades-old observations,

[00:08:15] they've made some interesting new discoveries.

[00:08:18] Between 1990 and 1994, NASA's Magellan spacecraft used radar imaging and altimetry

[00:08:24] to map the topography of the Alpha Regia region from Venus orbit.

[00:08:28] Now, Da Vinci's team wanted more data,

[00:08:30] so they supplemented this information with radar images taken on three occasions

[00:08:34] from the former Arecibo Observatory in Puerto Rico.

[00:08:38] And they then used machine vision computer modelling to scrutinise the data

[00:08:41] and fill in gaps in the information.

[00:08:44] And this has provided amazing new tenfold higher-resolution images of Alpha Regia,

[00:08:49] including new geologic features which are raising fresh questions

[00:08:53] about how these patterns could have been formed.

[00:08:55] The same sort of evidence has already allowed scientists to find new evidence

[00:08:59] for modern-day volcanic activity on Venus.

[00:09:02] With three forthcoming missions to Venus,

[00:09:05] NASA's Da Vinci and Veritas,

[00:09:07] plus the European Space Agency's Envision mission,

[00:09:09] more and more archival space data is being used to help scientists prepare for their missions.

[00:09:14] One of the other problems facing Da Vinci scientists

[00:09:17] are the atmospheric gases which will scatter light in ways that make the images appear blurred.

[00:09:22] So Da Vinci scientists are working on a solution.

[00:09:25] Recently, scientists reanalyzed old Venus data imaging

[00:09:28] using a new artificial intelligence technique

[00:09:30] that can sharpen the images and use them to compute three-dimensional topographic maps.

[00:09:35] And this technique will ultimately help the team optimise Da Vinci's images and maps

[00:09:39] of the Alpha Regio mountains.

[00:09:41] The upgraded images will give scientists the most detailed view ever,

[00:09:45] right down to resolutions of a metre per pixel,

[00:09:48] possibly allowing them to detect small features such as rocks, rivers and gullies for the first time.

[00:09:53] By analyzing the surface texture and rock types at Alpha Regio,

[00:09:57] scientists hope to determine if Venci and Tesserae formed through the same processes

[00:10:01] that created mountains and some of the volcanoes here on Earth.

[00:10:05] This report from NASA TV.

[00:10:07] The surface of Venus is completely inhospitable for life.

[00:10:12] Barren, dry, crushed under an atmosphere about 90 times the pressure of Earth's,

[00:10:17] and roasted by temperatures two times hotter than an oven.

[00:10:21] But was it always that way?

[00:10:22] Could Venus once have been a twin of Earth?

[00:10:25] A habitable world with liquid water oceans?

[00:10:28] Here are 10 mysteries of Venus that NASA scientists are still grappling with.

[00:10:37] Did Venus ever host life?

[00:10:39] To answer this question, we first need to understand the past environment on Venus.

[00:10:44] This involves studying the atmosphere, geology and history of the planet,

[00:10:48] something NASA's Da Vinci mission plans on exploring in great detail.

[00:10:53] Why did Venus evolve so differently than Earth?

[00:10:55] Venus and Earth are similar in size and density, and yet they are strikingly different.

[00:11:00] Air pressure at the surface of Venus is 90 times that of Earth.

[00:11:04] Venus rotates on its axis backwards compared to the other planets in the solar system,

[00:11:09] and the surface of Venus is over 900 degrees Fahrenheit,

[00:11:12] making it the hottest planet in our solar system, hot enough to melt lead.

[00:11:17] Venus's evolution through time may help us understand how habitability evolves over time,

[00:11:23] and where we might find habitable planets beyond our solar system.

[00:11:27] How did Venus form?

[00:11:29] It is still not known if Venus was bombarded by comets and asteroids rich in water the way Earth was.

[00:11:36] Understanding the delivery of water to Venus is important for evaluating its potential to host oceans in the past.

[00:11:44] What is the atmosphere composition at Venus?

[00:11:47] One of the biggest mysteries of Venus's atmosphere lies in the lowermost or deep atmosphere,

[00:11:52] where carbon dioxide is heated and pressurized to the point where it acts more like a hot liquid than a gas.

[00:11:59] The da Vinci probe will measure chemistry, pressure, temperature and dynamics at least every 200 meters,

[00:12:06] as it descends through Venus's atmosphere to the surface.

[00:12:08] How are the rocks of Venus formed?

[00:12:13] Da Vinci's high-resolution imaging beneath the clouds will test ideas about the role of water in forming what may be ancient continental crust on Venus at human scales.

[00:12:24] Da Vinci will study one of these tesserae, Alpha Regio, to better understand its composition.

[00:12:29] How much water did Venus have?

[00:12:32] Liquid water is essential for life.

[00:12:34] We cannot assess Venus's past habitability without knowing how much water Venus may have had.

[00:12:40] And when and how it lost that water.

[00:12:42] Scientists will use measurements of the atmosphere from the da Vinci probe to explore clues of the story of past water on our sister planet.

[00:12:51] What is the nature of surface activity at Venus?

[00:12:54] Earth's crust hosts a network of relatively thin plates jostling around on the planet's surface in constant horizontal motion.

[00:13:02] If similar plate tectonics exist on Venus, the planet's crust must experience continental drift, like Earth.

[00:13:08] Another key mystery about the surface of Venus is volcanism.

[00:13:11] The two upcoming missions to Venus, da Vinci and Veritas, aim to understand the current volcanic activity at Venus.

[00:13:19] What do the mountains look like on Venus?

[00:13:22] Previous Venus landers, Venera and Vega, have taken photographs of the Venusian planes from the surface.

[00:13:28] But da Vinci's cameras will snap the first ever high-resolution aerial photos of a mountainous tesserae surface as the probe descends over the rugged Alpha Regio Highlands region.

[00:13:38] Are there Venus-like planets beyond our solar system?

[00:13:41] We will be able to relate what we discover at Venus to Venus-like exoplanets observed by the James Webb Space Telescope.

[00:13:49] If Venus shows signs of previous habitability, that could mean these exoplanets might be habitable as well.

[00:13:55] New mysteries we haven't thought of yet.

[00:13:57] There are many new mysteries we can't even imagine right now.

[00:14:00] With NASA's newest missions to our sister planet, there are plenty of new discoveries to be made.

[00:14:05] Venus, here we come.

[00:14:11] This is Space Time.

[00:14:13] Still to come, China tests its first reusable satellite.

[00:14:16] And later in the science report, paleontologists discover one of Earth's earliest life forms in the South Australian outback.

[00:14:23] All that and more still to come on Space Time.

[00:14:42] China has successfully tested its first reusable satellite.

[00:14:45] The Shaiwan-19 was launched from the Zhukhan Satellite Launch Center aboard a Long March 2D rocket.

[00:14:51] The US Space Force tracked the mission, claiming the satellite was placed into a 322 by 339 km high orbit, inclined at 41.6 degrees.

[00:15:02] The China National Space Administration says the satellite was recovered at the Dongfang landing site in Inner Mongolia 13 and a half days later.

[00:15:10] Beijing claims the mission carried a number of payloads, including plant seeds, microorganism samples, technology demonstration devices, space experimental instruments and cultural items.

[00:15:22] This is Space Time.

[00:15:24] And time now to take a brief look at some of the other stories making news in science this week with a science report.

[00:15:45] A new study has shown that people who sustain hearing loss in older age are more likely to go on to develop Parkinson's disease.

[00:15:52] The findings, reported in the Journal of the American Medical Association, suggest that this risk can be mitigated by tracking the hearing loss itself.

[00:16:00] The authors used data from an American veteran health study to compare hearing loss measured by audiograms with later diagnosis of Parkinson's disease.

[00:16:10] They found that the more severe hearing loss was in a person, the more likely they were to go on to develop Parkinson's.

[00:16:16] However, they say that if a person with hearing loss received a hearing aid within two years of their audiogram, the risk was reduced, suggesting effective management of hearing loss could mitigate Parkinson's risk.

[00:16:30] Paleontologists have discovered one of Earth's earliest life forms in the South Australian outback.

[00:16:35] The ancient fossil Quas de Zosimsonorium, which dates back some 550 million years, was found at the famous Ediacra National Park Reserve in the northern Flinders Ranges.

[00:16:46] This region has become famous for its early marine animal fossils, which represent some of the planet's first complex animal life, known as the Ediacran,

[00:16:55] a pivotal moment in the history of evolution during which single-celled organisms began to evolve into more complex life forms.

[00:17:02] The new findings reported in the journal Evolution and Development show this animal, which is a little smaller than the size of your palm,

[00:17:09] has a question mark shape in the middle of its body, which distinguishes between the left and the right.

[00:17:15] There are no other fossils from this time period which have shown this type of organisation.

[00:17:20] Now this is especially interesting, as it's also one of the first animals that was capable of moving on its own.

[00:17:26] The study's authors described the creature as behaving sort of like a small marine version of a Roomba vacuum cleaner,

[00:17:33] consuming nutrients from microscopic algae, bacteria and other organisms as it moved along the sea floor.

[00:17:39] The collection of microbes formed an organic mat, like a layer of slime filled with nutrients.

[00:17:45] This formed a specific texture preserved in the rock slabs which make up the park's fossil beds.

[00:17:51] Scientists discovered Quaze Teo impressions, along with evidence of its trails, known as trace fossils, in this fossilised matte texture.

[00:17:59] A new study warns that by the end of the century, up to 33% of frog and toad habitats could become arid,

[00:18:06] putting further pressure on an already threatened class of animals.

[00:18:09] The findings reported in the journal Nature Climate Change suggest that if global temperatures rise by 2 degrees,

[00:18:15] then around 6.6% of frog and toad habitats will become arid-like.

[00:18:20] But if temperatures rise by 4 degrees, the arid conditions will impact around 33.6% of the areas they live in.

[00:18:27] The authors also found an increase in the habitats exposed to worsening drought, especially Australia.

[00:18:32] They say the findings highlight the combined threats of warming and environmental drying, which frogs and toads are already facing.

[00:18:41] A new Gallup poll shows that support for childhood vaccinations has dropped considerably since 2019.

[00:18:48] The data shows that the percentage of Americans who say vaccinating their children is essential

[00:18:53] has dropped from 58% in 2019 down to just 40% now.

[00:18:58] The survey also suggests that only 51% believe the government should require children to be vaccinated.

[00:19:05] That's down from 62% in 2019.

[00:19:08] Meanwhile, a Centers for Disease Control report has found that vaccination rates have dropped from 95%

[00:19:13] amongst kindergarten kids during the 2019-2020 school year to 93% two years later.

[00:19:20] Tim Mendham from Australian Skeptic says,

[00:19:22] While 2% may not seem like much for diseases like measles, herd immunity becomes threatened when vaccination rates fall below 95%.

[00:19:31] Can you believe it that we almost wiped out measles?

[00:19:32] A number of years ago, the actual cases of measles were dropping dramatically.

[00:19:36] I think about eight years ago, it fell under 100,000 cases worldwide for the first time.

[00:19:41] And it was going down and down and down.

[00:19:42] And then suddenly the anti-vaccination movement got on top of it.

[00:19:46] See its famous anti-vaxxers who are putting forward supposed theories about the MMR vaccine,

[00:19:51] the measles, mump, rubella vaccine, etc.

[00:19:52] And that scared a lot of people.

[00:19:54] And as soon as it scares people, they stopped vaccinating their kids.

[00:19:57] And the cases of measles increased dramatically.

[00:19:59] I think a case in Oregon in the US, it's actually in the last year has increased 300% or close to it.

[00:20:06] So yeah, triple the number of measles cases.

[00:20:08] Now the numbers are not huge.

[00:20:09] A lot of people don't report them, although they should.

[00:20:11] The doctors should.

[00:20:11] It's a dangerous disease.

[00:20:13] It's not just a simple thing of sort of getting a few spots and that sort of stuff.

[00:20:16] It can kill, especially for kids.

[00:20:17] So we regard that as pretty serious.

[00:20:19] And it was very encouraging to see the number of cases dropping.

[00:20:22] And then suddenly anti-vaxxers come on the scene.

[00:20:24] They're sort of better at using the media than they used to be.

[00:20:27] And COVID scared a lot of people.

[00:20:28] So the rates of measles has jumped up again, especially in the US, but across the world.

[00:20:32] And it's not just measles.

[00:20:33] Polio rates are going up again, which is unheard of.

[00:20:36] That's right.

[00:20:36] Polio was almost entirely wiped.

[00:20:38] It was only in two countries, I think, at one stage fairly recently.

[00:20:41] Now it's coming back up again for much the same reason.

[00:20:44] So people don't like getting a polio vaccine.

[00:20:46] The issue is most people alive today have never seen a case of polio.

[00:20:49] They've never seen someone in a lying lung machine or walking around with calipers.

[00:20:53] Most of them have never seen a case of measles.

[00:20:55] But they're there and they're endemic.

[00:20:56] The moment you take a foot off the brake, they'll leap back up again.

[00:20:59] And that's what's happening.

[00:21:00] And of course, the ideal figure for vaccination, especially amongst kids, is about 95%.

[00:21:04] That's when you reach the stage of herd immunity, where the measles have fewer candidates to actually attack

[00:21:09] and therefore have less spreading capacity.

[00:21:11] But in some cases, the vaccination rate of adults and things is down below 50%.

[00:21:16] And that is ripe for these diseases to attack the population.

[00:21:20] And once they start, they grow and they grow and they grow and they start killing people.

[00:21:24] Well, you mentioned Oregon earlier.

[00:21:25] Yeah.

[00:21:25] That's a bit of a hippie zone.

[00:21:26] Of course, we have our own version of Oregon here in Australia, the Northern Rivers of New South Wales.

[00:21:31] That's right.

[00:21:32] The north coast of New South Wales is a strong area for alternative lifestyle people.

[00:21:36] And a lot of alternative lifestyle people think vaccines are, one, unnecessary, two, dangerous,

[00:21:42] three, a government conspiracy to try and take over your minds or whatever,

[00:21:46] to inject mind-altering silicon chips into your bloodstream.

[00:21:49] And all sorts of theories like that.

[00:21:51] And therefore, the vaccination rate's there rather than 90-odd percent.

[00:21:54] Amongst kids are down to 60%.

[00:21:55] And there are cases of whooping cough where the vaccine is not as effective as a lot of the other ones are,

[00:22:01] but it's still effective.

[00:22:02] And whooping cough is definitely not good for little kids, babies especially, who can't be vaccinated.

[00:22:07] They're too young.

[00:22:08] But because the adults are not vaccinated, the mothers are vaccinated before giving birth.

[00:22:12] That kills kids.

[00:22:13] That's Tim Mindum from Australian Skeptics.

[00:22:31] And that's the show for now.

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