Category: 7. Science

Earth formed about 4.6 billion years ago, during the geological eon known as the Hadean. The name “Hadean” comes from the Greek god of the underworld, reflecting the extreme heat that likely characterized the planet at the time.

By 4.35 billion years ago, the Earth might have cooled down enough for the first crust to form and life to emerge.

However, very little is known about this early chapter in Earth’s history, as rocks and minerals from that time are extremely rare. This lack of preserved geological records makes it difficult to reconstruct what the Earth looked like during the Hadean Eon, leaving many questions about its earliest evolution unanswered.

We are part of a research team that has confirmed the oldest known rocks on Earth are located in northern Québec. Dating back more than four billion years, these rocks provide a rare and invaluable glimpse into the origins of our planet.

Remains from the Hadean Eon

The Hadean Eon is the first period in the geological timescale, spanning from Earth’s formation 4.6 billion years ago and ending around 4.03 billion years ago.

The oldest terrestrial materials ever dated by scientists are extremely rare zircon minerals that were discovered in western Australia. These zircons were formed as early as 4.4 billion years ago, and while their host rock eroded away, the durability of zircons allowed them to be preserved for a long time.

Studies of these zircon minerals has given us clues about the Hadean environment, and the formation and evolution of Earth’s oldest crust. The zircons’ chemistry suggests that they formed in magmas produced by the melting of sediments deposited at the bottom of an ancient ocean. This suggests that the zircons are evidence that the Hadean Eon cooled rapidly, and liquid water oceans were formed early on.

Other research on the Hadean zircons suggests that the Earth’s earliest crust was mafic (rich in magnesium and iron). Until recently, however, the existence of that crust remained to be confirmed.

In 2008, a study led by one of us — associate professor Jonathan O’Neil (then a McGill University doctoral student) — proposed that rocks of this ancient crust had been preserved in northern Québec and were the only known vestige of the Hadean.

Since then, the age of those rocks — found in the Nuvvuagittuq Greenstone Belt — has been controversial and the subject of ongoing scientific debate.

‘Big, old solid rock’

The Nuvvuagittuq Greenstone Belt is located in the northernmost region of Québec, in the Nunavik region above the 55th parallel. Most of the rocks there are metamorphosed volcanic rocks, rich in magnesium and iron. The most common rocks in the belt are called the Ujaraaluk rocks, meaning “big old solid rock” in Inuktitut.

The age of 4.3 billion years was proposed after variations in neodymium-142 were detected, an isotope produced exclusively during the Hadean through the radioactive decay of samarium-146. The relationship between samarium and neodymium isotope abundances had been previously used to date meteorites and lunar rocks, but before 2008 had never been applied to Earth rocks.

This interpretation, however, was challenged by several research groups, some of whom studied zircons within the belt and proposed a younger age of at most 3.78 billion years, placing the rocks in the Archean Eon instead.

Confirming the Hadean Age

In the summer of 2017, we returned to the Nuvvuagittuq belt to take a closer look at the ancient rocks. This time, we collected intrusive rocks — called metagabbros — that cut across the Ujaraaluk rock formation, hoping to obtain independent age constraints. The fact that these newly studied metagabbros are in intrusion in the Ujaraaluk rocks implies that the latter must be older.

The project was led by masters student Chris Sole at the University of Ottawa, who joined us in the field. Back in the laboratory, we collaborated with French geochronologist Jean-Louis Paquette. Additionally, two undergraduate students — David Benn (University of Ottawa) and Joeli Plakholm (Carleton University) participated to the project.

We combined our field observations with petrology, geochemistry, geochronology and applied two independent samarium-neodymium age dating methods, dating techniques used to assess the absolute ages of magmatic rocks, before they became metamorphic rocks. Both assessments yielded the same result: the intrusive rocks are 4.16 billion years old.

The oldest rocks

Since these metagabbros cut across the Ujaraaluk formation, the Ujaraaluk rocks must be even older, placing them firmly in the Hadean Eon.

Studying the Nuvvuagittuq rocks, the only preserved rocks from the Hadean, provides a unique opportunity to learn about the earliest history of our planet. They can help us understand how the first continents formed, and how and when Earth’s environment evolved to become habitable.

A new brain imaging study published in Current Biology has uncovered surprising neural activity in people with aphantasia—a condition where individuals report being unable to form mental images. Although they describe a complete absence of visual imagery, their brains still show patterns of activity in the early visual cortex when they attempt to imagine visual stimuli. However, this activity differs in important ways from what’s seen in people who do experience vivid mental imagery, offering insight into how consciousness might be linked to sensory representations in the brain.

Aphantasia is a relatively newly defined condition in which people are unable to form mental images voluntarily. While those with aphantasia can describe objects and scenes using words or concepts, they report no visual “pictures” in the mind’s eye. Since much of what is known about mental imagery comes from people who can generate vivid images, the researchers wanted to know what happens in the brain when someone with aphantasia tries to visualize something. Do they engage the same brain regions, or are there deeper differences in how their brains represent imagined information?

To answer these questions, the research team compared people with aphantasia to individuals with typical visual imagery using functional magnetic resonance imaging (fMRI). The goal was to examine how both groups activated early visual brain regions—especially the primary visual cortex—during attempts to visualize simple stimuli. The researchers focused on whether the brain could still represent specific content in people who lack a subjective visual experience.

The study involved 14 participants with verified aphantasia and 18 control participants with typical imagery. All were right-handed and had normal or corrected vision. Participants completed the Vividness of Visual Imagery Questionnaire to assess their subjective imagery, and their imagery ability was further validated using an objective task called the binocular rivalry paradigm. This method measures how imagining a visual pattern affects what people perceive shortly afterward. As expected, those with aphantasia scored near the floor on the vividness questionnaire and showed little or no sensory bias in the binocular rivalry task, confirming that they lacked typical imagery experience.

In the main experiment, the researchers used fMRI to measure brain activity while participants either viewed or attempted to imagine simple visual patterns—specifically colored Gabor patches—at specific locations on a screen. Each participant completed several types of scans: imagery generation, passive viewing, retinotopic mapping to define visual areas, and region-of-interest localization to pinpoint the parts of the brain involved in processing the stimuli. During the imagery task, participants received a visual cue indicating which pattern to imagine and where to place it in the visual field. After each attempt, they rated how vivid their imagery had felt.

Although people with aphantasia gave extremely low vividness ratings—averaging around 1 on a 1-to-4 scale—their brain activity told a more complex story. In both groups, fMRI signals from early visual areas could be used to decode what kind of pattern a person was trying to imagine. In other words, the brain still encoded specific information about the content of the imagery—even in the absence of subjective experience.

But there were clear differences in how that information was represented. In people with typical imagery, activity in the visual cortex showed expected patterns: stronger responses in the hemisphere opposite to the side of the visual field where the stimulus was imagined. In contrast, people with aphantasia showed the reverse: stronger responses in the same-side hemisphere (ipsilateral) instead of the opposite (contralateral). This suggests a different functional organization of visual activity during imagery attempts.

While the imagery content could be decoded in both groups, only in the control group did the patterns of brain activity overlap between imagery and actual perception. In the control group, algorithms trained on imagery-related brain data could accurately identify visual stimuli seen during passive viewing—and vice versa. This kind of cross-decoding failed in the aphantasia group. Their visual cortex did encode information about imagery attempts, but those patterns did not match those generated during real visual perception.

This mismatch might explain why people with aphantasia experience no visual imagery even though their brains generate structured representations during imagery tasks. According to the researchers, the results point to a difference not just in the strength of visual signals, but in their format. The activity in the visual cortex of people with aphantasia appears to be “less sensory,” meaning it may lack the specific qualities that give rise to conscious visual experience.

The researchers also looked at broader brain networks. During imagery attempts, people with aphantasia showed stronger activity in brain regions associated with language and auditory processing, such as the superior temporal gyri. They also had weaker functional connections between these regions and visual areas. This could indicate that when people with aphantasia try to visualize, they may rely more on verbal or conceptual strategies rather than generating vivid internal images.

To test whether differences in attention or effort might explain the results, the researchers ran a follow-up study with control participants. These individuals were asked to imagine either a clear or blurry version of the same visual patterns. Their reported effort levels and brain activation were similar across both conditions, suggesting that differences in subjective clarity do not necessarily reflect differences in cognitive effort. This makes it less likely that the patterns seen in aphantasia are simply due to lower motivation or task engagement.

Although the findings shed new light on the neural basis of aphantasia, the authors note several limitations. The sample size was relatively small, especially given the rarity of aphantasia, and most participants in both groups were women. Also, while the study focused on low-level visual features, it did not examine whether similar results would hold for more complex images, such as faces or scenes. The absence of eye-tracking during scanning means researchers could not fully rule out whether subtle eye movements influenced the neural signals.

But the results still offer evidence that people with aphantasia can generate structured, content-specific activity in the visual cortex, even though they lack a conscious image. This dissociation between brain activity and experience challenges long-held assumptions that activity in early visual areas is directly tied to visual awareness. Instead, it suggests that not all neural representations are created equal—some may carry enough sensory information to generate conscious images, while others may not.

The study opens new avenues for understanding the neural basis of mental imagery and visual consciousness. Future research could explore what kinds of information are encoded in the brain during imagery attempts in aphantasia, and whether different feedback connections in the brain might account for the altered representations.

The study, “Imageless imagery in aphantasia revealed by early visual cortex decoding,” was authored by Shuai Chang, Xinyu Zhang, Yangjianyi Cao, Joel Pearson, and Ming Meng.

The Neanderthals are our closest extinct relatives, and they continue to fascinate as we peer back through tens of thousands of years of history.

In a new discovery about this mysterious yet often familiar species, researchers have found ancient evidence of a Neanderthal “fat factory” in what is now Germany.

Operational around 125,000 years ago, the factory would’ve been a place where Neanderthals broke and crushed the bones of large mammals to extract valuable bone marrow and grease, used as a valuable extra food source.

Related: Neanderthal DNA Exists in Humans, But One Piece Is Mysteriously Missing

According to scientists, this is the earliest evidence yet for this type of sophisticated, large-scale bone processing, including both bone marrow and grease: the first confirmation Neanderthals were also doing this some 100,000 years before our species made it to Europe.

“This was intensive, organised, and strategic,” says archaeologist Lutz Kindler from the MONREPOS Archaeological Research Center in Germany.

“Neanderthals were clearly managing resources with precision – planning hunts, transporting carcasses, and rendering fat in a task-specific area. They understood both the nutritional value of fat and how to access it efficiently – most likely involving caching carcass parts at places in the landscape for later transport to and use at the grease rendering site.”

The researchers found their evidence on a site called Neumark-Nord in eastern Germany, not far from the city of Halle. They uncovered more than 100,000 bone fragments from what are thought to be at least 172 large mammals, including horses and deer.

A good proportion of the bones showed cut marks and signs of intentional breakage, pointing to deliberate butchering – these weren’t just leftovers from a hunt. There were also indications of tool use and fires in the same location, all in a relatively small area.

Add all of that together, and it seems clear that some kind of systematic, organized bone processing was going on here. Similar processes have been linked to Neanderthal sites before, but not at this level of scale or sophistication.

“Bone grease production requires a certain volume of bones to make this labour-intensive processing worthwhile and hence the more bones assembled, the more profitable it becomes,” says archaeologist Sabine Gaudzinski-Windheuser from MONREPOS.

We can add this to the long list of studies that have revealed Neanderthals were much smarter than they’re often made out to be. Thanks to recent research we know they were adept swimmers, capable brewers, and abstract thinkers – who raised their kids and used speech patterns in a similar way to humans.

Ultimately though, Homo sapiens thrived and survived, while Neanderthals died out. That’s another story that archaeologists are busy investigating the whys and wherefores of, but all we have of the Neanderthals now are the remains and the sites they left behind – which will no doubt give up more revelations in the future.

“The sheer size and extraordinary preservation of the Neumark-Nord site complex gives us a unique chance to study how Neanderthals impacted their environment, both animal and plant life,” says computer scientist Fulco Scherjon from MONREPOS.

“That’s incredibly rare for a site this old – and it opens exciting new possibilities for future research.”

The research has been published in Science Advances.

• We are reliant on satellite services for modern life. We use them for communication, banking, navigation and so much more.
• In order to use satellites, we need to know exactly where they are. And that also depends on where Earth and the sun are, too.
• So astronomers use radio waves from distant black holes to help pinpoint our place in the universe. But the radio spectrum is getting crowded.

By Lucia McCallum, University of Tasmania. Edits by EarthSky.

Phones and wifi block our view of our place in the universe

The scientists who precisely measure the position of Earth are in a bit of trouble. We’re talking about geodesy, the science of accurately measuring and understanding the Earth’s geometric shape, orientation in space, and gravity field. These scientists’ measurements are essential for the satellites we use for navigation, communication and Earth observation every day.

But you might be surprised to learn that making geodetic measurements depends on tracking the locations of black holes in distant galaxies.

The problem is, the scientists need to use specific frequency lanes on the radio spectrum highway – where the available radio frequency spectrum is pictured as being divided into “lanes” or smaller bands, similar to lanes on a road – to track those black holes.

And with the rise of wifi, mobile phones and satellite internet, travel on that highway is starting to look like a traffic jam.

Why we need black holes

Satellites and the services they provide have become essential for modern life. From precision navigation in our pockets to measuring climate change, running global supply chains and making power grids and online banking possible, our civilization cannot function without its orbiting companions.

To use satellites, we need to know exactly where they are at any given time. Precise satellite positioning relies on the so-called global geodesy supply chain.

This supply chain starts by establishing a reliable reference frame as a basis for all other measurements. Satellites are constantly moving around Earth, Earth is constantly moving around the sun, and the sun is constantly moving through the galaxy. So this reference frame needs careful calibration via some relatively fixed external objects.

As it turns out, the best anchor points for the system are the black holes at the hearts of distant galaxies. Black holes spew out streams of radiation as they devour stars and gas.

And these black holes are the most distant and stable objects we know. Using a technique called very long baseline interferometry, we can use a network of radio telescopes to lock onto the black hole signals and disentangle Earth’s own rotation and wobble in space from the satellites’ movement.

Different lanes on the radio highway

We use radio telescopes because we want to detect the radio waves coming from the black holes. Radio waves pass cleanly through the atmosphere. And we can receive them during day and night and in all weather conditions.

But we also use radio waves for communication on Earth. This includes things such as wifi and mobile phones. There is close regulation on the use of different radio frequencies, or different lanes on the radio highway. And a few narrow lanes are reserved for radio astronomy.

However, in previous decades the radio highway had relatively little traffic. Scientists commonly strayed from the radio astronomy lanes to receive the black hole signals.

To reach the very high precision needed for modern technology, geodesy today relies on more than just the lanes exclusively reserved for astronomy.

Radio traffic on the rise

In recent years, human-made electromagnetic pollution has vastly increased. When wifi and mobile phone services emerged, scientists reacted by moving to higher frequencies.

However, they are running out of lanes. Six generations of mobile phone services (each occupying a new lane) are crowding the spectrum. Not to mention, a fleet of thousands of satellites directly send internet connections.

Today, the multitude of signals are often too strong for geodetic observatories to see through them to the very weak signals that black holes emit. This puts many satellite services at risk.

How to help find our place in the universe

To keep working into the future – to maintain the services on which we all depend – geodesy needs some more lanes on the radio highway. When international treaties at world radio conferences divide up the spectrum, geodesists need a seat at the table.

Other potential fixes might include radio quiet zones around our essential radio telescopes. Work is also underway with satellite providers to avoid pointing radio emissions directly at radio telescopes.

Any solution has to be global. For our geodetic measurements, we link radio telescopes together from all over the world, allowing us to mimic a telescope the size of Earth. Each nation individually primarily regulates the radio spectrum, making this a huge challenge.

But perhaps the first step is increasing awareness. If we want satellite navigation to work, our supermarkets to be stocked and our online money transfers arriving safely, we need to make sure we have a clear view of those black holes in distant galaxies. And that means clearing up the radio highway.

Lucia McCallum, Senior Scientist in Geodesy, University of Tasmania

We republished this article from The Conversation under a Creative Commons license. Read the original article.

Bottom line: Astronomers help us locate our place in the universe by analyzing the radio waves that come from black holes in the distant universe. But the radio spectrum is getting crowded with our everyday technology.

The first full moon of astronomical summer in the Northern Hemisphere is about to rise. Known as the Buck Moon, it will turn full Thursday, July 10 and will be one of the lowest-hanging full moons of the year.

Although the moon officially reaches its full phase at 4:38 p.m. EDT on June 10, that moment occurs while the moon is still below the horizon for viewers in North America. The best time to see the full Buck Moon will be at moonrise, at dusk, on Thursday evening, when the moon will appear on the eastern horizon as an orange orb. Use a moon calculator to determine the exact time you should look for the moon from your location.

Care and Feeding is Slate’s parenting advice column. Have a question for Care and Feeding? Submit it here.

Dear Care and Feeding,

My husband, “Wade,” and I are Chinese-American. My family has been in the U.S. for generations, while he is the first of his family to be born here. Wade and I have two daughters, ages 2 and 4, whom we adore. The problem is my very traditional in-laws, who are applying pressure to us to try again to have a son. Wade thinks we should just grey rock their attempts to convince us to have another child for the sake of carrying on the family legacy—i.e., let them waste their breath. But I worry about our girls as they get older and are better able to understand the meaning behind their grandparents’ constant harping on this. I fear they’ll think their grandparents love them less than they would if they were boys; I don’t want them to feel inferior because of their gender. What’s a good way of dealing with this without offending my in-laws?

—The Old Beliefs Should Have Stayed in the Old World

Dear Beliefs.

I’ll admit, if I were you, I would be honest with them—I think you can do that without offending them. You and your husband might tell them that you’re very happy with your two children and have no plans for a third. You can do this without getting in the weeds about sons versus daughters (and if they say—and they will say!—“But you don’t have a son! You must have a son!”, my advice would be to repeat what you’ve just said, and to do so as many times as necessary, without engaging with what they see as the “real” issue). You are not going to change them, and only they can decide to leave “the old beliefs” behind: You can’t make them. I would further urge you to speak frankly with them about your concern that if they continue to talk about this in the presence of your daughters, it will hurt them and harm their relationship with them. Tell your in-laws they are not to bring this up when their grandchildren are present—period. Tell them you do not wish for your children, who love and value their grandparents, to come to believe that their grandparents don’t love and value them.

If you and your husband cannot bring yourselves to tell his parents that you have no desire to have another child—even without breaking the news that you couldn’t care less about providing the son they so desperately want you to have—I’m not against your husband’s plan of letting them waste their breath and paying them no nevermind. But even if you go that route, somehow managing to spend the next 10 to 20 years making noncommittal noises or changing the subject every time they bring up the importance of your bringing a boy into the world, that doesn’t mean you shouldn’t speak up about the well-being of your (actual) children. You must still tell them how important it is to you that they not speak of this in your daughters’ presence, and explain why. If they continue to do it anyway, gather your daughters and leave the room. (When you’re next alone with their grandparents, repeat yourself again: This is not acceptable. This may inspire them to tell you, yet again, how crucial it is that you provide them a grandson. If you are determined to keep this charade going, you might say, “Yes, I know, but I must tell you that the repetition of your deep desire for one is not going to make him come along any faster.”)

And more important than any of this: Make sure your daughters know that they are loved and valued, that you and their father treasure them exactly as they are.

Dear Care and Feeding,

My son “Oliver” is 2 ½ years old and going through potty training. We got him some books on the subject and have shown him some videos to help encourage him. The problem is that he has become fixated on the topic. Now everything is about where pee and poop come from, where it’s supposed to go, how it’s something every living creature does, etc. He will initiate these conversations with perfect strangers when we are out; last week, we were at a restaurant when my husband needed to take him to the men’s room. Oliver came running back excitedly to the table and shouted, “I went pee-pee in the potty!” in front of everyone. I realize this is a phase, but I find it terribly embarrassing. Is there any way I can teach him discretion without inhibiting his progress?

—Pooped by All the Poop Talk

Dear Poop Talk,

I’m sorry to have to be the one to tell you this, but you’re going to have to get over this. You have a toddler! He’s excited about pee and poop and fascinated by everything he’s learned about it (and the whole process of food-to-waste-product really is kind of amazing, if you think about it, no? Oh, right, I forgot: You do not want to think about it). When kids are excited and fascinated by a subject, they want to talk about it. To everyone. Just you wait until he gets to the all-dinosaurs-all-the-time phase.

I say let him. It’s your embarrassment you need to get to work on—or, rather, your dread of being embarrassed. What’s so awful about a little embarrassment? (Or, an even better question: What is it exactly that there is to be so embarrassed about?) The appropriate response to his proud announcement was, “Well done! Good job!”, not, “Shhh!” And if he poop-chats up a stranger in the grocery store, and that stranger seems taken aback/distressed instead of amused or even just politely tolerant (recognizing that the person trying earnestly to engage them in a discussion of excrement’s amazing journey isn’t even 3 years old), you can always say, “Ah, well, potty training!” as you sail past. If a toddler uses hate speech (picked up somewhere, just repeating it as children do), that’s one thing: It’s never too soon to teach a child not to be hateful, racist, bigoted, or cruel. But teaching a toddler to be discreet is not only a losing battle, it’s also an effective way of teaching him that his exuberance is something for him to be ashamed of.

Catch Up on Care and Feeding

· Missed earlier columns this week? Read them here.
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Dear Care and Feeding,

I am a married man of many years. In my youth, I had a number of hot rods and have always been a car guy. I had a successful career and now have a net worth of $2 million, and the only debt we have is a small mortgage. There is a particular sports car I would like to purchase that is not expensive. My wife objects—she thinks I would look like an idiot driving this car at my age. All I want to do with it is take it to local car shows and cars-and-coffee meetups—that sort of thing. Is it all right for me to buy it anyway?

—Or Is She Right?

Dear Or Is She,

Does it matter if she’s right or wrong? The question is whether you care if you look like an “idiot,” in your wife’s words. (I’m not weighing in—I have no opinion on this matter. I don’t care enough about cars—or even know enough about cars—to make a judgment about the person driving one.)

If you want this sports car and you can afford it, and it will give you pleasure and do no harm to anyone, it’s time to search your soul: If you fear you might look foolish in your new hot rod, and the thought of that is painful enough to diminish the pleasure you imagine owning it will bring you, then don’t take that chance. If you consider the possibility of being judged harshly—old man in a hot car, ha ha, poor fool—and it horrifies you, as I suppose it horrifies your wife, then you should probably stick to the sedan or SUV you usually drive. But if you don’t care what people think (and why should you?), go ahead and tell your wife that. And tell her she doesn’t have to (ever) sit in the passenger seat, to spare her what I assume is her fear of being looked at as the pathetic old fool’s poor, clueless wife.

—Michelle

More Advice From Slate

I am mom to a 7-month-old. We live in a pretty conservative area, and I work in a male-dominated industry. In fact, all of my co-workers are men who have or had stay-at-home wives. When I was pregnant, several of my co-workers did not expect me to come back to work. Though I told them we planned on using day care, I guess they assumed some maternal instinct would come over me and I’d quit. They said terrible things to me.

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How did life on Earth begin? People have been asking that for ages. The answers remain scattered across rocks, oceans, and ancient landscapes. One clue hides in an essential ingredient for life – phosphorus.

Phosphorus is everywhere in living things. It holds together DNA and RNA. It forms the framework of cell membranes. No life can grow or function without it.

Yet, phosphorus mostly stays trapped in rocks. It hides inside phosphate minerals, which barely dissolve in water. That raises an old and puzzling question: how did early Earth get enough phosphorus to spark life?

Yuya Tsukamoto and Takeshi Kakegawa from Tohoku University took that question seriously. They decided to look where most people wouldn’t – deep under the sea, in rocks that are billions of years old.

Key element for life on Earth

The researchers focused on the Pilbara Craton in Western Australia, which holds some of the oldest known seafloor rocks.

The rocks are an astonishing 3.455 billion years old. The team’s discovery wasn’t subtle. It jumped out from the data.

“We analyzed 3.455-billion-year-old basaltic seafloor rocks in drill core samples recovered from the Pilbara Craton, Western Australia, discovering that P was significantly leached from the hydrothermally altered rocks compared to the least altered rocks,” explained Tsukamoto.

He noted that further mineralogical analyses indicated that phosphate minerals had undergone dissolution in rocks where P was depleted.

Simply put, hot fluids moved through these rocks and pulled phosphorus out. That phosphorus didn’t just disappear. It entered the surrounding seawater, turning parts of the ocean into phosphorus-rich zones.

Tracking the source of phosphorus

The rocks alone didn’t tell the whole story. The team wanted to understand what made this phosphorus release possible. They uncovered two kinds of hydrothermal fluids that shaped this process.

One type was hot, rich in sulfur, and capable of breaking down minerals quickly. The other was more surprising – mildly acidic to alkaline fluids at lower temperatures.

These fluids were common in the Archean era because Earth’s atmosphere back then was filled with carbon dioxide. That unique atmosphere made these fluids react in unexpected ways with the rocks.

The result? Massive amounts of dissolved phosphate in the water. The numbers were shocking. These fluids could carry up to 2 millimolar phosphate – nearly 1,000 times higher than what’s found in modern seawater.

Suddenly, early Earth wasn’t a barren place. Its oceans were filled with phosphorus.

Earth’s oceans held elements for life

This wasn’t just a chemistry experiment. The results changed how scientists think about early Earth. The researchers calculated how much phosphorus these underwater systems could release.

The findings were stunning. The amount of phosphorus released into the oceans by these hydrothermal systems could match, or even exceed, the amount entering modern oceans through rivers and weathering of land rocks.

“Importantly, this study provides direct evidence that submarine hydrothermal activity leached P from seafloor basaltic rocks and quantifies the potential P flux from these hydrothermal systems to the early ocean,” adds Tsukamoto.

Imagine ancient oceans filled with nutrients. These phosphorus-rich waters may have supported some of Earth’s earliest microbial life.

The ancient communities didn’t need a vast, lush planet. It only needed these hidden underwater environments to get started.

Hot springs and hidden worlds on land

The study also pointed to something beyond the oceans – hot springs on land. Hydrothermal systems aren’t just found under the sea. They exist on land too, in places like hot springs.

These environments might have also released phosphorus on early Earth. That means life’s building blocks weren’t limited to deep-sea vents. They could have existed in steaming pools on land.

This opens the door for more discoveries. Scientists now plan to study how phosphate behaves in rocks across different periods of Earth’s history. By tracing phosphorus through time, they hope to unlock new chapters of Earth’s story.

The message is clear: Life’s ingredients may have come from places on Earth we’ve only just begun to explore. Deep beneath the waves, within rocks touched by ancient fluids, the story of life may have quietly begun.

The study is published in the journal Geochimica et Cosmochimica Acta.

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Proxima Centauri b is the closest known exoplanet that could be in the habitable zone of its star. Therefore, it has garnered a lot of attention, including several missions designed to visit it and send back information. Unfortunately, due to technological constraints and the gigantic distances involved, most of those missions only weigh a few grams and require massive solar scales or pushing lasers to get anywhere near their target. But why let modern technological levels limit your imagination when there are so many other options, if still theoretical, options to send a larger mission to our nearest potentially habitable neighbor? That was the thought behind the Master’s Thesis of Amelie Lutz at Virginia Tech – she looked at the possibility of using fusion propulsion systems to send a few hundred kilogram probe to the system, and potentially even orbit it.

Since Proxima Centauri b is potentially habitable, there are a lot of different sensors that scientists would like to take to it to monitor it closely. Ms. Lutz details 11 sensors that would go on the craft, including spectrometers, magnetometers, and imaging and sounding systems that would allow it to peer beneath the planet’s ice sheets (if there are any).

In addition, there would be a high power communications array. However, getting a signal back from another star is difficult to say the least. Ms. Lutz proposes using the solar gravitational lens of Proxima Centauri itself to pump up the communication power and bandwidth to a respectable 10 Mb per second per watt of power devoted to the communications array.

Fraser discusses how fusion rockets could take us to other stars.

Where that power comes from is the real crux of the thesis though – the spacecraft would rely on a fusion generator both for its propulsion and for its electrical power. Ms. Lutz looked at three different types of fusion drives, each of which could use four different types of fuel.

First is a fusion driven rocket, which directly converts the energy created by the fusion reaction into thrust using a technique called magneto-inertial fusion. Next up is a inertial-electrostatic confinement engine, which is small and lightweight but suffers from technical challenges that limit its potential power output. Another potential drive system is an Antimatter Initiated Microfusion (AIM) system, which is the smallest system, but requires antimatter to get started, which is extraordinarily rare and expensive.

The four different types of fuels are those typically considered when discussing fusion reactions, either for commercial power generation or spacecraft propulsion. Deuterium-Deuterium (D-D) reactions are the simplest, but suffer from low energy output. Deuterium-Tritium (D-T) has a higher energy, but creates lots of neutrons that could potentially rip through a spacecraft’s shielding and destroy its internal systems. Proton-Boron-11 (p-B11) is more exotic, and made up of common materials, but requires really high temperatures for really low energy output. That leaves Deuterium-Helium-3 (D-He3).

Isaac Arthur discusses the potential of using fusion to drive our spaceships.

D-He3 has been the dream of many fusion experts for a long time. It has a high energy output, a low neutron output, and doesn’t require absurd temperatures to function. However, it has the drawback of the relative scarcity of He3 on Earth, though, as Ms. Lutz points out, there has been plenty of thought into how we could potentially mine it from the Moon.

To determine which combination of fuel and propulsion system is the best, Ms. Lutz considers several different mission profiles. First would be a non-decelerated fly-by – which would have the spacecraft zipping by its target planet at 24,000 km/s. That would not give very much time to do much, if any, actual science. An alternative would be to do a “slow” flyby, where the spacecraft decelerates on the latter half of its journey and passes by the planet going a more reasonable 25 km/s. Still fast, but enough that the science instruments could actually do some work.

However, with only a little bit more trajectory manipulation, Ms Lutz believes the spacecraft could enter a bounded orbit with Proxima Centauri b, allowing for multiple fly-bys and a significant amount of data collection. But to do so, it would require a combination of high energy output, low mass, and minimal neutrons.

The winning solution, according to her thesis, is a fusion driven rocket (FDR) configuration using D-He3 as a fuel source. By her calculations, such a system could arrive in the Proxima Centauri system and begin orbiting its target planet in around 57 years, not too bad for an interstellar mission of a 500 kg spacecraft. But, that being said, this whole study is all very theoretical, at least for now. We haven’t yet successfully tested any fusion drive concepts discussed in the paper, and even getting such a system into orbit would require significant technical and political effort. It will be a long while before any such system would be fitting onto an interstellar spacecraft, but it just might happen during Ms. Lutz’s career.

Learn More:
A. Lutz – Interstellar Mission Design of a Fusion-Powered Spacecraft to Proxima b

UT – Fusion-Enabled Comprehensive Exploration of the Heliosphere

UT – Magnetic Fusion Plasma Engines Could Carry us Across the Solar System and Into Interstellar Space

UT – Earth To Mars In 100 Days? The Power Of Nuclear Rockets