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Exoplanets have been discovered with a wide range of environmental conditions. WASP-76b is one of the most extreme with a dayside temperature of over 2,000 degrees. A team of researchers have found that it’s even more bizarre than first thought! It’s tidally locked to its host star so intense winds encircle the planet. They contain high quantities of iron atoms that stream from the lower to upper layers around the atmosphere.

Exoplanets exist outside of our Solar System and orbit other stars. The first confirmed discovery was back in the 1990’s and since then, over 5,200 have been discovered. Many of them are gas giants like Jupiter or Saturn and others are small rocky Earth like planets, minus perhaps their habitability status. As more advanced telescopes and detection techniques are developed not only will our detection levels increase further but so will our ability to explore these alien worlds. 

Artist impression of glory on exoplanet WASP-76b. Credit: ESA

One such exoplanet, WASP-76b has received quite a lot of attention of late. It is an ultra-hot gas giant that is 640 light years from us in the direction of the constellation Pisces. It was discovered back in 2013 and has an orbit that is very close to its host star, completing one orbit in just 1.8 Earth days! It’s the proximity to the star that has led to the extreme daytime temperatures of over 2,000 degrees. The intense heat is thought to vaporise iron which then condenses into liquid on the cooler night-time side and fall as iron rain! 

A team of astronomers, with some from the University of Geneva, announced their findings in the journal Astronomy & Astrophysics of evidence for intense iron winds in the atmosphere of WASP-76b. Astronomers have been focussing on this planet since its discovery to try and understand the mechanisms in the atmosphere of this ultra-hot Jupiter world. It really is a fascinating world and even a rainbow was detected there last April! 

The team kept their attention on the day-time side where the temperatures are far higher. They used the ESPRESSO spectrograph that was installed on the European Southern Observatory’s Very Large Telescope (yes that’s its name!) It is known for its stability and high spectral resolution so it can discern wonderfully fine levels of detail in a stellar spectrum. 

The four 8.2-metre Unit Telescopes of the Very Large Telescope at the Paranal Observatory complex. ESO/VLT

Using a technique known as high resolution emission spectroscopy, the team studied the visible light spectrum. The approach relies upon the detection of emission lines in a spectrum and enables the chemical composition to be decoded. Here they detected the chemical signature of iron and found that they were moving from lower levels to the higher layers of the atmosphere.

The study of exoplanet atmospheres help us to further develop our understanding of the range of environments on these alien worlds. As a gas giant, the discoveries on WASP-76b help us learn a little more about the climates of worlds that are barraged by extreme levels of radiation from their host star.

Source : Iron winds on an ultra-hot exoplanet

The post Iron Winds are Blowing on WASP-76 b appeared first on Universe Today.

A camera trap at an Australian nature refuge has captured a boisterous interaction between a northern hairy-nosed wombat and an echidna

Chemists discover how key contrast agent works, paving a way to create new markers needed for correlative microscopy that can image the structure and signaling of cells at the same time.

Researchers have developed a robotic leg with artificial muscles. Inspired by living creatures, it jumps across different terrains in an agile and energy-efficient manner.

Researchers have developed a robotic leg with artificial muscles. Inspired by living creatures, it jumps across different terrains in an agile and energy-efficient manner.

A new molecular engineering technique can precisely influence the development of organoids. Microbeads made of specifically folded DNA are used to release growth factors or other signal molecules inside the tissue structures. This gives rise to considerably more complex organoids that imitate the respective tissues much better and have a more realistic cell mix than before.

Cement-based materials provide a potential solution for mitigating climate change by trapping and storing atmospheric carbon dioxide as minerals, via a process known as carbonation. Despite extensive studies, however, the exact mechanism of this process is not yet understood. Now, researchers have conducted a comprehensive investigation of carbonation reaction using a new method, revealing the role of structural changes and water transport, paving the way for advanced carbon dioxide-absorbing building materials.

Converting biomass such as waste cooking oil into useful chemicals through catalysis can help create a more sustainable chemical industry. However, conventional techniques require enormous energy and generate harmful chemicals. Moreover, such techniques reduce the lifetime of catalysts. Now, researchers reveal a zeolite catalyst that can be efficiently heated up using microwaves.

Well, it was a grueling 15¼-hour flight from Cape Town to Dulles Airport in the Virginia suburbs of Washington, D.C.,  and that was on top of a five-hour wait for my plane at Cape Town International Airport, resulting from an 8 p.m. departure when I had to check out of the hotel a bit after noon.

I tried to sleep on the plane, but it was largely futile. So, as usual, I watched a passel of movies, which included the first film (1972) of the movie trilogy “The Godfather” directed by Francis Ford Coppola.  After watching the whole three-hour movie carefully (and for about the fifth time), my opinion is only strengthened that this is one of the best American movies ever made (my top choice, which I’ve often mentioned is “The Last Picture Show,” released a year before “The Godfather”).

I know some people don’t or can’t rank movies, but if you’re daring enough to do so, I’d be delighted to hear readers’ choices for Best American Movie. (As for best foreign films, I’d choose two Japanese ones: Kurosawa’s “Ikiru” (1952) and Ozu’s “Tokyo Story” (1953).

BTW, I had forgotten that Marlon Brando, playing Don Corleone, is not the first character to speak in the movie; rather, it’s an undertaker asking the Godfather to exact justice on the undertaker’s daughter, beaten up by a gang of sexual predators. The first sign of the Godfather is the movement of his hand at 1:30. Here are the first 6.5 minutes:

The movie won the Oscar for Best Picture, and Brando nabbed it for Best Actor, but declined the award. It won a third Oscar for Best Adapted Screenplay, shared by Coppola and author Mario Puzo.

I’m now cooling my heels at Dulles for two hours, waiting for the 2.5-hour flight to Chicago. After that it’ll be another 1.5-2 hours before I get home. It’s been a long, long flight, but less grueling than my canceled flight to South Africa, which I rebooked flying (after our flight to Cape Town to Dulles was canceled) from Dulles to Newark, then from Newark to Johannesburg, and then from Joburg to Cape Town.

I still have at least two photo-and-text posts left for South Africa, including a visit to the Kirstenbosch National Botanical Garden in southern Cape Town, perhaps the best such garden I’ve ever seen. I hae photos of many flowers, including the resplendent King Protea (Protea cynaroides), the national flower of South Africa. Here’s a preview (these flowers can be as much as a foot across):

Meanwhile, in Dobrzyn, Hili is being a typical cat:

A: Here you are!
Hili: Yes, because it’s a good place for a siesta.

Ja: Tu jesteś!
Hili: Tak, bo to dobre miejsce na siestę.

Shortly after endorsing Donald Trump for President, Robert F. Kennedy Jr. claimed he and Trump will "make America healthy again." His proposals to do that range from semi-reasonable to outright quackery.

The post RFK Jr.’s MAHA manifesto: How not to “make America healthy again” first appeared on Science-Based Medicine.

According to Nebula Theory, stars and their systems of planets form when a massive cloud of gas and dust (a nebula) undergoes gravitational collapse at the center, forming a new star. The remaining material from the nebula then forms a disk around the star from which planets, moons, and other bodies will eventually accrete (a protoplanetary disk). This is how Earth and the many bodies that make up the Solar System came together roughly 4.5 billion years ago, eventually settling into their current orbits (after a few migrations and collisions).

However, there is still debate regarding certain details of the planet formation process. On the one hand, there are those who subscribe to the traditional “bottom-up” model, where dust grains gradually collect into larger and larger conglomerations over tens of millions of years. Conversely, you have the “top-down” model, where circumstellar disk material in spiral arms fragments due to gravitational instability. Using the Atacama Large Millimeter/submillimeter Array (ALMA), an international team of astronomers found evidence of the “top-down” model when observing a protoplanetary disk over 500 light-years away.

The team was led by Jessica Speedie, an astronomy and astrophysics Ph.D. candidate at the University of Victoria. She was joined by colleagues from the Kavli Institute for Astronomy and Astrophysics (KIAA-PKU), the Center for Simulational Physics (CSP-UGA), the Cambridge Institute of Astronomy, the Centre de Recherche Astrophysique de Lyon (CNSA-CRAL), the Institute of Astronomy and Astrophysics (ASIAA), the Department of Earth, Atmospheric, and Planetary Sciences (MIT EAPS), the National Astronomical Observatory of Japan (NAOJ), the European Southern Observatory (ESO), and multiple universities and observatories.

The paper that details their research, “Gravitational instability in a planet-forming disk,” was recently published in the journal Nature.

Located in the Atacama desert in the Chilean Andes, ALMA is the largest radio telescope in the world dedicated to studying the parts of the Universe that are otherwise invisible to astronomers. This includes cold dust clouds in space, protoplanetary disks, and some of the earliest galaxies in the Universe, which are only visible at millimeter and submillimeter wavelengths. Using ALMA, Speedie and her colleagues observed the well-characterized protoplanetary disk around AB Aurigae, a young star system (4 million years old) located about 530 light-years from Earth.

The star is a pre-main sequence A-type star (blue-white) approximately 2.5 times the size of our Sun and about 2.4 times as massive. Beginning in 2017, scientists at ALMA began observing the star’s protoplanetary disk to learn more about planet formation in young star systems. Since then, astronomers have observed several developing protoplanets forming in AB Aurigae’s disk, as well as a gas giant nine times the mass of Jupiter that was confirmed in 2022. These appear as clumps within the protoplanetary disk’s spiral arms, rotating counterclockwise around the star.

The detection of these bodies around such a young star raised doubts about the “bottom-up” process. According to this model, these protoplanets did not have nearly enough time to become as large as they have. Along with her PhD advisor Ruobing Dong, Speedie and their team were determined to study how the gas in the system’s vast spiral arms is moving. ALMA’s sensitivity and high velocity resolution was crucial to that task and enabled the team to probe the gas deep within the disk and measure its motion precisely.

Dr. Cassandra Hall, an Assistant Professor of Computational Astrophysics at the University of Georgia was also a co-author on the research. Four years ago, Hall led a study where she and her colleagues (which included Dong and other members of Speedie’s team) simulated how a gravitationally unstable disk would behave. As she indicated in a NRAO press release:

“Disks that are gravitationally unstable should have distinctive ‘wiggles’ in their velocity field, unlike disks that are stable. Back in 2020, we performed some of the most advanced simulations in the world to predict the existence of this hallmark signature of gravitational instability. It was clear, it was testable, and it was a bit scary – if we didn’t find it, then something had to be very, very wrong with our understanding of these disks.”

Spiral arms form in a protoplanetary disk when the disk-to-star mass ratio is sufficiently high. Over time, changes in density lead to changes in gravity, which causes variations in the velocities of gas in and around the spiral arms. These variations in velocity are seen as “wiggles,” and the magnitude can be used to infer the mass ratio between the host star and the material in its disk. Using ALMA’s array of radio antennas, Speedie and her team mapped the velocity of carbon monoxide isotopes within the disk’s spiral arms and looked for indications of the predicted “wiggles.”

These measurements yielded a three-dimensional rectangular “data cube” that mapped gas velocity and position within the protoplanetary disk along the observatory’s line of sight. As is customary with ALMA’s interferometry measurements, the data was parsed into “slices” (or strategically oriented cuts), allowing Speedie and her team to conclusively identify the velocity wiggle indicating gravitational instability. This constitutes the first direct observational confirmation that the “top-down” pathway to planet formation is correct.

What’s more, it indicates that planetary systems may form much faster than previously thought, which could have significant implications for astrogeology and exoplanet research. As Speedie explained, Hall’s work, ALMA’s sensitivity, and the quality data products it created for them were what made this discovery possible:

“This is a classic science story of, ‘we predicted it, and then we found it’. The Hall-mark of gravitational instability. We worked with one of the deepest ALMA observations taken with such high-velocity resolution toward a single protoplanetary disk to date. The ALMA data provides a clear diagnosis of gravitational instability in action. There is no other mechanism we know of that can create the global architecture of spiral structure and velocity patterns that we observe.”

In the near future, Speedie and her colleagues plan to continue using ALMA to learn more about how planetary systems form around young stars. As part of the NFS/NRAO ALMA ambassador program, Speedie is training alongside other postdoctoral students and early career astronomers to share ALMA’s resources and capabilities with the wider astronomical community.

Further Reading: NRAO, Nature

The post ALMA Detects Hallmark “Wiggle” of Gravitational Instability in Planet-Forming Disk appeared first on Universe Today.

In 2012, two previous dark matter detection experiments—the Large Underground Xenon (LUX) and ZonEd Proportional scintillation in Liquid Noble gases (ZEPLIN)—came together to form the LUX-ZEPLIN (LZ) experiment. Since it commenced operations, this collaboration has conducted the most sensitive search ever mounted for Weakly Interacting Massive Particles (WIMPs) – one of the leading Dark Matter candidates. This collaboration includes around 250 scientists from 39 institutions in the U.S., U.K., Portugal, Switzerland, South Korea, and Australia.

On Monday, August 26th, the latest results from the LUX-ZEPLIN project were shared at two scientific conferences. These results were celebrated by scientists at the University of Albany‘s Department of Physics, including Associate Professors Cecilia Levy and Matthew Szydagis (two members of the experiment). This latest result is nearly five times more sensitive than the previous result and found no evidence of WIMPs above a mass of 9 GeV/c2. These are the best-ever limits on WIMPS and a crucial step toward finding the mysterious invisible mass that makes up 85% of the Universe.

Led by the Department of Energy’s (DoE) Lawrence Berkeley National Laboratory, the LZ experiment is located at the Sanford Underground Research Facility in South Dakota, about 1,500 meters (nearly a mile) beneath the surface. The experiment relies on an ultra-sensitive detector made of 10 tonnes (11 U.S. tons) of liquid xenon to hunt for the elusive signals caused by WIMP-nucleus interactions. While direct detections are yet to be made, these latest results have helped scientists narrow the search.

As Levy explained in a recent UofA press release:

“Dark matter interacts very, very rarely with normal matter, but we don’t know exactly how rarely. The way we measure it is through this cross-section or how probable an interaction is within our detector. Depending on the mass of a dark matter particle, which we don’t know yet, an interaction within the detector is more or less probable. What the new LZ results tell us is that dark matter interacts with normal matter even more rarely than we thought, and the only instrument in the world that is sensitive enough to measure that is LZ.”

The existence and nature of Dark Matter are among the greatest mysteries in modern astrophysics. Originally proposed to explain the rotational curves of galaxies, the existence of Dark Matter is vital to the most widely accepted cosmological model – the Lambda Cold Dark Matter (LCDM) model. Unfortunately, according to the prevailing theories, DM only interacts with normal (aka. “luminous”) matter via gravity, the weakest of the four fundamental forces. Detecting these interactions requires incredibly sensitive instruments and an environment free of electromagnetic energy (including heat and light).

While no direct detections have been made, the latest results from LZ have narrowed the range of possibilities for one of the leading DM candidates. As Szydagis said:

“It’s often misunderstood what is meant by the phrase ‘world’s best dark matter experiment’ since no one has made a conclusive, unambiguous discovery yet. However, new, stricter null results like LZ’s are still extremely valuable for science. UAlbany, as one part of the multinational collaboration that is LZ, has been making important contributions ensuring the robustness of LZ’s results, going back to the very beginning of the experiment.”

Although DM remains “invisible” to us, the presence of its gravitational pull is fundamental to our understanding of the Universe. For example, the formation and movement of galaxies are attributed to DM, and its existence is vital for explaining the large-scale structure and evolution of the Universe. If DM does not exist, then our understanding of gravity – as described by Einstein’s Theory of General Relativity – is essentially wrong and needs revision. However, General Relativity has been experimentally validated again and again over the past century.

Therefore, narrowing the search for its constituent particle is vital to proving that our foundational theories about the Universe are correct. As Levy noted, UAlbany scientists have been making integral contributions to LZ for over a decade, and their work is far from done! “Working on LZ is always so exciting, even if we still have not made a discovery yet,” she said. “We all know that if it were easy, someone else would have done it already! I think right now what we need to take out of this result is that LZ is a great team of scientists, our detector is working superbly, our analysis is extremely robust, and we are nowhere near done taking data.”

Further Reading: University at Albany

The post Largest Dark Matter Detector is Narrowing Down Dark Matter Candidate appeared first on Universe Today.

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From precognitive dreams and telepathic visions to near-death experiences, UFO encounters, and beyond, so-called impossible phenomena are not supposed to happen. But they do happen—all the time. Jeffrey J. Kripal asserts that the impossible is a function not of reality but of our everchanging assumptions about what is real. How to Think Impossibly invites us to think about these fantastic (yet commonplace) experiences as an essential part of being human, expressive of a deeply shared reality that is neither mental nor material but gives rise to both. Thinking with specific individuals and their extraordinary experiences in vulnerable, open, and often humorous ways, Kripal interweaves humanistic and scientific inquiry to foster an awareness that the fantastic is real, the supernatural is super natural, and the impossible is possible.

Jeffrey J. Kripal holds the J. Newton Rayzor Chair in Philosophy and Religious Thought at Rice University. He is the author of numerous books, including The Superhumanities: Historical Precedents, Moral Objections, New Realities, The Flip: Epiphanies of Mind and the Future of Knowledge, Authors of the Impossible: The Paranormal and the Sacred, Esalen: America and the Religion of No Religion, Mutants and Mystics: Science Fiction, Superhero Comics, and the Paranormal, and just published, also by the University of Chicago Press, How to Think Impossibly: About Souls, UFOs, Time, Belief, and Everything Else.

If you enjoy the podcast, please show your support by making a $5 or $10 monthly donation.

Medical clowns, who play with children in hospitals, may help them be discharged sooner by reducing their heart rates

If all goes well I’ll be flying home this evening, changing planes in Dulles after a 15-hour flight, and arriving in Chicago tomorrow morning. I’ll be a wreck, of course, but that’s expected after a long trip like that. Regular posting here will begin after I start recovering from jet lag.  But today we have a post on my visit (more of a pilgrimage, really) to Robben Island.

Like Alcatraz in San Francisco Bay, South Africa’s Robben Island has, in the last few hundred years, served as a repository for the most ostracized of criminals, though Robben is most famous for the last century’s political prisoners rather than common criminals. And, of course, the most famous among these was Nelson Mandela, who spent 18 of his 27 years of incarceration on Robben (see his cell below).

And, like Alcatraz, Robben is within viewing distance of a lovely city (it’s 11 km from Cape Town), which of course would tantalize the prisoners, who could see freedom so close. Below is a Wikipedia aerial photo of Robben Island, with Cape Town and Table Mountain in the distance. The prison is the group of buildings directly in line with the wharf.

As far as I know, only one person, the black political prisoner David Stuurman, escaped from Robben Island. That was in the early 19th century, and he did it twice, by boat.  He eventually was deported to Australia, where he died. But, like Alcatraz, nobody is known to have escaped Robben by swimming. The water is cold and the distance to Cape Town is great.

Note that Robben is only a few meters above sea level, and that distance is shrinking with global warming.

South African Tourism from South Africa, CC BY 2.0, via Wikimedia Commons

Robben Island is a UNESCO World Heritage site, so designated because of its “outstanding universal value”. The UNESCO page says this:

Robben Island was used at various times between the 17th century and the 20th century as a prison, a hospital for socially unacceptable groups, and a military base. Its buildings, and in particular those of the late 20th century maximum security prison for political prisoners, testify to the way in which democracy and freedom triumphed over oppression and racism.

What survives from its episodic history are 17th century quarries, the tomb of Hadije Kramat who died in 1755, 19th century ‘village’ administrative buildings including a chapel and parsonage, small lighthouse, the lepers’ church, the only remains of a leper colony, derelict World War II military structures around the harbour and the stark and functional maximum security prison of the Apartheid period began in the 1960s.

The symbolic value of Robben Island lies in its somber history, as a prison and a hospital for unfortunates who were sequestered as being socially undesirable. This came to an end in the 1990s when the inhuman Apartheid regime was rejected by the South African people and the political prisoners who had been incarcerated on the Island received their freedom after many years.

Criterion (iii): The buildings of Robben Island bear eloquent witness to its sombre history.

Criterion (vi):Robben Island and its prison buildings symbolize the triumph of the human spirit, of freedom and of democracy over oppression.

But really, I think that if Nelson Mandela hadn’t spent 18 of his 27 years in prison on Robben, and then gone on to win a Nobel Peace Prize and become President of South Africa as well as President of the African National Congress, then Robben wouldn’t be nearly as well known, or have become a tourist destination.

I went mainly because of Mandela, and especially to see the conditions he endured for 18 years. He is one of my heroes, and his refusal to promulgate divisive hatred after he was released and became President is one of the great conciliatory and humane gestures of history.

But we should remember that many other political prisoners—some of them very well nown—were housed there, too, often for decades. It was the maximum-security prison for blacks and Asians that the white government considered dangerous (no white prisoners were housed there, though all the guards were white).  And now that South Africa is a democracy, the site could indeed be feted as more than a place where Mandela was imprisoned: it could be seen as demonstrating the triumph of the human desire for freedom over bigotry and authoritarianism.

Tours to Robben Island take about 3.5 hours, with 1.5 hours or so traveling to the island and the other two hours for the tour, which consists of a bus drive around the island followed by a tour on foot with a guide, often a former inmate. You’re advised to book in advance, as the slots sell out quickly (I booked two weeks in advance.)

It was an overcast day, with clouds floating around Table Mountain, but the views of Cape Town and surrounding mountains are spectacular both entering and leaving the city. As you can see, Table Mountain is flat like a table, looming high above the city. Taking the cable car to the top for the view is a must-do for visitors, but, sadly, I just couldn’t fit it in.

Below is the entry to the prison complex as well as the rest of the island, which still houses a town for those who maintain the site.  There is also a colony of African penguins (the same species as in Cape Town), as well as assorted smaller wildlife (see below).  Sadly, as in other places in South Africa, the penguin population is declining, almost certainly because of competition from human overfishing.

Below is the entrance to Robben Island, though I’m not at all sure it’s what the entrance looked like in the days of apartheid.  The site “Shadows on the Grass” says this about the entrance, and then goes on to describe how poorly the prisoners were treated:

These are the words written above the entrance gate to Robben Island. A sort of sick irony and blatant lie, symbolic of the methods used by the apartheid regime to try and break the spirit of the political prisoners from 1961 to 1991.

. . . . Originally named Robbeneiland, Dutch for Seal Island, the low lying kilometre wide piece of land is arid with no water sources. From 1836 to 1931, the island was used as a leper colony (Hansen’s Disease) and during the second World War, allied forces used it as a gun fortification.

During apartheid, the regime converted Robben Island into a maximum security prison. Betwee 1961 and 1991, over three thousand men was incarcerated for political crimes, including the former president and Nobel Laureate Nelson Mandela.

. . . The visitor center, near the front gate was used by prisoners as often as once every six months. Visits must be booked a year in advance, even though they lasted only a half hour in length. Often times, to break the spirits of the captives, guards would tell family members who had travelled from as far away as Namibia, JoBerg, and Natal that their loved ones were ill and could not come see their relatives behind the glass. At the same time they might tell the prisoners that the family had missed the ferry or could not afford the train down to Cape Town. Additionally, all conversation between visitors had to be conducted in Afrikaans or English, the languages of the guards- not their native tongues like Xhosa, isiZulu et… We also stopped at the lime quarry where prisoners like Madiba [Nelson Mandela] worked for 13 years in blinding light without protection or shoes. Many of the former prisoners have undergone eye procedures to correct sun and dust damage.

Our guide (see below) says that because many prisoners could speak neither Afrikaans nor English, and couldn’t speak their native languages under any circumstances when the guards were listening, the yearly half-hour visits were often conducted in silence.

A graveyard (taken from a fast-moving bus) where inhabitants of the island are buried. I’m not sure if any of these are prisoners as opposed to others who worked on the island or sufferers from leprosy (Hansen’s Disease):

Here is the limestone quarry where the prisoners worked—for many hours a day.  There was no need to have them do this, but the hard labor was consider part of their punishment. The harsh sunlight and glare from the rocks, combined with rock dust, hurt the eyes of many prisoners, including Mandela. 

Below: our guide, who was also a political prisoner. I asked him how long he spent on the island and he said “eighteen years”—the same as Mandela. He added that he was in as a political prisoner and also for having a firearm.

In the famous Rivonia Trial of 1964, Mandela and seven others were sentenced to life imprisonment for sabotage and conspiring to overthrow the government through violent acts. Mandela admitted to sabotage but denied the other charges, and gave a famous three-hour speech, called “I am prepared to die” when the defense presented its case. This is the speech’s ending:

During my lifetime I have dedicated my life to this struggle of the African people. I have fought against white domination, and I have fought against black domination. I have cherished the ideal of a democratic and free society in which all persons will live together in harmony and with equal opportunities. It is an ideal for which I hope to live for and to see realised. But, My Lord, if it needs be, it is an ideal for which I am prepared to die.

Mandela was to serve 18 years (1964-1982) on Robben Island and then spent 8 more years in two mainland prisons. He was finally released in 1990.

Besides working in the limestone quarry, the prisoners spent many days sitting the the courtyard outside their cell, breaking rocks. Here’s a photo of a photo hanging on the wall of the prison, showing the rock-breaking. This is the same courtyard where Mandela got the prison to allow a small garden, which, not coincidentally, is where he buried his political writings. See below for a modern view.

In memory of those times, Mandela, revisiting the island, put down a single rock, which was supplemented by single rocks added by other re-visiting prisoners. The picture and caption below show the rock pile from the Wikipedia article on Robben Island:

(from Wikipedia): Rock pile started by Nelson Mandela and added to—one rock at a time—by former prisoners returning to the island. Credit: D. Gordon E. Robertson, CC BY-SA 3.0 , via Wikimedia Commons

Below: the house on the left was that of Robert Sobukwe (1924-1978), another anti-apartheid activist described by Wikipedia:

In March 1960, Sobukwe organized and launched a non-violent protest campaign against pass laws, for which he was sentenced to three years in prison on grounds of incitement. In 1963, the enactment of the “Sobukwe Clause,” allowed an indefinite renewal of his prison sentence, and Sobukwe was subsequently relocated to Robben Island for solitary confinement. At the end of his sixth year at Robben Island, he was released and placed under house arrest until his death in 1978.

But for reasons that are unclear, Sobukwe had privileges that other prisoners didn’t, although, unlike other prisoners, he was kept in solitary confinement.

Sobukwe was kept in solitary confinement but enjoyed a unique prisoner-plus status; he was permitted certain privileges including books, magazines, newspapers, civilian clothing, etc. He lived in a separate area on the island and was strictly prohibited from contact with other prisoners, though Sobukwe was able to communicate sporadically through visual signals while outside for exercise.

His house is the big house to the left; I presume the other buildings contain individual cells.

The buildings that held the political prisoners:

Some prisoners were allowed outside exercise and games; here’s a rugby field they constructed. (By the way, congrats to the Springboks for their victory over New Zealand’s All Blacks yesterday.)

This shows the food provided to prisoners, which differed according to their apartheid classification: Asians and “coloureds” (blacks with white genes) got food different from the “Bantus” (native African blacks). “Mealie meal” is corn porridge, presumably like “pap”.  Either way, the prisoners didn’t eat well (where are the vegetables?) and weren’t given much time to eat (just a few minutes in the limestone quarry, we were told):

Prisoners were allowed to receive and to write one letter every six months, but these were read and censored, with any material eliminated that might be considered political. Here’s one censored letter from Durban displayed on the wall of the prison:

The first part of the waking tour of the prison involved showing us two large halls, one full of bunk beds. I’m not sure what these were, as I was was too far behind the guide to hear him, but perhaps they were for non-political prisoners. If you’ve been to Robben or know the answer, please weigh in below.

Mandela was instrumental in getting the prison to allow a small garden to be planted in the courtyard.

The garden area (below) had little greenery (perhaps it was the time of year) and one leafless apple tree. It served more than just a place to see a little greenery, for it was in this garden that Mandela buried some of his political writings, including the manuscript of his best-selling autobiography, Long Walk to Freedom, not published until 1994.

When we were in the “garden” area, our guide told us that Mandela’s cell was the fourth window on the right above, and of course I waited until the group had passed so I could see it and photograph it without a crowd.

Here’s where the man spent 18 years. It’s only about 6 m²  (7 x 9 feet).  The light was kept in all the cells night and day. Prisoners, as you can see, slept on the floor on a mat, and had almost no amenities. Here we see a table, a plate, cup, and utensil, and what looks like a slop bucket.

Another view, this time taken with a flash.  Mandela did his writing at night, which I believe extended from 6 pm to 6 am.

Here’s the outside of the prison taken as a panorama. Click the photo to enlarge it.

While exiting the grounds I came upon this turtle. Reader Divy and her husband, who run a veterinary business and have extensive knowledge of reptiles, agreed this is an Angulate tortoise (Chersina angulata), known to be found in Robben Island.

On the way to the exit from the grounds was this room, which was an office without any X-ray machines. I suspect it was part of the facilities when the prison was in operation.

And the exit to the harbor (the other side of the entrance).  I imagined how happy a prisoner was to be walking out this gate to freedom.

Finally, after a choppy trip back to the mainland, we encountered a trio of brown fur seals (Arctocephalus pusillus). There are two subspecies with a curiously disjunct distribution, one living at the southern tip of Africa and the other in a strip of southeast Australia.

And, with the sight of a proud seal, we’re back.

Meanwhile, in Dobrzyn, Hili is observant:

Hili: A ladybird.*
A: So what about it?
Hili: Nothing, I’m just stating the fact.

Hili: Biedronka.
Ja: I co z tego?
Hili: Nic, stwierdzam fakt.

 

*Hili obviously translates herself into English English – for US readers, a biedronka is a ladybug – MC

Drs. Jay Bhattacharya, Scott Atlas, and Marty Makary are also set to speak at Stanford next month

The post Hopkins Business School to Platform COVID-19 Contrarians at Health Policy Symposium first appeared on Science-Based Medicine.

Throughout Earth’s history, the planet’s surface has been regularly impacted by comets, meteors, and the occasional large asteroid. While these events were often destructive, sometimes to the point of triggering a mass extinction, they may have also played an important role in the emergence of life on Earth. This is especially true of the Hadean Era (ca. 4.1 to 3.8 billion years ago) and the Late Heavy Bombardment, when Earth and other planets in the inner Solar System were impacted by a disproportionately high number of asteroids and comets.

These impactors are thought to have been how water was delivered to the inner Solar System and possibly the building blocks of life. But what of the many icy bodies in the outer Solar System, the natural satellites that orbit gas giants and have liquid water oceans in their interiors (i.e., Europa, Enceladus, Titan, and others)? According to a recent study led by researchers from Johns Hopkins University, impact events on these “Ocean Worlds” could have significantly contributed to surface and subsurface chemistry that could have led to the emergence of life.

The team was led by Shannon M. MacKenzie, a planetary scientist, and her colleagues at Johns Hopkins University Applied Physics Laboratory (JHUAPL). They were joined by researchers from Dartmouth’s Thayer School of Engineering, the University of Western Ontario, Curtin University’s School of Earth and Planetary Sciences, the Planetary Habitability Laboratory (PHL) at UPR at Arecibo, Jacobs Technology, NASA’s Jet Propulsion Laboratory, and the Astromaterials Research and Exploration Science (ARES) at NASA Johnson Space Center. The paper that details their findings recently appeared in The Planetary Science Journal.

Voyager 1 image of Valhalla, a multi-ring impact structure 3,800 km (2,360 mi) in diameter.
Credit: NASA/JPL Exogenesis

As indicated in their paper, impacts from asteroids, comets, and large meteors are more often associated with destruction and extinction-level events. However, multiple lines of evidence indicate that these same types of impacts may have supported the emergence of life on Earth roughly 4 billion years ago. These events not only delivered volatiles (such as water, ammonia, and methane) and organic molecules, but modern research indicates that they also created new substrates and compounds essential to life.

Moreover, they created a variety of environments that were essential to the emergence and sustainment of life on Earth. As they wrote:

“Exogenously delivered materials have been estimated to be an important source of organics on early Earth. Shockwaves could provide the energy for organic synthesis of important precursors like HCN or amino acids. The iron and heat from very large impactors can facilitate the reducing atmospheric conditions necessary for abundant HCN production. Impacts fracture and, in typical terrestrial events, melt the target: the more permeable substrates and excavation of deeper rock layers promote hydrothermal activity and endolithic habitats.”

According to the latest fossilized evidence, the earliest life forms emerged on Earth roughly 4.28 billion years ago. These fossils were recovered from hydrothermal vent precipitates in the Nuvvuagittuq Greenstone Belt in northern Quebec, Canada, confirming that hydrothermal activity played a vital role in the emergence of life on Earth. But what about the many “Ocean Worlds” that reside in the outer Solar System? This includes bodies like Europa, Ganymede, Enceladus, and Titan, as well as Uranus’ moons Ariel and Titania, Neptune’s moon Triton, and Trans-Neptunian bodies like Pluto, Charon, and possibly more.

Ocean Worlds

This term refers to bodies predominantly composed of volatile elements such as water and differentiated between an icy crust and a rocky and metallic core. At the core-mantle boundary, tidal flexing (the result of gravitational interaction with another body) causes a buildup of heat and energy released via hydrothermal vents into the ice. This allows these worlds to maintain oceans of liquid water in their interiors. In short, these worlds have all the necessary ingredients for life: water, the requisite chemical compounds, and energy.

Impact velocity and first contact pressure estimates for potential icy and rocky impactors on “Ocean Worlds.” Credit: Mackenzie, S.M. et al. (2024)

Furthermore, data from the NASA/ESA Cassini–Huygens mission confirmed that the plumes regularly erupting from Enceladus’ southern polar region contain organic molecules. Last but not least, the presence of surface craters indicates that these bodies have experienced surface impacts throughout their history. The question naturally arises: could impacts have delivered the necessary building blocks of life to “Ocean Worlds” the same way they delivered them to the inner Solar System? And if so, what does that mean about their potential habitability today? As the team wrote in their paper:

“Impact processes are likely an important part of the answers to these questions, as impacts can drive exchange through the ice crust—either through direct seeding or flushing through the crust—and therefore drive episodic influxes of organic and inorganic materials from the surface and/or from the impactor itself. Impacts can also generate ephemeral microcosms: any liquid water melted during impact freezes out over timescales commensurate with the impact energy.”

“The exciting potential for chemistry within these pockets has been established, from concentrating salts to driving amino acid synthesis. Furthermore, shock-driven chemistry of icy, sometimes organic-rich (in the case of Titan especially) target materials may generate new “seed” compounds (e.g., amino acids or nucleotides) in the melt pool.”

Investigation

The first step for MacKenzie and her team was to investigate the initial shock levels created by the most common impacts for Ocean Worlds—comets that likely originated from the Kuiper Belt and Oort Cloud. To do this, the team calculated the velocities and maximum pressure that would be achieved by impacts involving icy and rocky bodies. They also considered how this would vary based on different families (primary or secondary impacts) and which systems were involved – i.e., Jupiter or Saturn. Whereas primary impacts involve comets or asteroids, secondary impacts are caused by the ejecta they create.

In the case of the Jupiter and Saturn systems, secondary impactors may be icy or rocky depending on where they originated (an icy body like Europa, Enceladus, and Titan, a rocky body like Io and larger asteroids). Whereas primary impacts have higher velocities and produce larger melt volumes), secondary impacts are more frequent. To determine melt sizes, the team consulted observed crater sizes on Europa, Enceladus, and Titan, and dynamic models that calculate the cumulative rate of cratering over time. They then compared the peak pressures at impact to thresholds for the survivability of elements essential to life, organic molecules, amino acids, and even microbes identified in previous studies.

Cumulative cratering rates assuming heliocentric, cometary impactors. Credit: Mackenzie, S.M. et al. (2024)

From this, they determined that most impacts at Europa and Enceladus experience peak pressures greater than what bacterial spores can survive. However, they also determined that a significant amount of material still survives these impacts and that higher first-contact pressures could also facilitate the synthesis of organic compounds in the meltwater that fills the craters. Meanwhile, on average, Titan and Enceladus experienced impacts with lower impact velocities, creating peak pressures that fall within the tolerance range for both bacterial spores and amino acids.

The next step was to consider how long fresh craters would survive and whether this would be sufficient for synthesizing biological materials. Based on the observed crater sizes on Enceladus and Europa, they determined that the longest-lived craters last only a few hundred years, whereas Titan could take centuries to tens of thousands of years for fresh craters to freeze. While Europa and Enceladus experience more high-velocity impacts (due to Titan’s dense atmosphere), the long-lived nature of Titan’s craters means that all three bodies have a chance for organic chemistry experiments to occur.

They also considered resurfacing rates on Europa, Enceladus, and Titan and how these would cycle biological material to their interiors. In all three cases, the satellites have relatively “young” terrain, implying regular resurfacing events.

Results

Based on these considerations, Mackenzie and her team determined that melts produced by comet impacts on Europa, Enceladus, and Titan have been frequent and long-lived enough to be of astrobiological interest. However, this varies based on the composition of the comets and the surface ice in question. As they summarized:

“At Europa and Enceladus, the survival and deposition of impactor organics is more important as there are fewer surface organics within the ice crust to seed the melt pool. On Titan, the survival of elements like phosphorous may be more important. Thus, even the small, more frequent impact events contribute to the astrobiological potential by delivering less modified compounds to the surface that are available either for immediate reaction if melt is produced or for future processing (including in subsequent impact events).”

Total melt production for observed craters on Enceladus (cyan) and Titan (orange), binned by observed crater diameter. Credit: Mackenzie, S.M. et al. (2024)

For instance, they found that a comet impacting Europa at the average impact velocity would create a 15 km (9.3 mi) crater and provide ~1 km3 (0.24 mi3)of meltwater. Based on the abundance of glycine (an essential amino acid) found on the comet 67P Churyumov–Gerasimenko, they determined that several parts per million would survive – roughly three orders of magnitude higher than what has been observed forming around hydrothermal vents here on Earth. “Thus, impactors seed whatever chemistry happens in the melt, providing organic and other essential elements depending on the impactor composition,” they added.

While this does not necessarily mean that these and other “Ocean Worlds” are currently habitable or actively support life, they demonstrate potential for future study. In the coming years, missions like the ESA’s JUpiter ICy moons Explorer (JUICE), and NASA’s Europa Clipper and Dragonfly missions will reach Ganymede, Europa, and Titan (respectively). There are also plans to create an Enceladus Orbiter to pick up where the Cassini-Huygens probe left off by examining Enceladus’ plume activity more closely.

Therefore, conducting in-situ sampling and analysis on these moons could provide powerful insight into prebiotic chemical pathways and determine under what conditions life can emerge. These sample studies will also address the larger question of whether or not life could exist in the interiors of “Ocean Worlds,” providing a preview of what future missions prepared to explore beneath the ice will find.

Further Reading: The Planetary Science Journal

The post Could Comets have Delivered the Building Blocks of Life to “Ocean Worlds” like Europa, Enceladus, and Titan too? appeared first on Universe Today.

When you walk across your lawn or down the street, you move on the surface of a surprisingly layered world. Some of those layers are rock, others are molten. A surprising amount of water is mixed into those layers, as well. It turns out that most planets have more of it “deep down” than we imagined.

Most of a planet’s water isn’t on the surface, even though we see oceans, lakes, and rivers here on Earth. The heart of our planet is iron, and covered by silicate rock layers. Scientists have long used our planet’s makeup as a sort of “model” for rocky exoplanets around other stars. That model may be outdated and too simplistic, according to Professor Caroline Dorn at ETH Zurich. “It is only in recent years that we have begun to realize that planets are more complex than we had thought,” she said. Dorn has been collaborating with Haiyang Luo and Jie Deng from Princeton University to understand the distribution of water mixed with silicates and iron inside a planet. They used computer simulations to come up with a robust model of the distribution of water on exoplanets.

Recent investigations of Earth’s water content triggered the team’s work. It turned out that our oceans contain only a small fraction of the overall water budget. The interior could be hiding the equivalent of 80% of the surface oceans. That raised a big question: could other planets have similarly hidden reservoirs?

Planets and Water

To answer that question, the science team simulated how water behaves in the conditions present when planets are young. Many known exoplanets orbit close to their stars, which means they’re likely to be hot worlds. They probably have oceans of molten magma that haven’t yet solidified to make silicate bedrock mantles.

Artist’s impression of a lava world. The exoplanet K2-141b is so close to its host star that it likely has magma oceans and surface temperatures over 3000 degrees. Water may be mixed in with the magma. c. ESO

As it turns out water dissolves very well in these magma oceans. The iron core takes time to develop,” she said. “A large share of the iron is initially contained in the hot magma soup in the form of droplets,” she explained, noting that water sequestered in this soup combines with the iron droplets and sinks with them to the core. “The iron droplets behave like a lift that is conveyed downwards by the water,” Dorn said.

That kind of mixing of iron and water happened in the moderate pressure environment in Earth’s interior. Larger planets with higher interior pressures presented a challenge to understand. It turns out they mix water and iron, too. “The larger the planet and the greater its mass, the more the water tends to go with the iron droplets and become integrated in the core,” said Dorn. “Under certain circumstances, iron can absorb up to 70 times more water than silicates. However, owing to the enormous pressure at the core, the water no longer takes the form of H2O molecules but is present in hydrogen and oxygen.”

Evolving Planets over Time

This result is a big deal if you want to understand how planets form and develop. That’s because the water never escapes the planet’s core. However, under the right conditions, water mixed in with the magma ocean can “de-gas” under the right conditions. Essentially, it separates and rises to the surface as the magma cools and forms the mantle. “So if we find water in a planet’s atmosphere, there is probably a great deal more in its interior,” explained Dorn.

That gives a lot of new information to use as scientists search for planets around other stars and look for habitable worlds. In particular, astronomers using the JWST can track the types of molecules in exoplanet atmospheres and use that information to find habitable worlds. “Only the composition of the upper atmosphere of exoplanets can be measured directly,” said Dorn. “Our group wishes to make the connection from the atmosphere to the inner depths of celestial bodies.”

TOI-270d appears to be a super-Earth or Earth-type planet, as shown in this artists’ concept. Could it have water hidden in its core that could boost its habitability. Courtesy Martin Vargic CC BY 3.0

Currently, the team studies exoplanet TOI-270d. “Evidence has been collected there of the actual existence of such interactions between the magma ocean in its interior and the atmosphere,” said Dorn. It’s at the top of her list of interesting objects to examine more closely for water, along with another one called K2-18b. It seems to be a promising candidate for habitability as well.

So, Does Deep Water Imply Life or Habitability?

Since water is important in the search for life-bearing worlds, looking for wet Earth-type and super-Earth worlds is the next step in searching out life. Dorn’s team found that planets with these deep water layers are likely to be fairly rare. That’s because most of their water is not on the surface. In other words, they may not be ocean worlds, but places with water trapped in their cores.

That’s not all bad. The science team assumes that even planets with a relatively high water content could have the potential to develop Earth-like habitable conditions. Dorn’s team may give scientists new ways to look for water-abundant worlds.

For More Information

Planets Contain More Water Than Thought
The Interior as the Dominant Water Reservoir in Super-Earths and Sub-Neptunes

The post There’s More Water Inside Planets Than We Thought appeared first on Universe Today.