First discovered by specialists in 1994, the world’s deepest sinkhole can be found in Fengjie County, Chongqing Municipality, China. Xiaozhai Tiankeng, or the Xiaozhai Heavenly Pit, measures roughly 537 meters (1,762 feet) in diameter and sinks between 511 and 662 meters (1,667-2,172 feet) into the Earth.

With near vertical walls, the volume of this momentous geological feature is a whopping 119.349 million cubic meters (around 4.2 billion cubic feet). During heavy rains, a waterfall can sometimes be seen cascading down the hole’s steep walls. The structure is double nested, meaning it’s comprised of two distinct “bowls” dissecting it into two layers, with each bowl measuring over 300 meters (984 feet) deep.

The Difeng cave, which the sinkhole sits atop, was formed by a powerful underground river. This river can now be seen in the depths of the pit where it carries clear water through the inner cave systems.

The river runs for approximately 8.5 kilometers (5.3 miles) from the underground Tianjing fissure gorge before reaching daylight at the vertical cliff of the Migong River where the underground water system forms a 46-meter (151-foot) high waterfall.

There are 1,285 species of registered plant in the depths of the Xiaozhai sinkhole, creating its own thriving, unique, and rare ecosystem. Ginkgo biloba, a rare species of tree, can be found living in the pit, as well as rare animal species like the clouded leopard, of which there are estimated to be fewer than 10,000 in the wild. 

Found in a large karst area, the sinkhole is comprised of Triassic limestone found in thick pure blocks. It is believed to have formed gradually throughout the last 128,000 years, making it relatively young in age when compared to other sinkholes in the area.

In fact, China is home to a number of sinkholes, referred to generally as “tiankeng”. The word tiankeng means “heavenly pit” or “sky hole” in Chinese, and refers to a very specific group of geological structures.

To be a tiankeng, the sinkhole must be at least 100 meters (328 feet) deep and wide, with a river flowing through the bottom. All tiankeng are comprised of carbonate rock, with the exception of two Venezuelan structures that consist of sandstone. They’re formed through a karst process when their composition is carbonate rock, and a suffusion process when made of sandstone.

The conditions required to form a tiankeng are very specific, making their formation rare. The rock must be above sea level, and be thick with no layers of impurities. Heavy rain is also required to form these structures, which in turn helps form their underground rivers.

Although the term refers to any sinkhole within these criteria, of the 75 identified, 50 of the largest are found in China, hence the Chinese term becoming the commonplace name for such structures.

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The Bulletin of the Atomic Scientists has announced that the Doomsday Clock has moved forward to 90 seconds to midnight in 2023. Midnight represents "doomsday", so the closer the clock moves to the fateful time, the closer we are to a catastrophe that could wipe out humanity. This is now the closest it has ever been. For the last three years, the clock has been placed at 100 seconds to midnight, the closest it had ever been to doomsday since its creation in the late 1940s. This year’s announcement doesn’t come as too much of a surprise, though.

"We at the Bulletin believe that because humans created these threats, they have the ability to reduce them," Dr Rachel Bronson. President and CEO of Bulletin of the Atomic Scientists said in a press conference.

The announcement was made in English and for the first time in Ukrainian and Russian to make a statement about the danger of the unprovoked Russian war against Ukraine.

Why does the doomsday clock move?

The clock as a warning symbol for humanity’s ability to destroy itself was put forward in 1947. There at the beginning of the Atomic Age, it became clear that an atomic war between the US and the USSR could wipe us out. Research has shown that even a small-scale atomic war could kill tens of millions in a few hours and then five billion people would die from the subsequent famine. Back at the start, the clock was seven minutes to midnight.

Every year, the members of the Bulletin of the Atomic Scientists set out to answer two questions: is humanity safer than last year, and is humanity safer than it has been over the last 76 years from human-made threats? And the answers to both those questions have determined 2023’s position.

The furthest the doomsday clock has been from midnight was 17 minutes, achieved in 1991 following the easing of the tension between the former Soviet Union and the United States. Crucial to this was the reunification of Germany and the signing of the first Strategic Arms Reduction Treaty.

The State Of The World In 2022

Russia’s invasion of Ukraine and the risk of destruction of its civil nuclear facilities as well as the threat of deployment of a nuclear bomb were certainly crucial factors in the decision. This has led to an arms-stockpiling both in Europe and Asia. 

But the last year was also a year of inaction when it came to both climate change and the pandemic. The failure of strong commitments from COP 27 and more waves of COVID-19 which have been left to run rampant, show governments continue to fail to plan for a safer future. 

The fact that major emitters of greenhouse gases have done little to curb emissions and that disruptive technologies, both bioweapons and cyber-warfare, the latter of which has led to a proliferation of misinformation, have little regulation were major considerations in the shift in timing.

After 76 years of warning, you may hope that governments might be more cautious about the danger of nuclear war, but this is not the case. So scientists have to continue to cover the stockpiling of nuclear weapons, which are now found in even more countries than ever before. There are over 13,000 nuclear warheads out in the world. The timing shows that humanity's risks of self-annihilation have never been greater but it is also a reminder. It does not have to be this way, and a better and safer world is possible.

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A large iceberg "the size of Greater London" has broken off the Brunt Ice Shelf in Antarctica. The calving event on January 22 is believed to be fully natural and a long time coming. The British Antarctic Survey (BAS) has been documenting the crack for decades, and in 2016 even made the decision to pick up and move their research base 23 kilometers (14 miles) further inland to avoid danger, a wise move as it has now snapped off. 

The Brunt Ice Shelf is 150 meters ( 492 feet) thick and the iceberg that calved from it has a surface area of 1,550 square kilometers (598 square miles). That it’s bigger than the area of cities like New York and Los Angeles, and only slightly smaller than London. The crack that caused the rupture was called Chasm-1, which became active again in 2012 after being dormant for 35 years.

After it began to widen over the following years, in 2016 the BAS decided to shift the Halley base 23 kilometers (14.3 miles) inland by basically putting it on skis and being towed by a tractor. The call to move it was indeed correct as now Chasm-1 has cut off the portion of the Ice Shelf the Halley VI research laboratory used to occupy.

“Our glaciologists and operations teams have been anticipating this event. Measurements of the ice shelf are carried out multiple times a day using an automated network of high-precision GPS instruments that surround the station," Professor Dame Jane Francis, Director of BAS said in a statement.

"These measure how the ice shelf is deforming and moving, and are compared to satellite images from ESA, NASA and the German satellite TerraSAR-X. All data are sent back to Cambridge for analysis, so we know what is happening even in the Antarctic winter – when there are no staff on the station, it is dark for 24 hours and the temperature falls below minus 50 degrees C (or -58F).”

Calving events happen regularly although predicting the exact moment is not possible. Brunt seems to be less affected than the Larsen C Ice Shelf when it comes to the climate crisis and the team doesn’t believe that it played a significant role in this event.

“This calving event has been expected and is part of the natural behaviour of the Brunt Ice Shelf. It is not linked to climate change. Our science and operational teams continue to monitor the ice shelf in real-time to ensure it is safe, and to maintain the delivery of the science we undertake at Halley,” Professor Dominic Hodgson, BAS glaciologist, added.

The iceberg will be given an official name by the U.S. National Ice Center.

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As egg prices soar, the deadliest bird flu outbreak in US history drags on

SpaceX on Tuesday confirmed that it fully fueled its Starship launch system during a critical test on Monday and is now preparing to take the next step toward launch.

 

The company shared images and video of its fully fueled Starship upper stage and Super Heavy first stage in South Texas. The shiny, stainless steel vehicles appeared frosty as they were loaded with super-cold liquid oxygen and methane propellants.

 

During this "wet-dress rehearsal" test, SpaceX said it loaded more than 10 million pounds (about 4.6 million kg) of propellant onboard the vehicle, which, when fully stacked, stands 120 meters tall. Essentially then, over the course of a little more than an hour, the company filled a skinny, 30-story skyscraper with combustible liquid propellants—and nothing blew up.

 

Notably, SpaceX completed this important fueling test on its first attempt with Starship and Super Heavy in a stacked configuration, testing both the rocket as well as the launch tower and myriad ground systems required to pump all of these pressurized cryogenic fluids.

 

Now, SpaceX said, the company's engineers and technicians will remove the Starship vehicle from atop the first stage and set it aside. This will enable the company to conduct a static fire test of all 33 Raptor 2 rocket engines presently attached to the first stage. This is the final major technical test before a launch attempt can take place.

 

This firing will test several key systems, including engine ignition and the plumbing inside the rocket to carry all that fuel to all those engines simultaneously. It is possible that this test could occur within the next week or 10 days, but that timeline likely depends on a lot of work being done on schedule.

 

And if that test goes well? SpaceX will share the data from this and other tests with the Federal Aviation Administration, which is responsible for licensing the experimental launch from SpaceX's facilities in South Texas. In addition, SpaceX also has work to do to prepare its ground systems in South Texas for the launch attempt.

 

Nevertheless, it is clear that SpaceX is making excellent progress toward the much-anticipated liftoff of Starship, which will be the heaviest, tallest, most capable, and most powerful rocket to ever take off from Earth.

 

SpaceX completes fueling test, will now work toward massive engine firing test

On Monday, a nationwide blackout in Pakistan left millions of people in the darkness, and the authorities are investigating if it was caused by a cyberattack. The power outage impacted all the major cities in Pakistan.

The good news is that authorities were able to restore power across Pakistan within 24 hours.

“Pakistan‘s energy minister said on Tuesday there was a “remote chance” that hackers could be behind a grid failure that led to two days of nationwide blackout.” reported the Independent. “Khurram Dastgir told the media that the country’s power supply has been restored.”

Cyber attacks against critical infrastructure, such as power grids, are very dangerous. Some of the most clamorous attacks clamorous attacks observed in the past hit Ukraine in 2015 and 2016.

Prime Minister Shehbaz Sharif established a pool tacked on the investigation into the incident.

On behalf of my government, I would like to express my sincere regrets for the inconvenience our citizens suffered due to power outage yesterday. On my orders an inquiry is underway to determine reasons of the power failure. Responsibility will be fixed.

— Shehbaz Sharif (@CMShehbaz) January 24, 2023

The energy minister worned of other “power outages” that could happen in the next days, because nuclear and coal power plants in the country are still facing problems and are not yet fully recovered.

According to the media, some power generation units had been intentionally and temporarily turned off on Sunday night to save energy expenditure, a common procedure in the winter, but operators were not able to to turn on again them on Monday morning. The investigators have to shed light on the problems that occurred on Monday morning.

“When the systems were turned on at 7:30am one by one, frequency variation was reported in the southern part of the country between Jamshoro and Dadu. There was a fluctuation in voltage and power generating units were shut down one by one due to cascading impact,” Dastgir Khan explained.

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Alex Wiltschko opens a black plastic suitcase and pulls out about 60 glass vials. Each contains a different scent. One smells starchy with soft floral notes, like jasmine rice cooking. Another brings to mind ocean air and the white rind of a watermelon. One is like saffron with hints of leather and black tea. The next is the pungent aroma of fig leaves, boxwood, and basil. The most surprising one has the tang of a Thai chili pepper without the nostril-burning heat. 

The molecules wafting into my nose are nothing like I’ve ever smelled before. In fact, I’m one of only a handful of people who have ever smelled them. And yet, before any person had sniffed them, a computer model predicted how they’d smell to us. 

Wiltschko has been obsessed with scents since he was a teenager, and for the past several years he has been developing software at Google Research to predict the scent of molecules based on their structure alone. The vials he’s invited me to smell are the basis of his new startup, Osmo, a spinout of Google Research based in Cambridge, Massachusetts. With $60 million in an initial funding round led by New York-based Lux Capital and GV (Google Ventures), Osmo aims to create the next generation of aroma molecules for perfumes, shampoos, lotions, candles, and other everyday products. 

The $30 billion global fragrance industry relies on raw ingredients that are becoming increasingly difficult or controversial to source. Supplies of flowers popular in perfumery are dwindling because of extreme weather driven by climate change. Species like sandalwood trees are endangered from overharvesting. Other ingredients, like saffron or vetiver, are vulnerable to supply chain disruptions due to geopolitical turmoil. Some brands still use musk and other odors sourced from animals, which presents ethical issues, since it means they must be captured or killed. Meanwhile, some synthetic alternatives, such as lilial, which smells like lily of the valley, are facing regulatory bans for safety reasons. 

Chemists at fragrance companies have figured out how to replicate some natural aromas, but it’s still a largely manual process, and many scents don’t have synthetic substitutes. “We need to be building replacements. Otherwise, we're going to have to continue to harvest these plants and animals from our ecosystem,” says Wiltschko, cofounder and CEO of Osmo, who headed the digital olfaction team while he was at Google Research. “There's a huge opportunity to build safe and sustainable and renewable ingredients that don't require that we harvest life.”

In the near term, the company wants to design molecules for the flavor and fragrance industry that are potent, allergen-free, and biodegradable. “We see Osmo as a rational design business model where people want a very specific odor and we design the chemicals, just like you would design a drug in a biotech or pharma company and then be able to license those,” says Josh Wolfe, a managing partner at Lux Capital and cofounder of Osmo. In the long term, the company wants to give computers a sense of smell—to “digitize” scent—although that concept is less far along and faces some uphill technical challenges.

The olfactory system isn’t as well understood as our other senses, but that’s because it’s arguably more complex, says Joel Mainland, an olfactory neuroscientist at the Monell Chemical Senses Center in Philadelphia who collaborated with Wiltschko’s olfaction team at Google Research but isn’t involved in Osmo. 

The ability to detect smells—baking bread, grass after rain, cigarette smoke, or your grandmother’s perfume—starts when these scent molecules float through the air, enter your nose, and bind to odor receptors, which relay information to the brain through the olfactory nerve. The human nose has about 400 types of receptors, or special sensor proteins. By comparison, the eye uses three types to produce vision, and we taste with about 40 kinds of receptors. 

That complexity makes it harder to categorize scents than other perceptual experiences. colour can be represented with a gradient known as a colour wheel, and sounds by the frequency of their waves. Nothing similar exists for odors. “Right now, we need some way to understand how odors are related to each other,” Mainland says. “We don't have a good way to organize smells.” 

So Wiltschko’s Google team worked to build what they call an “odor map”—a way of categorizing scents so molecules that smell alike are clustered together. But instead of relying on human noses to make these distinctions, they used artificial intelligence. 

They began by feeding machine-learning software a data set of 5,000 scent molecules available from fragrance catalogs—all odors that have been commonly used and are well described. For example, is the scent fruity, buttery, woody? From this training set, the software began to note associations between the chemical structure of each odor molecule and how a human would describe it, building out a high-dimensional map of odors that grouped molecules based on these characteristics. “It sounds like a simple problem, but little tiny changes in a molecule's structure can move it from smelling like roses to rotten eggs,” Wiltschko says. For instance, the chemical bonds or number of carbon atoms in a molecule can affect its odor. 

Then they gave the software a more mysterious data set to parse: 400 molecules that had been designed by scientists but never produced, so their odors remained undescribed. They asked the model to predict what each molecule would smell like to people—based solely on its structure.

To test how well these predictions stacked up, Mainland and his colleagues at Monell asked a panel of 15 volunteers to sniff each odor and assign it labels: floral, minty, smoky, and so on. The panelists didn’t always agree with each other; olfaction is more subjective than many other senses. But for 53 percent of the scents, the model’s predictions were closer to the panel average than to any one volunteer. 

The team considered that a success, although the system has some limitations, says Wiltschko. For instance, two molecules can be mirror images of each other but smell different. “The smells aren't always radically different, but they are subtly different, and our neural network is completely blind to that,” he says. 

The team posted its findings to the preprint server bioRxiv in September, and the paper is currently being peer-reviewed at a scientific journal.

“One thing we want to do in olfactory science is understand how it is that humans perceive odors,” says Krishnan Padmanabhan, an olfactory neuroscientist at the University of Rochester School of Medicine who isn’t involved in Osmo. He says the group’s odor map points to a way to do that. “It’s really striking what they were able to accomplish.” 

The glass vials Wiltschko had me smell contained the same scents those Monell panelists had sniffed. He says Osmo is in active talks with several fragrance companies to license some of them.

Some novel scents are more commercially viable than others, says Christophe Laudamiel, a French master perfumer who serves as an adviser to the company, and who guided me over Zoom as I smelled the different odors. (There are just 600 perfumers in the world, according to New York-based International Flavors & Fragrances, one of the major companies that concocts new scents.) For example, there are very few molecules available that smell like the ocean, Laudamiel says, so a new sea scent would be highly desirable. He’s not sure how the fragrance industry would use the chili pepper one, but he could see it being used for food flavoring. 

“The industry is very small, and there are only a few companies that have embarked on finding new molecules,” he says. “It takes a lot of serendipity to find a new molecule with a new scent.” 

And the failure rate is high. Not only do those molecules have to smell good, they also have to be safe and biodegradable. Companies might test a thousand molecules a year just to bring a few to market that check all these boxes. When Wiltschko sent him the molecules Osmo had created, Laudamiel said: “You realize you've created an alternate universe of perfume ingredients.”

There is another problem Wiltschko thinks Osmo’s technology can solve: creating a better mosquito repellent.

 Mosquito-borne diseases like malaria and dengue fever are responsible for more than 700,000 deaths annually, according to the World Health Organization. Female mosquitoes feed on human blood and are attracted to the smell of skin. Most chemical repellents, including DEET, which is considered the gold standard, work by confusing mosquitoes’ olfactory signals, preventing them from finding their next target. 

But DEET has some drawbacks. It has to be used at high concentrations, it can degrade plastic, and it can cause skin irritation. It’s also possible that mosquitoes could develop resistance to DEET, as they have to other chemicals, says Chris Potter, a neuroscientist at Johns Hopkins who studies the mosquito olfactory system. “I think there is a good reason to look for additional repellents,” says Potter, who isn’t involved with Osmo. “We always need to have a backup.”

In 2020, the Environmental Protection Agency approved the first new repellent in 11 years—a naturally occurring chemical called nootkatone, which gives grapefruit its characteristic scent. But Wiltschko and his team at Google thought they could use their machine-learning system to find new ones. 

First, they needed a large data set of scent molecules so they could train their model to recognize the correlations between a compound’s structure and its effectiveness as a repellent. But they could only find a few dozen mosquito repellents described in recent scientific literature. So Wiltschko tracked down a US government report from the 1940s, when scientists tested around 19,000 compounds for their effectiveness. That effort ranked these compounds according to how well they worked and led to the discovery of DEET. Wiltschko and his team digitized the data set, then trained their algorithms on it.

As they had in the fragrance experiment, they provided their model with 400 novel molecules that had not been tested for their repellency. In this case, they asked the model to predict which would work, based only on each one’s chemical structure. From these, they chose 317 for screening with a standard lab test. It showed that more than 10 of them had a repellency similar to or greater than DEET and other chemicals currently in use. 

The team published its findings in a preprint on bioRxiv, but the paper has not yet been peer-reviewed. Next, Wiltschko says Osmo plans to test those molecules for skin safety and biodegradability. 

Potter is impressed with the team’s method. “It unleashed this data that we've been sitting on for so long,” he says. “Now we have this great list to work from. It’s worth taking a closer look at these chemicals.” 

Wiltschko and Wolfe see bespoke scent molecules and new repellents as just the beginning—they’re on a mission to give computers a sense of smell. They think AI can get us closer to digital olfaction by predicting what odors smell like and how they relate to other scents. “The long-term vision is ‘Shazam’ for smell,” as Wolfe puts it. Just as you can use an app to identify the song that’s playing on the radio, Wolfe thinks you should be able to capture, save, and transmit scents with your phone. 

But that’s a difficult problem. While a phone is built to transmit sound, it’s not built to transmit chemicals. Such a device would have to collect scent molecules, convert them into a digital signature, and pass the signal to someone else’s phone or computer where it would be decoded. Then they’d need some kind of chemical-releasing device to convert that signal back into an inhalable scent.  

And Osmo hasn’t yet given specifics about how it would approach digitizing smell, although Wiltschko has laid out the basic idea. “You need three parts: a sensor, a map, and a printer. The sensor takes the physical world and converts atoms to bits. The map helps you interpret, store, compress, and transmit the bits. In colour, these are technologies like RGB and JPEG. Then, you need to be able to turn the bits back to atoms,” Wiltschko says. “We think the time is now to begin putting these all together.”

The company hasn’t built any sensors yet for capturing smells into digital signals—or devices to “print” smells, for that matter—but Wiltschko says they are collaborating with outside researchers to do so. Wiltschko calls the problem “ridiculously hard” and says it will take years. 

In fact, people have been trying for decades. DigiScents iSmell, a USB-connected cartridge for desktop computers, launched in 1999. It was supposed to encode and then play back scent data collected online, and WIRED claimed it would “launch the next Web revolution.” But the company shut down in 2001 due to a lack of funding. 

In 2014, Vapor Communications launched the oPhone, a device that connected to an iPhone or iPad to allow users to send scents with messages. In 2016, the company also introduced a “scent speaker” called Cyrano that allowed people to play sequences of scents, like a playlist for odors. Neither of those products is still on the market.

Most recently, tech startup Feelreal tried to incorporate scent into a virtual reality headset, but it ran into a regulatory snag with the Food and Drug Administration because the agency considered it a vaping product. The headset has yet to make it to consumers.

Why try to digitize smell at all? For Wiltschko and Wolfe, it’s because smells have the exceptional ability to trigger memories. “We have not been able to capture what is arguably evolutionarily our most salient sense, which is our sense of smell,” Wolfe says. “We evolved that sense to be able to ward off danger, detect loved ones, smell rotting food, and enjoy the beauty of the world, and those are difficult things to share with people unless somebody else is there.”

For now, they will start with trying to shake up the fragrance industry by recreating existing scents and unearthing new ones. As Wiltschko puts the scent vials back into the suitcase, I consider whether I’d want to wear any of the Osmo scents I sampled. One was rose with hyacinth and fresh greenery. My usual perfume, a rose scent made by a French brand, has been steadily increasing in price, and its aroma has changed over the years. Once, when I was in the store, I asked why: The issue was the rose supply chain.

Perhaps if I could find an alternative, I’d switch. 

This Startup Is Using AI to Unearth New Smells

(May require free registration to view)

European launch chief insists there be no competition with Ariane rockets

Rocket Lab set to try its first US-based launch again

Britain’s Crown Estate, an independent commercial business that manages the property portfolio belonging to the British monarch, filed a case against the social media giant over alleged unpaid rent at its London offices.

Court lists showed the case against Twitter was filed at the High Court in London last week.

The Crown Estate, which is owned by King Charles and administers thousands of acres of Crown-owned land across the U.K., confirmed the action related to “rental arrears” over its premises at 20 Air Street, London.

The 260-year-old company is one of the U.K.’s largest landowners—including 10 million square feet of property in London’s West End alone.

Profits from the collection of land and buildings are collected by the British government, with $3 billion generated for public spending in the last 10 years.

Since taking over Twitter last year, Elon Musk has been slashing costs, including cutting at least $1 billion in IT spending, auctioning surplus office furniture, and laying off more than half the workforce.

Reports suggest that the tech giant’s London office near Piccadilly Circus has been deserted for some months, with Twitter signage and logos removed.

This isn’t the first time Musk’s company has gotten in trouble for being behind on rent

The British court case comes alongside similar trouble in the U.S., where Twitter failed to pay almost $6.8 million rent on its San Francisco headquarters in December and January, according to a lawsuit filed by the landlord.

Sri Nine Market Square drew $3.6 million from Twitter’s security deposit to satisfy the payment missed in December, but Twitter still owes $3.1 million in unpaid rent from January.

Twitter leases over 460,000 square feet of space across eight floors in the San Francisco building, according to the complaint.

The landlord is also seeking to increase Twitter’s letter of credit to $10 million, based on a clause in its lease triggered by the transfer of control of the company, but said Twitter has refused to do so.

Meanwhile, earlier this month another San Francisco landlord accused Elon Musk’s company of not paying rent.

The owner of 650 California St.—Columbia REIT, an affiliate of Columbia Property Trust—accused the tech giant of dodging $136,260 in rent payments for use of the 30th floor, according to the lawsuit.

Nonpayment has been reported as part of Musk’s overall business strategy to keep costs down. So far the approach has gone from skipping rent to refusing to pay for jet flights taken.

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The new timing of the clock set by the Bulletin of the Atomic Scientists is closer to midnight than ever before.

The hands of the clock, which the Bulletin describes as a "metaphor for how close humanity is to self-annihilation," had been at 100 seconds to midnight since January 2020 -- the closest to midnight it had been in its history.

A decision to reset the hands of the symbolic timepiece is taken each year by the Bulletin's science and security board and its board of sponsors, which includes 10 Nobel laureates.

In a statement, the Bulletin said it was advancing the hands of the clock by 10 seconds this year "due largely but not exclusively to Russia's invasion of Ukraine and the increased risk of nuclear escalation."

"Russia's thinly veiled threats to use nuclear weapons remind the world that escalation of the conflict -- by accident, intention, or miscalculation -- is a terrible risk," it said. "The possibility that the conflict could spin out of anyone's control remains high."

The Bulletin said the new clock time "was also influenced by continuing threats posed by the climate crisis and the breakdown of global norms and institutions needed to mitigate risks associated with advancing technologies and biological threats such as Covid-19."

"We are living in a time of unprecedented danger, and the Doomsday Clock time reflects that reality," said Rachel Bronson, president and CEO of the Bulletin of the Atomic Scientists.

"90 seconds to midnight is the closest the clock has ever been set to midnight, and it's a decision our experts do not take lightly," Bronson said.

"The US government, its NATO allies and Ukraine have a multitude of channels for dialogue," she said. "We urge leaders to explore all of them to their fullest ability to turn back the clock."

- Calls for action -

Former UN secretary-general Ban Ki-moon also called for world leaders to take action in a world that has become more dangerous because of Covid-19, extreme weather events and "Russia's outrageous war on Ukraine."

"Leaders did not heed the Doomsday Clock’s warnings in 2020," Ban said. "We all continue to pay the price. In 2023 it is vital for all our sakes that they act."

The Nobel Peace Prize-winning International Campaign to Abolish Nuclear Weapons also noted the shift in the clock's hands.

"We have had enough of the Doomsday Clock warnings being followed by inaction," ICAN executive director Beatrice Fihn said in a statement.

"The leaders of the nuclear armed states must urgently negotiate nuclear disarmament, and the G7 meeting in Hiroshima in May 2023 is the perfect place to outline such plan," Fihn said.

The clock was originally set at seven minutes to midnight.

The furthest from midnight it has ever been is 17 minutes, following the end of the Cold War in 1991.

The Bulletin was founded in 1945 by Albert Einstein, J. Robert Oppenheimer and other scientists who worked on the Manhattan Project which produced the first nuclear weapons.

The idea of the clock symbolizing global vulnerability to catastrophe followed in 1947.

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The Justice Department is seeking the breakup of Google’s business brokering digital advertising across much of the internet, a major expansion of the legal challenges the company faces to its business in the U.S. and abroad.

A lawsuit filed Tuesday, the Justice Department’s second against the Alphabet Inc. GOOG -1.24%decrease; red down pointing triangle

unit following one filed in 2020, alleges that Google abuses its role as one of the largest brokers, suppliers and online auctioneers of ads placed on websites and mobile applications. The filing promises a protracted antitrust battle with wide-ranging implications for the digital-advertising industry.

Filed in federal court in Virginia, the case alleges that Google abuses monopoly power in the ad-tech industry, hurting web publishers and advertisers that try to use competing products.

The lawsuit asks the court to unwind Google’s “anticompetitive acquisitions,” such as its 2008 purchase of ad-serving company DoubleClick, calling for the divestiture of its ad exchange.

“Google uses its dominion over digital advertising technology to funnel more transactions to its own ad tech products where it extracts inflated fees to line its own pockets at the expense of the advertisers and publishers it purportedly serves,” the complaint read.

A Google spokesman said the lawsuit “attempts to pick winners and losers in the highly competitive advertising technology sector.”

“DOJ is doubling down on a flawed argument that would slow innovation, raise advertising fees, and make it harder for thousands of small businesses and publishers to grow,” the spokesman said.

Big tech companies such as Google are under a barrage from lawmakers and regulators across multiple continents who have targeted the companies’ dominance in online markets. Justice Department officials also are investigating Apple Inc. The Federal Trade Commission has sued Meta Platforms Inc.’s Facebook unit over antitrust allegations and Microsoft Corp. to block its planned $75 billion acquisition of Activision Blizzard Inc. President Biden recently urged lawmakers from both parties to unite behind legislation seeking to rein in tech giants. The European Union also has opened cases looking at alleged anticompetitive conduct by Google, Meta and other companies.

The Justice Department’s 2020 lawsuit against Google targeted its position in online search markets, including an agreement to make Google search the default in Apple’s Safari web browser. Google is fighting the case, which is expected to go to trial this year.

Alphabet gets about 80% of its business from advertising. The Justice Department’s new suit targets the subset of that ad business that brokers the buying and selling of ads on other websites and apps. Google reported $31.7 billion in revenue in 2021 from that ad-brokering activity, or about 12% of Alphabet’s total revenue. Google distributes about 70% of that revenue to web publishers and developers.

Last year, Google offered to split off parts of its ad-tech business into a separate company under the Alphabet umbrella to fend off the most recent Justice Department investigation. Justice Department officials rejected the offer and decided to pursue the lawsuit instead.

For years, Google has faced allegations from advertising- and media-industry executives, lawmakers and regulators that its presence at multiple points of the online ad-buying process harms publishers and gives it an unfair advantage over rivals. Google also operates the most popular search engine and the largest online video-streaming site, YouTube, giving rise to allegations it has tilted the market in its own favor.

Rivals say that Google’s power in digital advertising stems from a series of acquisitions Google used to build its ad-tech business, beginning with the company’s $3.1 billion purchase of DoubleClick. The FTC approved the merger in a controversial decision. Google went on to purchase a host of other startups including the mobile-advertising company AdMob.

“Having inserted itself into all aspects of the digital advertising marketplace, Google has used anticompetitive, exclusionary, and unlawful means to eliminate or severely diminish any threat to its dominance over digital advertising technologies,” the complaint read.

Google has said it has no plans to sell or exit the ad-tech business. It has also strongly contested claims in a lawsuit filed by state attorneys general containing allegations similar to the Justice Department complaint. A federal judge denied the bulk of Google’s motion to dismiss the case last year, allowing it to proceed to the discovery stage and ultimately toward trial.

Any judgment against Google in the Justice Department’s new lawsuit likely would cause big ripple effects across the online advertising industry, which has recently shown signs of weakness as consumers dial back purchases in response to worsening economic conditions.

Breaking off some or all of Google’s ad-tech business from the rest of the company could take years of litigation to resolve. Depending on the outcome of the case, ad-tech executives have said the results could range from a higher share of ad dollars flowing to publishers to lower overall spending because digital ads would be less efficient without Google brokering them.

The Justice Department case overlaps in some ways with an investigation that the EU’s top antitrust enforcer, the European Commission, opened in 2021, as well as one by the U.K.’s Competition and Markets Authority. Those probes are exploring allegations that Google favors its own ad-buying tools in the advertising auctions it runs, but also look at other elements of Google’s ad-eurotech business. The EU, for instance, is also looking at Google’s alleged exclusion of competitors from brokering ad-buys on its video site YouTube.

Google has attempted to settle many of these claims. In addition to offering to split off parts of its ad-tech business to avoid the Justice Department suit, the company last year discussed with the EU an offer to allow competitors to broker the sale of ads directly on the video service.

In 2021, the company agreed to give U.K. antitrust regulators effective veto power over elements of its plans to remove a technology called third-party cookies from its Chrome browser to settle an investigation there into the plan.

In France, Google agreed to pay a fine of 220 million euros, equivalent to about $239 million, and to improve data access to competing ad-tech companies, to not use its data in ways rivals couldn’t reproduce to settle a similar antitrust investigation in the country.

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Also:  Justice department sues Google over its ‘unlawful’ online advertising dominance

Scientists identify rare lead compounds in Rembrandt’s The Night Watch

Few would argue right now that physics doesn’t matter, barely a month after scientists at Lawrence Livermore National Laboratory achieved fusion ignition, a breakthrough step toward unlocking a new source of abundant, clean energy. Australian physicist Suzie Sheehy wants to go further, however, making the experimental side of the science accessible and reconnecting us with forgotten pioneers who helped change the ways we understand the world.

She discussed her debut book, “The Matter of Everything: How Curiosity, Physics, and Improbable Experiments Changed the World,” with Greg Kestin, Ph.D. ’14, associate director of science education and a lecturer on physics, in an online event last Wednesday presented by the Division of Science and Harvard Library with Harvard Book Store. Sheehy offered a rapid-fire overview of the history of the science, along with an introduction to some unsung heroes of the field and some peeks into where it may be heading next.

Sheehy, who oversees research groups at the universities of Oxford and Melbourne and currently focuses on medical applications, laid out five basic points. First, she said, “How we know is just as important as what we know.”

For that reason, “I celebrate experiments,” said Sheehy, whose book is organized around 12 key experiments from the last 120 years.

Acknowledging that theoretical physics, practiced by such luminaries as Albert Einstein, may be better known, she described her experimental colleagues as having “a more nuanced job,” requiring “good questions, persistence, and a whole lot of luck.” As an example, she recalled the 1897 experiment into cathode rays that resulted in the discovery of electrons and “gave birth to the entire electronics industry.” Without that, she noted, “rock ’n’ roll would never have happened.”

Her second point — “The results in curiosity-driven research grow in usefulness over time” — was reflected in the 1896 discovery of the X-ray. Not only did it allow doctors to look beneath a patient’s skin, it also gave photographers a new artistic tool and has become crucial to airport security. “New discoveries make new imaginings possible,” she said.

“Science may be objective, but scientists are not,” was her next point. Even great physicists have blind spots, she noted, quoting physicist Albert Michelson, who said in 1894, “It seems probable that most of the grand underlying principles have been firmly established.” This was before the discovery of X-rays, radioactivity, and the electron — and before quantum mechanics would completely upend the field. Sheehy quipped, “It’s hard to predict the future.”

Following up on scientists’ very human failings, Sheehy delivered her fourth point in the form of a question: “Who gets to be a physicist?”

“Curiosity is a human trait,” she said. “It’s not racist or sexist, but we’ve been restricting this field.” To counter the “strong white man” narrative too often championed in her field, Sheehy briefly introduced some of the female physicists featured in her book. These include Harriet Brooks, who helped decipher how radioactive elements change, as well as Marietta Blau, whose work led to a new kind of particle detector, and Bibha Chowdhuri, an Indian particle physicist who researched cosmic rays.

Ultimately, “collaboration is the human force of nature,” said Sheehy, making her final point. Citing “the power of collaboration,” she pointed out the great strides being made at CERN, the European Organization for Nuclear Research. The organization, which has 23 member states, was designed to foster such collaboration — and invented the World Wide Web in order to do so. Currently, the Swiss-based main lab not only brings international teams together, it houses the Large Hadron Collider, allowing for the kind of experiments very few, if any, of the member countries would be able to afford on their own.

Following up Sheehy’s presentation with a discussion that included questions from audience members, Kestin asked about the future of the field.

Sheehy reflected back on Michelson’s remark of more than a century ago, and how easy it is to assume that we’re reaching the end of human knowledge. “It feels like we’re done with physics, and yet we know there’s more,” she said. In particular, she pointed out that even the most recent discoveries, such as those into the nature of subatomic particles like muons, only account for roughly 4 percent of all matter. Much of what else makes up our universe, known as dark matter, remains a mystery.

“It’s exciting to think that over 90 percent of matter is not understood,” said Kestin.

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FOR NOW, ALEX Lagetko is holding on to his Tesla stocks. The founder of hedge fund VSO Capital Management in New York, Lagetko says his stake in the company was worth $46 million in November 2021, when shares in the electric carmaker peaked at $415. 

Since then, they have plunged 72 percent, as investors worry about waning demand, falling production and price cuts in China, labor shortages in Europe, and, of course, the long-term impact of CEO Elon Musk’s $44 billion acquisition of Twitter. After announcing his plans to buy the platform in April, Musk financed his acquisition with $13 billion in loans and $33 billion in cash, roughly $23 billion of which was raised by selling shares in Tesla. 

“Many investors, particularly retail, who invested disproportionately large sums of their wealth largely on the basis of trust in Musk over many years were very quickly burned in the months following the acquisition,” Lagetko says, “particularly in December as he sold more stock, presumably to fund losses at Twitter.”

Lagetko is worried that the leveraged buyout of Twitter has left Tesla exposed, as interest payments on the debt Musk took on to fund the takeover come due at the same time as the social media company’s revenues have slumped.

But Tesla stock was already falling in April 2022, when Musk launched his bid for Twitter, and analysts say that the carmaker’s challenges run deeper than its exposure to the struggling social media platform. Tesla and its CEO have alienated its core customers while its limited designs and high prices make it vulnerable to competition from legacy automakers, who have rushed into the EV market with options that Musk’s company will struggle to match.

Prior to 2020, Tesla was essentially “playing against a B team in a soccer match,” says Matthias Schmidt, an independent analyst in Berlin who tracks electric car sales in Europe. But that changed in 2020, as “the opposition started rolling out some of their A squad players.”

In 2023, Tesla is due to release its long-awaited Cybertruck, a blocky, angular SUV first announced in 2019. It is the first new launch of a consumer vehicle by the company since 2020. A promised two-seater sports car is still years away, and the Models S, X, Y, and 3, once seen as space-age dynamos, are now “long in the tooth,” says Mark Barrott, an automotive analyst at consultancy Plante Moran. Most auto companies refresh their looks every three to five years—Tesla’s Model S is now more than 10 years old.

By contrast, this year Ford plans to boost production of both its F-150 Lighting EV pick-up, already sold out for 2023, and its Mustang Mach-E SUV. Offerings from Hyundai IONIQ 5 and Kia EV6 could threaten Tesla’s Model Y and Model 3 in the $45,000 to $65,000 range. General Motors plans to speed up production and cut costs for a range of EV models, including the Chevy Blazer EV, the Chevy Equinox, the Cadillac Lyric, and the GMC Sierra EV. 

While Tesla’s designs may be eye-catching, their high prices mean that they’re now often competing with luxury brands. 

“There is this kind of nice Bauhaus simplicity to Tesla’s design, but it’s not luxurious,” says David Welch, author of Charging Ahead: GM, Mary Barra, and the Reinvention of an American Icon. “And for people to pay $70,000 to $100,000 for a car, if you’re competing suddenly with an electric Mercedes or BMW, or a Cadillac that finally actually feels like something that should bear the Cadillac name, you’re going to give people something to think about.”

While few manufacturers can compete with Tesla on performance and software (the Tesla Model S goes to 60 mph in 1.99 seconds, reaches a 200-mph top speed, and boasts automatic lane changing and a 17-inch touchscreen for console-grade gaming), many have reached or are approaching a range of 300 miles (480 km), which is the most important consideration for many EV buyers, says Craig Lawrence, a partner and cofounder at the investment group Energy Transition Ventures.

One of Tesla’s main competitive advantages has been its supercharging network. With more than 40,000 proprietary DC fast chargers located on major thoroughfares near shopping centers, coffee shops, and gas stations, their global infrastructure is the largest in the world. Chargers are integrated with the cars’ Autobidder optimization & dispatch software, and, most importantly, they work quickly and reliably, giving a car up to 322 miles of range in 15 minutes. The network contributes to about 12 percent of Tesla sales globally.

“The single biggest hurdle for most people asking ‘Do I go EV or not,’ is how do I refuel it and where,” says Loren McDonald, CEO and lead analyst for the consultancy EVAdoption. “Tesla figured that out early on and made it half of the value proposition.”

But new requirements for funding under public charging infrastructure programs in the US may erode Tesla’s proprietary charging advantage. The US National Electric Vehicle Infrastructure Program will allocate $7.5 billion to fund the development of some 500,000 electric vehicle chargers, but to access funds to build new stations, Tesla will have to open up its network to competitors by including four CCC chargers.

“Unless Tesla opens up their network to different charging standards, they will not get any of that volume,” Barrott says. “And Tesla doesn’t like that.”

In a few years, the US public charging infrastructure may start to look more like Europe’s, where in many countries the Tesla Model 3 uses standard plugs, and Tesla has opened their Supercharging stations to non-Tesla vehicles. 

Tesla does maintain a software edge over competitors, which have looked to third-party technology like Apple’s CarPlay to fill the gap, says Alex Pischalnikov, an auto analyst and principal at the consulting firm Arthur D. Little. With over-the-air updates,

Tesla can send new lines of code over cellular networks to resolve mechanical problems and safety features, update console entertainment options, and surprise drivers with new features, such as heated rear seats and the recently released full self-driving beta, available for $15,000. These software updates are also a cash machine for Tesla. But full self-driving features aren’t quite as promised, since drivers still have to remain in effective control of the vehicle, limiting the value of the system.

A Plante Moran analysis shared with WIRED shows Tesla’s share of the North American EV market declining from 70 percent in 2022 to just 31 percent by 2025, as total EV production grows from 777,000 to 2.87 million units.

In Europe, Tesla’s decline is already underway. Schmidt says data from the first 11 months of 2022 shows sales by volume of Volkswagen’s modular electric drive matrix (MEB) vehicles outpaced Tesla’s Model Y and Model 3 by more than 20 percent. His projections show Tesla’s product lines finishing the year with 15 percent of the western European electric vehicle market, down from 33 percent in 2019.

The European Union has proposed legislation to reduce carbon emissions from new cars and vans by 100 percent by 2035, which is likely to bring more competition from European carmakers into the market. 

There is also a growing sense that Musk’s behavior since taking over Twitter has made a challenging situation for Tesla even worse.

Over the past year, Musk has used Twitter to call for the prosecution of former director of the US National Institute of Allergy and Infectious Diseases Anthony Fauci (“My pronouns are Prosecute/Fauci”), take swings at US senator from Vermont Bernie Sanders over government spending and inflation, and placed himself at the center of the free speech debate. He’s lashed out at critics, challenging, among other things, the size of their testicles. 

A November analysis of the top 100 global brands by the New York–based consultancy Interbrand estimated Tesla’s brand value in 2022 at $48 billion, up 32 percent from 2021 but well short of its 183 percent growth between 2020 and 2021. The report, based on qualitative data from 1,000 industry consultants and sentiment analysis of published sources, showed brand strength declining, particularly in “trust, distinctiveness and an understanding of the needs of their customers.”

“I think [Musk’s] core is rapidly moving away from him, and people are just starting to say, ‘I don’t like the smell of Tesla; I don’t want to be associated with that,’” says Daniel Binns, global chief growth officer at Interbrand.

Among them are once-loyal customers. Alan Saldich, a semi-retired tech CMO who lives in Idaho, put a deposit down on a Model S in 2011, before the cars were even on the road, after seeing a bodiless chassis in a Menlo Park showroom. His car, delivered in 2012, was number 2799, one of the first 3,000 made.

He benefited from the company’s good, if idiosyncratic, customer service. When, on Christmas morning 2012, the car wouldn’t start, he emailed Musk directly seeking a remedy. Musk responded just 24 minutes later: “...Will see if we can diagnose and fix remotely. Sorry about this. Hope you otherwise have a good Christmas.”

On New Year’s Day, Joost de Vries, then vice president of worldwide service at Tesla, and an assistant showed up at Saldich’s house with a trailer, loaded the car onto a flatbed, and hauled it to Tesla’s plant in Fremont, California, to be repaired. Saldich and his family later even got a tour of the factory. But since then, he’s cooled on the company. In 2019, he sold his Model S, and now drives a Mini Electric. He’s irritated in particular, he says, by Musk’s verbal attacks on government programs and regulation, particularly as Tesla has benefited from states and federal EV tax credits.

“Personally, I probably wouldn’t buy another Tesla,” he says. “A, because there’s so many alternatives and B, I just don’t like [Musk] anymore.”

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Hao Huang and Kaiyin He, both from The First Affiliated Hospital at Jinan University in Guangzhou, China, examined the association between dietary fiber intake and the prevalence of severe headache or migraine using data from the National Health and Nutrition Examination Survey (1999 to 2004).

The researchers found that after adjusting for covariates, there was a significant inverse association seen between dietary fiber intake and severe headache or migraine, with the lowest prevalence observed in the fifth quintile (odds ratio, 0.74). For every 10-g/day increase in dietary fiber intake, the prevalence of severe headache or migraine decreased by 11 percent. However, among Mexican Americans, other races, or those with a body mass index of 25 to 30 kg/m², no such inverse association was seen.

"To the best of our knowledge, no previous study has examined the relationship between dietary fiber and severe headache or migraine," the authors write. "Increasing the intake of fiber-rich foods might protect from severe headache or migraine. However, more prospective studies should be conducted to confirm their association."

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Also, what happens if you're a chronic binge eater? Image Credit: Dean Drobot/Shutterstock.com

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Inside the Great Pyramid Of Giza, there is a massive void. The room, sealed when the pyramid was completed some 4,500 years ago, is of unknown purpose, though some have speculated it could be a secret burial chamber of the pharaoh Khufu, who ordered the pyramid to be built. 

In 2017, a team known as ScanPyramids scanned the Great Pyramid of Giza using muon tomography. Muon particles are negatively-charged particles produced by cosmic rays which collide with atoms in the Earth's upper atmosphere at around 10,000 per square meter per minute. 

"Like X-rays, which can penetrate the body and allow bone imaging, these elementary particles can keep a quasi-linear trajectory while going through hundreds of metres of stone before decaying or being absorbed," the team explains in their study, published in Nature. "By recording the position and the direction of each muon that traverses its detection surface, a muon detector can distinguish cavities from stone."

All that is to say that they used a very cool way – involving cosmic rays, no less – to look inside the Great Pyramid. And inside, they found a chamber that had never been seen before.

"We report the discovery of a large void (with a cross-section similar to that of the Grand Gallery and a minimum length of 30 metres [98 feet]) situated above the Grand Gallery," the team wrote. "This constitutes the first major inner structure found in the Great Pyramid since the nineteenth century."

They named the big void, rather aptly, the "big void", and it was confirmed using three different muon detection techniques. So far, it is not known what the void was for, though there have been suggestions. Kate Spence, archaeologist at the University of Cambridge, told National Geographic that the void could be a result of how the pyramid was constructed, an internal ramp used to move roof blocks into position, which was then left or filled loosely with rubble.

Another theory as to the room's purpose is that it was a secret burial chamber of Khufu. When the pyramids were first opened and explored, 19th-century archaeologists found a number of chambers, including one containing a sarcophagus that was thought to contain Khufu himself. However, when the sarcophagus was opened, it was empty. 

The remains have long been, and continue to be, presumed to be stolen. However, the theory that there was a secret fourth chamber that contains the mummy of Khufu predates the discovery of the fourth chamber. In 2004, two amateur French Egyptologists, who used ground-penetrating radar and architectural analysis to back up their claims, came up with a theory that there was an extra chamber.

The two argued that the pyramid wasn't meticulously planned ahead, as believed by most, but evolved as construction went on. Gilles Dormion, the architect of the pair, suggested that the pyramid was adjusted as the builders realized certain chambers would not take the weight of the burial sarcophagus. Giant granite beams are present in the king's chamber, with large cracks in them that have been attributed to earthquakes since the pyramid was built. However, he believes that the cracks happened during the building of the pyramids, as evidenced by traces of ancient plaster found within them. 

"At the end of the day," Dormion said of the theory in 2004, "the entire problem of the Great Pyramid can be summed up by this theory: Khufu had three funeral chambers built for himself. The first remained unfinished, the second was available and the third cracked. Khufu was therefore interred in the second."

The amateurs thought that the chamber where Khufu was interred extended from a hidden corridor from the queen's chamber (a misnomer, as the chamber was likely used as a gift chamber for Khufu), fairly far away from where the big void was subsequently discovered; however, until we get a better look at the void itself it's perhaps a little too optimistic to assume it is a hidden burial chamber for the king, rather than a ramp used in the pyramid's construction. Thankfully, a closer look could be on the way.

In 2022, a team announced their plans to image the pyramid using more sophisticated equipment.

"We plan to field a telescope system that has upwards of 100 times the sensitivity of the equipment that has recently been used at the Great Pyramid," the team writes, "will image muons from nearly all angles and will, for the first time, produce a true tomographic image of such a large structure."

The team explained that once they have funding, it will take around two years to build the detectors.

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Until December 2022, China had used lockdown policies to reduce the opportunity for COVID spread in the hope of eliminating the virus or building up enough population immunity through vaccination. The exceptionally strict zero-COVID policy was very successful in stopping the virus' spread while the world faced returning deadly waves.

However, the prolonged lockdowns eventually became politically and economically unsustainable. China's official policy is currently concentrating on strengthening the early detection and treatment of severe cases rather than the prevention of infections. This has led to claims the country is now pursuing a "herd immunity" approach.

But would this be a realistic goal? Lessons from other countries' experiences suggest not. Let's take a look at why.

Herd immunity: A recap

The herd immunity concept was introduced some 100 years ago to explain why epidemic waves often stop before affecting the whole population.

As a disease such as COVID spreads, more people become infected. Most of them recover and gain infection-induced immunity. Those who become infected increasingly have contact with immune rather than susceptible people. This leads to lower risk of passing on the infection.

The 5% vaccination-induced immunity level, shown here for illustration purposes, reflects the limited booster coverage and the lower efficacy and faster waning of China’s vaccines. Credit: Adam Kleczkowski

The epidemic wave slows down and eventually declines. The decline is caused by a sufficiently large number of people becoming immune, therefore protecting the whole population—or the "herd". In the 1970s, epidemiologists found a simple formula that predicts the proportion of immune individuals at which the number of infections stops growing.

The formula includes the R number, the average number of people one infected person passes the disease onto. Non-pharmaceutical interventions, like social distancing, lockdowns, or mask-wearing, are aimed at reducing the transmissibility of the virus, lowering the value of R.

The herd immunity threshold also depends on the proportion of people with pre-existing immunity from either previous outbreaks or vaccination. Using these concepts, scientists have designed vaccination strategies that successfully keep contagious diseases such as smallpox, polio, diphtheria and rubella under control.

For such public health policies to be successful, mass vaccination needs to reach a high proportion of the population. Sublineages of the omicron variant BA.5 are currently dominant in China. Omicron has an average R of 9.5, so around 90% of the population needs to be fully protected to reach herd immunity, according to the model.

However, vaccination is not perfect. Some 89% of China's population has so far reportedly received two doses of the vaccine. But booster uptake is low and the efficacy of the Sinovac and Sinopharm vaccines used in China is lower than the mRNA vaccines from Pfizer and Moderna used widely. So, the actual percentage of people protected by the vaccine will be lower than in other countries—perhaps as low as 5%.

Before December 2022, China had seen relatively few COVID cases, leaving infection-induced immunity low. This creates a significant gap between the existing levels of immunity and those required to achieve herd immunity, as illustrated in the figure below. In the absence of other control measures, this gap will need to be filled in by infection, resulting in a massive outbreak.

Credit: Institute for Health Metrics and Evaluation, University of Washington and Adam Kleczkowski

Predictions are challenging

Predicting what will happen next in China is difficult due to the lack of reliable data. Although cases now seem to be decreasing, the traditional activity around the lunar new year will most likely cause a new wave.

Several models have explored different assumptions. The Institute for Health Metrics and Evaluation expects almost three million cases per day at an upcoming peak following the lunar new year and 1.6 million deaths by the end of 2023.

Health data analytics company Airfinity predicts four million cases per day at the peak of the upcoming wave, and that the number of deaths could reach 2.1 million. Given the uncertainty about the epidemic spread in China, these numbers might even be underestimates.

Eventually, China's population will temporarily reach the "herd immunity" level, and the upcoming wave will probably peak around March 2023, according to these models. But this is not a guarantee that the epidemic will end there.

The virus persists even in countries like the UK, where roughly 80%–95% of the population have COVID antibodies. This indicates high levels of immunity from prior infection, vaccination, or both.

Unfortunately, the immunity from COVID vaccines and prior infections wanes after some months and may be less durable against new variants. As a result, new waves appear as herd immunity is temporarily breached, before being restored again.

If China is really aiming at herd immunity to eliminate the virus—and some young Chinese people are apparently seeking infection—it will very likely fail again. The repeated lesson from other countries is that the loss of immunity and the appearance of new variants make herd immunity a futile goal when it comes to COVID.

Provided by The Conversation

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11th Hour Racing Team is one of five teams competing in the IMOCA class of this year's Ocean Race, a six-month dash across the world. The IMOCA-class yachts use foils and can reach more than 35 knots.

Amory Ross / 11th Hour Racing

 

Just over a week ago, one of the world's most grueling races got underway off the coast of Africa. Eleven teams, including five International Monohull Open Class Association (IMOCA)-class racing yachts, departed Alicante in the Canary Islands for the first leg of a 32,000-nautical-mile (60,000-km) route that includes a 12,750-nautical-mile stretch between South Africa and Brazil through the Southern Ocean. The crews have little in the way of creature comforts beyond freeze-dried meals and a bucket for a bathroom. Along the way, the boats will collect scientific data on the state of our oceans, from dissolved gases like oxygen and carbon dioxide to microplastics.

 

IMOCA-class boats are 60 feet (18.3 m) long and feature a single hull made from carbon fibre. In addition to sails, the yachts have retractable foils that lift the hull out of the water above 18 knots (33 km/h) and allow a top speed of 35 knots (65 km/h) or more. Designers have some freedom with the hull and sail shape, but everyone has to use the same design of masts, booms, and static rigging.

 

Mālama is one such boat, and it's crewed by the 11th Hour Racing team. In addition to collecting data on climate change, the team worked to minimize the carbon impact of building the yacht itself, experimenting where allowed with lightweight, sustainable materials like balsa or composites made from flax. "I like to think of where can we use renewables that actually adds performance to the program," said Simon Fisher, navigator for the 11th Hour team.

 

"The renewable energy we use on board is a good example of that," Fisher explained, referring to Mālama's solar panels, which charge its 48 V battery and save a lot of weight versus the more traditional approach of a diesel generator and its required fuel. "That's a considerable weight saving, and we're always chasing everything down to the last gram," he said.

 

"If you come on board the boat and looked at a lot of the non-structural elements, things like engine covers, which traditionally would be made out of carbon, are now done in flax and bioresins and all that sort of stuff. And we've actually done that in the build process. We took the time to build some samples and compare weights and durability," Fisher said.

 

Much of that is detailed in 11th Hour's sustainable design and build report (PDF), which describes "the amount of detail that went into measuring absolutely everything," Fisher told Ars. "So every element that went into the boat—what it was made from, the energy use, where things are sourced from, all of that—has been incredibly well-documented." As such, the team hopes the data can be useful to the rest of the industry.

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The IMOCA rules require boat-builders to use energy-intensive carbon fibre as the main material thanks to its high strength and light weight. But here and there, 11th Hour found ways to reduce its carbon impact. Reusing carbon fibre molds, for example, saved more than 170 metric tons of CO2 from the boat's footprint. "There's been some really good and actually surprisingly simple lessons that came out of it. One of the biggest savings in carbon footprint we've made is that the whole boat was built on renewable energy. So the boatyard that the boat was built on was on a renewable energy tariff, and that's like half the carbon footprint," Fisher said.

This 32,000-mile Ocean Race has yachts doing research along the way

A fully stacked Starship launch system is seen on January 9, 2023.

SpaceX

 

After months of preparation, SpaceX is now approaching the critical test phase of its launch campaign for the massive Starship vehicle.

 

The company has evacuated nearby residents from the launch site in South Texas, near Boca Chica Beach, during the hours of 8 am CT (14:00 UTC) to 8 pm CT on Monday. If preparatory activities go well, the company will load both the Starship upper stage and Super Heavy booster with cryogenic methane and oxygen later today. The countdown will proceed toward liftoff but end just before the transfer of internal power to the launch vehicle.

 

There will be no engine ignition today. However, the upper stage of this vehicle, Ship 24, previously underwent a successful static fire test of its six Raptor rocket engines on September 8, 2022. The first stage, Booster 7, has seen as many as 14 of its 33 Raptor engines test fired during activity in November.

 

Now these two vehicles are fully stacked on the launch pad ahead of today's critical fueling test. While not as dramatic as a test firing, such "wet dress rehearsals" are essential to demonstrate the safe fueling of so much propellant at once. It is one of the biggest milestones remaining ahead of an orbital launch attempt that could take place in a month or two.

 

Following a successful wet dress rehearsal, SpaceX engineers will assess the data, and if it looks good, the plan will likely proceed toward the final major pre-flight test. To prepare for this full static firing of all 33 Raptor engines on Booster 7, SpaceX will first remove the Starship upper stage as a precaution in case something were to go awry during testing.

 

Once the static fire test is completed—which may require multiple attempts, given the unprecedented number of large rocket engines firing simultaneously—the vehicles would be re-stacked ahead of a launch attempt. This could come as early as March if things proceed well.

 

Of course, things may not go well, and SpaceX may ultimately decide to use newer iterations of Starship hardware for the orbital test flight. Already, the company has moved "Ship 25" to a launch mount for static fire testing in South Texas. Two additional Starships are in various stages of construction, with parts of Ship 28 and Ship 29 also spotted by observers in South Texas. SpaceX has also already performed cryogenic testing on Booster 9 and has nearly completed stacking of Booster 10.

 

It has been a long time since SpaceX launched any rockets from South Texas. Its final prototype, "SN15," took flight for six minutes on May 5, 2021. After flying to an altitude of 10 km, this was the first prototype to achieve a soft landing, demonstrating key technology for the Starship design.

 

Since that time, SpaceX has invested heavily—likely on the order of $1 billion to $2 billion—in launch infrastructure and production facilities at the Starbase site in South Texas. Although it was willing to take risks with the Starship prototypes, the full stack of Super Heavy and Starship carries substantially more propellant, and an accident at the launch site would be highly destructive.

 

Therefore, SpaceX is proceeding more cautiously toward its orbital test flight. The goal is to ensure the rocket clears the launch site so that it does not damage valuable infrastructure there, at a minimum. Monday's methodical wet dress rehearsal is a key part of that test campaign.

 

While SpaceX is not providing a livestream of Monday's testing, several private streamers, including NASASpaceflight and LabPadre, will have you covered as the rocket turns white and frosty.

 

SpaceX may perform a wet dress rehearsal of its Starship launch system today

Disrupting Earth’s chemical cycles brings trouble. But planet-warming carbon dioxide isn’t the only element whose cycle we’ve turned wonky—we’ve got a phosphorus problem too. And it’s a big one, because we depend on this element to grow the world’s crops. “I don't know if it would be possible to have a full world without any mineral phosphorus fertilizer,” says Joséphine Demay, a PhD student at INRAE, France’s National Research Institute for Agriculture, Food and the Environment.

Since the 1800s, agriculturalists have known that elemental phosphorus is a crucial fertilizer. Nations quickly began mining caches of “phosphate rock,” minerals rich in the element. By the middle of the 20th century, companies had industrialized chemical processes to turn it into a form suitable for supercharging crops, hardening them against disease and making them able to support more people and livestock. That approach worked remarkably well: The post-World War II “Green Revolution” fed countless people thanks to fertilizers and pesticides. But sometimes there’s too much of a good thing.

We have liberated Earth’s caches of phosphorus so rapidly that the element now pollutes freshwater ecosystems, where excesses cause harmful algal blooms, infiltrates the snowpack, and decreases levels of dissolved oxygen in lakes and rivers. Studies suggest that humanity has grown too dependent on it for feeding the planet—and we are running out of this nonrenewable resource, which comes from geologic deposits that take millenia to form. When it washes from soil into waterways, it essentially disappears forever. A looming “peak phosphorus” moment threatens to increase prices and foment political tension if demand eclipses supply, as a large majority of reserves exist only in one corner of North Africa.

In a paper published this month in Nature Geoscience, Demay broke down how much phosphorus 176 countries have used between the years 1950 and 2017, and she estimated how much the use of mineral fertilizer contributes to soil fertility in each nation. Remarkably, phosphate rock accounts for around 50 percent of the world’s soil productivity. “It has never been quantified like that,” Demay says. And those numbers matter, she says, because “the work really highlights the high gap that exists between different world regions.” Wealthy countries in Western Europe, North America, and Asia use far more of the world’s phosphate rock than Africa, despite African soils being relatively deficient in it. “There is a need to distribute more equally the remaining first rock reserves,” Demay says.

James Elser, an ecologist with Arizona State University and the University of Montana who studies the global phosphorus cycle, was taken aback by that 50 percent figure. “That we've been able to mobilize phosphorus from these ancient geological deposits, and spread it around the world enough so that half of soil phosphorus is now comprised of industrial anthropogenic fertilizer, is pretty stunning,” he says.

And if the remaining supply goes down, prices will go up, exacerbating the access gap between rich and poor countries, says Dana Cordell, an associate professor and research director of food systems sustainability at the University of Technology Sydney. In 2008, phosphate prices spiked 800 percent due to supply and demand issues, and again 400 percent last year, due to Covid-related disruptions. The new study “shows how our global food system has now become heavily dependent on mined, nonrenewable phosphate rock,” she says. “And even if there is phosphate rock in the ground, it might not be economically viable to access it.”

Scientists have been pointing out the “broken” phosphorus cycle for more than a decade: Humanity has unearthed huge quantities of the element, which winds up in waterways instead of returning to cropland.

The problem comes down to crap. People and livestock eat crops and excrete phosphorus as a result. (A University of Iowa researcher calculated that the state’s livestock produce a load of excrement equivalent to a nation of 168 million people.) But most of it won’t end up feeding plants again. Waste treatment can loop sludge or manure back to being fertilizer, but transporting and treating it is often impractical, so it may sit in stockpiles and “dry stacks” without the chance to boost another crop.

Or the system may be leaky: Sewage, septic tanks, stockpiles, and eroded soil drip phosphorus into oceans and rivers, where it dilutes to oblivion while degrading those ecosystems. For instance, phosphorus runoff drives the harmful algal blooms that have killed Florida’s seagrass, starving thousands of manatees.

Demay’s model determined that in a 67-year span, humans pumped almost a billion tons of nonrenewable phosphorus into food systems. Her team’s figures are derived from statistical data from the Food and Agriculture Organization of the United Nations. The global data, broken up by country, reported agricultural yields—like the amount of wheat grown, or headcounts of pigs and cows—from 1961 to 2017. (Data from 1950 to 1961 came from other data sets.)

Her team also broke down use trends. In 2017, Western European, North American, and Asian reliance climbed to nearly 60 percent of the total plant-ready phosphorus available in each region’s soil. Brazil, China, and India are quickly increasing their use, to 61, 74, and 67 percent respectively. The numbers for France and the Netherlands are no longer rising, because they’ve replaced some use of phosphate rock with manure; now they sit at roughly 70 and 50 percent. Yet in African countries like Zimbabwe, a lack of soil phosphorus limits crop yields. Demay's estimates pin mineral fertilizer use in Zimbabwe to the 20 to 30 percent range, which is even lower than the 32 percent average for all of Africa.

To Elser, this illuminates a global inequity: Poorer countries access far less fertilizer, despite needing it more. And wealthy countries have been able to amass stockpiles from the rock reserves for decades, while countries that struggle with food security can’t afford to do the same.

This raises concerns over who will control the future of fertilizer. Nearly 75 percent of the world’s supply sits in the mines of Morocco and the Western Sahara. Economists get anxious when a commodity is consolidated in the hands of a few powerful people. (OPEC controls roughly the same fraction of the world’s oil, but with 13 member states.)

And it’s not entirely clear how long supplies will last. In 2009, Cordell estimated that a global “peak phosphorus” moment could happen as soon as 2030, which would leave 50 to 100 years of dwindling reserves. Today, she and Elser agree that the peak will likely come later, although it’s hard to predict when, because demand may skyrocket for other uses, like lithium iron phosphate batteries. Elser notes that new analyses now put the maximum supply at around 300 to 400 years.

To Cordell, it’s frustrating that this supply chain has been mismanaged. “If this was water—or another resource that we know humanity is dependent on—we would have so many measures in place to monitor those resources, to ensure more equitable and secure access,” she says. And if any other crucial resource was running out, she continues, “we would look for alternatives.”

She worries that phosphorus is “slipping through the institutional cracks.” But, she says, it’s not clear who is responsible for overseeing its supply—which government, or even which department. Agriculture? Environment? Health? Water? Trade? “It cuts across all of those sectors,” she says.

Demay hopes that her study will encourage more careful agricultural practices: combining cropland and livestock areas to more easily recycle phosphorus from manure, or planting trees or cover crops, like mustard or barley, that prevent soil erosion in a farm’s off-season—sparing waterways from fertilizer pollution. Better recycling programs might also help ween the world off phosphate rock. Right now, recycling mostly means using manure or sludge from wastewater systems on croplands, which is primarily for preventing water pollution rather than fertilizing plants. “It's happening in such an inefficient, ineffective way,” Cordell says.

But other tech is growing in popularity. Urine diverting toilets can recapture the phosphorus in liquids. Adding magnesium to wastewater can create “struvite” crystals, an alternative fertilizer. Another method could make fertilizer pellets from dried manure sludge after anaerobic digestion (which also generates biogas fuel).

Biotech might lessen the need for fertilizer, says Elser—although these concepts are in earlier stages. Theoretically, biologists could breed or engineer crops to extract phosphorus more efficiently; researchers have already identified genes that boost phosphorus absorption. Lab-grown meat could cut demand for livestock and the cropland that supports them. And as a simpler solution, eating less meat could do the same. “The less meat we have to grow in the form of cows or pigs, the less feed we have to grow to feed them,” Elser says.

Elser takes inspiration from the progress the world has made in its transition to renewable energy—he thinks agriculture can become more sustainable too. With better phosphorus recycling throughout the food system, the world’s fertilizer could flow more easily to the places that need it. “Eventually, we're going to have to get to a system that's better than the one we have,” Elser says. “When that happens—I’m not sure.”

The World’s Farms Are Hooked on Phosphorus. It’s a Problem

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Microsoft wants to know how many out-of-support copies of Office are installed on Windows PCs, and it intends to find out by pushing a patch through Microsoft Update that it swears is safe, not that you asked.

Quietly mentioned in a support post this week, update KB5021751 is targeting versions of Office "including" 2007 and 2010, both of which have been out of service for several years. Office 2013 is also being asked after as it's due to lose support this coming April.

"This update will run one time silently without installing anything on the user's device," Microsoft said, followed by instructions on how to download and install the update, which Microsoft said has been scanned to ensure it's not infected by malware.

"Microsoft scanned this file for viruses by using the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to it," the Windows giant said on the update notice page.

No restart is needed after installation, Microsoft said.

Are you ready for your mystery update?

Microsoft's description of its out-of-support Office census update leaves much to the imagination, including whether the paragraph describing installation of the update, directly contradicting the paragraph above, is simply misplaced boilerplate language that doesn't apply to KB5021751.

Also missing is any explanation of how the update will gather info on Office installations, whether it is collecting any other system information or what exactly will be transmitted and stored by Microsoft.

Because the nature of the update is unclear, it's also unknown what may be left behind after it runs. Microsoft said that it is a single-run, silent process, but left off mention of traces of the update that may be left behind.

Ultimately, it's expected to phone home to Microsoft to let the mothership know if you're running an old Office.

Microsoft also failed to mention what it intends to do with the data it collects from the update, though one can guess.

We've posed all those questions to Microsoft, and we'll update this story if they respond.

Opting out

Those uncomfortable running an update that's gathering and transmitting unknown system info to Microsoft aren't out of luck, provided you're comfortable doing some Windows troubleshooting. Microsoft's Show or Hide Updates troubleshooter for Windows 10 and 11 is available as a download from Microsoft, and while designed to disable updates that repeatedly fail to install or are causing issues, it can also be used to disable undesired ones from being installed.

Disabling any update can have unforeseen consequences so this, obviously, is done at your own risk. The Register isn't recommending you disable Windows updates if you normally routinely or automatically install them – we're only pointing out that it's an option.

We know that a lot of you go through a cycle of testing updates before deploying them, anyway, for reasons obvious to any Windows admin. ®

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What’s your favorite number? There are literally infinite options, and yet only a few which seem to stand out as more popular than others: there’s seven, obviously; 13 or 666 for the badasses among us; and √2 for anyone who just likes annoying Pythagoreans.

But there’s really only one number out there that can claim to be World Champion: pi. What other mathematical constant is literally used as a benchmark for computing power, or forms the basis for a never-ending worldwide grudge match over who can list the most random digits in the correct order (current record: 111,700)?

The reason pi is able to capture our imagination like this is because it is an irrational number – in other words, its decimal expansion is never-ending and entirely random. It’s thought that any sequence of numbers you can possibly think of can be found somewhere in the expansion of pi, and yet knowing any particular sequence somewhere in the expansion tells you no information about which digit comes next.

Which might make the following sound almost unbelievable: for about a year now, there’s been a way to find any given digit of pi you happen to be interested in.

There’s a catch, of course: it relies on estimates for calculating the Euler and Bernoulli numbers – both sequences which can be quite time- and labor-intensive to calculate, and which grow so quickly that you’d be hard-pressed to even fit them into your calculator, let alone successfully manipulate them to find the 14th digit of pi.

But that’s not exactly the point of the result: “Not only is the formula true but it is also elegant and simple,” says Simon Plouffe, the mathematician who quietly uploaded his formula to the ArXiv preprint server in January 2022. “It is especially for base 2 that it is a beautiful formula. So, I think we can say that the formula is pretty cool.”

Pi in base two is something of a specialty for Plouffe, in fact: he’s the P in the BBP algorithm, a method of calculating the nth digit of the binary expansion of pi which he discovered all the way back in 1995. Now, he says, his result can be extended to any base at all: “By adjusting for base 10 or base 2 it is valid for all n,” he notes. “It can be done in any base if we want, for that I can adjust the formula quite simply.”

Like that 1995 result, the new formula is based on results which “[were] known for centuries,” he tells IFLScience, and yet rarely returned to by working mathematicians. It’s why the most striking thing about the new paper – other than the result itself – is just how short it is: only six pages in total, not counting a short reference section. There are no long calculations or abstract proofs here; instead, Plouffe’s result relies on the ability to just look at something old in a new way.

“It is possible because these Bernoulli numbers are very close to pi and powers of pi,” he tells IFLScience. “The formula which joins them… I would think that it must go back to Euler.”

“They are joined together, so much so that if we isolate pi or pi to the nth power, we have a formula with the nth Bernoulli number, [and] it is so precise that if we truncate at the nth position, we obtain enough precision to affirm that it is the nth decimal.”

Like so many results unraveling this most beguiling of mathematical constants, it’s unlikely that there will be many practical applications for this discovery – after all, even NASA’s absolute highest accuracy calculations, for missions such as interplanetary navigation, only require expansions to about 16 significant figures. It’s difficult, too, to imagine a scenario where you might need to know, say, the 143rd digit of pi, but nothing else about the number.

But for pi-heads and mathematicians alike, it’s not necessarily about how the result can be used so much as what it reminds us of: the idea that surprising mathematical discoveries can be found anywhere, if you just look at things in a fresh way.

Why this result has gone unnoticed for so long, “I confess that I don’t know,” Plouffe tells IFLScience. “[But] to see or discover a property like that you have to look with an eye that is looking for just that.”

“The information contained in a formula… contains an infinity of information,” he adds. “Someone who thinks enough about [it] could very well discover something new.”

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These and other missions that will take astronauts beyond Low Earth Orbit (LEO) and the Earth-Moon system require new technologies, ranging from life support and radiation shielding to power and propulsion.

And when it comes to the latter, Nuclear Thermal and Nuclear Electric Propulsion (NTP/NEP) is a top contender!

NASA and the Soviet space program spent decades researching nuclear propulsion during the Space Race.

A few years ago, NASA reignited its nuclear program for the purpose of developing bimodal nuclear propulsion – a two-part system consisting of an NTP and NEP element – that could enable transits to Mars in 100 days.

New Class of Bimodal NTP/NEP with a Wave Rotor Topping Cycle Enabling Fast Transit to Mars. (Ryan Gosse)

As part of the NASA Innovative Advanced Concepts (NIAC) program for 2023, NASA selected a nuclear concept for Phase I development. This new class of bimodal nuclear propulsion system uses a "wave rotor topping cycle" and could reduce transit times to Mars to just 45 days.

The proposal, titled "Bimodal NTP/NEP with a Wave Rotor Topping Cycle," was put forward by Prof. Ryan Gosse, the Hypersonics Program Area Lead at the University of Florida and a member of the Florida Applied Research in Engineering (FLARE) team.

Gosse's proposal is one of 14 selected by the NAIC this year for Phase I development, which includes a US$12,500 grant to assist in maturing the technology and methods involved. Other proposals included innovative sensors, instruments, manufacturing techniques, power systems, and more.

Nuclear propulsion essentially comes down to two concepts, both of which rely on technologies that have been thoroughly tested and validated.

For Nuclear-Thermal Propulsion (NTP), the cycle consists of a nuclear reactor heating liquid hydrogen (LH2) propellant, turning it into ionized hydrogen gas (plasma) that is then channeled through nozzles to generate thrust.

Several attempts have been made to build a test this propulsion system, including Project Rover, a collaborative effort between the US Air Force and the Atomic Energy Commission (AEC) that launched in 1955.

In 1959, NASA took over from the USAF, and the program entered a new phase dedicated to spaceflight applications. This eventually led to the Nuclear Engine for Rocket Vehicle Application (NERVA), a solid-core nuclear reactor that was successfully tested.

With the closing of the Apollo Era in 1973, the program's funding was drastically reduced, leading to its cancellation before any flight tests could be conducted. Meanwhile, the Soviets developed their own NTP concept (RD-0410) between 1965 and 1980 and conducted a single ground test before the program's cancellation.

Nuclear-Electric Propulsion (NEP), on the other hand, relies on a nuclear reactor to provide electricity to a Hall-Effect thruster (ion engine), which generates an electromagnetic field that ionizes and accelerates an inert gas (like xenon) to create thrust. Attempts to develop this technology include NASA's Nuclear Systems Initiative (NSI) Project Prometheus (2003 to 2005).

Both systems have considerable advantages over conventional chemical propulsion, including a higher specific impulse (Isp) rating, fuel efficiency, and virtually unlimited energy density.

While NEP concepts are distinguished for providing more than 10,000 seconds of Isp, meaning they can maintain thrust for close to three hours, the thrust level is quite low compared to conventional rockets and NTP.

The need for an electric power source, says Gosse, also raises the issue of heat rejection in space – where thermal energy conversion is 30-40 percent under ideal circumstances.

And while NTP NERVA designs are the preferred method for crewed missions to Mars and beyond, this method also has issues providing adequate initial and final mass fractions for high delta-v missions.

This is why proposals that include both propulsion methods (bimodal) are favored, as they would combine the advantages of both. Gosse's proposal calls for a bimodal design based on a solid core NERVA reactor that would provide a specific impulse (Isp) of 900 seconds, twice the current performance of chemical rockets.

Gosse proposed cycle also includes a pressure wave supercharger – or Wave Rotor (WR) – a technology used in internal combustion engines that harnesses the pressure waves produced by reactions to compress intake air.

When paired with an NTP engine, the WR would use pressure created by the reactor's heating of the LH2 fuel to compress the reaction mass further. As Gosse promises, this will deliver thrust levels comparable to that of a NERVA-class NTP concept but with an Isp of 1400-2000 seconds. When paired with a NEP cycle, said Gosse, thrust levels are enhanced even further:

 "Coupled with an NEP cycle, the duty cycle Isp can further be increased (1,800-4,000 seconds) with minimal addition of dry mass. This bimodal design enables the fast transit for manned missions (45 days to Mars) and revolutionizes the deep space exploration of our Solar System."

Based on conventional propulsion technology, a crewed mission to Mars could last up to three years. These missions would launch every 26 months when Earth and Mars are at their closest (aka. a Mars opposition) and would spend a minimum of six to nine months in transit.

A transit of 45 days (six and a half weeks) would reduce the overall mission time to months instead of years. This would significantly reduce the major risks associated with missions to Mars, including radiation exposure, the time spent in microgravity, and related health concerns.

In addition to propulsion, there are proposals for new reactor designs that would provide a steady power supply for long-duration surface missions where solar and wind power are not always available.

Examples include NASA's Kilopower Reactor Using Sterling Technology (KRUSTY) and the hybrid fission/fusion reactor selected for Phase I development by NASA's NAIC 2023 selection.

These and other nuclear applications could someday enable crewed missions to Mars and other locations in deep space, perhaps sooner than we think!

This article was originally published by Universe Today. Read the original article.

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