Science – Page 6

These spiders listen for prey before hurling webs like slingshots

Science / Paul Patrick / December 4, 2024

Along came a spider

A) Untensed web shown from front view. (B) Tensed web shown from side view. Credit: S.I. Han and T.A. Blackledge, 2024

The 19 spiders built 26 webs over the testing period. For the experiments, Han and Blackledge used a weighted tuning fork with frequencies in the mid-range for whirring wings for many mosquito species in North America as a control stimulus. They also attached actual mosquitos to thin strips of black construction paper by dabbing a bit of superglue on their abdomens or hind legs. This ensured the mosquitos could still beat their wings when approaching the webs. The experiments were recorded on high-speed video for analysis.

As expected, spiders released their webs when flapping mosquitoes drew near, but the video footage showed that the releases occurred before the mosquitoes ever touched the web. The spiders released their webs just as frequently when the tuning fork was brandished nearby. It wasn’t likely that they were relying on visual cues because the spiders were centered at the vertex of the web and anchor line, facing away from the cone. Ray spiders also don’t have well-developed eyes. And one spider did not respond to a motionless mosquito held within the capture cone but released its web only when the insect started flapping its wings.

“The decision to release a web is therefore likely based upon vibrational information,” the authors concluded, noting that ray spiders have sound-sensitive hairs on their back legs that could be detecting air currents or sound waves since those legs are typically closest to the cone. Static webs are known to vibrate in response to airborne sounds, so it seems likely that ray spiders can figure out an insect’s approach, its size, or maybe even its behavior before the prey ever makes contact with the web.

As for the web kinematics, Han and Blackledge determined that they can accelerate up to 504 m/s², reaching speeds as high as 1 m/s, and hence can catch mosquitos in 38 milliseconds or less. Even the speediest mosquitoes might struggle to outrun that.

Journal of Experimental Biology, 2024. DOI: 10.1242/jeb.249237 (About DOIs).

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Dog domestication happened many times, but most didn’t pan out

Archaeology, dog domestication, Dogs, indigenous North America, isotope analysis, nitrogen isotopes, Science / Mike M. / December 4, 2024

The story that data reveals is complicated—but somehow very human.

Until about 13,600 years ago, any wolf living in what is now Alaska would have lived on the usual wolf diet: rabbits, moose, and a whole range of other land animals. But starting around 13,600 years ago, the nitrogen isotopes locked in ancient wolves’ bones suggest that something changed. Some wolves still made their living solely by hunting wild game, but others started living almost entirely on fish. Since it’s unlikely that Alaskan wolves had suddenly taken up fly fishing, the sudden change probably suggests that some wolves had started getting food from people.

They’re good dogs, Brent

The fact that we kept trying to befriend wolves is starkly clear at a site called Hollembaek Hill, where archaeologists unearthed the 8,100-year-old remains of four canines. Their diets (according to the nitrogen isotopes locked in their bones) consisted mostly of salmon, so it’s tempting to assume these were domesticated dogs. But their DNA reveals that all four—including a newborn puppy—are most closely related to modern wolves.

On the other hand, the Hollembaek Hill canines didn’t all look like wild wolves. At least one of them had the large stature of a modern wolf, but others were smaller, like early dogs. And some of their DNA suggests that they may be at least part dog but not actually related to modern dogs. Lanoë and his colleagues suggest that people at Hollembaek Hill 8,000 years ago were living alongside a mix of pet wolves (do not try this at home) and wolf-dog hybrids.

All modern dogs trace their roots to a single group of wolves (now extinct) that lived in Siberia around 23,000 years ago. But sometime between 11,300 and 12,800 years ago, the canines from Hollembaek Hill and another Alaskan site called Swan Point had dog DNA that doesn’t seem related to modern dogs at all. That may suggest that dog domestication was a process that happened several times in different places, creating several branches of a dog family tree, but only one stuck around in the long run.

In other words, long after humans “invented” dogs, it seems that people just kept repeating the process, doing the things that created dogs in the first place: allowing the friendliest, least aggressive wild canids to live near their villages and maybe adopting and feeding them.

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Trump nominates Jared Isaacman to become the next NASA administrator

artemis, Donald Trump, human spaceflight, jared isaacman, NASA, Science, Space, space policy, spacex / Tim Belzer / December 4, 2024

President-elect Donald Trump announced Wednesday he has selected Jared Isaacman, a billionaire businessman and space enthusiast who twice flew to orbit with SpaceX, to become the next NASA administrator.

“I am delighted to nominate Jared Isaacman, an accomplished business leader, philanthropist, pilot, and astronaut, as Administrator of the National Aeronautics and Space Administration (NASA),” Trump posted on his social media platform, Truth Social. “Jared will drive NASA’s mission of discovery and inspiration, paving the way for groundbreaking achievements in space science, technology, and exploration.”

In a post on X, Isaacman said he was “honored” to receive Trump’s nomination.

“Having been fortunate to see our amazing planet from space, I am passionate about America leading the most incredible adventure in human history,” Isaacman wrote. “On my last mission to space, my crew and I traveled farther from Earth than anyone in over half a century. I can confidently say this second space age has only just begun.”

Top officials who served at NASA under President Trump and President Obama endorsed Isaacman as the next NASA boss.

“Jared Isaacman will be an outstanding NASA Administrator and leader of the NASA family,” said Jim Bridenstine, who led NASA as administrator during Trump’s first term in the White House. “Jared’s vision for pushing boundaries, paired with his proven track record of success in private industry, positions him as an ideal candidate to lead NASA into a bold new era of exploration and discovery. I urge the Senate to swiftly confirm him.”

Lori Garver, NASA’s deputy administrator during the Obama administration, wrote on X that Isaacman’s nomination was “terrific news,” adding that “he has the opportunity to build on NASA’s amazing accomplishments to pave our way to an even brighter future.”

Isaacman, 41, is the founder and CEO of Shift4, a mobile payment processing platform, and co-founded Draken International, which owns a fleet of retired fighter jets to pose as adversaries for military air combat training. If the Senate confirms his nomination, Isaacman would become the 15th NASA administrator, and the fourth who has flown in space.

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Google’s DeepMind tackles weather forecasting, with great performance

AI, atmospheric science, Computer science, Earth science, meteorology, Science, weather forecasting / Rejus Almole / December 4, 2024

By some measures, AI systems are now competitive with traditional computing methods for generating weather forecasts. Because their training penalizes errors, however, the forecasts tend to get “blurry”—as you move further ahead in time, the models make fewer specific predictions since those are more likely to be wrong. As a result, you start to see things like storm tracks broadening and the storms themselves losing clearly defined edges.

But using AI is still extremely tempting because the alternative is a computational atmospheric circulation model, which is extremely compute-intensive. Still, it’s highly successful, with the ensemble model from the European Centre for Medium-Range Weather Forecasts considered the best in class.

In a paper being released today, Google’s DeepMind claims its new AI system manages to outperform the European model on forecasts out to at least a week and often beyond. DeepMind’s system, called GenCast, merges some computational approaches used by atmospheric scientists with a diffusion model, commonly used in generative AI. The result is a system that maintains high resolution while cutting the computational cost significantly.

Ensemble forecasting

Traditional computational methods have two main advantages over AI systems. The first is that they’re directly based on atmospheric physics, incorporating the rules we know govern the behavior of our actual weather, and they calculate some of the details in a way that’s directly informed by empirical data. They’re also run as ensembles, meaning that multiple instances of the model are run. Due to the chaotic nature of the weather, these different runs will gradually diverge, providing a measure of the uncertainty of the forecast.

At least one attempt has been made to merge some of the aspects of traditional weather models with AI systems. An internal Google project used a traditional atmospheric circulation model that divided the Earth’s surface into a grid of cells but used an AI to predict the behavior of each cell. This provided much better computational performance, but at the expense of relatively large grid cells, which resulted in relatively low resolution.

For its take on AI weather predictions, DeepMind decided to skip the physics and instead adopt the ability to run an ensemble.

Gen Cast is based on diffusion models, which have a key feature that’s useful here. In essence, these models are trained by starting them with a mixture of an original—image, text, weather pattern—and then a variation where noise is injected. The system is supposed to create a variation of the noisy version that is closer to the original. Once trained, it can be fed pure noise and evolve the noise to be closer to whatever it’s targeting.

In this case, the target is realistic weather data, and the system takes an input of pure noise and evolves it based on the atmosphere’s current state and its recent history. For longer-range forecasts, the “history” includes both the actual data and the predicted data from earlier forecasts. The system moves forward in 12-hour steps, so the forecast for day three will incorporate the starting conditions, the earlier history, and the two forecasts from days one and two.

This is useful for creating an ensemble forecast because you can feed it different patterns of noise as input, and each will produce a slightly different output of weather data. This serves the same purpose it does in a traditional weather model: providing a measure of the uncertainty for the forecast.

For each grid square, GenCast works with six weather measures at the surface, along with six that track the state of the atmosphere and 13 different altitudes at which it estimates the air pressure. Each of these grid squares is 0.2 degrees on a side, a higher resolution than the European model uses for its forecasts. Despite that resolution, DeepMind estimates that a single instance (meaning not a full ensemble) can be run out to 15 days on one of Google’s tensor processing systems in just eight minutes.

It’s possible to make an ensemble forecast by running multiple versions of this in parallel and then integrating the results. Given the amount of hardware Google has at its disposal, the whole process from start to finish is likely to take less than 20 minutes. The source and training data will be placed on the GitHub page for DeepMind’s GraphCast project. Given the relatively low computational requirements, we can probably expect individual academic research teams to start experimenting with it.

Measures of success

DeepMind reports that GenCast dramatically outperforms the best traditional forecasting model. Using a standard benchmark in the field, DeepMind found that GenCast was more accurate than the European model on 97 percent of the tests it used, which checked different output values at different times in the future. In addition, the confidence values, based on the uncertainty obtained from the ensemble, were generally reasonable.

Past AI weather forecasters, having been trained on real-world data, are generally not great at handling extreme weather since it shows up so rarely in the training set. But GenCast did quite well, often outperforming the European model in things like abnormally high and low temperatures and air pressure (one percent frequency or less, including at the 0.01 percentile).

DeepMind also went beyond standard tests to determine whether GenCast might be useful. This research included projecting the tracks of tropical cyclones, an important job for forecasting models. For the first four days, GenCast was significantly more accurate than the European model, and it maintained its lead out to about a week.

One of DeepMind’s most interesting tests was checking the global forecast of wind power output based on information from the Global Powerplant Database. This involved using it to forecast wind speeds at 10 meters above the surface (which is actually lower than where most turbines reside but is the best approximation possible) and then using that number to figure out how much power would be generated. The system beat the traditional weather model by 20 percent for the first two days and stayed in front with a declining lead out to a week.

The researchers don’t spend much time examining why performance seems to decline gradually for about a week. Ideally, more details about GenCast’s limitations would help inform further improvements, so the researchers are likely thinking about it. In any case, today’s paper marks the second case where taking something akin to a hybrid approach—mixing aspects of traditional forecast systems with AI—has been reported to improve forecasts. And both those cases took very different approaches, raising the prospect that it will be possible to combine some of their features.

Nature, 2024. DOI: 10.1038/s41586-024-08252-9 (About DOIs).

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Seagrass is fantastic at carbon capture—and it’s at risk of extinction

climate change, eel grass, Science, sea grass, syndication / Paul Patrick / December 4, 2024

An underwater gardening experiment along the East Coast aims at restoration.

A crab inhabits a bed of eelgrass at Cape Cod National Seashore in Massachusetts. Eelgrass provides critical habitat for hundreds of species. Credit: Holly Plaisted/National Park Service

In late September, seagrass ecologist Alyssa Novak pulled on her neoprene wetsuit, pressed her snorkel mask against her face, and jumped off an oyster farming boat into the shallow waters of Pleasant Bay, an estuary in the Cape Cod National Seashore in Massachusetts. Through her mask she gazed toward the sandy seabed, about 3 feet below the surface at low tide, where she was about to plant an experimental underwater garden of eelgrass.

Naturally occurring meadows of eelgrass—the most common type of seagrass found along the East Coast of the United States—are vanishing. Like seagrasses around the world, they have been plagued for decades by dredging, disease, and nutrient pollution from wastewater and agricultural runoff. The nutrient overloads have fueled algal blooms and clouded coastal waters with sediments, blocking out sunlight the marine plants need to make food through photosynthesis and suffocating them.

The United Nations Environment Program reports more than 20 of the world’s 72 seagrass species are on the decline. As a result, an estimated 7 percent of these habitats are lost each year.

In the western Atlantic, some eelgrass meadows have been reduced by more than 90 percent in the last 100 years, according to The Nature Conservancy, an environmental nonprofit that works to protect lands and waters around the world.

Now, rising sea surface temperatures caused by global warming are pushing the plant to the brink of extinction. Novak, a research assistant professor at Boston University who has studied eelgrass in New England for more than a decade, and a multidisciplinary team of scientists in different states are trying their best to make sure this does not become reality.

Together, they are working to restore eelgrass populations in coastal parks from Maine to North Carolina using a novel approach that has never been tried before with a marine plant: assisted migration.

“We’re trying to identify thermo-tolerant individuals up and down the East Coast and try to move them into areas where the populations are stressed by increases in sea surface temperature, so that we can give those populations a chance of surviving into the future,” Novak said.

Typically, eelgrass thrives in water temperatures between 60° and 68° Fahrenheit, according to Novak. In the last 20 years, sea surface temperatures in the Northeast have warmed faster than the global ocean and exceeded that safe range, mostly due to human activity like burning fossil fuels, according to NOAA Fisheries, a federal agency charged with managing and protecting marine resources in the US.

Blades of eelgrass are viewed up close at Cape Cod National Seashore. Credit: Holly Plaisted/National Park Service

Around 77° Fahrenheit the plants become stressed and struggle to photosynthesize, said Novak. Around 82° they begin to expire. “That’s when the plants no longer can handle the heat stress, and they end up dying,” she said. And it’s getting hotter.

In recent years, she said, water temperatures along the East Coast have surpassed 82° during peak summer months. By 2050, they are expected to increase in the Northeast by two degrees, she said.

The common garden experiment

Anticipating the deadly forecast for eelgrass, The Nature Conservancy brought together a group of scientists in 2022 to figure out how they might change the plant’s trajectory. Together, the experts on seagrasses, corals, agriculture, forestry, and plant genetics explored options based on what had been done to address the effects of climate change on other ecosystems.

“We wanted to figure out what the solutions were that different groups had come up with, and from those, which ones might apply to the seagrass world,” said Boze Hancock, senior marine restoration scientist with The Nature Conservancy’s global oceans team.

Prolonged marine heatwaves and coral disease have prompted some scientists to experiment with cross-breeding and replanting heat-resistant corals in warming waters, for example. In some cases they have removed whole coral colonies from their natural habitat to preserve their genetics in land-based biobanks.

One of the workshop invitees, biologist Thomas Whitham, shared with the group how he’s used a scientific research tool called the “common garden experiment” to restore deciduous Fremont cottonwood forests that have been dying off in Arizona due to rising temperatures and drought.

The experiments involve collecting plants from different locations and moving them to designated locations to observe how they respond to new environmental conditions. In the case of Fremont cottonwoods, Whitham said the technique has proven vital to identifying trees with specific genetic traits that make them more heat and drought resilient. Cuttings from these trees are now being planted in areas where less resilient trees died off to restore the species in a process known as “assisted migration.”

“We’ve planted many thousands, tens of thousands, of trees using this common garden approach,” said Whitham, a Regents’ professor in the department of biological sciences at Northern Arizona University. It could work for eelgrass too, he told the group.

They could collect seeds from eelgrass populations in the south and plant them in cooler northern waters alongside local seeds and, in effect, identify plants that have a propensity to thrive in warmer temperatures.

Workshop participants were eager to try, said attendee Jonathan Lefcheck, a research scientist at the University of Maryland Center for Environmental Science who has studied seagrasses in the Chesapeake Bay for more than 15 years. “If we do nothing, it’s likely that seagrass—eelgrass—will be extirpated all the way up to New York in the next 50 years,” he said. And with it, all the services it provides to wildlife and humans.

Underwater forests

Eelgrass provides critical habitat for hundreds of species.

“It’s the forest under the water in the estuaries,” said Bradley Peterson, a professor of marine science at Stony Brook University’s School of Marine and Atmospheric Sciences who helped initiate the workshops in collaboration with The Nature Conservancy.

Scientists believe seagrasses evolved from terrestrial plants 70 to 100 millions years ago. “When they went into the marine world, they brought all the machinery they had with them for the terrestrial world, real seeds, real flowers, and real roots,” said Peterson, who is working to restore eelgrass near Long Island.

Its green grass blades, which can grow up to a couple feet long, offer food and shelter to horseshoe crabs, seahorses, and fish of all sizes that weave through its mazes. Little shrimp pollinate the plant’s flowers like “bees of the sea,” said Lefcheck. For bigger fish, “it’s this beautiful buffet,” he said. “You get this whole ecosystem that’s built up around this habitat that’s just sort of gently swaying there underneath the waves.”

In New England, eelgrass is vital for commercial scallop and oyster fisheries. Same for the Atlantic cod. “The cod industry is massive, so if you start losing that habitat, then your commercial fisheries go,” Novak said.

You also lose important coastline protection. Seagrass helps prevent erosion and buffers shorelines from flooding and storm surge. It can reduce wave energy by 50 percent, according to Novak. It also improves water quality and clarity by filtering pollutants and storing excess nutrients, reducing the prevalence of bacteria that can cause coral disease or contaminate seafood. “If you lose eelgrass, you’re going to have dirtier waters,” she said. Global warming could also be exacerbated.

tuft of eel grass — Eelgrass is the most dominant type of seagrass along the East Coast. Credit: d3_plus D.Naruse @ Japan via Getty

Seagrasses sequester up to 18 percent of carbon stored in the ocean, capturing it 35 times faster than tropical rainforests, according to the World Wide Fund for Nature. The New York Department of State, Office of Planning, Development and Community Infrastructure reports each acre of seagrass can potentially sequester the same amount of carbon emitted by a car driving nearly 4,000 miles each year. But when this unique marine habitat is destroyed, carbon that has been stored in the plant’s roots and sediments—sometimes for thousands of years—is released back into the atmosphere, said Novak.

Sharing seeds

To have a chance at repopulating eelgrass along the East Coast, scientists like Novak, Peterson, and Lefcheck realized they would have to share information and collaborate across state borders—something to which academics are not always accustomed, according to Novak.

“It’s not our nature to share information that freely, because we’re supposed to be focusing on publishing,” she said. But the crisis at hand had inspired a change in the status quo. “We’re a team,” she said. “We’re about saving the eelgrass and doing what’s best for this ecosystem.”

They call the regional effort HEAT (Helping Eelgrass Adapt to Temperature). In the last year, participants have been working together to identify the best possible sites for planting common gardens along the East Coast. So far, they’ve homed in on several national parks: the Cape Cod National Seashore, Fire Island National Seashore in New York, Assateague Island in Maryland and Cape Hatteras and Cape Lookout national seashores in North Carolina.

“We want to set ourselves up for some success and use the information we have about these parks to guide our decision-making and make sure we’re putting these in places where they might have enough light, where they won’t have as many human impacts,” said Lefcheck.

They’ve also begun collecting and sharing seeds. “We’re sharing actual plants with each other for genomics, and then we’re also sharing seeds with each other for doing our common gardens and for experiments,” Novak said.

This past year Novak sent samples of eelgrass plants collected in Massachusetts to the University of North Carolina Wilmington for Stephanie Kamel, a professor in the department of biology and marine biology at the university, to analyze. Kamel is looking for plants that have specific genetic markers that might make them more resilient to challenging environmental conditions like warmer temperatures and lower light, which is becoming an increasing problem as sea levels rise due to global warming pushing the plants deeper underwater. Currently, she’s analyzing the DNA of 800 eelgrass plants from 60 meadows along the East Coast. “We’re going to have this sort of unprecedented level of detail about genomic variation across the range of Zostera (eelgrass),” said Kamel.

This information could be used to help collaborators figure out which seeds they should plant in different locations based on their specific environmental conditions and challenges, said Jessie Jarvis, a seagrass ecologist and professor who works with Kamel at the University of North Carolina Wilmington.

“It’s almost like a dating app for seagrass,” Jarvis said. “You could be a little bit smarter about picking your source populations to match what your restoration needs are, rather than just kind of throwing seeds from everywhere and hoping that something works.”

In the meantime, though, common gardening remains the most practical tool to figure out which plants from which locations may be the best stock for future eelgrass populations. This past year Kamel and Jarvis piloted a common garden experiment in North Carolina and Virginia.

“We took those seeds from what we thought were, quote, unquote, good sources (in North Carolina), and we actually moved them to Virginia. And then we took some Virginia seeds and moved them to North Carolina to actually see what would happen in terms of growth,” said Kamel. While it’s still too early to draw firm conclusions from the experiment, Kamel said preliminary results seem promising. “There are really encouraging signs that we have been able to find some genomic changes associated with temperature resilience,” she said.

Others are following suit. This past spring, Novak and Peterson harvested reproductive eelgrass shoots filled with seeds while snorkeling and scuba diving in Acadia National Park in Maine and Cape Cod, Nantucket, Gloucester in Massachusetts. Lefcheck harvested in Maryland. “What we do is harvest them before they’ve released the seeds, because the seeds are tiny, like the size of a pinhead,” Lefcheck said. The shoots are then held in saltwater tanks until the seeds drop and can easily be collected and stored until it’s time to plant them.

It’s best to wait to plant eelgrass in the early fall, after most of the late summer storms have passed, according to Novak, who spent several days planting seeds in Pleasant Bay and nearby East Harbor this September with a team including a biologist from the National Park Service and a representative from the Mashpee Wampanoag Tribe. To get to the Pleasant Bay site, they motored out onto the water on an oyster farming boat. “The oyster farmers are interested in the project because our site is adjacent to their farm and they recognize that healthy beds are important to sustaining their livelihood,” Novak said.

Before getting wet, Novak and her team ran through their gardening plan. “We do dry runs on land, just to get everybody organized, but it’s not the same when you get into the water,” she said. “You’re trying to hold things underwater. You can’t see as well, even if you have a mask on.”

They would establish two 25-meter transect lines and then plant seeds from different donor sites in New York and Massachusetts. Nantucket was one of them. “We knew conditions were warmer at that particular site, so we said, let’s, let’s test them at Cape Cod,” she said.

Up to 500 seeds from each location would be planted by releasing them into the water column from a test tube or dropping tea bags filled with the seeds that would meander their way down to the seabed into 1-meter plots.

It was a slow process, Novak said, requiring hyper organization to make sure it’s clear which seeds have been planted where so that they can be monitored. In January, she will return to the sites to see if the plants are germinating. Then in the spring she’ll really be able to measure growth and compare how the different plants are faring in comparison to one another. “By next summer, we should have genomics for all of our populations, so that should really be guiding our efforts at that point,” she said.

Teresa Tomassoni is an environmental journalist covering the intersections between oceans, climate change, coastal communities, and wildlife for Inside Climate News. Her previous work has appeared in The Washington Post, NPR, NBC Latino, and the Smithsonian American Indian Magazine. Teresa holds a graduate degree in journalism from the Craig Newmark Graduate School of Journalism. She is also a recipient of the Stone & Holt Weeks Social Justice Reporting Fellowship. In addition to reporting on oceans, Teresa teaches climate solutions reporting for The School of the New York Times.

This story originally appeared on Inside Climate News.

Seagrass is fantastic at carbon capture—and it’s at risk of extinction Read More »

Splash pads really are fountains of fecal material; CDC reports 10K illnesses

CDC, cyrptosporidium, gastrointestinal diseases, health, Infectious disease, kids, public health, Science, splash pads / Paul Patrick / December 3, 2024

Once infectious material gets into the water, disinfection systems that aren’t working properly or are inadequate can allow pathogens to gush from every nozzle. Splash pads aren’t unique in having to handle sick children in poopy swim diapers—but they are unique in how they are regulated. That is, in some places, they’re not regulated at all. Splash pads are designed to not have standing water, therefore reducing the risk of young children drowning. But, because they lack standing water, they are sometimes deemed exempt from local health regulations. Before 2000, only 13 states regulated splash pads. Though many states have since added regulations, some did so only after splash pad-linked outbreaks were reported.

Downpour of disease

The primary method for keeping recreational water free of infectious viruses and bacteria is chlorinating it. However, maintaining germ-killing chlorine concentration is especially difficult for splash pads because the jets and sprays aerosolize chlorine, lowering the concentration.

Still, in most splash-pad linked outbreaks, standard chlorine concentrations aren’t enough anyway. The most common pathogen to cause an outbreak at splash pads is the parasite Cryptosporidium, aka Crypto. The parasite’s hardy spores, called oocysts, are extremely tolerant of chlorine, surviving in water with the standard chlorine concentration (1 ppm free chlorine) for over seven days. (Other germs die in minutes.) In splash pads that might not even have that standard chlorine concentration, Crypto flourishes and can cause massive outbreaks.

In 2023, the CDC recommended new health codes that call for “secondary disinfection” methods to keep Crypto at bay, including disinfection systems using ozone or ultraviolet light. Another possible solution is to have “single-pass” splash pads that don’t recirculate water.

In all, to keep splash pads from being geysers of gastrointestinal parasites and pathogens, various changes have to happen, the CDC experts say.

“Prevention of waterborne disease outbreaks at splash pads requires changes in user behavior; recreational venue code updates; and improved venue design, construction, operation, and management of facilities,” they conclude. But it should all start with keeping kids from sitting on jets and drinking the water.

Splash pads really are fountains of fecal material; CDC reports 10K illnesses Read More »

A peek inside the restoration of the iconic Notre Dame cathedral

architecture, National Geographic, notre dame, Notre Dame restoration, photography, Science / Mike M. / December 3, 2024

Tomas van Houtyryve’s striking photographs for National Geographic capture the restoration process.

Notre Dame’s nave is clean and bright thanks to a latex application that peeled away soot and lead. Credit: Tomas van Houtryve for National Geographic

On April 15, 2019, the world watched in transfixed horror as a fire ravaged the famed Cathedral of Notre Dame in Paris, collapsing the spire and melting the lead roof. After years of painstaking restoration costing around $740 million, the cathedral reopens to the public this weekend. The December issue of National Geographic features an exclusive look inside the restored cathedral, accompanied by striking photographs by Paris-based photographer and visual artist Tomas van Houtryve.

For several hours, it seemed as if the flames would utterly destroy the 800-year-old cathedral. But after a long night of work by more than 400 Paris firefighters, the fire finally began to cool and attention began to shift to what could be salvaged and rebuilt. French President Emmanuel Macron vowed to restore Notre Dame to its former glory and set a five-year deadline. The COVID-19 pandemic caused some delays, but France nearly met that deadline regardless.

Those reconstruction efforts were helped by the fact that, a few years before the fire, scientist Andrew Tallon had used laser scanning to create precisely detailed maps of the interior and exterior of the cathedral—an invaluable aid as Paris rebuilds this landmark structure. French acousticians had also made detailed measurements of Notre Dame’s “soundscape” that were instrumental in helping architects factor acoustics into their reconstruction plans. The resulting model even enabled Brian FG Katz, research director of the National Center for Scientific Research (CNRS) at Sorbonne University, to create a virtual reality version of Notre Dame with all the acoustical parameters in place.

A devastating fire

Flames and smoke billowing from the roof of Notre Dame cathedral in Paris, France, on April 15, 2019. — Flames and smoke billowing from the roof of Notre Dame cathedral in Paris on April 15, 2019. Credit: Pierre Suu/Getty Images

As we previously reported, Notre Dame’s roof and its support structure of 800-year-old oak timbers had almost completely succumbed to the flames. Firefighters reported the cathedral’s bell towers safe and said that many works of art had been rescued or were already stored in areas believed to be safe from the fire. The main spire—750 tons of oak lined with lead—collapsed in flames, landing on the wooden roof, which was destroyed. The trees that made up the roof’s wooden structure were cut down around 1160.

Thanks to the efforts of preservationists like Philippe Villeneuve, chief architect of historic monuments, the cathedral has been rebuilt nearly exactly as it was before the fire. The interior is most transformed since the walls, stained glass, paintings, and sculptures were all cleaned and restored for the first time since the 19th century. All the furnishings have been replaced, and sculptor and designer Guillaume Bardet was committed to creating a new altar and various liturgical items, including a new baptismal font and massive bronze altar. (The original stone altar was crushed as the collapsing spire plunged to the main floor.)

Much of the structural repairs will not be readily apparent to visitors, most notably the cathedral’s attic and roof, which were rebuilt with new hand-hewed timber trusses fixed in place by pegged mortise-and-tenon joints. One modern improvement: “Fire-resistant trusses at the crossing will isolate the spire and the two transept arms from the nave and the choir, so a fire can never again race through the entire attic,” Robert Kunzig wrote in the NatGeo article. “Should flames break out in this space, misters distributed throughout the attic will help suppress them until firefighters can climb hundreds of stairs.”

A photographer speaks

National Geographic was granted special access throughout the reconstruction process and tapped van Houtryve to capture everything in photographs and video footage. Ars caught up with him to learn more.

Designer Guillaume Bardet was hired to create a new bronze altar and pulpit, among other new liturgical furnishings. Credit: Tomas van Houtryve for National Geographic

Ars Technica: How did you get involved in documenting the cathedral’s restoration in photos/video?

Tomas van Houtryve: My journey in documenting the restoration of Notre-Dame de Paris began with an incredible opportunity through National Geographic’s partnership with Rebâtir Notre-Dame de Paris. I’ve always been drawn to the intersection of history and architecture, and I immediately knew I wanted to be a part of this project. It just so happened that through National Geographic and Rebâtir, I was able to perfectly combine my passion for visual storytelling with my deep connection to the city. Being entrusted to capture such a monumental effort felt like a natural progression in my career as a photographer—challenging, inspiring, and deeply meaningful.

Ars Technica: What were the biggest challenges in capturing this years-long process on camera?

Tomas van Houtryve: From a working standpoint, one of the biggest challenges was the high level of lead contamination. To be on-site, I had to wear a hazmat suit and often a respirator mask, which added a layer of physical difficulty to the work. Another significant hurdle was the heights. Thankfully, my background in rock climbing and the rope access training I completed with technicians proved invaluable. Once on-site, this assignment demanded every skill I’ve ever learned as a photographer. From flying drones in sensitive areas and mastering architectural photography to conducting the historic wet plate process with a 19th-century wooden camera, I applied everything in my visual toolbox. It was an all-encompassing challenge, but also an incredibly rewarding one.

Ars Technica: Was there any special equipment (lenses, cranes, etc.) needed to capture the photos and footage?

Tomas van Houtryve: It’s difficult to convey just how awe-inspiring the Notre-Dame de Paris restoration site is unless you see it in person. Stepping inside felt almost like entering a space station. There was an otherworldly blend of towering scaffolding, echoing sounds of the craftsmen at work, and the unique atmosphere of the cathedral itself. To document the restoration, I used a combination of modern and historic technology. Drones allowed me to navigate the intricate scaffolding and capture aerial perspectives that most people wouldn’t normally be able to see. And I also used a 19th-century wooden camera and portable darkroom to create glass plate photographs using the historic wet plate process. It was an incredible merging of the old and the new—a perfect representation of what Notre-Dame is and how it’s being restored.

Credit: Tomas van Houtryve for National Geographic

Ars Technica: What were some of the particular highlights for you as part of this long process?

Tomas van Houtryve: One of the standout highlights for me was witnessing the incredible craftsmanship that went into every detail of the restoration. Seeing the artisans, stonemasons, and carpenters recreate original elements with such precision and care was something that was very special. It gave me a deep appreciation for the skill and dedication involved in bringing Notre Dame back to life.

Another remarkable highlight was witnessing the transformation of the cathedral itself. Many people don’t realize that Gothic cathedrals like Notre-Dame de Paris were originally designed to be light, bright, and vibrant spaces of worship. Over centuries, time and human interaction dulled their appearance, creating the more imposing image we often associate with them. Seeing the cathedral fully cleaned, with its light stone walls restored to their original brilliance, felt like stepping back in time to another world. It was awe-inspiring to see the cathedral as it was meant to be, a true testament to its enduring beauty.

Ars Technica: As a Parisian, what has it meant to you to see Notre Dame restored to its former glory?

Tomas van Houtryve: Although I wasn’t born a Parisian, the years I’ve spent living here have made me feel deeply connected to this city—it’s my true home. On the night of the fire in 2019, every Parisian, including myself, watched in horror as our geographical epicenter—Notre-Dame de Paris—went up in flames. I’ll never forget it, and we’ve been haunted in some ways since then. Being trusted to photograph this monumental restoration, a feat of both engineering and unwavering passion, was not only a once-in-a-lifetime opportunity, but it was cathartic. Contributing, even in a small way, to preserving the legacy of such an iconic symbol was both humbling and profoundly inspiring.

Cover of the December 2024 issue of National Geographic magazine — Credit: National Geographic

Jennifer is a senior reporter at Ars Technica with a particular focus on where science meets culture, covering everything from physics and related interdisciplinary topics to her favorite films and TV series. Jennifer lives in Baltimore with her spouse, physicist Sean M. Carroll, and their two cats, Ariel and Caliban.

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Cheerios effect inspires novel robot design

3D printing, active matter, Cheerios effect, fluid dynamics, Marangoni effect, Physics, robotics, Science / Kris Guyer / December 3, 2024

There’s a common popular science demonstration involving “soap boats,” in which liquid soap poured onto the surface of water creates a propulsive flow driven by gradients in surface tension. But it doesn’t last very long since the soapy surfactants rapidly saturate the water surface, eliminating that surface tension. Using ethanol to create similar “cocktail boats” can significantly extend the effect because the alcohol evaporates rather than saturating the water.

That simple classroom demonstration could also be used to propel tiny robotic devices across liquid surfaces to carry out various environmental or industrial tasks, according to a preprint posted to the physics arXiv. The authors also exploited the so-called “Cheerios effect” as a means of self-assembly to create clusters of tiny ethanol-powered robots.

As previously reported, those who love their Cheerios for breakfast are well acquainted with how those last few tasty little “O”s tend to clump together in the bowl: either drifting to the center or to the outer edges. The “Cheerios effect is found throughout nature, such as in grains of pollen (or, alternatively, mosquito eggs or beetles) floating on top of a pond; small coins floating in a bowl of water; or fire ants clumping together to form life-saving rafts during floods. A 2005 paper in the American Journal of Physics outlined the underlying physics, identifying the culprit as a combination of buoyancy, surface tension, and the so-called “meniscus effect.”

It all adds up to a type of capillary action. Basically, the mass of the Cheerios is insufficient to break the milk’s surface tension. But it’s enough to put a tiny dent in the surface of the milk in the bowl, such that if two Cheerios are sufficiently close, the curved surface in the liquid (meniscus) will cause them to naturally drift toward each other. The “dents” merge and the “O”s clump together. Add another Cheerio into the mix, and it, too, will follow the curvature in the milk to drift toward its fellow “O”s.

Physicists made the first direct measurements of the various forces at work in the phenomenon in 2019. And they found one extra factor underlying the Cheerios effect: The disks tilted toward each other as they drifted closer in the water. So the disks pushed harder against the water’s surface, resulting in a pushback from the liquid. That’s what leads to an increase in the attraction between the two disks.

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Researchers finally identify the ocean’s “mystery mollusk”

Biology, marine biology, phylogenetic, Science, Weird / Mike M. / December 2, 2024

Some of the most bizarre lifeforms on Earth lurk in the deeper realms of the ocean. There was so little known about one of these creatures that it took 20 years just to figure out what exactly it was. Things only got weirder from there.

The organism’s distinctive, glowing presence was observed by multiple deep-sea missions between 2000 to 2021 but was simply referred to as “mystery mollusk.” A team of Monterey Bay Aquarium Research Institute (MBARI) researchers has now reviewed extensive footage of past mystery mollusk sightings and used MBARI’s remotely operated vehicles (ROVs) to observe it and collect samples. They’ve given it a name and have finally confirmed that it is a nudibranch—the first and only nudibranch known to live at such depths.

Bathydevius caudactylus, as this nudibranch is now called, lives 1,000–4,000 meters (3,300–13,100 feet) deep in the ocean’s bathypelagic or midnight zone. It moves like a jellyfish, eats like a Venus flytrap, and is bioluminescent, and its genes are distinct enough for it to be classified as the first member of a new phylogenetic family.

“Anatomy, diet, behavior, bioluminescence, and habitat distinguish this surprising nudibranch from all previously described species, and genetic evidence supports its placement in a new family,” the MBARI research team said in a study recently published in Deep Sea Research.

Is that a…?

Nudibranchs are gastropods, which literally translates to “stomach foot” since the “foot” they crawl around on when not swimming is right below their guts. They are part of a larger group that includes terrestrial and aquatic snails and slugs. B. caudactylus, however, seems to get around more like a jellyfish than a sea slug. It mostly swims using an oral hood that opens and closes to propel itself backward through the water in a manner similar to many jellyfish.

The hood of B. caudactylus can also act something like a Venus flytrap. While it is not a hinged structure like the leaves of the plant, it is used to trap prey. Typically small crustaceans, the prey are then pushed to the mouth at the back of the hood.

The mystery mollusk.

The nudibranch also seems to have a unique way of avoiding becoming food itself. Projections at the end of its tail, known as dactyls, can detach if needed, much like the tails of some lizard species. The MBARI team thinks that these dactyls are possibly a lure meant to trick predators while the nudibranch swims away. They later regenerate.

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People will share misinformation that sparks “moral outrage”

Behavioral science, Human behavior, misinformation, rage clicks, Science, Social Media / Kris Guyer / December 2, 2024

People can tell it’s not true, but if they’re outraged by it, they’ll share anyway.

Rob Bauer, the chair of a NATO military committee, reportedly said, “It is more competent not to wait, but to hit launchers in Russia in case Russia attacks us. We must strike first.” These comments, supposedly made in 2024, were later interpreted as suggesting NATO should attempt a preemptive strike against Russia, an idea that lots of people found outrageously dangerous.

But lots of people also missed a thing about the quote: Bauer has never said it. It was made up. Despite that, the purported statement got nearly 250,000 views on X and was mindlessly spread further by the likes of Alex Jones.

Why do stories like this get so many views and shares? “The vast majority of misinformation studies assume people want to be accurate, but certain things distract them,” says William J. Brady, a researcher at Northwestern University. “Maybe it’s the social media environment. Maybe they’re not understanding the news, or the sources are confusing them. But what we found is that when content evokes outrage, people are consistently sharing it without even clicking into the article.” Brady co-authored a study on how misinformation exploits outrage to spread online. When we get outraged, the study suggests, we simply care way less if what’s got us outraged is even real.

Tracking the outrage

The rapid spread of misinformation on social media has generally been explained by something you might call an error theory—the idea that people share misinformation by mistake. Based on that, most solutions to the misinformation issue relied on prompting users to focus on accuracy and think carefully about whether they really wanted to share stories from dubious sources. Those prompts, however, haven’t worked very well. To get to the root of the problem, Brady’s team analyzed data that tracked over 1 million links on Facebook and nearly 45,000 posts on Twitter from different periods ranging from 2017 to 2021.

Parsing through the Twitter data, the team used a machine-learning model to predict which posts would cause outrage. “It was trained on 26,000 tweets posted around 2018 and 2019. We got raters from across the political spectrum, we taught them what we meant by outrage, and got them to label the data we later used to train our model,” Brady says.

The purpose of the model was to predict whether a message was an expression of moral outrage, an emotional state defined in the study as “a mixture of anger and disgust triggered by perceived moral transgressions.” After training, the AI was effective. “It performed as good as humans,” Brady claims. Facebook data was a bit more tricky because the team did not have access to comments; all they had to work with were reactions. The reaction the team chose as a proxy for outrage was anger. Once the data was sorted into outrageous and not outrageous categories, Brady and his colleagues went on to determine whether the content was trustworthy news or misinformation.

“We took what is now the most widely used approach in the science of misinformation, which is a domain classification approach,” Brady says. The process boiled down to compiling a list of domains with very high and very low trustworthiness based on work done by fact-checking organizations. This way, for example, The Chicago Sun-Times was classified as trustworthy; Breitbart, not so much. “One of the issues there is that you could have a source that produces misinformation which one time produced a true story. We accepted that. We went with statistics and general rules,” Brady acknowledged. His team confirmed that sources classified in the study as misinformation produced news that was fact-checked as false six to eight times more often than reliable domains, which Brady’s team thought was good enough to work with.

Finally, the researchers started analyzing the data to answer questions like whether misinformation sources evoke more outrage, whether outrageous news was shared more often than non-outrageous news, and finally, what reasons people had for sharing outrageous content. And that’s when the idealized picture of honest, truthful citizens who shared misinformation just because they were too distracted to recognize it started to crack.

Going with the flow

The Facebook and Twitter data analyzed by Brady’s team revealed that misinformation evoked more outrage than trustworthy news. At the same time, people were way more likely to share outrageous content, regardless of whether it was misinformation or not. Putting those two trends together led the team to conclude outrage primarily boosted the spread of fake news since reliable sources usually produced less outrageous content.

“What we know about human psychology is that our attention is drawn to things rooted in deep biases shaped by evolutionary history,” Brady says. Those things are emotional content, surprising content, and especially, content that is related to the domain of morality. “Moral outrage is expressed in response to perceived violations of moral norms. This is our way of signaling to others that the violation has occurred and that we should punish the violators. This is done to establish cooperation in the group,” Brady explains.

This is why outrageous content has an advantage in the social media attention economy. It stands out, and standing out is a precursor to sharing. But there are other reasons we share outrageous content. “It serves very particular social functions,” Brady says. “It’s a cheap way to signal group affiliation or commitment.”

Cheap, however, didn’t mean completely free. The team found that the penalty for sharing misinformation, outrageous or not, was loss of reputation—spewing nonsense doesn’t make you look good, after all. The question was whether people really shared fake news because they failed to identify it as such or if they just considered signaling their affiliation was more important.

Flawed human nature

Brady’s team designed two behavioral experiments where 1,475 people were presented with a selection of fact-checked news stories curated to contain outrageous and not outrageous content; they were also given reliable news and misinformation. In both experiments, the participants were asked to rate how outrageous the headlines were.

The second task was different, though. In the first experiment, people were simply asked to rate how likely they were to share a headline, while in the second they were asked to determine if the headline was true or not.

It turned out that most people could discern between true and fake news. Yet they were willing to share outrageous news regardless of whether it was true or not—a result that was in line with previous findings from Facebook and Twitter data. Many participants were perfectly OK with sharing outrageous headlines, even though they were fully aware those headlines were misinformation.

Brady pointed to an example from the recent campaign, when a reporter pushed J.D. Vance about false claims regarding immigrants eating pets. “When the reporter pushed him, he implied that yes, it was fabrication, but it was outrageous and spoke to the issues his constituents were mad about,” Brady says. These experiments show that this kind of dishonesty is not exclusive to politicians running for office—people do this on social media all the time.

The urge to signal a moral stance quite often takes precedence over truth, but misinformation is not exclusively due to flaws in human nature. “One thing this study was not focused on was the impact of social media algorithms,” Brady notes. Those algorithms usually boost content that generates engagement, and we tend to engage more with outrageous content. This, in turn, incentivizes people to make their content more outrageous to get this algorithmic boost.

Science, 2024. DOI: 10.1126/science.adl2829

Jacek Krywko is a freelance science and technology writer who covers space exploration, artificial intelligence research, computer science, and all sorts of engineering wizardry.

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Over the weekend, China debuted a new rocket on the nation’s path to the Moon

china, launch, long march, long march 12, moon, Science, Space / Tim Belzer / December 2, 2024

Depending on how you count them, China now has roughly 18 types of active space launchers.

China’s new Long March 12 rocket made a successful inaugural flight Saturday, placing two experimental satellites into orbit and testing uprated, higher-thrust engines that will allow a larger Chinese launcher in development to send astronauts to the Moon.

The 203-foot-tall (62-meter) Long March 12 rocket lifted off at 9: 25 am EST (14: 25 UTC) Saturday from the Wenchang commercial launch site on Hainan Island, China’s southernmost province. This was also the first rocket launch from a new commercial spaceport at Wenchang, consisting of two launch sites a short distance from a pair of existing launch pads used by heavier rockets primarily geared for government missions.

The two-stage rocket delivered two technology demonstration satellites into a near-circular 50-degree-inclination orbit with an average altitude of nearly 650 miles (about 1,040 kilometers), according to US military tracking data.

The Long March 12 is the newest member of China’s Long March rocket family, which has been flying since China launched its first satellite into orbit in 1970. The Long March rockets have significantly evolved since then and now include a range of launch vehicles of different sizes and designs.

Versions of the Long March 2, 3, and 4 rockets have been flying since the 1970s and 1980s, burning the same toxic mix of hypergolic propellants as China’s early ICBMs. More recently, China debuted the Long March 5, 6, 7, and 8 rockets consuming the cleaner combination of kerosene and liquid oxygen propellants. These new rockets provide China with a spectrum of small, medium, and heavy-lift launch capabilities.

So many rockets

So, why bother with yet another Long March rocket? One reason is that Chinese officials seek a less expensive rocket to deploy thousands of small satellites for the country’s Internet mega-constellations to rival SpaceX’s Starlink network. Another motivation is to demonstrate the performance of upgraded rocket engines, new technologies, and fresh designs, some of which appear to copy SpaceX’s workhorse Falcon 9 rocket.

Like all of China’s other existing rockets, the Long March 12 configuration that flew Saturday is fully disposable. At the Zhuhai Airshow earlier this month, China’s largest rocket company displayed another version of the Long March 12 with a reusable first stage but with scant design details.

The Long March 12 is powered by four kerosene-fueled YF-100K engines on its first stage, generating more than 1.1 million pounds, or 5,000 kilonewtons of thrust at full throttle. These engines are upgraded, higher-thrust versions of the YF-100 engines used on several other types of Long March rockets.

Models of the Long March rockets on display at the China National Space Administration (CNSA) booth during the China International Aviation & Aerospace Exhibition in Zhuhai, China, on November 12, 2024. In this image, models of a future reusable version of the Long March 12 (left) and the super-heavy Long March 9 (right) are visible. Credit: Qilai Shen/Bloomberg via Getty Images

Notably, China will use the YF-100K variant on the heavy-lift Long March 10 rocket in development to launch Chinese astronauts to the Moon. The heaviest version of the Long March 10 will use 21 of these YF-100K engines on its core stage and strap-on boosters. Now, Chinese engineers have tested the upgraded YF-100K in flight, with favorable results from Saturday’s launch.

China is also developing a new crew-rated spacecraft and lunar lander that will launch on Long March 10 rockets, eyeing a human landing on the lunar surface by 2030. The Long March 10 will have a reusable first stage like the Falcon 9, and China is now working on a super-heavy fully reusable rocket that appears to be a clone of SpaceX’s Starship. This Long March 9 rocket, which probably won’t fly until the 2030s, will enable larger-scale sustained lunar exploration by China.

And now, the details

The Long March 12 was developed by the Shanghai Academy of Spaceflight Technology, also known as SAST, one of the two main state-owned organizations in charge of designing and manufacturing Long March rockets. Together with the Beijing-based China Academy of Launch Vehicle Technology, SAST is part of the China Aerospace Science and Technology Corporation, the largest government-run enterprise overseeing the Chinese space program.

According to SAST, the Long March 12 is capable of delivering a payload of at least 12 metric tons (26,455 pounds) into low-Earth orbit and about half that to a somewhat higher Sun-synchronous orbit. Two kerosene-fueled YF-115 engines power the Long March 12’s upper stage.

The Long March 12 is also China’s first 3.8-meter (12.5-foot) diameter rocket, which is an optimal match between the width of the booster and lift capability, allowing it to be transported by railway to launch sites across China, according to the state-run Xinhua news agency.

China’s older Long March rocket variants are slimmer and generally require engineers to strap together multiple first-stage boosters in a cluster arrangement to achieve performance similar to the Long March 12. The core of the heavy-lift Long March 5 is around 5 meters in diameter and must be transported by sea.

China’s first Long March 12 rocket on its launch pad before liftoff. Credit: Photo by VCG/VCG via Getty Images

In a post-launch press release, SAST identified several other “technology breakthroughs” flying on the Long March 12 rocket. These include a health management system that can diagnose anomalies in flight and adjust the rocket’s trajectory in real time to compensate for any minor problems. The Long March 12 is also China’s first rocket to use cryogenic helium to pressurize its liquid oxygen tanks, and its tanks are made of an aluminum-lithium alloy to save weight.

The Long March 12 is also the first rocket of its size in the Long March family to be assembled on its side instead of stacked vertically on its launch mount. After integrating the rocket in a nearby hangar, technicians transferred the first Long March 12 to its launch pad horizontally, then raised it vertical with an erector system. This is the same way SpaceX integrates and transports Falcon 9 rockets to the launch pad. SpaceX copied this horizontal integration approach from older Soviet-era rockets, and it offers several advantages, allowing teams to assemble rockets faster without the need for large overhead cranes in tall, cavernous vertical assembly buildings.

A bug or a feature?

We’ve already mentioned the proliferation of different types of Long March rockets, with nine classes of Long March launchers currently in operation. And each of these comes in multiple sub-variants.

This is a starkly different approach from SpaceX, which flies standardized rockets like the Falcon 9 and Falcon Heavy, which almost always fly in the same configuration, regardless of the payload or destination for each mission. The only exception is when SpaceX launches Dragon crew or cargo capsules on the Falcon 9.

Depending on how you count them, China now has roughly 18 different types of active space launchers. This number doesn’t include the Long March 9 or Long March 10, but it counts all the other Long March configurations, plus numerous small- and medium-class rockets fielded by China’s quasi-commercial space industry.

These startups operate with the blessing of China’s government and, in many cases, got their start by utilizing surplus military equipment and investment from Chinese local or provincial governments. However, the Chinese Communist Party has allowed them to raise capital from private sources, and they operate on a commercial basis, almost exclusively to serve domestic Chinese markets.

In some cases, these launch startups compete for commercial contracts directly with the government-backed Long March rocket family. The Long March 12 could be in the mix for launching large batches of spacecraft for China’s planned satellite Internet networks.

Some of these launch companies are working on reusable rockets similar in appearance to SpaceX’s Falcon 9. All of these rockets, government and commercial, are part of an ecosystem of Chinese launchers tasked with hauling military and commercial satellites into orbit.

The Long March 12 launch Saturday was China’s 58th orbital launch attempt of 2024, and no single subvariant of a Chinese rocket has flown more than seven times this year. This is in sharp contrast to the United States, which has logged 142 orbital launch attempts so far this year, 119 of them by SpaceX’s Falcon 9 or Falcon Heavy rockets.

There are around a dozen US orbital-class launch vehicle types you might call operational. But a few of these, such as Northrop Grumman’s Pegasus XL and Minotaur, and NASA’s Space Launch System, haven’t flown for several years.

SpaceX’s Falcon 9 is now the dominant leader in the US launch industry. Most of the Falcon 9 launches are filled to capacity with SpaceX’s own Starlink Internet satellites, but many missions fly with their payload fairings only partially full. Still, the Falcon 9 is more affordable on a per-kilogram basis than any other US rocket.

In China, on the other hand, none of the commercial launch startups have emerged as a clear leader. When that happens, if China allows the market to function in a truly commercial manner, some of these Chinese rocket companies will likely fold.

However, China’s government has a strategic interest in maintaining a portfolio of rockets and launch sites, same as the US government. For example, Chinese officials said the new launch site at Wenchang, where the Long March 12 took off from over the weekend, can accommodate 10 or more different types of rockets.

Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.

Over the weekend, China debuted a new rocket on the nation’s path to the Moon Read More »

Supermassive black hole binary emits unexpected flares

astronomy, astrophysics, black hole binary, black holes, Science, supermassive black hole / Tim Belzer / December 1, 2024

“In addition to stars, gas clouds can also be disrupted by SMBHs and their binaries,” they said in the same study. “The key difference is that the clouds can be comparable to or even larger than the binary separation, unlike stars, which are always much smaller. “

Looking at the results of a previous study that numerically modeled this type of situation also suggested a gas cloud. Just like the hypothetical supermassive black hole binary in the model, AT 2021hdr would accrete large amounts of material every time the black holes were halfway through orbiting each other and had to cross the cloud to complete the orbit—their gravity tears away some of the cloud, which ends up in their accretion disks, every time they cross it. They are now thought to take in anywhere between three and 30 percent of the cloud every few cycles. From a cloud so huge, that’s a lot of gas.

The supermassive black holes in AT 2021hdr are predicted to crash into each other and merge in another 70,000 years. They are also part of another merger, in which their host galaxy is gradually merging with a nearby galaxy, which was first discovered by the same team (this has no effect on the BSMBH tidal disruption of the gas cloud).

How the behavior of AT 2021hdr develops could tell us more about its nature and uphold or disprove the idea that it is eating away at a gaseous cloud instead of a star or something else. For now, it seems these black holes don’t just get gas from what they eat—they eat the gas itself.

Astronomy & Astrophysics, 2024. DOI: 10.1051/0004-6361/202451305

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