AI startup Anthropic, writing in a blog post: Neural networks are trained on data, not programmed to follow rules. With each step of training, millions or billions of parameters are updated to make the model better at tasks, and by the end, the model is capable of a dizzying array of behaviors. We understand the math of the trained network exactly -- each neuron in a neural network performs simple arithmetic -- but we don't understand why those mathematical operations result in the behaviors we see. This makes it hard to diagnose failure modes, hard to know how to fix them, and hard to certify that a model is truly safe. Neuroscientists face a similar problem with understanding the biological basis for human behavior. The neurons firing in a person's brain must somehow implement their thoughts, feelings, and decision-making. Decades of neuroscience research has revealed a lot about how the brain works, and enabled targeted treatments for diseases such as epilepsy, but much remains mysterious. Luckily for those of us trying to understand artificial neural networks, experiments are much, much easier to run. We can simultaneously record the activation of every neuron in the network, intervene by silencing or stimulating them, and test the network's response to any possible input.

Unfortunately, it turns out that the individual neurons do not have consistent relationships to network behavior. For example, a single neuron in a small language model is active in many unrelated contexts, including: academic citations, English dialogue, HTTP requests, and Korean text. In a classic vision model, a single neuron responds to faces of cats and fronts of cars. The activation of one neuron can mean different things in different contexts. In our latest paper, Towards Monosemanticity: Decomposing Language Models With Dictionary Learning , we outline evidence that there are better units of analysis than individual neurons, and we have built machinery that lets us find these units in small transformer models. These units, called features, correspond to patterns (linear combinations) of neuron activations. This provides a path to breaking down complex neural networks into parts we can understand, and builds on previous efforts to interpret high-dimensional systems in neuroscience, machine learning, and statistics. In a transformer language model, we decompose a layer with 512 neurons into more than 4000 features which separately represent things like DNA sequences, legal language, HTTP requests, Hebrew text, nutrition statements, and much, much more. Most of these model properties are invisible when looking at the activations of individual neurons in isolation.

A team of scientists drove hundreds of miles through the steppes of Kazakhstan in search of what may be one of the largest and most diverse fungi ecosystems on Earth.

The Washington Post believes their efforts "could help make the planet more resilient to climate change." When these underground fungi come together, they form sophisticated systems known as "mycorrhizal networks...." Mycorrhizal fungi often form mutually beneficial relationships with plants. They trade essential nutrients such as phosphorus and nitrogen in exchange for carbon, and act as an extended root system, allowing plants to access water they can't reach. These networks may also prove to be invaluable for transporting carbon underground, a study published in June found. About 13 gigatons of carbon fixed by vegetation — equivalent to about one-third of all carbon dioxide emissions from fossil fuels in one year — flows through underground fungi, according to an analysis of nearly 200 data sets.

In the steppe, these plant-fungal benefits may be short-lived, however. While deserts are a natural part of Kazakhstan's ecosystem, more than half of the country's vegetation and drylands is at risk of becoming desert as well. The main drivers are large-scale intensive agriculture and increasingly warm and dry temperatures brought by climate change.... Knowing what species of fungi live here is key to understanding how to protect them, said Bethan Manley, project officer at the Society for the Protection of Underground Networks who was on the expedition. It will help determine "where we might be able to have the most effective measures of not poisoning them with fungicides or not having harmful farming practices," she said.

Black Parrot (Slashdot reader #19,622) pointed out a historic anniversary this week: On October 6, 1923, Edwin Hubble got a photo of Andromeda that showed that it contained a variable star, and therefore was an actual galaxy, ending the Great Debate over whether the universe consisted of anything beyond our own galaxy.

Unless you're more than 100 years old you grew up with a completely different understanding of the universe than anyone who lived before. Even Einstein did not know about it when he proposed the theory of general relativity.

It was later in the decade before Hubble discovered that the universe is expanding.
A century later, the European Space Agency was announcing... A very rare, strange burst of extraordinarily bright light in the universe just got even stranger â" thanks to the eagle-eye of the NASA/ESA Hubble Space Telescope. The phenomenon, called a Luminous Fast Blue Optical Transient (LFBOT), flashed onto the scene where it wasnâ(TM)t expected to be found, far away from any host galaxy. Only Hubble could pinpoint its location. The Hubble results suggest astronomers know even less about these objects than previously thought by ruling out some possible theories.
Bill Kendrick (Slashdot reader #19,287) writes: Edwin Hubble's discovery — thanks to a Cepheid Variable star — that the "Andromeda Nebula" was actually an entire galaxy 2.5 million light years away... NASA's Astronomy Photo of the Day for today celebrates this with an image of the original photo plate from October 6, 1923. Notice the "N" (for nova) crossed off, and "VAR!" (for variable) next to the star!

The discovery of Cepheids, and the important fact that their brightening and dimming was regular, and could be used to determine a star's intrinsic brightness, was thanks to Henrietta Swan Leavitt about a decade earlier.

David Butler's "How Far Away Is It?" series has an excellent episode on Andromeda on YouTube.

Slashdot reader TranquilVoid writes: To better understand the battles between native and invasive ants, scientists at Australia's national science agency have turned to Microsoft's classic computer game to model ant warfare.

Across Australia, 50 different species of invasive ants have established themselves, including electric ants, fire ants and yellow crazy ants, with hundreds of millions of dollars spent attempting to eradicate them.

"Ants are one of the few groups of animal species in which warfare resembles human warfare, in terms of scale and mortality," researcher Samuel Lymbery said. The research found small armies of strong soldiers did better in complex terrain-based battlefields and large armies of weaker soldiers fared better in simple open battlefields. In the ant world, a simple battlefield would be a footpath or park while a complex battlefield would be bushland with undergrowth and woody debris.

Dr Lymbery said his work could help develop new approaches to habitat management, like adding undergrowth or more environmental complexity back into urbanised environments, to tip the competitive balance back in favour of native ants.

An announcement from MIT News: One promising approach to treating Type 1 diabetes is implanting pancreatic islet cells that can produce insulin when needed, which can free patients from giving themselves frequent insulin injections. However, one major obstacle to this approach is that once the cells are implanted, they eventually run out of oxygen and stop producing insulin.

To overcome that hurdle, MIT engineers have designed a new implantable device that not only carries hundreds of thousands of insulin-producing islet cells, but also has its own on-board oxygen factory, which generates oxygen by splitting water vapor found in the body. The researchers showed that when implanted into diabetic mice, this device could keep the mice's blood glucose levels stable for at least a month. The researchers now hope to create a larger version of the device, about the size of a stick of chewing gum, that could eventually be tested in people with Type 1 diabetes.

"You can think of this as a living medical device that is made from human cells that secrete insulin, along with an electronic life support-system," says Daniel Anderson, a professor in MIT's Department of Chemical Engineering, a member of MIT's Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science, and the senior author of the study.

While the researchers' main focus is on diabetes treatment, they say that this kind of device could also be adapted to treat other diseases that require repeated delivery of therapeutic proteins.
Thanks to Slashdot reader schwit1 for sharing the news.

Scientists using the H.E.S.S. observatory in Namibia have detected the highest energy gamma rays ever from a dead star called a pulsar. Phys.Org reports: The energy of these gamma rays clocked in at 20 tera-electronvolts, or about 10 trillion times the energy of visible light. This observation is hard to reconcile with the theory of the production of such pulsed gamma rays, as the international team reports in the journal Nature Astronomy. [...] The Vela pulsar, located in the Southern sky in the constellation Vela (sail of the ship), is the brightest pulsar in the radio band of the electromagnetic spectrum and the brightest persistent source of cosmic gamma rays in the giga-electronvolts (GeV) range. It rotates about eleven times per second. However, above a few GeV, its radiation ends abruptly, presumably because the electrons reach the end of the pulsar's magnetosphere and escape from it. But this is not the end of the story: using deep observations with H.E.S.S., a new radiation component at even higher energies has now been discovered, with energies of up to tens of tera-electronvolts (TeV).

"That is about 200 times more energetic than all radiation ever detected before from this object," says co-author Christo Venter from the North-West University in South Africa. This very high-energy component appears at the same phase intervals as the one observed in the GeV range. However, to attain these energies, the electrons might have to travel even farther than the magnetosphere, yet the rotational emission pattern needs to remain intact. "This result challenges our previous knowledge of pulsars and requires a rethinking of how these natural accelerators work," says Arache Djannati-Atai from the Astroparticle & Cosmology (APC) laboratory in France, who led the research. "The traditional scheme according to which particles are accelerated along magnetic field lines within or slightly outside the magnetosphere cannot sufficiently explain our observations. Perhaps we are witnessing the acceleration of particles through the so-called magnetic reconnection process beyond the light cylinder, which still somehow preserves the rotational pattern? But even this scenario faces difficulties to explain how such extreme radiation is produced."

Whatever the explanation, next to its other superlatives, the Vela pulsar now officially holds the record as the pulsar with the highest-energy gamma rays discovered to date. "This discovery opens a new observation window for detection of other pulsars in the tens of teraelectronvolt range with current and upcoming more sensitive gamma-ray telescopes, hence paving the way for a better understanding of the extreme acceleration processes in highly magnetized astrophysical objects," says Djannati-Atai.

An anonymous reader quotes a report from The Conversation: Recently, several mammals have been reported to "glow" under ultraviolet (UV) light, including our beloved platypus. But no one knew how common it was among mammals until now. Our research, published in Royal Society Open Science today, found this glow -- known as fluorescence -- is extremely common. Almost every mammal we studied showed some form of fluorescence. [...] We started with the platypus to see if we could replicate the previously reported fluorescence. We photographed preserved and frozen platypus specimens under UV light and observed a fluorescent (although rather faint) glow. [...] We repeated this process for other mammals and found clear evidence of fluorescence in the white fur, spines and even skin and nails of koalas, Tasmanian devils, short-beaked echidnas, southern hairy-nosed wombats, quendas (bandicoots), greater bilbies and even cats. Both fresh-frozen and chemically treated museum specimens were fluorescent. This meant it wasn't preservation chemicals such as borax or arsenic causing the fluorescence. So, we concluded this was a real biological phenomenon.

Using specimens from the Western Australian Museum's collection, we took the experiment to the next stage. We recorded every species of mammal that was fluorescent when we exposed the specimens to UV light. As a result, we found 125 fluorescent species of mammal, representing all known orders. Fluorescence is clearly common and widely distributed among mammals. In particular, we noticed that white and light-colored fur is fluorescent, with dark pigmentation preventing fluorescence. For example, a zebra's white stripes fluoresced while the dark stripes didn't. We then used our dataset to test if fluorescence might be more common in nocturnal species. To do this, we correlated the total area of fluorescence with ecological traits such as nocturnality, diet and locomotion. Nocturnal mammals were indeed more fluorescent, while aquatic species were less fluorescent than those that burrowed, lived in trees, or on land.

Based on our results, we think fluorescence is very common in mammals. In fact, it is likely the default status of hair unless it is heavily pigmented. This doesn't mean fluorescence has a biological function -- it may just be an artifact of the structural properties of unpigmented hair. However, we suggest florescence may be important for brightening pale-colored parts of animals that are used as visual signals. This could improve their visibility, especially in poor light -- just like the fluorescent optical brighteners that are added to white paper and clothing.

Tom Perkins writes via The Guardian: Almost half of a federal government panel that helps develop US nutritional guidelines has significant ties to big agriculture, ultra-processed food companies, pharmaceutical companies and other corporate organizations with a significant stake in the process's outcome. The revelation is part of a new report from US Right to Know, a government transparency group that looked for ties to corporate interests among the 20-member panel of food and nutrition experts that makes recommendations for updating the US government's official dietary guidelines.

It found nine members had ties to Nestle, Pfizer, Coca-Cola, the National Egg Board and other prominent food lobby groups, among others. The findings raise questions about whether the panel is looking out for Americans' health or corporate profits, and "erodes confidence in dietary guidelines," said Gary Ruskin of US Right to Know. "Millions of Americans' lives are affected by this report and it's crucial that the report tell the truth to American people and it's not degraded into another sales pitch for big food and big pharma," he said. [...]

"The guidelines affect the entire US food system quite strongly," Ruskin said. US Right to Know scoured public records dating back five years for conflicts of interest among the 20 panel members. In addition to the nine it found with "high-risk conflicts of interest" and connections to the food and drug industry, it found four more members who have possible conflicts of interest. It applauded the agencies for appointing seven members who did not appear to have any conflicts. At least four panelists have connections to at least two companies each among Abbott, Novo Nordisk, the National Dairy Council, Eli Lilly and Weight Watchers International. One panel member has received about $240,000 in grant funding from Eli Lilly.

Lawmakers in the United States last year passed bipartisan legislation intended to maintain US competitiveness with countries such as China by boosting funding for science and innovation. But concerns are mounting that the US Congress will fail to deliver on its promises. From a report: The money allotted to a handful of major US science agencies that had been targeted for a budget boost is likely to fall short of the legislation's goals by more than US$7 billion in 2024, according to a report. And overall funding for those agencies will continue to hover at a 25-year low.

"We're leaving scientific opportunities on the table," says Matt Hourihan, who led the analysis for the Federation of American Scientists, an advocacy group based in Washington DC. "If we drop this ball, others will be happy to pick it up." It was precisely this fear that drove members of Congress to come together to pass the CHIPS and Science Act of 2022. The legislation promised one of the largest increases in US science funding in a long time, totalling some $280 billion over five years. Much of the spending mandated by the bill was focused on semiconductor research and manufacturing -- areas in which other countries, particularly China, have dominated. Lawmakers also authorized investments in other science and innovation programmes, but these were not mandated, and need to be approved by Congress during an appropriations process each year.

That process has become increasingly contentious as political polarization in the United States has risen over the past few decades. Disputes about overall spending levels and funding for various social programmes have led to repeated delays in crafting the annual budget, at times forcing the government to shut down. This year is a prime example: Republicans, who control the US House of Representatives, blocked legislation that would have allowed the government to increase the federal debt limit and pay its bills, until they were able to secure an agreement with the Democrats in May to limit spending. And last month, a handful of extreme right-wing Republicans sought to close the government down as they pushed for further spending cuts.

Amazon has launched its first two satellites for its Project Kuiper, the tech giant's initiative to build a massive constellation of satellites that can provide internet coverage to Earth. From a report: An Atlas V rocket, operated by United Launch Alliance, lofted the pair of satellites en route to orbit from Florida at 2:06 p.m. local time Friday. The mission is still ongoing, and it's unclear when the satellites will be deployed from the rocket.

Project Kuiper's goal is to eventually put 3,326 satellites into low Earth orbit, where they will beam broadband internet service to the ground below, similar to Elon Musk's SpaceX Starlink. The two launched Friday, KuiperSat-1 and KuiperSat-2, are test satellites that will allow Amazon to demonstrate the ability to send and receive broadband signals. This mission has been long delayed. Amazon originally hoped to launch these satellites a year ago on a different, experimental rocket. However, the company wound up switching the launch vehicle for these satellites multiple times, eventually landing on ULA's workhorse Atlas V rocket, in order to get the satellites into space more quickly.

Jonathan Josephs & Antoinette Radford reporting via the BBC: Nasa astronauts will be flying in style, with luxury fashion designer Prada helping design space suits for the 2025 moon mission. The Italian fashion house will work to design the suits alongside another private company, Axiom Space. In a press release, Axiom said Prada would bring expertise with materials and manufacturing to the project. One astronaut told the BBC he thought Prada was up to the challenge due to their design experience. That experience has been built not only on the catwalks of Milan but also through Prada's involvement in the America's Cup sailing competition.

"Prada has considerable experience with various types of composite fabrics and may actually be able to make some real technical contributions to the outer layers of the new space suit," according to Professor Jeffrey Hoffman, who flew five Nasa missions and has carried out four spacewalks. But, he said people should not expect to see astronauts in "paisley spacesuits or any fancy patterns like that. Maintaining a good thermal environment is really the critical thing". "A spacesuit is really like a miniature spacecraft. It has to provide pressure, oxygen, keep you at a reasonable temperature," he added.

The global average temperature for September broke records by such an absurd margin that climate experts are struggling to describe the phenomenon. From a report: "This month was -- in my professional opinion as a climate scientist -- absolutely gobsmackingly bananas," Zeke Hausfather, a researcher with Berkeley Earth, said on the social media platforms Bluesky and X. The numbers are stark. September 2023 beat the previous record for the month, set in 2020, by 0.5C (0.9F), according to data sets maintained by the Japan Meteorological Agency and the EU's Copernicus Climate Change Service. The temperature anomaly for the month was roughly 1.7C above pre-industrial levels, which is above the symbolic 1.5C mark set as the stretch goal in the Paris Agreement.

"We've never really seen a jump anything quite of this magnitude," Hausfather said. "Half a degree C is analogous to slightly less than half of all the warming we've seen from pre-industrial [temperatures]." Carbon dioxide emissions from burning fossil fuels are the main driver of rising temperatures. The global average temperature this year has also seen a boost from El Nino, a natural climate shift in the Pacific. Other factors may also be pushing temperatures up incrementally, such as a decline in cooling aerosol pollution from ships. Hausfather said next September may be unlikely to have all the same compounding factors, and consequently may be not as extreme. But either way, he described September 2023 as a "sneak peek" of what the back-to-school month may feel like in a decade as climate change pushes temperatures higher.

Becky Ferreira writes via the New York Times: Last November, a satellite in low-Earth orbit unfurled into an expansive array that extends across nearly 700 square feet, about the size of a studio apartment. The satellite, BlueWalker 3, has since become one of the brightest objects in the sky, outshining some of the most radiant stars in the Milky Way, according to a study published on Monday in Nature -- and it is just the first of dozens of similar satellites that are in development by AST SpaceMobile, a company that aims to keep smartphones connected from orbit. "The issue is not necessarily that one satellite," said Siegfried Eggl, an astrophysicist at the University of Illinois, Urbana-Champaign and an author of the new study, "but that it is a predecessor or prototype of a constellation, so there's going to be a lot of those out there eventually."

Initially launched in September 2022, BlueWalker 3 is the forerunner of AST SpaceMobile's BlueBird satellites, which aim to serve as a network of orbital cell towers with the goal "to democratize access to knowledge and information regardless of where people live and work," a spokesperson for AST SpaceMobile said. Last month, BlueWalker 3 successfully relayed its first 5G connection to a smartphone in a cellular coverage gap on Earth. AST SpaceMobile is one of many companies racing to capture the surging demand for global broadband connectivity. "At the moment, there are 18 constellations that we know are planned all over the world," Dr. Eggl said. "The total number of satellites is a stunning half a million that people are planning to put up there. This is 100 times more than we already have."

AST SpaceMobile made BlueWalker 3's array so large in order to beam strong cellular coverage directly to phones on Earth. The satellite is made of many small antennas that can connect existing smartphones, which is an approach that distinguishes the company from Starlink and other planned constellations that currently rely on ground antennas or dishes. [...] AST SpaceMobile said that it was working with astronomers on techniques to reduce disruptions. It also contrasted the number in its constellation with the tens of thousands planned by other companies. The spokesperson said it could "provide substantial global coverage with around 90 satellites." Though BlueBird satellites would be far fewer in number, they are at least 64 times as big and bright as a Starlink satellite. The SpaceX orbiters are also brightest in the days after their deployment, but they become much fainter once they settle into their target orbits. Astronomers expect that the BlueBird satellites will remain bright in the sky throughout most of their lifetime. As a consequence, one of these satellites could interfere with data captured by astronomical observatories.

Kiley Price writes via Inside Climate News: In a new initiative announced on Tuesday, the U.S. Fish & Wildlife Service is working with the nonprofit Revive & Restore and other partners to create a "genetic library" of the country's endangered species -- before it's too late. Through a process called biobanking, FWS field staff are gathering biological samples such as blood, tissues and reproductive cells from animals to be cryogenically preserved at extremely low temperatures (at least -256 degrees Fahrenheit) and stored at a USDA facility in Colorado. The samples will also be genetically sequenced and this information will be uploaded to a publicly available database called GenBank, where researchers can study them and compare their genomes to other members of their species.

The Nobel Prize in Chemistry was awarded on Wednesday to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov for being pioneers of the nanoworld. The new laureates discovered and developed quantum dots, semiconductors made of particles squeezed so small that their electrons barely have room to breathe. From a report: "For a long time, nobody thought you could ever actually make such small particles," Johan Aqvist, the chair of the Academy's Nobel committee for chemistry, said at the news conference announcing the 2023 laureates. Presenting the topic with five colorful flasks lined up in front of him, which he said contained quantum dots in a liquid solution, he said: "But this year's laureates succeeded."

Several scientists from NASA told the New York Times that the agency is planning to build houses on the moon by 2040. Forbes reports: The agency is set to return to the moon and is hoping its astronauts can stay long-term -- in a house built on the moon via a 3D printer. The idea is to build the house structure out of a special lunar concrete from the moon's surface, and NASA has found just the company to do it: Austin-based 3D printing company, ICON. In what's been dubbed Project Olympus, ICON

ICON created its first 350-square-foot prototype home in Austin in March 2018 with a proprietary machine called Vulcan. This year, it showcased its first model home at Wolf Ranch in Georgetown, Texas, which is part of its 3D-printed 100-home community project. The start-up first received funding from NASA in 2020, and in 2022 it announced an additional $60 million for a space-based construction system that can be used beyond earth. The idea is to send a 3D printer up to the moon via a rocket, and the printer completes its job from there. "We've got all the right people together at the right time with a common goal, which is why I think we'll get there," NASA's director of technology maturation, Niki Werkheiser told The New York Times. "Everyone is ready to take this step together, so if we get our core capabilities developed, there's no reason it's not possible."

The Nobel Prize in Physics was awarded to Pierre Agostini, Ferenc Krausz and Anne L'Huillier on Tuesday for their experiments that "have given humanity new tools for exploring the world of electrons inside atoms and molecules." From a report: Electrons move at a whopping 43 miles a second. This speed long made them impossible to study. The new experimental techniques created by the three scientist-laureates use short light pulses to capture an electron's movement at a single moment in time. Think of a rotating fan at its highest speed: each blade is a blur. But if you point a strobe light at the fan, every flash will illuminate a frozen moment in time. As the flashes get shorter, more information about the fan is revealed.

To study the movement of electrons, the scientists had to use pulses of light that last an attosecond. An attosecond is one quintillionth of a second. The number of attoseconds in a single second is the same as the number of all the seconds that have elapsed since the universe burst into existence 13.8 billion years ago, according to the Royal Swedish Academy of Sciences, which awards the Nobel Prizes. Eva Olsson, the chair of the Nobel Committee for Physics, said at a news conference on Tuesday that attosecond science "allows us to address fundamental questions" such as the time scale of the photoelectric effect, the release of electrons from a material when light shines on it. Albert Einstein received the 1921 Nobel Prize in Physics for his discovery of this effect. Accessing the ultrafast world of electron motion may also lead to advances in electronic circuitry, drug design and the materials used for batteries.

Tablizer shares a report from Space.com: In a solar system called TRAPPIST-1, 40 light years from the sun, seven Earth-sized planets revolve around a cold star. Astronomers obtained new data from the James Webb Space Telescope (JWST) on TRAPPIST-1 b, the planet in the TRAPPIST-1 solar system closest to its star. These new observations offer insights into how its star can affect observations of exoplanets in the habitable zone of cool stars. In the habitable zone, liquid water can still exist on the orbiting planet's surface.

The team, which included University of Michigan astronomer and NASA Sagan Fellow Ryan MacDonald, published its study in the journal The Astrophysical Journal Letters. "Our observations did not see signs of an atmosphere around TRAPPIST-1 b. This tells us the planet could be a bare rock, have clouds high in the atmosphere or have a very heavy molecule like carbon dioxide that makes the atmosphere too small to detect," MacDonald said. "But what we do see is that the star is absolutely the biggest effect dominating our observations, and this will do the exact same thing to other planets in the system.

Todd Shields and Loren Grush reporting via Bloomberg: Dish Network Corp. was fined $150,000 by US regulators for leaving a retired satellite parked in the wrong place in space, reflecting official concern over the growing amount of debris orbiting Earth and the potential for mishaps. The Federal Communications Commission called the action its first to enforce safeguards against orbital debris. "This is a breakthrough settlement, making very clear the FCC has strong enforcement authority and capability to enforce its vitally important space debris rules," Loyaan A. Egal, the agency's enforcement bureau chief, said in a statement.

Dish's EchoStar-7 satellite, which relayed pay-TV signals, ran short of fuel, and the company retired it at an altitude roughly 76 miles (122 kilometers) above its operational orbit. It was supposed to have been parked 186 miles above its operational orbit, the FCC said in an order (PDF). The company admitted it failed to park EchoStar-7 as authorized. It agreed to implement a compliance plan and pay a $150,000 civil penalty, the FCC said.

The return to flight of Europe's Vega C small launch vehicle has slipped to late 2024 after the European Space Agency concluded a rocket motor nozzle needs to be redesigned. From a report: ESA announced Oct. 2 the completion of an independent investigation into an anomaly that took place during a static-fire test of a Zefiro 40 motor June 28. That test was part of efforts to return the Vega C to flight after a December 2022 launch failure blamed on that motor. Giovanni Colangelo, ESA's inspector general and chair of the committee that investigated the incident, said at a briefing that the performance of the motor was "more or less normal" until 39.7 seconds after ignition. At that point, a new throat insert made of carbon-carbon material was expelled from the nozzle, along with other pieces of the nozzle. The motor continued to burn, although at far lower pressures, until the fuel was exhausted.

The test was intended to confirm the performance of the throat insert, which prime contractor Avio had replaced as part of the recommendations into the December 2022 launch failure. That investigation, released in March, concluded that carbon-carbon material from the original supplier, Ukrainian company Yuzhnoye, did not meet specifications. ArianeGroup now supplies the throat insert. At the time ESA hoped to resume Vega C flights by the end of 2023. The June test anomaly was not linked to that launch failure, ESA concluded. "The failure of the test is related to the design of the nozzle that was not upgraded with the change in the carbon-carbon supplier for the throat insert," Colangelo said. The geometry of the new throat insert and its different thermo-mechanical properties contributed to the failure. "The effects had not been identified as critical during the redesign."