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Scientists want to treat complex bone fractures with a bone-healing gun

3D printing, Biology, bone, fractures, medicine, Science / Beth Washington / September 26, 2025

After examining a few candidate formulations, the team found the right material. “We used a biocompatible thermoplastic called polycaprolactone and hydroxyapatite as base materials,” Lee said. Polycaprolactone was chosen because it is an FDA-approved material that degrades in the body within a few months after implantation. The hydroxyapatite, on the other hand, supports bone-tissue regeneration. Lee’s team experimented with various proportions of these two ingredients and finally nailed the formulation that checked all the boxes: It extruded at a relatively harmless 60° Celsius, the mix was mechanically sound, it adhered to the bone well, and it degraded over time.

Once the bone-healing bullets were ready, the team tested them on rabbits. Rabbits with broken femurs treated with Lee’s healing gun recovered faster than those treated with bone cement, which is the closest commercially available alternative. But there is still a lot to do before the healing gun can be tested on humans.

Skill issues

While the experiment on rabbits revealed new bone tissues forming around the implants created with the healing gun, their slow degradation of the implanted material prevented the full restoration of bone tissues. Another improvement Lee plans involves adding antibiotics to the formulation. The implant, he said, will release the drugs over time to prevent infections.

Then there’s the issue of load bearing. Rabbits are fine as test subjects, but they are rather light. “To evaluate the potential to use this technology on humans, we need to look into its long-term safety in large animal models,” Lee said.

Beyond the questions about the material, the level of skill required to operate this healing gun seems rather high.

Extrusion-based 3D printers, the ones that work more or less like very advanced hot glue guns, usually use guiding rods or rails for precise printing head positioning. If those rods or rails are warped, even slightly, the accuracy of your prints will most likely suffer. Achieving comparable precision with a handheld device might be a bit difficult, even for a skilled surgeon. “It is true that the system requires practice,” Lee said. “We may need to integrate it with a guiding mechanism that would position the head of the device precisely. This could be our next-gen bone printing device.”

Device, 2025. DOI: 10.1016/j.device.2025.100873

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50+ scientific societies sign letter objecting to Trump executive order

Grant funding, grant review process, Policy, Science, Science policy / Mike M. / September 26, 2025

Last month, the Trump administration issued an executive order asserting political control over grant funding, including all federally supported research. In general, the executive order inserts a layer of political control over both the announcement of new funding opportunities and the approval of individual grants. Now, a coalition of more than 50 scientific and medical organizations is firing back, issuing a letter to the US Congress expressing grave concerns over the order’s provisions and urging Congress to protect the integrity of what has long been an independent, merit-based, peer-review system for awarding federal grants.

As we previously reported, the order requires that any announcement of funding opportunities be reviewed by the head of the agency or someone they designate, which means a political appointee will have the ultimate say over what areas of science the US funds. Individual grants will also require clearance from a political appointee and “must, where applicable, demonstrably advance the President’s policy priorities.”

The order also instructs agencies to formalize the ability to cancel previously awarded grants at any time if they’re considered “no longer advance agency priorities.” Until a system is in place to enforce the new rules, agencies are forbidden from starting new funding programs.

In short, the new rules would mean that all federal science research would need to be approved by a political appointee who may have no expertise in the relevant areas, and the research can be canceled at any time if the political winds change. It would mark the end of a system that has enabled US scientific leadership for roughly 70 years.

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Fiji’s ants might be the canary in the coal mine for the insect apocalypse

ants, Biology, evolution, Fiji, insects, Science, speciation / Beth Washington / September 26, 2025

A new genetic technique lets museum samples track population dynamics.

In late 2017, a study by Krefeld Entomological Society looked at protected areas across Germany and discovered that two-thirds of the insect populations living in there had vanished over the last 25 years. The results spurred the media to declare we’re living through an “insect apocalypse,” but the reasons behind their absence were unclear. Now, a joint team of Japanese and Australian scientists have completed a new, multi-year study designed to get us some answers.

Insect microcosm

“In our work, we focused on ants because we have systematic ways for collecting them,” says Alexander Mikheyev, an evolutionary biologist at the Australian National University. “They are also a group with the right level of diversity, where you have enough species to do comparative studies.” Choosing the right location, he explained, was just as important. “We did it in Fiji, because Fiji had the right balance between isolation—which gave us a discrete group of animals to study—but at the same time was diverse enough to make comparisons,” Mikheyev adds.

Thus, the Fijian archipelago, with its 330 islands, became the model the team used to get some insights into insect population dynamics. A key difference from the earlier study was that Mikheyev and his colleagues could look at those populations across thousands of years, not just the last 25.

“Most of the previous studies looked at actual observational data—things we could come in and measure,” Mikheyev explains. The issue with those studies was that they could only account for the last hundred years or so, because that’s how long we have been systematically collecting insect samples. “We really wanted to understand what happened in the longer time frame,” Mikheyev says.

To do this, his team focused on community genomics—studying the collective genetic material of entire groups of organisms. The challenge is that this would normally require collecting thousands of ants belonging to hundreds of species across the entire Fijian archipelago. Given that only a little over 100 out of 330 islands in Fiji are permanently inhabited, this seemed like an insurmountable challenge.

To go around it, the team figured they could run its tests on ants already collected in Fijian museums. But that came with its own set of difficulties.

DNA pieces

Unfortunately, the quality of DNA that could be obtained from museum collections was really bad. From the perspective of DNA preservation, the ants were obtained and stored in horrific conditions, since the idea was to showcase them for visitors, not run genetic studies. “People were catching them in malaise traps,” Mikheyev says. “A malaise trap is basically a bottle of alcohol that sits somewhere in Fiji for a month. Those samples had horribly fragmented, degraded DNA.”

To work with this degraded genetic material, the team employed a technique they called high-throughput museumomics, a relatively new technique that looks at genetic differences across a genome without sequencing the whole thing. DNA sampled from multiple individuals was cut and marked with unique tags at the same repeated locations, a bit like using bookmarks to pinpoint the same page or passage in different issues of the same book. Then, the team sequenced short DNA fragments following the tag to look for differences between them, allowing them to evaluate the genetic diversity within a population. “We developed a series of methods that actually allowed us to harness these museum-grade specimens for population genetics,” Mikheyev explains.

But the trouble didn’t end there. Differences among Fijian ant taxa are based on their appearance, not genetic analysis. For years, researchers were collecting various ants and determining their species by looking at them. This led to 144 species belonging to 40 genera. For Mikheyev’s team, the first step was to look at the genomes in the samples and see if these species divisions were right. It turned out that they were mostly correct, but some species had to be split, while others were lumped together. At the end, the team confirmed that 127 species were represented among their samples.

Overall, the team analyzed more than 4,000 specimens of ants collected over the past decade or so. And gradually, a turbulent history of Fijian ants started to emerge from the data.

The first colonists

The art of reconstructing the history of entire populations from individual genetic sequences relies on comparing them to each other thoroughly and running a whole lot of computer simulations. “We had multiple individuals per population,” Mikheyev explains. “Let’s say we look at this population and find it has essentially no diversity. It suggests that it very recently descended from a small number of individuals.” When the contrary was true and the diversity was high, the team assumed it indicated the population had been stable for a long time.

With the DNA data in hand, the team simulated how populations of ants would evolve over thousands of years under various conditions, and picked scenarios that best matched the genetic diversity results it obtained from real ants. “We identified multiple instances of colonization—broadscale evolutionary events that gave rise to the Fijian fauna that happened in different timeframes,” Mikheyev says. There was a total of at least 65 colonization events.

The first ants, according to Mikheyev, arrived at Fiji millions of years ago and gave rise to 88 endemic Fijian ant species we have today. These ants most likely evolved from a single ancestor and then diverged from their mainland relatives. Then, a further 23 colonization events introduced ants that were native to a broader Pacific region. These ants, the team found, were a mixture of species that colonized Fiji naturally and ones that were brought by the first human settlers, the Lapita people, who arrived around 3,000 years ago.

The arrival of humans also matched the first declines in endemic Fijian ant species.

Slash and burn

“In retrospect, these declines are not really surprising,” Mikheyev says. The first Fijian human colonists didn’t have the same population density as we have now, but they did practice things like slash-and-burn agriculture, where forests were cut down, left to dry, and burned to make space for farms and fertilize the soil. “And you know, not every ant likes to live in a field, especially the ones that evolved to live in a forest,” Mikheyev adds. But the declines in Fijian endemic ant species really accelerated after the first contact with the Europeans.

The first explorers in the 17th and 18th centuries, like Abel Tasman and James Cook, charted some of the Fijian islands but did not land there. The real apocalypse for Fijian ants began in the 19th century, when European sandalwood traders started visiting the archipelago on a regular basis and ultimately connected it to the global trade networks.

Besides the firearms they often traded for sandalwood with local chiefs, the traders also brought fire ants. “Fire ants are native to Latin America, and it’s a common invasive species extremely well adapted to habitats we create: lawns or clear-cut fields,” Mikheyev says. Over the past couple of centuries, his team saw a massive increase in fire ant populations, combined with accelerating declines in 79 percent of endemic Fijian ant species.

Signs of apocalypse

To Mikheyev, Fiji was just a proving ground to test the methods of working with museum-grade samples. “Now we know this approach works and we can start leveraging collections found in museums around the world—all of them can tell us stories about places where they were collected,” Mikheyev says. His ultimate goal is to look for the signs of the insect apocalypse, or any other apocalypse of a similar kind, worldwide.

But the question is whether what’s happening is really that bad? After all, not all ants seem to be in decline. Perhaps what we see is just a case of a better-adapted species taking over—natural selection happening before our eyes?

“Sure, we can just live with fire ants all along without worrying about the kind of beautiful biodiversity that evolution has created on Fiji,” Mikheyev says. “But I feel like if we just go with that philosophy, we’re really going to be irreparably losing important and interesting parts of our ecology.” If the current trends persist, he argues, we might lose endemic Fijian ants forever. “And this would make our world worse, in many ways,” Mikheyev says.

Science, 2025. DOI: 10.1126/science.ads3004

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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DeepMind’s robotic ballet: An AI for coordinating manufacturing robots

AI, Computer science, deepmind, Google, manufacturing, robotics, Science / Kelly Newman / September 25, 2025

An AI figures out how robots can get jobs done without getting in each other’s way.

A lot of the stuff we use today is largely made by robots—arms with multiple degrees of freedom positioned along conveyor belts that move in a spectacle of precisely synchronized motions. All this motion is usually programmed by hand, which can take hundreds to thousands of hours. Google’s DeepMind team has developed an AI system called RoboBallet that lets manufacturing robots figure out what to do on their own.

Traveling salesmen

Planning what manufacturing robots should do to get their jobs done efficiently is really hard to automate. You need to solve both task allocation and scheduling—deciding which task should be done by which robot in what order. It’s like the famous traveling salesman problem on steroids. On top of that, there is the question of motion planning; you need to make sure all these robotic arms won’t collide with each other or with all the gear standing around them.

At the end, you’re facing myriad possible combinations where you’ve got to solve not one but three computationally hard problems at the same time. “There are some tools that let you automate motion planning, but task allocation and scheduling are usually done manually,” says Matthew Lai, a research engineer at Google DeepMind. “Solving all three of these problems combined is what we tackled in our work.”

Lai’s team started by generating simulated samples of what are called work cells, areas where teams of robots perform their tasks on a product being manufactured. The work cells contained something called a workpiece, a product on which the robots do work, in this case something to be constructed of aluminum struts placed on a table. Around the table, there were up to eight randomly placed Franka Panda robotic arms, each with 7 degrees of freedom, that were supposed to complete up to 40 tasks on a workpiece. Every task required a robotic arm’s end effector to get within 2.5 centimeters of the right spot on the right strut, approached from the correct angle, then stay there, frozen, for a moment. The pause simulates doing some work.

To make things harder, the team peppered every work cell with random obstacles the robots had to avoid. “We chose to work with up to eight robots, as this is around the sensible maximum for packing robots closely together without them blocking each other all the time,” Lai explains. Forcing the robots to perform 40 tasks on a workpiece was also something the team considered representative of what’s required at real factories.

A setup like this would be a nightmare to tackle using even the most powerful reinforcement-learning algorithms. Lai and his colleagues found a way around it by turning it all into graphs.

Complex relationships

Graphs in Lai’s model comprised nodes and edges. Things like robots, tasks, and obstacles were treated as nodes. Relationships between them were encoded as either one- or bi-directional edges. One-directional edges connected robots with tasks and obstacles because the robots needed information about where the obstacles were and whether the tasks were completed or not. Bidirectional edges connected the robots to each other, because each robot had to know what other robots were doing at each time step to avoid collisions or duplicating tasks.

To read and make sense of the graphs, the team used graph neural networks, a type of artificial intelligence designed to extract relationships between the nodes by passing messages along the edges of the connections among them. This decluttered the data, allowing the researchers to design a system that focused exclusively on what mattered most: finding the most efficient ways to complete tasks while navigating obstacles. After a few days of training on randomly generated work cells using a single Nvidia A100 GPU, the new industrial planning AI, called RoboBallet, could lay out seemingly viable trajectories through complex, previously unseen environments in a matter of seconds.

Most importantly, though, it scaled really well.

Economy of scale

The problem with applying traditional computational methods to complex problems like managing robots at a factory is that the challenge of computation grows exponentially with the number of items you have in your system. Computing the most optimal trajectories for one robot is relatively simple. Doing the same for two is considerably harder; when the number grows to eight, the problem becomes practically intractable.

With RoboBallet, the complexity of computation also grew with the complexity of the system, but at a far slower rate. (The computations grew linearly with the growing number of tasks and obstacles, and quadratically with the number of robots.) According to the team, these computations should make the system feasible for industrial-scale use.

The team wanted to test, however, whether the plans their AI was producing were any good. To check that, Lai and his colleagues computed the most optimal task allocations, schedules, and motions in a few simplified work cells and compared those with results delivered by RoboBallet. In terms of execution time, arguably the most important metric in manufacturing, the AI came very close to what human engineers could do. It wasn’t better than they were—it just provided an answer more quickly.

The team also tested RoboBallet plans on a real-world physical setup of four Panda robots working on an aluminum workpiece, and they worked just as well as in simulations. But Lai says it can do more than just speed up the process of programming robots.

Limping along

RoboBallet, according to DeepMind’s team, also enables us to design better work cells. “Because it works so fast, it would be possible for a designer to try different layouts and different placement or selections of robots in almost real time,” Lai says. This way, engineers at factories would be able to see exactly how much time they would save by adding another robot to a cell or choosing a robot of a different type. Another thing RoboBallet can do is reprogram the work cell on the fly, allowing other robots to fill in when one of them breaks down.

Still, there are a few things that still need ironing out before RoboBallet can come to factories. “There are several simplifications we made,” Lai admits. The first was that the obstacles were decomposed into cuboids. Even the workpiece itself was cubical. While this was somewhat representative of the obstacles and equipment in real factories, there are lots of possible workpieces with more organic shapes. “It would be better to represent those in a more flexible way, like mesh graphs or point clouds,” Lai says. This, however, would likely mean a drop in RoboBallet’s blistering speed.

Another thing is that the robots in Lai’s experiments were identical, while in a real-world work cell, robotic teams are quite often heterogeneous. “That’s why real-world applications would require additional research and engineering specific to the type of application,” Lai says. He adds, though, that the current RoboBallet is already designed with such adaptations in mind—it can be easily extended to support them. And once that’s done, his hope is that it will make factories faster and way more flexible.

“The system would have to be given work cell models, the workpiece models, as well as the list of tasks that need to be done—based on that, RoboBallet would be able to generate a complete plan,” Lai says.

Science Robotics, 2025. DOI: 10.1126/scirobotics.ads1204

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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Judge lets construction on an offshore wind farm resume

injunction, lawsuit, offshore wind, renewable energy, Science, trump administration, wind power / DJ Henderson / September 23, 2025

That did not, however, stop the administration from trying again, this time targeting a development called Revolution Wind, located a bit further north along the Atlantic coast. This time, however, the developer quickly sued, leading to Monday’s ruling. According to Reuters, after a two-hour court hearing at the District Court of DC, Judge Royce Lamberth termed the administration’s actions “the height of arbitrary and capricious” and issued a preliminary injunction against the hold on Revolution Wind’s construction. As a result, Orsted can restart work immediately.

The decision provides a strong indication of how Lamberth is likely to rule if the government pursues a full trial on the case. And while the Trump administration could appeal, it’s unlikely to see this injunction lifted unless it takes the case all the way to the Supreme Court. Given that Revolution Wind was already 80 percent complete, the case may become moot before it gets that far.

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What climate targets? Top fossil fuel producing nations keep boosting output

climate change, fossil fuels, paris agreement, Science, syndication / Beth Washington / September 22, 2025

Top producers are planning to mine and drill even more of the fuels in 2030.

Machinery transfers coal at a port in China’s Chongqing municipality on April 20. Credit: STR/AFP via Getty Images

The last two years have witnessed the hottest one in history, some of the worst wildfire seasons across Canada, Europe and South America and deadly flooding and heat waves throughout the globe. Over that same period, the world’s largest fossil fuel producers have expanded their planned output for the future, setting humanity on an even more dangerous path into a warmer climate.

Governments now expect to produce more than twice as much coal, oil and gas in 2030 as would be consistent with the goals of the Paris Agreement, according to a report released Monday. That level is slightly higher than what it was in 2023, the last time the biennial Production Gap report was published.

The increase is driven by a slower projected phaseout of coal and higher outlook for gas production by some of the top producers, including China and the United States.

“The Production Gap Report has long served as a mirror held up to the world, revealing the stark gap between fossil fuel production plans and international climate goals,” said Christiana Figueres, former executive secretary of the United Nations Framework Convention on Climate Change, in a foreword to the report. “This year’s findings are especially alarming. Despite record climate impacts, a winning economic case for renewables, and strong societal appetite for action, governments continue to expand fossil fuel production beyond what the climate can withstand.”

The peer-reviewed report, written by researchers at the Stockholm Environment Institute, Climate Analytics and the International Institute for Sustainable Development, aims to focus attention on the supply side of the climate equation and the government policies that encourage or steer fossil fuel production.

“Governments have such a significant role in setting up the rules of the game,” said Neil Grant, a senior expert at Climate Analytics and one of the authors, in a briefing for reporters. “What this report shows is most governments are not using that influence for good.”

Chart showing growth in fossil fuel production — Credit: Inside Climate News

The report’s blaring message is that these subsidies, tax incentives, permitting and other policies have largely failed to adapt to the climate targets nations have adopted. The result is a split screen. Governments say they will cut their own climate-warming pollution, yet they plan to continue producing the fossil fuels that are driving that pollution far beyond what their climate targets would allow.

The report singles out the United States as “the starkest case of a country recommitting to fossil fuels.” The data for the United States, which draws on the latest projections of the US Energy Information Administration, does not reflect most of the policies the Trump administration and Congress have put in place this year to promote fossil fuels.

Since January, Congress has enacted billions of dollars in new subsidies to oil and gas companies while the Trump administration has forced retiring coal plants to continue operating, expanded mining and drilling access on public lands, delayed deadlines for drillers to comply with limits on methane pollution and fast-tracked fossil fuel permitting while setting roadblocks for building wind and solar energy projects.

In response to the report, White House spokesperson Taylor Rogers said in an email, “As promised, President Trump ended Joe Biden’s war on American energy and unleashed American energy on day one in the best interest of our country’s economic and national security. He will continue to restore American’s energy dominance.”

Chart showing planned fuel production — Credit: Inside Climate News

The Production Gap report assessed the government plans or projections of 20 of the world’s top producers. Some have state-owned enterprises while others are dominated by publicly listed companies. The countries, which were chosen for their production levels, availability of data and presence of clear climate targets, account for more than 80 percent of fossil fuel output. The report models total global production by scaling the data up to account for the rest.

All but three of the 20 nations are planning or projecting increased production in 2030 of at least one fossil fuel. Eleven now project higher production of at least one fuel in 2030 than they did two years ago.

Expected global output of coal, oil, and gas for 2030 is now 120 percent more than what would be consistent with pathways to limit warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) and 77 percent higher than scenarios to keep warming to less than 2 degrees Celsius (3.6 degrees Fahrenheit). The greater the warming, the more severe the consequences will be on extreme weather, rising seas and other impacts.

While previous installments of the report were published under the auspices of the United Nations Environment Program, this year’s version was issued independently.

In a sign of the world’s continuing failure to limit fossil fuel use, the modeling scenarios the report uses are becoming obsolete. Because nations have continued to burn more coal, gas and oil every year, future cuts would now need to be even steeper than what is reflected in the report to keep climate targets within reach.

“We’re already going into sort of the red and burning up our debt,” Grant said.

Three nations alone—China, the United States and Russia—were responsible for more than half of “extraction-based” emissions in 2022, or the pollution that comes when the fossil fuels are burned.

Ira Joseph, a senior research associate at the Center on Global Energy Policy at Columbia University, who was not involved in the report, said its focus on supply highlights an important part of understanding global energy markets.

“Any type of tax breaks or subsidies or however you want to call them lowers the break-even cost for producing oil and gas,” Joseph said. Lower costs mean more supply, which in turn lowers prices and spurs more demand. The projections and plans the report is based on, Joseph said, reflect this global give and take.

Chart showing fossil fuel increase by country — Credit: Inside Climate News

The biggest changes since the last report come from a slower projected decline in China’s coal mining and faster expected growth in gas production in the United States. Smaller producers are also expecting sharper increases in gas output.

The report did highlight some bright spots. Two additional governments—Brazil and Colombia—are developing plans that would align fossil fuel production with climate goals, bringing the total to six out of the 20. Germany now expects a more accelerated phase-out of coal production. China is speeding its deployment of wind and solar energy. Some countries have also reduced subsidies for fossil fuels.

Yet these measures clearly fall far short, the report said.

The authors called on governments to coordinate their policies and plan for how they can collectively lower production in a way that keeps climate targets within reach without shocking the economies that depend on the jobs and revenue provided by mining, drilling, and processing the fuels. They pointed to a handful of efforts—called Just Energy Transition Partnerships—to provide financing from wealthy countries to support phasing out coal in developing or emerging economies. These programs have struggled to mobilize much money, however, and the Trump administration has withdrawn the United States from them.

Grant said the policies indicate that government officials are failing to adapt to a more uncertain future.

“Change doesn’t happen in straight lines, but I think if you look at the Production Gap report this year, what you see is that many governments are still thinking in straight lines,” Grant said.

The policies the team examined foresee fossil fuel use remaining steady or declining gradually. The result, Grant argued, could be one of two scenarios: Either fossil fuel use remains high for years, in line with these production plans, or it declines more quickly and governments are unprepared for the sudden drop in sales.

“Those would lead to either climate chaos or significant negative economic impacts on countries,” Grant said. “So we need to try to avoid both of those. And the way to do that is to try to align our fossil fuel production plans with our climate goals.”

This story originally appeared on Inside Climate News.

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Despite congressional threat, National Academies releases new climate report

climate change, doe, EPA, greenhouse gasses, National Academies, Science / Shannon Garcia / September 21, 2025

The National Academies responded to the EPA’s actions by saying it would prepare a report of its own, which it did despite the threat of a congressional investigation into its work. And the result undercuts the EPA’s claims even further.

Blunt and to the point

The NAS report does not mess around with subtleties, going straight to the main point: Everything we’ve learned since the endangerment finding confirms that it was on target. “EPA’s 2009 finding that the human-caused emissions of greenhouse gases threaten human health and welfare was accurate, has stood the test of time, and is now reinforced by even stronger evidence,” its authors conclude.

That evidence includes a better understanding of the climate itself, with the report citing “Longer records, improved and more robust observational networks, and analytical and methodological advances” that have both allowed us to better detect the changes in the climate, and more reliably assign them to the effects of greenhouse gases. The events attributed to climate change are also clearly harming the welfare of the US public through things like limiting agricultural productivity gains, damage from wildfires, losses due to water scarcity, and general stresses on our infrastructure.

But it’s not just the indirect effects we have to worry about. The changing climate is harming us more directly as well:

Climate change intensifies risks to humans from exposures to extreme heat, ground-level ozone, airborne particulate matter, extreme weather events, and airborne allergens, affecting incidence of cardiovascular, respiratory, and other diseases. Climate change has increased exposure to pollutants from wildfire smoke and dust, which has been linked to adverse health effects. The increasing severity of some extreme events has contributed to injury, illness, and death in affected communities. Health impacts related to climate-sensitive infectious diseases—such as those carried by insects and contaminated water—have increased.

Moreover, it notes that one of the government’s arguments—that US emissions are too small to be meaningful—doesn’t hold water. Even small increments of change will increase the risk of damaging events for decades to come, and push the world closer to hitting potential tipping points in the climate system. Therefore, cutting US emissions will directly reduce those risks.

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Science journalists find ChatGPT is bad at summarizing scientific papers

AI, journalism, Science, summaries / 9u50fv / September 21, 2025

No, I don’t think this machine summary can replace my human summary, now that you ask… Credit: AAAS

Still, the quantitative survey results among those journalists were pretty one-sided. On the question of whether the ChatGPT summaries “could feasibly blend into the rest of your summary lineups, the average summary rated a score of just 2.26 on a scale of 1 (“no, not at all”) to 5 (“absolutely”). On the question of whether the summaries were “compelling,” the LLM summaries averaged just 2.14 on the same scale. Across both questions, only a single summary earned a “5” from the human evaluator on either question, compared to 30 ratings of “1.”

Not up to standards

Writers were also asked to write out more qualitative assessments of the individual summaries they evaluated. In these, the writers complained that ChatGPT often conflated correlation and causation, failed to provide context (e.g., that soft actuators tend to be very slow), and tended to overhype results by overusing words like “groundbreaking” and “novel” (though this last behavior went away when the prompts specifically addressed it).

Overall, the researchers found that ChatGPT was usually good at “transcribing” what was written in a scientific paper, especially if that paper didn’t have much nuance to it. But the LLM was weak at “translating” those findings by diving into methodologies, limitations, or big picture implications. Those weaknesses were especially true for papers that offered multiple differing results, or when the LLM was asked to summarize two related papers into one brief.

This AI summary just isn’t compelling enough for me. Credit: AAAS

While the tone and style of ChatGPT summaries were often a good match for human-authored content, “concerns about the factual accuracy in LLM-authored content” were prevalent, the journalists wrote. Even using ChatGPT summaries as a “starting point” for human editing “would require just as much, if not more, effort as drafting summaries themselves from scratch” due to the need for “extensive fact-checking,” they added.

These results might not be too surprising given previous studies that have shown AI search engines citing incorrect news sources a full 60 percent of the time. Still, the specific weaknesses are all the more glaring when discussing scientific papers, where accuracy and clarity of communication are paramount.

In the end, the AAAS journalists concluded that ChatGPT “does not meet the style and standards for briefs in the SciPak press package.” But the white paper did allow that it might be worth running the experiment again if ChatGPT “experiences a major update.” For what it’s worth, GPT-5 was introduced to the public in August.

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In a win for science, NASA told to use House budget as shutdown looms

budget, NASA, Science, Space / Beth Washington / September 20, 2025

The situation with the fiscal year 2026 budget for the United States is, to put it politely, kind of a mess.

The White House proposed a budget earlier this year with significant cuts for a number of agencies, including NASA. In the months since then, through the appropriations process, both the House and Senate have proposed their own budget templates. However, Congress has not passed a final budget, and the new fiscal year begins on October 1.

As a result of political wrangling over whether to pass a “continuing resolution” to fund the government before a final budget is passed, a government shutdown appears to be increasingly likely.

Science saved, sort of

In the event of a shutdown, there has been much uncertainty about what would happen to NASA’s budget and the agency’s science missions. Earlier this summer, for example, the White House directed science mission leaders to prepare “closeout plans” for about two dozen spacecraft.

These science missions were targeted for cancellation under the president’s budget request for fiscal year 2026, and the development of these closeout plans indicated that, in the absence of a final budget from Congress, the White House could seek to end these (and other) programs beginning October 1.

However, two sources confirmed to Ars on Friday afternoon that interim NASA Administrator Sean Duffy has now directed the agency to work toward the budget level established in the House Appropriations Committee’s budget bill for the coming fiscal year. This does not support full funding for NASA’s science portfolio, but it is far more beneficial than the cuts sought by the White House.

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Chimps consume alcohol equivalent of nearly 2 drinks a day

animal behavior, Biology, Science / Shannon Garcia / September 20, 2025

Nearly two drinks a day

This latest study involved chimp populations at the Ngogo Chimpanzee Project (Uganda) and a second site at Tai (Ivory Coast), where scientists have estimated the animals consume between 5 to 10 percent of their body weight (about 40 kilos) in fruit each day—around 45 kilograms. The authors collected fallen fruit pulp samples from both sites, packed them in airtight containers, and froze them back at base camp to keep the fruit from ripening further.

Then they quantified the ethanol concentrations using a breathalyzer, a portable gas chromatograph, and chemical testing. The Uganda fruit contained 0.32 percent ethanol, while the Ivory Coast fruit contained 0.31 percent ethanol, which might not sound like much until you consider just how much fruit they eat. And the most frequently consumed fruit at both sites had the highest ethanol content.

If anything, this is a conservative estimate, per Dudley. “If the chimps are randomly sampling ripe fruit, then that’s going to be their average consumption rate, independent of any preference for ethanol,” he said. “But if they are preferring riper and/or more sugar-rich fruits, then this is a conservative lower limit for the likely rate of ethanol ingestion.” That’s in keeping with a 2016 report that captive aye-ayes and slow lorises prefer nectar with the highest alcohol content.

“Our findings imply that our ancestors were similarly chronically exposed to dietary alcohol,” co-author Aleksey Maro, a graduate student at UC Berkeley, told New Scientist. “The drunken monkey hypothesis suggests that this exposure caused our species to evolve an association between alcohol consumption and the reward of finding fruit sugars, and explains human attraction to alcohol today.” One caveat is that apes ingest ethanol accidentally, while humans drink it deliberately.

“What we’re realizing from this work is that our relationship with alcohol goes deep back into evolutionary time, probably about 30 million years,” University of St. Andrews primatologist Catherine Hobaiter, who was not involved with the study, told BBC News. “Maybe for chimpanzees, this is a great way to create social bonds, to hang out together on the forest floor, eating those fallen fruits.”

The next step is to sample the chimps’ urine to see if it contains any alcohol metabolites, as was found in a 2022 study on spider monkeys. This will further refine estimates for how much ethanol-laden fruit the chimps eat every day. Maro spent this summer in Ngogo, sleeping in trees—protected from the constant streams by an umbrella—to collect urine samples.

Science Advances, 2025. DOI: 10.1126/sciadv.adw1665 (About DOIs).

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Meet the 2025 Ig Nobel Prize winners

agriculture, animal behavior, animal husbandry, chemistry, engineering, food additives, Ig Nobel Prizes, language, pediatrics, Physics, psychology, Science / Shannon Garcia / September 19, 2025

The annual award ceremony features miniature operas, scientific demos, and the 24/7 lectures.

The Ig Nobel Prizes honor “achievements that first make people laugh and then make them think.” Credit: Aurich Lawson / Getty Images

Does alcohol enhance one’s foreign language fluency? Do West African lizards have a preferred pizza topping? And can painting cows with zebra stripes help repel biting flies? These and other unusual research questions were honored tonight in a virtual ceremony to announce the 2025 recipients of the annual Ig Nobel Prizes. Yes, it’s that time of year again, when the serious and the silly converge—for science.

Established in 1991, the Ig Nobels are a good-natured parody of the Nobel Prizes; they honor “achievements that first make people laugh and then make them think.” The unapologetically campy awards ceremony features miniature operas, scientific demos, and the 24/7 lectures whereby experts must explain their work twice: once in 24 seconds and the second in just seven words.

Acceptance speeches are limited to 60 seconds. And as the motto implies, the research being honored might seem ridiculous at first glance, but that doesn’t mean it’s devoid of scientific merit. In the weeks following the ceremony, the winners will also give free public talks, which will be posted on the Improbable Research website.

Without further ado, here are the winners of the 2025 Ig Nobel prizes.

Biology

Example of the area of legs and body used to count biting flies on cows. — Credit: Tomoki Kojima et al., 2019

Citation: Tomoki Kojima, Kazato Oishi, Yasushi Matsubara, Yuki Uchiyama, Yoshihiko Fukushima, Naoto Aoki, Say Sato, Tatsuaki Masuda, Junichi Ueda, Hiroyuki Hirooka, and Katsutoshi Kino, for their experiments to learn whether cows painted with zebra-like striping can avoid being bitten by flies.

Any dairy farmer can tell you that biting flies are a pestilent scourge for cattle herds, which is why one so often sees cows throwing their heads, stamping their feet, flicking their tails, and twitching their skin—desperately trying to shake off the nasty creatures. There’s an economic cost as well since it causes the cattle to graze and feed less, bed down for shorter times, and start bunching together, which increases heat stress and risks injury to the animals. That results in less milk yield for dairy cows and less beef yields from feedlot cattle.

You know who isn’t much bothered by biting flies? The zebra. Scientists have long debated the function of the zebra’s distinctive black-and-white striped pattern. Is it for camouflage? Confusing potential predators? Or is it to repel those pesky flies? Tomoki Kojima et al. decided to put the latter hypothesis to the test, painting zebra stripes on six pregnant Japanese black cows at the Aichi Agricultural Research Center in Japan. They used water-borne lacquers that washed away after a few days, so the cows could take turns being in three different groups: zebra stripes, just black stripes, or no stripes (as a control).

The results: the zebra stripes significantly decreased both the number of biting flies on the cattle and the animals’ fly-repelling behaviors compared to those with black stripes or no stripes. The one exception was for skin twitching—perhaps because it is the least energy intensive of those behaviors. Why does it work? The authors suggest it might have something to do with modulation brightness or polarized light that confuses the insects’ motion detection system, used to control their approach when landing on a surface. But that’s a topic for further study.

Chemistry

Freshly cooked frozen w:blintzes in a non-stick frying pan coated with Teflon — Credit: Andrevan/CC BY-SA 2.5

Citation: Rotem Naftalovich, Daniel Naftalovich, and Frank Greenway, for experiments to test whether eating Teflon [a form of plastic more formally called “polytetrafluoroethylene”] is a good way to increase food volume and hence satiety without increasing calorie content.

Diet sodas and other zero-calorie drinks are a mainstay of the modern diet, thanks to the development of artificial sweeteners whose molecules can’t be metabolized by the human body. The authors of this paper are intrigued by the notion of zero-calorie foods, which they believe could be achieved by increasing the satisfying volume and mass of food without increasing the calories. And they have just the additive for that purpose: polytetrafluoroethylene (PTFE), more commonly known as Teflon.

Yes, the stuff they use on nonstick cookware. They insist that Teflon is inert, heat-resistant, impervious to stomach acid, tasteless, cost-effective, and available in handy powder form for easy mixing into food. They recommend a ratio of three parts food to one part Teflon powder.

The authors understand that to the average layperson, this is going to sound like a phenomenally bad idea—no thank you, I would prefer not to have powdered Teflon added to my food. So they spend many paragraphs citing all the scientific studies on the safety of Teflon—it didn’t hurt rats in feeding trials!—as well as the many applications for which it is already being used. These include Teflon-coated stirring rods used in labs and coatings on medical devices like bladder catheters and gynecological implants, as well as the catheters used for in vitro fertilization. And guys, you’ll be happy to know that Teflon doesn’t seem to affect sperm motility or viability. I suspect this will still be a hard sell in the consumer marketplace.

Physics

Cacio e pepe is an iconic pasta dish that is also frustratingly difficult to make — Credit: Simone Frau

Citation: Giacomo Bartolucci, Daniel Maria Busiello, Matteo Ciarchi, Alberto Corticelli, Ivan Di Terlizzi, Fabrizio Olmeda, Davide Revignas, and Vincenzo Maria Schimmenti, for discoveries about the physics of pasta sauce, especially the phase transition that can lead to clumping, which can be a cause of unpleasantness.

“Pasta alla cacio e pepe” is a simple dish: just tonnarelli pasta, pecorino cheese, and pepper. But its simplicity is deceptive. The dish is notoriously challenging to make because it’s so easy for the sauce to form unappetizing clumps with a texture more akin to stringy mozzarella rather than being smooth and creamy. As we reported in April, Italian physicists came to the rescue with a foolproof recipe based on their many scientific experiments, according to a new paper published in the journal Physics of Fluids. The trick: using corn starch for the cheese and pepper sauce instead of relying on however much starch leaches into the boiling water as the pasta is cooked.

Traditionally, the chef will extract part of the water and starch solution—which is cooled to a suitable temperature to avoid clumping as the cheese proteins “denaturate”—and mix it with the cheese to make the sauce, adding the pepper last, right before serving. But the authors note that temperature is not the only factor that can lead to this dreaded “mozzarella phase.” If one tries to mix cheese and water without any starch, the clumping is more pronounced. There is less clumping with water containing a little starch, like water in which pasta has been cooked. And when one mixes the cheese with pasta water “risottata”—i.e., collected and heated in a pan so enough water evaporates that there is a higher concentration of starch—there is almost no clumping.

The authors found that the correct starch ratio is between 2 to 3 percent of the cheese weight. Below that, you get the clumping phase separation; above that, and the sauce becomes stiff and unappetizing as it cools. Pasta water alone contains too little starch. Using pasta water “risottata” may concentrate the starch, but the chef has less control over the precise amount of starch. So the authors recommend simply dissolving 4 grams of powdered potato or corn starch in 40 grams of water, heating it gently until it thickens and combining that gel with the cheese. They also recommend toasting the black pepper briefly before adding it to the mixture to enhance its flavors and aromas.

Engineering Design

Experimental set-up (a) cardboard enclosure (b) UV-C tube light (c) SMPS — Credit: Vikash Kumar and Sarthak Mittal

Citation: Vikash Kumar and Sarthak Mittal, for analyzing, from an engineering design perspective, “how foul-smelling shoes affects the good experience of using a shoe-rack.”

Shoe odor is a universal problem, even in India, according to the authors of this paper, who hail from Shiv Nadar University (SNU) in Uttar Pradesh. All that heat and humidity means people perspire profusely when engaging even in moderate physical activity. Add in a lack of proper ventilation and washing, and shoes become a breeding ground for odor-causing bacteria called Kytococcus sedentarius. Most Indians make use of shoe racks to store their footwear, and the odors can become quite intense in that closed environment.

Yet nobody has really studied the “smelly shoe” problem when it comes to shoe racks. Enter Kumar and Mittal, who conducted a pilot study with the help of 149 first-year SNU students. More than half reported feeling uncomfortable about their own or someone else’s smelly shoes, and 90 percent kept their shoes in a shoe rack. Common methods to combat the odor included washing the shoes and drying them in the sun; using spray deodorant; or sprinkling the shoes with an antibacterial powder. They were unaware of many current odor-combatting products on the market, such as tea tree and coconut oil solutions, thyme oil, or isopropyl alcohol.

Clearly, there is an opportunity to make a killing in the odor-resistant shoe rack market. So naturally Kumar and Mittal decided to design their own version. They opted to use bacteria-killing UV rays (via a UV-C tube light) as their built-in “odor eater,” testing their device on the shoes of several SNU athletes, “which had a very strong noticeable odor.” They concluded that an exposure time of two to three minutes was sufficient to kill the bacteria and get rid of the odor.

Aviation

Wing membranes (patagia) of Townsend's big-eared bat, Corynorhinus townsendii — Credit: Public domain

Citation: Francisco Sánchez, Mariana Melcón, Carmi Korine, and Berry Pinshow, for studying whether ingesting alcohol can impair bats’ ability to fly and also their ability to echolocate.

Nature is rife with naturally occurring ethanol, particularly from ripening fruit, and that fruit in turn is consumed by various microorganisms and animal species. There are occasional rare instances of some mammals, birds, and even insects consuming fruit rich in ethanol and becoming intoxicated, making those creatures more vulnerable to potential predators or more accident-prone due to lessened motor coordination. Sánchez et al. decided to look specifically at the effects of ethanol on Egyptian fruit bats, which have been shown to avoid high-ethanol fruit. The authors wondered if this might be because the bats wanted to avoid becoming inebriated.

They conducted their experiments on adult male fruit bats kept in an outdoor cage that served as a long flight corridor. The bats were given liquid food with varying amounts of ethanol and then released in the corridor, with the authors timing how long it took each bat to fly from one end to the other. A second experiment followed the same basic protocol, but this time the authors recorded the bats’ echolocation calls with an ultrasonic microphone. The results: The bats that received liquid food with the highest ethanol content took longer to fly the length of the corridor, evidence of impaired flight ability. The quality of those bats’ echolocation was also adversely affected, putting them at a higher risk of colliding with obstacles mid-flight.

Psychology

Narcissus (1597–99) by Caravaggio; the man in love with his own reflection — Credit: Public domain

Citation: Marcin Zajenkowski and Gilles Gignac, for investigating what happens when you tell narcissists—or anyone else—that they are intelligent.

Not all narcissists are created equal. There are vulnerable narcissists who tend to be socially withdrawn, have low self-esteem, and are prone to negative emotions. And then there are grandiose narcissists, who exhibit social boldness, high self-esteem, and are more likely to overestimate their own intelligence. The prevailing view is that this overconfidence stems from narcissism. The authors wanted to explore whether this effect might also work in reverse, i.e., that believing one has superior intelligence due to positive external feedback can lead to at least a temporary state of narcissism.

Zajenkowski et al. recruited 361 participants from Poland who were asked to rate their level of intelligence compared to other people; complete the Polish version of the Narcissistic Personality Inventory; and take an IQ test to compare their perceptions of their own intelligence with an objective measurement. The participants were then randomly assigned to one of two groups. One group received positive feedback—telling them they did indeed have a higher IQ than most people—while the other received negative feedback.

The results confirmed most of the researchers’ hypotheses. In general, participants gave lower estimates of their relative intelligence after completing the IQ test, which provided an objective check of sorts. But the type of feedback they received had a measurable impact. Positive feedback enhanced their feelings of uniqueness (a key aspect of grandiose narcissism). Those who received negative feedback rated their own intelligence as being lower, and that negative feedback had a larger effect than positive feedback. The authors concluded that external feedback helped shape the subjects’ perception of their own intelligence, regardless of the accuracy of that feedback.

Nutrition

Rainbow lizards eating ‘four cheese’ pizza at a seaside touristic resort in Togo. — Credit: Daniele Dendi et al, 2022

Citation: Daniele Dendi, Gabriel H. Segniagbeto, Roger Meek, and Luca Luiselli, for studying the extent to which a certain kind of lizard chooses to eat certain kinds of pizza.

Move over, Pizza Rat, here come the Pizza Lizards—rainbow lizards, to be precise. This is a species common to urban and suburban West Africa. The lizards primarily live off insects and arthropods, but their proximity to humans has led to some developing a more omnivorous approach to their foraging. Bread is a particular favorite. Case in point: One fine sunny day at a Togo seaside resort, the authors noticed a rainbow lizard stealing a tourist’s slice of four-cheese pizza and happily chowing down.

Naturally, they wanted to know if this was an isolated incident or whether the local rainbow lizards routinely feasted on pizza slices. And did the lizards have a preferred topping? Inquiring minds need to know. So they monitored the behavior of nine particular lizards, giving them the choice between a plate of four-cheese pizza and a plate of “four seasons” pizza, spaced about 10 meters apart.

It only took 15 minutes for the lizards to find the pizza and eat it, sometimes fighting over the remaining slices. But they only ate the four-cheese pizza. For the authors, this suggests there might be some form of chemical cues that attract them to the cheesy pizzas, or perhaps it’s easier for them to digest. I’d love to see how the lizards react to the widely derided Canadian bacon and pineapple pizza.

Pediatrics

Citation: Julie Mennella and Gary Beauchamp, for studying what a nursing baby experiences when the baby’s mother eats garlic.

Mennella and Beauchamp designed their experiment to investigate two questions: whether the consumption of garlic altered the odor of a mother’s breast milk, and if so, whether those changes affected the behavior of nursing infants. (Garlic was chosen because it is known to produce off flavors in dairy cow milk and affect human body odor.) They recruited eight women who were exclusively breastfeeding their infants, taking samples of their breast milk over a period when the participants abstained from eating sulfurous foods (garlic, onion, asparagus), and more samples after the mothers consumed either a garlic capsule or a placebo.

The results: Mothers who ingested the garlic capsules produced milk with a perceptibly more intense odor, as evaluated by several adult panelists brought in to sniff the breast milk samples. The strong odor peaked at two hours after ingestion and decreased fats, which is consistent with prior research on cows that ingested highly odorous feeds. As for the infants, those whose mothers ingested garlic attached to the breast for longer periods and sucked more when the milk smelled like garlic. This could be relevant to ongoing efforts to determine whether sensory experiences during breastfeeding can influence how readily infants accept new foods upon weaning, and perhaps even their later food preferences.

Literature

closeup of a hand with clubbed fingernails — Credit: William B. Bean

Citation: The late Dr. William B. Bean, for persistently recording and analyzing the rate of growth of one of his fingernails over a period of 35 years.

If you’re surprised to see a study on fingernail growth rates under the Literature category, it will all make sense once you read the flowery prose stylings of Dr. Bean. He really did keep detailed records of how fast his fingernails grew for 35 years, claiming in his final report that “the nail provides a slowly moving keratin kymograph that measures age on the inexorable abscissa of time.” He sprinkles his observations with ponderous references to medieval astrology, James Boswell, and Moby Dick, with a dash of curmudgeonly asides bemoaning the sterile modern medical teaching methods that permeate “the teeming mass of hope and pain, technical virtuosity, and depersonalization called a ‘health center.'”

So what did our pedantic doctor discover in those 35 years, not just studying his own nails, but meticulously reviewing all the available scientific literature? Well, for starters, the rate of fingernail growth diminishes as one ages; Bean noted that his growth rates remained steady early on, but “slowed down a trifle” over the last five years of his project. Nails grow faster in children than adults. A warm environment can also accelerate growth, as does biting one’s fingernails—perhaps, he suggests, because the biting stimulates blood flow to the area. And he debunks the folklore of hair and nails growing even after death: it’s just the retraction and contraction of the skin post-mortem that makes it seem like the nails are growing.

Peace

Citation: Fritz Renner, Inge Kersbergen, Matt Field, and Jessica Werthmann, for showing that drinking alcohol sometimes improves a person’s ability to speak in a foreign language.

Alcohol is well-known to have detrimental effects on what’s known in psychological circles as “executive functioning,” impacting things like working memory and inhibitory control. But there’s a widespread belief among bilingual people that a little bit of alcohol actually improves one’s fluency in a foreign language, which also relies on executive functioning. So wouldn’t being intoxicated actually have an adverse effect on foreign language fluency? Renner et al. decided to investigate further.

They recruited 50 native German-speaking undergrad psychology students at Maastricht University in the Netherlands who were also fluent in Dutch. They were randomly divided into two groups. One group received an alcoholic drink (vodka with bitter lemon), and the other received water. Each participant consumed enough to be slightly intoxicated after 15 minutes, and then engaged in a discussion in Dutch with a native Dutch speaker. Afterward, they were asked to rate their self-perception of their skill at Dutch, with the Dutch speakers offering independent observer ratings.

The researchers were surprised to find that intoxication improved the participants’ Dutch fluency, based on the independent observer reports. (Self-evaluations were largely unaffected by intoxication levels.) One can’t simply attribute this to so-called “Dutch courage,” i.e., increased confidence associated with intoxication. Rather, the authors suggest that intoxication lowers language anxiety, thereby increasing one’s foreign language proficiency, although further research would be needed to support that hypothesis.

Jennifer is a senior writer 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.

Meet the 2025 Ig Nobel Prize winners Read More »

Trump’s Golden Dome will cost 10 to 100 times more than the Manhattan Project

american enterprise institute, Department of Defense, golden dome, military space, missile defense, Science, Space, US Space Force / Shannon Garcia / September 18, 2025

Instead, the $252 billion option would include additional Patriot missile batteries and air-control squadrons, dozens of new aircraft, and next-generation systems to defend against drone and cruise missile attacks on major population centers, military bases, and other key areas.

At the other end of the spectrum, Harrison writes that the “most robust air and missile defense shield possible” will cost some $3.6 trillion through 2045, nearly double the life cycle cost of the F-35 fighter jet, the most expensive weapons program in history.

“In his Oval Office announcement, President Trump set a high bar for Golden Dome, declaring that it would complete ‘the job that President Reagan started 40 years ago, forever ending the missile threat to the American homeland and the success rate is very close to 100 percent,'” Harrison writes.

The numbers necessary to achieve this kind of muscular defense are staggering: 85,400 space-based interceptors, 14,510 new air-launched interceptors, 46,904 more surface-launched interceptors, hundreds of new sensors on land, in the air, at sea, and in space to detect incoming threats, and more than 20,000 additional military personnel.

SpaceX’s Starship rocket could offer a much cheaper ride to orbit for thousands of space-based missile interceptors. Credit: SpaceX

No one has placed missile interceptors in space before, and it will require thousands of them to meet even the most basic goals for Golden Dome. Another option Harrison presents in his paper would emphasize fast-tracking a limited number of space-based interceptors that could defend against a smaller attack of up to five ballistic missiles, plus new missile warning and tracking satellites, ground- and sea-based interceptors, and other augmentations of existing missile-defense forces.

That would cost an estimated $471 billion over the next 20 years.

Supporters of the Golden Dome project say it’s much more feasible today to field space-based interceptors than it was in the Reagan era. Commercial assembly lines are now churning out thousands of satellites per year, and it’s cheaper to launch them today than it was 40 years ago.

A report released by the nonpartisan Congressional Budget Office (CBO) in May examined the effect of reduced launch prices on potential Golden Dome architectures. The CBO estimated that the cost of deploying between 1,000 and 2,000 space-based interceptors would be between 30 and 40 percent cheaper today than the CBO found in a previous study in 2004.

But the costs just for deploying up to 2,000 space-based interceptors remain astounding, ranging from $161 billion to $542 billion over 20 years, even with today’s reduced launch prices, according to the CBO. The overwhelming share of the cost today would be developing and building the interceptors themselves, not launching them.

Trump’s Golden Dome will cost 10 to 100 times more than the Manhattan Project Read More »