Science

rocket-report:-firefly’s-ceo-steps-down;-artemis-ii-core-stage-leaves-factory

Rocket Report: Firefly’s CEO steps down; Artemis II core stage leaves factory

astra, china, Commercial space, Firefly Aerospace, launch, long march, NASA, rocket report, Science, Space, space launch system, spacex, starship / /

Vaya con dios —

Rocket Factory Augsburg completed qualification of its upper stage for a first launch this year.

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The core stage for NASA's second Space Launch System rocket rolls aboard a barge that will take it from New Orleans to Kennedy Space Center in Florida.

Enlarge / The core stage for NASA’s second Space Launch System rocket rolls aboard a barge that will take it from New Orleans to Kennedy Space Center in Florida.

Welcome to Edition 7.03 of the Rocket Report! One week ago, SpaceX suffered a rare failure of its workhorse Falcon 9 rocket. In fact, it was the first time the latest version of the Falcon 9, known as the Block 5, has ever failed on its prime mission after nearly 300 launches. The world’s launch pads have been silent since the grounding of the Falcon 9 fleet after last week’s failure. This isn’t surprising, but it’s noteworthy. After all, the Falcon 9 has flown more this year than all of the world’s other rockets combined and is fundamental to much of what the world does in space.

As always, we welcome reader submissions. If you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.

Astra finally goes private, again. A long-simmering deal for Astra’s founders to take the company private has been finalized, the company announced Thursday, capping the rocket launch company’s descent from blank-check darling to delisting in three years, Bloomberg reports. The launch company’s valuation peaked at $3.9 billion in 2021, the year it went public, and was worth about $12.2 million at the end of March, according to data compiled by Bloomberg. Astra’s chief executive officer, Chris Kemp, and chief technology officer, Adam London, founded the company in 2016 with the goal of essentially commoditizing launch services for small satellites. But Astra’s rockets failed to deliver and fell short of orbit five times in seven tries.

Spiraling … Astra’s stock price tanked after the spate of launch failures, drying up its funding spigot as Kemp tried to pivot toward a slightly larger, more reliable rocket. Astra acquired a company named Apollo Fusion in 2021, entering a new business segment to produce electric thrusters for small satellites. But Astra’s launch business faltered, and last November Kemp and London submitted an offer to retake ownership of the company. Astra announced the closure of the take-private deal Thursday, with Kemp and London acquiring the company’s outstanding shares for 50 cents per share in cash, below the stock’s final listing price of 53 cents. “We will now focus all of our attention on a successful launch of Rocket 4, delivering satellite engines to our customers, and building a company of consequence,” Kemp said. (submitted by EllPeaTea and Ken the Bin)

Firefly chief leaves company. Launch startup Firefly Aerospace parted ways with CEO Bill Weber, Payload reports. The announcement of Weber’s departure late Wednesday came two days after Payload reported Firefly was investigating claims of an alleged inappropriate relationship between him and a female employee. “Firefly Aerospace’s Board of Directors announced that Bill Weber is no longer serving as CEO of the company, effective immediately,” the company said in a statement Wednesday night. Peter Schumacher takes over as interim CEO while Firefly searches for a new permanent chief executive. Schumacher was an interim CEO at Firefly before Weber’s hiring in 2022.

Two days and gone … Payload published the first report of Weber’s alleged improper relationship with a female employee Monday. Two days later, Weber was gone. Payload reported an executive brought his concerns about the alleged relationship to Firefly’s board and resigned because he lost confidence in leadership at the company. Citing four current and former employees, Payload reported Firefly’s culture became “chaotic” since Weber took the helm in 2022 after its acquisition by AE Industrial Partners. The Texas-based company achieved some success during Weber’s tenure, with four orbital launches of its Alpha rocket, although two of the flights ended up in lower-than-planned orbits. (submitted by Ken the Bin)

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Themis hop tests delayed to next year. The initial hop tests of the European Themis reusable booster, developed by ArianeGroup and funded by ESA, won’t start until next year, European Spaceflight reports. The Swedish Space Corporation, which operates the space center in Sweden where Themis will initially fly, confirmed the schedule change. Once ArianeGroup moves on to higher altitude flights, the testing will be moved to the Guiana Space Center. ESA awarded the first development contract for the Themis booster in 2019, and the first hop tests were then scheduled for 2022. Themis’ hops will be similar to SpaceX’s Grasshopper rocket, which performed a series of up-and-down atmospheric test flights before SpaceX started recovering and reusing Falcon 9 boosters.

Fate of Themis … The Themis booster is powered by the methane-fueled Prometheus engine, also funded by ESA. A large European reusable rocket is unlikely to fly until the 2030s, but a subsidiary of ArianeGroup named MaiaSpace is developing a smaller partially reusable two-stage rocket slated to debut as soon as next year. The Maia rocket will use a modified Themis booster as its first stage. “As a result, for MaiaSpace, the continued and rapid development of the Themis program is essential to ensure it can hit its projected target of an inaugural flight of Maia in 2025,” European Spaceflight reports. (submitted by Ken the Bin)

Rocket Report: Firefly’s CEO steps down; Artemis II core stage leaves factory Read More »

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Long COVID rates have declined, especially among the vaccinated, study finds

covid-10 vaccines, COVID-19, Delta, health, long COVID, omicron, SARS-CoV-2, Science, vaccinated, variants / /

Good news —

In large study, rates of long COVID fell from 10% to 3.5% for the vaccinated.

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Long covid activists attend the Senate Appropriations Subcommittee on Labor, Health and Human Services, Education, and Related Agencies hearing on the

Enlarge / Long covid activists attend the Senate Appropriations Subcommittee on Labor, Health and Human Services, Education, and Related Agencies hearing on the “Fiscal Year 2025 Budget Request for the National Institutes of Health,” in Dirksen building on May 23, 2024.

As a summer wave of COVID-19 infections swells once again, a study published this week in the New England Journal of Medicine offers some positive news about the pandemic disease: Rates of long COVID have declined since the beginning of the health crisis, with rates falling from a high of 10.4 percent before vaccines were available to a low of 3.5 percent for those vaccinated during the omicron era, according to the new analysis.

The study, led by Ziyad Al-Aly, chief of research at the VA Saint Louis Health Care System, used data from a wealth of health records in the Department of Veterans Affairs. The researchers ultimately included data from over 440,000 veterans who contracted COVID-19 sometime between March 1, 2020, and January 31, 2022, as well as over 4.7 million uninfected veterans who acted as controls.

Al-Aly and colleagues divided the population into eight groups. People who were infected during the study period were divided into five groupings by the dates of their first infection and their vaccination status. The first group included those infected in the pre-delta era before vaccines were available (March 1, 2020, to June 18, 2021). Then there were vaccinated and unvaccinated groups who were infected in the delta era (June 19, 2021, to December 18, 2021) and the omicron era (December 19, 2021, and January 31, 2022). The uninfected controls made up the final three of eight groups, with the controls assigned to one of the three eras.

On the decline

In the pre-delta/pre-vaccine era, 10.42 out of 100 unvaccinated people infected developed long COVID in the year after their infection, which the researchers referred to as PASC, or postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In the delta era, the rate of long COVID among the unvaccinated fell slightly to 9.51 out of 100. But for the vaccinated, the rate fell much further, to 5.35 out of 100. A similar pattern was seen in the omicron era. For the unvaccinated, the rate of long COVID again fell slightly to 7.76 per 100 people, while the vaccinated saw their rate fall to 3.5 per 100.

In a secondary statistical analysis, called a decomposition analysis, the researchers found that vaccines could explain about 72 percent of the cumulative decline in long COVID rates across the eras, while era-related factors explained about 28 percent. Those era-related factors could include differences in the virus, improved treatments, and use of anti-viral medications.

Further, looking at data on the disease categories related to long COVID cases, the researchers also did an analysis finding a shift in symptoms over the eras. The researchers looked at over 10 disease categories: cardiovascular, coagulation and hematologic, fatigue, gastrointestinal, kidney, mental health, metabolic, musculoskeletal, neurologic, and pulmonary. Compared to the two earlier eras, the researchers noted an increase in gastrointestinal, metabolic, and musculoskeletal diseases involved in long COVID cases in the omicron era.

Overall, the study points to a welcomed decline in the rates of long COVID among the infected, particularly for those who are vaccinated. But, it also makes clear that long COVID isn’t a thing of the past: “a substantial residual risk of PASC remains among vaccinated persons who had SARS-CoV-2 infection during the omicron era,” Al-Aly and his colleagues conclude.

The study also has some limitations, leaving lingering questions for further study. One is whether the type or number of vaccines affect the risk of long COVID—that was not included in the study. The study also didn’t allow researchers to assess whether repeat infections increase the burden of long COVID.

Long COVID rates have declined, especially among the vaccinated, study finds Read More »

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Illegal drug found in Diamond Shruumz candies linked to severe illnesses

diamond shruumz, hallucinogenic, health, muscimol, Mushroom, poison, psilocin, psilocybin, psychedelics, Science / /

More drugs —

New testing finds psilocin, related to psilocybin, in gummies purchased in 2023.

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Illegal drug found in Diamond Shruumz candies linked to severe illnesses

Newly released testing data of Diamond Shruumz-brand gummies purchased in 2023 identified the presence of psilocin, a hallucinogenic drug closely related to the magic-mushroom drug psilocybin that is classified as a Schedule I drug, alongside psilocybin, heroin, and LSD.

The finding comes as Diamond Shruumz’s current line of gummies, chocolates, and candy cones is being recalled and are under active investigation in connection to a nationwide rash of severe illnesses, which have involved seizures, intubation, and intensive care. As of the latest update on July 15, 69 people in 28 states have been sickened after eating a Diamond Shruumz product. Sixty of the 69 sought medical care, 36 were hospitalized, and there is one potentially associated death under investigation.

The new finding of psilocin in the products, published by researchers at the University of Virginia, adds to growing concern about psychedelic mushroom candies generally. Although the candies are marketed as being legal, they have often been found to contain various undisclosed illegal drugs, gray market synthetic versions of drugs, as well as dangerous adulterants and contaminants.

In the ongoing investigation of Diamond Shruumz candies—led by the Food and Drug Administration and the Centers for Disease Control and Prevention, with the help of America’s Poison Centers and state and local partners—researchers have not identified psilocin in products linked to the illnesses. Instead, they have found a closely related synthetic hallucinogenic compound called 4-acetoxy-N,N-dimethyltryptamine, also known as psilacetin or 4-AcO-DMT. Psilacetin is thought to be metabolized into psilocin in the body and is said to have similar effects as taking magic mushrooms or psilocybin. The different testing results between the FDA-led investigation and the new UVA study may be due to possible formulation changes between 2023 and 2024 or simply differences in the products or batches of candies tested so far.

The UVA researchers, who published their findings in the CDC’s Morbidity and Mortality Weekly Report, looked into the mushroom candies after four adults reported illnesses to a local poison control center between September and November 2023. The people went to the emergency department with tachycardia, confusion, anxiety or somnolence, and nausea after eating gummy candies labeled as containing Amanita muscaria mushrooms. Amid their investigation into those cases, a 3-year-old also fell ill in June 2024 after accidentally eating two gummies sold as containing A. muscaria. All of the adults and the toddler recovered from their illnesses quickly, though the toddler was hospitalized for a day for observation.

Not legal or safe

A. muscaria is a legal hallucinogenic mushroom that contains psychoactive compounds ibotenic acid and muscimol. These resemble neurotransmitters in the brain and can cause gastrointestinal symptoms, agitation, and seizures.

The UVA researchers couldn’t track down the specific brands or products the sickened adults took, but they collected six similar products from nearby gas stations and smoke shops. Those six products included two Diamond Shruumz products, which were not sold as containing A. muscaria. Using liquid chromatography-mass spectrometry, the researchers found that the two Diamond Shruumz gummy products (Sour Peach Apple and Rainbow flavors) contained psilocin. The Rainbow flavor also contained caffeine.

In addition, a product labeled as “Wonderland Legal Psychedelics Cherry Nirvana” contained psilocin, the synthetic hallucinogen N,N-dimethyltryptamine, a compound found in kratom called mitragynine, and caffeine.  A product labeled as “Urb Magic Amanita Mushroom Watermelon” contained psilocybin, psilocin, and the stimulant 2-phenethylamine. A product called “Psilly’s Legal Psychedelic Mushrooms Fruit Punch” contained the stimulant ephedrine, and the product “Tryp mushroom gummies” wasn’t found to contain any concerning compounds.

The UVA study was not able to test for ibotenic acid or muscimol. In Diamond Shruumz’s recall notice, the company said it had found higher than normal levels of muscimol in its products. FDA testing has not identified muscimol in product testing, according to results released so far.

“People tend to equate ‘legal’ with ‘safe,’ which is not necessarily the case. These products are not regulated and can contain any number of unlabeled substances which, when consumed, can cause undesired symptoms,” lead author of the UVA study Avery Michienzi said in a statement. “Some packages will have QR codes showing that the products were tested in a lab and contain only what they are labeled to contain. These have been found to be inaccurate.”

The FDA this week warned that even though all of Diamond Shruumz’s products have been recalled, they remain on the shelves of stores nationwide. The agency said it is reaching out to industry partners to raise awareness of the recall and monitoring the effectiveness of Diamond Shruumz’s recall efforts.

Illegal drug found in Diamond Shruumz candies linked to severe illnesses Read More »

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Coal-filled trains are likely sending people to the hospital

Science / /

Training for black lung —

Coal-filled trains trail a cloud of particulates shaken free from their cargo.

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a long line of open-top rail cars filled with coal against a parched, scrub filled hill.

Although US coal consumption has fallen dramatically since 2005, the country still consumes millions of tons a year, and exports tons more—much of it transported by train. Now, new research shows that these trains can affect the health of people living near where they pass.

The study found that residents living near railroad tracks likely have higher premature mortality rates due to air pollutants released during the passage of uncovered coal trains. The analysis of the San Francisco Bay Area cities of Oakland, Richmond, and Berkeley shows that increases in air pollutants such as small particulate matter (PM 2.5) are also associated with increases in asthma-related episodes and hospital admissions.

“This has never been studied in the world. There’s been a couple studies trying to measure just the air pollution, usually in rural areas, but this was the first to both measure air pollution and trains in an urban setting,” said Bart Ostro, author of the study and an epidemiologist at the University of California, Davis.

Persistent coal pollution

Trains carry nearly 70 percent of coal shipments in the United States, leaving a trail of pollution in their wake. And coal exports will have a similar impact during transit. Ostro explained that when uncovered coal trains travel, the coal particles disperse around the railroad tracks. Levels of PM 2.5 “[spread] almost a mile away,” he added.

As a result, the mere passage of coal trains could affect the health of surrounding communities. Ostro was particularly concerned about how these pollutants could harm vulnerable populations living near the coal export terminal in Richmond. Previous census data had already shown that those in Richmond who live around the rail line have mortality rates 10 to 50 percent higher than the county average. Communities in Oakland could be at risk, too, since discussions are underway to build a new coal export terminal in the region.

But before researchers could study the health effects of these air pollutants, they first had to understand how much was spread by passing trains. This was a challenge in itself because coal trains aren’t scheduled like regular passenger trains.

To ensure that researchers could measure all trains and pollutants, Ostro and his team developed a monitoring system with three main components: a weather station to provide meteorological parameters, an air quality sensor to track air pollution levels, and an AI-trained camera to recognize coal trains. The trained cameras were critical to the entire project, identifying different types of trains: full coal trains, empty coal trains, freight trains, and passenger trains.

With the system in place, Ostro’s team measured pollution levels and was able to attribute them directly to coal trains. Their results, published last year, showed that coal trains and terminal operations added a significant amount of PM 2.5 pollution to urban areas, more than other freight or passenger trains. Passing coal trains added an average of eight μg/m3 to ambient pollution. This is two to three micrograms more than freight trains contribute. Even empty coal cars contribute to increased pollution levels due to traces of coal dust.

Particulate problems

This year, in a follow-up study, researchers combined these findings with US Census data and health studies to understand how this increase might affect local communities. They estimated that more than 260,000 people would be exposed to some increase in annual PM 2.5, and that such exposure was associated with significant mortality and morbidity.

Health effects were quantified for three different scenarios based on different wind conditions. In the worst-case scenario, where there’s an increase of about two μg/m3 near the railway line, modeling suggests that premature mortality would increase by 1.3 percent. Hospital admissions for conditions such as chronic lung disease, pneumonia, and cardiovascular disease would also increase by 4.7 percent, 6.2 percent, and 2.2 percent, respectively. Although these are relatively small numbers in a small population, Ostro points out that they could be extrapolated to larger populations in other countries.

“The way I see it, this is a microcosm of what could be happening globally,” he added. While coal use—and the transportation of that coal—is declining in the US and the European Union, the same isn’t happening everywhere. In countries like China and India, for example, coal use is increasing, and populations living near the railroads that transport that coal could be at risk.

“These findings have major implications beyond San Francisco and the US,” said Michel Abramson from Monash University in Australia, who wasn’t involved in the study. The researcher thinks Ostro’s assessment “fills an important gap” by looking at the health effects of transporting coal in uncovered rail cars but doesn’t think there are any solutions to mitigate the problem other than stopping the use of coal.

“Covering the coal cars might not solve the problem, because it could increase the risk of fires,” he added. “Ultimately the world needs to phase out the mining, transport, and combustion of coal, not only to reduce the risks of climate change, but also to improve the health of the population.”

Environmental Research, 2024.  DOI: 10.1016/j.envres.2024.118787

Bárbara Pinho is a science journalist specializing in climate, health, and agriculture, based in Porto, Portugal. Learn more about her work at barbarapinho.com or follow her on X (formerly Twitter) @BarbPinho

Coal-filled trains are likely sending people to the hospital Read More »

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NASA built a Moon rover but can’t afford to get it to the launch pad

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NASA completed assembling the VIPER rover last month at the Johnson Space Center in Houston.

Enlarge / NASA completed assembling the VIPER rover last month at the Johnson Space Center in Houston.

NASA has spent $450 million designing and building a first-of-its-kind robot to drive into eternally dark craters at the Moon’s south pole, but the agency announced Wednesday it will cancel the rover due to delays and cost overruns.

“NASA intends to discontinue the VIPER mission,” said Nicky Fox, head of the agency’s science mission directorate. “Decisions like this are never easy, and we haven’t made this one, in any way, lightly. In this case, the projected remaining expenses for VIPER would have resulted in either having to cancel or disrupt many other missions in our Commercial Lunar Payload Services (CLPS) line.”

NASA has terminated science missions after development delays and cost overruns before, but it’s rare to cancel a mission with a spacecraft that is already built.

The Volatiles Investigating Polar Exploration Rover (VIPER) mission was supposed to be a robotic scout for NASA’s Artemis program, which aims to return astronauts to the lunar surface in the next few years. VIPER was originally planned to launch in late 2023 and was slated to fly to the Moon aboard a commercial lander provided by Pittsburgh-based Astrobotic, which won a contract from NASA in 2020 to deliver the VIPER rover to the lunar surface. Astrobotic is one of 14 companies in the pool of contractors for NASA’s CLPS program, with the goal of transporting government-sponsored science payloads to the Moon.

But VIPER has been delayed at least two years—the most recent schedule projected a launch in September 2025—causing its cost to grow from $433 million to more than $609 million. The ballooning costs automatically triggered a NASA review to determine whether to proceed with the mission or cancel it. Ultimately, officials said they determined NASA couldn’t pay the extra costs for VIPER without affecting other Moon missions.

“Therefore, we’ve made the decision to forego this particular mission, the VIPER mission, in order to be able to sustain the entire program,” Fox said.

“We’re disappointed,” said John Thornton, CEO of Astrobotic. “It’s certainly difficult news… VIPER has been a great team to work with, and we’re disappointed we won’t get the chance to fly them to the Moon.”

NASA said it will consider “expressions of interest” submitted by US industry and international partners by August 1 for use of the existing VIPER rover at no cost to the government. If NASA can’t find anyone to take over VIPER who can pay to get it to the Moon, the agency plans to disassemble the rover and harvest instruments and components for future lunar missions.

Scientists were dismayed by VIPER’s cancellation.

“It’s absurd, to be honest with you,” said Clive Neal, a planetary geologist at the University of Notre Dame. “It made no sense to me in terms of the economics. You’re canceling a mission that is complete, built, ready to go. It’s in the middle of testing.”

“This is a bad mistake,” wrote Phil Metzger, a planetary physicist at the University of Central Florida, in a post on X. “This was the premier mission to measure lateral and vertical variations of lunar ice in the soil. It would have been revolutionary. Other missions don’t replace what is lost here.”

Built with nowhere to go

Engineers at NASA’s Johnson Space Center in Houston finished assembling the VIPER rover last month, and managers gave approval to put the craft through environmental testing to make sure VIPER could withstand the acoustics and vibrations of launch and the extreme temperature swings it would encounter in space.

Instead, NASA has canceled the mission after spending $450 million to get it to this point. “This is a very tough decision, but it is a decision based on budgetary concerns in a very constrained budget environment,” Fox told reporters Wednesday.

VIPER is about the size of a golf cart, with four wheels, headlights, a drill, and three science instruments to search for water ice in depressions near the Moon’s south pole that have been shaded from sunlight for billions of years. This has allowed these so-called permanently shadowed regions to become cold traps, allowing water ice to accumulate at or near the surface, where it could be accessible for future astronauts to use as drinking water or an oxygen source or to convert into electricity and rocket fuel.

But first, scientists need to know exactly where the water is located and how easy it is to reach. VIPER was supposed to be the next step in mapping resources on the Moon, providing ground truth measurements to corroborate remote sensing data from satellites in lunar orbit.

But late parts deliveries delayed construction of the VIPER rover, and in 2022, NASA ordered additional testing of Astrobotic’s Griffin lunar lander to improve the chances of a successful landing with VIPER. This delayed VIPER’s launch from late 2023 until late 2024, and at the beginning of this year, more supply chain issues with the VIPER rover and the Griffin lander pushed back the launch until September 2025.

This most recent delay raised the projected cost of VIPER more than 30 percent over the original cost of the mission, prompting a NASA termination review. While the rover is now fully assembled, NASA still needed to put it through a lengthy series of tests, complete development of the ground systems to control VIPER on the Moon, and deliver the craft to Astrobotic for integration onto the Griffin lander.

The remaining work to complete VIPER and operate it for 100 days on the lunar surface would have cost around $84 million, according to Kearns.

NASA built a Moon rover but can’t afford to get it to the launch pad Read More »

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Researchers track individual neurons as they respond to words

Biology, brains, language, neural implants, neurobiology, Science / /

Pondering phrasing —

When processing language, individual neurons respond to words with similar meanings.

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Human Neuron, Digital Light Microscope. (Photo By BSIP/Universal Images Group via Getty Images)

Enlarge / Human Neuron, Digital Light Microscope. (Photo By BSIP/Universal Images Group via Getty Images)

BSIP/Universal Images Group via Getty Images

“Language is a huge field, and we are novices in this. We know a lot about how different areas of the brain are involved in linguistic tasks, but the details are not very clear,” says Mohsen Jamali, a computational neuroscience researcher at Harvard Medical School who led a recent study into the mechanism of human language comprehension.

“What was unique in our work was that we were looking at single neurons. There is a lot of studies like that on animals—studies in electrophysiology, but they are very limited in humans. We had a unique opportunity to access neurons in humans,” Jamali adds.

Probing the brain

Jamali’s experiment involved playing recorded sets of words to patients who, for clinical reasons, had implants that monitored the activity of neurons located in their left prefrontal cortex—the area that’s largely responsible for processing language. “We had data from two types of electrodes: the old-fashioned tungsten microarrays that can pick the activity of a few neurons; and the Neuropixel probes which are the latest development in electrophysiology,” Jamali says. The Neuropixels were first inserted in human patients in 2022 and could record the activity of over a hundred neurons.

“So we were in the operation room and asked the patient to participate. We had a mixture of sentences and words, including gibberish sounds that weren’t actual words but sounded like words. We also had a short story about Elvis,” Jamali explains. He said the goal was to figure out if there was some structure to the neuronal response to language. Gibberish words were used as a control to see if the neurons responded to them in a different way.

“The electrodes we used in the study registered voltage—it was a continuous signal at 30 kHz sampling rate—and the critical part was to dissociate how many neurons we had in each recording channel. We used statistical analysis to separate individual neurons in the signal,” Jamali says. Then, his team synchronized the neuronal activity signals with the recordings played to the patients down to a millisecond and started analyzing the data they gathered.

Putting words in drawers

“First, we translated words in our sets to vectors,” Jamali says. Specifically, his team used the Word2Vec, a technique used in computer science to find relationships between words contained in a large corpus of text. What Word2Vec can do is tell if certain words have something in common—if they are synonyms, for example. “Each word was represented by a vector in a 300-dimensional space. Then we just looked at the distance between those vectors and if the distance was close, we concluded the words belonged in the same category,” Jamali explains.

Then the team used these vectors to identify words that clustered together, which suggested they had something in common (something they later confirmed by examining which words were in a cluster together). They then determined whether specific neurons responded differently to different clusters of words. It turned out they did.

“We ended up with nine clusters. We looked at which words were in those clusters and labeled them,” Jamali says. It turned out that each cluster corresponded to a neat semantic domain. Specialized neurons responded to words referring to animals, while other groups responded to words referring to feelings, activities, names, weather, and so on. “Most of the neurons we registered had one preferred domain. Some had more, like two or three,” Jamali explained.

The mechanics of comprehension

The team also tested if the neurons were triggered by the mere sound of a word or by its meaning. “Apart from the gibberish words, another control we used in the study was homophones,” Jamali says. The idea was to test if the neurons responded differently to the word “sun” and the word “son,” for example.

It turned out that the response changed based on context. When the sentence made it clear the word referred to a star, the sound triggered neurons triggered by weather phenomena. When it was clear that the same sound referred to a person, it triggered neurons responsible for relatives. “We also presented the same words at random without any context and found that it didn’t elicit as strong a response as when the context was available,” Jamali claims.

But the language processing in our brains will need to involve more than just different semantic categories being processed by different groups of neurons.

“There are many unanswered questions in linguistic processing. One of them is how much a structure matters, the syntax. Is it represented by a distributed network, or can we find a subset of neurons that encode structure rather than meaning?” Jamali asked. Another thing his team wants to study is what the neural processing looks like during speech production, in addition to comprehension. “How are those two processes related in terms of brain areas and the way the information is processed,” Jamali adds.

The last thing—and according to Jamali the most challenging thing—is using the Neuropixel probes to see how information is processed across different layers of the brain. “The Neuropixel probe travels through the depths of the cortex, and we can look at the neurons along the electrode and say like, ‘OK, the information from this layer, which is responsible for semantics, goes to this layer, which is responsible for something else.’ We want to learn how much information is processed by each layer. This should be challenging, but it would be interesting to see how different areas of the brain are involved at the same time when presented with linguistic stimuli,” Jamali concludes.

Nature, 2024.  DOI: 10.1038/s41586-024-07643-2

Researchers track individual neurons as they respond to words Read More »

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Researchers build ultralight drone that flies with onboard solar

drone, materials science, Physics, robotics, Science, solar power / /

Where does it go? It goes up! —

Bizarre design uses a solar-powered motor that’s optimized for weight.

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Image of a metallic object composed from top to bottom of a propeller, a large cylinder with metallic panels, a stalk, and a flat slab with solar panels and electronics.

Enlarge / The CoulombFly doing its thing.

On Wednesday, researchers reported that they had developed a drone they’re calling the CoulombFly, which is capable of self-powered hovering for as long as the Sun is shining. The drone, which is shaped like no aerial vehicle you’ve ever seen before, combines solar cells, a voltage converter, and an electrostatic motor to drive a helicopter-like propeller—with all components having been optimized for a balance of efficiency and light weight.

Before people get excited about buying one, the list of caveats is extensive. There’s no onboard control hardware, and the drone isn’t capable of directed flight anyway, meaning it would drift on the breeze if ever set loose outdoors. Lots of the components appear quite fragile, as well. However, the design can be miniaturized, and the researchers built a version that weighs only 9 milligrams.

Built around a motor

One key to this development was the researchers’ recognition that most drones use electromagnetic motors, which involve lots of metal coils that add significant weight to any system. So, the team behind the work decided to focus on developing a lightweight electrostatic motor. These rely on charge attraction and repulsion to power the motor, as opposed to magnetic interactions.

The motor the researchers developed is quite large relative to the size of the drone. It consists of an inner ring of stationary charged plates called the stator. These plates are composed of a thin carbon-fiber plate covered in aluminum foil. When in operation, neighboring plates have opposite charges. A ring of 64 rotating plates surrounds that.

The motor starts operating when the plates in the outer ring are charged. Since one of the nearby plates on the stator will be guaranteed to have the opposite charge, the pull will start the rotating ring turning. When the plates of the stator and rotor reach their closest approach, thin wires will make contact, allowing charges to transfer between them. This ensures that the stator and rotor plates now have the same charge, converting the attraction to a repulsion. This keeps the rotor moving, and guarantees that the rotor’s plate now has the opposite charge from the next stator plate down the line.

These systems typically require very little in the way of amperage to operate. But they do require a large voltage difference between the plates (something we’ll come back to).

When hooked up to a 10-centimeter, eight-bladed propeller, the system could produce a maximum lift of 5.8 grams. This gave the researchers clear weight targets when designing the remaining components.

Ready to hover

The solar power cells were made of a thin film of gallium arsenide, which is far more expensive than other photovoltaic materials, but offers a higher efficiency (30 percent conversion compared to numbers that are typically in the mid-20s). This tends to provide the opposite of what the system needs: reasonable current at a relatively low voltage. So, the system also needed a high-voltage power converter.

Here, the researchers sacrificed efficiency for low weight, arranging a bunch of voltage converters in series to create a system that weighs just 1.13 grams, but steps the voltage up from 4.5 V all the way to 9.0 kV. But it does so with a power conversion efficiency of just 24 percent.

The resulting CoulombFly is dominated by the large cylindrical motor, which is topped by the propeller. Suspended below that is a platform with the solar cells on one side, balanced out by the long, thin power converter on the other.

Meet the CoulombFly.

To test their system, the researchers simply opened a window on a sunny day in Beijing. Starting at noon, the drone took off and hovered for over an hour, and all indications are that it would have continued to do so for as long as the sunlight provided enough power.

The total system required just over half a watt of power to stay aloft. Given a total mass of 4 grams, that works out to a lift-to-power efficiency of 7.6 grams per watt. But a lot of that power is lost during the voltage conversion. If you focus on the motor alone, it only requires 0.14 watts, giving it a lift-to-power efficiency of over 30 grams per watt.

The researchers provide a long list of things they could do to optimize the design, including increasing the motor’s torque and propeller’s lift, placing the solar cells on structural components, and boosting the efficiency of the voltage converter. But one thing they don’t have to optimize is the vehicle’s size since they already built a miniaturized version that’s only 8 millimeters high and weighs just 9 milligrams but is able to generate a milliwatt of power that turns its propeller at over 15,000 rpm.

Again, all this is done without any onboard control circuitry or the hardware needed to move the machine anywhere—they’re basically flying these in cages to keep them from wandering off on the breeze. But there seems to be enough leeway in the weight that some additional hardware should be possible, especially if they manage some of the potential optimizations they mentioned.

Nature, 2024. DOI: 10.1038/s41586-024-07609-4  (About DOIs).

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Electric eels inspire novel “jelly” batteries for soft robotics, wearables

batteries, biomimicry, electric eels, Science / /

Soft and stretchy —

Another team built a lithium-ion battery with electrolyte layer that expands by 5,000%.

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closeup of colorful strand held between fingers being stretched

Enlarge / Researchers have developed soft, stretchable “jelly batteries” that could be used for wearable devices or soft robotics.

University of Cambridge

Inspired by the electric shock capabilities of electric eels, scientists have developed a soft, stretchable “jelly” battery ideal for wearable devices or soft robotics, according to a new paper published in the journal Science Advances. With further testing in living organisms, the batteries might even be useful as brain implants for targeted drug delivery to treat epilepsy, among other conditions.

As previously reported, the electric eel produces its signature electric discharges—both low and high voltages, depending on the purpose for discharging—via three pairs of abdominal organs composed of modified muscle cells called electrocytes, located symmetrically along both sides of the eel. The brain sends a signal to the electrocytes, opening ion channels and briefly reversing the polarity. The difference in electric potential then generates a current, much like a battery with stacked plates.

Vanderbilt University biologist and neuroscientist Kenneth Catania is one of the most prominent scientists studying electric eels these days. He has found that the creatures can vary the degree of voltage in their electrical discharges, using lower voltages for hunting purposes and higher voltages to stun and kill prey. Those higher voltages are also useful for tracking potential prey, akin to how bats use echolocation. One species, Volta’s electric eel (Electrophorus voltai), can produce a discharge of up to 860 volts. In theory, if 10 such eels discharged at the same time, they could produce up to 8,600 volts of electricity—sufficient to power 100 light bulbs.

Mimicking Mother Nature

For soft robotics or wearable electronics applications, soft and stretchy devices with tissue-like electronic properties are required. However, “It’s difficult to design a material that is both highly stretchable and highly conductive since those two properties are normally at odds with one another,” said co-author Stephen O’Neill of the University of Cambridge. “Typically, conductivity decreases when a material is stretched.” So he and his colleagues decided to model their jelly battery design on the layered structure of the electric eel’s electrocytes. Whereas conventional electronics employ rigid materials with electrons to carry the charges, this battery would use ions as charge carriers, like the electric eels.

The self-healing jelly batteries can stretch to over 10 times their original length without affecting their conductivity.

Enlarge / The self-healing jelly batteries can stretch to over 10 times their original length without affecting their conductivity.

University of Cambridge

Hydrogels—3D polymer networks composed of 60 percent water—were the obvious choice since they confer the ability to precisely control mechanical properties and can mimic human skin. They are usually made of neutrally charged polymers, but O’Neill et al. added a charge to their polymers, altering the salt component to make them sticky enough to squish together into multiple layers. This builds up a larger energy potential.

The stickiness of the hydrogels comes from the reversible bonds that form between the different layers, thanks to barrel-shaped molecules that act a bit like “molecular handcuffs,” per the authors. So, the jelly batteries can stretch without separating the layers and without any loss of conductivity. Furthermore, “We can customize the mechanical properties of the hydrogels so they match human tissue,” said co-author Oren Scherman. “Since they contain no rigid components such as metal, a hydrogel implant would be much less likely to be rejected by the body or cause the build-up of scar tissue.” That makes them promising for future biomedical applications.

Another stretchy battery

This lithium-ion battery has entirely stretchable components and stable charging and discharging capacity over time.

Enlarge / This lithium-ion battery has entirely stretchable components and stable charging and discharging capacity over time.

Shi Wang et al., ACS Energy Letters, 2024

In related research, a new paper published in the journal ACS Energy Letters described the fabrication of a lithium-ion battery with stretchable components, including an electrolyte layer that can expand by 5,000 percent. The battery can retain its charge storage capacity after nearly 70 charge/discharge cycles. Rather than using a liquid electrolyte, a team of Chinese scientists incorporated the electrolyte into a polymer layer fused between two flexible electrode films.

The electrodes consisted of a thin film of conductive paste embedded with silver nanowires, carbon black, and lithium-based cathode or anode materials onto a plate. They applied a layer of flexible polydimethylsiloxane (used in contact lenses) on top of the paste, followed by a lithium salt, highly conductive liquid, and stretchy polymer ingredients. When zapped with light, all those components formed a solid rubber-like stretchy layer that could still transport lithium ions. This was topped with another electrode film, and the entire device was then sealed in a protective coating. This battery had a roughly six times higher average charge capacity at a fast-charging rate than a similar device with a traditional liquid electrolyte.

Science Advances, 2024. DOI: 10.1126/sciadv.adn5142  (About DOIs).

ACS Energy Letters, 2024. DOI: 10.1021/acsenergylett.4c01254  (About DOIs).

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Five people infected as bird flu appears to go from cows to chickens to humans

avian influenza, bird flu, CDC, Chickens, Colorado, cows, dairy, H5N1, health, infectious diseases, influenza, milk, outbreak, poultry, Science, USDA / /

Cows and chickens and humans, oh my! —

High temperatures made it hard for workers to use protective gear during culling.

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Five people infected as bird flu appears to go from cows to chickens to humans

The highly pathogenic avian influenza H5N1 virus that spilled from wild birds into US dairy cows late last year may have recently seeped from a dairy farm in Colorado to a nearby poultry farm, where it then infected five workers tasked with culling the infected chickens

In a press briefing Tuesday, federal officials reported that four of the avian influenza cases have been confirmed by the Centers for Disease Control and Prevention, while the fifth remains a presumptive positive awaiting CDC confirmation.

All five people have shown mild illnesses, though they experienced variable symptoms. Some of the cases involved conjunctivitis, as was seen in other human cases linked to the H5N1 outbreak in dairy cows. Others in the cluster of five had respiratory and typical flu-like symptoms, including fever, chills, sore throat, runny nose, and cough. None of the five cases required hospitalization.

The virus infecting the five people is closely related to the virus infecting the chickens on the poultry farm, which, in turn, is closely related to virus seen in infected dairy herds and in other human cases that have been linked to the dairy outbreak. The affected poultry farm is in Colorado’s northern county of Weld, which has also reported about two dozen outbreaks of avian influenza in dairy herds.

Dairy to poultry hypothesis

In one fell swoop, Colorado’s poultry farm outbreak has more than doubled the number of human avian influenza cases linked to the dairy cow spillover, bringing the previous tally of four cases to nine. While officials have previously noted instances where it appeared that H5N1 on dairy farms had moved to nearby poultry farms, this appears to be the first time such spread has led to documented human infections.

The link between the poultry farm cases and neighboring dairy farms is still just a hypothesis, however, Nirav Shah, the principal deputy director at the CDC, emphasized to reporters Tuesday. “It is a hypothesis that needs and requires a full investigation. But that is a hypothesis at this point,” he said of the link between the dairy farms and the poultry farm. So far, there is no direct evidence of a specific source of the poultry farm’s infection, and the route of infection is also unclear.

Throughout the outbreak of H5N1 on dairy farms, officials have noted that the primary way the virus appears to spread to new farms is via the movement of cows, people, and machinery between those facilities. There remains no evidence of human-to-human transmission. But milk from infected cows has been found to be brimming with high levels of infectious virus, and milk-contaminated equipment is a prime suspect in the spread.

In the press briefing Tuesday, Eric Deeble, acting senior advisor for H5N1 response with the US Department of Agriculture, noted the poultry are very susceptible to avian influenza and are easily infected. “It does not take much to introduce this into a flock,” Deeble said. The USDA is now working on a “trace-back” investigation on how the Colorado poultry farm was infected.

Searing spread

As for how the farm workers specifically became infected with the virus, health officials pointed to high temperatures that prevented workers from donning protective gear. The poultry farm is a commercial egg layer operation with around 1.8 million birds. Given the presence of bird flu on the premises, all 1.8 million birds need to be culled, aka “depopulated.” This is being carried out using mobile carts with carbon dioxide gas chambers, a common culling method. Workers are tasked with placing the birds in the chambers, which only hold a few dozen birds at a time. In all, the method requires workers to have a high degree of contact with the infected birds, going from bird to bird and batch to batch with the carts.

Amid this grim task, temperatures in the area reached over 100° Fahrenheit, and massive industrial fans were turned on in the facility to try to cool things down. Between the heat and the fans, the approximately 160 people involved in the culling struggled to use personal protective equipment (PPE). The required PPE for the depopulation involves a full Tyvek suit, boots, gloves, goggles, and an N95 respirator.

“The difficulty with wearing all that gear in that kind of heat, you can imagine,” said Julie Gauthier, executive director for field operations at the USDA’s Animal and Plant Health Inspection Service (APHIS). The industrial fans blowing large amounts of air made it yet more difficult for workers to keep goggles and respirators on their faces, she said.

The CDC and the USDA are both involved in further investigations of the poultry farm outbreak. CDC’s Shah noted that the team the agency deployed to Colorado included an industrial hygienist, who can work on strategies to prevent further transmission.

To date, at least 161 herds in 13 states have tested positive for avian influenza since the dairy outbreak was confirmed in March. Since January 2022, when US birds first tested positive for the H5N1 virus, 99 million birds in the US have been affected in 48 states, which involved 1,165 individual outbreaks.

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Elon Musk says SpaceX and X will relocate their headquarters to Texas

California, elon musk, Gavin Newsom, Science, Space, spacex, texas, X / /

Home base at Starbase —

The billionaire blamed a California gender identity law for moving SpaceX and X headquarters.

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A pedestrian walks past a flown Falcon 9 booster at SpaceX headquarters in Hawthorne, California, on Tuesday, the same day Elon Musk said he will relocate the headquarters to Texas.

Enlarge / A pedestrian walks past a flown Falcon 9 booster at SpaceX headquarters in Hawthorne, California, on Tuesday, the same day Elon Musk said he will relocate the headquarters to Texas.

Elon Musk said Tuesday that he will move the headquarters of SpaceX and his social media company X from California to Texas in response to a new gender identity law signed by California Governor Gavin Newsom.

Musk’s announcement, made via a post on X, follows his decision in 2021 to move the headquarters of the electric car company Tesla from Palo Alto, California, to Austin, Texas, in the wake of coronavirus lockdowns in the Bay Area the year before. Now, two of Musk’s other major holdings are making symbolic moves out of California: SpaceX to the company’s Starbase launch facility near Brownsville, Texas, and X to Austin.

The new gender identity law, signed by Governor Newsom, a Democrat, on Monday, bars school districts in California from requiring teachers to disclose a change in a student’s gender identification or sexual orientation to their parents without the child’s permission. Musk wrote on X that the law was the “final straw” prompting the relocation to Texas, where the billionaire executive and his companies could take advantage of lower taxes and light-touch regulations.

Earlier this year, SpaceX transferred its incorporation from Delaware to Texas after a Delaware judge invalidated his pay package at Tesla.

“Because of this law and the many others that preceded it, attacking both families and companies, SpaceX will now move its HQ from Hawthorne, California, to Starbase, Texas,” Musk wrote Tuesday on X.

The first-in-the-nation law in California is a flashpoint in the struggle between conservative school boards concerned about parental rights and proponents for the privacy rights of LGBTQ people.

“I did make it clear to Governor Newsom about a year ago that laws of this nature would force families and companies to leave California to protect their children,” wrote Musk, who on Saturday endorsed former President Donald Trump, the Republican nominee in this year’s presidential election.

In a statement, Newsom’s office said the law “does not allow a student’s name or gender identity to be changed on an official school record without parental consent” and “does not take away or undermine parents’ rights.”

What does this mean for SpaceX?

Musk’s comments on X didn’t mention details about the implications of his companies’ moves to Texas. However, while Tesla’s corporate headquarters relocated to Texas in 2021, the company still produces cars in California and announced a new engineering hub in Palo Alto last year. The situation with SpaceX is likely to be similar.

Since Musk bought Twitter in 2022, he renamed it X, rewrote the network’s policies on content moderation, and laid off most of the company’s staff, reducing its workforce to around 1,500 employees. With vast manufacturing capacities, SpaceX currently has more than 13,000 employees, so a relocation for Musk’s space company would affect more people and potentially be more disruptive than one at X.

SpaceX’s current headquarters in Hawthorne, California, serves as a factory, engineering design center, and mission control for the company’s rockets and spacecraft. Relocating these facilities wouldn’t be easy, but SpaceX may not need to.

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Meet the woman whose research helped the FBI catch notorious serial killers

Ann Burgess, behavioral sciences, criminal psychology, culture, documentaries, fbi, forensic science, Hulu, Mindhunter, Science, serial killers, streaming television, true crime documentary / /
Dr. Ann Burgess helps the FBI catch serial killers in Hulu's <em>Mastermind: To Think Like a Killer.</em>” src=”https://cdn.arstechnica.net/wp-content/uploads/2024/07/mastermind5-800×535.jpg”></img><figcaption> <p><a data-height=Enlarge / Dr. Ann Burgess helps the FBI catch serial killers in Hulu’s Mastermind: To Think Like a Killer.

YouTube/Hulu

Fans of the Netflix series Mindhunter might recall the character of Dr. Wendy Carr (Anna Torv), a psychologist who joins forces with FBI criminal profilers to study the unique psychology of serial killers in hopes of more effectively catching them. But they might not know about the inspiration for the character: Dr. Ann Wolbert Burgess, whose long distinguished career finally gets the attention it deserves in a new documentary from Hulu, Mastermind: To Think Like a Killer.

Burgess herself thought it was “fun” to see a fictional character based on her but noted that Hollywood did take some liberties. “They got it wrong,” she told Ars. “They made me a psychologist. I’m a nurse”—specifically, a forensic and psychiatric nurse who pioneered research on sex crimes, victimology, and criminal psychology.

Mastermind should go a long way toward setting things right. Hulu brought on Abby Fuller to direct, best known for her work on the Chef’s Table series for Netflix. Fuller might seem like a surprising choice for making a true crime documentary, but the streamer thought she would bring a fresh take to a well-worn genre. “I love the true crime aspects, but I thought we could do something more elevated and cinematic and really make this a character-driven piece about [Ann], with true crime elements,” Fuller told Ars.

There’s no doubt that the public has a rather morbid fascination with serial killers, and Burgess certainly has had concerns about the way media coverage and Hollywood films have turned murderers into celebrities. “Despite how obviously horrible these killers were, despite their utter brutality and the pain they inflicted upon their victims, they’d somehow become romanticized,” Burgess wrote in her memoir, A Killer by Design: Murderers, Mindhunters, and My Quest to Decipher the Criminal Mind. “All the inconvenient details that interfered with this narrative—the loss of life, issues of mental health, and the victims themselves—were simply ignored.”

Mastermind.” height=”429″ src=”https://cdn.arstechnica.net/wp-content/uploads/2024/07/mastermind6-640×429.jpg” width=”640″>

Enlarge / A re-creation of Dr. Ann Burgess listening to taped interviews of serial killers in Mastermind.

YouTube/Hulu

That said, it’s not like anyone who finds the twisted psychology of serial killers, or true crime in general, fascinating is a sociopath or murderer in the making. “I think we all grapple with light and dark and how we see it in the world,” said Fuller. “There’s an inherent fascination with what makes someone who they are, with human behavior. And if you’re interested in human behavior, a serial killer exhibits some of the more fascinating behavior that exists. Trying to grasp the darkest of the dark and understand it is a way to ensure we never become it.”

“I think it’s a human factor,” Burgess said. “I don’t see anything wrong with it. There is a fascination to try to understand why people commit these horrifying crimes. How can people do these things? But I also think people like to play detective a little bit. I think that’s normal. You don’t want to be fooled; you don’t want to become a victim. So what can you learn to avoid it?”

For Burgess, it has always been about the victims. She co-founded one of the first crisis counseling programs at Boston City Hospital in the 1970s with Boston College sociologist Lynda Lytle Holmstrom. The duo conducted research on the emotional and traumatic effects of sexual violence, interviewing nearly 150 rape victims in the process. They were the first to realize that rape was about power and control rather than sex, and coined the term “rape trauma syndrome” to describe the psychological after-effects.

(WARNING: Some graphic details about violent crimes below.)

Dr. Ann Burgess research helped legitimize the FBI's Behavioral Sciences Unit.

Enlarge / Dr. Ann Burgess research helped legitimize the FBI’s Behavioral Sciences Unit.

Hulu

Their work caught the attention of Roy Hazelwood of the FBI, who invited Burgess to the FBI Academy in Quantico, Virginia, to give lectures to agents in the fledgling Behavioral Sciences Unit (BSU) on victimology and violent sex crimes. Thus began a decades-long collaboration that established criminal profiling as a legitimate practice in law enforcement.

Meet the woman whose research helped the FBI catch notorious serial killers Read More »

seismic-data-shows-mars-is-often-pummeled-by-planet-shaking-meteorites

Seismic data shows Mars is often pummeled by planet-shaking meteorites

astronomy, Impacts, Mars, meteorites, planetary science, Science, seismology / /

Brace for impact —

Seismic information now allows us to make a planet-wide estimate of impact rates.

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One of the craters identified seismically, then confirmed through orbital images.

Enlarge / One of the craters identified seismically, then confirmed through orbital images.

Mars trembles with marsquakes, but not all of them are driven by phenomena that occur beneath the surface—many are the aftermath of meteorite strikes.

Meteorites crash down to Mars every day. After analyzing data from NASA’s InSight lander, an international team of researchers noticed that its seismometer, SEIS, detected six nearby seismic events. These were linked to the same acoustic atmospheric signal that meteorites generate when whizzing through the atmosphere of Mars. Further investigation identified all six as part of an entirely new class of quakes known as VF (very high frequency) events.

The collisions that generate VF marsquakes occur in fractions of a second, much less time than the few seconds it takes tectonic processes to cause quakes similar in size. This is some of the key seismological data that has helped us understand the occurrence of earthquakes caused by meteoric impacts on Mars. This is also the first time seismic data was used to determine how frequently impact craters are formed.

“Although a non-impact origin cannot be definitively excluded for each VF event, we show that the VF class as a whole is plausibly caused by meteorite impacts,” the researchers said in a study recently published in Nature.

Seismic shift

Scientists had typically determined the approximate meteorite impact rate on Mars by comparing the frequency of craters on its surface to the expected rate of impacts calculated using counts of lunar craters that were left behind by meteorites. Models of the lunar cratering rate were then adjusted to fit Martian conditions.

Looking to the Moon as a basis for comparison was not ideal, as Mars is especially prone to being hit by meteorites. The red planet is not only a more massive body that has greater gravitational pull, but it is located near the asteroid belt.

Another issue is that lunar craters are often better preserved than Martian craters because there is no place in the Solar System dustier than Mars. Craters in orbital images are often partly obscured by dust, which makes them difficult to identify. Sandstorms can complicate matters by covering craters in more dust and debris (something that cannot occur on the Moon due to the absence of wind).

InSight deployed its SEIS instrument after it landed in the Elysium Planitia region of Mars. In addition to detecting tectonic activity, the seismometer can potentially determine the impact rate through seismic data. When meteorites strike Mars, they produce seismic waves just like tectonic marsquakes do, and the waves can be detected by seismometers when they travel through the mantle and crust. An immense quake picked up by SEIS was linked to a crater 150 meters (492 feet) wide. SEIS would later detect five more marsquakes that were all associated with an acoustic signal (detected by a different sensor on InSight) that is a telltale sign of a falling meteorite.

A huge impact

Something else stood out about the six impact-driven marsquakes detected with seismic data. Because of the velocity of meteorites (over 3,000 meters or 9,842 feet per second), these events happened faster than any other type of marsquake, even faster than quakes in the high frequency (HF) class. That’s how they earned their own classification: very high frequency, or VF, quakes. When the InSight team used the Mars Reconnaissance Orbiter’s (MRO) Context Camera (CTX) to image the locations of the events picked up by SEIS, there were new craters present in the images.

There are additional seismic events that haven’t been assigned to craters yet. They are thought to be small craters formed by meteorites about the size of basketballs, which are extremely difficult to see in orbital images from MRO.

The researchers were able to use SEIS data to estimate the diameters of craters based on distance from InSight (according to how long it took seismic waves to reach the spacecraft) and the magnitude of the VF marsquakes associated with them. They were also able to derive the frequency of quakes picked up by SEIS. Once a frequency estimate based on the data was applied to the entire surface area of Mars, they estimated that around 280 to 360 VF quakes occur each year.

“The case is strong that the unique VF marsquake class is consistent with impacts,” they said in the same study. “It is, therefore, worthwhile considering the implications of attributing all VF events to meteoroid impacts.”

Their detection has added to the estimated number of impact craters on Mars since many could not be seen from space before. What can VF impacts tell us? The impact rate on a planet or moon is important for determining the age of that object’s surface. Using impacts has helped us determine that the surface of Venus is constantly being renewed by volcanic activity, while most of the surface of Mars has not been covered in lava for billions of years.

Figuring out the rate of meteorite impacts can also help protect spacecraft and, someday, maybe Martian astronauts, from potential hazards. The study suggests that there are periods where impacts are more or less frequent, so it might be possible to predict when the sky is a bit more likely to be clear of falling space rocks—and when it isn’t. Meteorites are not much of a danger to Earth since most of them burn up in the atmosphere. Mars has a much thinner atmosphere that more can make it through, and there is no umbrella for a meteor shower.

Nature Astronomy, 2024. DOI: 10.1038/s41550-024-02301-z

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