Science

researchers-build-ultralight-drone-that-flies-with-onboard-solar

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.

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

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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.

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

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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 »

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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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The struggle to understand why earthquakes happen in America’s heartland

earthquakes, New Madrid fault, Science, seismology, syndication / /
Top: A view of the downtown Memphis skyline, including the Hernando De Soto bridge which has been retrofitted for earthquakes. Memphis is located around 40 miles from a fault line in the quake-prone New Madrid system.

Enlarge / Top: A view of the downtown Memphis skyline, including the Hernando De Soto bridge which has been retrofitted for earthquakes. Memphis is located around 40 miles from a fault line in the quake-prone New Madrid system.

iStock via Getty Images

The first earthquake struck while the town was still asleep. Around 2: 00 am on Dec. 16, 1811, New Madrid—a small frontier settlement of 400 people on land now located in Missouri—was jolted awake. Panicked townsfolk fled their homes as buildings collapsed and the smell of sulfur filled the air.

The episode didn’t last long. But the worst was yet to come. Nearly two months later, after dozens of aftershocks and another massive quake, the fault line running directly under the town ruptured. Thirty-one-year-old resident Eliza Bryan watched in horror as the Mississippi River receded and swept away boats full of people. In nearby fields, geysers of sand erupted, and a rumble filled the air.

In the end, the town had dropped at least 15 feet. Bryan and others spent a year and a half living in makeshift camps while they waited for the aftershocks to end. Four years later, the shocks had become less common. At last, the rattled townspeople began “to hope that ere long they will entirely cease,” Bryan wrote in a letter.

Whether Bryan’s hope will stand the test of time is an open question.

The US Geological Survey released a report in December 2023 detailing the risk of dangerous earthquakes around the country. As expected on the hazard map, deep red risk lines run through California and Alaska. But the map also sports a big bull’s eye in the middle of the country—right over New Madrid.

The USGS estimates that the region has a 25 to 40 percent chance of a magnitude 6.0 or higher earthquake in the next 50 years, and as much as a 10 percent chance of a repeat of the 1811-1812 sequence. While the risk is much lower compared to, say, California, experts say that when it comes to earthquake resistance, the New Madrid region suffers from inadequate building codes and infrastructure.

Caught in this seismic splash zone are millions of people living across five states—mostly in Tennessee and Missouri, as well as Kentucky, Illinois, and Arkansas—including two major cities, Memphis and St. Louis. Mississippi, Alabama, and Indiana have also been noted as places of concern.

In response to the potential for calamity, geologists have learned a lot about this odd earthquake hotspot over the last few decades. Yet one mystery has persisted: why earthquakes even happen here in the first place.

This is a problem, experts say. Without a clear mechanism for why New Madrid experiences earthquakes, scientists are still struggling to answer some of the most basic questions, like when—or even if—another large earthquake will strike the region. In Missouri today, earthquakes are “not as front of mind” as other natural disasters, said Jeff Briggs, earthquake program manager for the Missouri State Emergency Management Agency.

But when the next big shake comes, “it’s going to be the biggest natural disaster this state has ever experienced.”

The struggle to understand why earthquakes happen in America’s heartland Read More »

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Will space-based solar power ever make sense?

Energy, renewable energy, Science, solar power, space-based solar / /
Artist's depiction of an astronaut servicing solar panels against the black background of space.

Is space-based solar power a costly, risky pipe dream? Or is it a viable way to combat climate change? Although beaming solar power from space to Earth could ultimately involve transmitting gigawatts, the process could be made surprisingly safe and cost-effective, according to experts from Space Solar, the European Space Agency, and the University of Glasgow.

But we’re going to need to move well beyond demonstration hardware and solve a number of engineering challenges if we want to develop that potential.

Designing space-based solar

Beaming solar energy from space is not new; telecommunications satellites have been sending microwave signals generated by solar power back to Earth since the 1960s. But sending useful amounts of power is a different matter entirely.

“The idea [has] been around for just over a century,” said Nicol Caplin, deep space exploration scientist at the ESA, on a Physics World podcast. “The original concepts were indeed sci-fi. It’s sort of rooted in science fiction, but then, since then, there’s been a trend of interest coming and going.”

Researchers are scoping out multiple designs for space-based solar power. Matteo Ceriotti, senior lecturer in space systems engineering at the University of Glasgow, wrote in The Conversation that many designs have been proposed.

The Solaris initiative is exploring two possible technologies, according to Sanjay Vijendran, lead for the Solaris initiative at the ESA: one that involves beaming microwaves from a station in geostationary orbit down to a receiver on Earth and another that involves using immense mirrors in a lower orbit to reflect sunlight down onto solar farms. He said he thinks that both of these solutions are potentially valuable. Microwave technology has drawn wider interest and was the main focus of these interviews. It has enormous potential, although high-frequency radio waves can also be used.

“You really have a source of 24/7 clean power from space,” Vijendran said. The power can be transmitted regardless of weather conditions because of the frequency of the microwaves.

“A 1-gigawatt power plant in space would be comparable to the top five solar farms on earth. A power plant with a capacity of 1 gigawatt could power around 875,000 households for one year,” said Andrew Glester, host of the Physics World podcast.

But we’re not ready to deploy anything like this. “It will be a big engineering challenge,” Caplin said. There are a number of physical hurdles involved in successfully building a solar power station in space.

Using microwave technology, the solar array for an orbiting power station that generates a gigawatt of power would have to be over 1 square kilometer in size, according to a Nature article by senior reporter Elizabeth Gibney. “That’s more than 100 times the size of the International Space Station, which took a decade to build.” It would also need to be assembled robotically, since the orbiting facility would be uncrewed.

The solar cells would need to be resilient to space radiation and debris. They would also need to be efficient and lightweight, with a power-to-weight ratio 50 times more than the typical silicon solar cell, Gibney wrote. Keeping the cost of these cells down is another factor that engineers have to take into consideration. Reducing the losses during power transmission is another challenge, Gibney wrote. The energy conversion rate needs to be improved to 10–15 percent, according to the ESA. This would require technical advances.

Space Solar is working on a satellite design called CASSIOPeiA, which Physics World describes as looking “like a spiral staircase, with the photovoltaic panels being the ‘treads’ and the microwave transmitters—rod-shaped dipoles—being the ‘risers.’” It has a helical shape with no moving parts.

“Our system’s comprised of hundreds of thousands of the same dinner-plate-sized power modules. Each module has the PV which converts the sun’s energy into DC electricity,” said Sam Adlen, CEO of Space Solar.

“That DC power then drives electronics to transmit the power… down toward Earth from dipole antennas. That power up in space is converted to [microwaves] and beamed down in a coherent beam down to the Earth where it’s received by a rectifying antenna, reconverted into electricity, and input to the grid.”

Adlen said that robotics technologies for space applications, such as in-orbit assembly, are advancing rapidly.

Ceriotti wrote that SPS-ALPHA, another design, has a large solar-collector structure that includes many heliostats, which are modular small reflectors that can be moved individually. These concentrate sunlight onto separate power-generating modules, after which it’s transmitted back to Earth by yet another module.

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animals-use-physics?-let-us-count-the-ways

Animals use physics? Let us count the ways

biological physics, Science, syndication / /
kitten latches on to a pole with its two front paws

Isaac Newton would never have discovered the laws of motion had he studied only cats.

Suppose you hold a cat, stomach up, and drop it from a second-story window. If a cat is simply a mechanical system that obeys Newton’s rules of matter in motion, it should land on its back. (OK, there are some technicalities—like this should be done in a vacuum, but ignore that for now.) Instead, most cats usually avoid injury by twisting themselves on the way down to land on their feet.

Most people are not mystified by this trick—everybody has seen videos attesting to cats’ acrobatic prowess. But for more than a century, scientists have wondered about the physics of how cats do it. Clearly, the mathematical theorem analyzing the falling cat as a mechanical system fails for live cats, as Nobel laureate Frank Wilczek points out in a recent paper.

“This theorem is not relevant to real biological cats,” writes Wilczek, a theoretical physicist at MIT. They are not closed mechanical systems, and can “consume stored energy … empowering mechanical motion.”

Nevertheless, the laws of physics do apply to cats—as well as every other kind of animal, from insects to elephants. Biology does not avoid physics; it embraces it. From friction on microscopic scales to fluid dynamics in water and air, animals exploit physical laws to run or swim or fly. Every other aspect of animal behavior, from breathing to building shelters, depends in some way on the restrictions imposed, and opportunities permitted, by physics.

“Living organisms are … systems whose actions are constrained by physics across multiple length scales and timescales,” Jennifer Rieser and coauthors write in the current issue of the Annual Review of Condensed Matter Physics.

While the field of animal behavior physics is still in its infancy, substantial progress has been made in explaining individual behaviors, along with how those behaviors are shaped via interactions with other individuals and the environment. Apart from discovering more about how animals perform their diverse repertoire of skills, such research may also lead to new physics knowledge gained by scrutinizing animal abilities that scientists don’t yet understand.

Critters in motion

Physics applies to animals in action over a wide range of spatial scales. At the smallest end of the range, attractive forces between nearby atoms facilitate the ability of geckos and some insects to climb up walls or even walk on ceilings. On a slightly larger scale, textures and structures provide adhesion for other biological gymnastics. In bird feathers, for instance, tiny hooks and barbs act like Velcro, holding feathers in position to enhance lift when flying, Rieser and colleagues report.

Biological textures also aid movement by facilitating friction between animal parts and surfaces. Scales on California king snakes possess textures that allow rapid forward sliding, but increase friction to retard backward or sideways motion. Some sidewinding snakes have apparently evolved different textures that reduce friction in the direction of motion, recent research suggests.

Small-scale structures are also important for animals’ interaction with water. For many animals, microstructures make the body “superhydrophobic”—capable of blocking the penetration of water. “In wet climates, water droplet shedding can be essential in animals, like flying birds and insects, where weight and stability are crucially important,” note Rieser, of Emory University, and coauthors Chantal Nguyen, Orit Peleg and Calvin Riiska.

Water-blocking surfaces also help animals keep their skins clean. “This self-cleansing mechanism … can be important to help protect the animal from dangers like skin-borne parasites and other infections,” the Annual Review authors explain. And in some cases, removing foreign material from an animal’s surface may be necessary to preserve the surface properties that enhance camouflage.

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in-the-south,-sea-level-rise-accelerates-at-some-of-the-most-extreme-rates-on-earth

In the South, sea level rise accelerates at some of the most extreme rates on Earth

climate change, coastal flooding, Florida, rising sea level, Science, syndication / /

migrating inland —

The surge is startling scientists, amplifying impacts such as hurricane storm surges.

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Older man points to the rising tide while standing on a dock.

Enlarge / Steve Salem is a 50-year boat captain who lives on a tributary of the St. Johns River. The rising tides in Jacksonville are testing his intuition.

This article originally appeared on Inside Climate News, a nonprofit, independent news organization that covers climate, energy, and the environment. It is republished with permission. Sign up for their newsletter here. 

JACKSONVILLE, Fla.—For most of his life, Steve Salem has led an existence closely linked with the rise and fall of the tides.

Salem is a 50-year boat captain who designed and built his 65-foot vessel by hand.

“Me and Noah, we’re related somewhere,” said Salem, 75, whose silver beard evokes Ernest Hemingway.

Salem is familiar with how the sun and moon influence the tides and feels an innate sense for their ebb and flow, although the tides here are beginning to test even his intuition.

He and his wife live in a rust-colored ranch-style house along a tributary of the St. Johns River, Florida’s longest. Before they moved in the house had flooded, in 2017, as Hurricane Irma swirled by. The house flooded again in 2022, when Hurricane Nicole defied his expectations. But Salem believes the house is sturdy and that he can manage the tides, as he always has.

“I’m a water dog to begin with. I’ve always been on the water,” said Salem, who prefers to go by Captain Steve. “I worry about things that I have to do something about. If I can’t do anything about it, then worrying about it is going to do what?”

Across the American South, tides are rising at accelerating rates that are among the most extreme on Earth, constituting a surge that has startled scientists such as Jeff Chanton, professor in the Department of Earth, Ocean and Atmospheric Science at Florida State University.

“It’s pretty shocking,” he said. “You would think it would increase gradually, it would be a gradual thing. But this is like a major shift.”

Worldwide sea levels have climbed since 1900 by some 1.5 millimeters a year, a pace that is unprecedented in at least 3,000 years and generally attributable to melting ice sheets and glaciers and also the expansion of the oceans as their temperatures warm. Since the middle of the 20th century the rate has gained speed, exceeding 3 millimeters a year since 1992.

In the South the pace has quickened further, jumping from about 1.7 millimeters a year at the turn of the 20th century to at least 8.4 millimeters by 2021, according to a 2023 study published in Nature Communications based on tidal gauge records from throughout the region. In Pensacola, a beachy community on the western side of the Florida Panhandle, the rate soared to roughly 11 millimeters a year by the end of 2021.

“I think people just really have no idea what is coming, because we have no way of visualizing that through our own personal experiences, or that of the last 250 years,” said Randall Parkinson, a coastal geologist at Florida International University. “It’s not something where you go, ‘I know what that might look like because I’ve seen that.’ Because we haven’t.

“It’s the same everywhere, from North Carolina all the way down to the Florida Keys and all the way up into Alabama,” he said. “All of these areas are extremely vulnerable.”

The acceleration is poised to amplify impacts such as hurricane storm surges, nuisance flooding and land loss. In recent years the rising tides have coincided with record-breaking hurricane seasons, pushing storm surges higher and farther inland. In 2022 Hurricane Ian, which came ashore in southwest Florida, was the costliest hurricane in state history and third-costliest to date in the United States, after Katrina in 2005 and Harvey in 2017.

“It doesn’t even take a major storm event anymore. You just get these compounding effects,” said Rachel Cleetus, a policy director at the Union for Concerned Scientists, an advocacy group. “All of a sudden you have a much more impactful flooding event, and a lot of the infrastructure, frankly, like the stormwater infrastructure, it’s just not built for this.”

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nato-allies-pledge-$1-billion-to-promote-sharing-of-space-based-intel

NATO allies pledge $1 billion to promote sharing of space-based intel

military space, Nato, nato summit, Science, Space / /

Breaking barriers —

Agreement marks the largest investment in space-based capabilities in NATO’s history.

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Heads of state pose for a group photo at an event Tuesday celebrating the 75th anniversary of NATO.

Enlarge / Heads of state pose for a group photo at an event Tuesday celebrating the 75th anniversary of NATO.

During their summit in Washington, DC, this week, NATO member states committed more than $1 billion to improve the sharing of intelligence from national and commercial reconnaissance satellites.

The agreement is a further step toward integrating space assets into NATO military commands. It follows the bloc’s adoption of an official space policy in 2019, which recognized space as a fifth war-fighting domain alongside air, land, maritime, and cyberspace. The next step was the formation of the NATO Space Operations Center in 2020 to oversee space support for NATO military operations.

On June 25, NATO announced the establishment of a “space branch” in its Allied Command Transformation, which identifies trends and incorporates emerging capabilities into the alliance’s security strategy.

Breaking down barriers

The new intelligence-sharing agreement was signed on July 9 by representatives from 17 NATO nations, including the United States, to support the Alliance Persistent Surveillance from Space (APSS) program. In a statement, NATO called the agreement “the largest multinational investment in space-based capabilities in NATO’s history.”

The agreement for open sharing of intelligence data comes against the backdrop of NATO’s response to the Russian invasion of Ukraine. Space-based capabilities, including battlefield surveillance and communications, have proven crucial to both sides in the war.

“The ongoing war in Ukraine has further underscored intelligence’s growing dependence on space-based data and assets,” NATO said.

The program will improve NATO’s ability to monitor activities on the ground and at sea with unprecedented accuracy and timeliness, the alliance said in a statement. The 17 parties to the agreement pledged more than $1 billion transition the program into an implementation phase over the next five years. Six of the 17 signatories currently operate or plan to launch their own national reconnaissance satellites, while several more nations are home to companies operating commercial space-based surveillance satellites.

The APSS program won’t involve the development and launch of any NATO spy satellites. Instead, each nation will make efforts to share observations from their own government and commercial satellites.

Luxembourg, one of the smallest NATO member states, set up the APSS program with an initial investment of roughly $18 million (16.5 million euros) in 2023. At the time, NATO called the program a “data-centric initiative” aimed at bringing together intelligence information for easier dissemination among allies and breaking down barriers of secrecy and bureaucracy.

“APSS is not about creating NATO-owned and operated space assets,” officials wrote in the program’s fact sheet. “It will make use of existing and future space assets in allied countries, and connect them together in a NATO virtual constellation called ‘Aquila.'”

Another element of the program involves processing and sharing intelligence information through cloud solutions and technologies. NATO said AI analytical tools will also better manage growing amounts of surveillance data from space, and ensure decision-makers get faster access to time-sensitive observations.

“The APSS initiative may be regarded as a game changer for NATO’s intelligence, surveillance and reconnaissance. It will largely contribute to build NATO’s readiness and reduce its dependency on other intelligence and surveillance capabilities,” said Ludwig Decamps, general manager of the NATO Communications and Information Agency.

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500-million-year-old-fossil-is-the-earliest-branch-of-the-spider’s-lineage

500 million-year-old fossil is the earliest branch of the spider’s lineage

arthropods, Biology, evolution, paleontology, Science, spiders / /

Creepy, but no longer crawly —

A local fossil collector in Morocco found the specimen decades ago.

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Image of a brown fossil with a large head and many body segments, embedded in a grey-green rock.

In the early 2000s, local fossil collector Mohamed ‘Ou Said’ Ben Moula discovered numerous fossils at Fezouata Shale, a site in Morocco known for its well-preserved fossils from the Early Ordovician period, roughly 480 million years ago. Recently, a team of researchers at the University of Lausanne (UNIL) studied 100 of these fossils and identified one of them as the earliest ancestor of modern-day chelicerates, a group that includes spiders, scorpions, and horseshoe crabs.

The fossil preserves the species Setapedites abundantis, a tiny animal that crawled and swam near the bottom of a 100–200-meter-deep ocean near the South Pole 478 million years ago. It was 5 to 10 millimeters long and fed on organic matter in the seafloor sediments. “Fossils of what is now known as S. abundantis have been found early on—one specimen mentioned in the 2010 paper that recognized the importance of this biota. However, this creature wasn’t studied in detail before simply because scientists focused on other taxa first,” Pierre Gueriau, one of the researchers and a junior lecturer at UNIL, told Ars Technica.

The study from Gueriau and his team is the first to describe S. abundantis and its connection to modern-day chelicerates (also called euchelicerates). It holds great significance, because “the origin of chelicerates has been one of the most tangled knots in the arthropod tree of life, as there has been a lack of fossils between 503 to 430 million years ago,” Gueriau added.

An ancestor of spiders

The study authors used X-ray scanners to reconstruct the anatomy of 100 fossils from the Fezouata Shale in 3D. When they compared the anatomical features of these ancient animals with those of chelicerates, they noticed several similarities between S. abundantis and various ancient and modern-day arthropods, including horseshoe crabs, scorpions, and spiders.

For instance, the nature and arrangement of the head appendages or ‘legs’ in S. abundantis were homologous with those of present-day horseshoe crabs and Cambrian arthropods that existed between 540 to 480 million years ago. Moreover, like spiders and scorpions, the organism exhibited body tagmosis, where the body is organized into different functional sections.

“Setapedites abundantis contributes to our understandings of the origin and early evolution of two key euchelicerate characters: the transition from biramous to uniramous prosomal appendages, and body tagmosis,” the study authors note.

Currently, two Cambrian-era arthropods, Mollisonia plenovenatrix and Habelia optata are generally considered the earliest ancestors of chelicerates (not all scientists accept this idea). Both lived around 500 million years ago. When we asked how these two differ from S. abundantis, Gueriau replied, “Habelia and Mollisonia represent at best early-branching lineages in the phylogenetic tree. While S. abundantis is found to represent, together with a couple of other fossils, the earliest branching lineage within chelicerates.”

This means Habelia and Mollisonia are relatives of the ancestors of modern-day chelicerates. On the other side, S. abundantis represents the first group that split after the chelicerate clade was established, making it the earliest member of the lineage. “These findings bring us closer to untangling the origin story of arthropods, as they allow us to fill the anatomical gap between Cambrian arthropods and early-branching chelicerates,” Gueriau told Ars Technica.

S. abundantis connects other fossils

The researchers faced many challenges during their study. For instance, the small size of the fossils made observations and interpretation complicated. They overcame this limitation by examining a large number of specimens—fortunately, S. abundantis fossils were abundant in the samples they studied. However, these fossils have yet to reveal all their secrets.

“Some of S. abundantis’ anatomical features allow for a deeper understanding of the early evolution of the chelicerate group and may even link other fossil forms, whose relationships are still highly debated, to this group,” Gueriau said. For instance, the study authors noticed a ventral protrusion at the rear of the organism. Such a feature is observed for the first time in chelicerates but is known in other primitive arthropods.

“This trait could thus bring together many other fossils with chelicerates and further resolve the early branches of the arthropod tree. So the next step for this research is to investigate deeper this feature on a wide range of fossils and its phylogenetic implications,” Gueriau added.

Nature Communications, 2023. DOI: 10.1038/s41467-024-48013-w  (About DOIs)

Rupendra Brahambhatt is an experienced journalist and filmmaker. He covers science and culture news, and for the last five years, he has been actively working with some of the most innovative news agencies, magazines, and media brands operating in different parts of the globe.

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