How balloons could one day detect quakes on Venus

The balloon was floating over the Pacific Ocean when the first sound waves hit. For 11 seconds, a tiny device dangling beneath the large, transparent balloon recorded sudden, jerky fluctuations in air pressure: echoes of an earthquake more than 2,800 kilometers away.

That scientific instrument was one of four hovering high above the Malay Archipelago on December 14, 2021. That day the quartet became the first network of devices to monitor an earthquake from the air, researchers report in the Aug. 16 Geophysical Research Letters.
The finding could help scientists track earthquakes in remote areas on Earth, and also opens the door to one day sending specially equipped balloons to study the geology of other worlds, including our closest planetary neighbor.

“Venus is the sister planet of Earth, but it’s the evil twin sister,” says David Mimoun, a planetary scientist at the University of Toulouse in France. “We don’t know why the two planets are so different. That’s why we need measurements.”

The idea of using balloons to study far-off rumblings on Earth has its roots in the Cold War. In the 1940s, the U.S. military launched a top secret project to spy on Soviet nuclear weapons testing using microphones attached to balloons floating high in the atmosphere. When the ground shakes, it releases low-frequency sound waves that can travel long distances in the atmosphere. The military planned on using the microphones to pick up on the sound of the ground shaking from a nuclear explosion. But the project was eventually deemed too expensive and dropped — though not before one of the balloons crashed in New Mexico, launching the Roswell conspiracy.

For decades after, balloon science stayed mostly in the realm of meteorology. Then in the early 2000s, Mimoun and his colleagues started experimenting with using balloons for space exploration, specifically for studying extraterrestrial quakes.

Analyzing temblors is one of the main ways that scientists can learn about a planet’s interior. On worlds with thin atmospheres, such as Mars or Earth’s moon, this generally means sending a lander to the surface and measuring quakes directly on the ground (SN: 5/13/22).

But doing that on Venus isn’t really an option. The dense atmosphere means that the planet’s surface has about the same pressure as Earth’s deep ocean, with temperatures averaging around 450° Celsius — hot enough to melt lead. “Basically, it’s hell,” Mimoun says.

Landers have made it to the surface of Venus before (SN: 6/19/76). But these probes lasted only a few hours before succumbing to the extreme heat and pressure. The chances of measuring a quake in that short time frame are slim, says Siddharth Krishnamoorthy, a research technologist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who wasn’t involved in the study. So while radar images of Venus have revealed a world dotted with volcanoes, scientists still don’t know for sure if Venus is geologically active, he says.

Scientists have previously experimented with the idea of detecting quakes on Venus using orbiters (SN: 9/02/05). But quake-detecting balloons have better resolution, says Mimoun, meaning they could provide the key to revealing the planet’s interior life. But first Mimoun and his colleagues had to show that they could design devices small enough to be carried by balloons but sensitive enough to pick up earthquakes far below.

In 2021, the team attached micro-barometers to 16 balloons launched from the Seychelles Islands, off the coast of East Africa. In December, four balloons — having drifted thousands of kilometers apart — recorded similar, low-frequency sound waves. These changes in air pressure resembled ground readings of a 7.3 magnitude earthquake near the Indonesian island of Flores, indicating that the sound waves were produced by the earthquake. The researchers were able to use the changes in air pressure to pinpoint the epicenter of the quake and calculate its magnitude.
“This is a huge step forward in demonstrating the utility of this technology,” says Paul Byrne, a planetary scientist at Washington University in St. Louis, who was not involved with the study.

Even without being able to pick up quakes, the balloons, if designed to survive in the Venusian atmosphere, might be able to detect changes in air pressure that reveal clues about the planet’s volcanic eruptions and mysterious highlands, Byrne says.

Venus is entering a renaissance of interest from space agencies. At least two NASA missions to visit the planet are planned for the end of this decade (SN: 6/2/21). Mimoun is hoping that earthquake-detecting balloons will feature in the next major mission, emphasizing that their data could help researchers understand why Earth and Venus — alike in size and distance from the sun, relative to the other planets — have gone down such different paths.

“We have no clue,” Mimoun says. “So we need to go back.”

Mammal ancestors’ shrinking inner ears may reveal when warm-bloodedness arose

Hot or not? Peeking inside an animal’s ear — even a fossilized one — may tell you whether it was warm- or cold-blooded. Using a novel method that analyzes the size and shape of the inner ear canals, researchers suggest that mammal ancestors abruptly became warm-blooded about 233 million years ago, the team reports in Nature July 20.

Warm-bloodedness, or endothermy, isn’t unique to mammals — birds, the only living dinosaurs, are warm-blooded, too. But endothermy is one of mammals’ key features, allowing the animals to regulate their internal body temperatures by controlling their metabolic rates. This feature allowed mammals to occupy environmental niches from pole to equator, and to weather the instability of ancient climates (SN: 6/7/22).
When endothermy evolved, however, has been a mystery. Based on fossil analyses of growth rates and oxygen isotopes in bones, researchers have proposed dates for its emergence as far back as 300 million years ago.

The inner ear structures of mammals and their ancestors hold the key to solving that mystery, says Ricardo Araújo, a vertebrate paleontologist at the University of Lisbon. In all vertebrates, the labyrinth of semicircular canals in the inner ear contains a fluid that responds to head movements, brushing against tiny hair cells in the ear and helping to maintain a sense of balance. That fluid can become thicker or thinner depending on body temperature.

“Mammals have very unique inner ears,” Araújo says. Compared with cold-blooded vertebrates of similar size, the dimensions of mammals’ semicircular canals — such as thickness, length and radius of curvature — is particularly small, he says. “The ducts are very thin and tend to be very circular compared with other animals.” By contrast, fish have the largest for their body size.

What if, Araújo and his colleagues hypothesized, the size and shape of the ear canals are related to the animal’s body temperature? In warm-blooded animals, the fluid becomes less viscous, and the canals may have shrunk to compensate. If so, it might be possible to trace how the shape of fossilized inner ear canals changed over time to discover when warm-bloodedness emerged in the mammal lineage.

To test that hypothesis, the researchers created a tool they call the “thermo-motility index” to link warm-bloodedness to those inner ear dimensions in 341 different vertebrates. Accounting for size differences, the value of this index turned out to closely track an animal’s body temperature, from fish to reptiles to mammals. Reptiles had low index values; mammals were high.

The team then applied this index to the fossilized ear canals of 56 extinct mammal ancestor species. To their surprise, the data showed a sharp change in inner ear morphology around 233 million years ago. That would correspond to an increase in body temperature of between 5 and 9 degrees Celsius — suggesting that endothermy evolved abruptly around that time, the team concludes.
“The fact that it is a sharp break in the data [suggests] the transition happened rapidly, within about a million years,” says coauthor Kenneth Angielczyk, a paleontologist at the Field Museum in Chicago.

It’s a clever study, says Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the work. “I’ve been using [computed tomography] data to study the shapes of inner ears for years, to try to infer how extinct species moved and how they could hear, and it never occurred to me that inner ear shape is related to metabolism and could be used to predict body temperatures of fossil species.”

However, Brusatte notes that there is a limit to what scientists can glean from fossilized ear canals alone, as they don’t reveal what soft tissues may have been present, such as the hair cells, or the actual viscosity of the ear fluid. “Shape alone may not always be sufficient to predict something as complex as body temperature or metabolic style.”

The timing of the purported shift, about 233 million years ago, corresponds to a geologically brief interlude of highly unstable climate known as the Carnian Pluvial Episode (SN: 9/30/21). “It was a time when global temperatures were changing a lot, and it was also a very wet, humid time,” Angielczyk says. “One of the benefits of endothermy is that it stabilizes the internal body environment, lets you operate independent of environmental conditions.”

The finding highlights how “the whole Triassic was a bit insane,” Araújo says. The start of the Triassic was epically hot, coming on the heels of the “Great Dying” mass extinction at the end of the Permian Period (SN: 12/6/18). Vertebrate species had just begun to recover from that event when they were hit with the Carnian Pluvial Episode. Yet the Triassic also saw the dawn of both mammals and dinosaurs — both of which managed to survive.

It was “a crucial time period in the history of life,” Araújo says. All of that instability may have armed both groups with the evolutionary tools they needed to weather yet another mass extinction at the end of the Triassic 201 million years ago (SN: 7/1/22).

Designer drugs hit dangerous lows to bring new highs

The 18-year-old had stabbed himself four times in the neck and chest with a pair of scissors. Alone in his dorm room, he had suddenly felt trapped, convinced that the only way to get out was to kill himself.

When he woke up hours later in a pool of blood, the psychedelic trip that had gripped him was waning. Horrified, he managed to call an ambulance. As he recovered, the college student told Joji Suzuki, an addiction psychiatrist at Brigham and Women’s Hospital in Boston, that he had taken LSD.
Suzuki was suspicious. Months earlier, in the summer of 2013, another student had come in with stab wounds in his back. He claimed to have taken magic mushrooms and said that he had stabbed himself. But psychedelic mushrooms don’t make people violent, and stabbing oneself in the back is not easy to do. Suzuki suspects that the young man with the back wound may have been covering for a friend who was also high. A month later the student was back. He spent five days delirious in the hospital’s intensive care unit, claiming he had taken LSD.

Violence and delirium are not usual effects of LSD. “Even in an overdose, LSD won’t lead to a five-day agitated delirium in the ICU,” Suzuki says. “I knew then that this had to be something else.”

By the time the scissors-wielding student arrived, Suzuki was better prepared. He had found a lab that could test for a little-known hallucinogen called 25I-NBOMe. Sure enough, the student’s blood tested positive. Maybe he thought he was taking LSD, but he had actually ingested a new, more dangerous hallucinogen from a family of drugs called smiles or NBOMes (pronounced en-bombs). People who take NBOMes are prone to stab themselves, says Suzuki, who reported the case in November in the Journal of Psychoactive Drugs. “We see it so many times. It’s bizarre.”

NBOMe overdoses have been appearing in U.S. emergency rooms since around 2012, but little is known about the drugs. They are one of many designer drugs, produced as alternatives for classic but illegal substances such as cocaine, LSD and marijuana. Some of the most popular designer drugs are hallucinogens such as NBOMes, stimulants such as bath salts (named for their resemblance to Epsom salts) and spice — synthetic cannabinoids that mimic marijuana. Each one comes in versions that are more dangerous than the drugs they were made to replace.

When a designer drug first appears for sale — often in gas stations, convenience stores or online — it is technically legal, because its chemical structure is slightly different from the illicit drug it mimics. When the U.S. Drug Enforcement Administration gets wind of the new drug, the agency moves to label the drug “Schedule 1,” meaning that it is not safe and has no known medical use. Dodgy chemists will then tweak the structure a bit and release another wave of slightly different, legal-until-they-get-noticed drugs.

Story continues after table
A lot of the drugs seen on the street today haven’t even been tested in animals, much less in humans, says Jenny Wiley, a behavioral pharmacologist at RTI International in Research Triangle Park, N.C. “People are basically the guinea pigs.”

Though designer drugs have been around for decades, there’s been a recent surge in new compounds, says Jill Head, a forensic chemist at a DEA research lab in Dulles, Va. “In the last five or six years we’ve seen upwards of 350, almost 400 new drugs emerge.”

And each one is somewhat different. “Every drug has its own little story,” says Michael Baumann, who heads the Designer Drug Research Unit, a small team within the National Institute on Drug Abuse in Baltimore. When a new drug appears, it’s up to chemists, pharmacologists and researchers like Baumann to quickly develop tests that will detect the drug in a person’s system and figure out how it works. They want to know the risks it poses and how best to treat people who have bad reactions.

Spicing up drug testing
Though recreational marijuana is legal in four states and the District of Columbia, synthetic cannabinoids are still in demand. Pot remains illegal for people under age 21. Plus, military personnel, police officers, parolees and athletes are all routinely screened for marijuana and other drugs. A big benefit of the newcomer drugs: Commonly used tests don’t look for them.

To improve such testing, Marilyn Huestis, a forensic toxicologist at NIDA, wants to identify the breakdown products of spice and other designer drugs. “The problem is that we’re always behind the manufacturers,” she says. “As quickly as a drug becomes [illegal], immediately other drugs are available on the market.”

To evaluate any new compound, she incubates a sample of the drug with pieces of human liver cells to see how long it takes the cells to break down the compound. The test “tells you something about the potential danger of that drug,” she says. A drug that is slowly metabolized “is going to be active in the body for a longer period of time.”

Huestis then investigates how the drug’s structure changes when the body metabolizes it. For a given drug, she generally finds 12 to 25 different metabolites and identifies the most common ones, so testers can focus on the easiest-to-find compounds in blood or urine samples.

Story continues after sidebar
Like many designer drugs, spice has its origins in the scientific literature, Huestis says. Researchers created synthetic cannabinoids in the 1980s as tools to understand the body’s endocannabinoid system, which is involved in learning, memory, appetite, fighting disease and pain. Chemists were trying to make a compound that could snugly fit into endocannabinoid receptors, proteins that sit on the outside of cells and act as the system’s gateway. They hoped that finding a key to unlock these receptors might lead to more effective painkillers.

“The folks that were making these never in their wildest dreams thought that [the compounds] would be diverted as drugs of abuse,” Baumann says.

But inevitably, clandestine chemists discovered how well synthetic cannabinoids replicate the effects of weed, and started pumping them out. The first five synthetic cannabinoids were declared illegal in 2011.

“People tend to think, well gee, cannabis really isn’t bad for you, how can these be bad for you? But the potency makes a tremendous difference,” Huestis says. Some forms of spice are up to 100 times as potent as weed — a small amount can have a big effect, she adds.

Though many people use the drugs without incident, some forms of spice can cause strokes, heart attacks and kidney damage, she says. Psychosis is also a big problem.

The rat brain on bath salts
Most of Baumann’s research has focused on bath salts, drugs designed to mimic a stimulant called cathinone. Cathinone occurs naturally in the khat plant, which grows on the Arabian Peninsula and in East Africa. Chewing the leaves gives a stimulating boost like that from drinking a cup of coffee, Baumann says. Synthesized by chemists, bath salts are more intense.

Typically sold as a powder, bath salts produce feelings of euphoria and alertness similar to the effects of amphetamines and cocaine, but some chemical forms are even more powerful. MDPV, the most infamous component of the original wave of bath salts, can bring on a powerful crash involving suicidal feelings, delirium and violence. This crash may happen because bath salts thwart communication between parts of the brain — and connectivity gets weaker with higher doses, according to research in rats by Marcelo Febo, a neuroscientist at the University of Florida in Gainesville. He presented the study last year at the Society for Neuroscience annual meeting (SN: 12/13/14, p. 12).

Snorting one line of bath salts can be like doing 10 lines of cocaine, Baumann says. It’s much more potent than what people are used to. High doses or repeated use of bath salts can cause excited delirium with raised body temperature, muscle breakdown and kidney failure. “People die from bath salts,” Baumann says. The biomedical literature is peppered with many more cases of deaths from bath salts than from synthetic cannabinoids.

Bath salts boost dopamine, a reward and pleasure messenger molecule, in the territory between nerve cells in the brain. This is what makes the drug so irresistible to users over time. “We know that anything that pops up dopamine to a significant degree … is going to be addictive,” says Baumann.
Bath salts swell dopamine levels by disrupting the transporter molecules that normally carry dopamine out of the space between nerve cells. Like cocaine, MDPV clogs the ports in the carrier molecule so dopamine can’t be mopped up once it has done its job, Baumann and colleagues reported in 2013 in Neuropsychopharmacology. Instead, the dopamine stays in the space between nerve cells and keeps on signaling, activating a wide array of messages within the brain.
“In this case, [MDPV] is outcompeting the dopamine,” Baumann says. The dopamine isn’t moved out of its signaling zone. “That’s the calling card of MDPV. That’s also the calling card of a very addictive substance.”

Bath salts containing two other compounds, mephedrone and methylone, take a different tack, Baumann’s group reported in 2012 in Neuropsychopharmacology. Similar in size to dopamine, these drugs can slip inside the carrier molecule, forcing it to spit dopamine into the space between neurons. In Baumann’s studies, mephedrone and methylone didn’t increase dopamine levels as much as MDPV did. But, he says, “these molecules enter cells, are accumulated inside and cause neurotoxic effects.”

Stoner behavior
There haven’t been any controlled trials of designer drugs in humans in the United States and very few in other countries. So researchers observe how the drugs alter the behavior of mice, which can help the DEA get the drugs off the street. “These models cannot prove that the drug will produce a high in humans, but they are the best we have,” says Wiley, of RTI International.

So how can she tell a mouse is stoned? Wiley injects synthetic cannabinoids into mice and looks for sluggishness, pain tolerance and lowered body temperature. Though synthetic cannabinoids have quite different chemical structures than THC (the active ingredient in marijuana), they evoke similar rodent responses. The mice sit in one spot without moving and are slow to flick their tail away when a hot light shines on it. Wiley also tests whether the mice wasted on synthetic cannabinoids act the same way they do when stoned on THC.

“The DEA needs information showing that the substances have effects similar to those of marijuana in order to work with other government agencies to ban the compounds,” Wiley says. The agency used her behavioral and chemical profiles of synthetic cannabinoids to close down a spice-selling shop in Duluth, Minn., she says.

Adam Halberstadt and Mark Geyer, psychopharmacologists at the University of California, San Diego, ran a similar battery of tests to confirm the hallucinogenic properties of NBOMes. When hallucinating, mice start quickly twitching their heads, the researchers reported last year in Neuropharmacology. Halberstadt speculates that the animals were hallucinating that they were being touched or getting wet.

The 25I-NBOMe, which sent Suzuki’s patient into a suicidal frenzy, is especially potent and also made the mice hyperactive, Halberstadt says.
NBOMes chemically resemble mescaline, a compound found in the peyote cactus. They don’t spike dopamine levels and aren’t addictive. But an overdose can prompt paranoia, seizures, a racing heart or high blood pressure. NBOMes masquerade as extra serotonin, a molecule that plays many roles in the brain, some related to mood, aggression and sensitivity to pain.

NBOMes can be dissolved and sold on paper blotters. Unfortunately, this means NBOMes are often sold as LSD. “People know that they can sell this as LSD and make more profit than they would by selling these compounds as what they really are,” says Halberstadt. “They’re being sold as something that is believed to be safe, but these don’t have the safety margin that LSD does.”

Massive doses of LSD may cause panic reactions known as bad trips, but they are unlikely to kill a person. “People know how to take LSD. It’s been around for a long time,” says Josh Elmore, a pharmacologist in Baumann’s lab. But with NBOMes, “If the person making the blotter puts a little bit too much, people die,” he says.

This lack of consistency in dosing is not limited to NBOMes. Spice is typically sprayed on plant leaves (often from the herb marshmallow) before being packaged and sold. “It’s very arbitrary and it’s up to whoever’s doing the formulation and adding the drug to that plant material,” says the DEA’s Jill Head.

This unpredictability extends to other modes of spice, which can also be vaped via e-cigarette. One of the problems is that synthetic cannabinoids dissolve poorly in the vaping liquid. The drug may start to crystallize over time, says Wiley. “If you’re down to the last little dregs of your e-liquid and it’s mostly these pieces of the chemical that have fallen out of solution, but you stuff that in your e-cigarette, what you might end up with is a very, very large dose,” she says.

A chemical Hydra
Trying to profile and ban designer drugs is like fighting Greek mythology’s many-headed Hydra, which sprouted more heads as soon as one was sliced off. The DEA can declare drugs temporarily illegal as they appear. This process, called emergency scheduling, gives the agency a chance to evaluate the drug before officially labeling it illegal. But drugmakers “can tweak substances and come up with new ones faster than the regulatory process allows us to schedule them,” says Barbara Carreno, a DEA spokesperson.

The drugs are made in China, India and Pakistan by chemical companies, Baumann says. “The people that are doing this, they’re probably Ph.D.-level chemists that are mining the medical literature for these structural templates. This isn’t the Hell’s Angels brewing stuff in a bathtub; this is a very sophisticated operation.”

Where the drugs migrate when they leave Asia can vary. “Early on in this trend of emerging synthetics, Europe was a barometer for us,” says Jeff Comparin, a forensic chemist at the DEA. When the drugs appeared in Europe, the United States would have advanced warning of about six months. “More recently, we think that we’re encountering new drugs in the United States first.”

A small kernel of self-regulation may come from within the drug-user communities — at least for NBOMes. In the last year especially there’s been a growing chorus among both users and vendors that selling NBOMes as LSD will be the new drug’s downfall, Suzuki says.

In the meantime, Baumann and his cohorts continue to profile the dizzying array of new drugs as they emerge. There’s no sign that unscrupulous chemists will stop flexing their creative muscles anytime soon. “I hope I’m wrong,” Baumann says, “but it doesn’t look like there’s any end to it. It’s essentially an infinite number of possibilities.”

This article appears in the May 16, 2015, issue with the headline, “Drugs by design: Corrupt chemists tweak compounds faster than law enforcement can call them illegal.”

How did Earth get its water?

Earth — a planet of oceans, rivers and rainforests — grew up in an interplanetary desert.

When the solar system formed about 4.6 billion years ago, shards of calcium- and aluminum-rich minerals stuck together, building ever-larger pebbles and boulders that smashed together and assembled the rocky planets, including Earth.

But Earth’s signature ingredient was nowhere to be found. Heat from the young sun vaporized any ice that dared to come near the inner planets. Earth’s relatively feeble gravity couldn’t grab on to the water vapor, or any other gas for that matter. And yet, today, Earth is a planet that runs on H2O. Water regulates the climate, shapes and reshapes the landscape and is essential to life. At birth, humans are about 78 percent water — basically a sack of the wet stuff.
To get water, Earth had to have help from somewhere else.

Researchers recently found traces of Earth’s aquatic starter kit locked away inside several meteorites, chunks of rock that fell to the planet’s surface. Those meteorites were a gift from Vesta, the second largest body in the asteroid belt between Mars and Jupiter. Vesta is thought to have formed earlier than Earth, roughly 8 million to 20 million years after the start of the solar system. (Earth needed 30 million to 100 million years to pull itself together.)

Well before the rocky planets formed, recent research suggests, ice-infused asteroids were forged beyond Jupiter and subsequently swarmed the inner solar system. These space rocks delivered water to Vesta and to Earth after being hurled at our planet by the gravity of Jupiter and Saturn. Whether the giant planets were a help or a hindrance is anybody’s guess. But if what happened here can happen anywhere, then water might be prevalent on other worlds, giving life a good chance of thriving throughout the galaxy.

Comets vs. asteroids
For decades, researchers have debated whether comets or asteroids delivered Earth’s water. At first glance, comets seemed a likely source. Originating beyond the orbit of Neptune, comets are the deep-freeze storage units of the solar system. They hold a lot of ice that has been locked away within their interiors since the formation of the solar system. Some comets are occasionally thrown inward after a close brush with a planet or passing star. It makes sense that, during the chaos of the early solar system, Earth would have been pummeled with comets, bringing plenty of water to fill the oceans.

In recent years, however, the comet hypothesis has lost favor. “It looks like comets are pretty much out,” says cosmochemist Conel Alexander of the Carnegie Institution for Science in Washington, D.C. Most of the comet water tested so far doesn’t match that of Earth’s oceans. Plus, it’s incredibly difficult to bring a comet toward Earth, much less a whole slew of them. “It just shouldn’t be part of the discussion anymore,” he says.

Part of the problem lies in a subtle chemical difference between water on Earth and water in most comets. Water is a simple molecule resembling a pair of Mickey Mouse ears: two hydrogen atoms grab a single oxygen atom. But sometimes deuterium, a slightly heavier version of hydrogen, weasels its way into the mix. The nucleus of a deuterium atom contains one proton and one neutron; in hydrogen, the proton stands alone. On Earth, only about 156 out of every 1 million water molecules contain deuterium.
Researchers have long used the relative amount of deuterium compared with hydrogen — known as the D/H ratio — to trace water back to where it originated. At colder temperatures, deuterium starts to show up in ice more frequently. So bodies that formed in the frigid backwaters of the solar system, such as comets, should be enriched in deuterium, whereas the water vapor that swirled around the infant Earth should have little to none.
Most comets appear to follow that logic; their D/H ratio is typically about twice what has been measured on Earth.

Two comets, however, threw a curveball at scientists who had counted out comets as the source of Earth’s water. In 2010, researchers used the Herschel space telescope to measure the D/H ratio of comet 103P/Hartley 2. They reported that 103P’s water nearly matched that found on Earth. Observations of comet 45P/Honda-Mrkos-Pajdušáková three years later also found abnormally low D/H ratios. Suddenly one, possibly two, comets were carrying Earthlike water.

Jupiter’s pull
Both of these comets are part of a community known as Jupiter family comets. They originated in the Kuiper belt, the ring of icy debris beyond Neptune where Pluto lives. The gravity of first Neptune and then Jupiter gradually nudged these comets into relatively short orbits that bring them closer to the sun. All previous D/H measurements were of comets that hail from the far more distant Oort cloud, a shell of ice fragments that envelops the solar system. Comets 103P and 45P suggested that researchers may have been hasty in dismissing all comets as Earth’s water source. Perhaps just the Jupiter family comets were responsible.

But then in 2014, the European Space Agency’s Rosetta probe arrived at Comet 67P/Churyumov–Gerasimenko, another Jupiter family comet. As the spacecraft sidled up to the comet, it sampled the water streaming from the comet body and found 67P’s D/H ratio to be staggeringly high — more than three times that of Earth’s oceans (SN: 1/10/15, p. 8).

“Each new comet measurement is giving us a different picture,” says Karen Meech, a planetary scientist at the University of Hawaii in Honolulu. The Rosetta results show that even among a single family of comets, there is incredible diversity in water composition. “Comets formed over a huge range of distances, so it’s no surprise that there’s a huge range in D/H,” she says.

But even if some comets have an Earth-like D/H ratio, it’s still really hard to get comets to hit our planet in the first place. “Any comet that’s going to bash into Earth has to get past this really big linebacker of Jupiter,” says planetary scientist Sean Raymond of the Laboratoire d’Astrophysique de Bordeaux in France. Jupiter has a tendency to take comets that come too close and fling them out of the solar system. The few that do end up on Earth-crossing orbits don’t stay there for long.

“The comet only has a certain number of tries to get in close and either hit Earth or get scattered on to another orbit,” Raymond says.

So Jupiter’s gravity may be too big a hurdle for comets to overcome. But it may be just the ticket for flinging asteroids at the inner planets.

A more ‘tack’-ful approach
In 2011, a team of researchers including Raymond were tackling a different problem: Why is Mars so small? There should have been plenty of raw material available 4.6 billion years ago to turn Mars into a planet closer in size to Venus or Earth. But Mars is just about half Earth’s diameter and about one-tenth its mass. One possible explanation is that something prematurely robbed the nascent Red Planet of its building blocks.

One solution, known as the Grand Tack model, describes a solar system far less sedate than the one we inhabit today (SN Online: 3/23/15). In the Grand Tack scenario, Jupiter and Saturn stride back and forth across the solar system like schoolyard bullies, hurling rocks at and stealing food from the other planets. The gas that encircled the sun dragged Jupiter and then Saturn inward. Once Jupiter arrived at about the current orbit of Mars, a gravitational tug from Saturn flung both back out from where they came (the “tack” in “Grand Tack”).  Jupiter’s encroachment on the inner solar system carved a gap in the debris field from which the rocky planets were forming, depriving Mars of raw ingredients.
Story continues below slideshow


Along with Earth, a couple of dwarf planets and several moons have shown evidence of water, in one form or another. Their potential to support life varies.
The same planetary tango that robbed Mars of resources might also explain how icy asteroids pummeled Earth. As Jupiter and Saturn wandered back out, their gravity latched on to asteroids that formed beyond the snow line — the boundary beyond which temperatures are low enough for ice to form — and flung them inward. About 1 percent of these ice-infused boulders, known as C-type asteroids, were dropped into the outer regions of the asteroid belt. But for every C-type asteroid relocated to the belt, at least 10 were sent careening into the region where the rocky planets were materializing.

This bombardment of asteroids a few million years after the start of the solar system could have easily delivered enough ice — locked inside the rocks, safe from the sun’s heat — to account for Earth’s oceans, computer simulations indicate. Water makes up to about 20 percent of the mass of some of these asteroids. On Earth, despite having more than 70 percent of its surface blanketed in blue, water accounts for only 0.023 percent of the planet’s mass. Compared with some asteroids, Earth is positively parched.

The Grand Tack nicely explains the formation of Mars, the layout of the asteroid belt and the delivery of water to Earth via icy asteroids. But Raymond stresses that it’s just one way to match all the data. “It’s an evolution of thinking,” he says. “It’s not meant to be a final solution.”

The same D/H ratio that exonerated comets is now pointing a finger at these asteroids. In 2012, Alexander and colleagues concluded in the journal Science that the bulk of Earth’s water arrived via bodies similar to a class of meteorites known as CI carbonaceous chondrites. Researchers think that these meteorites, which were knocked off asteroids that formed beyond Jupiter, are among the oldest objects in the solar system.

Alexander’s research, along with that of many others, builds a strong case for a chemical match between Earth’s water and chondrites’ water. But it doesn’t address when the water arrived. Brown University geologist Alberto Saal argues that part of the answer lies on the moon.

Story continues below graphic
The bounty of lunar samples brought to Earth by Apollo astronauts included volcanic glass hauled in during the Apollo 15 and 17 missions. The glass formed from rapidly cooling magma that was spat out from the moon’s interior long ago. In 2013, Saal and colleagues reported in Science that the D/H ratio of water trapped within the glass matched that measured in both Earth’s oceans and Alexander’s carbonaceous chondrites (SN: 6/29/13, p. 8). Saal’s findings suggest two things: Earth and the moon have a common source of water and the water was already here when the moon formed.

The moon started with a literal bang. A planet the size of Mars is thought to have smashed into Earth toward the end of our planet’s formation. The collision blasted part of Earth, as well as the unfortunate interloper, into a ring of vaporized rock that encircled Earth before sticking together to build the moon (SN: 7/12/14, p. 14). Water must have been present at the time of impact for it to be sealed into the moon, Saal notes, or it at least arrived before the moon’s surface had time to cool and solidify. This puts water near Earth about 150 million years after the start of the solar system. But based on the moon data alone, we can’t say how much earlier, says Sune Nielsen, a geologist at the Woods Hole Oceanographic Institution in Massachusetts.
To narrow in on a more precise time for water’s arrival, researchers have turned to the asteroid Vesta. Or, more specifically, meteorites nicked off Vesta after the asteroid got whacked by another space rock. Woods Hole geologist Adam Sarafian, Nielsen and colleagues analyzed small amounts of water trapped within minerals of apatite locked inside a sample of Vesta meteorites. The team reported last fall in Science that the D/H ratio of the meteorites’ water matched Earth’s. That discovery implies that whatever delivered Vesta’s water brought along Earth’s as well and that this water had to have arrived before Vesta finished forming (SN Online: 11/1/14).

That finding pushes the influx of water back, possibly as early as 8 million years after the start of the solar system. This is the oldest stockpile of water ever dated in the solar system, Nielsen says. These observations place water in the inner solar system well after Jupiter and Saturn were on the prowl, lobbing asteroids around the solar system.

Nailing down how and when water arrived at Earth is about more than just understanding how our planet was built. “If you have to have some sort of external delivery mechanism for getting water to terrestrial planets,” says Alexander, “it becomes harder to make a habitable planet.” Rocky planets forming around other stars will face the same problem that Earth faced. These planets in the habitable zones of their stars, while able to support liquid water on their surfaces, develop in dry environments and need to have ice sent in from farther out. Did Earth get lucky by having Jupiter and Saturn as neighbors, or are there other ways to move water around?

Just because Earth formed one way doesn’t mean all habitable planets must follow the same path. “I would be cautious,” Nielsen says, about saying that gas giants are the only way to bring water to rocky planets.

In fact, gas giants may even be a hindrance. “Jupiter and Saturn just screw things up,” says Raymond. Their gravity is strong enough that they tend to kick asteroids and comets right out of the solar system. If Jupiter and Saturn didn’t exist, he notes, Earth’s gravity could have stolen 10 times as much water from the outer edge of the asteroid belt. In the absence of giant planets, water delivery could happen naturally as planets pull in debris from different parts of the solar system. Recent observations from the Kepler space telescope suggest that planets the size of Jupiter are relatively uncommon around other stars. Perhaps most habitable planets do just fine on their own.

If that’s the case, then maybe the galaxy is teeming with ocean worlds waiting to be discovered. “From my point of view,” Raymond says, “having water on a planet like Earth is an everyday occurrence.”

WET AND WILD Earth may have Jupiter and Saturn to thank for sending it water way back when. The two gas giant planets did a gravitational dance with the sun and each other that sent them hurling in then back out to the outer solar system. In reaction, a bunch of icy asteroids shot into the inner solar system, pummeling early Earth and bringing it water, as shown in this animation. Credit: Drawings by Helen Thompson; Images courtesy of NASA; Narrated and produced by Helen Thompson and Ashley Yeager

This article appears in the May 16, 2015, issue with the headline, “Water, water everywhere: Every bit of Earth’s H2O was delivered by space rocks, but which ones?”

Editor’s note: This story was corrected on May 18, 2015. A caption incorrectly referred to hydrogen molecules, instead of hydrogen atoms. The Water Here and There slideshow was corrected and updated on May 20.

Wandering planets, the smell of rain and more reader feedback

Free-range planets
Astronomers are puzzling over some space oddities: planets that don’t orbit stars. In “Wandering worlds” (SN: 4/4/15, p. 22), Ashley Yeager explored how these lonely rogues may alter the definition of a planet.

Tim Geho wanted to know more about how scientists locate homeless worlds. “Where does the light come from that allows rogue planets to be seen, either directly or via gravitational lensing?” he asked. “Is there some sort of fluorescence or luminescence involved or is [light] reflected from distant suns?”
Some rogues can be imaged directly because big planets can emit their own heat, Yeager says. Telescopes detect this heat as infrared light. Identifying a planet with gravitational lensing is also possible. In this case, astronomers use light from a distant star to infer the existence of a planet. First they track the movement of the star. From the viewpoint of Earth, when the star passes behind some unseen object, the hidden object’s gravity will bend the star’s light. How much the object bends the light reveals the object’s mass. If the mass is similar to the mass of a planet, then astronomers assume that the unseen object is a planet.

Readers also had their own suggestions for what to call these rogues. Jeff Barry jokingly proposed naming them “nibirus,” after the mythical doomsday planet that is supposed to crash into Earth. John Turner commented, “Some sources refer to these nomadic bodies as ‘planemos.’ I notice we’re avoiding using that word in this article, though it’s been used in Science News pieces in the past. What gives?”
Planemo never became widely used in the astronomy community, according to Penn State astronomer Kevin Luhman . He suggests sticking with brown dwarf, while others, like Michael Liu at the University of Hawaii in Honolulu, prefer the term free-floating planet.
New thoughts on old tools
Developing new categories for types of stone tools could help anthropologists craft a more accurate view of hominid evolution, Bruce Bower reported in “Reading the stones” (SN: 4/4/15, p. 16).

Discussions on Facebook and Twitter centered on how difficult it would be to re-create some of the tools. Some readers, like Grink, declared confidently, “I can make that.” Others thought the process would be challenging. “It’s a very difficult technique,” wrote Shashank Ac. “Most modern humans would not last a day in the Stone Age.”

Mark S. took the idea a step further, suggesting a Paleolithic reenactment week: “Have the specialists get together and try to hunt, butcher and live as putative Stone Age peoples would. It would probably shed all sorts of light on what tools were really important and under what conditions. Anyone caught ordering pizza would lose their publication rights.”

The scent of rain
Andrew Grant explained how falling water drops can kick soil chemicals into the air, creating that well-known poststorm earthy aroma, in “Why rain smells like that” (SN: 4/4/15, p. 5).

The story confirmed what reader Bo Grimes had long suspected: “Ever since I first noticed the phenomenon as a child, I assumed chemicals were released from the soil, though I probably thought of it in terms of splashed dirt.” Commenter Zk10 wrote, “For whatever reason, the earthy, natural smell of raindrops on hot sand has a wonderful calming effect on me. These smells are so faint you do not even realize they are there. You just feel better. Nice to know the science behind it.”

In “An oil spill’s aftermath” (4/18/15, p. 22), U.S. District Judge Carl Barbier’s ruling about the amount of oil released in the 2010 Deepwater Horizon spill in the Gulf of Mexico was expressed incorrectly. The judge ruled that 4 million barrels of oil exited the reservoir but that, after accounting for oil collected at the site, 3.19 million barrels was discharged into the Gulf.

Cancerous clams and other sci-fi fodder

I blame my love for science fiction mostly on my mother, although my older brother Nathaniel probably should also take some of the heat. Both were voracious readers, leaving piles of books around the house, most of them sci-fi, that I couldn’t avoid escaping into.
Fans of science fiction will find a few items in this issue sure to trip the imagination. First, Tina Hesman Saey describes a discovery akin to something out of Alien: roving cancer cells that move from victim to victim, sneaking into others’ bodies to produce more of themselves. Saey, a lover of science fiction herself, calls it “cancer as parasite” or — as one researcher put it — extreme out-of-body metastasis.
Of course, this contagious cancer attacks clams, not people. But biologically, it’s pretty far-out. The leukemia-like disease is not, as was initially thought, caused by a virus. Jumping genes — bits of DNA that move around a chromosome, embedding themselves in places that can trigger cancers — may play some role. These genes revealed that clams from Maine to Maryland have the exact same malignancy — and that the cancer cells are genetically distinct from the clams’ own cells.

It’s the third example of contagious cancer in the animal world, but it’s the only one with no apparent direct contact between the carriers. What if there are other, similar types of cancers that we don’t know about? “That’s scarier to me than any virus,” says Saey. And good fodder for a thriller.

Also seemingly out of the pages of a novel: new drugs of abuse, designed by chemists to mimic illicit drugs but to evade legal restrictions, with some scary effects, as science writing intern Kate Baggaley describes. Or, see Christopher Crockett’s report about the effort to trace the origin of Earth’s water, which apparently was imported from some extraterrestrial source.

For a taste of actual sci-fi, see my brief review of the movie Ex Machina. It’s no Star Wars, but it does what some of the best science fiction does: uses futuristic technology to explore bigger, broader issues involving humans and society. It also offers a bit of an escape.

Ivory listings found on Craigslist as elephant poaching continues

Many of the world’s largest herbivores are threatened with extinction, scientists reported last week in Science Advances. Some of them, such as giraffes and zebras, are at risk because they are hunted for their meat. But elephants, which also make the threatened list, are prized not for their flesh but for their two large ivory tusks. For millennia, people have used ivory for everything from piano keys to false teeth to figurines. And despite plastic having long ago replaced ivory for commonplace items like buttons, trade in ivory has tripled since 1998 largely due to rising demand in Asia.

That trade thrives in some unlikely places. The International Fund for Animal Welfare, for instance, recently found hundreds of pieces of ivory worth millions of dollars being advertised on Craigslist within the United States — despite the site’s policy of prohibiting trade in animal parts. Craigslist responded to the report by adding ivory to its list of prohibited items, but IFAW notes that the list is pretty easy to ignore. IFAW recommends making those rules more visible and automatically alerting Craigslist staff when someone lists ivory or other elephant products on the site. But who knows how effective that will be. (And another recommendation to implement search filtering that would prevent people from searching for the term “ivory” is probably a non-starter — people selling ivory-colored products, such as wedding dresses, are sure to object.)
After IFAW discovered ivory objects for sale on eBay and Etsy, those companies began working with law enforcement to reduce the wildlife trade on those sites. And IFAW would like Craigslist to follow suit.

But the United States isn’t really the big problem — it’s Asia, and particularly China. Not only is ivory incredibly popular there, but there’s actually a subset of wealthy people who are stocking up on products made from elephants and other endangered species as investments, banking on extinction to make those products more valuable in the near future.

I was pleased to see last year that former NBA star Yao Ming has taken up the elephant cause and now campaigns against the ivory trade in China. His previous work with the group WildAid led to a decline in popularity of shark fin soup and a reduction in shark fin sales. Hopefully he will be as influential with ivory because as long as ivory is in demand, people will be willing to kill elephants so they can take home a tidy profit.

For the African elephant, there may be yet another problem: There is no “African elephant.” There are actually two species of African elephant, forest (Loxodonta cyclotis) and savannah (L. africana), and many conservation groups don’t differentiate, Alfred Roca of the University of Illinois at Urbana-Champaign and colleagues noted in the February Annual Reviews Animal Biosciences. Grouping all the African elephants together and assuming that all the populations are interchangeable puts both species at risk, the researchers warn. “It’s like saying, ‘We increased the lion population, which will more than make up for the fact that tigers are going extinct,’” Roca said in a statement.

Will there be any elephants left when I am old and gray? With the rate at which poachers are killing the animals for their ivory — 100,000 were killed in just three years — and inadequate plans for saving the creatures, I worry that the answer to my question increasingly looks like “no.”

Possible nearest living relatives to complex life found in seafloor mud

Cold mud from the seafloor has revealed signs of a new group of microbes that could be the nearest living relatives yet found to the domain of life that includes people and other creatures with fancy cell structures.

That mud carries DNA of a previously unknown and unusual phylum of one-celled microbes, researchers report online May 6 in Nature.

The microbes in this newly named Lokiarchaeota phylum carry the basic DNA of one-celled life called archaea, sisters to the domain of bacteria. Yet they possess roughly 100 genes that resemble those in eukaryotes, organisms with intricate structures in their cells.
“What was very surprising was the type of function of these genes,” says paper coauthor Thijs Ettema of Uppsala University in Sweden. What the genes do in Lokiarchaeota is still a matter of hypothesis. But in eukaryotes, many of these genes help with tasks not observed in archaea, such as changing cell shape and controlling internal compartments called vesicles.
The discovery of Lokiarchaeota could intensify debates about how living cells got complex. In recent decades, biologists largely embraced a broad view that divided living organisms into three vast domains: Two — archaea and bacteria — have single cells with no nuclei holding DNA or little structures tucked into membranes.

The third domain — eukaryotes — packages DNA inside cell nuclei and furnishes cells with internal nuggets such as mitochondria that specialize in handling energy. How such elaborate cells arose has puzzled biologists since they have not found clear-cut intermediate forms that suggest the evolutionary steps.

The new find has “genes that might provide a very good starting point to becoming eukaryote,” says James McInerney of the National University of Ireland Maynooth. It strengthens a hypothesis, called the ring of life, that eukaryotes arose not from a single ancient lineage but rather by mingling genes from two kinds of less-structured cells.

This hypothesis is especially promising in light of the discovery of Lokiarchaeota genes that might allow these organisms’ cell membranes to engulf other cells, says evolutionary biologist Mary O’Connell of Dublin City University. One objection to the ring-of-life idea has been the need to explain how genetic merging took place when neither archaea nor bacteria appear able to swallow other organisms. The new phylum, however, might have managed.

It took extreme feats of computing to discover the new genetic mix, Ettema says. Researchers extracted DNA from promising bits of mud in a sediment core coaxed from the ocean floor more than two kilometers deep along the Arctic Mid-Ocean Ridge. The researchers censused the DNA fragments with a computer program that sorted bits into separate kinds of life.

The Lokiarchaeota showed up as a blend of genes, some distinctive to archaea and others resembling those from eukaryotes. The more eukaryote-like genes aren’t likely to be genetic material snitched from full-fledged eukaryotes, Ettema says. Microbes do snitch, but these genes were scattered among bona fide archaea DNA instead of appearing in chunks, as stolen goods do. And though similar, they were not entirely like eukaryote genes.

Since these conclusions are based on computer analysis of DNA, “we have huge gaps in our knowledge of what these beasts actually are,” McInerney says. “There is a lot of work to do to try to really understand if their relatives 2 billion years ago were important for formation of the eukaryotic cell.”

The top side of an elephant’s trunk stretches more than the bottom

On a sunny day at Zoo Atlanta in 2020, Kelly the African bush elephant reached for a snack and revealed something strange.

High-speed cameras tracking her movements suggested that the skin on top of Kelly’s trunk stretched more than the skin underneath. “But that didn’t make any sense,” says Andrew Schulz, a mechanical engineer at Georgia Tech in Atlanta.

Scientists had assumed that elephant trunk skin largely stretches the same way all over. When Schulz sent data from Kelly and a male elephant, Msholo, to colleagues, they said, “Oh yeah, your data is wrong,” he remembers.
Follow-up experiments stretching pieces of elephant skin in the lab showed the same peculiar phenomenon: The skin on the top and bottom of the trunk are two entirely different beasts. “Talk about a great day as a scientist!” Schulz says. “That’s when we really started to believe that what we were saying was true.”

The tough upper skin of an elephant’s trunk, which crumples into creases and crags like the folded furrows of a shar-pei puppy, is about 15 percent stretchier than the gently wrinkled skin on the underside, Schulz and his colleagues report July 18 in the Proceedings of the National Academy of Sciences.
That extra stretch probably helps elephants reach down and wrap their trunks around a log or a tree branch, while the wrinkled skin underneath gives the animals a good grip, Schulz says.

The team also observed that the trunk extends like a telescope, the tip reaching out first, followed by sections farther up. And at the trunk tip, it’s the skin that does most of the straining, not the muscle, mathematical modeling experiments suggest.

Scientists have long studied the muscles in elephant trunks (SN: 3/26/88). But skin has largely been overlooked, says Lucia Beccai, a soft roboticist at the Italian Institute of Technology in Genoa who wasn’t involved in the research. The new study “tells us that the structure of elephant skin is not all the same.”

Artificial skin is often modeled after human skin, but researchers could learn a lot from other animals, Beccai says. Understanding how Kelly’s and Msholo’s folds and wrinkles stretch is “surely information that will improve the design of soft robots,” she says.

Here are experts’ answers to questions about COVID-19 vaccines for little kids

Four weeks ago, the U.S. Centers for Disease Control and Prevention signed off on COVID-19 vaccines for young children. Days later, doctors’ offices and clinics began rolling out shots for babies and toddlers.

In Portland, Ore., a clinic featuring bubbles, toys and a dance party delivered more than 1,100 shots in two days. In Arizona, more than 2,000 kids under 5 have received their first dose in about three weeks. Over the same time period in Fayetteville, Ga., one practice has given out roughly 100 doses to young kids.
As of July 14, nearly 400,000 kids under 5 have received at least one dose, the CDC reports. That’s about 2 percent of eligible children in this age group.

Pediatrician Eliza Hayes Bakken has seen an initial rush of parents who signed up for appointments as soon as the vaccines became available. “There’s a huge push of families that want to be in that first group that’s vaccinated,” says Bakken, who treats kids at Oregon Health & Sciences University Doernbecher Children’s Hospital in Portland. She suspects demand will soon taper off, following a pattern pediatricians have seen with vaccinations in older age groups.

Getting young kids vaccinated may be a long, slow haul, says Adrianne Hammershaimb, a pediatric infectious disease specialist at the University of Maryland School of Medicine in Baltimore. About half of U.S. parents with children under 4 said they were likely to get their kids the shot, her team reported last month in the Journal of the Pediatric and Infectious Diseases Society. That number is “lower than we’d like, but it’s not surprising,” she says.

Only about 55 percent of U.S. adults surveyed say COVID-19 vaccination has been extremely or very effective at limiting the coronavirus’ spread, the Pew Research Center in Washington, D.C., reported on July 7. In Hammershaimb’s experience, the issue isn’t that most parents are anti-vaxxers or mistrust all vaccines. Rather, “parents are genuinely concerned about the unknown,” she says. There’s a lot of misinformation out there, she notes, and people are trying to figure out what’s best for their kids.

As BA.5 continues to spark cases (now accounting for some 65 percent of new infections in the United States), parents are talking to doctors about COVID-19 risks, vaccine safety and vaccination timing. Here, Hammershaimb and three other pediatricians answer some common questions they’ve been getting.

Is COVID-19 really a problem for kids?
“This is one big question we get a lot,” Hammershaimb says. Kids are just as likely to catch COVID-19 as adults, though cases tend to be milder. Half of kids infected may have no symptoms at all.

The disease also tends to be deadlier for adults than children. In people ages 55 and older, COVID-19 is the third leading cause of death in the United States, scientists reported July 5 in JAMA Internal Medicine. But COVID-19 can hit kids hard, too. It ranks as the eighth leading cause of death in people 19 and under in the United States.
“You hear on TV that COVID is not a big deal for kids,” says Sara Goza, a pediatrician in Fayetteville, Ga., who served as president of the American Academy of Pediatrics in 2020. “That’s a little bit shocking.” In her practice, she’s seen infected children develop long COVID and chronic fatigue. “This disease is not without its complications,” she says.

Bakken’s 9-year-old son caught COVID-19 in 2020, before the vaccine came out. His case wasn’t particularly serious, but he did have long-term effects. He had to take more medication to control his asthma and be extra cautious playing sports. That may seem minor, Bakken says, but it didn’t feel that way for her son. “It affected his daily life.”

What are the side effects of COVID-19 vaccines?
Parents taking their young kids to get the shot can expect to see side effects similar to those common in other childhood vaccines. Fatigue, fussiness, redness at the injection site ​​— those are signs the body is responding to the vaccine like it’s supposed to, Bakken says. Some kids may have no side effects, and that’s OK, too, she says.

Vaccine safety is another topic parents have questioned (something that also came up in a recent Science News Twitter poll). Clinical trials and real-world data suggest the vaccines are safe for kids and adults, Bakken says. “Adverse events are exceedingly rare — much more rare than complications from COVID itself.”
Take myocarditis, the rare heart inflammation condition sometimes seen after getting Pfizer’s or Moderna’s mRNA COVID-19 vaccines. In boys between the ages of 12 and 17, myocarditis crops up in roughly 1 out of 10,000 following vaccination, scientists reported July 13 in the BMJ.

But teen boys are up to six times more likely to experience heart complications after COVID-19 infection compared with after vaccination, CDC scientists reported in April. In younger boys, ages 5 to 11, heart complications following vaccination are even more rare. And in most people with myocarditis following vaccination, symptoms improve quickly and the heart fully recovers.

Hammershaimb is keeping an eye on CDC and U.S. Food and Drug Administration monitoring systems that track potential adverse events to the vaccine. If anything concerning comes up, she says, ”we can intervene, halt the vaccination program, and take a close look at any cases that are reported.” Ultimately, she says, parents need to weigh the hypothetical risk of a rare adverse reaction against the known risks of COVID-19 infection.

Should parents wait until the fall to vaccinate their kids?
No, Hammershaimb says. She encourages parents to sign their kids up for their shots this summer, so they’ll head into fall with some coronavirus protection already built up. It’s possible that COVID-19 boosters targeting the omicron variant may be available as the school year kicks off, but that doesn’t mean parents should wait, she says. “We want kids to be as protected as they can be when they go back to the classroom.”

Sophie Katz, a pediatric infectious disease doctor in Nashville, agrees. Though the current vaccines’ ability to prevent omicron infection in kids seems to wane rapidly, the shots continue to be effective against hospitalization, she wrote in a JAMA editorial in May. And a study of kids in Israel who had received the Pfizer vaccine found that two doses offered moderate protection against the original omicron variant, scientists reported in the New England Journal of Medicine on June 29.

Katz’s 13-month-old baby has already had COVID-19, but she says, “I am 100 percent going to get her vaccinated.” For Katz, it’s a matter of protecting her child from severe disease. “I will do anything to keep my daughter out of the hospital.”