Flying forward is hard enough, but flying nowhere, just hovering, is so much harder. Most bats and birds can manage the feat for only a few frantic seconds.
Hovering means losing a useful aerodynamic shortcut, says aerospace engineer and biologist David Lentink of Stanford University. As a bat or bird flies forward, its body movement sends air flowing around the wings and providing some cheap lift. For animals on the scale of bats and birds, that’s a big help. Without that boost, “you’re going to have to move all the air over your wings by moving it with your wings,” he says. The energy per second you’re consuming to stay in place by flapping your wings back and forth like a hummingbird “is gigantic.” So how do vertebrates in search of nectar, for whom a lot of energy-sucking hovering is part of life, manage the job? For the first direct measurements of the wingbeat forces that make hovering possible, Lentink’s Ph.D. student Rivers Ingersoll spent three years creating a flight chamber with exquisitely responsive sensors in the floor and ceiling. As a bird or bat hovers inside, the sensors can measure — every 200th of a second — tremors even smaller than a nanometer caused by air from fluttering wings. Once the delicate techno-marvel of an instrument was perfected, the researchers packed it into 11 shipping cases and sent it more than 6,000 kilometers to the wilds of Costa Rica. “Very difficult,” Ingersoll acknowledges. The Las Cruces Research Station is great for field biology, but it’s nothing like a Stanford engineering lab. Every car turning into the station’s driveway set off the wingbeat sensors. And even the special thick-walled room that became the machine’s second home warmed up enough every day to give the instrument a fever. Babying the instrument as best he could, Ingersoll made direct measurements for 17 hovering species of hummingbirds and three bats, including Pallas’s long-tongued bats (Glossophaga soricina). “Their up-pointy noses made me think of rhino faces,” he says. Pallas’s bats specialize in nectar sipping much as hummingbirds do. Comparing wingbeats, bat vs. bird, revealed differences, though. Hummers coupled powerful downstrokes and recovery upstrokes that twist part of the wings almost backward. The twist supplied about a quarter of the energy it takes to keep a bird aloft, the researchers report in the September 26 Science Advances. The two kinds of nectar bats got a little more lift from the upstroke than did a bat that eats fruit instead of strenuously hovering for nectar. Yet even the specialist nectar bats relied mostly on downstrokes: powerful, deeply angled downstrokes of really big wings.
Those bat wings span proportionally more area than hummer wings. So the bats get about the same hovering power per gram of body weight that hummingbirds do. Supersizing can have its own kind of high-tech design elegance.
Ross D.E. MacPhee and Peter Schouten (illustrator) W.W. Norton & Co., $35
Today’s land animals are a bunch of runts compared with creatures from the not-too-distant past. Beasts as big as elephants, gorillas and bears were once much more common around the world. Then, seemingly suddenly, hundreds of big species, including the woolly mammoth, the giant ground sloth and a lizard weighing as much as half a ton, disappeared. In End of the Megafauna, paleomammalogist Ross MacPhee makes one thing clear: The science on what caused the extinctions of these megafauna — animals larger than 44 kilograms, or about 100 pounds — is far from settled. MacPhee dissects the evidence behind two main ideas: that as humans moved into new parts of the world over the last 50,000 years, people hunted the critters into oblivion, or that changes in climate left the animals too vulnerable to survive. As MacPhee shows, neither scenario matches all of the available data.
Throughout, Peter Schouten’s illustrations, reminiscent of paintings that enliven natural history museums, bring the behemoths back to life. At times, MacPhee slips in too many technical terms. But overall, he offers readers an informative, up-to-date overview of a fascinating period in Earth’s history.
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The cabbage tree emperor moth has wings with tiny scales that absorb sound waves sent out by bats searching for food. That absorption reduces the echoes that bounce back to bats, allowing Bunaea alcinoe to avoid being so noticeable to the nocturnal predators, researchers report online November 12 in the Proceedings of the National Academy of Sciences.
“They have this stealth coating on their body surfaces which absorbs the sound,” says study coauthor Marc Holderied, a bioacoustician at the University of Bristol in England. “We now understand the mechanism behind it.”
Bats sense their surroundings using echolocation, sending out sound waves that bounce off objects and return as echoes picked up by the bats’ supersensitive ears (SN: 9/30/17, p. 22). These moths, without ears that might alert them to an approaching predator, have instead developed scales of a size, shape and thickness suited to absorbing ultrasonic sound frequencies used by bats, the researchers found. The team shot ultrasonic sound waves at a single, microscopic scale and observed it transferring sound wave energy into movement. The scientists then simulated the process with a 3-D computer model that showed the scale absorbing up to 50 percent of the energy from sound waves.
What’s more, it isn’t just wings that help such earless moths evade bats. Other moths in the same family as B. alcinoe also have sound-absorbing fur, the same researchers report online October 18 in the Journal of the Acoustical Society of America. Holderied and his colleagues studied the fluffy thoraxes of the Madagascan bullseye moth and the promethea silk moth, and found that the fur also absorbs sound waves through a different process called porous absorption. In lab tests, the furry-bellied moths absorbed as much as 85 percent of the sound waves encountered. Researchers suspect that the equally fluffy cabbage tree emperor moth also has this ability.
Other moths that have ears can hear bats coming, and can quickly swerve out of the way of their predators, dipping and diving in dizzying directions (SN: 5/26/18, p. 11). Some moths also have long tails on their wings that researchers suspect can be twirled to disrupt bats’ sound waves (SN: 3/21/15, p. 17). Still other moths produce toxins to fend off foes.
Having sound-absorbent fur and scales “might require a lot less energy in terms of protection from the moth’s side,” says Akito Kawahara, an evolutionary biologist at the Florida Museum of Natural History in Gainesville who was not involved with the study. “It’s a very different kind of passive defense system.”
Holderied and his colleagues hope next to study how multiple scales, locked together, respond to ultrasonic sound waves. The findings could one day help in developing better soundproofing technology for sound engineers and acousticians.
Screwworms, the first pest to be eliminated on a large scale by the use of the sterile male technique, have shown an alarming increase, according to U.S. and Mexican officials…. The screwworm fly lays its eggs in open wounds on cattle. The maggots live on the flesh of their host, causing damage and death, and economic losses of many millions of dollars. — Science News, November 23, 1968
Update Though eradicated in the United States in 1966, screwworms reemerged two years later, probably coming up from Mexico. Outbreaks in southern U.S. states in 1972 and in Florida in 2016 were both handled with the sterile male technique, considered one of the most successful approaches for pest control. Males are sterilized with radiation, then released into a population to breed with wild counterparts; no offspring result. The method has been used with other pests, such as mosquitoes, which were dropped by drones over Brazil this year as a test before the technology is used against outbreaks like the Zika virus.
Off a gravel road at the edge of a college campus — next door to the town’s holding pen for stray dogs — is a busy test site for the newest technologies in drinking water treatment.
In the large shed-turned-laboratory, University of Massachusetts Amherst engineer David Reckhow has started a movement. More people want to use his lab to test new water treatment technologies than the building has space for.
The lab is a revitalization success story. In the 1970s, when the Clean Water Act put new restrictions on water pollution, the diminutive grey building in Amherst, Mass. was a place to test those pollution-control measures. But funding was fickle, and over the years, the building fell into disrepair. In 2015, Reckhow brought the site back to life. He and a team of researchers cleaned out the junk, whacked the weeds that engulfed the building and installed hundreds of thousands of dollars worth of monitoring equipment, much of it donated or bought secondhand.
“We recognized that there’s a lot of need for drinking water technology,” Reckhow says. Researchers, students and start-up companies all want access to test ways to disinfect drinking water, filter out contaminants or detect water-quality slipups. On a Monday afternoon in October, the lab is busy. Students crunch data around a big table in the main room. Small-scale tests of technology that uses electrochemistry to clean water chug along, hooked up to monitors that track water quality. On a lab bench sits a graduate student’s low-cost replica of an expensive piece of monitoring equipment. The device alerts water treatment plants when the by-products of disinfection chemicals in a water supply are reaching dangerous levels. In an attached garage, two startup companies are running larger-scale tests of new kinds of membranes that filter out contaminants. Parked behind the shed is the almost-ready-to-roll newcomer. Starting in 2019, the Mobile Water Innovation Laboratory will take promising new and affordable technologies to local communities for testing. That’s important, says Reckhow, because there’s so much variety in the quality of water that comes into drinking water treatment plants. On-site testing is the only way to know whether a new approach is effective, he says, especially for newer technologies without long-term track records.
The facility’s popularity reflects a persistent concern in the United States: how to ensure affordable access to clean, safe drinking water. Although U.S. drinking water is heavily regulated and pretty clean overall, recent high-profile contamination cases, such as the 2014 lead crisis in Flint, Mich. (SN: 3/19/16, p. 8), have exposed weaknesses in the system and shaken people’s trust in their tap water. Tapped out In 2013 and 2014, 42 drinking water–associated outbreaks resulted in more than 1,000 illnesses and 13 deaths, based on reports to the U.S. Centers for Disease Control and Prevention. The top culprits were Legionella bacteria and some form of chemical, toxin or parasite, according to data published in November 2017.
Those numbers tell only part of the story, however. Many of the contaminants that the U.S. Environmental Protection Agency regulates through the 1974 Safe Drinking Water Act cause problems only when exposure happens over time; the effects of contaminants like lead don’t appear immediately after exposure. Records of EPA rule violations note that in 2015, 21 million people were served by drinking water systems that didn’t meet standards, researchers reported in a February study in the Proceedings of the National Academy of Sciences. That report tracked trends in drinking water violations from 1982 to 2015. Current technology can remove most contaminants, says David Sedlak, an environmental engineer at the University of California, Berkeley. Those include microbes, arsenic, nitrates and lead. “And then there are some that are very difficult to degrade or transform,” such as industrial chemicals called PFAS.
Smaller communities, especially, can’t always afford top-of-the-line equipment or infrastructure overhauls to, for example, replace lead pipes. So Reckhow’s facility is testing approaches to help communities address water-quality issues in affordable ways. Some researchers are adding technologies to deal with new, potentially harmful contaminants. Others are designing approaches that work with existing water infrastructure or clean up contaminants at their source.
How is your water treated? A typical drinking water treatment plant sends water through a series of steps.
First, coagulants are added to the water. These chemicals clump together sediments, which can cloud water or make it taste funny, so they are bigger and easier to remove. A gentle shaking or spinning of the water, called flocculation, helps those clumps form (1). Next, the water flows into big tanks to sit for a while so the sediments can fall to the bottom (2). The cleaner water then moves through membranes that filter out smaller contaminants (3). Disinfection, via chemicals or ultraviolet light, kills harmful bacteria and viruses (4). Then the water is ready for distribution (5). There’s a lot of room for variation within that basic water treatment process. Chemicals added at different stages can trigger reactions that break down chunky, toxic organic molecules into less harmful bits. Ion-exchange systems that separate contaminants by their electric charge can remove ions like magnesium or calcium that make water “hard,” as well as heavy metals, such as lead and arsenic, and nitrates from fertilizer runoff. Cities mix and match these strategies, adjusting chemicals and prioritizing treatment components, based on the precise chemical qualities of the local water supply.
Some water utilities are streamlining the treatment process by installing technologies like reverse osmosis, which removes nearly everything from the water by forcing the water molecules through a selectively permeable membrane with extremely tiny holes. Reverse osmosis can replace a number of steps in the water treatment process or reduce the number of chemicals added to water. But it’s expensive to install and operate, keeping it out of reach for many cities.
Fourteen percent of U.S. residents get water from wells and other private sources that aren’t regulated by the Safe Drinking Water Act. These people face the same contamination challenges as municipal water systems, but without the regulatory oversight, community support or funding.
“When it comes to lead in private wells … you’re on your own. Nobody is going to help you,” says Marc Edwards, the Virginia Tech engineer who helped uncover the Flint water crisis. Edwards and Virginia Tech colleague Kelsey Pieper collected water-quality data from over 2,000 wells across Virginia in 2012 and 2013. Some were fine, but others had lead levels of more than 100 parts per billion. When levels are higher than its 15 ppb threshold, the EPA mandates that cities take steps to control corrosion and notify the public about the contamination. The researchers reported those findings in 2015 in the Journal of Water and Health.
To remove lead and other contaminants, well users often rely on point-of-use treatments. A filter on the tap removes most, but not all, contaminants. Some people spring for costly reverse osmosis systems. New tech solutions These three new water-cleaning approaches wouldn’t require costly infrastructure overhauls.
Ferrate to cover many bases Reckhow’s team at UMass Amherst is testing ferrate, an ion of iron, as a replacement for several water treatment steps. First, ferrate kills bacteria in the water. Next, it breaks down carbon-based chemical contaminants into smaller, less harmful molecules. Finally, it makes ions like manganese less soluble in water so they are easier to filter out, Reckhow and colleagues reported in 2016 in Journal–American Water Association. With its multifaceted effects, ferrate could potentially streamline the drinking water treatment process or reduce the use of chemicals, such as chlorine, that can yield dangerous by-products, says Joseph Goodwill, an environmental engineer at the University of Rhode Island in Kingston.
Ferrate could be a useful disinfectant for smaller drinking water systems that don’t have the infrastructure, expertise or money to implement something like ozone treatment, an approach that uses ozone gas to break down contaminants, Reckhow says.
Early next year, in the maiden voyage of his mobile water treatment lab, Reckhow plans to test the ferrate approach in the small Massachusetts town of Gloucester. In the 36-foot trailer is a squeaky-clean array of plastic pipes and holding tanks. The setup routes incoming water through the same series of steps — purifying, filtering and disinfecting — that one would find in a standard drinking water treatment plant. With two sets of everything, scientists can run side-by-side experiments, comparing a new technology’s performance against the standard approach. That way researchers can see whether a new technology works better than existing options, says Patrick Wittbold, the UMass Amherst research engineer who headed up the trailer’s design.
Charged membranes Filtering membranes tend to get clogged with small particles. “That’s been the Achilles’ heel of membrane treatment,” says Brian Chaplin, an engineer at the University of Illinois at Chicago. Unclogging the filter wastes energy and increases costs. Electricity might solve that problem and offer some side benefits, Chaplin suggests.
His team tested an electrochemical membrane made of titanium oxide or titanium dioxide that both filters water and acts as an electrode. Chemical reactions happening on the electrically charged membranes can turn nitrates into nitrogen gas or split water molecules, generating reactive ions that can oxidize contaminants in the water. The reactions also prevent particles from sticking to the membrane. Large carbon-based molecules like benzene become smaller and less harmful. In lab tests, the membranes effectively filtered and destroyed contaminants, Chaplin says. In one test, a membrane transformed 67 percent of the nitrates in a solution into other molecules. The finished water was below the EPA’s regulatory nitrate limit of 10 parts per million, he and colleagues reported in July in Environmental Science and Technology. Chaplin expects to move the membrane into pilot tests within the next two years.
Obliterate the PFAS The industrial chemicals known as PFAS present two challenges. Only the larger ones are effectively removed by granular activated carbon, the active material in many household water filters. The smaller PFAS remain in the water, says Christopher Higgins, an environmental engineer at the Colorado School of Mines in Golden. Plus, filtering isn’t enough because the chunky chemicals are hard to break down for safe disposal.
Higgins and colleague Timothy Strathmann, also at the Colorado School of Mines, are working on a process to destroy PFAS. First, a specialized filter with tiny holes grabs the molecules out of the water. Then, sulfite is added to the concentrated mixture of contaminants. When hit with ultraviolet light, the sulfite generates reactive electrons that break down the tough carbon-fluorine bonds in the PFAS molecules. Within 30 minutes, the combination of UV radiation and sulfites almost completely destroyed one type of PFAS, other researchers reported in 2016 in Environmental Science and Technology.
Soon, Higgins and Strathmann will test the process at Peterson Air Force Base in Colorado, one of nearly 200 U.S. sites known to have groundwater contaminated by PFAS. Cleaning up those sites would remove the pollutants from groundwater that may also feed wells or city water systems.
As the asteroid Bennu comes into sharper focus, planetary scientists are seeing signs of water locked up in the asteroid’s rocks, NASA team members announced December 10.
“It’s one of the things we were hoping to find,” team member Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Md., said in a news conference at the American Geophysical Union meeting in Washington, D.C. “This is evidence of liquid water in Bennu’s past. This is really big news.” NASA’s OSIRIS-REx spacecraft just arrived at Bennu on December 3 (SN Online: 12/3/18). Over the next year, the team will search for the perfect spot on the asteroid to grab a handful of dust and return it to Earth. “Very early in the mission, we’ve found out Bennu is going to provide the type of material we want to return,” said principal investigator Dante Lauretta of the University of Arizona in Tucson. “It definitely looks like we’ve gone to the right place.”
OSIRIS-REx’s onboard spectrometers measure the chemical signatures of various minerals based on the wavelengths of light they emit and absorb. The instruments were able to see signs of hydrated minerals on Bennu’s surface about a month before the spacecraft arrived at the asteroid, and the signal has remained strong all over the asteroid’s surface as the spacecraft approached, Simon said. Those minerals can form only in the presence of liquid water, and suggest that Bennu had a hydrothermal system in its past.
Bennu’s surface is also covered in more boulders and craters than the team had expected based on observations of the asteroid taken from Earth. Remote observations led the team to expect a few large boulders, about 10 meters wide. Instead they see hundreds, some of them up to 50 meters wide.
“It’s a little more rugged of an environment,” Lauretta said. But that rough surface can reveal details of Bennu’s internal structure and history. If Bennu were one solid mass, for instance, a major impact could crack or shatter its entire surface. The fact that it has large craters means it has survived impacts intact. It may be more of a rubble pile loosely held together by its own gravity. The asteroid’s density supports the rubble pile idea. OSIRIS-REx’s first estimate of Bennu’s density shows it is about 1,200 kilograms per cubic meter, Lauretta said. The average rock is about 3,000 kilograms per cubic meter. The hydrated minerals go some way towards lowering the asteroid’s density, since water is less dense than rock. But up to 40 percent of the asteroid may be full of caves and voids as well, Lauretta said.
Some of the rocks on the surface appear to be fractured in a spindly pattern. “If you drop a dinner plate on the ground, you get a spider web of fractures,” says team member Kevin Walsh of the Southwest Research Institute in Boulder, Colo. “We’re seeing this in some boulders.”
The boulders may have cracked in response to the drastic change in temperatures they experience as the asteroid spins. Studying those fracture patterns in more detail will reveal the properties of the rocks.
The OSIRIS-REx team also needs to know how many boulders of various sizes are strewn across the asteroid’s surface. Any rock larger than about 20 centimeters across would pose a hazard to the spacecraft’s sampling arm, says Keara Burke of the University of Arizona. Burke, an undergraduate engineering student, is heading up a boulder mapping project. “My primary goal is safety,” she says. “If it looks like a boulder to me, within reasonable guidelines, then I mark it as a boulder. We can’t sample anything if we’re going to crash.”
The team also needs to know where the smallest grains of rock and dust are, as OSIRIS-REx’s sampling arm can pick up grains only about 2 centimeters across. One way to find the small rocks is to measure how well the asteroid’s surface retains heat. Bigger rocks are slower to heat up and slower to cool down, so they’ll radiate heat out into space even on the asteroid’s night side. Smaller grains of dust heat up and cool down much more quickly.
“It’s exactly like a beach,” Walsh says. “During the day it’s scalding hot, but then it’s instantly cold when the sun sets.”
Measurements of the asteroid’s heat storage so far suggest that there are regions with grains as small as 1 or 2 centimeters across, Lauretta said, though it is still too early to be certain.
“I am confident that we’ll find some fine-grained regions,” Lauretta said. Some may be located inside craters. The challenge will be finding an area wide enough that the spacecraft’s navigation system can steer to it accurately.
WASHINGTON – A months-long heat wave that scorched the Tasman Sea beginning in November of 2017 is the latest example of an extreme event that would not have happened without human-caused climate change.
Climate change also increased the likelihood of 15 other extreme weather events in 2017, from droughts in East Africa and the U.S. northern Plains states to floods in Bangladesh, China and South America, scientists reported December 10 at a news conference at the American Geophysical Union’s fall meeting. The findings were also published online December 10 in a series of studies in a special issue of the Bulletin of the American Meteorological Society. One study, of wildfires in Australia, was inconclusive on whether climate change influenced the event. And for the first time, none of the extreme events studied was determined to be the product of natural climate variability.
The findings mark the second year in a row — and only the second time — that scientists contributing to this special issue have definitively linked human-caused climate change with specific extreme weather events (SN: 1/20/18, p. 6). To the editors of the special issue, this latest tally is representative of the new normal in which the world finds itself.
“Many events were found to have appreciable climate change input; that’s not itself a surprise,” said Martin Hoerling, a special editor of the issue, at the news conference. “We are in a world that is warmer than it was in the 20th century, and we keep moving away from that baseline….”
“Nature is unfolding itself in front of our eyes,” added Hoerling, a research meteorologist with the U.S. National Oceanic and Atmospheric Administration in Boulder, Colo. Marine heat waves Several marine heat waves have struck the Tasman Sea, located between Australia and New Zealand, in the last decade, including a severe heat wave during the Southern Hemisphere summer of 2015 to 2016. But the 2017–2018 event extended across a much broader area, encompassing the entire sea. At its most severe point, temperatures increased to at least 2 degrees Celsius above average in the ocean, devastating the region’s iconic kelp forests and contributing to record-breaking summer temperatures in New Zealand.
Climate change was also responsible for another marine heat wave off the coast of East Africa that lasted from March to June 2017, according to a separate study. That marine heat wave, which the researchers found could not have happened in a preindustrial climate, also may have contributed to a drought in East Africa that caused food shortages for millions of people in the Horn of Africa, including 6 million in Somalia alone. The hot sea surface temperatures, the researchers found, doubled the probability that such a drought would occur.
“Any given extreme event might occur, but the severity of the events, that’s really what has changed. And it’s going to continue to change,” says Karsten Haustein, a climate scientist at the University of Oxford who is part of a research group that specializes in such climate attribution studies. Haustein is a coauthor on a study included in the collection that found that climate change dramatically increased the likelihood — by as much as 100 percent — of a six-day rainstorm that inundated Bangladesh in March 2017. The rainfall, which caused a flash flood, occurred before the onset of the monsoon season and proved devastating to farmers, Haustein says.
Legal liability The new issue highlights how the field of climate attribution science overall has crossed a critical threshold when it comes to liability, Lindene Patton, a strategic advisor at the Earth & Water Law Group in Washington, D.C., who specializes in climate attribution, said at the news conference. Although climate change was not found to be definitively to blame in most of the studies, it very likely was responsible for or intensified the impacts of nearly every extreme event examined in the issue — and that level of statistical certainty is enough to be legally important, Patton said. “The sufficiency of certainty differs in a court of law and in science. Perfection is not required; you just need to know if it’s more likely than not.”
The threat of liability may not be the ideal way to achieve more environment-friendly policies — but there is a precedent for it, she noted. “We clearly saw the emergence of liability in the 1970s with pollution” as a precursor to pollutant legislation.
BAMS Editor in Chief Jeff Rosenfeld acknowledges that in a world where real-time attribution studies of events such as 2018’s Hurricane Florence are becoming more common (SN Online: 9/13/18), the detailed, retrospective analyses of the BAMS special issue that lag by a year may seem a bit slow. “The funny thing is, initially, we considered it fast response,” he says.
But he thinks the looming question of climate liability highlights why the slower, more deliberate BAMS studies will continue to remain relevant, even in the swiftly changing climate of attribution science. “The people who are decision makers want numbers. They want risk factors.”
The results are in: Ultima Thule, the distant Kuiper Belt object that got a close visit from the New Horizons spacecraft on New Year’s Day, looks like two balls stuck together.
“What you are seeing is the first contact binary ever explored by a spacecraft, two separate objects that are now joined together,” principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colo., said January 2 in a news conference held at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
“It’s a snowman, if it’s anything at all,” Stern said. (Twitter was quick to supply another analogy: the rolling BB-8 droid from Star Wars.)
That shape is enough to lend credence to the idea that planetary bodies grow up by the slow clumping of small rocks. Ultima Thule, whose official name is 2014 MU69, is thought to be among the oldest and least-altered objects in the solar system, so knowing how it formed can reveal how planets formed in general (SN Online: 12/18/18). “Think of New Horizons as a time machine … that has brought us back to the very beginning of solar system history, to a place where we can observe the most primordial building blocks of the planets,” said Jeff Moore of NASA’s Ames Research Center in Moffett Field, Calif., who leads New Horizons’ geology team. “It’s gratifying to see these perfectly formed contact binaries in their native habitat. Our ideas of how these things form seem to be somewhat vindicated by these observations.”
The view from about 28,000 kilometers away shows that MU69 is about 33 kilometers long and has two spherical lobes, one about three times the size of the other. The spheres are connected by a narrow “neck” that appears brighter than much of the rest of the surface. That could be explained by small grains of surface material rolling downhill to settle in the neck, because small grains tend to reflect more light than large ones, said New Horizons deputy project scientist Cathy Olkin of the Southwest Research Institute. Even the brightest areas reflected only about 13 percent of the sunlight that hit them, though. The darkest reflected just 6 percent, about the same brightness as potting soil.
Measurements also show that MU69 rotates once every 15 hours, give or take one hour. That’s a Goldilocks rotation speed, Olkin said. If it spun too fast, MU69 would break apart; too slow would be hard to explain for such a small body. Fifteen hours is just right.
The lobes’ spherical shape is best explained by collections of small rocks glomming together to form larger rocks, Moore said. The collisions between the rocks happened at extremely slow speeds, so the rocks accreted rather than breaking each other apart. The final collision was between the two spheres, which the team dubbed “Ultima” (the bigger one) and “Thule” (the smaller one). That collision probably happened at no more than a few kilometers per hour, “the speed at which you might park your car in a parking space,” Moore said. “If you had a collision with another car at those speeds, you may not even bother to fill out the insurance forms.”
New Horizons also picked up MU69’s reddish color. The science team thinks the rusty hue comes from radiation altering exotic ice, frozen material like methane or nitrogen rather than water, although they don’t know exactly what that ice is made of yet.
The spacecraft is still sending data back to Earth, and will continue transmitting details of the flyby for the next 18 months. Even as the New Horizons team members shared the first pictures from the spacecraft’s flyby, data was arriving that will reveal details of MU69’s surface composition.
“The real excitement today is going to be in the composition team room,” Olkin said. “There’s no way to make anything like this type of observation without having a spacecraft there.”
There’s no sorrier sight than a puking preschooler. That’s the conclusion I recently reached around 2 a.m. as my poor 4-year-old heaved into the dim abyss. Luckily, her bout with the stomach flu was brief, and she was feeling better by the next day.
Stomach flu, also known as gastroenteritis, is a common affliction caused by bacteria or viruses that inflame the gut. Though mercifully short, the misery this brings is complete, for both the sufferer and the person charged with scrubbing chunks out of sheets, carpet and a stuffed toy cupcake. So when presented with something that could potentially cut short the puking, any parent would jump at the chance. That’s the promise of probiotics, “good” bacteria (typically in pill form) that some people think might help restore the irritated gut and get kids feeling better faster. But according to two big studies (here and here) of puking kids and probiotics, parents should save their money for something else.
For both studies, scientists studied kids ages 3 months to 4 years who came to an emergency department with acute gastroenteritis. In addition to receiving regular care, these kids took either a probiotic or placebo for five days. Then the researchers tallied up the kids’ symptoms to see if those who got the live bugs fared better than those who received a placebo. Long story short, the scientists found absolutely no differences.
The trials used different bacteria as probiotics. One used Lactobacillus rhamnosus, sold as products such as Culturelle, and the other used that bacteria plus Lactobacillus helveticus, a combination sold as Lacidofil. Neither of the formulations cut puking or other symptoms short. The kids had about the same duration of diarrhea (about two days) and missed the same amount of daycare (two days on average).
As far as studies go, these results, both published November 22 in the New England Journal of Medicine, are pretty clear: Probiotics didn’t help puking kids feel better faster. Of course, it’s possible that certain types of probiotics are good for other things, as an editorial in the same issue of the NEJM points out. Scientists have been studying whether probiotics can curb colic in babies, with some hints that helpful bacteria may reduce crying in breastfed babies (though the jury is still out). Other bacteria might also help newborns at risk of developing dangerous infections, as a recent study on babies in rural India suggests.
But when it comes to gastroenteritis in kids, probiotics’ benefits don’t seem to be there. If you’re desperate and willing to throw money at the problem, go ahead and buy your poor puking kid some probiotics. There’s no evidence they hurt, and it might make you feel like you’re doing something. Still, you’re probably better off spending your money on juice and popsicles.
Data from NASA’s now-defunct Cassini spacecraft show that five odd-shaped moons embedded in Saturn’s rings are different colors, and that the hues come from the rings themselves, researchers report. That observation could help scientists figure out how the moons were born.
“The ring moons and the rings themselves are kind of one and the same,” says planetary scientist Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “For as long as the moons have existed, they’ve been accreting particles from the rings.” Saturn has more than 60 moons, but those nearest to the planet interact closely with its main band of rings. Between December 2016 and April 2017, Cassini passed close to five of these ring-dwelling moons: ravioli-shaped Pan and Atlas (SN Online: 3/10/17), ring-sculpting Daphnis and Pandora (SN: 9/2/17, p. 16) and potato-shaped Epimetheus. The flybys brought Cassini between two and 10 times closer to the moons than it had ever been, before the spacecraft deliberately crashed into Saturn in September 2017 (SN Online: 9/15/17).
Examining those close-ups, Buratti and her colleagues noticed that the moons’ colors vary depending on the objects’ distances from Saturn. And the moon hues are similar to the colors of the rings that the objects are closest to, the team reports online March 28 in Science. Close-in Pan was the reddest moon, while the farthest-out Epimetheus was the bluest. The researchers think the red material comes from Saturn’s dense main rings, and mostly consists of organics and iron (SN Online: 10/4/18). The blue material is probably water ice from Saturn’s more distant E ring, which is created by plumes erupting from the larger, icy moon Enceladus. The team thinks that the rings are continually depositing material onto the moons. “It’s an ongoing process,” Buratti says. She notes that “skirts” of material at Atlas and Pan’s equators are probably made of accreted ring debris, too.
The overall similarity between the moons and rings led the researchers to conclude that these small moons are leftover shards of a destructive event that created the rings in the first place. But it’s unknown whether that event was a collision between long-gone, larger moons, the shredding of one moon by Saturn’s gravity, or some other occurrence (SN: 1/20/18, p. 7).
Saturn, its rings and its moons are “very dynamic,” says planetary scientist Matija Ćuk of the SETI Institute in Mountain View, Calif. The idea that the rings are still shedding material onto the moons today “sounds perfectly reasonable.” He isn’t sure the moons formed at the same time as the rings, though. It’s possible “they formed from the rings since that catastrophic event,” he says.
