In Sierra Leone, a woman sleeps with her baby under a mosquito net to keep malaria-infected mosquitoes away. A new study finds that a monoclonal antibody holds promise for protecting young children from malaria for months.
A single shot that could provide months-long protection against malaria has proven effective and safe in a small, early clinical trial of adults.
The shot, which contains monoclonal antibodies, would primarily be intended for infants and children in countries with the most malaria transmission, the team who conducted the trial says. These young children have the highest risk of dying from severe malaria.
In the clinical trial, 15 of 17 participants who received the monoclonal antibodies did not become infected after being exposed to mosquitoes with malaria in the lab, the researchers report in the Aug. 4 New England Journal of Medicine . All six people who did not receive the medicine developed infections.
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The clinical trial tested different doses and delivered the medicine intravenously or as a shot. Based on a computer model of how the medicine is taken up, distributed and then cleared by the body, the researchers estimate that one shot may protect against malaria for six months.
“What we’ve always been looking for is some sort of intervention that will prevent infection reliably and for as long a time as possible,” says Miriam Laufer, a pediatric infectious disease doctor and director of the Malaria Research Program at the University of Maryland School of Medicine in Baltimore.
Ideally, Laufer says, that would be a highly effective vaccine that provides years and years of protection. A new malaria vaccine has recently become available, but it is only modestly protective against the disease, and that protection wanes rapidly ( SN: 12/22/21 ). The vaccine requires four shots.
Monoclonal antibodies could provide an option that requires only one shot, once a year. It will take more research to see how well the antibodies work against malaria outside of the laboratory and how cost-effective the shot is.
The monoclonal antibodies shot wouldn’t exclude the need for other prevention strategies, says Laufer, who was not involved in the new study. But it could be “one of the easier interventions in terms of minimal contact with the health care system, with good benefit.”
What’s appealing, she says, “is the possibility that you could give kids, even the youngest kids, an injection [of] premade antibodies that could last for six months or longer and protect them throughout the rainy season.” That once-a-season shot would be helpful in countries in West Africa, where malaria transmission only occurs during the rainy season.
Malaria sickened an estimated 241 million people and killed 627,000 worldwide in 2020. Most of those deaths occurred in sub-Saharan Africa in children younger than 5. These littlest kids haven’t had the chance to develop immunity to the disease and are more susceptible to dying if severe malaria develops.
Reducing the spread of malaria includes measures to control mosquitoes, such as using insecticide-treated nets over beds or spraying to kill mosquitoes indoors, as well as preventing infections, such as taking antimalarial drugs at regular intervals. In October 2021, the World Health Organization also recommended the new vaccine, which in clinical trials reduced cases of malaria and severe malaria by 36 percent after four years of follow-up.
Monoclonal antibodies are a laboratory-made version of antibodies, the proteins that the immune system produces in response to a vaccine or natural infection. Monoclonal means that it contains clones, or copies, of one particular antibody.
The antibody evaluated in the clinical trial attaches to a protein on the surface of sporozoites — the form of the malaria parasite that enters the body after an infected mosquito bites — and stops the parasites from infecting the liver.
The new monoclonal antibody has improvements over an earlier version developed by the same research team. The new version binds more strongly to the targeted malaria parasite protein. It also has a tweak that keeps it from degrading too quickly in the body. This boosts its half-life in the blood (the time it takes for half of the medicine to degrade) to 56 days, almost three times that of its predecessor.
Two clinical trials are planned to assess how well the medicine protects children in places where malaria is spreading. One trial in Mali, where malaria transmission is seasonal, will study the shot’s efficacy over seven months. Another trial in Kenya, among the countries in East Africa where malaria spreads year-round, will assess how well the shot works while following the children for a year. Those studies will also help to determine the best dose for children.
Aimee Cunningham is the biomedical writer. She has a master’s degree in science journalism from New York University.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.
Scientists have literally reanimated dead spiders to do their bidding.
In a new field dubbed “necrobotics,” researchers converted the corpses of wolf spiders into grippers that can manipulate objects. All the team had to do was stab a syringe into a dead spider’s back and superglue it in place. Pushing fluid in and out of the cadaver made its legs clench open and shut, the researchers report July 25 in Advanced Science .
The idea was born from a simple question, explains Faye Yap, a mechanical engineer at Rice University in Houston. Why do spiders curl up when they die?
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The answer: Spiders are hydraulic machines ( SN: 4/25/22 ). They control how much their legs extend by forcing blood into them. A dead spider no longer has that blood pressure, so its legs curl up.
“We were just thinking that was so cool,” Yap says. “We wanted to leverage it.”
Her team first tried putting dead wolf spiders in a double boiler, hoping that the wet heat would make the spiders expand and push their legs outward. That didn’t work. But when the researchers injected fluid straight into a spider corpse, they found that they could control its grip well enough to pull wires from a circuit board and pick up other dead spiders. Only after hundreds of uses did the necrobots start to become dehydrated and show signs of wear.
In the future, the researchers will coat spiders with a sealant to hold off that decline. But the next big step is to control the spiders’ legs individually, Yap says, and in the process, figure out more about how spiders work. Then her team could translate their understanding into better designs for other robots.
“That would be very, very interesting,” says Rashid Bashir, a bioengineer at the University of Illinois Urbana-Champaign who wasn’t involved in the new study. A spider corpse itself would probably have problems as a robot, he says, because it won’t perform consistently like “hard robots” and its body will break down over time. But spiders can definitely offer lessons to engineers ( SN: 4/2/19 ). “There’s a lot to be learned from biology and nature,” Bashir says.
Despite the whole reanimating dead spiders thing, Yap is no mad scientist. She wonders whether it’s okay to play Frankenstein, even with spiders. “No one really talks about the ethics” when it comes to this sort of research, she says.
Scientists need to figure out the morality of this sort of bioengineering before they get too good at it, Bashir agrees. The question is, he says, “how far do you go?”
Asa Stahl is the 2022 AAAS Mass Media fellow with Science News . He is a 5th year Astrophysics Ph.D. student at Rice University, where his research focuses on detecting and characterizing young stars and planets.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.
The proposed Windchime dark matter detector would work a bit like a backyard wind chime. Instead of rods swinging in a breeze, billions of sensors would be nudged by the gravity of a dark matter breeze blowing past Earth.
The secret to directly detecting dark matter might be blowin’ in the wind.
The mysterious substance continues to elude scientists even though it outweighs visible matter in the universe by about 8 to 1. All laboratory attempts to directly detect dark matter — seen only indirectly by the effect its gravity has on the motions of stars and galaxies — have gone unfulfilled.
Those attempts have relied on the hope that dark matter has at least some other interaction with ordinary matter in addition to gravity ( SN: 10/25/16 ). But a proposed experiment called Windchime, though decades from being realized, will try something new: It will search for dark matter using the only force it is guaranteed to feel — gravity.
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“The core idea is extremely simple,” says theoretical physicist Daniel Carney, who described the scheme in May at a meeting of the American Physical Society’s Division of Atomic Molecular and Optical Physics in Orlando, Fla. Like a wind chime on a porch rattling in a breeze, the Windchime detector would try to sense a dark matter “wind ” blowing past Earth as the solar system whips around the galaxy.
If the Milky Way is mostly a cloud of dark matter, as astronomical measurements suggest, then we should be sailing through it at about 200 kilometers per second. This creates a dark matter wind, for the same reason you feel a wind when you stick your hand out the window of a moving car.
The Windchime detector is based on the notion that a collection of pendulums will swing in a breeze. In the case of backyard wind chimes, it might be metal rods or dangling bells that jingle in moving air. For the dark matter detector, the pendulums are arrays of minute, ultrasensitive detectors that will be jostled by the gravitational forces they feel from passing bits of dark matter. Instead of air molecules bouncing off metal chimes, the gravitational attraction of the particles that make up the dark matter wind would cause distinctive ripples as it blows through a billion or so sensors in a box measuring about a meter per side.
While it may seem logical to search for dark matter using gravity, no one has tried it in the nearly 40 years that scientists have been pursuing dark matter in the lab. That’s because gravity is, comparatively, a very weak force and difficult to isolate in experiments.
“You’re looking for dark matter to [cause] a gravitational signal in the sensor,” says Carney, of Lawrence Berkeley National Laboratory in California. “And you just ask . . . could I possibly see this gravitational signal? When you first make the estimate, the answer is no. It’s actually going to be infeasibly difficult.”
That didn’t stop Carney and a small group of colleagues from exploring the idea anyway in 2020 . “Thirty years ago, this would have been totally nuts to propose,” he says. “It’s still kind of nuts, but it’s like borderline insanity.”
The Windchime Project collaboration has since grown to include 20 physicists. They have a prototype Windchime built of commercial accelerometers and are using it to develop the software and analysis that will lead to the final version of the detector, but it’s a far cry from the ultimate design. Carney estimates that it could take another few decades to develop sensors good enough to measure gravity even from heavy dark matter.
Carney bases the timeline on the development of the Laser Interferometer Gravitational-Wave Interferometer , or LIGO, which was designed to look for gravitational ripples coming from black holes colliding ( SN: 2/11/16 ). When LIGO was first conceived, he says, it was clear that the technology would need to be improved by a hundred million times. Decades of development resulted in an observatory that views the sky in gravitational waves. With Windchime, “we’re in the exact same boat,” he says.
Even in its final form, Windchime will be sensitive only to dark matter bits that are roughly the mass of a fine speck of dust. That’s enormous on the spectrum of known particles — more than a million trillion times the mass of a proton.
“There is a variety of very interesting dark matter candidates at [that scale] that are definitely worth looking for … including primordial black holes from the early universe,” says Katherine Freese, a physicist at the University of Michigan in Ann Arbor who is not part of the Windchime collaboration. Black holes slowly evaporate, leaking mass back into space, she notes, which could leave many relics formed shortly after the Big Bang at the mass Windchime could detect.
But if it never detects anything at all, the experiment still stands out from other dark matter detection schemes, says Dan Hooper, a physicist at Fermilab in Batavia, Ill., also not affiliated with the project. That’s because it would be the first experiment that could entirely rule out some types of dark matter.
Even if the experiment turns up nothing, Hooper says, “the amazing thing about [Windchime] … is that, independent of anything else you know about dark matter particles, they aren’t in this mass range.” With existing experiments , a failure to detect anything could instead be due to flawed guesses about the forces that affect dark matter ( SN: 7/7/22 ).
Windchime will be the only experiment yet imagined where seeing nothing would definitively tell researchers what dark matter isn’t. With a little luck, though, it could uncover a wind of tiny black holes, or even more exotic dark matter bits, blowing past as we careen around the Milky Way.
James Riordon is a freelance science writer who covers physics, math, astronomy and occasional lifestyle stories.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.
Few things are harder than hurling a robot into space — and sticking the landing. On the morning of July 4, 1997, mission controllers at the Jet Propulsion Laboratory in Pasadena, Calif., were hoping to beat the odds and land a spacecraft successfully on the Red Planet.
Twenty-five years ago that little robot, a six-wheeled rover named Sojourner, made it — becoming the first in a string of rovers built and operated by NASA to explore Mars. Four more NASA rovers, each more capable and complex than the last, have surveyed the Red Planet. The one named Curiosity marked its 10th year of cruising around on August 5. Another, named Perseverance, is busy collecting rocks that future robots are supposed to retrieve and bring back to Earth. China recently got into the Mars exploring game, landing its own rover, Zhurong, last year.
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Other Mars spacecraft have done amazing science from a standstill, such as the twin Viking landers in the 1970s that were the first to photograph the Martian surface up close and the InSight probe that has been listening for Marsquakes shaking the planet’s innards ( SN Online: 2/24/20 ). But the ability to rove turns a robot into an interplanetary field geologist, able to explore the landscape and piece together clues to its history. Mobility, says Kirsten Siebach, a planetary scientist at Rice University in Houston, “makes it a journey of discovery.”
Five U.S. rovers and one Chinese rover have reached Mars, all visiting different locations on the planet. Many focused on areas that may have once been wet and favorable for potential life.
Each of the Mars rovers has gone to a different place on the planet, enabling scientists to build a broad understanding of how Mars evolved over time. The rovers revealed that Mars contained water, and other life-friendly conditions, for much of its history. That work set the stage for Perseverance’s ongoing hunt for signs of ancient life on Mars.
The ruggedness of the rovers is a big factor in how far they travel and how long they operate. Three of the machines are still exploring.
Each rover is also a reflection of the humans who designed and built and drove it. Perseverance carries on one of its wheels a symbol of Mars rover tracks twisted into the double helix shape of DNA. That’s “to remind us, whatever this rover is, it’s of human origin,” says Jennifer Trosper, an engineer at the Jet Propulsion Lab, or JPL, who has worked on all five NASA rovers. “It is us on Mars, and kind of our creation.”
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Sojourner, that first rover, was born in an era when engineers weren’t sure if they even could get a robot to work on Mars. In the early 1990s, then-NASA Administrator Daniel Goldin was pushing the agency to do things “faster, better and cheaper” — a catchphrase that engineers would mock by saying only two of those three things were possible at the same time. NASA had no experience with interplanetary rovers. Only the Soviet Union had operated rovers — on the moon in 1970 and 1973.
JPL began developing a Mars rover anyway. Named after the abolitionist Sojourner Truth, the basic machine was the size of a microwave oven. Engineers were limited in where they could send it; they needed a large flat region on Mars because handling a precision landing near mountains or canyons was beyond their abilities. NASA chose Ares Vallis, a broad outflow channel from an ancient flood, and the mission landed there successfully.
Sojourner spent nearly three months poking around the landscape. It was slow going. Mission controllers had to communicate with Sojourner constantly, telling it where to roll and then assessing whether it had gotten there safely. They made mistakes: One time they uploaded a sequence of computer commands that mistakenly told the rover to shut itself down. They recovered from that stumble and many others, learning to quickly fix problems and move forward.
Although Sojourner was a test mission to show that a rover could work, it managed to do some science with its one X-ray spectrometer. The little machine analyzed the chemical makeup of 15 Martian rocks and tested the friction of the Martian soil.
After surviving 11 weeks beyond its planned one-week lifetime, Sojourner ultimately grew too cold to operate. Trosper was in mission control when the rover died on September 27, 1997. “You build these things, and even if they’re well beyond their lifetime, you just can’t let go very easily, because they’re part of you,” she says.
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In 1998 and 1999, NASA hurled a pair of spacecraft at Mars; one was supposed to orbit the planet and another was supposed to land near one of the poles. Both failed. Stung from the disappointment, NASA decided to build a rover plus a backup for its next attempt.
Thus were born the twins Spirit and Opportunity. Each the size of a golf cart, they were a major step up from Sojourner. Each had a robotic arm, a crucial development in rover evolution that enabled the machines to do increasingly sophisticated science. The two had beefed-up cameras, three spectrometers and a tool that could grind into rocks to reveal the texture beneath the surface.
But there were a lot of bugs to work out. Spirit and Opportunity launched several weeks apart in 2003. Spirit got to Mars first, and on its 18th Martian day on the surface it froze up and started sending error messages. It took mission controllers days to sort out the problem — an overloaded flash-memory system — all while Opportunity was barreling toward Mars. Ultimately, engineers fixed the problem, and Opportunity landed safely on the opposite side of the planet from Spirit.
Both rovers lasted years beyond their expected three-month lifetimes. And both did far more Martian science than anticipated.
Spirit broke one of its wheels early on and had to drive backward, dragging the broken wheel behind it. But the rover found plenty to do near its landing site of Gusev crater, home to a classic Mars landscape of dust, rock and hills. Spirit found rocks that appeared to have been altered by water long ago and later spotted a pair of iron-rich meteorites. The rover ultimately perished in 2010, stuck in a sand-filled pit. Mission controllers tried to extract it in an effort dubbed “Free Spirit,” but salts had precipitated around the sand grains, making them particularly slippery.
Opportunity, in contrast, became the Energizer Bunny of rovers, exploring constantly and refusing to die. Immediately after landing in Meridiani Planum, Opportunity had scientists abuzz.
“The images that the rover first sent back were just so different from any other images we’d seen of the Martian surface,” says Abigail Fraeman, a planetary scientist at JPL. “Instead of these really dusty volcanic plains, there was just this dark sand and this really bright bedrock. And that was just so captivating and inspiring.”
Right at its landing site, Opportunity spotted the first definitive evidence of past liquid water on Mars , a much-anticipated and huge discovery ( SN: 3/27/04, p. 195 ). The rover went on to find evidence of liquid water at different times in the Martian past. After years of driving, the rover reached a crater called Endeavour and “stepped into a totally new world,” Fraeman says. The rocks at Endeavour were hundreds of millions of years older than others studied on Mars. They contained evidence of different types of ancient water chemistry.
Opportunity ultimately drove farther than any rover on any extraterrestrial world, breaking a Soviet rover’s lunar record. In 2015, Opportunity passed 26.2 miles (42.2 km) on its odometer; mission controllers celebrated by putting a marathon medal onto a mock-up of the rover and driving it through a finish line ribbon at JPL. Opportunity finally died in 2019 after an intense dust storm obscured the sun, cutting off solar power, a must-have for the rover to recharge its batteries ( SN: 3/16/19, p. 7 ).
The twin rovers were a huge advance over Sojourner. But the next rover was an entirely different beast.
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By the mid-2000s, NASA had decided it needed to go big on Mars, with a megarover the size of a sports utility vehicle. The one-ton Curiosity was so heavy that its engineers had to come up with an entirely new way to land on Mars. The “sky crane” system used retro-rockets to hover above the Martian surface and slowly lower the rover to the ground.
Against all odds, in August 2012, Curiosity landed safely near Mount Sharp , a 5-kilometer-high pile of sediment within the 154-kilometer-wide Gale crater ( SN: 8/25/12, p. 5 ). Unlike the first three Mars rovers, which were solar-powered, Curiosity runs on energy produced by the radioactive decay of plutonium. That allows the rover to travel farther and faster, and to power a suite of sophisticated science instruments, including two chemical laboratories.
Curiosity introduced a new way of exploring Mars. When the rover arrives in a new area, it looks around with its cameras, then zaps interesting rocks with its laser to identify which ones are worth a closer look. Once up close, the rover stretches out its robotic arm and does science, including drilling into rocks to see what they are made of.
When Curiosity arrived near the base of Mount Sharp, it immediately spotted rounded pebbles shaped by a once-flowing river, the first closeup look at an ancient river on Mars. Then mission controllers sent the rover rolling away from the mountain, toward an area in the crater known as Yellowknife Bay. There Curiosity discovered evidence of an ancient lake that created life-friendly conditions for potentially many thousands of years.
Curiosity then headed back toward the foothills of Mount Sharp. Along the way, the rover discovered a range of organic molecules in many different rocks, hinting at environments that had been habitable for millions to tens of millions of years. It sniffed methane gas sporadically wafting within Gale crater , a still-unexplained mystery that could result from geologic reactions, though methane on Earth can be formed by living organisms ( SN: 7/7/18, p. 8 ). The rover measured radiation levels across the surface — helpful for future astronauts who’ll need to gauge their exposure — and observed dust devils, clouds and eclipses in the Martian atmosphere and night sky.
“We’ve encountered so many unexpectedly rich things,” says Ashwin Vasavada of JPL, the mission’s project scientist. “I’m just glad a place like this existed.”
Ten years into its mission, Curiosity still trundles on, making new discoveries as it climbs the foothills of Mount Sharp. It recently departed a clay-rich environment and is now entering one that is heavier in sulfates, a transition that may reflect a major shift in the Martian climate billions of years ago.
In the course of driving more than 28 kilometers, Curiosity has weathered major glitches, including one that shuttered its drilling system for over a year. And its wheels have been banged up more than earthbound tests had predicted. The rover will continue to roll until some unknown failure kills it or its plutonium power wanes, perhaps five years from now.
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NASA’s first four rovers set the stage for the most capable and agile rover ever to visit Mars: Perseverance. Trosper likens the evolution of the machines to the growth of children. “We have a preschooler in Sojourner, and then … your happy-go-lucky teenagers in Spirit and Opportunity,” she says. “Curiosity is certainly a young adult that’s able to do a lot of things on her own, and Perseverance is kind of that high-powered midcareer [person] able to do pretty much anything you ask with really no questions.”
Perseverance is basically a copy of Curiosity built from its spare parts, but with one major modification: a system for drilling, collecting and storing slender cores of rock. Perseverance’s job is to collect samples of Martian rock for future missions to bring to Earth, in what would be the first robotic sample return from Mars. That would allow scientists to do sophisticated analyses of Martian rocks in their earthbound labs. “It feels, even more than previous missions, that we are doing this for the next generation,” Siebach says.
The rover is working fast. Compared with Curiosity’s leisurely exploration of Gale crater, Perseverance has been zooming around its landing site, the 45-kilometer-wide Jezero crater, since its February 2021 arrival. It has collected 10 rock cores and is already eyeing where to put them down on the surface for future missions to pick up. “We’re going to bring samples back from a diversity of locations,” says mission project scientist Kenneth Farley of Caltech. “And so we keep to a schedule.”
Perseverance went to Jezero to study an ancient river delta, which contains layers of sediment that may harbor evidence of ancient Martian life. But the rover slightly missed its target, landing on the other side of a set of impassable sand dunes. So it spent most of its first year exploring the crater floor , which turned out to be made of igneous rocks ( SN: 9/11/21, p. 32 ). The rocks had cooled from molten magma and were not the sedimentary rocks that many had expected.
Scientists back on Earth will be able to precisely date the age of the igneous rocks, based on the radioactive decay of chemical elements within them, providing the first direct evidence for the age of rocks from a particular place on Mars.
Once it finished exploring the crater floor in March, the rover drove quickly toward the delta. Each successive NASA rover has had greater skills in autonomous driving, able to identify hazards, steer around them and keep going without needing constant instructions from mission control.
Perseverance has a separate computer processor to run calculations for autonomous navigation, allowing it to move faster than Curiosity. (It took Curiosity two and a half years to travel 10 kilometers; Perseverance traveled that far in a little over a year.) “The rover drives pretty much every minute that we can give it,” Farley says.
In April, Perseverance set a Martian driving record, traveling nearly five kilometers in just 30 Martian days. If all goes well, it will make some trips up and down the delta, then travel to Jezero crater’s rim and out onto the ancient plains beyond.
Perseverance has a sidekick, Ingenuity, the first helicopter to visit another world. The nimble flier, only half a meter tall, succeeded beyond its designers’ wildest dreams. The helicopter made 29 flights in its first 16 months when it was only supposed to make five in one month. It has scouted paths ahead and scientific targets for the rover ( SN Online: 4/19/22 ). Future rovers are almost certain to carry a little buddy like this.
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While the United States has led in Mars rover exploration, it is not the only player on the scene. In May 2021, China became the second nation to successfully place a rover on Mars. Its Zhurong rover, named after a mythological fire god, has been exploring part of a large basin in the planet’s northern hemisphere known as Utopia Planitia.
The landing site lies near a geologic boundary that may be an ancient Martian shoreline. Compared with the other Mars rover locations, Zhurong’s landing site is billions of years younger, “so we are investigating a different world on Mars,” says Lu Pan, a planetary scientist at the University of Copenhagen who has collaborated with Zhurong scientists.
In many ways, Zhurong resembles Spirit and Opportunity, in size as well as mobility. It carries cameras, a laser spectrometer for studying rocks and ground-penetrating radar to probe underground soil structures ( SN Online: 5/19/21 ).
After landing, Zhurong snapped pictures of its rock-strewn surroundings and headed south to explore a variety of geologic terrains, including mysterious cones that could be mud volcanoes and ridges that look like windblown dunes. The rover’s initial findings include that the Martian soil at Utopia Planitia is similar to some desert sands on Earth and that water had been present there perhaps as recently as 700 million years ago.
In May, mission controllers switched Zhurong into dormant mode for the Martian winter and hope it wakes up at the end of the season, in December. It has already traveled nearly two kilometers across the surface, farther than the meager 100 meters that Sojourner managed. (To be fair, Sojourner had to keep circling its lander because it relied on that lander to communicate with Earth.)
From Sojourner to Zhurong, the Mars rovers show what humankind can accomplish on another planet. Future rovers might include the European Space Agency’s ExoMars, although its 2022 launch was postponed after Russia attacked Ukraine ( SN: 3/26/22, p. 6 ). Europe terminated all research collaborations with Russia after the invasion, including launching ExoMars on a Russian rocket.
Vasavada remembers his sense of awe at the Curiosity launch in 2011: “Standing there in Florida, watching this rocket blasting off and feeling it in your chest and knowing that there’s this incredibly fragile complex machine hurtling on the end of this rocket.… It just gave me this full impression that here we are, humans, blasting these things off into space,” he says. “We’re little tiny human beings sending these things to another planet.”
Alexandra Witze is a contributing correspondent for Science News . Based in Boulder, Colo., Witze specializes in earth, planetary and astronomical sciences.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.
Starlight can erode the atmospheres of some mini-Neptune exoplanets (one illustrated), gradually turning them into super-Earths, rocky worlds a bit bigger than our own.
Mini-Neptunes and super-Earths may have a lot more in common than just being superlatives.
Four gaseous exoplanets, each a bit smaller than Neptune, seem to be evolving into super-Earths, rocky worlds up to 1.5 times the width of our home planet. That’s because the intense radiation of their stars appears to be pushing away the planets’ thick atmospheres , researchers report in a paper submitted July 26 at arXiv.org. If the current rate of atmospheric loss keeps up, the team predicts, those puffy atmospheres will eventually vanish, leaving behind smaller planets of bare rock.
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Studying how these worlds evolve and lose their atmospheres can help scientists understand how other exoplanets lose their atmospheres. And that, says astronomer Heather Knutson of Caltech, can provide intel on what types of planets might have habitable environments. “Because if you can’t keep an atmosphere,” she says, “you can’t be habitable.”
Knutson and her colleagues’ new study bolsters a previous suspicion. Earlier this year, the same researchers reported that helium seemed to be escaping the atmosphere of one these mini-Neptunes. But the team wasn’t sure if their discovery was a one-off. “Maybe we just got very lucky for this one planet, but every other planet is different,” says exoplanet researcher Michael Zhang, also of Caltech.
So the team looked at three more mini-Neptunes orbiting other stars and compared those worlds to the first planet they had observed. Each of these planets occasionally blocks some of the light from its star ( SN: 7/21/21 ). Zhang, Knutson and colleagues tracked how long each planet blocked its stars’ light and how much of that starlight was absorbed by helium enveloping the planets. Together, these observations let the team measure the sizes and shapes of the planets’ atmospheres.
“When a planet is losing its atmosphere, you get this big, sort of cometlike tail of gas coming out from the planet,” Knutson says. If the gas instead is still bound to the planet — as is the case for Neptune in our solar system — the astronomers would have seen a circle. “We don’t fully understand all the shapes that we see in the outflows,” she says, “but we see they’re not spherical.”
In other words, each planet is steadily losing its helium. “I never would have guessed that every single planet we looked at, that we would see such a clear detection,” Knutson says.
The astronomers also calculated how much mass those exoplanets were losing ( SN: 6/19/17 ). “This mass loss rate is high enough to strip the atmospheres of at least most of these planets, so that some of them, at least, will become super-Earths,” Zhang says.
These rates, though, are just snapshots in time, says Ian Crossfield, an exoplanet researcher at the University of Kansas in Lawrence who was not involved with this work. For each planet, “you don’t know exactly how it’s been losing atmosphere throughout its entire history and into the future,” he says. “All we know is what we see today.” Even with such open questions, he adds, the idea that mini-Neptunes turn into super-Earths “seems plausible.”
Theories and computer simulations of how planets form and lose their atmospheres can help fill in some of the blanks on individual planets, Crossfield says.
Measurements of more mini-Neptunes will also help. Zhang plans to observe another handful. In addition, “we’ve already looked at one more target, and that target also has a pretty strong escaping helium [signal],” he says. “Now we have five for five.”
Liz Kruesi has written about astronomy and space since 2005, and received the AAS High-Energy Astrophysics Division science journalism award in 2013. She holds a bachelor’s degree in physics from Lawrence University in Appleton, Wisc.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.
Light from the cosmic microwave background (right, illustrated in orange and blue) passed by distant galaxies (purple) on its way to Earth. The gravity of those galaxies bent that light (white lines), revealing their distribution of dark matter.
Scientists have mapped out the dark matter around some of the earliest, most distant galaxies yet.
The 1.5 million galaxies appear as they were 12 billion years ago, or less than 2 billion years after the Big Bang. Those galaxies distort the cosmic microwave background — light emitted during an even earlier era of the universe — as seen from Earth. That distortion, called gravitational lensing, reveals the distribution of dark matter around those galaxies, scientists report in the Aug. 5 Physical Review Letters .
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Understanding how dark matter collects around galaxies early in the universe’s history could tell scientists more about the mysterious substance. And in the future, this lensing technique could also help scientists unravel a mystery about how matter clumps together in the universe.
Dark matter is an unknown, massive substance that surrounds galaxies. Scientists have never directly detected dark matter , but they can observe its gravitational effects on the cosmos ( SN: 7/22/22 ). One of those effects is gravitational lensing: When light passes by a galaxy, its mass bends the light like a lens. How much the light bends reveals the mass of the galaxy, including its dark matter.
It’s difficult to map dark matter around such distant galaxies, says cosmologist Hironao Miyatake of Nagoya University in Japan. That’s because scientists need a source of light that is farther away than the galaxy acting as the lens. Typically, scientists use even more distant galaxies as the source of that light. But when peering this deep into space, those galaxies are difficult to come by.
So instead, Miyatake and colleagues turned to the cosmic microwave background, the oldest light in the universe. The team used measurements of lensing of the cosmic microwave background from the Planck satellite , combined with a multitude of distant galaxies observed by the Subaru Telescope in Hawaii ( SN: 7/24/18 ). “The gravitational lensing effect is very small, so we need a lot of lens galaxies,” Miyatake says. The distribution of dark matter around the galaxies matched expectations, the researchers report.
The researchers also estimated a quantity called sigma-8, a measure of how “clumpy” matter is in the cosmos. For years, scientists have found hints that different measurements of sigma-8 disagree with one another ( SN: 8/10/20 ). That could be a hint that something is wrong with scientists’ theories of the universe. But the evidence isn’t conclusive.
“One of the most interesting things in cosmology right now is whether that tension is real or not,” says cosmologist Risa Wechsler of Stanford University, who was not involved with the study. “This is a really nice example of one of the techniques that will help shed light on that.”
Measuring sigma-8 using early, distant galaxies could help reveal what’s going on. “You want to measure this quantity, this sigma-8, from as many perspectives as possible,” says cosmologist Hendrik Hildebrandt of Ruhr University Bochum in Germany, who was not involved with the study.
If estimates from different eras of the universe disagree with one another, that might help physicists craft a new theory that could better explain the cosmos. While the new measurement of sigma-8 isn’t precise enough to settle the debate, future projects, such as the Rubin Observatory in Chile, could improve the estimate ( SN: 1/10/20 ).
Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education.
