Land under the country's largest cities is sinking. Here's where — and why.
Researchers mapped out how land is moving vertically across the 28 most populous U.S. cities and found all the cities were compressing like a deflated air mattress. Twenty-five of them are dropping across two-thirds of their land. About 34 million people — about 10 percent of the U.S. population — live in the subsiding areas, according to the study published Thursday in Nature Cities.
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Associated Press
29 minutes ago
- Associated Press
Applied StemCell Appoints Dolores Baksh, Ph.D., as Chief Executive Officer
MILPITAS, Calif., Aug. 21, 2025 (GLOBE NEWSWIRE) -- Applied StemCell, a genome engineering product and services company, announced today the appointment of Dolores Baksh, Ph.D., as Chief Executive Officer. Company founder and former CEO Ruby Tsai, Ph.D., will continue to guide scientific strategy, innovation, and strategic collaborations as President and Chief Scientific Officer (CSO). 'Dolores brings exactly the kind of leadership we need to help scale Applied StemCell,' said Dr. Tsai. 'Her deep experience in commercializing advanced therapies, combined with her ability to execute high growth-oriented strategies, makes her an ideal partner for our next phase of growth. I am excited to focus on the tremendous opportunity to advance Applied StemCell's proprietary genome engineering platforms to help accelerate the adoption of cell and gene therapies.' Dr. Baksh joins Applied StemCell with more than 20 years of leadership in the life sciences industry, including prior roles as founding CEO of Hyperius Biotech and CEO of TAAV Biomanufacturing Solutions. She has helped build and scale companies at the forefront of cell and gene therapy manufacturing, with a focus on enabling technologies that improve quality, reduce cost, and accelerate access for patients. 'I'm thrilled to join Applied StemCell at such a pivotal time,' said Dr. Baksh. 'Ruby and the team have built a remarkable foundation of innovation, and I look forward to helping amplify that legacy by expanding our commercial reach, accelerating new product development, and forging partnerships that translate scientific breakthroughs into real-world impact.' Applied StemCell is known for its proprietary TARGATT™ large knock-in technology, custom iPSC services, and GMP-compliant cell lines that support both research and therapeutic development. With Dr. Baksh's appointment, the company is poised to strengthen its position as a trusted partner to biopharma companies advancing next-generation therapies. About Applied StemCell Founded in 2008 to provide industry and academic researchers with the ability to leverage the power of gene editing and induced pluripotent stem cells (iPSC), Applied StemCell continues to use our innovative technologies to power the discovery and development of advanced therapeutics. With a focus on genome engineering products and services, our patented technologies ensure a clear IP path to commercialization. For media inquiries, please contact: Pia Abola, Ph.D. Director of Marketing Applied StemCell A photo accompanying this announcement is available at
Medscape
an hour ago
- Medscape
ECG Challenge: Cardiomyopathy and an Irregular Rhythm
A 67-year-old man with a history of dilated cardiomyopathy and a left ventricular ejection fraction of 40% presents to his primary care provider for a routine physical examination. His vital signs and blood pressure are normal, but he has an irregular pulse. Figure 1. Courtesy of Philip J. Podrid, MD. The correct diagnosis is sinus rhythm, PVCs, and echo beats (Figure 2). Figure 2. Courtesy of Philip J. Podrid, MD. Discussion The rhythm is irregular with a repeating grouped beating pattern, with three QRS complexes and a pause. Therefore, the rhythm is regularly irregular. The average rate is 42 beats/min. The first of three QRS complexes has a normal duration (0.08 sec) and morphology. The axis is physiologically leftward between 0° and -30° (positive QRS complex in leads I and II and negative in lead aVF). This QRS complex is preceded by a P wave (+), which is positive in leads I, II, aVF, and V4-V6. The PR interval is constant (0.16 sec). Therefore, this is a sinus complex. The QT/QTc intervals are normal (420/350 msec). The second QRS complex (^) is wide (0.14 sec), and it has an unusual morphology not typical for either a left or right bundle branch block. There is positive concordance from V1-V5, although there is an S wave in V6. This QRS complex is not preceded by a P wave. Therefore, this is a PVC. The third QRS complex is identical to the first and is therefore supraventricular. This QRS complex is preceded by a P wave (*) that is negative in leads II and aVF, and positive in aVR. Therefore, this is not a sinus P wave. Because it is negative in lead aVF, it originates from either the atrioventricular (AV) node (ie, retrograde) or the low part of the atrium. There is a fixed relationship between the PVC and the negative P wave, so it is likely a retrograde P wave resulting from ventriculoatrial (VA) conduction from the PVC. The supraventricular complex that follows the PVC is therefore termed an echo complex. An echo complex occurs with a preceding QRS complex that is not preceded by a P wave (junctional, ventricular, or paced complex) and is associated with intact VA conduction. Intact VA conduction may lead to retrograde activation of the atrium (retrograde P wave). Given the right timing, this retrograde atrial impulse can then enter the AV node and His-Purkinje system to restimulate the ventricles in an antegrade direction (ie, it echoes back to the ventricles). Philip Podrid, MD, is an electrophysiologist, a professor of medicine and pharmacology at Boston University School of Medicine, and a lecturer in medicine at Harvard Medical School. Although retired from clinical practice, he continues to teach clinical cardiology and especially ECGs to medical students, house staff, and cardiology fellows at many major teaching hospitals in Massachusetts. In his limited free time, he enjoys photography, music, and reading.
Yahoo
an hour ago
- Yahoo
Inside NASA's Wild Space Mission to Defend Earth Against a Planet-Killing Asteroid
On the count of three, engineers in the Johns Hopkins University control room erupt in cheers. It's early fall 2022, and amid rows of computer monitors and a dozen television screens, the team exchanges high fives and congratulations. Then a new countdown begins, and the engineers get back to work preparing one of the most important NASA missions this century. For weeks, Elena Adams has been leading her team at the Applied Physics Laboratory (APL) in Laurel, Maryland, through rehearsals of NASA's Double Asteroid Redirection Test (DART). The mission represents the agency's ambitious bet that it can take aim at asteroids on a collision course with Earth and strike them with a projectile, nudging them far enough off course to prevent a world-ending impact. The mission is still weeks away. But as DART's head engineer, the strong-willed yet unceasingly joyful Adams wants to ensure that her team is ready for any outcome. With more than a decade of experience at APL and a black belt in tae kwon do, Adams has fearlessly led her team through building and testing the spacecraft. No detail can be overlooked, so today the team members are practicing how they'll react to a successful mission, right down to those celebratory high fives. They're also preparing to stomach the worst: missing the asteroid entirely. The whole world will be watching us, she recalls thinking. So if the mission succeeds, she says in her slight Russian accent, 'we're not going to do this lame handshake thing.' Though the days are fast ticking by, that success is far from assured. DART is the first-ever test of what NASA calls a kinetic impactor—a projectile intent on transferring its momentum to an asteroid in an elegant suicidal smash. In other words, the team plans to ram a speeding spacecraft into an asteroid to knock it off its path. The logistics are mind-boggling. DART's target, a few million miles from Earth, is only the size of a tall building, the smallest asteroid ever visited by a spacecraft. The craft will be traveling at thousands of miles per hour; accurately reaching the asteroid is akin to throwing an arrow from southern France and hitting an apple on the U.S. East Coast. The slightest error would cause DART to blast by its target in an instant, rendering the $325 million mission moot. Making the task even more challenging, the engineers assembled at APL will cede control of their craft for the final moments of the mission. DART is designed to operate its last hours autonomously, located too far from Earth for fast manual corrections to its trajectory. Adams knows that if all goes according to plan, a successful impact—and her team's celebrations—will be witnessed by a worldwide audience. So she runs the drill again, guiding the scientists as they attempt to ensure that humanity won't meet the same fate as the dinosaurs. Planetary defense scientists were at first a small, hardy bunch. A hodgepodge field encompassing astronomers, planetary scientists, and engineers, it united around taking seriously the question of how to protect Earth from cosmic threats, including impacts from asteroids and comets. At astronomy conferences in the late 1990s and early 2000s, they worried about 'the giggle factor'—the sense that their work veered toward science fiction. To Naomi Murdoch, a planetary scientist at France's ISAE-SUPAERO who researches asteroids' surfaces and evolution, asteroids are fascinating but also potentially dangerous. Like planets, asteroids are rocky objects locked in slow, orbital dances around the sun. Ranging in diameter from a few feet to 300-plus miles, they are cosmic leftovers from when our solar system formed more than four billion years ago. Over the past few decades, astronomers have used ground- and space-based telescopes to detect over 38,000 near-Earth asteroids, defined as those whose closest distance to the sun comes within 1.3 times the average distance between our planet and the sun. Fewer than 30 percent are deemed 'potentially hazardous asteroids,' those that are at least 460 feet wide. NASA predicts that one of those could impact Earth once every 10,000 years. Three percent exceed 0.6 mile in diameter and could strike our planet with devastating results once every few hundred millennia. Murdoch first joined planetary defense efforts in 2007, after she learned that scientists were already considering how to deflect rogue asteroids by bumping into them. 'The probability is low that an asteroid will hit us,' she says. 'But at the same time, it is the only natural disaster that we can predict and act against.' Even still, prediction efforts aren't always airtight. In February 2013, a house-sized asteroid exploded above Chelyabinsk, Russia, releasing the energy of nearly a half million tons of TNT and injuring 1,600 people. The asteroid's fiery descent to Earth had been missed by space agencies but captured on the dashcams of Russian cars as it shattered windows and caused tens of millions of dollars in damages. Chelyabinsk was a wake-up call. Planetary defense scientists now had the attention of space agencies across the globe. That year, NASA turned to a European planetary defense proposal that had been floating around the space community for a decade. Called Don Quijote (reflecting the Spanish spelling of the popular novel's title), the idea went beyond asteroid monitoring into asteroid deflection, suggesting that one spacecraft ram into an asteroid and a second craft photograph the crash so scientists could perform real-time forensics. While space agencies had landed satellites on asteroids before—and even designed one to deliberately smash into a comet with NASA's Deep Impact mission in 2005—no one had ever set out to move a target. Doing so would rely on an engineering concept many learned in high school science: exchanging momentum between a gumball (a spacecraft) and a bowling ball (an asteroid). NASA and its partners began designing an entirely new craft that could travel on a precise trajectory at thousands of miles per hour, aimed at a target large enough to study but small enough to nudge off course. To lead the DART project, NASA selected APL, which had previously developed targeting algorithms for the U.S. Navy's air defenses and also oversaw NASA's first mission land on an asteroid. They'd work with Don Quijote scientists as well as the European Space Agency (ESA), which was tasked with building the secondary observer spacecraft. With $325 million to spend, the journey to protect Earth was on. But DART would be more challenging than any previous asteroid mission, and the stakes couldn't be higher. 'Planetary defense isn't the highest priority thing that we do here at NASA on a day-to-day basis,' Air Force veteran and NASA's planetary defense officer Lindley Johnson has said. 'But the day could come when it becomes the most important thing that we do.' If sending a spacecraft to bully an asteroid was an engineering challenge, determining if the collision worked would test the limits of astronomers to track tiny objects millions of miles away. APL scientists knew that a high-speed kinetic impactor such as DART might nudge the asteroid off course by a only few millimeters per second. (Astronomers calculate changes in an asteroid's trajectory by recording changes in the time it takes to orbit another object.) Such a tiny difference would be nearly impossible to measure from the observer spacecraft; instead it would require powerful ground-based telescopes to track the asteroid's orbit around the sun for years. Andy Cheng, then-chief scientist of APL's space department and DART's co-leader, had pondered that problem ever since Don Quijote was first proposed in 2003. Cheng, now in his 60s, was no stranger to the difficulties of studying asteroids; he had served as the project scientist for NASA's mission to land on a comet and spent a year as NASA's deputy chief scientist in addition to his then-30 years at APL. But while stretching one morning in 2011, Cheng had a light-bulb moment. Some asteroids—estimates hover around 15 percent—travel with a rocky companion in what's known as a binary system, where two asteroids orbit each other. If a kinetic impactor were to strike an asteroid's companion, Cheng realized, astronomers could measure how much its orbit changed around the main asteroid, where one cycle takes hours, not years. 'The idea wouldn't leave my head,' he recalls, and upon hearing it, his colleagues agreed that the plan could solve one of DART's biggest barriers. The next step was to pick the victims: Didymos and Dimorphos, a pair of asteroids with diameters of a half mile and 525 feet, respectively. The larger had first been spotted in 1996; its smaller companion was discovered in 2003. The duo, whose names mean 'twin' and 'two forms' in Greek, takes about two years to journey around the sun, never posing a threat to Earth. The timing was perfect: In the fall of 2022, they would be around 6.7 million miles away, the closest they would be for the next 40 years. The closeness of the binary crucially meant that ground-based telescopes would be able to photograph the consequences of the collision. So while Adams and her engineers designed the spacecraft for its intended target, Cheng worked with Nancy Chabot, DART's coordination lead in charge of overseeing the science teams, to gather a crew of astronomers to watch it explode. The team recruited Tim Lister, an astronomer and astrophotographer based at Las Cumbres Observatory near Santa Barbara, California, a worldwide telescope network built to observe fleeting events like asteroid movements. DART 'was a chance to be involved with a mission that was going to demonstrate what we could possibly do to save the Earth,' says Lister. When approached about bringing Las Cumbres on board, it was an easy yes for him. To determine how much the orbit of Dimorphos around Didymos changed after impact, Lister and other team members would first need to nail down its existing path, using an astronomy technique called a light curve. Planets, moons, comets, asteroids, and even grains of space dust all scatter light like a glass bead catching an afternoon sunbeam. Telescopes observe this scattered light—the light curve—to track the object. In a binary system, when a smaller asteroid passes in front of a larger one, the amount of scattered light dips momentarily, as if a wandering fly blocked part of the glint from the bead. By tracing the periodic dips in Didymos's light curve, astronomers could see how long it took Dimorphos to orbit its companion: approximately 11 hours and 55 minutes. The same technique would be used after impact, along with precise radar measurements. Together they would help reveal if that orbit stretched by a few seconds, or even minutes—a sure sign that the rock pile had been sufficiently knocked off course. While determining Dimorphos's new orbit was the astronomers' main goal, the mission also offered the rare opportunity to study an asteroid up close. Planetary scientists knew where Dimorphos and Didymos were in our solar system and about how big they were, but little else—not their masses, composition, or surface texture. Everything scientists learned about these asteroids could inform critical kinetic impactor missions in the future, when human lives were at stake. 'Asteroid surfaces are really unintuitive places,' says Murdoch, a veteran of ESA's early planetary defense efforts who helped develop models of how the surface of Dimorphos might respond to DART. 'We're often too biased by what we see on Earth to correctly predict what's going to happen.' Every new variable tested by Murdoch and the science team—from the composition of Dimorphos's surface, to the angle of impact, to the mass of the asteroid—yielded wildly different results. During some simulations, the asteroid barely budged; in others, DART plowed into the rocky surface, knocking Dimorphos way off course. But after years of work creating simulations that sometimes took weeks to run on supercomputers, the team had narrowed in on a goal: striking the small asteroid with enough oomph to increase the time it took to orbit Didymos by 73 seconds. Seven to 10 minutes would be a triumph. Then, two major crises shook the DART team. The first came in December 2016, when ESA couldn't secure enough funding for its observer spacecraft and canceled the program. With the mission severed in half, 'we questioned whether NASA would also pull out,' Chabot says. 'It was a pretty dark time.' But NASA remained committed, and thoughts turned to how to continue. First, they needed to reassemble the crew. 'We weren't just gonna kick all of our European scientists off the team,' says Chabot—a group that included Murdoch and the visionaries behind Don Quijote. So DART took the unusual step of allowing non-NASA-affiliated scientists to participate, which included people from 29 countries, some joining only months before impact. If 'they had something to contribute, we would welcome them in,' Chabot says. NASA then needed to find a replacement for ESA's observer spacecraft. The team turned to Italy, which had volunteered to design and operate a stowaway instrument called the Light Italian Cubesat for Imaging of Asteroids, or LICIACube. No larger than a shoebox, LICIACube would pop out of a spring-loaded compartment on the spacecraft 15 days before impact to get its space bearings in time to photograph our first cosmic clash with an asteroid. Borrowing from a design used on NASA's Artemis I mission, the Italian aerospace company Argotec would have less than three years to build the tiny satellite. Back in the APL clean room, Adams and her team were hard at work engineering the main spacecraft, which faced a grueling hundred-million-mile journey across the blackness of space. Integration Review, a NASA checkpoint to determine whether a mission is permitted to proceed with assembling and testing a spacecraft, was fast approaching. Before starting to build, the team needed to prove that every component of the craft could perform as expected—and survive long enough to do so. The first peril for the spacecraft would be its launch upon a SpaceX Falcon 9 rocket, with vibrations violent enough to rattle its instruments loose or disrupt its sensitive electronics. It would also face both blistering and chilling temperatures in space, as well as the force of traveling at four miles per second—about 26 times faster than a commercial jet. Even more exacting, DART would also rely on new variations of three mostly unproven technologies: giant solar arrays to power its flight once in space, an ion propulsion system, and autonomous navigation software called the Small-body Maneuvering Autonomous Real Time Navigation System (SMART Nav). Led by APL software systems engineer Michelle Chen, SMART Nav would take the wheel for the craft's final four hours to avoid the 1.5-minute time delay between human commands and spacecraft execution. With the spacecraft traveling at breakneck speeds, the software would need to be highly efficient, processing an image from DART's camera and telling the craft where to point while preserving fuel—all within a second. In March 2020, Adams led the DART team as they sailed through the Integration Review. Then, with less than a year and a half to launch, the second crisis arrived: The COVID-19 pandemic sent everybody home. As Adams watched her computer screen fill with boxes of her colleagues' faces, she wondered how her team could possibly engineer the mission from quarantine. 'You can't put a spacecraft together without actually being there,' she says. Though most normal activities on Earth had screeched to a halt, Didymos and Dimorphos still journeyed around the sun right on schedule. So, after a few weeks of quarantine, a small group of engineers returned to APL as essential workers. Ironically, strict air filtration standards for spacecraft builds made the clean room a safe environment. The once-bustling floors were eerily quiet, with machinery and tools left where they were last used before quarantine. Large platforms suspended spacecraft parts underneath ceilings that towered 60 feet. Engineers wore the usual uniform—white lab coats, booties, gloves, hair nets—but added face masks, some sewn by the APL personnel who make thermal blankets for spacecraft. The jobs of dozens of engineers were completed by only a handful, staggering in shifts to assess the spacecraft one by one. Supply-chain issues abounded, and those assembling the spacecraft were forced to inspect parts manufactured by contractors over Zoom. Other engineers dialed in from home. 'I can't tell you how many times I watched screws being put in remotely,' Adams says. Amid the challenges of lockdown came confounding engineering hurdles. When a model of DART's camera was put through a launch vibration simulation, its mirror shattered, prompting a redesign of its mounts. And the star trackers, which would help the camera point, seemed to capture too much noise. That required another redesign of its mounts. Then, in February 2021, the team faced another hurdle: NASA leadership pushed back the launch date by four to six months. The decision, due to supply chain issues and a need to reinforce and retest the camera mirror for launch stress, was 'a really tough time' for the project, Chabot says. While the spacecraft would still arrive at Dimorphos in fall 2022, there was less time to work out any post-launch kinks. In other words: There would be no margin for error. Finally, launch day arrives—November 24, 2021. Engineers gather at California's Vandenberg Space Force Base, many of them together for the first time since the start of the pandemic. With hearts in their throats, they watch as the product of years of their work begins to shake violently, carried up into the cosmos aboard a fiery SpaceX Falcon 9 rocket. Humanity's first cosmic roughhouser officially begins its journey at 1:21 a.m. ET; no parts break on the ascent. Mission operators at APL coax DART to release its solar arrays around 4 a.m.; each of these has been designed to unfurl from compact cylinders to 28 feet in length once airborne. After two weeks, the camera begins surveying the twinkling stars that will guide it over the next 10 months to its final destination. Though its path is set on Dimorphos, the camera takes some time to stargaze, snapping more than 150,000 pictures of celestial bodies as engineers at APL calibrate its optics. The first problem arises a few short weeks away from impact, when it becomes apparent that the star trackers are still catching too much noise. The engineers discover that when a certain heating system turns on, the trackers can drift by 20 microns—about 20 percent of the width of a human hair. That's enough to make DART miss its target half of the time. So they hastily write new software that will allow the spacecraft to cycle heat differently. NASA has fitted the craft with a secondary ion-propulsion system that uses xenon propellant, which it wants to test for future missions. Now that's causing problems too. During a trial run, engineers spot strange readings from DART's power system, forcing them to stop the propulsion system and rely solely on the main thrusters to avoid endangering the spacecraft. As impact day approaches, preparations ratchet up. In July 2022, powerful telescopes in Arizona and Chile confirm the orbit and location of Dimorphos. At APL, Adams and her colleagues, now working in person, lead practices of every scenario they can dream up, including one in which Dimorphos turns out to be donut-shaped and they fly right through its belly. Chen's team tests SMART Nav's targeting using the moons of Jupiter. LICIACube deploys successfully. Astronomers track other asteroids as test runs for impact. And Lister refines the software he plans to use for the light curves, finally getting it working just two days ahead of the scheduled collision. 'We get exactly one shot at this,' says Lister. 'We couldn't just tell the spacecraft to back off a bit and do it tomorrow because we're not quite ready yet.' On September 26, 2022, thousands of astronomers, planetary scientists, and engineers gather at watch parties around the world to follow NASA TV's livestream of DART's final hours. Their screens show the spacecraft camera's view, one jolting photo every second. In the APL control room, the team of engineers work away at their computers, buoyed by specially made fortune cookies that Adams had snuck under their chairs before work with messages that read, 'Today you will make an impact.' With four hours to go until the planned collision, SMART Nav takes the reins. Though DART has been targeting Dimorphos for months, its cameras won't pick up the asteroid until it is an estimated 90 to 75 minutes away, which it will transmit back to APL as a tiny pixel of light. Didymos, which had come into view as a large, gray mass 45 days earlier, still fills much of the screen. Despite the practice runs, Adams, with Chen sitting behind her, watches excitedly as the minutes tick down. Hundreds turn into 90, then 80. If Dimorphos doesn't appear from behind Didymos by 70 minutes to impact, the engineers need to consider manually intervening to retarget. When the clock hits 75, Adams pulls a few people into a huddle. She doesn't need to remind them that if DART missed, an accurate U-turn would take two years, and there wasn't enough fuel on board for that. Then, with 73 minutes remaining, a new pixel of light appears on screen, the team's first glimpse of the tiny asteroid. For the next hour, Dimorphos remains just a speck of light on the NASA screens, not much different from the stars that had guided its journey. With two and a half minutes and 500 miles left, SMART Nav turns off to avoid transmitting shaky images, leaving the spacecraft coasting undirected by people or software. Like a game of darts, SMART Nav has taken its aim at the board; the spacecraft will either hit a bull's-eye, or miss the target. Moments later, Didymos slides out of view, indicating that SMART Nav has correctly narrowed in on Dimorphos. Finally, with just a minute to impact, the asteroid's crater-pocked, boulder-filled surface appears on screen, revealing itself for the first time to the legions of scientists following the project. From California to Maryland, cheers ring out: DART is headed straight for the center, which thankfully looks nothing like a donut. At 7:14 p.m. ET, the last image fills the televisions of the APL control room: a horizontal sliver of gray, jagged boulders before the image cuts out to piercing red static, DART's last attempt to communicate home over seven million miles of cold, dark space. Impact. Despite the preparations, the celebrations feel organic. 'I think we had like five or six different cheers [rehearsed],' Chen says. But 'the look on everybody's faces... there's no way you could rehearse that.' After hugging her team, Adams steps out of view of the cameras and cries. 'Emotionally, you've been running so fast for so long,' she says. 'We all came in the next day not knowing what to do.' For Adams and Chen, the work is largely over. But hundreds of scientists around the world are getting started on the mission's next phase. Scientists had estimated that gathering enough observations to calculate the new orbit of Dimorphos around Didymos—the proxy for DART's success—would take weeks, followed by an extensive campaign to study its composition and shape. But at 3 a.m. PT, from his home in Southern California, Shantanu Naidu, a radio astronomer with NASA's Jet Propulsion Laboratory, logs on to his work computer to check the initial radar observations. He finds that Dimorphos is out of sync with his earlier predictions—by a lot. While NASA had hoped for a 73-second orbital bump, Naidu sees a staggering change. The asteroid's orbit appears to have stretched by 36 minutes. 'I didn't tell anyone about these results,' he later said, worried that they were too extreme to be accurate. 'Maybe I should wait for the next day's data.' But the excitement is too great and he shares his estimates to the DART team over Slack less than 24 hours after impact. The news spreads fast within the team. And as 42.5 cumulative days of observations across telescopes on all seven continents eventually confirm, Naidu isn't far off. Dimorphos's orbit around Didymos has shortened from 11 hours 55 minutes to 11 hours 22 minutes—a whopping 33 minutes, plus or minus two. 'We were pretty floored,' says Chabot. Then the trickle of results turns into an avalanche of exciting observations. 'As nighttime would go around the globe... [results] were just coming in hour after hour after hour,' Chabot recalls. The scientists first notice a giant, high-speed plume of ejecta rising from Dimorphos's surface, then watch as it forms into tails tens of thousands of miles long that follow the asteroid for weeks. Photographed with LICIACube, ground-based observatories, and even the Hubble and James Webb Space Telescopes, the plume of dust and boulders is so large—10,000 tons in total—that some astronomers initially speculate that DART has blown up the asteroid entirely. 'What the heck is that? Is that real?' Lister recalls asking his colleagues. While Dimorphos had not in fact exploded, scientists discover that it is a type of asteroid known as a 'rubble pile,' a loosely held conglomerate of boulders prone to dramatic spews of material when hit. Planetary scientists think the release of material gave the asteroid some kickback, pushing it even farther off its orbit around Didymos. However, the moment wasn't entirely explosion-free: part of the plume was unused xenon gas from the faulty ion thruster. In the following weeks, planetary scientists also learn that DART's impact had set Dimorphos on a slightly unstable course around Didymos, wobbling like a top. They even find that the impact changed Dimorphos's shape from a lumpy sphere to an elongated watermelon, taking a chunk off with it. The DART mission officially ended in the fall of 2023 when the binary system traveled too close to the sun for telescopes to follow it. To keep studying the changes to Dimorphos and inform any future kinetic impactors, ESA's Hera spacecraft will arrive at the cosmic crime scene in December 2026. For now, asteroid monitoring efforts will continue in force, buoyed by DART's success. 'We have no idea how to prevent hurricanes or earthquakes,' NASA's Johnson says. 'But we're a long ways now along the road of preventing an impact from an asteroid or comet.' For the first five decades of its existence, NASA was tasked with exploring the cosmos and Earth's place within it. But the more astronomers learned about the space rocks whizzing by our pale blue dot, the clearer it became that knowledge couldn't protect us from a wayward asteroid any more than scales and spikes protected the dinosaurs. If we wanted to persist in space, we could no longer be cosmic bystanders. Millions of miles away, a chunk of boulders glued together by gravity and forged from the same ancient elements that built the planets likely has a missing chunk etched by a vending machine–sized hunk of metal. A newly laid sign, for any meandering asteroids nearby, that Earth now packs a Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life? Solve the daily Crossword
