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Yahoo
4 days ago
- Business
- Yahoo
SpaceX's Ninth Starship Test Flight Delivers Mixed Results
In its ninth test flight, SpaceX's launch vehicle Starship once again reached space, surpassing problems that prematurely ended its two previous test launches. But as with those ill-fated preceding flights, in this one, Starship still failed to reach the ground intact. Instead the vehicle spun out of control and disintegrated during atmospheric reentry. Although each Starship test thus far has succeeded in demonstrating powerful new technical advances that are crucial for the program's further progress, this marks the third flight in a row in which the titanic vehicle suffered a 'rapid unscheduled disassembly' that sent fiery debris cascading down to Earth. All that effort, it's hoped, will prove worthwhile if or when Starship enters regular operations because SpaceX aims to make the vehicle, by far, the largest and most capable fully reusable spacecraft ever flown. In the latest test, around 50 minutes after launch, SpaceX confirmed that Starship met its demise. At first, everything in the vehicle's flight appeared to be going well. Starship—a 40-story-tall 'stack' that is composed of a giant, 33-engine Super Heavy booster and a 171-foot-long spacecraft powered by six additional engines—lifted off as planned from SpaceX's launch site in Starbase, Tex., at 7:37 P.M. EDT on Tuesday. But cheers were somewhat subdued until about 10 minutes after launch—when operators officially determined that the spacecraft's trajectory was nominal, taking it on a ballistic suborbital path through outer space. [Sign up for Today in Science, a free daily newsletter] 'Ship engine cutoff—three most beautiful words in the English language,' declared Dan Huot, a communications manager at SpaceX, during the company's livestream of the flight test near the launch site. Around him, sighs of relief could be heard as SpaceX employees began to ascertain that the day's flight would not be a repeat of the previous two, each of which had resulted in the vehicle exploding over the Atlantic Ocean less than 10 minutes after launch. Around 18 minutes after Tuesday's launch, however, issues began to emerge. First, operators decided not to deploy Starlink satellite demonstrations as planned because of a stuck payload door. Then, about a half an hour after launch, SpaceX mission control reported that suspected propellant leaks were driving the vehicle into a spin, which doomed it to burn up in the atmosphere during reentry—raining debris over the Indian Ocean. 'We're not going to get all of that reentry data that we're still really looking forward to,' Huot admitted in the livestream. 'This is a new generation of ship that ... we're really trying to put through the wringer, as there's a whole lot we still need to learn.' Meanwhile, although the Starship vehicle itself showed improved performance, the Super Heavy booster that helped it reach space ran into problems of its own. Moments after firing its engines to come in for a landing in the Atlantic Ocean, the booster instead broke apart. This wasn't entirely unexpected; in keeping with SpaceX's 'test to failure' approach, the Super Heavy had attempted to reenter in a different, potentially fuel-saving orientation that subjected the booster to more intense aerodynamic forces. Despite its unplanned disassembly, the booster did mark a significant milestone for SpaceX: for the first time, it flew with a nearly full suite of flight-proven engines that were previously used during Starship's seventh test. And the booster remains a marvelous demonstration of SpaceX's innovation; a Super Heavy previously made spaceflight history when it became the first rocket ever to be caught in midair with two mechanical arms. In the new launch, the Super Heavy was able to do its intended jobs of bringing Starship to space and testing new reentry techniques, explained Jessie Anderson, SpaceX's senior manufacturing engineering manager, during the flight's livestream. 'There's always a chance we don't reach every objective that we set for ourselves,' Anderson added, 'but success comes from what we learn on days like today.' On X, former NASA deputy administrator Lori Garver praised SpaceX's transparency but noted these were 'not the results we were hoping for.' Garver was instrumental in forging the space agency's partnership with SpaceX, which helped spark the company's unprecedented dominance of commercial launch services upon which NASA now heavily relies. Starship is the prized cornerstone of SpaceX's ambitious plan to build human settlements on Mars and is also slated to ferry crews to the lunar surface in a couple of years for NASA's Artemis III mission. Given the high stakes for the vehicle, its test program's mixed results are disappointing, to say the least. Notably, the previous two attempts, Flights 7 and 8, each ended with two spectacular explosions over the Atlantic Ocean. For Flight 8 in particular, the engines shut down unexpectedly minutes after launch, causing the spacecraft to essentially fall apart and self-destruct in midair. SpaceX received some public backlash after the spacecraft debris, which the company claimed would pose minimal risks, led to multiple midflight diversions for passenger airplanes that were under threat. Nevertheless, SpaceX appeared stalwart and even optimistic about Flights 7 and 8, calling the latter's mishap an 'energetic event' that occurred because of hardware complications. Last week the company said both explosions had a 'distinctly different' cause. And in a press release that followed the launch of Flight 9, it noted that Flight 8 greatly informed the upgrades and modifications to Starship for the latest test. 'Developmental testing by definition is unpredictable,' SpaceX said in a prelaunch press release for Flight 9. 'But by putting hardware in a flight environment as frequently as possible, we're able to quickly learn and execute design changes as we seek to bring Starship online as a fully and rapidly reusable vehicle.' What does Starship's questionable status mean for SpaceX's long-touted goal of 'making life multiplanetary'? If anything, it suggests the company's projections for the vehicle's regular, routine operation have been and remain unrealistically optimistic. Last year SpaceX founder Elon Musk stated in a social media post that the company plans to launch 'about five' uncrewed Starships to Mars in two years. In another post shortly after Flight 9's mixed results, he touted the vehicle's partial success and predicted that the next few flights would occur at a fast pace of about one per month. Whether or not such haste is feasible, it would certainly be desirable, given the pressure SpaceX faces to deliver on its lofty promises.
Yahoo
5 days ago
- Politics
- Yahoo
Upgraded Very Large Array Telescope Will Spot Baby Solar Systems—If It's Funded
New Mexico's Plains of San Agustin are otherworldly: Silence, sand and sharp plants reign on the valley floor. Knobbly volcanic rock rises above. Pronghorns' legs and jackrabbits' ears break up the landscape. And so, too, does one of the world's largest telescopes. The plains house the aptly named Very Large Array (VLA)—a radio telescope made of 27 different antennas, each of which looks like a home satellite dish on steroids. In the otherwise empty desert, they spread into a Y shape that can extend 22 miles end-to-end. When the antennas are pointed at the same thing in the sky at the same time, they function together as one large telescope, simulating an instrument as wide as the distance between the dishes. In this case, then, images from the VLA have as much resolution as they would if it were a single telescope 22 miles wide: high definition, in other words. The VLA became iconic, and inspirational to a generation of astronomers, thanks to the movie Contact, in which Jodie Foster's character uses the array to hear an alien communication. [Sign up for Today in Science, a free daily newsletter] The VLA's antennas, the true stars of the film, simultaneously look like they don't belong in the landscape and also like they've always been here. They haven't, of course, but their construction began in the 1970s, making the VLA the oldest instrument in the portfolio of the National Radio Astronomy Observatory (NRAO). This federally-funded organization builds, maintains and operates radio telescopes that any astronomer—regardless of their institutional affiliation or citizenship—can apply to use. But the VLA, now in its middle age, is due for a replacement. After all these decades, astronomers want something shiny, fully modern and more capable: a new build with all the bells and whistles rather than a charming old Colonial that's been remodeled piecemeal. NRAO is working on that, planning the VLA's proposed successor: the Next-Generation Very Large Array (ngVLA). (Astronomers may be scientifically creative, but they are linguistic straight shooters.) On a Friday afternoon in late April, the organization gathered political leaders together, alongside scientists and engineers, to unveil a prototype antenna—one that will be cloned a couple of hundred times to make up the future ngVLA. It loomed on the plains just beyond the partygoers, standing alongside its predecessors, the old and the new in stereo with each other. 'The amount that technology has advanced since the VLA was created is amazing,' says Jill Malusky, NRAO's news and public information manager. 'A VLA antenna and an ngVLA antenna look very different because they are.' Guests wandered near the antennas, checking out a spread of food that included a sculpture, made in the medium of watermelon, of a radio telescope antenna. A chamber quartet played in the background, a single fern fronting them, with an open bar lubricating the event. It was fancy—for science. But for astronomers, the ngVLA is a big deal, and the event was intended, in part, to bolster the political support needed to make it happen. At the moment, it's a proposed project—and still requires final funding. 'Having a physical antenna we can point to, and test, to prove the value of this project is such a milestone,' Malusky says. 'It makes it all more real.' Representing an orders-of-magnitude improvement to the VLA that would complement other radio telescopes in the U.S. and abroad, the ambitious project has the enthusiastic yes of the astronomical community. But whether big-science telescopes, radio or otherwise, will survive the current funding environment remains a dark matter. That uncertainty is part of why NRAO's event elicited a spectrum of emotions for Malusky. 'It's a mix of excitement and trepidation,' she says. 'Can we get people invested in the potential of a major project that is still gathering resources and just over a decade to fruition?' That Friday afternoon, Tony Beasley, director of NRAO, stood at the front of a hardy event tent and faced the prototype. Its dish was made up of shiny panels assembled into an octagon. From its bottom edge, supportive struts held up a secondary reflecting surface and a receiver (basically the radio version of an optical telescope's camera) that looked a bit like the spaceship Foster's character boarded in Contact. The antenna, about as wide as a bowling lane is long, has been designed to collect radio waves from space—beamed from stars that are being born or dying, the stuff between stars, and more. As radio light comes in, it will hit the main dish and bounce up to the secondary reflector and then the receiver, which will catch the waves and turn them into digital signals that will then be sent to computers. As a start, the prototype dish will hook up to VLA's aging ones and gather data alongside them—it will be an apprentice of sorts. 'You see one antenna out there,' said Beasley, directing the audience's attention beyond the tent, which was being shaken by the wind to such an extent that people also cast their eyes upward to assess its structural integrity. NRAO ultimately plans to build 262 more antennas and spread them across the U.S., with their numbers concentrated in the Southwest. Of those antennas, Beasley continued, '192 of them will be visible from where I'm standing right here.' Together, the ngVLA's antennas could pick up a cell-phone signal from 500 billion kilometers (more than 310 billion miles) away (although that wouldn't be the most likely find). That means it could detect an Android embedded in the Oort Cloud, the collection of comets that makes up the outer part of the solar system. The future telescope's resolution should be high enough to pass a no-glasses eye exam in New York City if the chart of letters were placed in Los Angeles. That precision gives it scientific latitude, allowing it to address some of astronomers' highest-priority questions, such as how planets come to be and how solar systems like ours form. 'You could, say, probe a cloud that is forming planets and find out where the planets are—like individual gaps in the cloud that the planets are carving out,' says David Kaplan, an astronomer and physics professor at the University of Wisconsin–Milwaukee. Of all the radio telescopes out there, the ngVLA would be the planetary 'flagship' for star and planet formation, Kaplan says. At high radio frequencies and big antenna separations, 'it would be the only game in town.' The ngVLA will also look for the organic molecules and chemical conditions of new solar systems that might someday spur life. It will show how galaxies come together and evolve, use the Milky Way's center to test ideas about how gravity works and investigate how stars develop. And it will hunt black holes and their outbursts. Given those varied abilities, the telescope was highly ranked in astronomers' 'decadal survey,' a yearslong process in which the astronomical community takes stock of its most valued scientific questions and assesses which future telescopes are best suited to find some answers. Funding from agencies such as the National Science Foundation (NSF), which bankrolls NRAO, typically follows the survey's recommendations. The survey recommended the ngVLA as a top priority. 'It can change the landscape,' says Matt Dobbs, a physicist at McGill University, who studies the origin and evolution of the universe and worked on the survey alongside Kaplan. NRAO hopes to start construction on the ngVLA in 2029, with initial operations beginning in 2033. The possibility is a bright spot for American radio astronomy. The VLA is more than 40 years old; the Green Bank Telescope, completed in 2001, is more than 20. And NRAO's latest instrument, the Atacama Large Millimeter/submillimeter Array, opened 12 years ago. The latter two, though not new, aren't going anywhere, as far as anyone knows. But they do different kinds of scientific analyses than the VLA does and the ngVLA will. The new telescope does, though, have a whippersnapper nipping at its heels. Another future radio observatory, called the Deep Synoptic Array 2000 (DSA-2000), is planning an order of magnitude more dishes than the ngVLA—2,000 of them. But each will be only around 16 feet across, whereas ngVLA's dishes will measure 60 feet. DSA-2000 will also work at a different radio frequency range than the ngVLA. DSA-2000's development is also moving faster than that of the VLA's successor, though, in large part, that is because the former has relied on private funding more than federal resources, as the ngVLA's prototyping has. In taking a step back from dependence on the NSF, the DSA-2000 crew might be on to something. Just days before the ngVLA ceremony, the NSF canceled more than 400 active grants; one day before, the agency's then director Sethuraman Panchanathan resigned. 'This is a pivotal moment for our nation in terms of global competitiveness,' he said in his goodbye letter. 'NSF is an extremely important investment to make U.S. scientific dominance a reality. We must not lose our competitive edge.' No one knows what the future of NSF-funded astronomy, let alone NSF-funded radio astronomy, looks like. President Donald Trump hasn't said much about that particular domain yet. But not building the ngVLA could put that edge in jeopardy. Dobbs, though, holds out hope for the U.S.'s role in radio astronomy's future, in part because of the propulsion of its past. 'The United States has everything it needs to make that project a reality,' he adds. Whether it will do so, though, requires gathering more data from the future. After all, it's bad luck to count your antennas before they hatch. Dobbs has been putting his focus on smaller radio telescopes, such as one called the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and its successor, acronymed CHORD. Both map how hydrogen was distributed in the early universe and detect fast radio bursts. Their antennas are cheap(ish), their overall footprint small, and their ambition is limited to specific science—in this case, gas maps. At the prototype-antenna unveiling, then, it made sense that there was a liminal feeling to what was otherwise a celebratory gathering. And it was conspicuous that representatives from NSF, the agency that would fund the telescope's construction and operation, weren't there, which Beasley said was the case 'for various reasons.' Chris Smith, interim director of the NSF's division of astronomical sciences, did send a letter to be read to the wined-and-dined crowd. 'NSF funded this development not just to ensure the technical feasibility of the advanced capabilities of ngVLA,' he wrote. It also supported the prototype as 'a way of creating new innovations in the field of radio astronomy.' And that may be true. But those who gathered at NRAO's event also hope, specifically, that the ngVLA, a receptacle for optimism about the future of radio astronomy in the U.S., will sprout from this dry ground. 'It starts with a single step,' Beasley said at the event—in this case, a single antenna.
Yahoo
6 days ago
- Entertainment
- Yahoo
The Applause for Jaws, Despite Flaws
The motion picture Jaws deserves another round of applause on its 50th birthday, despite its flaws. Released on June 20, 1975, this classic invented the summer blockbuster genre, made sharks a familiar (if demonized) foe, and gave a visceral picture to the words 'shark attack.' But today, humanity has grown to have a better appreciation for all sharks, even those that swim near the beach. We owe some of the public sentiment that it's 'safe to go back in the water' to Jaws. Initially, the movie's biggest impact was to portray shark bites as intentional "attacks" on swimmers. The fictional story of the human-shark relationship (and human-ocean relationship) that humans are on the menu—has been one of the most successful Hollywood narratives in motion picture history. More movies, sequels and spin-offs have created a lasting narrative and industry of 'rogue' sharks, rabid dogs, territorial bears, hungry crocodiles, and other animals that intentionally and sometimes hysterically attack innocent people in classic 'Sharknado' style. [Sign up for Today in Science, a free daily newsletter] The public believed this story of intentionality so completely that every shark bite was essentially a murder, and every shark a potential murderer, and the beach was the scene of a crime by a deviant monster against innocent beachgoers. Importantly, the rogue narrative of sharks gaining a taste for human flesh pre-dated Jaws, and was invented largely by an Australian surgeon, Sir Victor Coppleson, in the 1950s. Peter Benchley's 1974 novel, Jaws, and the movie blockbuster provided the justification for, and weakened push-back against, all the anti-shark public policies that followed, including revenge shark hunts, shark derbies, changes to fishery laws that classified sharks as waste fish, delays in enacting shark conservation and the placement of lethal shark nets on some international beaches. Another piece of the Jaws story was its portrayal of an innocent coastal community being preyed upon. Here, beachgoers were not large land animals entering into the foreign domain of a dynamic marine ecosystem, but they were cast as property owners and recreational water users who had the right to expect nature to behave in a domesticated manner. This misperception that the beach is safe introduced as big a misconception and falsehood on the public, as the idea that sharks are all dangerous. The ocean is constantly in flux, and the direct opposite to "shark bites are intentional attacks" is a much less Oscar-worthy story about the beach as a wild, dynamic and active ocean environment. In 2014, I proposed the 'Jaws Effect' in the Australian Journal of Political Science, in which I argue that politicians use familiar fictional films and movies as the basis for explaining real-life events. The Jaws Effect can be seen as a political instrument that uses films to reinforce three themes: 'that sharks are intentionally hunting people, that shark bites are fatal events and that killing individual sharks will solve the problem.' Following a terrible fatal shark bite in Western Australia in 2000 and subsequent shark bites and encounters, the West Australian premier Colin Barnett repeatedly used the term 'rogue sharks' the he said were returning to the beach to attack swimmers, so there needed to be a law to help the government kill specific target sharks that were intent on haunting the local beach community. During this period, Benchley wrote an open letter to Western Australia about the case and the political directive to hunt down the shark responsible. He wrote, 'This was not a rogue shark, tantalised by the taste of human flesh and bound now to kill and kill again. Such creatures do not exist, despite what you might have derived from Jaws.' The Jaws Effect, however, continues in Australia today. In 2024, the District Council of Elliston passed a motion to allow fisheries officers in South Australia to kill great white sharks following shark bites in that area, which stated, 'Sharks are capable of learned behavior. The purpose of terminating the shark responsible for an attack is to prevent that shark from using that behavior to harm another person.' Yet, at 50 years old, Jaws is also a celebration of sharks, creating a fascination that helped lead to more than two generations of new shark researchers. Indeed, some of the people who have done the most for shark conservation worked on Jaws. Valerie Taylor help collect footage of sharks that was used in Jaws and was one of the leaders in New South Wales on conservation laws to protect the Grey Nurse Shark, which in 1984 became the first protected species of shark. As well, Leonard Compagno, who was a scientist and consultant on Jaws, also led the effort to protect White Sharks in South Africa. The idea that Jaws led to bad public relations is too simple a story. Our reading of the movie, real-life sharks, the public and our beaches are all evolving. Jaws is better at 50, sharks are seen more positively in 2025, and the public is more engaged in shark conservation and beach safety. There's even a 'Jawsie' Award in Australia, given yearly to the most outlandish reports of shark attacks and meant to spur real beach safety awareness. I would be remiss if I did not note the connection between Jaws, the false rogue shark theory, and current debate over orcas ramming into yachts off the Strait of Gibraltar. Both National Geographic and the BBC, for example, have run headlines about such 'rogue' orcas. In the mix of stories to explain this behavior, one that claimed that it was an 'orca scorned' type situation where a female orca had been traumatized by a boat previously and was now training her young to attack boats in revenge. Very Jaws, or perhaps Jaws 3, but there will be no awards for this fish story. This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.
Yahoo
24-05-2025
- Science
- Yahoo
New Infrared Contacts Let You See in the Dark
Humans have a new way of seeing infrared light, without the need for clunky night-vision goggles. Researchers have made the first contact lenses to convey infrared vision — and the devices work even when people have their eyes closed. The team behind the invention, led by scientists at the University of Science and Technology of China (USTC) in Hefei, gave the lenses their power by infusing them with nanoparticles that convert near-infrared light in the 800–1,600-nanometre range into shorter-wavelength, visible light that humans can see, in the 400–700-nanometre range. The researchers estimate that the lenses cost around US$200 per pair to make. The technology, which was detailed in Cell on 22 May, 'is incredibly cool, just like something out of a science-fiction movie', says Xiaomin Li, a chemist at Fudan University in Shanghai, China. It opens up 'new possibilities for understanding the world around us', he adds. [Sign up for Today in Science, a free daily newsletter] Near-infrared light sits just outside the range of wavelengths that humans can normally detect. Some animals can sense infrared light, although probably not well enough to form images. Night-vision goggles enable humans to see infrared radiation, but they are bulky and require a power source to work. The new lenses avoid these limitations while also offering richer, multi-coloured infrared images that night-vision goggles, which operate on a monochrome green scale, typically do not. However, the lenses do have their own shortcomings. Because the embedded nanoparticles scatter light, the images the lenses create are blurry. The team partially corrected this by putting the technology into glasses with additional lenses that redirect the light. Moreover, unlike night-vision goggles, which amplify light to detect low-level infrared signals, the lenses allow users to see only intense infrared signals, such as those emitted by light-emitting diodes (LEDs). For these reasons, some critics don't think the lenses will prove useful. 'I cannot think of any application that would not be fundamentally simpler with infrared goggles,' says Glen Jeffery, a neuroscientist at University College London who specializes in eye health. 'Evolution has avoided this for a good reason.' Nevertheless, the authors think that their lenses can be further optimized and foresee several possible uses for the invention. For instance, wearers would be able to read anti-counterfeit marks that emit infrared wavelengths but are otherwise invisible to the human eye, says co-author Yuqian Ma, a neuroscientist at the USTC. Li, who was not involved in the work, offers another possibility: the lenses might be worn by doctors conducting near-infrared fluorescence surgery, to directly detect and remove cancerous lesions 'without relying on bulky traditional equipment'. To create the contact lenses, the scientists built on previous research in which they gave mice infrared vision by injecting nanoparticles into the animals' retinas. This time, they took a less invasive approach and added nanoparticles made of rare-earth metals including ytterbium and erbium to a soup of polymer building blocks to form the soft lenses, and then tested them for safety. The main challenge, Ma says, was to pack enough nanoparticles into the lenses to convert sufficient infrared light into detectable visible light, while not otherwise altering the lenses' optical properties, including their transparency. Tests in mice showed that animals wearing the lenses tended to choose a dark box that was considered 'safe' over one lit up by infrared light, whereas mice without the lenses showed no preference for either box. Humans wearing the lenses could see flickering infrared light from an LED well enough to both pick up Morse code signals and sense which direction the signals were coming from. The lenses' performance even improved when participants closed their eyes, because near-infrared light easily penetrates the eyelids, whereas visible light, which could have interfered with image formation, does so to a lesser degree. 'Witnessing people wearing contact lenses and successfully seeing infrared flashes was undoubtedly an exhilarating moment,' Ma says. The team now plans to find ways to cram more nanoparticles into the lenses and hopes to develop particles that can convert light with higher efficiency, to improve the technology's sensitivity. 'We have overcome the physiological limitations of human vision, as if opening a brand-new window onto the world,' Ma says. This article is reproduced with permission and was first published on May 22, 2025.
Yahoo
23-05-2025
- Science
- Yahoo
Hypervelocity Stars Hint at a Nearby Supermassive Black Hole
An astonishing fact only known for the past few decades is that every big galaxy in the universe has a supermassive black hole at its heart. This was suspected in the 1980s, and observations from the Hubble Space Telescope, which has peered deep into the cores of galaxies all across the sky, confirmed it. The 'normal' kinds of black holes made when stars explode range from five to about 100 times the mass of the sun, more or less. But these central galactic monsters are millions of times more massive, and some have grown to the Brobdingnagian heft of billions of solar masses. A lot of mysteries still remain, of course, such as how they formed early in the history of the universe, how they grew so humongous so fast and what role they played in their host galaxy's formation. But one odd question still nagging at astronomers is: What's the galaxy size cutoff where this trend stops? In other words, is there some lower limit to how massive a galaxy can be and still harbor one of these beasts? The inklings of an answer are emerging from a surprising place: studies of rare stars moving through our own galaxy at truly ludicrous speeds. [Sign up for Today in Science, a free daily newsletter] Orbiting our Milky Way galaxy is a menagerie of smaller 'dwarf' galaxies, some so tiny and faint you need huge telescopes to see them at all. But two are so large and close that they're visible to the unaided eye from the Southern Hemisphere: the Large and Small Magellanic Clouds. The Large Magellanic Cloud (LMC) is the bigger and closer of the two, and it's not clear if it harbors a supermassive black hole (SMBH). If such an SMBH exists there, it must be quiescent, meaning it's not actively feeding on matter. As material falls toward such a black hole, it forms a swirling disk of superheated plasma that can glow so brightly it outshines all the stars in the galaxy combined. No such fierce luminescence is seen in the LMC, so we don't know if an SMBH is there and not actively feeding or if the LMC is simply SMBH-free. But a recent study published in the Astrophysical Journal offers strong evidence that an SMBH does lie at the center of the LMC—based on measurements of stellar motions in our own Milky Way! The study looked at hypervelocity stars, ones that are screaming through space at speeds far higher than stars around them. Some of these stars are moving so rapidly that they have reached galactic escape velocity; the Milky Way's gravity can't hold them. In the coming eons, they'll flee the galaxy entirely. And we have good reason to believe these runaway stars were launched by SMBHs—but how? Such a situation starts with a binary system, two stars orbiting each other. These systems contain a substantial amount of orbital energy, the sum of the kinetic energy of the two stars—their energy of motion—and their gravitational potential energy, the amount of energy released if they were to move closer together. If the binary star approaches a third object, some of that energy can be swapped around. One star can become bound to the third object, for example, while the other star can get a kick in its kinetic energy, flinging it away. The amount of the kick depends in part on the gravity of the third object. A massive black hole, of course, has an incredibly strong gravitational field that can fling the star away at high speed. And I do mean high speed; such a star can be flung away from the black hole at a velocity greater than 1,000 kilometers per second. S5-HVS1, for example, was the first confirmed such hypervelocity star, and it's moving at more than 1,700 kilometers per second. Feel free to take a moment to absorb that fact: an entire star has been ejected away from a black hole at more than six million kilometers per hour. The energies involved are terrifying. We have seen a few of these stars in our galaxy, and careful measurements suggest they're moving away from the center of the Milky Way, which is pretty convincing evidence that Sagittarius A*, our own Milky Way's SMBH, is to blame. But not all of the high-velocity stars that have been detected appear to come from our galactic center. Fortunately, Gaia, the sadly now decommissioned European Space Agency astronomical observatory, was designed to obtain extremely accurate measurements of the positions, distances, colors and other characteristics of well more than a billion stars—including their velocity. There are 21 known hypervelocity stars at the outskirts of the Milky Way. Using the phenomenally high-precision Gaia measurements, the astronomers behind the new research examined the stars' 3D velocities through space. They found that five of them have ambiguous origins, while two definitely come from the Milky Way center. Of the 14 still left, three clearly come from the direction of the LMC. The trajectories of these stars effectively point back to their origin, and based on our current knowledge, that origin must be a supermassive black hole. Even better, although the remaining 11 stars have trajectories that are consistent with both Milky Way and LMC origins, the researchers found that five are more likely to have come from our home galaxy and the other six are more likely to have come from the LMC. So there could be nine known hypervelocity stars plunging through our galaxy that were ejected by a supermassive black hole in another galaxy. Using some sophisticated math, the team found that the most likely mass of the black hole is 600,000 or so times the mass of the sun. This isn't huge for an SMBH—it's very much on the low end of the scale, in fact—but then, the LMC is a small galaxy, only 1 percent or so the mass of the Milky Way. We know that the mass of a black hole tends to scale with its host galaxy's mass (because they form together and affect each other's growth), so this lower mass is consistent with that. If this is true, then our satellite galaxy is shooting stars at us! And there may be more of them yet to be found, hurtling through space unseen on the other side of our galaxy, or so far out that they're difficult to spot and even harder to study. And all this helps us get a clearer—but still quite hazy!—sense of just how far down the galactic scale we can expect to find big black holes. Black holes are funny. Most people would worry about falling into one, as well as a host of other terrors, but now you can add 'having to dodge intergalactic stellar bullets' to that list.
