After decades of searching for extraterrestrial intelligence, the nonprofit SETI Foundation has an announcement. "A new study by researchers at the SETI Institute suggests stellar 'space weather' could make radio signals from extraterrestrial intelligence harder to detect." Stellar activity and plasma turbulence near a transmitting planet can broaden an otherwise ultra-narrow signal, spreading its power across more frequencies and making it more difficult to detect in traditional narrowband searches. For decades, many SETI experiments have focused on identifying spikes in frequency — signals unlikely to be produced by natural astrophysical processes. But the new research highlights an overlooked complication: even if an extraterrestrial transmitter produces a perfectly narrow signal, it may not remain narrow by the time it leaves its home system... "If a signal gets broadened by its own star's environment, it can slip below our detection thresholds, even if it's there, potentially helping explain some of the radio silence we've seen in technosignature searches," said Dr. Vishal Gajjar, Astronomer at the SETI Institute and lead author of the paper. The researchers created "a practical framework for estimating how much broadening could occur for different types of stars" — and accounting for space weather — by "using radio transmissions from spacecraft in our own solar system, then extrapolated to other stellar environments." The study's co-author (a SETI Institute research assistant) suggests this coud lead to better-targetted SETI searches. (M-dwarf stars — about 75% of stars in the Milky Way — actually have the highest likelihood that narrowband signals would get broadened before leaving their system...)

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Colliding black holes were detected through spacetime ripples for the first time in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO), notes Space.com: Since then, LIGO and its partner gravitational wave detectors Virgo in Italy and KAGRA (Kamioka Gravitational Wave Detector) in Japan have detected a multitude of gravitational waves from colliding black holes, merging neutron stars, and even the odd "mixed merger" between a black hole and a neutron star... During the first three observing runs of LIGO, Virgo and KAGRA, scientists had only "heard" 90 potential gravitational wave sources. But now they've published new data from the LIGO-Virgo-KAGRA (LVK) Collaboration that includes 128 more gravitatational wave sources — some incredibly distant: [Gravitational-Wave Transient Catalog-4.0, or GWTC-4] was collected during the fourth observational run of these gravitational wave detectors, which was conducted between May 2023 and Jan. 2024... Excitingly, GWTC-4 could technically have been even larger, as around 170 other gravitational wave detections made by LIGO, Virgo and KAGRA haven't yet made their way into the catalog. One aspect of GWTC-4 that really stands out is the variety of events that created these signals. Within this catalog are gravitational waves from mergers between the heaviest black hole binaries yet, each about 130 times as massive as the sun, lopsided mergers between black holes with seriously mismatched masses, and black holes that are spinning at incredible speeds of around 40% the speed of light. In these cases, scientists think the extreme characteristics of the black holes involved in these mergers are the result of prior collisions, providing evidence of merger chains that explain how some black holes grow to masses billions of times that of the sun... GWTC-4 also includes two new mixed mergers involving black holes and neutron stars. [LVK member Daniel Williams, of the University of Glasgow in the U.K., said in their statement] "We are really pushing the edges, and are seeing things that are more massive, spinning faster, and are more astrophysically interesting and unusual." The catalog also demonstrates just how sensitive the LVK detectors have become. Some of the neutron star mergers occurred up to 1 billion light-years away, while some of the black hole mergers occurred up to 10 billion light-years away. Einstein's theory of general relativity can be tested with these detections, and "So far, the theory is passing all our tests," says LVK member Aaron Zimmerman, of the University of Texas at Austin. "But we're also learning that we have to make even more accurate predictions to keep up with all the data the universe is giving us." And LVK member Rachel Gray, a lecturer at the University of Glasgow, says "every merging black hole gives us a measurement of the Hubble constant, and by combining all of the gravitational wave sources together, we can vastly improve how accurate this measurement is." In short, says LVK member Lucy Thomas of the California Institute of Technology (Caltech), "Each new gravitational-wave detection allows us to unlock another piece of the universe's puzzle in ways we couldn't just a decade ago."

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Astronomers have spotted a galaxy they believe is made of 99.9% dark matter, reports CNN — and it's so faint, it's almost invisible: CDG-2, which is about 300 million light-years from Earth, appears to be so rich in dark matter that it could belong to a hypothesized subset of low surface brightness galaxies called "dark galaxies," which are believed to contain few or no stars.... [Post-doctoral astrophysics/statistics fellow Dayi Li at the University of Toronto was lead author on a study about the discovery, and tells CNN] There is no strict definition of dark galaxies... but their existence is predicted by dark matter theories and cosmological simulations. "Where exactly do we draw the line in terms of how many stars they should have is still ambiguous, because not everything in astronomy is as clear-cut as we like," he said. "To be technically correct, CDG-2 is an almost-dark galaxy. But the importance of CDG-2 is that it nudges us much closer to getting to that truly dark regime, while previously we did not think a galaxy this faint could exist." To observe CDG-2, the researchers used data from three telescopes — Hubble, the European Space Agency's Euclid space observatory and the Subaru Telescope in Hawaii — along with a novel approach that involved looking for objects called globular clusters. "These are very tight, spherical groupings of very olds stars, basically the relics of the first generation of star formation," Li said. Globular clusters are bright even if the surrounding galaxy is not, and previous observations have shown a relationship between them and the presence of dark matter in a galaxy, Li added. Because CDG-2 appears to have very few stars, there must be something else providing the mass that the clusters need to hold themselves together. Li and his colleagues assume that the source of the mass is dark matter. The researchers found a set of four globular clusters in the Perseus Cluster, a group of thousands of galaxies immersed in a cloud of gas and one of the most massive objects in the universe. Further observations revealed a glow or halo around the globular clusters, suggesting the presence of a galaxy... Astronomers believe, Li explained, that after the formation of the clusters early in the galaxy's existence, larger surrounding galaxies stripped it of the hydrogen gas required to make more individual stars like our sun. "The material that this galaxy needed to continue to form stars was no longer there, so it was left with basically just a dark matter halo and the four globular clusters." The process, he added, would leave behind a skeleton or ghost of "a galaxy that pretty much just failed." As a result of this formation mechanism, the galaxy only has 0.005% of the brightness of our own galaxy, Li said... Studying potential dark galaxies is important because they provide nearly pristine views of the behavior of dark matter, according to Neal Dalal, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, who was not involved with the study. Robert Minchin, an astronomer at New Mexico's National Radio Astronomy Observatory, told CNN that "it seems likely that other very dark galaxies will be found by this method in the future."

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NASA is eyeing an April launch window for the upcoming Artemis II mission after it repaired a helium-flow issue on the Space Launch System upper stage rocket. "Work on the rocket and spacecraft will continue in the coming weeks as NASA prepares for rolling the rocket out to the launch pad again later this month ahead of a potential launch in April," NASA wrote in an update on Tuesday. Space.com reports: The repair work occurred inside the huge Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center (KSC) in Florida. Artemis 2's SLS and Orion crew capsule have been in the VAB since Feb. 25, when they rolled back to the hangar from KSC's Launch Pad 39B. Just a few days earlier, the Artemis 2 stack successfully completed a wet dress rehearsal, a two-day-long practice run of the procedures leading up to launch. In the wake of that test, however, NASA noticed an interruption in helium flow in the SLS' upper stage. That was a significant issue, because helium pressurizes the rocket's propellant tanks. Rollback was the only option, as the affected area in the upper stage was not accessible at the pad. The problem took a potential March launch out of play for Artemis 2, which will send four astronauts on a roughly 10-day flight around the moon. It will be the first crewed flight to the lunar neighborhood since Apollo 17 in 1972. The next Artemis 2 launch window opens in April, with liftoff opportunities on April 1, April 3-6 and April 30. And those options apparently remain in play, thanks to recent work in the VAB. That work centered on a seal in an interface through which helium flows from ground equipment into the SLS upper stage. That seal was obstructing the interface, which is known as a quick disconnect.

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"Saturn and some of its 274 moons are pretty weird," writes Smithsonian magazine: [Saturn moon] Titan has strangely few impact craters, Hyperion is tiny and misshapen, and Iapetus has a tilted orbit. What's more, planets tend to wobble along their rotational axes as they spin, like an off-kilter spinning top in the moments before it topples over. Formally called precession, scientists have long thought that Saturn's wobble rate should match Neptune's because they're probably gravitationally linked. However, data from NASA's Cassini spacecraft, which studied the ringed planet from 2004 to 2017, revealed that Saturn's precession rate is slightly speedier than Neptune's. In 2022, some researchers suggested that the destruction of a hypothetical moon, called Chrysalis, around 160 million years ago may have knocked Saturn out of sync and formed the pieces that became the planet's rings. But this work implied that Chrysalis probably would've crashed into Titan, posing a major problem, study co-author Matija Äuk, an astronomer at the SETI Institute, tells New Scientist's Leah Crane. In that case, Chrysalis' debris couldn't have become the rings, he says. So, Äuk and his colleagues used computer simulations to investigate what would happen if Chrysalis did smack into Titan. If that happened around 400 million years ago, they found, the crash would've wiped away Titan's craters and made its orbit more elliptical. The altered path may have slowly pushed the trajectories of other moons, which then scraped against one another and left chunks of ice and rock that now make up Saturn's rings. The timing seems to align with the rings' estimated age of roughly 100 million years. Additionally, one piece of kicked-up debris may have formed the weird moon Hyperion, which may have subsequently tilted the orbit of the moon Iapetus, according to the analysis. The scenario could also resolve Saturn's unexpected wobble, which is currently "a little bit too fast," Äuk tells Jacopo Prisco at CNN. The study has been accepted for publication in the Planetary Science Journal, and is already available on the preprint server arXiv.

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A start-up called Reflect Orbital "proposes to use large, mirrored satellites to redirect sunlight to Earth at night," reports the Washington Post, "with plans to bathe solar farms, industrial sites and even entire cities in light that could, if desired, reach the intensity of daylight...." Slashdot noted their idea in 2022 — but Reflect Orbital now expects to launch its first satellite in April, according to the article. "But its grand vision is largely 'aspirational,' as its young founder, Ben Nowack, told me..." Reflect Orbital's Nowack describes a scene right out of sci-fi: An extremely bright star appears on the northern horizon and makes its way across the sky, illuminating a 5-kilometer circle on Earth, then setting on the southern horizon about five minutes later, just as another such "star" appears in the north. To make the night even brighter, a customer could make 10 "stars" appear at once in the north by ordering them on an app. Two such artificial stars are in development in Reflect Orbital's factory. Nowack showed them to me on a Zoom call. The first to launch is 50 feet across, but he plans later to build them three times that size. If all goes according to plan, he'll have 50,000 of them circling the Earth in 2035 at an altitude of around 400 miles. Nowack plans to start selling the service "in mostly developing nations or places that don't have streetlights yet." Eventually, he thinks, he can illuminate major cities, turn solar fields and farms into round-the-clock operations for any business or municipality that pays for it. He likened his technology to the invention of crop irrigation thousands of years ago. "I see this as much the same thing," he said, arguing that people would no longer have to "wait for the sun to shine." The article adds that Elon Musk's SpaceX "wants to launch as many as a million satellites to serve as orbiting data centers — 70 times the number of satellites now in orbit." (America's satellite-regulation Federal Communications Commission grants a "categorical exclusion" from environmental review to satellites on the grounds that their operations "normally do not have significant effects on the human environment.") The public comment periods for the two proposals close on March 6 and March 9.

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A start-up called Reflect Orbital "proposes to use large, mirrored satellites to redirect sunlight to Earth at night," reports the Washington Post, "with plans to bathe solar farms, industrial sites and even entire cities in light that could, if desired, reach the intensity of daylight...." Slashdot noted their idea in 2022 — but Reflect Orbital now expects to launch its first satellite in April, according to the article. "But its grand vision is largely 'aspirational,' as its young founder, Ben Nowack, told me..." Reflect Orbital's Nowack describes a scene right out of sci-fi: An extremely bright star appears on the northern horizon and makes its way across the sky, illuminating a 5-kilometer circle on Earth, then setting on the southern horizon about five minutes later, just as another such "star" appears in the north. To make the night even brighter, a customer could make 10 "stars" appear at once in the north by ordering them on an app. Two such artificial stars are in development in Reflect Orbital's factory. Nowack showed them to me on a Zoom call. The first to launch is 50 feet across, but he plans later to build them three times that size. If all goes according to plan, he'll have 50,000 of them circling the Earth in 2035 at an altitude of around 400 miles. Nowack plans to start selling the service "in mostly developing nations or places that don't have streetlights yet." Eventually, he thinks, he can illuminate major cities, turn solar fields and farms into round-the-clock operations for any business or municipality that pays for it. He likened his technology to the invention of crop irrigation thousands of years ago. "I see this as much the same thing," he said, arguing that people would no longer have to "wait for the sun to shine." The article adds that Elon Musk's SpaceX "wants to launch as many as a million satellites to serve as orbiting data centers — 70 times the number of satellites now in orbit." (America's satellite-regulation Federal Communications Commission grants a "categorical exclusion" from environmental review to satellites on the grounds that their operations "normally do not have significant effects on the human environment.") The public comment periods for the two proposals close on March 6 and March 9.

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On February 24th, the Vera C. Rubin Observatory activated its automated alert system, sending out roughly 800,000 real-time notifications flagging asteroids, supernovae, flaring black holes and "other transient celestial events," reports Scientific American. And this is only the beginning -- that number is projected to climb into the millions as it continues scanning the ever-changing sky. From the report: The astronomical observatory equipped with world's largest camera hit a key milestone on February 24, when a complex data-processing system pushed hundreds of thousands of alerts out to scientists eager to pore over its most exciting sightings. The Vera C. Rubin Observatory began operations last year, capturing stunning, panoramic time-lapse views of the cosmos with ease. Rubin's first images, based on just 10 hours of observations, let space fans zoom seemingly forever into an overwhelmingly starry sky. But watchful astronomers were always awaiting the next step: the system that would automatically alert them to the most promising activity in the overhead sky amid the 1,000 or so enormous images that Rubin's telescope captures every night. "We can detect everything that changes, moves and appears," said Yusra AlSayyad, an astronomer at Princeton University and Rubin's deputy associate director for data management, to Scientific American last summer. "It's way too much for one person to manually sift through and filter and monitor themselves." So even as they were designing and building the Rubin Observatory itself, scientists were also designing an alert system to help astronomers navigate the flood of data. As soon as the telescope began observations, the team started constructing a static reference image of the entire sky in impeccable detail. Now the data processing systems that support the observatory are starting to automatically compare every new Rubin image to the corresponding section of that background template. The systems identify all of the differences, each of which is individually flagged. The algorithms can also distinguish between a potential supernova and a possible newfound asteroid, for example. Alerting the scientific community is the final, crucial step. Astronomers -- as well as members of the public -- can sign up for notifications based on the type of sighting they're interested in and the brightness of the observation in question. And now that the alerts system has gone live, users receive a tiny, fuzzy image with some astronomical metadata of each observation that fits their criteria -- all just a couple of minutes after Rubin captures the original image.

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"A surprisingly ravenous black hole from the dawn of the universe is breaking two big rules," reports Live Science. "It's not only exceeding the 'speed limit' of black hole growth but also generating extreme X-ray and radio wave emissions — two features that are not predicted to coexist..." "How is this rule-breaking behavior even possible? In a paper published Jan. 21 in The Astrophysical Journal, an international team of researchers observed ID830 in multiple wavelengths to find an answer...." As they attract gas and dust, this material accumulates in a swirling accretion disk. Gravity pulls the material from the disk into the black hole, but the infalling material generates radiation pressure that pushes outward and prevents more stuff from falling in. As a result, black holes are muzzled by a self-regulating process called the Eddington limit... Its X-ray brightness suggests that ID830 is accreting mass at about 13 times the Eddington limit, due to a sudden burst of inflowing gas that may have occurred as ID830 shredded and engulfed a celestial body that wandered too close. "For a supermassive black hole (SMBH) as massive as ID830, this would require not a normal (main-sequence) star, but a more massive giant star or a huge gas cloud," study co-author Sakiko Obuchi, an observational astronomer at Waseda University in Tokyo, told Live Science via email. Such super-Eddington phases may be incredibly brief, as "this transitional phase is expected to last for roughly 300 years," Obuchi added. ID830 also simultaneously displays radio and X-ray emissions. These two features are not expected to coexist, especially because super-Eddington accretion is thought to suppress such emissions. "This unexpected combination hints at physical mechanisms not yet fully captured by current models of extreme accretion and jet launching," the researchers said in a statement. So while ID830 is launching massive radio jets, its X-ray emissions appear to originate from a structure called a corona, produced as intense magnetic fields from the accretion disk create a thin but turbulent billion-degree cloud of turbocharged particles. These particles orbit the black hole at nearly the speed of light, in what NASA calls "one of the most extreme physical environments in the universe." Altogether, ID830's rule-breaking behaviors suggest that it is in a rare transitional phase of excessive consumption — and excretion. This incredible feeding burst has energized both its jets and its corona, making ID830 shine brightly across multiple wavelengths as it spews out excess radiation. Additionally, based on UV-brightness analysis, quasars like ID830 may be unexpectedly common, the researchers said. Models predict that only around 10% of quasars have spectacular radio jets, but these energetic objects could be significantly more abundant in the early universe than previously suggested. Most importantly, ID830 also shows how SMBHs can regulate galaxy growth in the early universe. As a black hole gobbles matter at the super-Eddington limit, the energy from its resultant emissions can heat and disperse matter throughout the interstellar medium — the gas between stars — to suppress star formation. As a result, ancient SMBHs like ID830 may have grown massive at the expense of their host galaxies.

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Two astrophysicists at Spain's Instituto de Astrofísica de Canarias analyzed data from the James Webb Space Telescope — the most powerful telescope available — on 31 galaxies with an average redshift of 7.3 (when the universe was 700 million years old, according to the standard model). "We found that they are on average ~600 million years old old, according to the comparison with theoretical models based on previous knowledge of nearby galaxies..." "If this result is correct, we would have to think about how it is possible that these massive and luminous galaxies were formed and started to produce stars in a short time. It is a challenge." But "The fact that some of these galaxies might be older than the universe, within some significant confidence level, is even more challenging." The most extreme case is for the galaxy JADES-1050323 with redshift 6.9, which has, according to my calculation, an age incompatible to be younger than the age of the universe (800 million years) within 4.7-sigma (that is, a probability that this happens by chance as statistical fluctuation of one in one million). If this result is confirmed, it would invalidate the standard Lambda-CDM cosmological model. Certainly, such an extraordinary change of paradigm would require further corroboration and other stronger evidence. Anyway, it would be interesting for other researchers to try to explain the Spectral Energy Distribution of JADES-1050323 in standard terms, if they can ... and without introducing unrealistic/impossible models of extinction, as is usually done. The findings are published in the journal Monthly Notices of the Royal Astronomical Society.

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Elon Musk told podcast host Dwarkesh Patel and Stripe co-founder John Collison that space will become the most economically compelling location for AI data centers in less than 36 months, a prediction rooted not in some exotic technical breakthrough but in the basic math of electricity supply: chip output is growing exponentially, and electrical output outside China is essentially flat. Solar panels in orbit generate roughly five times the power they do on the ground because there is no day-night cycle, no cloud cover, no atmospheric loss, and no atmosphere-related energy reduction. The system economics are even more favorable because space-based operations eliminate the need for batteries entirely, making the effective cost roughly 10 times cheaper than terrestrial solar, Musk said. The terrestrial bottleneck is already real. Musk said powering 330,000 Nvidia GB300 chips -- once you account for networking hardware, storage, peak cooling on the hottest day of the year, and reserve margin for generator servicing -- requires roughly a gigawatt at the generation level. Gas turbines are sold out through 2030, and the limiting factor is the casting of turbine vanes and blades, a process handled by just three companies worldwide. Five years from now, Musk predicted, SpaceX will launch and operate more AI compute annually than the cumulative total on Earth, expecting at least a few hundred gigawatts per year in space. Patel estimated that 100 gigawatts alone would require on the order of 10,000 Starship launches per year, a figure Musk affirmed. SpaceX is gearing up for 10,000 launches a year, Musk said, and possibly 20,000 to 30,000.

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European security officials believe two Russian space vehicles have intercepted the communications of at least a dozen key satellites over the continent. From a report: Officials believe that the likely interceptions, which have not previously been reported, risk not only compromising sensitive information transmitted by the satellites but could also allow Moscow to manipulate their trajectories or even crash them. Russian space vehicles have shadowed European satellites more intensively over the past three years, at a time of high tension between the Kremlin and the West following Moscow's full-scale invasion of Ukraine. For several years, military and civilian space authorities in the West have been tracking the activities of Luch-1 and Luch-2 -- two Russian objects that have carried out repeated suspicious maneuvers in orbit. Both vehicles have made risky close approaches to some of Europe's most important geostationary satellites, which operate high above the Earth and service the continent, including the UK, as well as large parts of Africa and the Middle East. According to orbital data and ground-based telescopic observations, they have lingered nearby for weeks at a time, particularly over the past three years. Since its launch in 2023, Luch-2 has approached 17 European satellites.

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