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Yahoo
12 hours ago
- Science
- Yahoo
Satellite streaks: Can the huge new Vera Rubin Observatory function in the megaconstellation age?
When you buy through links on our articles, Future and its syndication partners may earn a commission. When astronomers first dreamt up the Vera Rubin Observatory in the 1990s, the sky above the Chilean Cerro Pachón, where the star-observing machine was to be located, looked different than it does today. Dotted with millions of stars, galaxies and nebulas, it was only occasionally crossed by a lone satellite. Then, just a few years before the observatory's expected inauguration, the era of megaconstellations took off, and astronomers found themselves racing to find ways to protect the telescope's images from satellite contamination. They didn't have much time. When construction of the $680 million observatory began in 2015, everything was still going according to plan. Four years later, SpaceX launched the first batch of Starlink internet satellites, Starlink trains became a thing, and astronomers realized that the satellites, orbiting only 340 miles (550 kilometers) above Earth, were too bright not to interfere with their observations. Vera Rubin, due to its wide field of view and exceptional sensitivity, was to feel their presence especially keenly. "All of the characteristics that make Vera Rubin Observatory so amazing for surveying the whole southern sky also mean it's going to see a whole bunch of these satellites," Meredith Rawls, a research scientist for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) and an astronomer at the University of Washington, told The Vera Rubin telescope, which is set to open its eyes to the sky later this month, has a 26-foot-wide (8.4 meters) mirror, one of the largest in the world. It's also fitted with the largest camera ever built for an astronomical telescope — a 5.4-foot-wide (1.65 m), 3,200-megapixel device with 189 CCD detectors. The telescope will be able to tilt its mirror to change its view of the sky every night in order to complete a whole sky survey every three days. In each sweep of the celestial dome, the telescope will not only capture the myriads of stars and distant galaxies invisible to the human eye, but also the thousands of satellites that are millions of times brighter than those precious astronomical targets. And this problem will only get worse with time. SpaceX was initially talking about a constellation of 12,000 satellites but now plans a fleet of 42,000 spacecraft. Other broadband operations — like Amazon's Kuiper network and the Chinese projects Guowang, Qianfan, and Geespace — intend to launch tens of thousands of satellites of their own. Currently, about 10,000 satellites orbit Earth, but the number could increase to 100,000 in the next decade if all those plans come to fruition. "It's unfortunate that this huge increase [in the number of satellites] is coinciding with the decade of Vera Rubin's operation," said Rawls. "It's existentially frustrating that we are putting a bunch of stuff in orbit that is interfering with our views of the cosmos." Rawls has worked on the Vera Rubin Observatory project since 2016, initially developing image processing algorithms to filter out faults of the camera's sensors and detecting unexpected celestial phenomena such as supernova explosions. The arrival of Starlink and its counterparts forced her to refocus. Today, she develops techniques to flag the presence of satellites in images and distinguish them from objects of astronomical interest, including passing asteroids. Still, Rawls said that the satellite streak problem is not a death threat for Vera Rubin's science mission. She describes the satellite streaks more like "bugs on a windshield" on a summer night, obscuring the view at times, but not completely ruining it. "It's true that a large fraction of exposures is going to contain a satellite streak, but the field of view is big, and so the number of actual pixels that are affected is very small," said Rawls. "At most, [the satellite streaks] are a few hundred pixels wide. But a single detector has 4,000 pixels, and the camera has 189 CCD detectors tracking the sky." Noelia Noël, a professor of astrophysics at the University of Surrey in the U.K., told that up to 40% of the images captured by the Vera Rubin telescope over its 10-year mission are expected to have streaks in them. "If you take 10 million images, over 4 million of them could be degraded," said Noël, who is also part of Vera Rubin's LSST project. "This is a huge waste of taxpayers' money. One night of Vera Rubin's observations costs something like £60,000 [about $81,000]. So, if you ruin the images, it's your money going to waste." Apart from outshining legitimate objects of interest, the satellites could also be mistaken for real celestial phenomena. In 2021, for example, a group of scientists thought that a star exploded in the oldest known galaxy when they observed a sudden brightening in images taken by the Keck Telescope in Hawaii. It later turned out that, as the astronomers pointed their instrument at the galaxy, a piece of debris passed in front of their field of few, reflecting sunlight. "We don't want to give people a catalog of data where each pixel is supposed to be an actual star, and then surprise, a third of them are just bright detections where it happened to be in the satellite trail," said Rawls. The algorithms developed by Rawls and her colleagues will use a stacking method to compare multiple images of the same portion of the sky to spot outliers and flag them. If a bright object appears in one image and disappears in the next, it's more likely a passing satellite than a stellar explosion or dimming, said Rawls. Megaconstellations like Starlink are only one part of the problem. In 2022, the American company AST SpaceMobile began deploying a constellation of its BlueBird satellites — essentially giant antenna arrays, each one covering 693 square feet (64 square meters). The satellites are intended to provide 5G via satellite directly to smartphone users on Earth, but they are also insanely bright. They are so bright, in fact, that the Vera Rubin Telescope must plan for their passes in advance in order to avoid them, according to Rawls. "It would be a waste of 30 seconds looking at that portion of the sky with that super bright thing going through," said Rawls. "Thankfully, there are not that many of these super big, super bright satellites yet. But I worry that might change in the coming years." How much of Vera Rubin's precious sky views will be obscured by passing satellites and how much science will be lost as a result remains to be seen. Rawls hopes that attempts to darken satellites, already trialled by SpaceX with limited effects, will eventually succeed, reducing the light contamination to a minimum. Related Stories: — How Earth's new Rubin Observatory will usher in the next era of asteroid space missions — Blinded by the light: How bad are satellite megaconstellations for astronomy? — Megaconstellations could destroy astronomy, and there's no easy fix The International Astronomical Union (IAU) has previously called on satellite makers to strive to make their satellites invisible to the naked eye — an equivalent of magnitude 7 on the scale used to measure the brightness of celestial objects. The magnitude scale is inverse to the actual brightness and logarithmic, meaning that each subsequent grade is 2.5 times dimmer than the previous one. So far, Starlink satellites score between magnitudes 3 and 5. "If satellite operators were able to keep their hardware within approximately the IAU brightness limit, then the impact on ground-based astronomy would be minimal," said Rawls. "In practice, that's not happening, because it's really hard to make stuff that dark." Some glimpses of hope may be appearing on the horizon, however. U.K.-based company Surrey NanoSystems has recently introduced a new type of space paint that is easy to apply, resistant against the harsh space environment and reflects so little light that it could reach the needed brightness reduction. It may be ready just in time.
Yahoo
11-06-2025
- Science
- Yahoo
Who was Vera Rubin? Here's what to know about the astronomer behind dark matter.
Vera Rubin had just finished her ice cream when she saw something that would change astronomy forever. It was long past midnight one early morning in the 1960s, and Rubin and her colleague Kent Ford were at Kitt Peak National Observatory in the middle of the Arizona desert. That night they were tracking how hot gas from young stars circled Andromeda, the Milky Way's galactic neighbor. Rubin and Ford would trade off recording the gases' chemical fingerprints or processing photographic plates. While waiting for the plates to develop, Rubin would eat an ice cream cone. Four cones in, Rubin could draw Andromeda's rotation curve—she could plot the distance of gas clouds on an X-axis and their speeds on the Y-axis. At the time, astronomers assumed the stars circling a galaxy would act like the planets circling the sun in our solar system. Stars closer to the galaxy's center would circle quickly, while stars farther out would orbit slowly because core's gravitational pull was weaker out there. The curve, then, should start high and fall the farther the distance from a galaxy's center, astronomers assumed. Rubin never liked assumptions. She'd rather collect data, even if it met expectations. But what Rubin saw in that rotation curve didn't. The close-in and far-out stars seemed to be circling Andromeda at roughly the same speeds. The curve was flat. The ice-cream fueled find, and those that followed, forced astronomers to rethink not only what we know about galaxies but also what we know about the universe. It forced them to reimagine the fabric of the cosmos. They'd ultimately conclude that that fabric included a mysterious substance, an invisible form of matter now known as dark matter, that to this day we don't fully understand. But it wasn't just this Copernican-esque discovery of flat rotation curves that made Rubin a legend. It was the way she discovered it, the way she advocated for equality in astronomy, the way she welcomed new astronomers into the field without hesitation and kept going to the telescope well into her eighties, which is when I got to know her. It was November 2007 when I joined Rubin at Kitt Peak. No photographic plates. No winter ice cream. Just a veteran astronomer, a cub reporter, and a spiral galaxy to observe. It was in her reminiscing during those nights that I came to understand that her dark matter discovery story wasn't one of a cliché lone genius and a eureka moment. Her observations were a fold in the braid that led to dark matter becoming astronomy dogma. And, her decades of discoveries were only part of her legacy, with her outspokenness and moral compass cementing it to memory. It's this layered legacy I see in the new Vera Rubin Observatory, which will deliver its first images this month. (A century ago, this pioneering astronomer discovered what stars are made of.) Eleven-year-old Vera Rubin—Vera Cooper, then—stared at an imaginary line running down the bed she shared with her sister, Ruth, then rolled over, defeated. She was the younger of the two and was told she couldn't sleep next to the small row of windows that lined the inner wall of the bedroom and fortuitously faced north in their rented townhouse in Washington, D.C. But even from the inside edge, the starlight caught Vera's attention; she was mesmerized. Every night, she'd crawl over her sister Ruth to get a better view of the sky. 'There was just nothing as interesting in my life,' Rubin once said, 'as watching the stars.' Through her childhood in the 1930s, she would hang out by the window tracing star trails, check out library books about scientists, and build her first telescope with her dad, who worked for the Department of Agriculture. He'd also take her to the local amateur astronomy club where she heard talks by astronomers like Harlow Shapley, then the director of the Harvard Observatory. By the time Vera was in high school, she sought out cosmology books like James Jean's The Universe Around Us and Arthur Eddington's The Internal Constitution of Stars. At Vassar College, she majored in astronomy, taught herself how to observe using the college's telescopes, and took summer positions at the Naval Research Laboratory to gain experience doing science experiments. Around then, her parents introduced her to Robert Rubin. They began dating and were married in August of 1948—what many assumed was the end to Rubin's astronomy career. Vera had gotten accepted to Harvard for her master's degree. But she chose to go to Cornell University, where Bob was working on his Ph.D. in physical chemistry, instead. There were roadblocks, but Rubin found mentors in physicist Richard Feynman and astronomer Martha Star Carpenter, and her husband, who helped her launch a research project see if the universe rotated—all while they started a family. When she presented her results at the 1950 American Astronomical Society meeting in Ithaca, New York, the press was sensational. 'A young mother startled the American Astronomical Society,' the Associated Press reporter wrote. Her work challenged convention, and she would again while working on her Ph.D. at Georgetown University. Despite her research, Rubin often felt like an imposter. She earned her Ph.D. in 1954, and about a year later, took a faculty position at Georgetown. She and Bob were growing their family then, and for the next few years, she took on a variety of research projects, always analyzing others' data. Even then an imposter in her own mind, she'd advocate for her students, threatening to pull a paper from publication because the journal wouldn't print the names of the students who worked on it, for example. But, after nearly a decade, Rubin grew tired of relying on others' work to do her own. Finally, she got a break. Observational astronomers Margaret and Geoffrey Burbidge, famous for their paper on the origin of chemical elements in the life and death of stars, invited Rubin to work with them. They were also interested in galaxies and taught her the technique to calculate stars' and gas clouds' speeds. A first taste of being a real astronomer, she said. Shortly after, Rubin knew she needed access to a telescope. She went to the Department of Terrestrial Magnetism, part of the Carnegie Science Institution and talked with radio astronomers there. Then, she asked for a job. She moved into Kent Ford's office on April Fool's Day in 1965 and never left. A few years later, she and Ford discovered Andromeda's flat rotation curve. Then flat curves in other galaxies. By the early seventies, Princeton theorists Jeremiah Ostriker and Jim Peebles were running computer simulations of galaxies to figure how to get the galaxies to stay together in dizzying spirals like Andromeda. Only when the duo enveloped particles representing galaxies in spherical halos in their simulations would the galaxies cease to fly apart. They needed some extra mass to hold them together. Observations and simulations combined, astronomers knew they needed to rethink how the universe worked, and slowly the idea of dark matter took hold. By the early 1980s, consensus emerged: Dark matter existed, most conceded. (How will the universe end? The answer might surprise you.) While this shift was happening, Rubin was pushing for another—equality in astronomy. She worked on an American Astronomical Society report that highlighted issues such as discrimination in hiring, both "blatant or not", a pay gap between men and women with the same qualifications, and lower pay for married women. And, of course, she placed a cutout of a woman on the door of the historic men's-only bathroom at Palomar Observatory in California. Younger astronomers looked up to Rubin, appreciating her candor on sexism and having it all—career, family, and a loving relationship. 'For many of us, Vera had a personal impact. She demonstrated that a woman who was as cheerful, warm, generous, and down-to-earth as she was could be a successful astronomer,' astronomer Deirdre Hunter wrote not long after Rubin's death in 2016. She fostered a sense of belonging, one I felt too. It's how I, at 22, found myself at Kitt Peak with Rubin, on her final time observing, absorbing her life lessons on her grace, wit and grit. She was humble and a deep thinker. Many say she deserved a Nobel Prize. She questioned if she wanted it. 'It changed your life,' she said, and 'not always in a good way.' While studying her galaxy, I sensed of battle of wills, the tug of homelife and professional life. Her husband was ill and her childhood wonder of the universe unfulfilled. Rubin's wonder lives on in the observatory that will bear her name. It will challenge our assumptions just as she did, and I hope it will remind us that her legacy is more than a telescope. It is a blueprint for humanity—to be curious, never assume, and above all be kind. This essay is adapted from the author's book Bright Galaxies, Dark Matter, and Beyond: The Life of Astronomer Vera Rubin.
