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Scientific American
08-05-2025
- Science
- Scientific American
This Soviet Spacecraft Will Soon Crash-Land on Earth
A defunct spacecraft from the former Soviet Union that has been stuck in space for more than half a century is, at last, about to come home. Kosmos-482 was launched on a voyage to Venus in March 1972 as part of the Soviet multimission Venera program. Thanks to a rocket malfunction, however, it never escaped Earth orbit. Most of its launch debris fell back to our planet's surface within a decade—but a half-ton, three-foot-wide, spherical 'descent craft' remained in a high elliptical orbit that looped from 124 miles to 6,000 miles in altitude. Ever since, it's been spiraling out of control back down to Earth, slowly losing altitude during its lower passes as it bleeds off momentum against the tenuous wisps of our planet's upper atmosphere. Sometime in the next few days (no one can say exactly when), over some part of our planet (no one can say exactly where), that doom spiral will end as Kosmos-482 dips down into lower, thicker air and begins a final, fiery plunge through the atmosphere. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Such uncontrolled reentry events are relatively common and rarely merit much notice. Typically, in such cases, the spacecraft merely streaks across the sky as an artificial meteor as it breaks apart and burns to ash at high altitude. What makes Kosmos-482 different is that its descent craft was encased in a titanium heat shield so that it could endure a brutal atmospheric entry at Venus—and thus it has a very good chance of reaching Earth's surface more or less intact. 'Because it has a heat shield, it's likely to come down in one piece until it hits the ground,' says Jonathan McDowell, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian, who closely monitors spaceflight activity and helped identify the stranded spacecraft's strange situation some 25 years ago. 'So you've got this half-ton thing falling out of the sky at a couple hundred miles an hour, which sounds scary. I mean, it's a bit like a small plane crash, right? That's not great.' Should We Worry about Kosmos-482? The chances of anyone being killed or injured by Kosmos-482 are decidedly low. 'I'm not too worried,' says Marco Langbroek, a scientist at Delft Technical University in the Netherlands, who has spent years tracking the spacecraft's decaying orbit. 'There is a risk, but it is small—in the same ballpark as that of a meteorite fall.' Other troubling, recent reentry events have carried greater risks, Langbroek notes, such as falling debris from rockets launched by China and by the U.S.-based private company SpaceX. In February an upper stage from a SpaceX Falcon 9 rocket showered Poland with several chunks of debris. And in recent years large, deliberately jettisoned components of the company's Crew Dragon spacecraft have fallen on Australia, the U.S. and Canada. In several launches, worrisomely hefty debris also reached Earth from uncontrolled reentries of the core stage of China's Long March-5b heavy-lift rocket. And even the International Space Station shed debris that ended up falling on a house in Florida. While various claims of property damage and emotional distress have been made, so far none of these events has physically harmed anyone. When and Where Will Kosmos-482 Fall? In short, no one really knows. As of this writing, Langbroek forecasts that Kosmos-482's reentry will occur on May 10, shortly after 3:30 A.M. EDT. But this estimate, he notes, comes with a 14-hour fudge factor on either side. The closer the spacecraft gets to its point of no return (its first contact with sufficiently thick air to hit the brakes on its orbital velocity), the more certain the forecasts will become. Another recent estimate, from the private Aerospace Corporation, predicts a reentry a few hours earlier, albeit with an 18-hour uncertainty. One complicating factor in these predictions is the fluctuating puffiness of Earth's atmosphere, which can swell or shrink based on how much it's being battered by solar wind and other space weather events. Given its current orbit, the spacecraft's potential landing area encompasses most of Earth's surface between 52 degrees north and 52 degrees south latitude. This means it could make landfall anywhere in Africa or Australia, in most of North or South America, or in broad swaths of Asia or Europe. Or, most likely, it may instead splash down somewhere in the vastness of the global ocean that lies between those latitudes. All these uncertainties serve to compound the problem of forecasting Kosmos-482's exact impact point. Because the spacecraft will be moving at some 17,000 miles per hour whenever it begins to plow through thicker air and slow down, even a slight discrepancy in its predicted versus actual position at that point would result in a large change in its final destination on the spinning Earth below. What Happens Next? Whether intact or fragmented, in the likely event that the Kosmos-482 descent craft reaches our planet's surface, it will be considered the property of Russia. 'Legally, as the successor to the Soviet Union, the Russian Federation is responsible for the object—and any damage it might do,' Langbroek says. And because of its titanium shell, he expects that the spacecraft may only suffer slightly from its impact. 'Basically, what we have here is a time capsule with 53-year-old Soviet technology returning to Earth,' he says. 'If it could be recovered, this would be true 'space archaeology!' To quote Indiana Jones, 'It belongs in a museum!'' Assuming any material is recovered, however, international law dictates that the decision to study or display any of it would be Russia's to make. For Asif Siddiqi, a space historian at Fordham University, who is one of the world's foremost scholars of the Soviet space program, the return of Kosmos-482 is a literal 'object lesson' about the wealth of archaeological artifacts preserved in space. 'Low-Earth orbit is a kind of archive of the cold war space race,' he says. 'It's amazing how much stuff is out there waiting to either occasionally intrude upon our thoughts—or, if we're super ambitious, for us to retrieve to actually put in a museum.... There are all sorts of things—spy satellites, failed probes, used-up stages, secret weapons, who knows—silently orbiting the Earth, their batteries used up, film exposed, radios burnt out. And not all of it is benign: there are a whole bunch of abandoned nuclear reactors from the Soviet radar ocean reconnaissance satellites still orbiting the Earth. The people who designed and built all this stuff are mostly dead and gone. But their handiwork is out there.' Although each individual uncontrolled reentry event poses low risks, McDowell says, we must be cognizant of 'the continued rolling of the dice' that these events collectively represent. 'This is part of the environmental legacy of the cold war,' he says. 'There's all this rubbish left in space that's now, decades later, coming down. And this is simply what these long reentry timescales give us, right? Here we are, a quarter of the way through the 21st century, and suddenly these things from the 1970s are knocking on our door for attention again.'
Yahoo
25-04-2025
- Science
- Yahoo
Scientists discover super-Earth exoplanets are more common in the universe than we thought
When you buy through links on our articles, Future and its syndication partners may earn a commission. Astronomers have discovered that "super-Earth" planets may exist on wider orbits than previously thought — and this implies these rocky, or "terrestrial," worlds are far more common than was suspected. Super-Earths, in short, are planets with masses up to 10 times that of our planet, but still less than the masses of gas giant planets. The discovery came after a small extrasolar planet, or "exoplanet," in a wide orbit around its star was discovered, courtesy of a gravitational "microlensing" event designated OGLE-2016-BLG-0007. This event indicated the exoplanet had a planet-to-star mass ratio that roughly doubles the Earth-sun mass ratio. "We found a small planet in an orbit similar to Saturn's. This planet is part of a larger sample that shows super-Earth planets between the orbits of Earth and Saturn are abundant," team member Jennifer Yee of the Center for Astrophysics | Harvard & Smithsonian told "The abundance of super-Earths was a surprise." Yee explained that scientists previously knew from data delivered by the Kepler space telescope mission that super-Earths are common around other stars, but only within a distance from their respective stars equivalent to the distance between Earth and the sun. That expected distance is represented by one astronomical unit (au). This new work, however, shows that super-Earths are also common at larger distances from their host stars, in this case around 10 au (or 10 times the distance between our planet and the sun). "Previously, there were only upper limits on the numbers of super-Earths [in wide orbits], and there was a suggestion that they might not exist at all," Yee continued. When factoring in this super-Earth data, the team calculated that there should be around 0.35 super-Earth planets per star on wide Jupiter-like orbits. Yee explained that the overall distribution of planetary mass ratios could reflect the specifics of planet formation processes. "Specifically, the distribution suggests that the planets can be separated into two populations, one of super-Earths and Neptunes and one of more massive gas giant planets," Yee added. The team suspects this division in populations reflects the differences in formation processes between terrestrial planets and massive gas giant a larger population of super-Earths in Jupiter-like and Saturn-like orbits could also have implications for our understanding of so-called "habitable zones" around other stars. Habitable zones are defined as regions around stars that are temperate enough to allow liquid water to exist at the surfaces of terrestrial planets within the area. Any closer to a star than its habitable zone band, and a planet's liquid water evaporates. Further away, it freezes. This is why habitable zones are also called "Goldilocks zones" (like the perfect bear's porridge, liquid water is neither too hot nor too cold in these zones). Though Jupiter and Saturn are outside the solar system's habitable zone, super-Earths in similar orbits around hotter stars could fit within such regions — if they are extended. "The habitable zone region where we expect to find life in other planetary systems is extremely narrow. Our expectations regarding this zone have been driven by our own planet because that is the only place where we have definitively detected life, so far," Yee said. "Nature continuously surprises us."Yee added that the best way to understand the habitable zone region around stars in general is to measure the properties of the larger planet population. "This gives more room for the unexpected," Yee said. "This measurement of the super-Earth population provides a new piece of the habitable zone picture, which will ultimately contribute to our characterization of the population of Earth-like planets." Yee and colleagues made this discovery using the Korea Microlensing Telescope Network (KMTNet), consisting of three sites in Chile, South Africa and Australia. The three telescopes in three different time zones mean KMTNet can allow astronomers to monitor the night sky uninterrupted over the southern hemisphere. "This discovery of this planet wasn't a surprise because KMTNet was designed to do this, but it is extremely exciting because it proves KMTNet is capable of routinely finding smaller planets, which is a requirement for understanding planet populations," Yee hunts exoplanets using a phenomenon first predicted by Albert Einstein in his 1915 theory of gravity, general relativity. General relativity suggests objects with mass cause the fabric of space and time to "warp," with gravity arising from this curvature. When light passes by this curvature, its light gets curved, too. That means when a body of mass comes between Earth and a background light source, the image of that source is warped, magnified, or even multiplied upon reaching our instruments. A planetary system acting as a gravitational lens and coming between Earth and a background source can cause a tiny distortion in that source, a situation called "microlensing." "It is a funny coincidence of physics," Yee said. "Microlensing is good at finding planets near the Einstein radius [the characteristic angle for gravitational lensing]."This radius is set by the mass of the lensing planetary system, including its star, the distance from Earth to that lens system, and the distance from Earth to the background source whose light is distorted. "In fact, it was the realization of this coincidence in the early 1990s that led to the first microlensing planet searches," Yee added. Related Stories: — Scientists discover bizarre double-star system with exoplanet on a sideways orbit (video) — Does exoplanet K2-18b host alien life or not? Here's why the debate continues — Earth-size planet discovered around cool red dwarf star shares its name with a biscuit The team will now continue to use KMTNet and gravitational lensing to hunt for lensing planetary systems in an attempt to discover more super-Earths in wide orbits. "We are working on increasing the size of the planet sample by including more seasons of KMTNet data in the analysis," Yee concluded. "We are also working on improving the quality of the data reductions to allow us to find weaker planetary signals."The team's research was published on Thursday (April 24) in the journal Science.
