Woo! Science is a column of science news and newsmakers in Worcester and the region. Got a science news idea? Email Margaret Smith at [email protected]. Do you ever look up at the night sky, at the twinkling lights in the darkness, and wonder ... is one of those things going to come crashing down on my house? If you were wondering that recently, you weren't alone, when the discovery of an asteroid, prosaically dubbed Asteroid 2024 YR4, reported Dec. 27, 2024, by an observer in Africa to the Minor Planet Center of the International Astronomical Union. Its size, about 130 to 300 feet long, could evoke a scene out of a Will Smith movie if it fell on top of, say, a major city. As astronomers gathered more data, however, that risk, began, well, to fall. "I think a lot of people have been hearing about the asteroid, 2024 YR4. The news was very much about the potential asteroid impact in 2032, and when it was up to 3%, it's higher than most things," said Melanie Meadors, science communicator and public outreach coordinator for the Aldrich Astronomical Society. "But what they weren't reporting is that what usually happens when we discover an asteroid that could cross paths with the Earth, is that once scientists start to study it, statistically what they're seeing is that it might have impact, and the impact goes up just because they are collecting more data about it." Meadors said, "Once they learn more about the object's orbit around the sun, the likelihood drops dramatically."
The cosmic junkyard
But there's plenty up there to think about, said Meadors, including an eerie allotment of decades-old dead, manmade objects within our planet's gravitational pull. "What a lot of people are concerned about over all, in general, is that there is a lot of stuff in orbit around the Earth, manmade garbage," Meadors said. Meadors added, "A lot of times, it will hit, usually in the ocean. That is something we should be more cognizant of, and put more thought into what we are putting up there. Once it dies, it is floating around forever. The International Space Station will be at risk, and other satellites we really need." A case in point: a European Space Agency satellite, known as ERS-2, launched in 1995 and inactive since 2011, tumbled through the Earth's atmosphere, and landing in the Pacific Ocean somewhere between Alaska and Hawaii. An array of contraptions, dating back to the Space Race of the 1950s and early 1960s, still make their way around, silent relics of that contest between the U.S. and the Soviet Union. "There is all kinds of stuff from when our space program started. Some stuff just stays up there," said Meadors. "We are going to get to a point where we delay launches, because there is going to be so much stuff we need to avoid." NASA has programs to track larger pieces of debris, but as more nations begin to deploy more satellites and other objects, the field, as it were, will get more crowded, and collisions can and do occur.
In 2021, a Chinese military satellite sustained a hit from debris, possibly from a Russian object. Shedding light on it, or not
A congested space around the Earth with both active and inactive satellite and other hardware can also make it more difficult to track objects, both natural and manmade. Meadors said this can contribute to the problem of light pollution, when illumination both from and above the Earth makes it harder to see objects in space, and may create problems for species on Earth depending on darkness for their survival. "Light pollution is becoming a really big problem," said Meadors."The more light there is in the sky, caused by city glow, the less light we can collect from stars and planets, and so forth. It affects us being able to detect things. We had a momentary risk where we wondered if it hit the Earth. It affects our ability of detecting things like that — not just to discover new things for exploration purposes, but also, to keep ourselves safe." Remember the Space Force? One of its jobs is following satellite traffic. "There are U.S government entities in the Space Force that track all the satellites that are up there, above a certain size," said Kelly Beatty, of Chelmsford, senior editor of Sky & Telescope. "There are almost 48,000 objects as of now, objects in orbit that can be tracked. There are at least a dozen countries that can launch satellites, and of those, about 11,300 are active satellites." And of those 11,300, some 7,000 belong to Starlink, the subsidiary of SpaceX, whose owner's name should ring a bell: Elon Musk." At last count, Beatty said, there were plans to increase this number to 12,000. SpaceXalready has otherworldly woes. On March 6, the upper part of the Starship spacecraft
exploded for a second time, some minutes into its flight test , sending flaming debris
visible from Florida to the Caribbean . The fiery mishap
marked the second consecutive failure for the 400-foot spacecraft this year, which is being developed for future crewed missions to both the
moon and
Mars .
Gravity is a drag
What makes an object circling the Earth likely to come hurtling back down? There are a lot of factors, including the object's size, how high it is, how dense it is, the pull of the Earth's gravity, and the pull of the Earth's atmosphere. Objects in the range of 200 to 500 miles in altitude are likely to get the drag of the atmosphere, Beatty said. NASA's Center for Near Earth Object Study tracks asteroids, comets and other objects. "Satellites have an orbit that is defined mathematically," said Beatty. "If you run the numbers backward and foreword, you know where it would be in the future. And the same is true for asteroids. If you know those numbers for asteroids, you run it to determine if it has any chance of hitting the Earth. A smaller object might simply burn up on entering the Earth's atmosphere. But what about larger objects? Can we predict where they will fall? "We are talking about things that can be the size of a car or a truck, that can come in an uncontrolled way. When that happens, there is nothing we can do about it," said Beatty. "All is we can do is, as it's getting lower and lower, to watch the likely places where it's going to come down." The thing is, once it hits the atmosphere, it's likely to get jogged around a bit, making its trajectory tricky. "These satellites are not homogenous all the way through," Beatty said. "It might be a big shell of aluminum, and the middle of it is something like a fuel tank, or something very dense, that might make it to the ground."
On the lookout
The Interagency Consultative Group, a loose federation of space-faring nations have agreed that before launching anything into space, it must have a controlled way to be returned to the Earth, Beatty said. "You would hope that they would follow it." Another thing to consider: inclination of the orbit, the tilt of an object's orbit around a celestial body such as the Earth. The federation would require this formula to be taken into account, to increase probability that were an object to come crashing down, it would hit an ocean: a likelihood in our favor, said Beatty, given the Earth is three-quarters covered by ocean. If by chance, you're looking up from Worcester, you might see the International Space Station fly overhead. Beatty said the latitude of Worcester, 42.3 degrees, would make it quite vulnerable if the space station to fall, a very highly unlikely scenario. "Its average altitude is about 250 miles," said Beatty. "It has big solar panels on it. Eventually, it will come crashing down, so one of the thigns that has to be planned for is, how do you get the pieces to Earth?" Beatty noted that on Feb. 10, 2009, two satellites collided in orbit, an Iridium Communications satellite, and a dead, derelict Russian military satellite, known as Kosmost 2051. "They collided at 26,000 miles per hour, over Sibera, and obviously, it destroyed them both," Beatty said. "So, yes, this stuff can happen." A large radar dish at Haystack Observatory in Westford is also used to track satellites, and a telescope in Chile is activated to track objects in the sky over the southern hemisphere. Beatty said NASA has some 38,022 near-Earth asteroids in its database, of which 2,472 have potential to strike the Earth. Of those, 152 are potentially hazardous, with 152 being at least one kilometer across, or about a half mile. "If a one-kilometer object hits the State House in Boston, basically, all of New England woudl be gone," Beatty said. One asteroid has a 10% chance of hitting Earth sometime between 2095 and 2122. It's only about 30 feet across, and might well crumble upon impact with the atmosphere, but it might give our great grandchildren something to tell their kids.
We've got you covered, sort of
If you're feeling misty about that solar eclipse that semi-darkened the land on April 8, 2024, greeted by fans with watch parties and a sense of wonder, we've got another one on the way. It may not rate as dramatically as year's, which saw 90% coverage of the sun when the moon passed between the sun and the Earth. But, for true lovers of all things celestial, it might just be worth getting up around on dawn on March 29, when Beatty said, "about half of it will be covered." The proportion of coverage of the sun increases along points north, including up the coast of Maine. "So, at Bar Harbor, it's more like 80%," Beatty said. According to NASA's timetable, the greater Boston area will begin to witness the eclipse starting at 6:31 a.m., reaching 43% coverage by 6:38 a.m., with the whole thing over at 7:07 a.m. If you still have those eclipse glasses from April 8, why not take them out, and get ready for the show? And if it seems like a coincidence that a lunar eclipse of the so-called blood moon occurred March 14, Beatty said it's not unusual for lunar and solar eclipses to occur within a short time of one another.
