May 21, 2024: The incredible feather, space junk is piling up, and how cockroaches took over the world. —Andrea Gawrylewski, Chief Newsletter Editor | | | For as many varieties of birds there are in the world, there is an equal array of feathers that help the animals fly, keep warm and even swim quickly. For birds that fly, feather shape evolved to enhance aerodynamics. Namely, a feather is aerodynamically asymmetrical, so that the trailing edge of the feather is three times wider than the leading one. | | | Powered flight—that is, flapping flight rather than gliding flight—probably evolved multiple times in dinosaurs, with just one of those lineages surviving to the present in the form of birds. Feathers' ability to twist in just the right way enabled slotting, which makes the wing much more efficient at low flight speeds. | | | Each feather type is incredibly adapted to environment and purpose. The slotted feathers of the Greater Prairie Chicken, a type of grouse, allow it to spring quickly into flight if startled; hummingbirds have ultrastiff feathers that allow them to hover in midair and dart around; the flightless penguin has a dense netting of small feathers that reduces drag in water and makes it easier to swim. | The wing of the Greater Prairie-Chicken, a type of grouse, has a slotted tip that helps the bird burst into flight when startled. Robert Clark | Facial disks of feathers around the eyes and ears of owls funnel sounds to their inner ears, helping them zero in on prey without seeing it at all. | What the experts say: Feathers have inspired a range of products and technological innovations. "The silencing fringes of owl feathers have inspired ventilation-quieting systems. The surface texture and boundary-layer-control principles of penguin feathers have made their way into robotics, mostly in prototypes," writes Michael B. Habib, a paleontologist and biomechanist at the Natural History Museum of Los Angeles and the University of California, Los Angeles. | | | The U.S. Air Force tracks more than 25,000 pieces of space junk larger than 10 centimeters—about the size of a bagel— weighing together some 9,000 metric tons. This dangerous trash zips around Earth at speeds of roughly 10 kilometers per second, or more than 22,000 miles per hour. Smaller junk routinely hits satellites, and pieces of debris plummet to Earth, striking homes or killing people. It's past time for an international treaty that limits space junk, outlines responsibilities and imposes fines on the companies whose spacecraft mess causes harm, write the editors of Scientific American.
Why now: Almost 10,000 satellites are orbiting Earth right now, up from 6,500 only three years ago. The nearly 6,000 Starlink satellites launched by Elon Musk's SpaceX now make up more than half of the total, and they are part of a planned fleet of up to 42,000. Collisions of satellites would instantly double the amount of trackable debris in orbit and create countless smaller, yet still dangerous, bits of space junk. Such damage could represent a trillion-dollar cost to humanity every year, by the next century.
What the editors say: "We live in a new era of private space exploration, one that is more extractive and invasive than before, with many nations and companies participating. We need better rules to keep us from trashing Earth's orbit as badly as we have trashed Earth itself." |  | Amanda Monta├▒ez; Source: "Satellite Statistics: Satellite and Debris Population," Jonathan's Space Report (data) | | | • Chemists are developing "clean ammonia" to replace shipping fuel. | 6 min read | | | • A survey of hundreds of residents in towns hit by hurricanes showed that about half had lost income as a result of the storms. | 2 min read | | | • Judges and law enforcement commonly use an algorithm, called CPORT, to estimate the risk that a child pornography offender will offend again. Its use influences which convicted sexual offenders should be placed on the public sexual offender registry. But that algorithm is based on limited and outdated data and has shown mediocre predictive abilities at identifying repeat offenders, write professors of psychology Nicholas Scurich and Daniel Krauss. "Inaccurate predictive algorithms offer the appearance of scientifically based precision and accuracy. But that appearance is illusory, and, in actuality, legal decisions based upon them lead to significant errors with dire consequences," they say. | 5 min read | | | A principle in economics called the "tragedy of the commons" suggests self-interested parties of an ungoverned, limited resource end up overusing and destroying that resource. This concept is common in environmental science, where humans overuse and exploit resources like grazing land, fisheries or the vacuum of space. Starting in the 1960s, Elinor Ostrom--the first woman to win the Nobel prize in economics--found that common property isn't always ruined, especially if users establish rules to mitigate damage. Let's see if billionaire spacecraft owners and governments can play nice and address the tragic commons of low Earth orbit. | This newsletter is for you! Reach out anytime and let me know how you think we're doing: newsletters@sciam.com. I read all your notes and respond to many. See you tomorrow! | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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