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À partir d’avant-hierArs Technica

The secret to protecting next-gen spacecraft might be eggshells

In 2007, a piece of space debris punched a bullet-like hole through the radiator panel of the US space shuttle Endeavor. The shuttle program ended in 2011, but the space debris problem has only intensified as we launch more and more satellite constellations, telescopes, and spacecraft into orbit. That's why Chinese scientists have devised a new aluminum material inspired by eggshells that they believe could offer enhanced protection against debris fragments, according to a new paper published in the Journal of Applied Physics.

Eggshells have long fascinated scientists because of their mechanical properties. For instance, it's well known that cracking an egg requires applying just enough force to the center to achieve a clean break without completely shattering the shell. In 2012, MIT mechanical engineer Pedro Reis co-authored a paper demonstrating the link between an egg's ovoid geometry and its rigidity, a major factor when predicting how much force an object can endure before cracking. (As I wrote for Slate at the time, rigidity is related to, but distinct from, strength. If one eggshell has tiny cracks and the other doesn't, both shells have different strengths—the cracked one will break more easily—but the same rigidity.)

Reis started studying eggshells after participating in a popular physics demonstration: walking on cartons of eggs without breaking them. The key, he learned, was to align the eggs with their narrow tip (the most crack-resistant part) pointing up, and then carefully place one's feet to distribute one's weight over the entire surface area. This ensures that no single egg is overloaded. While it takes around 5.5 pounds of force to crack an egg, that depends on the direction in which the force is applied, as well as its distribution over the shell's surface.

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Ars Asks: Share your shell and show us your tricked-out terminals!

I spend more time today than ever before interacting with terminal windows, which is something I don't think Past Me would have believed in the early '90s. Back then, poor MS-DOS was the staid whipping boy of the industry, and at least on the consumer side, graphical environments like Windows (and maybe even odder creatures like AmigaOS) seemed poised to stamp the command line into oblivion, leaving text interfaces behind as we all blasted into the ooey-GUI future.

As it turns out, though, the command line is still the best tool for some jobs—many jobs, in fact. I read a wise post some years ago (probably on Slashdot) arguing that a mouse-driven point-and-click interface essentially reduces the user to pointing at something on the screen and grunting, "DO! DO THAT!" at the computer. (The rise of right-click context menus adds the ability for the user to also grunt "MORE THINGS!" but doesn't otherwise add vocabulary.)

The command line, by contrast, gives the user the opportunity to precisely tell the computer what they want done, using words instead of one or two gestalts that the computer must interpret based on context.

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