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  • [♪ INTRO]

  • We've had the technology to reuse rockets for decades now;

  • they were a staple of the Shuttle days.

  • But the Shuttle's solid rocket boosters weren't too impressive in their return home.

  • They just splashed down into the ocean.

  • Now we're in the era of rockets that can land themselves on floating platforms.

  • But that's a tricky feat,

  • and those tiny legs at the bottom have to withstand a lot of force in the process.

  • So one team of engineers is trying to develop a new material

  • that could lessen that force, and in turn, soften that dangerous landing.

  • Last week in the journal Science Advances,

  • they showed how they were inspired by the ancient art of paper folding: origami.

  • Researchers based at the University of Washington decided to try

  • counteracting the compression waves, basically a pushing force,

  • that would travel through a material during a collision.

  • Like when the legs of a rocket hit the landing pad.

  • For that, they designed a type of mechanical metamaterial.

  • Metamaterials are a type of artificial material built from repeating units,

  • think Lego bricks, that engineers can manipulate to create new properties.

  • It's figuring out what those bricks need to look like that's the tricky part.

  • That's where the origami comes in.

  • This team used a laser cutter to form a specific pattern of creases in a piece of paper,

  • then folded that into a cylinder-esque shape.

  • On either end they glued an acrylic hexagonal cap.

  • So when the cap was pushed on, the cylinder buckled in a pattern determined by the creases.

  • But it could also spring back into its original shape.

  • They linked 20 of these cylinders together in a column.

  • Then they subjected their column to compressive forces.

  • And their column was able to transform that push into a pull.

  • See, even as the column was compressed,

  • each little cylinder also resisted that push and straightened out slightly.

  • This created a pull within the structure, or what's technically known as a rarefaction.

  • And as both the push and pull propagated along the column,

  • the pull actually traveled faster, so the whole structure resisted being squished.

  • What's also cool about this research, besides the whole origami rocket part,

  • is that previous strain-lessening methods required hundreds of metamaterial units.

  • This new origami structure needed only ten.

  • There are some limits to the research, though.

  • The team only looked at the system in one dimension.

  • Also, they had to do the paper folding themselves,

  • so, any real-world application of this tech is going to need to develop beyond that.

  • But this new method doesn't need to be limited to rockets,

  • it could be applied to all sorts of situations where collisions are involved,

  • like designing helmets.

  • It's a new way to protect against all sorts of dangers.

  • And another, more astronomical danger was in the news this week.

  • Coronal mass ejections, or CMEs,

  • are a stream of high-energy particles thrown off the Sun with little warning.

  • They're the most powerful magnetic anomaly our star creates,

  • and when the particles reach us they can interfere with electrical equipment,

  • including satellites and, if the CME is powerful enough,

  • things like radio transmission down here on Earth.

  • They can often accompany solar flares.

  • But our Sun isn't the only star that creates these blasts.

  • And this week in the journal Nature Astronomy, astronomers have turned their attention

  • to coronal mass ejections coming from something other than our sun.

  • A team based out of Palermo, Italy used the Chandra observatory to study

  • the x-ray light emitted from the star dubbed HR 9024,

  • which is located about 450 light years away.

  • It's also a bit bigger than our Sun, as well as a bit hotter, so bluer.

  • But most importantly, it's consideredactive”,

  • meaning it emits way more energy per second on average.

  • And they spotted a flare, analogous to a solar flare, coming from this star.

  • By analyzing the star's spectrum, or its light signature,

  • they were able to identify specific elements present in the flare.

  • Different elements show peaks in the spectrum at different wavelengths.

  • In order to separate what's coming from the star's atmosphere and the actual CMEs,

  • they used the Doppler effect.

  • This is the same effect that makes an ambulance siren coming toward you sound higher pitched,

  • and one moving away from you sound lower.

  • Light or sound waves moving toward us are compressed relative to us,

  • and those moving away get stretched out.

  • For sound, that changes the pitch; for light, the color.

  • So a light source moving toward us gets bluer, and moving away, gets redder.

  • By tracking specific peaks in HR 9024's spectra, comparing where they should be

  • if they're not being ejected to where they appear, the astronomers could tell

  • which elements were moving toward or away from us.

  • And that's the material that's in the flare.

  • They found sulfur, silicon, and magnesium inside a giant plasma loop,

  • associated with the solar flare.

  • On top of that, there was an additional line of oxygen that was cooler and out of step with the flare.

  • That, the researchers think, indicates the presence of a CME.

  • Based on that assumption, they estimated that CME's mass: about one billion billion kilograms.

  • But they weren't able to determine if any of that mass successfully

  • escaped the star's gravitational pull and would go forth to irradiate hypothetical planets.

  • In comparison with CMEs from our Sun, it released more energy,

  • but not nearly as much as they had predicted.

  • This is just one initial step in actually investigating how stars different from our Sun behave.

  • Math only gets us so far, and this result might mean

  • stellar CMEs are more different than we thought they'd be.

  • Which could mean a lot of things, and even, theoretically,

  • influence the development of life on those stars' planets.

  • Thanks for watching this episode of SciShow Space News,

  • and thanks to our great Patreon supporters who help us make episodes like this.

  • If you want to join them, check out patreon.com/scishow.

  • [♪ OUTRO]

[♪ INTRO]

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摺紙如何改變火箭設計 (How Origami Could Change Rocket Designs)

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    林宜悉 發佈於 2021 年 01 月 14 日
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