squigglyvolcano.bsky.social
Award-Winning Science Journalist | Volcanology PhD | Stories in
@nytimes @sciam @NatGeo etc | Author: SUPER VOLCANOES 🌋 and HOW TO KILL AN ASTEROID 🚀☄️💥☠️
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Hello! I'm writing about the moons for National Geographic and would love to send this to my editor to see if we can include it. Can you email the files to me on [email protected] with appropriate credit, if you'd be okay with that? Thanks in advance!
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oooh, very nice
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🫡
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Emailed. Old school.
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Yep! Very cool. Emailed. :)
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I shall reach out for a chat. Writing a story on this (of course)
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Oh sweet!!
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Wait, the legendary @sundogplanets.mastodon.social.ap.brid.gy is a co-discoverer??
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!? amazing!!!
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Asteroid 2024 YR4 isn't likely to be a problem at all; it'll probably miss Earth. But if it doesn't, we have to be wary of trying to save the world but accidentally making the problem worse.
Maybe we'll just have to get out of the asteroid's way this time.
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Maybe 2024 YR4's odd will rise, and we will successfully deflect it in 2028 using a monster-sized spacecraft. Or maybe we'll break an awkward taboo and instead opt to use a nuclear warhead to try to deflect it, which would provide a bigger punch to the asteroid than DART.
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I'm not saying a kinetic impactor mission, or missions, couldn't work. But we don't have much time, and we don't have enough info about this rapidly fading asteroid to properly inform our planetary defense decisions yet.
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And with only a few years down the line, we could accidentally deflect it—but not enough to make it avoid the planet. Then, it still hits Earth, just somewhere else that wasn't going to be hit.
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It may be smaller, or larger. If it's too big, we may not be able to deflect it with one spacecraft. We'd need several to hit it perfectly, all without catastrophically breaking it.
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Yes, it's smaller than Dimorphos (YR4 is 40-90m), meaning it would need less of a deflection than a larger asteroid. But we aren't going to see it again until another Earth flyby in 2028. So much could go wrong if we try and hit it with something like DART.
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Now let's look at 2024 YR4. We have less than eight years to potentially deal with it, if needed.
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I've often by told you need 10 years or more to build, plan and execute an asteroid deflection mission. This is because the deflection a kinetic impactor can give an Earthbound asteroid would be tiny. Only over time does the shifted orbit add up enough to ensure it'll miss Earth.
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The second reason DART isn't a silver bullet is that it did not give Dimorphos as much of a deflection as you think. Yes, the orbit shrank a lot. But you know how much Dimorphos actually moved?
The change in velocity delivered by the impact was 2.7mm/s. www.llnl.gov/article/4954...
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This is chaotic, potentially very destructive—and if DART hit Dimorphos a little harder, it would have broken that asteroid too. You have to be very sure that when you hit an Earthbound asteroid, you are deflecting it, not fragmenting it.
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Nobody wants to accidentally "disrupt" an asteroid, because those components can still head for Earth. As I often say, it's like turning a cannonball into a shotgun spray.
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The first is that asteroids like Dimorphos, and smaller, tend to be rubble piles: not solid single rocks, but boulders weakly bound by their own gravity. Hitting them just right can produce that debris-like thrust effect, but if you hit them too hard, you'll shatter them.
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So, DART worked. But it doesn't mean we can use kinetic impactors like it to deflect any asteroid whenever we want, and that's for several reasons.
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One of my favourite parts of the DART mission is that it knocked off so much debris from this asteroid that it created a 30,000km-long comet-like tail that persisted for many months after impact day.
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It worked wonders: it shrank Dimorphos' orbit by 33 minutes, making the deflection 25x more effective than the baseline. It did this because, as DART smashed into the asteroid, lots of debris flew back off the asteroid, acting like a rocket jet and giving it more of a push.
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If it worked, it proved that a type of asteroid deflection technique -- using a kinetic impactor spacecraft to deflect an asteroid away from Earth -- works on a fundamental level. Nobody had ever tried anything like this before, so no-one could be sure if it would work.
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It's aim was to crash a van-size largely autonomous spacecraft into the asteroid Dimorphos, which orbited a larger asteroid named Didymos. Their aim was to "deflect" Dimorphos—in this case, by shrinking its roughly 12-hour-long orbit around Didymos by 73 seconds.
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The DART mission was Earth's first planetary defense experiment, and it was an incredible success. It's the main narrative arc of my book for a good reason: it showed, for the very first time, that we can rearrange the cosmos to make it more habitable.
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ew
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A fun, albeit very remote, possibility.
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Thanks to @asteroiddave.bsky.social @michael-w-busch.bsky.social Gareth Collins (and to @asrivkin.bsky.social, who sadly couldn’t squeeze into this short story post-edit).