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... - ThreadSky

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squigglyvolcano.bsky.social • 28 days ago

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. https://www.llnl.gov/article/49541/study-looks-velocity-impact-asteroid-dimorphos

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squigglyvolcano.bsky.social•28 days ago

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.

squigglyvolcano.bsky.social•28 days ago

Now let's look at 2024 YR4. We have less than eight years to potentially deal with it, if needed.

squigglyvolcano.bsky.social•28 days ago

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.

squigglyvolcano.bsky.social•28 days ago

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.

squigglyvolcano.bsky.social•28 days ago

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.

squigglyvolcano.bsky.social•28 days ago

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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