Planetary defense test deflected an asteroid but unleashed a boulder swarm

L4sBot@lemmy.worldmod to Technology@lemmy.world – 85 points –
Planetary defense test deflected an asteroid but unleashed a boulder swarm
newsroom.ucla.edu

Planetary defense test deflected an asteroid but unleashed a boulder swarm::A UCLA-led study of NASA’s DART mission determined that the strategy presents previously unanticipated risks.

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So the thing that was meant to be a learning experience turned out to be a learning experience?

Somehow, I found the lead scientist's statement and the associated news to be click-baiting. Right, you crash something into a composite rock, and expect no ejecta from it. That's pretty freaking believable. That's like, the most basic physics you can expect from it. This is just to grab your attention so we can get more funding (which they may deserve, even if this is irritating), folks.

Wasn't it boulders like laying around on the asteroid? Held there by microgravity, and thus knocked in all directions at the impact?

I mean debris from the impact, yes, "boulders" laying around, no I didn't expect that :-)

OK. Then. I guess the summary would be like, the asteroid was more loose than we though, and we had no idea how the boulders got ejected from the surface because our impact.

Totally totally totally unanticipated that one. Like every discussion about asteroid defence ever anticipated exactly this kind of scenario.

Unanticipated? I'm sure I can pull out a very serious and scientific simulation that predicted this exact event from 1979. It's called Asteroids I think.

Pretty cool they were able to measure the change in velocity of an object 6 million miles away with millmeter/second resolution. Not cool that it only slowed down a few mm/second though

Actually, a few mm/sec is quite a lot. That could easily be more than enough to deflect an asteroid from hitting earth. That few mm/sec will accumulate over the time it takes the asteroid to travel six million miles.

Well you would need the vector to predict that not just the speed (which they likely have, didn't see it in the article), but pretty cool nonetheless

Sounds like the gravity tug or thruster methods might end up being the better solution.

Why is this a problem?

The point is to deflect asteroids decades or even centuries out. If they do that then the boulders they eject will still be in the same gravitational area and will still move with the parent object. I doubt the force of impact is going to send them on completely new courses. And even if they did it's unlikely that the new course would be the same as the old course, if anything it would be either the reverse of the old course, or a tangent to it.

Asteroids may be detected very late when they're already near earth. Breaking up a large rock into a lot of smaller ones may not be a big help. But all of this has been known for a very long time.