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Kraagenskul t1_iqwf196 wrote

Seems interesting, but can somebody smarter than me ELI5 this?

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Override9636 t1_iqwnegf wrote

If there is a asteroid on a collision course with Earth, and it's big enough to cause some catastrophic damage, everyone on the planet will want some plan in action to make it go away. The simplest way to do that is to be able to do that is to alter the path of the asteroid ever so slightly that its course misses the Earth. Even though a satellite has very little mass, if you make it travel fast enough, you can impact enough velocity to give a big asteroid a nudge. Even if it's a tiny bit, that redirection propagating over millions of km will save the planet.

DART's mission target was actually a smaller space rock (roughly the size of the pyramid of Giza) that was orbiting a larger asteroid. Since they could easily detect the smaller rock's orbital period, they could calculate how much the impact would change its orbit. This would better inform scientists about what to expect from future redirect missions so that we could make a robust planetary defense system in case The Big One ever shows up.

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xGHOSTRAGEx t1_iqwtr55 wrote

How much more effective would that same spacecraft be if it was 100 times faster?

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Typrix t1_iqwvpei wrote

10000 times more 'effective', if effectiveness correlates directly with energy.

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gulgin t1_iqxyhwu wrote

My favorite factoid about DART is that the impact was significantly more energetic than if they had literally made the entire impactor out of TNT, landed it on the asteroid and then blown it up.

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Override9636 t1_iqwwkm1 wrote

Kinetic energy = 0.5 * mass * velocity^2

So a 100x increase in velocity equals a 10,000x increase in kinetic energy.

(although it isn't that simple because the asteroids aren't perfectly solid objects and are more like loose collections of gravel.)

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fabulousmarco t1_iqwpo7y wrote

Essentially, they are saying that the test was successful but it is still only one data point.

The final aim of this research is to be able to know, in case an actually dangerous asteroid were on a collision trajectory with Earth, what kind of impact would be sufficient to knock it onto a safe course.

So we know the mass, trajectory and velocity of DART and soon we'll know the exact effect the impact had on Dimorphos, but what we don't know is the effect of Dimorphos's characteristics. What if DART had struck another asteroid with, for example, the same mass but denser? What if the asteroid had been composed of a different material?

By carefully analysing the impact site and the asteroid itself with follow-up missions (like HERA) we can try to determine the effect of Dimorphos's characteristics so that in the future we may more easily predict the effect of an impact on any asteroid, provided we have some data about it.

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