Author Topic: Our solar system is filled with asteroids that are particularly hard to destroy  (Read 3134 times)

Offline su27k

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https://thespacereview.com/article/4521/1

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A vast amount of rocks and other material are hurtling around our solar system as asteroids and comets. If one of these came towards us, could we successfully prevent the collision between an asteroid and Earth?

Well, maybe. But there appears to be one type of asteroid that might be particularly hard to destroy.

In our new study published last week in the Proceedings of the National Academy of Sciences, we discovered that rubble pile asteroids are an extremely resistant type of asteroid and hard to destroy by collision.



Paper: Rubble pile asteroids are forever

Quote from: Abstract
Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10 times longer than their monolith counterparts. We studied three regolith dust particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, atom probe tomography, and 40Ar/39Ar dating techniques. Our results show that the particles have only been affected by shock pressure of ca. 5 to 15 GPa. Two particles have 40Ar/39Ar ages of 4,219 35 and 4,149 41 My and when combined with thermal and diffusion models; these results constrain the formation age of the rubble pile structure to ≥4.2 billion years ago. Such a long survival time for an asteroid is attributed to the shock-absorbent nature of rubble pile material and suggests that rubble piles are hard to destroy once they are created. Our results suggest that rubble piles are probably more abundant in the asteroid belt than previously thought and provide constrain to help develop mitigation strategies to prevent asteroid collisions with Earth.

Offline Paul451

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https://thespacereview.com/article/4521/1
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If one of these came towards us, could we successfully prevent the collision between an asteroid and Earth?
Well, maybe. But there appears to be one type of asteroid that might be particularly hard to destroy.

[Not the point of the article, but...]

If an asteroid threatens Earth, you most likely don't want it to be "destroyed" (ie, broken up) unless it's so far before impact that nearly all the debris spreads wider than the impact trajectory and thus misses Earth. More likely, breaking up an approaching impactor will just turn it into scattershot with the same overall mass/energy hitting Earth, which might not be much of an improvement.

Rather, you want the asteroid to stay intact while you alter the velocity of the whole thing. It's better to think of these rubble-piles as the spring/dampener in an Orion-type nuclear pulse drive. The "ship" is still pushed along by the nuclear blasts, even though the dampener "absorbs" the shocks. The robustness of asteroids is good, because it means you don't have to be especially careful with the size of the series of nuclear detonations you are using to divert the asteroid, allowing you to trade around available warheads for conversion + available transport.

Comets are still an issue. We know they seem to differ wildly in composition and structure, and we know they have a tendency to break up.

Offline Mr. Scott

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Asteroid defense has been discussed many times.  The cliche of using nuclear blasts doesn't have a lot of certainty or practicality due to the weight of material needed to launch to really affect anything. 

There was a concept out of Japan a few years to use the Earth's magnetic field & van Allen radiation belts as a kind of storage volume for antiparticles.  If an asteroid approaches the Earth thru the radiation belts that is saturated with antiparticles - voila... your asteroid is gone.  But anything near the South Atlantic Anomaly will also be disintigrated, as well as portions of the moon, and a volume of satellites, and additional portions of Earth.  But the asteroid problem will be fixed.

Offline Phil Stooke

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I really admire the way you dismiss another idea as "doesn't have a lot of certainty or practicality " before launching into one of the most profoundly uncertain and impractical ideas it has ever been my privilege to witness.

Offline Harry Cover

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I really admire the way you dismiss another idea as "doesn't have a lot of certainty or practicality " before launching into one of the most profoundly uncertain and impractical ideas it has ever been my privilege to witness.

He is a well-known troll...

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