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Mission: Hayabusa 2
post Today, 03:09 AM
Post #601


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Joined: 17-April 10
From: Kamakura, Japan
Member No.: 5323

Something has been bothering me a lot. It is as follows.

If an asteroid is made of hard metal and somewhow it is covered with sands and pebbles and rocks and if someting collides with it very
hard resulting schock wave must be cataclysmic to shake them beyond escape velocity, leaving nothing but the metal asteroid.

Craters on Ryugu seem to suggest that Ryugu is like a metal, soft metal, soft enough to leave crater holes but hard enough not to break
up on impact. So, why are there regolith and boulders still left on Ryugu? Where did those boulders come from in the first place?

I am trying to persuade myself that those shaken off Ryugu travelled into deep space and came back to where they started from after
billions of years in the solar system. Am I going mad?

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post Today, 03:29 AM
Post #602

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Joined: 13-February 10
From: Ontario
Member No.: 5221

There's probably no metal at all in Ryugu, it's more of a 'rubble pile', of low density rocks (just like Itokawa), with many voids and empty spaces inside. I'd guess the inside is as broken and fractured as the surface the cameras can show us.
The craters we see are all very soft, with rounded edges, and every impact just breaks off more pieces, which either don't have enough velocity to escape and come back as boulders (I'd guess the enormous one at the pole is one), or, if they have enough velocity, fly off as separate bodies, permanently. The ones we see now were all probably part of the original body when it first broke off in turn from its parent body eons ago, and have just been broken up and reformed, probably many times since.

The impact projectile Hayabusa 2 is carrying is the perfect experiment to demonstrate this when they fire it at Ryugu. It should replicate the natural process on a smaller scale.
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