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Landing on an a asteroid might cause an avalanche?!

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Fri, 2013-07-05 16:31

Arenamontanus Arenamontanus's picture

Landing on an a asteroid might cause an avalanche?!

http://www.networkworld.com/community/blog/landing-asteroid-might-cause-... http://mnras.oxfordjournals.org/content/early/2013/05/27/mnras.stt742.ab... Basically, some asteroids might be very fluffy and unstable rubble piles. Fun opportunity to get the PCs to roll REF...

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Sun, 2013-07-07 03:08

OneTrikPony OneTrikPony's picture

I don't understand why they

I don't understand why they used beads of uniform size. It seems to me that they should have looked at non uniform sizes and shapes to study how these aggregate bodies form and evolve. Perhaps that will be a future experiment. I deal with aggregates quite often at work, from native soil, to engineered fill, to road base, to various concretes. The size and shape of the particles has a very large effect on the mechanical properties of the whole. People who don't make a living dealing with dirt can get a sense of this by imagining dipping their hand into a bowl of marbles or grain verses dipping their hand into a bowl of sand, gravel, and small irregular stones. With a little bit of vibration to remove air and "densify" (sigh: that's an industry term) the aggregate materials, the conglomeration can have very impressive compression and sheer strengths. I suspect that this concern is akin to the concerns about 'swimming through dust' on the moon before Armstrong actually walked there.

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Mea Culpa: My mode of speech can make others feel uninvited to argue or participate. This is the EXACT opposite of what I intend when I post.

Fri, 2013-07-12 03:34

Arenamontanus Arenamontanus's picture

I think the issue is separate

I think the issue is separate from the "swimming through the dust" issue (which did produce Clarke's memorable "A fall of moondust") - especially since the gravity is so weak that dust tends to fly away into a slowly orbiting mist. From what I understand of the science of granular media (the cool offspring of soil mechanics, now free from the dirt and equipped with neat computer simulations and lab experiments with glass microspheres) those force chains can behave in really odd ways. The size distribution certainly influences what behavior they have, but it would not surprise me that you could get serious instabilities when you have extreme loose packing in microgravity. Just consider dry quicksand: http://vimeo.com/63471076 - that stuff is still packed by gravity. Now imagine piling it up on top of a gravel pile at a crazy angle in a rotating reference frame. Then imagine the heavy synthmorph running from cover as it is pursued by an irate neo-gorilla with a plasma gun...

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Sat, 2013-07-13 00:49

DivineWrath DivineWrath's picture

Well the dry quick sand, if

Well the dry quick sand, if discovered (maybe by be fallen into it) at the right time under the right circumstances might work well as a good hiding spot. However, that would largely depend on how well the irate gorilla knows asteroid geology (and hope its muse isn't much better).

Sat, 2013-07-13 03:36

Arenamontanus Arenamontanus's picture

DivineWrath wrote:Well the

DivineWrath wrote:
Well the dry quick sand, if discovered (maybe by be fallen into it) at the right time under the right circumstances might work well as a good hiding spot. However, that would largely depend on how well the irate gorilla knows asteroid geology (and hope its muse isn't much better).

Heh. Didn't think of it. And the best part is, when I wrote the post above I was thinking of a signature gorilla NPC I use... who actually is pretty likely to know asteroid geology. "But you are a plasma-gun wielding gorilla! You wrecked the shuttle!" "That, sir, doesn't mean I didn't go to university and graduated summa cum laude."

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