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The reality of asteroids

Brian G Turner

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Phil Plait does a good write-up of rubble asteroids, and in the process explains why asteroids in general nothing like what we've grown up expecting them to be like from sci-fi: What astronomers mean by 'rubble pile asteroids'

Hopefully some of our science fiction writers will start using this sort of information in their own books. :)

Note: It also means the futuristic idea of mining asteroids for minerals might be somewhat flawed!
 

Vertigo

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Phil Plait does a good write-up of rubble asteroids, and in the process explains why asteroids in general nothing like what we've grown up expecting them to be like from sci-fi: What astronomers mean by 'rubble pile asteroids'

Hopefully some of our science fiction writers will start using this sort of information in their own books. :)

Note: It also means the futuristic idea of mining asteroids for minerals might be somewhat flawed!
Possibly the way such mining is described might be flawed but I think, if correct, this would actually make mining easier. Your asteroid has already been conveniently broken up for you making it much easier to extract the stuff you want.
 

Brian G Turner

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True, but it's not going to be easy sticking a colony on the surface, or digging caves into them, like in traditional SF. :)
 

Vertigo

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True, but it's not going to be easy sticking a colony on the surface, or digging caves into them, like in traditional SF. :)
True although even that might be made easier. Easier to burrow in, with no significant gravity to make your 'burrow collapse' and then seal it with some equivalent of the spray on concrete we use on terrestrial tunnels. So it could actually be easier to create 'caverns' inside them. However I guess you couldn't give them any significant spin without them breaking up; centrifugal force overcoming the pathetic gravity.

Might make using hollowed out asteroids a bit less viable for 'generation ships.'

I wonder if you could use large reflectors to concentrate the sun and, using mirrors, actually fuse the inside of the tunnels/caverns?
 

Venusian Broon

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True, but it's not going to be easy sticking a colony on the surface, or digging caves into them, like in traditional SF. :)
I always thought of the idea that 'space miners' would dig into them like miners on earth was ridiculous :)

You'd at the very least want to break them up and feed them to some sort of massive processer that could break it down into it's constituent components. Like strip mining it till it's gone. I mean you're not really wanting to keep the asteroid. And you'd probably want to go for relatively small ones, say the size of mountains. Which will have very little gravity. Thus it's easy moving volumes of stuff about.

A solid metallic asteroid might actually be too difficult for us in the medium term to actually hang on to and mine, as the article states, so these rubble pile ones might be easier. Plus you're really wanting to be refining it to get little volumes of precious material to send back to earth, while everything else, say water, carbon, silicon and nickel/iron, could be refined but sent to some sort of manufacturing plant in space, as it should cost less to have these from an asteroid rather than lifted up from the Earth's gravity well.

Here's a nice discussion of some of the issues:

 

Venusian Broon

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Might make using hollowed out asteroids a bit less viable for 'generation ships.'
Rather than hollow them out, use the materials that you can't send to market to make a frame around it (as the video by Isaac Arthur above discusses) and convert it all into a habitat/ship. Eventually. He argues that you probably want to go for reasonably small asteroids, not big ones with significant gravity.
 
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