Sol's Shipbuilding Industry

[Corvus 501]

Look up

[Batman]

You're right, my bad.

[Corvus 501]

Thats ok, and the idea is that the "ships" (really more like missiles) drive right into the sun to burn up.

[Batman]

The problem isn't the dumping stuff into the sun. The problem is the effort you need to put into it.

[Formless]

Corvus, Sith Acolyte is a standard title that everyone gets once they accumulate a certain post count (just like your current title is "redshirt", and that goes away after about ten posts). Unless someone has a custom title, I suggest simply using usernames lest you cause confusion.

[Corvus 501]

Opps

[Simon_Jester]

...
And you DO have to cancel all of it, not just a little; otherwise the millions of tons of rocks will enter an elliptical orbit about the sun, with the aphelion at... pretty much wherever you dumped them from. In which case, thanks to Kepler's Third Law, we've now got a cloud of interplanetary buckshot which will come zooming through the general vicinity of Earth once a year, every year, as the anniversary of your stupidity.

emphasis mine

I love you.

I'm curious what "mine tailings" even means in space. Once you're outside a well, and moved into a relatively unoccupied orbit, structures can be made out of fairly weak materials so long as they have the ability to be repaired from micrometeorite impacts.

"Mine tailings" is a term I'm using for whatever bits of the asteroid(s) and comet(s) you decided not to use. Spacecraft are mostly going to be made out of metals, alloys of very specific compositions and with carefully chosen proportions of different chemical elements. No matter what form of native rock or other raw materials you extract those elements from, there's going to be leftovers. Odds are that the mass of the leftovers will exceed the mass of the rest of the asteroid.

Sure, you can use a lot of that otherwise useless rock as bulk filler for some kind of megascale structure, but there probably isn't much point in doing so if you ask me. There are few situations where wrapping your habitat in 500 meters of loose rock that's had all the useful metals extracted from it in an ore refinery will be more appealing than wrapping it in one meter of nickel-iron-plus-alloying-materials.

To Sith Devote: good points all, but the delta-v problem solves itself. The purpolsion system of the outbound forged metel freghters is a laser powered ion drive, one which uses ionised silaca gas as reaction mass. It's bascialy a cross between a solar powered ion drive, and a laser launch rocket system.
As to your piont about coolin the metel down, why don't you pitch your own idea? Mine is to spray it with gas liberated from cometary matiral, but I could use some new ideas there .

Look, kid, either learn to spell or go away. Really, how do you misspell "metal" as "metel" on either a QWERTY keyboard OR a smartphone?

More seriously, that does not solve the delta-v problem. The delta-v required to power a laser launch system just comes out of your electric bill instead of your kerosene/LOX budget or whatever.

Sure, in principle we can just ask "what if delta-v were essentially free even for purposes of hauling around obscenely heavy and useless heaps of random crap?" But in that case the answer to your overall question is: "Who cares, there aren't really any logical reasons to put any industry in any specific location, because energy is free for the taking everywhere you'd want it anyway."

Free energy makes it easier to dream up a solar system economy, sure... but it also makes it pointless to try, because you're trying to picture an economy that operates on the far side of a technological singularity.

[Terralthra]

Sure, you can use a lot of that otherwise useless rock as bulk filler for some kind of megascale structure, but there probably isn't much point in doing so if you ask me. There are few situations where wrapping your habitat in 500 meters of loose rock that's had all the useful metals extracted from it in an ore refinery will be more appealing than wrapping it in one meter of nickel-iron-plus-alloying-materials.

O'Neill Island IIIs are mostly constructed out of steel-backed concrete and reinforced glass. Carbon, silicon, with some iron for toughness. Just by using concrete, you've reduced "tailings" by a hell of a lot, given how many asteroids out there are carboniferous.

[Simon_Jester]

Hm. My main issue is that I have trouble picturing efficient concrete manufacture in a free-fall vacuum. Neither aggregate nor cement is going to be all that easy to work with under such conditions. I tend to visualize space-based structures as being either metallic or tunneled into massive, pre-existing rocks (asteroids and moons).

That doesn't mean I'm right to do so, though; do you have any references to ideas of concrete-making in space?

[Terralthra]

Hm. My main issue is that I have trouble picturing efficient concrete manufacture in a free-fall vacuum. Neither aggregate nor cement is going to be all that easy to work with under such conditions. I tend to visualize space-based structures as being either metallic or tunneled into massive, pre-existing rocks (asteroids and moons).

That doesn't mean I'm right to do so, though; do you have any references to ideas of concrete-making in space?

STS-68 (in 1994), see experiment 2.

Another more recent article here

[Simon_Jester]

The lunar concrete experiment doesn't feature microgravity- it's promising, but it doesn't address my concerns directly because the experiment appears not to have proceeded in a microgravity vacuum. Still awesome to know it's possible on the moon, though.

The STS-68 experiment does directly address at least half my concerns (concrete formation in microgravity). Having some trouble figuring out how that experiment went.

[Corvus 501]

Well, I suppose that you could spin the concreat factory to make up for zero gravaty.

[Simon_Jester]

That's trivial as long as you don't need the concrete to cure in place. Say, if you're just making concrete bricks and somehow cementing them together.

I'm not sure that's a safe way to build a large-scale space habitat, though.

[Sea Skimmer]

Roller compacted concrete will work if nothing else, make formwork, squish in layers of concrete with the roller as you fill it up. Making the cement in zero gee might be annoying though, but this will be true of many other materials too. I'd tend to expect metal construction too, with borated foam as the radiation shield and some measure of impact protection.

[Terralthra]

The lunar concrete experiment doesn't feature microgravity- it's promising, but it doesn't address my concerns directly because the experiment appears not to have proceeded in a microgravity vacuum. Still awesome to know it's possible on the moon, though.

The STS-68 experiment does directly address at least half my concerns (concrete formation in microgravity). Having some trouble figuring out how that experiment went.

The only non-paygated results I found easily from there were here, but it's not the most credible-looking source. Looks like a PowerPoint printed to PDF.

As for building it out of panels...why wouldn't that be a good way? For sure you'd want to make any large windows out of panels to contain any cracks to one panel. Why wouldn't the same apply to concrete fractures?

[Sea Skimmer]

Concrete is strongest when made in as large of pours as possible. Any place you have to join different pours becomes a fracture zone. On the other hand you shouldn't get much stress cracking with little or no gravity.

Thermal expansion will be the main limitation on the size of pours, but this could be avoided by installing an active cooling system and enough thermal insulation. A space structure far enough from the sun, or always on the light/day side of a planet ect.. wouldn't really have a significant thermal cycle on a daily basis. Any kind of internal heating or more likely refrigeration system would just need to be regulated to keep it an even temperature at all times.

Put a vapor barrier inside the concrete and that will at least reduce the chance of a pressure leak being a serious hazard. A thin welded metal liner would be really desirable though, since then you could also use it as an attachment for stuff and avoid drilling into the concrete constantly to mount equipment.