Manufacturing stuff in space

So I was watching one of those programs on television about near earth asteroids and life on earth being devistated by one in the unknown future.
I started to fantasize about an alternative to blowing one up, or redirecting .......wouldn't it be resourceful to find a way land on it, set up a factory , and make stuff out of it? From what I hear, asteroids are made up from metals---so it would be neat to put a foundry on/around it, nibble it up, and turn it into a bunch of steel parts.

Of course, anyone planning to do something like this would be faced with the daunting task of trying to manufacture stuff in space....which is the question I have for this thread.


I would like to know what are some of the specific problems a space factory would encounter?

 

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Well, I'd say the biggest one would obviously be cost. The cost of fuel and equipment to GET there, the cost of being able to transport enough food, water and oxygen for just a small crew of two or three.

Ultimately, I believe you'd wind up with THE most expensive steel parts ever!!! Something on the order of thousands of dollars per ounce of finished steel.

 

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Other than being built on an asteroid destined to go crashing into the Earth at some undisclosed point in the future?

You'd be looking at setting up on a relatively fast rotating body - that means massive extremes in temperature between night and day - roasting for several hours one minute, freezing you're cods off the next. Not much different between being in orbit around the Earth really except without the protection of the Earths magnetosphere - you're exposure to lethal solar radiation outside that is immense. I suppose if you built under the surface you'd be safe enough.

Your major problems here wouldn't really be in setting up and refining, its really the whole business of navigating within an asteroid field that would provide you with your greatest challenge. Near Earth bodies such as these form unpredictable patterns of motion - they tumble around, collide, knock the nearest neighbours out of alignment - if you're set up on one not only do you have to contend with the likelihood of collision you've also got to ferry crew and equipment plus refined materials back and forth between your refinery and Earth. What starts off as a commercially viable operation could be rendered virtually inoperable without a moments notice.

That'd be your major technical problem - keeping a field clear enough to run a commercial shipping operation through it. Be a bastard to get insured, that goes without saying.

 

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This has been suggested for a long time. There are pure nickel-iron mega-mountains out there. However, Light is correct that the current cost would be hugely un-economical.

But in the future, when humans find a more economical way into space in order to colonize the solar system, metal asteroids would then be far cheaper than bringing metal from earth.

 

I'd have to disagree Mr A, with that conclusion. Asteroids, even in the thick of the "asteroid belt" (more of a region) are on average hundreds of thousands to millions of kilometers apart and rarely collide, despite the star-wars depiction of dense asteroid fields.

 

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... Well, I wasn't quite thinking of setting up over Geonosis, just basically thinking of what its like simply living here - the Earths continually running into the paths of meteorites, all shapes all sizes. Most no larger than pebbles, some as big as Volkswagens - large Asteroid sized bodies we can track pretty well, I'm thinking more in terms of the rest of the stuff running in amongst that - pebbles, lumps of 97% silicate no bigger than a garden gnome. We take pains to avoid running into icebergs here on Earth, not everything that's rolling around out there's a Extinction Level Event waiting to happen, is it?

 

Well, no.

But the general environment is not much different than around here. Most of the large objects in the asteroid belt share the same orbital parameters as you'd expect. The other objects that are on eccentric orbits (cometary debris, etc...) are no more prevalent in the asteroid belt than around here. Righto?

 

during the apollo years it was suggested to use the saturn second stage as a habitate
why they never followed through is anyones guess

 

What was SkyLab?
Ah, I just checked. It was the third stage of a Saturn V.

 

Mr A is partly right. Even though there arent tons of asteroids smashing into each other every second, there are alot of particles... far more than other interplanetary space. Lets just say that a nickle sized rock carreening at insane speeds hits you... yeah, its going to hurt.

So there is alot of fine particles that are whipping around out there. Earth is protected because we have an atmosphere in which to vaporize all that junk.

P.S. (Have you seen what a paintchip, traveling at 17,000mph, can do to a spacecraft in orbit?

From: http://www.bbc.co.uk/science/space/solarsystem/earth/spacejunk.shtml
"# A 1mm metal chip could do as much damage as a .22-caliber long rifle bullet

Bits this size don't generally pose a large threat to spacecraft, but can erode more sensitive surfaces and disrupt missions.

# A pea-sized ball moving this fast is as dangerous as a 400-lb safe travelling at 60 mph

Debris this large may penetrate a spacecraft. If this happens through a critical component, such as the flight computer or propellant tank, this could be fatal. ")

 

Well, let me put it this way. I'll put on the kettle, you fly the ship. Come back in one piece I'll even throw in some battenberg - how much more giving can a chap possibly get?

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my bad
it was indeed the 3rd stage

edit
i keep getting these mixed up
what i am refering to here is the stage that housed the LEM

they figured as long as they were crashing them into the moon that they could salvage most of it for bases
but like i said they never followed through with it

 

Deal.

 

Ok. All that matters is relative speed. Does a paint chip that shares the same orbit as a spacecraft pose a threat? No. In the asteroid belt, except for debris from comets on wildly different orbits, the objects all share the same orbital properties, otherwise they would have been "filtered out" by collision long ago.

Having said that, I agree that the debris that does not share the same orbital properties poses a not-insignificant threat. This is just one of many challenges to occupying an asteroid, solar and cosmic radiation being a worse threat by far.

 

I'll put the kettle on then....

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I think the tradeoff comes from the fact that the manufacturer could potentially build gigantic things without having to worry about hauling it from the surface of planet earth. This would come in handy if the factory was building something enormous like (for example) a new spaceship the size of an aircraft carrier.



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One of the biggest problems I'm wondering about is how to pour a mold in zero/reduced gravity. Also, is oxygen needed to weld steel pieces together?

 

two solutions come to mind
one could be compressed air to help fill the molds, another would be a giant centrifuge

as far a needing oxygen to weld
why would you need oxygen?
you aren't burning the metal you are melting it

the sparks you see from welding come from the electric current used to melt the metal

 

Imagine sending many nanorobots that will use trapped gases and solar energy to construct a spaceship out of a moving comet, so by the time the comet does a turn around the sun, it (comet) turns into a spaceship.

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I say...its neat...its doible

Also to make a mold in space its not that hard...and no u dont need a giant centrifuge...u can make a small centrifuge rotate real fast.

 

Comets have a huge amount of potential / kinetic energy. Your spaceship would have to overcome that. Earth crossing asteroids would probably be a better source of material.

 

I am not saying to send spaceship to comet. I am saying to sent trillions nanorobots to a comet, those nanorobots can be "shot" the right direction just like the probes are sent, these nanorobots will catch up to comet trajectory just at the right speed so they dont crash and make a soft landing and then they will begin to work in cooperation by first forming factories out of themselves and using the energy of gas molecules trapped in the comet to do this as well as energy of the sun, the factories will then begin to descrete unwanted material into space and melt metal right on the moving comet by making specific shape of a spaceship, some of the same exact gas trapped in that comet will be utilized in part of that comet and will be the future fuel container...The comet doesnt need to stop...all the job will be done right there.