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Comment by zitterbewegung | Hacker News Reader

There are two flaws with this. One is that if something breaks that can't be manufactured with a 3d printer. (Solar panel, processor, gyroscope) The other thing that would be a problem is that you are just shifting it over to what the 3d printer uses as building material. Even if you put a stockpile up there it may still run out.

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Yes, it's not a panacea. But it's a heck of a lot easier to store a generic supply of printer feedstock, than to store one (or more) of every part that might conceivably break.

Suppose that you expect 1% of all replaceable parts to break over some projected lifespan. Then the mass of feedstock required would be 1% of the mass of the replacement parts... and would take up less than 1% of the space.

Ah, good point.

I was thinking that if you are bothering to ship up the feedstock why not just ship the spare parts themselves? But you are right, this would reduce the total mass they needed to lift to orbit.

For the second problem, the solution is to recycle the broken part back into the building material. This problem is being worked on by some in the RepRap community (sorry, no time to look up the link).

https://reprapdelft.wordpress.com/

And what if the 3D printer breaks?! They'll need a 3D printer printer. ;)

There actually are a bunch of 3D printers that print most of their own parts!

Imagine a RepRap with NASA/RKA attention!

This is what I was going to say. They'll need 2 3D printers so if one breaks the other can print replacement parts for it.

"Machines building machines, how perverse".

Well, if we had little robots to run the 3D printers anyway.

I never did get that quote. After all, that's what car factories do...

Oh well, I guess it was a shit movie to begin with.

The idea is to dramatically reduce the cost, not bring the cost to zero. I agree that the idea that we will be able to keep ISS in space infinitely with this technology is doubtful though.

ISS needs some fuel to combat atmospheric drag every once in a while, too.

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