[imglorp]

Is this assuming some of the materials are available there? This would make sense if you're getting fuel or metal from asteroids, moon's surface, etc and building ships near those. But in Earth orbit, you'll need to lift the shipyard, then the fuel, then the metal powder etc for sintering, so what would be the gain?

[mattlondon]

You could construct things that wouldn't fit inside the nosecone of a launch rocket if you assemble them in orbit.

You could also repair/refit things without them having to go through re-entry and then be launched a second time E.g. replace damaged/worn out rocket cones or solar panels etc if you can build them in-situ. Imagine Earth-Mars shuttles that just go back and forth that would need maintenance

[adrianN]

Lifting many small things is easier than lifting one Battlestar Galactica sized thing.

[jacquesm]

Also, if it goes wrong the damage is limited, and likely fixable.

[mkl]

Yes, you'd probably want to go get some asteroids. Even small ones can contain huge amounts of metals, and icy ones could be turned into fuel. There's a lot of potential, but it's all a bit out of reach for the moment. https://en.wikipedia.org/wiki/Asteroid_mining

[HeyLaughingBoy]

Still, the concept of space mining is slowly becoming a thing: https://space.mines.edu/

[JoeAltmaier]

Isn't moon dust mostly bauxite? (oxidized aluminum)

[mkl]

Not exactly https://en.wikipedia.org/wiki/Geology_of_the_Moon. I think the problem with moon resources is the moon's gravity while forming was strong enough to pull metals like iron and nickel down into the centre where we can't get at them (they're on the surface a bit too, but not conveniently concentrated). Asteroids, on the other hand, can contain lots of accessible nickel, iron, cobalt, etc.

I'm no expert though!

[ben_w]

Wikipedia looks like it says [0], by elemental concentration, roughly 42% oxygen, 21% silicon, 12% iron, 8% calcium, 7% aluminium, 6% magnesium, 4% other.

[0] Bar graph with insufficient labels: https://en.m.wikipedia.org/wiki/File:Composition_of_lunar_so...

[imglorp]

Magnesium should be even better for some space apps. In fact, it would sinter better in a vacuum than air.

https://www.deepdyve.com/lp/wiley/sintering-of-magnesium-h06...