We don’t need large centrifuges for casting. Small ones are good enough. They are used even in Earth gravity where it is not sufficient (higher-melting metals typically have high surface tension and need a bit of help to get to the mold; a long neck to use hydrostatic pressure is one variant, but spin-casting is another popular one).
Zero-g can have quite some advantages. Many materials, including metals, are diamagnetic, therefore they can be pushed around with magnetic fields. Youtube has demos with pieces of e.g. bismuth or other stuff on a string, or on a paper boat on water. Or you can buy kits with little pieces of pyrolytic carbon levitating above magnets, At zero-g, the metal can be melted with a lens, the liquid glob insulated with the vacuum then pushed around to the ingot mould, the mould spun up and down (two counterrotating ones can be used to avoid reaction force to the rest of the satellite, the ingots cool down while the mold spins by conductive heat transfer to the mold (which then loses heat by radiation into space during the next melting cycle). Regenerative braking can be used to retrieve most of the energy needed to spin the mould up.
For sintering from lunar regolith, see the experiment done with Fresnel lens and a desert sand. Youtube has more videos of melting sand and rock with a lens.
Presumably ‘us’ means US?
I expect China to be there within a few years.
Out of the bunch of authors here, why do we only hear about Doctorow in this post? I’m sure he can be trusted to generate a handful or more of posts about his writing in this upcoming book.
Probably a Tardis!
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I couldn’t agree more with the sentiments of this article. We shouldn’t limit ourselves to the notion that this somehow requires government when the accessibility of robotics now affords possibilities for space development as community ventures. I see the Moon as potentially the greatest model train train layout ever, the kind the whole world can participate in. For the past couple of years I’ve been trying to cultivate interest in telebase development as the basis of an open space program built on a Linux development model. A true global people’s space program. But, alas the space advocacy community has proven to have a hard time with this concept. Without the immediate promise of a seat in Captain Kirk’s chair there’s little interest.
Not in our lifetime. There’s too much evidence up there of America’s not actually having been in the first place. Are you kidding me, that I can’t see a live picture in HD of the rover and the other stuff they left there. It’s been 45 years. I think you’ll find that NASA has a very strong interest in ensuring that nobody goes anywhere near the moon until the cold war farce that was Apollo is several more generations behind us.
Here’s the question I would ask: What would you do once you got to the moon? Collect more rocks? We already did that. The reason we have not been back is there is that it is a big dead rock and there isn’t anything we would do once there that requires a person.
The thing is, “America never went to the moon” is basically a non-falsifiable hypothesis. If you already choose to reject all the existing evidence that the Apollo moon landings were real then a live video feed wouldn’t make one lick of difference.
If NASA had the ability to fake the original landings with 1960s technology (even convincing our cold war enemies of the feat), then a little HD video footage in 2014 would be a piece of cake by comparison.
We have technology. We lack a reason to justify the cost.
We went the first time based on a cold war, our-rocket-is bigger-than-your-rocket basis. Going back is hard to justify because it is expensive to reach, there are no economic motives and the moon is poor in the resources needed for permanent settlement.
It is actually cheaper to land payloads on Mars than the moon and the environment is (relatively) more benign. (Getting back is harder.) I would wager that Mars is a more likely human destination than the Moon, especially for settlement.
They’re going to have to increase their hacking efforts into NASA a little to achieve that.