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Comment by QAPereo | Hacker News Reader

It might cost more, but it’s certainly abundant; we’re not going to run out of it. No I would even go so far as to say that a rise in the price of terrestrial lithium would be a good thing. In the short term it will hurt, but there’s a lot of runway in that graph before we hit serious scarcity. As the price rises I could honestly see someone like Elon Musk or Jeff Bezos finally astroid money off the ground. I don’t have much hope for Mars in our lives, but asteroid mining absolutely could happen.

This could be a safe source of pressure, partly political if people realize it will be easier to move in space than Afghanistan, to make that happen. For those of us you dreaming of a future for the species beyond Earth, I think this might be the realistic start.

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Lithium can be extracted from the ocean at commercially viable costs, no asteroid mining required.

Correct! However, since lithium is abundant, there are so many other cheaper sources of lithium (for instance, geothermal brines) that ocean extraction will never be the cheapest source (although it is sufficiently cheap if it were the only option).

At what environmental cost? How many gallons/sec are you processing, how much energy is used per gram of Li? Without burning fissile fuels or building expensive new nuke plants, how will it work?

mining asteroids in our lifetimes would primarily be useful for harvesting raw materials for constructing things in space, not sending the materials back down to earth.

Either will require a breakthrough in propulsion systems.

Not necessarily. In the near term, mining asteroids means mining near-Earth asteroids, not those from the belt.

The changes we'll need to make to propulsion systems are more about their operations - we need more types of engines that can be frequently shut down and restarted.

Isn't sending things back to earth relatively inexpensive? Wouldn't gravity do most of the work?

You need to first send equipment to do the mining and sending back - that part is very expensive, and if it's only to be used for sending stuff back to Earth (safely), then mining in space has very bad returns.

Asteroid mining is absolutely awesome if you move as much of the process as possible to space - every kilogram you use up there to build something is a kilogram you didn't have to launch upwell.

What you'd really want to do is develop a working zero (natural) gravity solar-furnace process that works.

It'd probably involve some kind of centrifuge design... but I wouldn't rule out just making something screaming hot and then suddenly introducing kinetic energy.

Then there are two main options...

A) Make a crude re-entry shield out of the waste products + some of those other resources you're not keen on harvesting for the primary use of sending to earth, and you put a nice candy core in the middle. Aim the landing trajectory at some shallow ocean.

B) Taking things UP in to orbit is expensive. Taking them back down is probably less so, though our current vehicles aren't based on completing that task so they'd need to changed to handle cargo both ways.

Option C could also be fun... if we ever get space elevators working things could go a lot like in science fiction. (The orbital elevators and start of a planetary ring from Gundam 00 jumps to mind as a reference; 3001 also had the idea much earlier but in less detail)

You've got to find a way to go from over 20,000k per second to stationary on the ground. For any worthwhile mass of asteroid you bring back to Earth, it's going to require one hell of a heat shield during reentry.

So maybe you leave the heat shield in orbit, but you've still got get it there.

I think space mining becomes possible when you're no longer cornered by the rocket equation. That is, it's going to require a breakthrough in propulsion systems.

> I think space mining becomes possible when you're no longer cornered by the rocket equation. That is, it's going to require a breakthrough in propulsion systems.

I think near-Earth space mining and manufacturing is what can help us get over that limit in some way - LEO is halfway to anywhere in the Solar System ∆v-wise, so whatever part of your mission you don't have to lift upwell makes for huge savings in fuel (and for many missions, you can use weaker and more efficient engines once you're on a stable orbit).

I imagine that platinum will be the most important metal mined from asteroids and returned to Earth. Thick platinum shielding should hold up well on atmospheric entry.

It may be useful for some raw materials - for example, osmium ($13,000/kg), rhenium ($2,750/kg), and iridium ($30,000/kg). All three of those are elements that are probably common in the Earth's mantle, but nowhere near the surface, and are mostly found in meteorites; all of them are used in high-performance alloys (high-temperature, corrosion-resistant, etc.)

Doubling the world production of any of these would greatly reduce the prices of aerospace engines and electronics (iridium is used for crucibles growing high-quality semiconductor crystals). And that's easy, because the quantities involved are so low - under 1 ton of osmium per year, 10 tons of iridium, and 40 tons of rhenium.

There are other materials like that. It's all about searching for the competitive advantage, the materials that can't be found on Earth in reasonable quantities. All the nickel and iron and titanium will indeed probably stay up for in-space use.

> It may be useful for some raw materials - for example, osmium ($13,000/kg), rhenium ($2,750/kg), and iridium ($30,000/kg).

Or tungsten, in the form of cylinders 6m long and 30cm in radius, transported gravitationally to their place of use.

Rods from God?

Yep.

https://en.wikipedia.org/wiki/Kinetic_bombardment#Project_Th...

Those sabots better land where they are supposed to!

The price would probably collapse unless we find a huge market for it

That really depends on the assumptions you’re making about why it’s done. Large scale mining for building materials and fuel requires an existing space industry for demand. Saving on Dv only makes sense if you have something proven so out there... like mining. Either way there needs to be a truly enormous initial investment in propulsion, and so much more. Making an absolute fortune, and/or breaking foreign control over vital resources could be the key to getting that funding.

I don't see how asteroid mining can be viable economically. You still need an enormous quantity of petrol to send things in space and judging by the rarefaction of said petrol its price is bound to increase a lot.

> You still need an enormous quantity of petrol to send things in space

You need to think out of that box - I'm investing my savings in hevea plantations !

Cryogenic engines burn hydrogen from electrolysis and their fuel can be produced from renewable resources. All their atmospheric fuel is returned to the ocean by the water cycle, so little fuel is lost to the vacuum. Engine tuning limits greenhouse emissions. Magnetic projectiles can reach escape velocity with the right design.

Instead of one giant rocket, imagine swarms of small, reusable, low-emission projectiles whose payloads assemble into larger apparatuses in space.

It's irresponsible to say that you want something to become absolutely more expensive just so some other amusing method of production becomes comparatively less expensive. The idea behind solving problems is to make life better, not make live hard so it can be made almost as good as before.

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