Does that calculation change if the goal is not to bring minerals back to earth, but to mine them and use them in situ to build habitats and the like? I imagine a bunch of sand and iron and ice would be quite useful in those circumstances

Isn't it cheaper to mine resources in space for space travel then to eject them from earths orbit. If we found an astroid that had water that'd be worth it to bring it to a space dock or to any habitat that doesn't have water (planet, spaceship, satellite).

I do agree the idea of bringing them back to Earth makes no sense, and the technology necessary to do that will probably make it not necessary thru other breakthroughs. But if you believe that Earth isn't the only location for humans to live we won't want to bring ML (Mega Liters) of water to future habitats, we want to either find it, or manufacture it.

Exactly. I highly doubt raw iron or other common metals will ever make sense to import from space, but there will almost definitely be a market for materials to be used in space or manufactured in microgravity that can't be done on Earth.

Maybe, but habitats that far out probably never work because the sun is so weak.

why is the sun required for habitats.. plants can grow in artificial sunlight....

generational ships could spend entire decades in pockets with no sun...

all you need is the right raw materials, access to water and food, and fuel source to keep the uv lights working and the heater and oxygen pumping...

The energy source is the hard part. The sun will work for millions more years. Will fusion reactors work that long without some random failure of some part? Would you bet your life on it?

mirrors work forever in space

You don't need the sun when you have nuclear fusion.

or mirrors

Energy costs are small if you aren't in a hurry. See [1], and for more detail [2].

[1] https://en.wikipedia.org/wiki/Interplanetary_Transport_Netwo...

[2] http://www.dept.aoe.vt.edu/~sdross/papers/LoMarsden-Feature....

That doesnt make sense. Rockets that go slow take much less fuel, especially when starting and ending in zero gravity.

And if you move the manufacturing to a space station or small moon, you could move trillions worth of material for thousands in fuel.

This ignores the potential to build stuff in space, which would create a market for metals, like say aluminum. Sure aluminum is cheap on earth, but the delivery fees to space are $$$$.

This article also seems to have a basic misunderstanding how travel in space works. You spend energy to accelerate/deaccelerate in space, you don't pay per meter like you do in the atmosphere. So once in the asteroid belt you can reach any other point in the asteroid belt with very little fuel, if you are patient.

A mine to the Earth’s core would be exceedingly rich. Such a mine would be impractical, given the large amount of planet to be bored through.

A large amount of space is more easily traversed. Core material from shattered proto-planets exist in the asteroid belt, unsurrounded by planet. It’s as if some heavenly hammer cracked the thick egg crust imprisoning a cosmic platinate egg, and left that creamy yolk of gooooold for us.

To you as a jeweler in New York City, this is perhaps irrelevant. You’re neither digging to the center of the planet nor are you flying in space.

But people do fly in space. They might need metal and lots of it, some day.

Asteroids are quite varied in composition; it doesn't matter what most are.

There are slow low energy ways to get around the solar system by using the Lagrange points in the orbits of various planets/moons. Large amounts of refined minerals could be distributed this way assuming a solar powered refinery on a large asteroid or even just parked in space.