Are you not aware that a you'd need ROOM for the stuff?

Are you aware that the amount of retrieved ore would not likely take up so much space?

What happens when it starts into the earth's atmosphere?

If it's in a return device with a Thermal Protection System, it reenters the atmosphere just like the Apollo capsules. Then it can be picked up by ships (if in the ocean) or by trucks (if on land). Simple.

Yes of course it has to be refined in space. Sending up unmanned fetching drones from the earth each trip would costwise negate any profits that could be made.

Sending any mass at all from the earth's surface to low earth orbit is extremely costly. But once it's in the zero gravity enviroment transportation between one point in 0 g to another point in 0 g takes considerably less effort and energy due to the almost entirely frictionless enviroment.

Compare throwing a baseball here on earth. How far could you throw it? 100 meters more or less until earth's gravity along with air resistance impedes the energy of the baseball and it lands on the ground. In space and far away enough from strong gravitic fields you could feasibly throw the same baseball all the way to the sun with just one throw (so long as the baseball doesn't hit anything on it's way there).

That's the main argument for mining asteroids. It's more energy efficient to transport large masses of matter vast distances than it is inside a strong gravitic field and other sources of friction. And where there's greater energy efficiency, there's costs to be cut.

And yes of course you have to get the refinery into outer space or low earth orbit piece by piece. How do you think they built the MIR or the ISS? And I said from the start that the downpayment for such a project would cost enormous sums. But once it's up there it could very well pay out in the long term (due to the vastly increased energy efficiency in transporting the ore).

Keeping a crawler up and running on mars is a lot more difficult than moving from one point in space to another. Mars has weatherstorms, is struck often by meteorites and other complications hard to foresee, and hat's not even counting the problems of running anything over the surface of Mars itself (wheels running stuck in ditches etc.). Moving from point A to point B in space is just a matter of mathematically calculating the wo points relative positions to eachother and adjust the bearing with the propulsion system (depending on how exact it must be of course).

We're basically flying both helicopters and jet fighters by remote control already (it's called "fly-by-wire"). If modern jet fighters going in speeds of MACH 3 were completely controlled by the pilot then they would crash and burn due to the enormous amounts of minute corrections and compensations in steering the aircraft that the pilot would have to make (well beyong human capabilities in terms of reaction speed). So the pilot is basically controlling the airplane with a joystick, telling the plane's computer system that is doing the actual steering in which direction the pilot wants to go and at what speed.

If the technology is availble to build a complex set of avionics like that, getting an unmanned craft from one point in outer space to another would be a walk in the park in comparison, since you barely have to correct heading since there are few forces of fiction to interfere with it as there are inside an atmosphere with air resistance and a strong gravitic field.

So no, it's not a piece of science fiction. The needed technology is already here and would only need minor tweaks to perform as needed.

The only real obstacle is the large costs in sending that much tonnage of equipment out into space to start up the operation. But once there it could mine a lot more efficiently than current earthbound methods allow for.

We're not running out of any minerals that I know of...

You haven't been watching very closely then. Given the current rate of population growth, we're set to start running short on critical industrial metals in about 10-15 years. It's even worse when you consider that a lot of the metals we'll need are required for energy sources which don't run on petroleum or coal (ie: lanthanides, platinum group metals, cobalt, etc). Then, of course, there's copper, which is already starting to show signs of playing out. When those metals start disappearing, our standard of living will plummet.

Not only would my solution solve that problem for some time, it would jumpstart space development and create very well paying jobs. Sitting on our thumbs will have the opposite effect.

Oil? Maybe that's one, but we already need another fuel anyhow.

We have uranium, which would easily replace our demands for fossil fuels. Of course, getting a large source of nuclear fuel would help make the power even cheaper, and there are uranium and thorium ores on the lunar surface. Easy source of fuel.