How efficient is iron smelting ?
I love the idea of great hunks of metal crashing to Earth. I really wouldn't want an accident though. To make it economical, you'd need some permanent facility on the mining site that could produce the small rockets needed to send each chunk back to Earth, as automated as possible. That would make each chunk essentially free. Of course, you'd need a few people on site to make sure everything runs smoothly. But once it's all set up, running costs should be very low indeed.
Practical ideas to establish a large-scale moon infrastructure are few and far between. I don't think I could name one besides Orion, so I'd be very interested to here others. You can email me at rhysyatplexersoft.com.
As for NASA and its funding sources, I agree entirely. There were recent reccomendations that it should concentrate on establishing a space industry and utilize the private sector far more. In principle this means a partnership between the government and private companies - great ! Unfortunately in current practise - the CEV development - it means putting so much paperwork on the private companies that only the very largest can get anything done at all. So unless NASA decides for a radical overhaul, it's more likely the private sector will lead the way.
b1ueshift : If you wanted to just take up one ship, do some mining and come home again, the only practical method is an Orion. Has something like $200 per kilo of payload fuel costs. I think it would make much more economic sense to establish a facility at the other end that can send materials back though. That might be practical even with puny chemical rockets, though nuclear rockets would be better. (for an Orion, the vehicle mass to payload mass is about 3:1 for a Mars shot, or of that order. Waaaay better than a Saturn - enough to establish the inital base at a cheap level)
Just to emphasise, I'm more interesting in just keeping the colony going. Profit-making isn't a concern. They only need metal to make equipment for them to live and explore. The cost to do this for Earth is zero, after inital expense, if they manufacture all their requirments in situ.
Back to the iron smelting, I forgot they'll need carbon if they want to make steel. That allows them to make up to to 15,000 tonnes of high-carbon steel per year, if all they use for carbon is plants. I wonder if CO2 can be broken down by a more efficient process than using it as plant food ?
Making other steels would require other materials like tungsten. I think they're only present in small amounts. They'd have to get buy with what they started until the colony was sufficiently large to be able to process large volumes of material to extract the trace metals.