You’d have had to be living under that oft-mentioned internet-proof rock (or possibly just focussing on that other currently ubiquitous news topic) to not have noticed that yesterday’s launch and re-entry of SpaceX’s Dragon capsule went off exactly according to plan. So when – if? – the Wikiwars die down a bit, expect a lot of pondering from all sides about the future of commercial space exploration, unfettered (well, kind of… or rather not really) by the capricious politics and budgeting of nation-states. Hell knows I’ll be waffling about it a fair bit… but then you probably knew that already.
The sceptical among you may be wondering what’s going to convince profit-motivated businesses to clamber up the gravity well. Well, Centauri Dreams has a pretty good run-through of a paper entitled “Space Colonization: A Study of Supply and Demand”, which suggests that there may well be gold platinum in them thar lunar hills…
Lunar prospecting, then, is a first step in determining the existence of asteroidal metal containing nickel, cobalt and platinum-group metals on the surface. We have much to learn, including not just the quality and location of ores, but also the location of volatiles like water. We also need to learn what happens when asteroidal nickel/iron is made into metal products, and to what extent we will have to rely on engineered alloys to get the desired result. At present, of course, we cannot test the processes we might use on the lunar surface, requiring a preliminary manned base there to work through these contingencies.
Andrews works out a simple cost model exploring mining, processing and shipping operations, comparing these to existing costs. With platinum, for example, selling at close to $40,000 per kilogram, a price that is itself escalating, the case for lunar mining is clearer than that for more plentiful products like cobalt.
How will the mining be accomplished? That’s left for someone else to write a paper about… but how we might get there and back again gets a look-in.
Andrews proposes a lunar sling for launching metal products to Earth, but goes into greater detail on what any space infrastructure requires going out of the gate: A simple and inexpensive way to get to Earth orbit, what he calls FRETOS — Fully Reusable Earth-to-Orbit Systems. A fleet of five launchers supporting a flight rate of 1000 launches per year using four tethers is at the heart of the proposal. On the space side, a Skyhook capture device located at 300 kilometers orbital altitude is part of a picture that also includes a Low Earth Orbit station at 1000 kilometers, a powered winch module at 1700 kilometers and a counter-balance at 2400 kilometers. The total mass of the space segment is estimated at 190 metric tons, including 2100 kilometers of tether lines, high-speed winches, power generation arrays, counter balances and station-keeping components, all to be launched separately and docked together for assembly.
All hypothetical at this point, of course, but the space where possible and plausible overlap is a nice place to hang out… that’s why I read science fiction, at any rate. 🙂