The prospect of exploration in space for minerals has been the substance of science fiction, but in the face of a rapid depletion of non-renewable resources, and a likely downturn in funding for space projects in general, in these times of austerity, "mining asteroids" has emerged as an apparently serious proposition. Two companies, "Planetary Resources" and "Deep Space Industries", have now unveiled their plans to look for precious metals, such as gold, platinum, rare earth elements, on asteroids. It is believed that water, which is costly to send up in space, might be present as water-ice, and so might be converted to rocket fuels to support space vehicles, or even breathable oxygen, for the new industry. It is postulated that a space fuel-station might be in operation by 2020, and from where, fuel such as hydrogen could be transferred down to earth orbit to refuel commercial satellites or spacecraft.
Deep Space Industries intends to send out smaller (25 kg mass) vessels - "Fireflies" - fitted with low-cost CubeSat components to explore asteroids for potential bounty, and their launching-costs would be brought down by being launched with heavier, commercial communications satellites. It is anticipated that the first launch will take place in 2015, and that the fireflies will be sent on a journey of 2-6 months, equipped with telescopes that can sense from remote the presence of particular elements. Having targeted a likely source-rock, larger craft - "Dragonflies" - would next be sent out, on round trips of 2-4 years, to physically recover up to 70 kg of material.
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It is thought that only by mining resources in space, can permanent space-development be made economically viable. Initially, Deep Space Industries intends to sell observation platforms in orbit around Earth to prospecting services, as the industry opens-up on a free-market basis, but that actual mining will be underway during the next decade. There are thousands of asteroids that pass fairly close to Earth, which it is considered might be ripe for harvesting. Space-tourism also appears to be another potential income stream.
This is very much a case of playing the longer game, and it might be decades before investors get their money back, if they ever do, e.g. platinum now costs around $1,600 an ounce, and in comparison, a planned mission by NASA to bring back 60 g of material from an asteroid to Earth is expected to cost about $1bn http://www.bbc.co.uk/news/science-environment-17827347. Since this represents the price of 18 tonnes of pure platinum, the Energy Returned on Energy Invested (EROEI) is very far into the red, given the likely quantity of asteroid material to be recovered. Hence, the case for a viable industry on this basis is not compelling. Most likely, whatever materials that are recovered in space, would be best used in space, so that their value is increased by virtue of not having to transport them from earth, e.g. for their use in space stations. That said, the likelihood of establishing a self-sustaining space-based, space-industry must be questionable, in terms of the energy and other resources, including actual metal extraction and device fabrication, that would be required.
As far as mining gas and oil on asteroids is concerned, in terms of EROEI the notion is no more than a pipe-dream, and rather we must confront the falling EROEI for such resources as already pertains on earth, since the emerging "hole" in conventional crude oil and gas production must increasingly be filled by unconventional versions, that are more laborious and thus more expensive to provide.
By. Chris Rhodes