Sometimes I devise backgrounds/universes for SF stories. I never write the stories (because I’m no good at devising plots), but it’s fun to do the universe. Anyway, I’m having a bit of difficulty with one aspect of my current one.
Consider a colony on a planet that has no native life. It’s roughly Earth-sized and the temperature is not too uncomfortable. It has an ocean, but since there’s no native life, the the atmosphere is nitrogen-CO[sub]2[/sub] plus the usual trace gases. There is a bit of oxygen due to photodissociation, but it’s just a trace. They’ve introduced cyanobacteria to the oceans, but that’s going to take a very long time to produce significant amounts of oxy in the atmosphere.
Also, since there is no life, there’s no coal or other fossil fuels. And since there was no Great Oxygenation Event, there are no iron ores as we have them on Earth.
So how does this colony produce metals (iron, copper, etc.) that they need?
Does the colony still have space travel? Perhaps they could do asteroid mining. (With some method of very carefully dropping ore shipments–not too large!–in a controlled fashion into the planet’s oceans for retrieval.)
Yes, they do have space travel, but maintaining it consumes the majority of the colony’s GDP. And I’ve considered having asteroid mining, but was wondering if they could avoid it. If they could somehow make metals on the planet, it’s likely to be cheaper.
You should still find some mineral iron deposits like hematite or magnetite around volcanic flows and hot springs. You could have them do some terraforming and create their own bogs with modified peat moss or tailored bacteria to provide the oxygenation necessary to precipitate out iron oxides.
I’m guessing here, though, since I’ve very little geological knowledge.
With Sleel. The metals are present, just not in easy to process concentrations so a method to filter them out into if not necessarily pure at least aggregate form would have to be devised.
Most iron would probably exist as sulfides like pyrite (supposing the planet has sulphur). In the absence of coal or natural gas, the production of iron metal would presumably start by using whatever available power source (hydroelectric, geothermal, nuclear, solar) to split water into H2 / O2, then converting the iron sulfide to oxide by roasting in oxygen, and finally reduction of the oxide with hydrogen in a furnace. You could get sulphuric acid as a useful by-product.
Look for asteroid impact sites. You may be in luck and find a place where a nickle-iron asteroid hit and left a good deposit of metal ore under the crater site. (Like the Sudbury Impact Basin, where much of our platinum group metal comes from, except you’re looking for iron.)
Would think an advanced society would be able to convert whatever raw material is plentiful into various composites requiring little metal content.
Freed of economic constraints by a more efficient process something like gorilla glass could replace much of the metal families manufacturing utility, graphene electrical applications etc.
(a) occasional serious tectonic events that result in iron deposits from the core same as many other mineral veins. (Meteor strikes probably help).
(b) The oxygenation event came from the seawater dissolved iron. Presumably in an oxygen-poor world, you could electroplate your minerals out of the sea, then refine the iron from that?
Your alternative energy sources would be just that - solar, wind, geothermal especially, etc. Maybe you could even refine and burn free methane out of the atmosphere, you would just have to produce and capture oxygen too. Dry out mats of proto-plants and make your own peat moss to burn?
Your knowledge of geology and metallurgy clearly exceeds my own, but what about aluminum? it sounds like they have the same problem with iron that we used to have with aluminum. Maybe a similar approach could be taken with the iron?
Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth’s crust. It makes up about 8% by weight of the Earth’s solid surface. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals.
So unless that alien world is really alien, it’s going to have plenty of Aluminum.
Someone correct my geological ignorance, but prior to the great oxygenation event wouldn’t what are now veins of iron ore, have been more or less veins of elemental iron?
If the planet is similar in composition to the earths crust, sulphur is a much much lower concentration than iron in the crust, there’s just not enough of it to turn more than a very small percentage of the total Elemental iron into Iron sulfides.
No. The iron was previously dissolved in sea water. Oxygen from cyanobacteria combined with the iron and the resulting rust settled out in sediments.
Note that the colony in question is small. It’s a long way from the home planet, and even with a form of FTL (exactly which form is unimportant here), it takes a long time to travel between the two. Long time as in several years, although over time, that gets progressively reduced. So what’s desired is fairly simple technologies. Some stuff has to be imported, of course, but it’s desirable that the colony be as self-sufficient as possible.
Power on the planet is mostly from a hydro dam. It’s used mainly to produce rocket fuel (LOx and LH) for the suface to orbit shuttle[sup]1[/sup] but I suppose some can be used to make aluminum.
I’d really be surprised if we ever get away from using steel. It’s properties are just too good for so many applications.
You’re never freed from economic constraints. They just change. And what’s economic to produce on Earth is not necessarily economic to produce 100 light years away.
Anyway, you guys have given me an idea or two, so thanks to everyone.
[sup]1[/sup] Not the same as the recently retired shuttles, of course. Vaguely similar, but much cheaper to run and much more robust. No solid rocket boosters, for example. Still expensive for a small colony to operate, though.
How about building a bacterium or other microorganism that can filter sea water and concentrate iron or other mineral? This has been proposed for gold on earth, but the concentration is so small.
Since your colony is already into microbiology (seeding the oceans), maybe they should go full-on into microbiology and breed microbes to concentrate whatever metals they need from the planet’s crust/oceans/volcanic deposits/air.
Yeah, this is what I was going to recommend. It might even be plants we already find on Earth, since the environment on this alien planet sounds friendly enough that you could probably find something that could grow there. Let the plants concentrate the iron and then work to extract it from them.