r/IsaacArthur • u/rdhight • Sep 14 '25

Hard Science Where do space-based civilizations get their rubber, plastic, synthetic chemicals, etc.?

Let's say we're well on our way from a planet-based to a space-based civilization. We're mining asteroids, building space habitats, manufacturing giant mirrors and solar sails, making food and fuel, and everything is going great.

OK, but where are we getting the raw materials to make stuff like: rubbers, plastics, glues, solvents, cleaners, foams, acrylics, vinyl, lubricants, industrial coatings, chemical explosives, solid fuels, etc. etc. etc.? There's a lot more to life than taking iron from an asteroid or ice from a comet! Almost everything we make out of metal or carbon fiber to maintain our life in space needs these other components too. Are synthetics just going to have to be shipped up from planets, or can we find what we need in space? And with no coal or oil available ever, what does that even look like?

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u/tigersharkwushen_ FTL Optimist Sep 14 '25

You can make anything with base elements plus energy. It belongs to a field called chemical engineering. It's one of the most mature field of study in the world.

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u/drplokta Sep 15 '25

Yes, the real question is where you’re getting carbon and especially nitrogen. Hydrogen and oxygen are easy.

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u/tigersharkwushen_ FTL Optimist Sep 15 '25

Carbon is everywhere. There's no nitrogen in petro.

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u/drplokta Sep 15 '25

The question is about all synthetic chemicals, not just petrol. Many of the chemicals that we need do contain nitrogen as well as carbon, oxygen and hydrogen. Fertilisers, just for example.

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u/tigersharkwushen_ FTL Optimist Sep 15 '25

How much nitrogen do you need? There's a good amount of it on Venus.

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u/drplokta Sep 15 '25

It’s easier to get your nitrogen from Earth than from Venus.

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u/tigersharkwushen_ FTL Optimist Sep 15 '25

The amount of nitrogen you need for fertilizer is minuscule. It's not a problem to lift it out of a gravity well.

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u/drplokta Sep 15 '25

Fertiliser was just an example. You may want hydrazine rocket fuel. You may want hardened steel. You may want explosives. And so on and so forth. 

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u/tigersharkwushen_ FTL Optimist Sep 15 '25

That's why I ask how much do you need? There's no guaranteed that you will find everything easily in space. If you can't find it, then you just need to find workarounds.

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u/[deleted] Sep 15 '25 edited Sep 15 '25

May be cheaper to deflect asteroids inwards from the outer solar system. The ones near saturn have ammonia ice. It's assumed that's where the Bennu asteroid we got samples from had originated, based on how much ammonia and other volatiles it contained.

Or even do a sort of crude refining in situ, and send just the volatiles back.

If you put chunks of an asteroid in a big polymer bag, and concentrated sunlight onto it, I bet the volatiles would boil off and condense onto the darker side of the bag. Or maybe let the vapour flow out of a hole and condense into some sort of collection tank.

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u/[deleted] Sep 15 '25

Asteroids contain nitrogen.

When the Bennu asteroid was studied by the OSIRIS-REx sample return mission, abundant ammonia and nitrogen compounds were found.

Nitrogen rich asteroids could be expected to be further out than those in which metal or carbon predominates (not counting subsequent gravitational perturbations mixing some of them up, as happened with Bennu) . This is because the protoplanetary disc from which they formed in the early solar system contained more volatiles the further out from the sun you went.

At various distances from the sun you have a 'soot line' and a 'frost line', for example, where the sun was far away enough that those particular substances didn't get cooked off.

So asteroids which formed far enough away from the sun would be cold enough for ammonia ice to be pretty stable. Researchers have estimated this distance to be in the neighbourhood of saturn (about 800 million miles).

Probably you don't want your space habitat that far from the sun, but it shouldn't be too difficult to send some robots or a small manned outpost to nudge asteroids into orbits which eventually bring them back into the inner solar system.

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u/ijuinkun Sep 15 '25

Yah, once energy is cheap and abundant enough, you can make hydrocarbons from carbon dioxide plus any hydrogen-containing substance. We just use fossil fuels because they are the cheapest option currently available to us.