Ok, so we got a potential bootstrap for on-orbit ore refining now. That's cool, that's one of the things I didn't expect, apart from specialised zero-g refining processes for a small amount of highly-pure alloys, which there would be a limited market for. That would probably start somewhere in HEO or potentially lunar orbit, and start moving to the trojan points. Although we're really not sure if earth has any torjans to speak of... so far we're only certain about one, and it's not that big. Still, there's something to be said about the location: It's stable, it's a decent distance away from earth, making it less of a problem to divert and capture asteroids there, and it's got pretty much constant sunlight. So that seems great even if there isn't already a lot of material around to get started with, though that would be quite a bonus.
Now, what other things do we have? Well, propellant is an obvious one. Unless we can meet most of the propellant needs without launching stuff from earth. The things available in space most usable for propellant would probably be oxygen and hydrogen. That is, water... A precious thing that would also be required for tons of other stuff, like producing solvents, radiation shielding, and obviously human consumption and hygiene. So water is a big thing... the more we can get, the merrier.
Apparently it is assumed that NEOs actually carry quite a lot of that stuff, though as I understand it this is inference: There is more water on the moon than expected, and cometarry impacts are too high-energy to deposit the stuff, hence we think it was deposited there by meteorites instead, hence we assume that meteorites carry significant amounts of the stuff. So some of the on-orbit water would be byproducts from our ore refining. Most of it would probably come from the moon, though they'd also need a lot of it for themselves. There's a paper here that I haven't found the time to read yet, might prove interesting: https://www.researchgate.net/public...borative_Study_of_Lunar_Propellant_Production
There might be other sources of propellant... The moon has a good deal of aluminium, for example, which makes for a decent solid propellant. Not really what you'd want for on-orbit operations, but probably not bad for braking the ore payloads to earth into re-entry, or launching stuff from the moon itself. Any other ideas?
I can't really think of other sources of water, apart of course from recycling. There's also another thing that comes into this, which are hydrocarbons, which are required for almost any kind of plastics (also make great propellant, but I don't think there'd ever be enough of them to use them for that).
So Feces might literally be worth their weight in launch costs, but processing them is kind of a specialised procedure. So... what's the chances of actually getting dedicated orbital sewage plants? They wouldn't be like sewage plants on earth, of course. Getting the water out of the crap (pun intended) should be possible via freeze-drying, a relatively simple process that is best performed at the location the feces were "produced", and the frozen dungheaps could be ferried to a facility that can break them down into hydrocarbons, probably even cracking them right away.
Now, what other things do we have? Well, propellant is an obvious one. Unless we can meet most of the propellant needs without launching stuff from earth. The things available in space most usable for propellant would probably be oxygen and hydrogen. That is, water... A precious thing that would also be required for tons of other stuff, like producing solvents, radiation shielding, and obviously human consumption and hygiene. So water is a big thing... the more we can get, the merrier.
Apparently it is assumed that NEOs actually carry quite a lot of that stuff, though as I understand it this is inference: There is more water on the moon than expected, and cometarry impacts are too high-energy to deposit the stuff, hence we think it was deposited there by meteorites instead, hence we assume that meteorites carry significant amounts of the stuff. So some of the on-orbit water would be byproducts from our ore refining. Most of it would probably come from the moon, though they'd also need a lot of it for themselves. There's a paper here that I haven't found the time to read yet, might prove interesting: https://www.researchgate.net/public...borative_Study_of_Lunar_Propellant_Production
There might be other sources of propellant... The moon has a good deal of aluminium, for example, which makes for a decent solid propellant. Not really what you'd want for on-orbit operations, but probably not bad for braking the ore payloads to earth into re-entry, or launching stuff from the moon itself. Any other ideas?
I can't really think of other sources of water, apart of course from recycling. There's also another thing that comes into this, which are hydrocarbons, which are required for almost any kind of plastics (also make great propellant, but I don't think there'd ever be enough of them to use them for that).
So Feces might literally be worth their weight in launch costs, but processing them is kind of a specialised procedure. So... what's the chances of actually getting dedicated orbital sewage plants? They wouldn't be like sewage plants on earth, of course. Getting the water out of the crap (pun intended) should be possible via freeze-drying, a relatively simple process that is best performed at the location the feces were "produced", and the frozen dungheaps could be ferried to a facility that can break them down into hydrocarbons, probably even cracking them right away.