Macgyver ISRU, creative uses of regolith.

[Hyperspace Industries]

In the field of ISRU pretty much all discussion that I’ve seen revolve around water electrolysis (be that for methane or hydrogen and oxygen) and a bit about alumina on the moon.

But, there are many more materials in regolith, which can also be utilized. After some thinking and research, I have come up with some basic ideas:

1. Calcium oxide: Present on both Mars and Luna, with a ten percent concentration on Luna, Calcium oxide can be useful for life support, it will (albeit slowly) absorb carbon dioxide to become Calcium carbonate, better known as Chalk, which can be heated to release carbon dioxide and be used again, acting as an ISRU CO2 scrubber. It can also be reacted with water to produce Calcium hydroxide which absorbs CO2 much faster, but if at all possible I would advise against wasting water on this and using calcium oxide.

2. Perchlorates: Martian perchlorates in regolith tend to have to be removed for safe agriculture, most ISRU systems discard them, but that is not the best of ideas, since they are oxidizers, used often in fireworks, they could be used as solid rocket fuel, or alternatively, be heated to produce an oxygen supply for the base, without having to electrolyze water, which would allow water to be saved, potentially enabling bases to be constructed in less water rich areas.

Do you have any other ideas on utilizing less discussed resources? I’d love to hear them.

Also: is there any other hydrogen containing compound that is at least a tad easier to get in space than water? If there is, we can use oxygen from other sources and hydrogen to make water, which is currently one of the biggest bottlenecks for bases.

[JoeSchmuckatelli]

I don't know the answer - but I like where you are going!  Be interested in the responses from those who have solid chemistry backgrounds! 

[Hyperspace Industries]

Well, turns out Harvard beat me to it, I found a paper which discussed extracting regular hydrogen (just H2) from lunar regolith, according to the apollo mission samples the concentration ranged from 50-220 parts per million (average of about 150 grams per ton of regolith), not much of course, but it's everywhere, and we have industrial capacity and automation to play with. They discussed using bacteria to do it, but they also stated that it could be baked out.

You could have a bunch of rovers which take in regolith on the front, bake the hydrogen out in the middle, and spit rocks out of the back, then when they have gotten, say a 150 grams of hydrogen (which could be done in 20 minutes if they can process 50 kilograms per minute, which ought to be feasible with sufficient heat and/or sufficient numbers), they go back to base to deposit it.

This is probably not just on the surface level though, so you could mine down into everywhere else, and since you already would need other mines, you could extract the hydrogen first.

[Hyperspace Industries]

New ideas:

Iron oxide: Heat it up and react it with carbon monoxide (it needs to be hotter, but it saves you the trouble of getting carbon, though you could still get carbon) to make iron. My preferred in situ spaceship construction material, because I refuse to spend the ridiculous amount of energy needed to get aluminium. (And it is ridiculous, on earth aluminum ore is sent to places like Iceland to be processed purely because of the cheaper electricity there.)

Crew biowaste: Solid biowaste can be heated in a low oxygen environment to produce carbon monoxide (wood gas), water, methane, and carbon residue (ash and soot). The water would be drunk, the carbon and carbon monoxide would be used for iron refinement, the methane could be cooled and used as fuel, or burned for more water, along with CO2 to feed microalgae to be turned via heating to oil (literal oil, fun fact, pretty much every geological compression based reaction can be replicated in seconds with sufficient heat (notable exception, diamonds, since carbon burns)) for fuel, and which can liberate oxygen for oxidizer, or feeding farms for algae (specifically the bacon tasting seaweed Dulse (I think that's how to spell it), or alternatively regular plants which can either be eaten or fed to livestock (I know it's a waste of mass but I love me some pork and chicken wings).

I once again ask, does anyone have any other ideas?

[AngrybobH]

The knowledge required to go from standing naked in a field to wearing synthetic clothes and video chatting with someone on the other side of the planet inside a temperature controlled room is really what is required for ISRU. To say it's vast would be an understatement. This is a subject that fascinates me but I don't have the education required to add to it meaningfully. I do though have some random thoughts.

On 6/13/2022 at 10:26 AM, Hyperspace Industries said:

ridiculous amount of energy needed to get aluminium

If you think about the ways to get power(heat or electricity), it is possible to end up in a situation where you have an excess. Especially when you don't really need to worry so much about environmental damage (can't make the moon MORE dangerous for instance). I'm not dismissing the difficulty of heat and power management but, say on the moon for it being close, enough stuff can be sent to have plenty of power. That makes aluminum...I want to say trivial. But that leads to the thought of radioactive materials. If you have fission reactors on the moon, can you refuel them with locally sourced materials? (a quick search revealed an article from 2009 about the discovery of uranium on the moon, so maybe). If everything comes down to heat or electricity, wouldn't power be the most important? With enough power we can always use the preferred human method of brute force for anything we need.

Also, if you have aluminum (non-oxidized) but you need iron (unsure of how you would end up in that situation) and all you have is iron oxides, thermite is a fun and exciting reaction that lets off some heat.

[mikegarrison]

The problem is not the oxygen. There is lots of oxygen bound into various oxides. The problem is the hydrogen (or really, the lack of hydrogen).

Strange that the most common element in the universe is so hard to come by on a place like the moon, but it is. It's too light, so unless it is bound to something else, the solar wind just blows it away. And without hydrogen, you have lots of problems.

This is why for both Mars and the moon people are obsessed over finding water there, because it's a source of hydrogen that they desperately need.

Edited June 16, 2022 by mikegarrison

[farmerben]

Sodium potassium alloy could be used as a hypergolic liquid fuel.   I have no idea what the ISP is, probably nobody has made a rocket with it before.  

Hydrogen and nitrogen are precious on the moon.  Almost any regolith mining operation is likely to have sodium and potassium byproducts.