[SCM-Enthusiast]

>fuel

Hydrogen and oxygen can be made from water, and methane can be made from regolith and water.

>where would this "cislunar orbit economy" find a market?

The uniform distribution of microgravity lends itself to advanced manufacturing methods that cost hundreds if not billions of dollars to replicate here on earth. soooo many of earths manufacturing methods use very expensive means of creating the vacuum that is required, that is provided free in space.

Semiconductors. Turns out here on earth the machines costs hundreds of millions of dollars to etch a wafer because of the use of various technologies to create vacums, control for foreign material, and ensure the micro etches "Stay" and the material "goes". There is a wide discussion, and multiple tests conducted on the ISS that has confirmed this. So, space may be the only way to build next-gen semi conductor tech to get us below 2nm, and a much higher yield, with much cheaper equipment. With the cost of a launch at ~100m on a falcon, the launch would be cheaper than the equipment they are sending up.

ZBLAN fiber optics, growing protein crystals, Electron Beam Physical Vapor Deposition, Regolith refining,

are all done better in space. And they will be cheaper in space, and on the moon and mars. They will be more expensive on earth due to the large gravity well.

[usrbinbash]

> Hydrogen and oxygen can be made from water

Judging by [this][1], good luck trying to find adequate supplies of water on the Moon.

> methane can be made from regolith and water.

Again, good luck with that, because as shown [here][2], the amount of carbon in the lunar soil is, shall we say, not great. And since we are already talking about an immensely energy intensive process here, breaking down rocks in a smelter to get at tiny amounts of Carbon, may not be a very good solution.

So to have a chance at an adequate supply of CO_2 for the Sabbatier Process, you'd have to mine cold-trapped carbon dioxide. Which [may exist][3], or it might not. If it exists, it exists in the coldest regions of the moon, aka. places where you have no access to the only available energy source (Solar). Good luck hauling dry ice across the Moon to the base, especially since it will cease to be a solid the closer the transport comes to the processing plant.

And this process btw. requires HUGE amounts of energy, equipment, machinery and storage infrastructure. [This video][4] gives you a good idea of how difficult making CH_4/LOX fuel with ISRU using the Sabbatier process is ... on Mars, where you can actually pull CO_2 from the thin atmosphere, and likely have more water available.

So in summary:

1. No, we cannot just make the fuel on the Moon

2. Even if we could, it would likely end up being comparatively easier to just ship it there from Earth

3. Even ignoring all that, good luck making the amounts required to keep industrial-scale launches of materials happen

> control for foreign material

If you want to have a real challenge regarding keeping foreign material out, then try manufacturing things in an environment that is filled with hyperstatic, completely dry, microabrasive, pulverized regolith, and having to build clean rooms in an environment with the kind of temperature differentials experienced between the lunar day/night cycle, or worse, in space.

Also, if a clean room fails here on Earth, it's a huge headache for everyone to recover it. If an airlock fails on the Moon, people die, and the production facility gets destroyed by explosive decompression.

> And they will be cheaper in space, and on the moon and mars.

No, they won't, because again: These materials, even if they actually benefited from being produced off-world (and that's a big IF) will only be of any use here on Earth. There won't be any self-sustaining colonies in outer space, or on the Moon, or on Mars. There won't be sprawling industrial sites. We'll be lucky if we can keep a small crew of Astronauts alive on another Planet or the Moon for a few Months until they can get back and start the recovery process after having their bodies wrecked by Microgravity for a prolonged period of time.

So the only market for ANYTHING produced "up there", is "down here", and this, again, is where the prohibitive transportation costs come in and make the whole discussion moot.

[1]: https://en.wikipedia.org/wiki/Lunar_water

[2]: https://en.wikipedia.org/wiki/Lunar_soil#/media/File:Composi...

[3]: https://www.sciencedaily.com/releases/2021/11/211115151010.h...

[4]: https://www.youtube.com/watch?v=Wum8_8sWdeU

[SCM-Enthusiast]

I get the direction that the video was going on... but all it did in my mind was prove that it was completely possible. 5k solarpanels, two full football fields or 17 small nuclear reactors is all that is required for the process? I would have thought it'd be more.

I get what you're saying... it will be hard... for sure... Is it possible in the timeframes being discussed? probably not. Is it an endevor for our generation to embark on? yes. It's the greatest adventure ever written, and yeah... it's gunna suck for all people involved. It's a hostile wasteland.

With that out of the way... I think the video you linked tells the story dishonestly. The deltav required to get from mars, nor to the moon back to the ISS, is no where near refilling a full tank. Without a retro burn, it would require around 1/8th of the deltaV.

Secondly, you can send 10, 20 starships before, or each cycle and spin up. No one is saying that the very first time you send people they will use Insitu 100%. Maybe they bring the hydrogen, or the carbon dioxide and try and get a plant going. Or they can send all the fuel required beforehand. Once they have some kind of more permanant presence, they can slowly ramp up and take a more and more of the process on.

Not all these projects need to be solved at once. With 100T carrying capacity of each starship, all the youtube video convinced me of that it will take around 30-40 starships... which isn't that wild.

I would be more interested in what you think about the more advanced manufacturing, despite all the problems and infrastructure required?

[usrbinbash]

> is all that is required for the process?

No, that is only the panels required just to generate the electricity for the process.

This does not include, among other things: cabling, scaffolds, mountings, inverters, electronics, any batteries to cover operation during the night, any machinery required for mining, transportation, and building, nor building materials, piping, storage tanks, the actual sabbatier reactor chambers, insultation, duct tape, spare parts, tools, engineers, food, water, oxygen, space suits, vehicles, or toilet paper.

And keep in mind that for the sake of simplicity, [this assumes almost total conversion of energy][1] already, aka. almost losslessly converting the electricity harvested to chemical energy in the fuel, which of course doesn't happen in chemistry. It also ignores a whole lot of other stuff, outlined shortly after the timestamp linked.

And all that is to refill a single ship over the course of 500 days. Not a fleet. Not regular starts to support industry-scale transport logistics. One. Single. Ship. Over the course of 500 days

And we are, again, just talking about fuel production here. An industry also needs spare parts, personnel, tools, replacement machinery, building materials. The people working there need food, water, oxygen, toilet paper, ...

You know what else an industry needs? Waste disposal. We cannot just dump metal shavings, etc. into space: Because we are talking about orbiting platforms or something similar here, so these waste products would then become hyper-velocity projectiles ripping everything to shreds. So there needs to be a plan for that as well, which again involves all the same problems.

Another thing it needs: Energy. The video outlines how difficult it is to support even a single, scope-limited industrial process in a place where we cannot just connect to the electric grid or access large natural gas reservoirs. Solar panels are nice, but processes like smelting materials, welding, metalworking, anything that requires high temperatures? Good luck trying to cover that with solar.

And again another thing: Heat dispersal. Ever wondered why the ISS has so many fins? Many of those are not solar panels, they are heat-exchangers. And they just have to account for the body heat of a small group of people and their equipment. Try to imagine what an industrial facility would need, just in terms of that.

Yeah, so all in all, I guess that we won't support a "cis-lunar-orbit" industry any time soon. While in theory possible (as in, nothing so far violates any laws of physics), it simply isn't practical, and the cost of anything, from setting it up to maintaining it, would be prohibitive.

> I would be more interested in what you think about the more advanced manufacturing, despite all the problems and infrastructure required?

First I'd need to see tangible demonstrations that "having zero gravity" confers an advantage in the first place.

What do I mean by that? Simple: Does zero gravity enable certain processes, that cannot be replicated on Earth, and is the cost of setting up such facilities, vs. developing alternatives that work here, where we have materials, labour, air, etc. available really worth it.

Because "greatest adventure" sounds wonderful and all that, but when the term "industry" enters the discussion, we have to talk about efficiency, expedience and ROI.

[1]: https://youtu.be/s-MQrp2P2GI?si=DCLRSeeZ2hLePVAl&t=886