How to make metals from Martian dirt | Hacker News Reader

How to make metals from Martian dirt

csiro.au

80 pointsPaulHoule99 comments

There is the small detail of heating the regolith to 1400c. It's not very clear where that energy comes from (at least not at scale).

Burning fuels seems to be out. So I guess nuclear or solar?

Mars solar is weaker than earth, but I guess let's of panels plus lots of batteries could work. Sorta. Not sure it produces "tons" of material very quickly.

Nuclear is the other option. But would rely on fuel from earth. Not to mention that building a reactor big enough to sustain a colony, plus industry, would be challenging. And of course landing fresh uranium on Mars would be risky. (It's heavy, and any accident would render a chunk of Mars radioactive for quite some time.)

Oh, and the reactor would need to be air-cooled not water-cooled.

But, I guess, yay regolith?

Can't you eventually mine and enrich uranium on Mars itself?

It's possible, although unlikely, that there are mineable deposits of uranium on Mars. There are trace amounts, but its unlikely that minable deposits formed.

why is there unlikely to be mine-able uranium deposits? It's not like there's some geological process on mars that strips it away (presumably).

I think the implication is that uranium likely exists in low density and cannot be easily extracted without a great deal of chemical processing and disposal of waste product (rather than deposits of uranium a la natural reactors: https://en.m.wikipedia.org/wiki/Natural_nuclear_fission_reac...)

I'm not an expert, but I was under the impression that while water is often involved in forming deposits of uranium ores, they can also form because of volcanic activity alone. Maybe bruce511 thinks such deposits are likely to be rare, or maybe I'm wrong.

The geological processes, which Mars lacks, are supposed to concentrate uranium, not strip it away. The actual geochemical explanation is complicated but long story short Mars is a geologically dead planet without much water that doesn’t like to form rock that can hold uranium ore.

Uranium concentrates in felsic (high silica) rock which forms under crustal recycling on Earth - the heat at the interface between the crust and mantle allows the Fe-Mg to strip away. Water dissolving uranium then injects into the felsic rock, the uranium precipitates out, and the rock later gets pushed up higher into the crust.

Mars has neither the active geology nor seemingly enough water to allow much felsic rock to form. Satellite surveys show the surface is covered with mostly basaltic rock (low silica, high Fe-Mg) with very small pockets of felsic. The processes that form these pockets are largely unlike those formed on Earth and don’t have the same geochemistry, especially without ample water.

It's amazing how many natural processes we have on Earth that work in our favour.

I just replaced my screen background with a photo from Mars with a big granitic(?)/ granodiorite(?) Boulder, surrounded by volcanic rocks. It is an amazing quandary! Fun to look at, and think - ok, how was this made!? To simplify: the Boulder: is a white rock with black crystals, whereas all the surrounding rocks are dark grey or black(look like lava.) The Boulder is somewhat round(let's say 1 meter across +-100%), has been broken at some of the edges, and rounded at others. How was it broken? Rounded, and the fact it isn't in the Chevy place judging by the surrounding rocks, HOW, did it get there? So we are looking at various igneous processes at work here. Deep and surface. Plus, transport, by water? Ice? Liquid CO2? Unknown.

https://www.goodnewsnetwork.org/wp-content/uploads/2024/06/P...

Nuclear and solar are actually pretty competitive here at MW scale, optimistic projections for both are in the ballpark of 100 tons per MW including associated power electronics. That's to say, if Starship continues on the trajectory it's on, putting aside a few MW on Mars to operate a smelter is within the realm of possibility.

On a larger scale (GW) the answer is likely nuclear, unless we can come up with a realistic way to produce solar panels on Mars. Mass-wise, nuclear scales very well, but solar is nearly linear.

There's also some possibility we come up with a creative way to produce methane or another fuel.

Solar is likely what will power anything we put there, in the short term at least. But Mars only gets 43% of the solar energy that earth gets. So you need at least twice the panels. Not to mention the batteries.

This is fine for "residential", but perhaps not suited to industrial scale.

Yes, I expect nuclear is the best choice of a list of 1, but it will be substantially harder to build one on Mars than here. For starters the lack of water, and the lack of atmosphere density would result in substantial cooling challenges.

However you slice it, energy on Mars is completely dependent on earth. Panels, batteries, uranium- none of it can be made on Mars, and all have "short" lifespans.

> the lack of atmosphere density would result in substantial cooling challenges.

heat exchange(s) such that the human settlement(s) are warmed by this "waste" heat? Mars is cold, and likely need to have many pipes to generate heat for human settlement, so why not build it in via this need?

Sure, Mars is really cold, so it's natural that this waste heat would be used constructively. There are communities in the Artic circle that do this.

But that's not really the challenge I was referring to. The problem is less "where should the heat go" and more the medium of transport. A closed cycle, pressurized water cooling would likely be used. That has it's own problems, but there's no local water source, and steam , while a possibility, has even more challenges.

Indeed current nuclear uses a steam-turbine cycle for actual generation, and that likely wouldn't work on Mars either. So the nuclear reactor there would be novel in lots of ways.

Ultimately though it will generate more waste heat than a colony can use, and getting rid of the rest in a thin Martian atmosphere (that's also dusty) will be difficult.

Why wouldn’t the steam turbine cycle or pressurized water in the primary circuit work?

Terrestrial nuclear reactors need a lot of water on the tertiary circuit but on Mars that can just dump into the ground instead which isn’t possible on Earth. The primary and secondary circuits are closed loop and don’t need so much water that it would be prohibitive, at least not compared to the difficulty of getting everything else to the planet and assembled.

I don't think dumping heat into the ground would work for any meaningful amount of time - both on Earth and on Mars the dirt and rock are not a very good conductor of heat, so you would quickly heat up your local "heat island" in the ground soon loose the temperature difference to run our heat engine on. Might work for pulsed operation where you wait for the affected area to cool down, but I am skeptical, given that a similar system is used for heat storage on Earth and it can take months to years for the temperature to return to natural values.

Most likely you would have to use air cooling, with lots of fans to push the thin atmosphere through massive heat exchangers. The overall lower atmosphere and general ground temperature (due to Mars being less heated by the Sun) should help offset this somewhat compared to cooling a reactor of the same power output in the vacuum of space.

There already exist better solutions for the primary circuit than using steam, e.g. using supercritical carbon dioxide in a closed cycle. This allows the operation of the reactor at higher temperatures, while also increasing the efficiency of the heat transfer in the heat exchangers, which increases the overall energy efficiency. Moreover, this also greatly reduces the size of all components (which however must operate at much higher pressures than with steam, because that is the reason for the great reduction in size).

Making very big heatsinks to radiate all the heat from a nuclear reactor will not be a problem on Mars or Moon, as long as the metal, e.g. aluminum, is extracted locally. One will have no neighbors and no need to buy real estate, so any amount of land area can be used without restrictions.

Using turbines with a closed-cycle supercritical fluid, e.g. carbon dioxide, is already investigated for being used in nuclear reactors or other kinds of thermal energy plants, here on Earth, because they have various advantages over steam turbines, e.g. a much smaller size, ability to use heat at much higher temperatures and much less consumption of water.

If nuclear reactors will be used on Mars or on Moon, it is pretty much certain that they will not use steam turbines, but closed-cycle supercritical CO2 turbines for the first stage, perhaps with the residual heat used in some closed-cycle turbines using a Rankine cycle with some organic fluid. Water or steam, also in closed-cycle, is likely to be used only for transporting the residual heat of the last turbine stage, which will be used for direct heating, not for electric power generation.

I find it pretty amazing that it only gets 43% of the solar energy as Earth,with it being our neighbour.

Nearest neighbor doesn't necessarily mean a near neighbor. :p (Technically Venus is closer, but in the other direction.)

Compared to Earth, Mars is ~1.52x as far from the Sun, which is a pretty hefty jump!

As you travel the distance from the sun by a factor of R, the same sunlight energy is distributed across a broader "shell" that grows in area by R^2.

1.00^2 / 1.52^2 =~ 43.3%

I can't say it very well so I'll leave it to a great:

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. - Douglas Adams

Until we can manufacture solar panels on Mars, maybe the best option is solar power satellites with microwave transmission.

One of the big drawbacks on Earth is that you have to launch the satellite to orbit. For Mars, stuff is in orbit when it gets there, and landing it is the challenge.

Mars has an axial tilt similar to Earth's, which means that, like Earth, a satellite in stationary orbit will have full "noon" sun 99.5% of the time. A solar panel in stationary orbit around Earth will collect five times as much energy in 24 hours as one on the ground. The Martian atmosphere would filter less sunlight, so call it 4X for Mars.

Batteries are getting cheaper on Earth but they're still a lot of mass to send to Mars. Near-constant uptime with satellites mostly eliminates that problem.

At first, you do have to land the ground collector, but it's mostly antenna wire. Should be pretty robust and you won't have to worry about keeping the dust off it. Once you're making metals from Martian dirt, you can produce most of it locally, from dirt.

The biggest downside compared to nuclear would be that dust storms would at least partially block transmission.

Could always build a helioplex - a gigantic solar concentrator.

cooling can be done with radiators pointed north, into the permanently black sky,with essentialy no convective heat gain or loss, build for noon in mid summer, and forget about it lots of things work on mars that dont work here, Thin film prevoskerite solar ,which is sensitive to water and oxygen and therefor difficult here, can be sprayed on whatever is handy on mars(oversimplification, but), and the same goes for a smelter that is electric, where one of the byproducts is oxygen driven off, hand that, and that high quality metal and castings will be possible as the lack of atmospheric oxygen and low pressure will de gass metals, also metals wont corode after bieng made. given the very low night time temperatures, it should be quite easy to liquify martian "air" and use it for day time cooling where needed and also the exraction of trace gasses other than CO², which is the bulk.

none of that maters without a good supply of water to crack for fuel and air and general living, and as there is a whole world to work with, it is likely that there are a few areas that will have a fortuitous convergence of ALL the things possible, in one spot, kind of like early settlers finding a stand of trees, felled by beavers, bark stripped and pre notched for assembly into a cabin, next to a pond with fish and medows all around

to put things in perspective

pure gold would be good for use as sheet metal, as it's ductility and ease of refinement would make it the cheapest alternative

it's doable, but only just, and only if we get our shit together and decide that an impossible, ultra long term project to become an interplanitary species is a better way to use our excess capacity than whatever the fuck it is we are doing now

Cooling a large nuclear power reactor would be a challenge on Mars. Probably you'd want something compact that runs at high temperature, like a molten salt design, to make heat rejection easier.

Edit: side benefit would be you could use the heat directly for processes like this metallurgy thing.

Cooling is should not be an issue, considering it goes to ~-80C at night, we only need a smart way of harnessing that difference.

Mars atmosphere is so thin that it won't really help to cool down a reactor.

No, it absolutely will be an issue. You need to dispose of ~100 MW of heat energy. Simply dumping it into ground will quickly heat it up, you can't rely on water evaporation for obvious reasons, same goes for convection because of the thin atmosphere. So your only option is radiative cooling, either by using ground or dedicated radiators. But because it's relatively inefficient, you will need a lot of area and materials for it.

High-temperature reactor designs are essential. Radiative heat transfer scales with temperature to the fourth power.

So if you reject 100 MW of waste heat at, say, 400°C (750°F), a radiative heat transfer area of 10,000 m^2 (i.e. 100m x 100m square) would be sufficient. That's quite big and hot, but 100 MW is a lot!

Radiative heat rejection at 100°C would require 10x as much area.

Disposing heat at a higher temperature would also mean that you need to dispose of more heat (~2x in the case of 400°C vs sub-100°C) and losing energy which could've been used for useful work such as generating electricity.

It may be reasonable to do at early stages, but after the colony is able to produce metals in situ it would be better to build more radiators. Especially considering that you also need to dispose latent heat from other sources.

...which is why you would want to fabricate as many of those radiators as possible on site, with local materials. And also why one of the key requirements for space base nuclear reactors is "scalable".

>It's heavy, and any accident would render a chunk of Mars radioactive for quite some time.

Do you think that nuclear fuel is some kind of green glowing stuff like in Simpsons? New nuclear pellets is just a bunch of uranium dioxide, which is mildly alpha radioactive. In other words, as long as you are not inhaling its dust, it's more or less safe to handle even with bare hands.

Even the worst possible kind of accident is likely to be absolutely irrelevant from the radiation safety point of view considering high levels of natural solar radiation on the surface of Mars.

Heating stuff to 1,400C is also a solved problem, but he seems to be unaware of that as well.

The guy's clearly not the sharpest tool for this ...

Small reactors have been done by NASA, among many other organizations, for decades.

Also uranium is not as radioactive or lethal as you'd think in this case. It can be sent there safely and without issue.

Also reactors can be MSR (molten salt reactor) greatly reducing water needs.

"It's heavy, and any accident would render a chunk of Mars radioactive for quite some time."

If you model the rest of the universe out of Earth's highly protective environment as "already being the result of a major nuclear accident", you're not actually that far off. The people evacuated from Chernobyl received about 33 milli-Sieverts of radiation [1]. The surface of the moon gets about 60 micro-Sieverts of radiation per hour[2]... or, in other words, being on the surface of the moon for 20 days is the rough equivalent of experiencing one Chernobyl disaster. This is just a rough estimate for intuition purposes, it's not exactly the same radiation in both cases, but it's close enough to make the point. This page [3] says the surface of Mars is about .7 milli-Sieverts of radiation per day, for about 30 micro-Sieverts per hour (to use the same units as the moon above), which is about right for the inverse-square and slows the exposure to one Chernobyl per 40 days.

And by universal standards, that's still rather low radiation. There's entire galactic clusters with the central blackholes blasting sterilizing amounts of radiation out into their entire cluster. Earth is fairly special; a good reason not to mess it up. The "jump to Mars plan" is perhaps not impossible but it's really, really, really hard.

[1]: https://nuclear-energy.net/nuclear-accidents/chernobyl/chern...

[2]: https://www.space.com/moon-radiation-dose-for-astronauts-mea...

[3]: https://spacemath.gsfc.nasa.gov/planets/10Page74.pdf

I've read some parts of Mars are full of Thorium, sometimes, somewhere.

Calls for in-situ-utilization, doesn't it?

You can get regolith simulant from Amazon, please do try this at home

https://www.themartiangarden.com/ https://www.amazon.com/Regolith-Simulant-Authentic-Martian-R...

Pretty neat. This would certainly make for an interesting Mars mission should SpaceX want to try it, land a lander, have the lander process regolith into iron chunks, create a pile of chunks. All good threshold goals.

What ever happened the asteroid mining folks? They have a similar problem, albeit with very little gravity and no atmosphere, but their metals are in theory worth a lot more (platinum, gold, silver, Etc.)

There was a similar idea/proposal for extracting aluminum from Lunar regolith, also a good space mission for private interests.

Once you've got basic metals you can make more interesting things, with iron you can make reinforced concrete which would be an interesting building material on Mars I suspect.

> There was a similar idea/proposal for extracting aluminum from Lunar regolith, also a good space mission for private interests.

With the asteroids, I assume the idea is to bring enough platinum and gold back to Earth to offset the costs of getting them from space. That doesn't sound especially realistic, but in the right circumstances I guess it could be.

With aluminum on the moon or iron on Mars, that will never happen. You'd have to want to use those materials on location.

So what would the value be of producing aluminum on the moon?

> So what would the value be of producing aluminum on the moon?

Building more rockets? Interesting detail: there isn't enough oxygen there to cause aluminum to immediately be covered with a skin of aluminum oxide. I wonder what the energy cost of an extraction process for aluminum on the moon would be. At the same time I would hate to see the moon mined, that's one piece of common property that we should maybe try to preserve unless we have no other alternative, not just for commerce.

The idea you see in O'Neill and other science fiction that iron is rare on the moon is bunk. There is Hematite

https://www.jpl.nasa.gov/news/the-moon-is-rusting-and-resear...

and Apollo astronauts brought back perfectly good Iron ore. It's true that there is lot of aluminum and titanium on the moon and a lunar economy might use that but there is enough iron that if loonies wanted to make things out of iron they could make things out of iron.

Yes, absolutely, but they specifically asked about aluminum. Mining iron or aluminum on the moon would be trivial compared to earth in terms of access. Getting the gear there to bootstrap it all would be an interesting technical problem but I think it is solvable. Why you would want to do it to me is only to jump start a deep space program taking advantage of the reduced requirements to reach escape velocity while still having a long term platform to build on. If you want to do better than that then space construction will have to go to a completely different level first.

ISRU tends to make no sense at all when you have to move things from place to place, it makes more sense when you use them in place.

For instance there may be some usable ice at the moon's poles maybe even some carbon. You could get oxygen out of rocks one way or another. You could make rocket fuel and launch stuff the conventional way but there are two problems: (1) Earth is the most competitive and cheapest market for everything in the solar system, and (2) lunar colonists might see volatiles as precious and decide to circularize them rather than expend them. [1] [2] Contrast that to Earth which has plenty of volatiles.

There is the idea of O'Neill and Heinlein [1] of the lunar mass driver, the picture you get from The High Frontier and The Moon is a Harsh Mistress that it looks like a maglev train a few km long is totally wrong because your elevation angle is pretty high if you want to target the Earth-Moon L1 point or the Earth or LEO (assuming you can aerobrake reliably) If it is a few km long it is a slanted hole a few km deep. I don't know about coilguns but a railgun with 2.5 km/s that would fit on a ship has been tested [3] and you need 3.5 km/s to get to L1 -- one way or another I think a viable mass driver looks like the Paris Gun and shoots small payloads. If you could launch a 1kg payload per second you could put up a rail car worth of material in a day.

O'Neill's students thought a lot about the "catcher" for stuff from the lunar mass driver and never came up with anything convincing if anybody else has I haven't seen it.

[1] See The Moon is a Harsh Mistress

[2] Niven's Protector talks about the problem of very long-term space colonies , starships and stuff losing volatiles at steady rate no matter how well you try to keep them in.

[3] ... and burns up the barrels

Fascinating stuff, thank you for the comment. I always wonder to what degree the various 'hard SF' authors really run the numbers, some are very good at it, good enough that there are no immediately obvious mistakes, others get stuff glaringly wrong but still spin a good yarn.

> ... your elevation angle is pretty high if you want to target the Earth-Moon L1 point or the Earth or LEO...

You don't point at where you want to go. You point retrograde (relative to the moon's orbit) so that, after escaping the moon, the payload is just past the apogee of a transfer orbit with the desired perigee.

Further, the moon isn't a flat disk, with the Earth "up"; getting the required angle is just a matter of choosing the right place on the surface of the moon (a sphere has multiple tangents pointing in any direction you want).

So no, you wouldn't need "a slanted hole a few km deep".

You may be right but I'd want to see the trajectories numerically integrated and plotted. What I know is that trajectories that hit the L1 point with low velocity will confound your intuition that comes from conics. Here is a recent analysis that considers a range of trajectories launched from a certain point

https://www.sjsu.edu/ae/docs/project-thesis/Ethan.Miller-Su2...

which a student project that has a lot of problems and doesn't consider the possibility of relocating the driver but they are considering moderately high angles of around 30 degrees. Their mass driver is about 500m long in the range that if you want to drill a hole that deep you can drill a hole that deep.

Practically there are other concerns about a moon base, particularly these days people are interested in polar locations. You could possibly run 1000 km of maglev to get to the base of the thing but if you are talking that big you might consider a lunar beanstalk which at least doesn't require a catcher at L1.

A lunar beanstalk? How is that supposed to work? (Answer: it won't; Lunar-stationary orbits do not exist, since they would have a radius on the order of the Earth-moon distance, and the Earth is much more massive than the moon).

https://explainingscience.org/2025/08/19/lunar-stationary-or...

Iron may not be rare but the value of iron ores is subtly dependent on eg, non-iron content

"A few smelting companies formed in the late 19th and early 20th centuries, but were unable to process the ore with any economic success due to the sandy nature and high titanium content, which tended to form hard, brittle carbides in the steel." https://en.wikipedia.org/wiki/Ironsand#:~:text=%5D%20A%20few...

Even today's "economic" process wastes all that titanium (which should be even more valuable for a lunar economy - Ti burning is a major thorn on earth!)

Why preserve the current landscape of the moon? It harbors no life, and its surface is scarred by billions years of space collisions.

Because it is a historical record that we are able to read better and better and I think that the moon's usefulness as a historical record is unique and as a resource for basic building materials it is far less so.

With this framing, is there ever a situation in which it would be okay to utilize the moon's material? It's not like the moon has feelings, and exploiting a bunch of lifeless rock seems better than doing it on Earth, no?

IMO we've ruined the sky already. We can't see all the stars we used to, and new ones (starlink) are visible to the unaided eye. Changing the face of the moon such that it, too, is no longer the same symbol every human has ever seen, feels like a monumental step we maybe shouldn't take. I don't want to see the twinkle of a refinery, any more than I'd want to see a giant McDonald's logo carved into it.

delta-V happened to asteroid folks.

there are no realistic proposals for asteroid drives ala https://en.wikipedia.org/wiki/K240

The product I have in mind is solar sails to be delivered to the Earth-Sun L1 point to counteract climate change. A carbonaceous chondrite asteroid is rich in volatiles to make plastic films as well as metals and stones to coat them with. The pros are:

- solar sails transport themselves without using reaction mass

- you're not competing with cheap resources on Earth to be used on Earth, rather resources from Earth transported past LEO

eliminating many of the fundamental objections to scenarios where ISRU materials get transported somewhere.

Cons are:

- a good sunshade and a good solar sail are different things

- plastic + metal solar sails seem to get corroded badly over time

- if you think the turnaround time between Earth and Mars is bad, you are talking half a decade or more to round trip parts plus a 45 minute communication delay at some times; you either need to send people with all the problems that entails or have advanced autonomy and a manned simulation platform somewhere in near-Earth or cislunar space.

I've got a good picture of what parts of the "head end" that consumes asteroid materials and turns them into reasonable chemical feedstocks looks like with the exception of how to devolatize the asteroid to begin with and where to get the storage tanks to store early offgassing before the metals line comes online. (Storage tanks are an interesting question for manufacturing since the chemical factory needs plenty of them.) I also have some idea of what the "shipyard" that builds the actual sails look like. Trouble is you probably need a Drexler machine to make spare parts and also make customized parts given that you don't really know what you're up against when it comes to the "head end" (though upper pyramid parts of the chemical factory and the shipyard can be simulated close to Earth) ... and Drexler's concept for a Drexler machine doesn't work.

If you so very want some mylar over carbon fiber put up in L1, and not ever launch that from Earth then Luna is the most obviously cheap and abundant source of whatever. No need for asteroids at all. Also the comms delay is 1.25s IIRC.

I personally consider this a folly.

On the other hand, no comprehensive survey of Luna was ever done, and we target Mars or even asteroids why? I'd like some at least plausible reason for this.

It is true that Luna is halfway to Mars in dV on hohmanns. But not in time spent. Never will be.

Luna has the aluminum but probably not the stuff to make mylar or kapton or something similar. You need CHN (Carbon, Hydrogen, Nitrogen) for that.

On the other hand, O'Neill's students did think a bit about how to make metal films without any plastic backing and that might be (1) practical w/ Lunar materials assuming you can get the mass driver, catcher and all of that working, and (2) produce a very high performance sail if it survives the corrosive space environment, metal-Kapton sails didn't do that well here

https://en.wikipedia.org/wiki/IKAROS

> to counteract climate change

Seems way easier to get our act together on earth. It's all solved from a technological angle.

the economic angle far outweigh the technological angle.

And the political/religious angle, don't forget that one. Hate against "woke" goes deep, gotta drive that diesel F150 cause that's our patriotic identity!!1 /s

The economic angle argument backfires though in this thread's context. If fixing a little bit of behavior down here is too expensive then it surely is prohibitively expensive to attempt all that on a different planet. Everybody not seeing this as obvious has watched too much scifi.

Uhh... Why? Getting stuff from an asteroid orbit to Earth needs a delta-v of around 1 km/s. You can even get to circularize the orbit if you're comfortable with doing a couple of gravitational assists.

You won't be moving the whole asteroids, but a few hundred tons of extracted platinum-group metals? Certainly doable.

Apropos of nothing, was the PC version/successor Fragile Allegiance as good/better than K240?

It's mostly same gameplay-wise. Fancier graphics, clunkier interface. K240 under Amiga emulator ran way better than original FA under dosbox until GOG or someone released pre-dosbox-ed version. This runs fine if you want to try.

Why can't you just use a mass driver? Just mine bits of the asteroid and fling them. The biggest problem would be fueling this, and nuclear is probably quite cost effective. (Shout out to KSR's fantastic mars trilogy for this idea.)

Sure, this would be slow. But I think it'd be viable. You could move them into earth's orbit or even slam it into the moon.

A mass driver would run off a capacitor bank most likely - can't you just charge that by a solar array ? Unless you really need to send huge amounts, this should be much less hassle than lugging a nuclear reactor around. And for near-Earth asteroids, you should get the same power per square meter, but better (no atmosphere & clouds to get in the way) at least half of the time (considering the asteroid rotates - and even that could be handled by clever engineering/tethered array).

Asteroids are hit-and-miss composition wise (though you can determine quite a bit by observing them), but when they are a hit they tend to be really valuable. The problem then is that you need to get to them and then the next problem is that you need to get back to where you came from.

Both of these can hurt your ROI considerably assuming you can solve for them at all with the masses involved. They're also usually moving at a pretty good clip and are bad to set up long term for. I think until we have a long term presence in the asteroid belt that this is mostly going to be SF rather than that it will actually happen.

24/7 solar furnaces harvesting asteroids seems like a huge industry once it's figured out. The big problem is that it would take a billionaire to make it happen.

In short: they just heated some (simulated) Martian dirt, and this alone was sufficient to produce liquid iron, and then liquid iron-silicon alloy. No huge quantities of carbon were required. This is quite surprising to me.

Making steel, with controlled carbon content, would be quite another challenge. Carbon is readily available on Mars, but only in the form of CO2.

Iron would be fine since there’s basically no atmosphere to oxidize it right?

Isn't steel also much stronger?

Iron is a lot heavier than steel and probably weaker too (IINAMS, ask your material scientist)

By "iron", I assume that you mean "cast iron", as pure iron is hardly used for anything.

Cast iron is lighter than steel, not heavier, because of its higher carbon content.

However, objects made of cast iron are indeed heavier than similar objects made of steel, and this is what you must have in mind, because the objects made of cast iron are always made thicker, both because cast iron is weaker, which requires greater thickness for the same strength, and because it is harder to make thinner objects by casting than by forging.

TIL, thanks!

No, steels have 4-6x higher tensile strength (and better performance in other related properties) than raw iron. [0] They're not just preferred over iron for their corrosion resistance.

And note that even what we call "cast iron" - a material that reasonably could be preferred to steel for some industrial purposes - is an iron-carbon alloy that in fact has more carbon than steel[1].

[0] https://www.texasironandmetal.com/strength-of-steel-compares...

[1] https://en.m.wikipedia.org/wiki/Cast_iron

oxidation is a chemical process, [LEO says GER] that which Loses Electrons is Oxidized, that which Gains Electrons is Reduced.

it isnt always oxygen that does this, a difference of RedOx potential allowing redistribution of electrons is all you need.

mars has a perchlorate problem thus carbon compounds are converted to carbonate via Oxidation when encountering ubiquitous perchloate mineral deposits.

its toxic to carbon based biochemical forms, and destructive to carbon materials, such as carbon fibre; carbon nanotubes; carbon steel; even a lot of keypads.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Pesky Perchlorates All Over Mars:

https://www.science.org/doi/10.1126/science.340.6129.138-b

We learned it as OILRIG: oxidation is loss, reduction is gain

Steel has between 2% and 0.05% carbon, that's not really a lot, particularly when you consider martian colonists will want materials like sugar and polyester that have a much higher carbon content. [1]

There are numerous ways to fix carbon from CO2. If you can grow plants you can make a char out of them which what people used to use to reduce iron and add carbon as an alloying elements. There is a huge amount of research on turning CO2 into CO so that it can be mixed with H2 (then they call it syngas) and then build up larger molecules such as methane, methanol, gasoline, fats, etc.

https://news.mit.edu/2024/engineers-find-new-way-convert-car...

It's not a question of being able to do it but instead doing it better, cheaper, harder, faster, ...

The funny thing about reduction of iron (and many metals) is that it can be done with either of the two ingredients of syngas, CO [2] or H2 and either way you get the oxide CO2 or H2O as a byproduct. If space colonists think that volatiles are precious they'll practice chemical cycling, turning those back into reactive CO or H. On the moon or asteroids I'm pretty sure people would think either C or H2 is precious and wouldn't waste it, I am not sure about Martians (e.g. if you can get CO2 out of the atmosphere it might not seem like a crime to vent it)

[1] people think "technology" and they think "metals" but actually a lot of what you want is made of carbon, hydrogen, oxygen and nitrogen (CHON)

[2] what a blast furnace uses

Yes, the problem is likely not in getting enough carbon (though a kiloton of steel would require several tons of it), but rather having a mass production process advanced enough to precisely control it. Almost all heavy equipment would have to be bootstrapped on Mars, mostly from the inevitably subpar local materials, and ith access to energy that's worse than on Earth: no fossil fuels, no hydro-energy, much less sunlight.

Everyone who's seriously considered space colonization has come to the same conclusion that Eric Drexler did -- you need to have some kind of system that can make absolutely everything with as small a population supporting it as possible.

You've got the problem that there's nothing that could manufactured on Mars that would be worth bringing back to Earth. If a Martian colony was dependent on Earth for anything it would expect to get its resources cut off at any time, and even if you can get spare parts and stuff from Earth the turn-around time counting the synodic period and transit time will always be several years. See

https://en.wikipedia.org/wiki/The_Martian_Way

I think it could be possible with some combination of synthetic biology, fermentation, flow chemistry, 3-d printing and such. It's a good northstar for research into "advanced manufacturing" which could come in handy here on Earth.

Honestly I think one of the possible premier uses of orbital (though not Martian) resources would actually be agriculture. Limiting biological contamination and maintaining sterile environments, unlike other industries, can produce a value-added product compared to the inputs.

Also there's at least a plausible mass trade off - a space borne habitat structure doesn't need to support its own weight against gravity, so you might be able to trade favorably on the launch costs (e.g. grow crops in a big inflatable dome under hydroponic conditions). Certainly it would make enforcing quarantine easier.

Large structures and LEO do look like the closest you could come to the LEO dream. The atmosphere for a baby Bernal sphere that has a usable area of 35 acres would take about 15 starships to send up which would be like getting 1 starship load to the moon. Building something like that which is a simulation environment for Mars might be cheaper than going to Mars.

I have a fairly generic reaction to this.

Make metals at the top of Everest. Then we’ll talk.

You’re right, that is a generic reaction. And completely ignorant of the different chemistry, environment, and context.

Really? Seems like building a manufacturing capability on Everest or Antarctica or a Saharan dune sea would be easier in every single way.

While there is a lot that could be said about this at the object level, the correct answer is “so what?”

You're right, it would be easier in every single way.

It would also be different enough that it's not a useful or meaningful comparison. You might as well say "bake a cake while standing on stilts, then we'll talk".

By the way, humans have been mining, and on-and-off purifying, iron from the Saharan dune sea for a thousand years. https://en.m.wikipedia.org/wiki/Zou%C3%A9rat

OK. As a warmup exercise, make metals at the top of Everest. Then we’ll talk.

On the topic, the ANTHROFUTURISM YouTube channel is excellent for learning about building on the Moon using regolith: https://www.youtube.com/@Anthrofuturism

There’s a good recent book series about this by Daniel Suarez called Delta V (in the first book they process regolith from an asteroid; in the second book its on the moon; presumably the unreleased third book is on Mars).

It's a given that if you're taking space exploration seriously, you need ISRU. You can't ship everything to Moon or Mars from Earth - you need to learn how to process and refine local materials.

This is the key advantage of going to Mars or Moon surface, as opposed to operating a space station. A space station exists in a vacuum. Surface bases have access to local materials.

Sadly, very few planned space missions have this kind of ambition. That recent proposal US had about putting a nuclear reactor on the Moon was at least a step in the right direction - if you're bringing an entire reactor, that means you're establishing a permanent base, complete with an industry that would generate the demand for power.

>Swinburne and CSIRO researchers have successfully made iron under Mars-like conditions, opening the door to off-world metal production.

Not trying to be pedantic but really curious, it should be off-earth not off-world, right?

Off-world meaning that the iron production is made by alien not human.

Google defines (citing Oxford Languages) offworld as:

* away from earth or (in science fiction) from a place treated as the native world.

* involving, located in, or coming from a place outside one's native world or planet.

While Wiktionary defines it as:

* (chiefly science fiction) Not on Earth.

* (chiefly science fiction) Away from Earth.

https://en.wiktionary.org/wiki/offworld

To me that sounds like Mars would qualify

This is so exciting. I really hope Musk succeeds in bringing humans to Mars so all this tech-tree can finally be unlocked!

Being assigned to Mars will be the new "sent to Siberia".

Fun Fact: There is a 0% chance we will go to Mars this century! Elon's hyperloop is more realistic, and RFK Jr's medical theories are safer than the journey would be.

Would you like to place a bet on it?

Go and stay is 0.

Yes, I should have specified that, as that's what I meant.

I'm not sure of the point in sending a human there and back without a colony, but that wouldn't stop us if we find an emotional reason. The poor astronaut will die young after their return, of course, but that's true for many occupations already.

Not surprised at the downvotes I got. "We're going to live out there! Soon!" is baked into us by every TV show, movie, and book around us, it seems. But it is nowhere as easy as "2001: A Space Odyssey" promised. Not even as easy as "Space 1999".

Would you be willing to enter a 100'000'000-to-1 bet? If we make it before the century, you make me a millionaire and if we don't I'll give you a dollar. Should be within your risk tolerance given you think the chance is 0.

I'll introduce you to the concept of rounding off digits soon.

There is a 0.0% chance you understood that.

lack of touching grass seems to be a prohibitive factor; besides the radiation

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