>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.

"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

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.

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.

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.

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

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

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

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

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.

delta-V happened to asteroid folks.

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

> 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?

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.

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

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

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

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

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.

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

Would you like to place a bet on it?

Go and stay is 0.