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Those are big, and heavy. https://www.oregon.gov/energy/safety-resiliency/Pages/Naval-...

> The submarine reactor compartments that have been taken to Hanford are about 33 feet high and 40 feet in length. They weigh between 1,130 and 1,680 tons. Eventually, the Navy may deactivate its Ohio class submarines in the same manner. Those compartments would be much larger and heavier.

Submarines don't have to get them into orbit.



In case you're serious, nobody is suggesting launching a water-cooled reactor to Mars. Between the idiot ends of the power-source spectrum bounded by, on one end, a U.S. Navy PWR and, on the other end, Martian Aramco, we have the reasonable options of solar power, batteries, RTGs and fission-powered Stirling engines [1][2].

[1] https://www.nasa.gov/directorates/stmd/tech-demo-missions-pr...

[2] https://www.nasa.gov/tdm/fission-surface-power/


I think solar's the far more likely option, yes. Cheap, light, low-maintenance. Maybe fuel cells for night.

RTGs aren't gonna power a good-sized base; they're a few hundred watts at best.

edit: I very much hope Kilopower pans out.


What is wrong with launching a water-cooled reactor to Mars? Or more likely launching the materials needed to build it. The active components of a reactor are quite tiny -- most of the bulk is in the shielding, which won't be necessary on an already radioactive planet like Mars.


> What is wrong with launching a water-cooled reactor to Mars?

Water is heavy and difficult to replace if lost for whatever reason.


There is water on Mars, why not use it?


> There is water on Mars, why not use it?

It's expensive. Every gram takes tremendous resources and energy to extract. It would be like using antimatter for a small-town fireworks show.


If the nuclear reactor was the only thing that needs water, yeah. But if we're at the point of installing a nuclear reactor on Mars, I guess we would also be actively mining and processing water in large quantities.


> if we're at the point of installing a nuclear reactor on Mars, I guess we would also be actively mining and processing water in large quantities

A reactor should be among the first things we put down, ahead of the arrival of humans. And even if we’re processing lots of water, it would be a long time before it’s so abundant that sequestering (and irradiating) such a large amount of it is cheaper than other methods.


Mars isn’t radioactive. A reactor would still need shielding.


Only if you intend to stand near it while it's running. Not trying to be glib, just pointing out that at least initially, there might not be any humans near. Admittedly, radiation might be a bother for high density electronics (CPUs, RAM, etc), but maybe it'd be cheaper to shield the bot-brains. Bots could rely on the power for a few years and when the humans get there, if nothing else you could drop all the rods in and let the rad flux die down.

I know, I wouldn't want that in my back yard either, but Mars is exactly nobody's back yard at present. Bootstrapping a (necessarily!) technological civilisation on another planet is not an un-risky business.


Barring significant progress in robotics we'll still need humans to maintain the thing.


> we'll still need humans to maintain the thing

Sure, but you're not going to need major shielding for the first few hundred reactors on the planet. Putting the stuff that requires maintenance away from the reactor will be enough for a few decades. (Put simply, the aspiring interplanetary powers who insist on heavily shielding their reactors aren't going to be releavant on the ground. You can launch a second reactor for the cost of one's shielding.)


Dirt works fine for shielding, when you live on a planet whose soil is already toxic to life. And yes Mars is radioactive, because it has no magnetosphere. Especially when there is a solar flare.


Mars is regularly irradiated by solar radiation. This is very different from being radioactive.


> Mars is regularly irradiated by solar radiation. This is very different from being radioactive

Yup. Mars is radioactive to the degree empty space is.


Not really. Being regularly irradiated makes you low-level radioactive.

After all the pedantry is out of the way, the point is that humans on Mars already have to deal with radioactivity, which makes using nuclear power a no-brainer.




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