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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 q

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.

ceejayoz 2y ago
Mars isn’t radioactive. A reactor would still need shielding.
- greenbit 2y ago
  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.
  - ceejayoz 2y ago
    Barring significant progress in robotics we'll still need humans to maintain the thing.
    - JumpCrisscross 2y ago
      > 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.)
- jujube3 2y ago
  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.
  - ceejayoz 2y ago
    Mars is regularly irradiated by solar radiation. This is very different from being radioactive.
    - JumpCrisscross 2y ago
      > Mars is regularly irradiated by solar radiation. This is very different from being radioactive Yup. Mars is radioactive to the degree empty space is.
    - jujube3 2y ago
      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.
JumpCrisscross 2y ago
> What is wrong with launching a water-cooled reactor to Mars? Water is heavy and difficult to replace if lost for whatever reason.
- throwaway11460 2y ago
  There is water on Mars, why not use it?
  - JumpCrisscross 2y ago
    > 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.
    - throwaway11460 2y ago
      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.
      - JumpCrisscross 2y ago
        > 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.

ceejayoz 2y ago

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

greenbit 2y ago
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.
- ceejayoz 2y ago
  Barring significant progress in robotics we'll still need humans to maintain the thing.
  - JumpCrisscross 2y ago
    > 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.)
jujube3 2y ago
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.
- ceejayoz 2y ago
  Mars is regularly irradiated by solar radiation. This is very different from being radioactive.
  - JumpCrisscross 2y ago
    > Mars is regularly irradiated by solar radiation. This is very different from being radioactive Yup. Mars is radioactive to the degree empty space is.
  - jujube3 2y ago
    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.

JumpCrisscross 2y ago

> What is wrong with launching a water-cooled reactor to Mars? Water is heavy and difficult to replace if lost for whatever reason.

throwaway11460 2y ago
There is water on Mars, why not use it?
- JumpCrisscross 2y ago
  > 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.
  - throwaway11460 2y ago
    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.
    - JumpCrisscross 2y ago
      > 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.