5 ms·

The cost wouldn't be trivial for powering a mars colony. I'm sure the demand for a colony would scale pretty fast to 100kW or more. Now we are talking about Bi

The cost wouldn't be trivial for powering a mars colony. I'm sure the demand for a colony would scale pretty fast to 100kW or more. Now we are talking about Billions. So I think that your original point that cost for Pu-238 is not an issue for a colony is wrong. Small reactors are a much better option as a single ton of fuel could supply a colony with a few MW for decades. You just have to make sure that the largest part is less than 37 tons so it can be transported with a Long March 9.

avar 9y ago
My original point was that dredmorbius's comment that Pu-238 is in low supply wasn't referencing some law of nature, but a political decision that could be changed. I said they were a "bad idea for general power generation", so I'm not suggesting that they be used to power a Mars colony, but rather that the reasons not to do so don't include Pu-238 being in low supply. We also have a low supply of rockets & other infrastructure to colonize Mars, but we can simply decide to make them. Still, I think any extrapolation of current numbers to say that Pu-238 would be categorically unsuitable for such a purpose is probably premature. Nobody's tried to produce it on a truly industrial scale, which would bring costs down. It has a half-life of around 90 years degrading at 1%/year, so once you produce it it'll power the colony for a long time. It's also around 6% efficient at generating electricity[1], but 100% efficient at generating heat, which is a huge part of energy requirements on Mars when it comes to human habitation. The Curiosity rover generates 120W of electricity but 2000W of heat. 1. https://physics.stackexchange.com/questions/34203/mars-curiosity-power-system https://physics.stackexchange.com/questions/34203/mars-curio...
- dredmorbius 9y ago
  There are laws of nature involved. But also of men, nations, and war. Pu-238 isn't found in nature, but has to be synthesized. The precursor material, U-238 is the most abundant form of Uranium, which is convenient. It's also produce via neptunium-237. The real complication is that the nuclear synthesis processes are also those used for nuclear weapons production, which makes for some serious complications.
  - avar 9y ago
    Those complications only apply to nations that don't have a permanent seat on the UN security council. There are no treaty obligations preventing the US or Russia from making Pu-238.

avar 9y ago

My original point was that dredmorbius's comment that Pu-238 is in low supply wasn't referencing some law of nature, but a political decision that could be changed. I said they were a "bad idea for general power generation", so I'm not suggesting that they be used to power a Mars colony, but rather that the reasons not to do so don't include Pu-238 being in low supply. We also have a low supply of rockets & other infrastructure to colonize Mars, but we can simply decide to make them. Still, I think any extrapolation of current numbers to say that Pu-238 would be categorically unsuitable for such a purpose is probably premature. Nobody's tried to produce it on a truly industrial scale, which would bring costs down. It has a half-life of around 90 years degrading at 1%/year, so once you produce it it'll power the colony for a long time. It's also around 6% efficient at generating electricity[1], but 100% efficient at generating heat, which is a huge part of energy requirements on Mars when it comes to human habitation. The Curiosity rover generates 120W of electricity but 2000W of heat. 1. https://physics.stackexchange.com/questions/34203/mars-curiosity-power-system https://physics.stackexchange.com/questions/34203/mars-curio...

dredmorbius 9y ago
There are laws of nature involved. But also of men, nations, and war. Pu-238 isn't found in nature, but has to be synthesized. The precursor material, U-238 is the most abundant form of Uranium, which is convenient. It's also produce via neptunium-237. The real complication is that the nuclear synthesis processes are also those used for nuclear weapons production, which makes for some serious complications.
- avar 9y ago
  Those complications only apply to nations that don't have a permanent seat on the UN security council. There are no treaty obligations preventing the US or Russia from making Pu-238.