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.
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.
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.
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-curio...