[ExI] Space Mining

[Ben Zaiboc]

On 18/10/2020 18:56, Stuart LaForge wrote:
> Quoting Ben Zaiboc:
>
>
>> On 17/10/2020 10:37, John Grigg wrote:
>>> Water will be the new gold thanks to its crucial role in sustaining
>>> life, as well as the fact it can be split into hydrogen fuel and
>>> oxygen for breathing.
>>
>> Hm, if you're going to breathe the oxygen, how do you burn the hydrogen?
>> And vice-versa.
>
> You are assuming a chemical rocket. Nuclear rockets don't need to 
> combust hydrogen, they just need heat it up enough to ionize and exert 
> thrust through a nozzle. Superheated hydrogen atoms and ions provide a 
> higher specific impulse than the water molecules that are the 
> propellant in traditional liquid fuel chemical rockets because the 
> lower particle mass allows for higher propellant velocities for a 
> given amount of energy.
>
>> I think you'd either have to waste a lot of hydrogen (or use it for
>> other purposes), or get oxygen from rocks.
>
> Water might be a compact way to store both hydrogen and oxygen for 
> long trips, but it requires a significant amount of electrical energy 
> to decompose into hydrogen and oxygen. Of course water is important 
> for life support also, so perhaps it would more prudent to harvest 
> hydrogen from the solar wind and interstellar medium and save water 
> for life support.
>
> Stuart LaForge 


Yes, good points. But, to niggle, I wouldn't call it 'fuel' when it's 
actually 'reaction mass'. Water is also good for radiation shielding (as 
is hydrogen if dense enough).

Not that I think any of this is really relevant, though, because space 
is not a good place for biology. But I've voiced that opinion enough 
times now. It seems that space colonisation (by biological humans) is a 
topic like uploading (except in reverse). No real point arguing about 
it, given people's resistance to logical argument.

-- 
Ben Zaiboc

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