[ExI] Space Mining

[Stuart LaForge]

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