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On 18/10/2020 18:56, Stuart LaForge wrote:<br>
<blockquote type="cite"
cite="mid:mailman.164.1603043773.3037.extropy-chat@lists.extropy.org">Quoting
Ben Zaiboc:
<br>
<br>
<br>
<blockquote type="cite" style="color: #000000;">On 17/10/2020
10:37, John Grigg wrote:
<br>
<blockquote type="cite" style="color: #000000;">Water will be
the new gold thanks to its crucial role in sustaining
<br>
life, as well as the fact it can be split into hydrogen fuel
and
<br>
oxygen for breathing.
<br>
</blockquote>
<br>
Hm, if you're going to breathe the oxygen, how do you burn the
hydrogen?
<br>
And vice-versa.
<br>
</blockquote>
<br>
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.
<br>
<br>
<blockquote type="cite" style="color: #000000;">I think you'd
either have to waste a lot of hydrogen (or use it for
<br>
other purposes), or get oxygen from rocks.
<br>
</blockquote>
<br>
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.
<br>
<br>
Stuart LaForge
</blockquote>
<br>
<br>
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).<br>
<br>
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.<br>
<br>
<pre class="moz-signature" cols="72">--
Ben Zaiboc</pre>
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