Re: Hydrogen to the Moon

[EMAIL PROTECTED] (Inquiring minds) writes:

>"Alan Erskine" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
>> There's gobs of O2 on the Moon (~40% by mass of the Moon's surface is
>> oxygen), but hydrogen is still needed to make water (remember, the poles are
>> a long way from an economical-to-get-to equatorial Lunar base, so Lunar ice
>> may not be a viable option in the short term) and also needed for rocket
>> propellant.

>> What is the best way of getting hydrogen to the Moon?  Liquid H?  Methane?
>> Both of these are cryogenic and difficult to store for any length of time,
>> especially LH2.  What about hydrogen peroxide or even ammonia?  Ammonia
>> solves two problems as it would provide hydrogen for water and propellant
>> and also provides nitrogen for crew breathing.  Ammonia is both _fairly_
>> stable and dense when compared to either methane or hydrogen and can be
>> stored in simple plastic tanks (protected from the Sun's heat).
>> 
>> What are the methods of separating ammonia into its constituent gases?

>As an alternative.

>Would polyethylene do the trick. It seems to have high hydrogen
>content, is a easy to handle solid and when burnt will also release
>some carbon, I guess in the form of CO2.

Presuming you have an excess of oxygen with which to burn it, yes.
And polyethylene is probably the best choice as a solid hydrogenous
compound, which is why it sees use in various nuclear applications
that call for maximum H (or low-Z generally) content in a solid
package.

But if your goal is to ship hydrogen to the Moon, it's a pretty safe
bet that the best way to do it is to ship hydrogen to the moon.  The
most conservative design for a hydrogen tank suitable for the trip,
even accounting for LH2's low density and cryogenic nature, is going
to be enormously lighter than the lightest batch of atoms suitable
for binding H into a more tractable form.  The best case for that
latter strategy is that you get 25% hydrogen and 75% other stuff,
which ratio will be approximately *reversed* for a simple tank of
LH2.

And yes, most launchers have payload fairings that will hold even
so fluffy a cargo as a full weight load of LH2.


Now, if you specifically *want* a little hydrogen and a lot of
carbon/nitrogen/whatever on the Moon, you may find it worthwhile
to ship methane/ammonia/whatever.  But if it's hydrogen that is
your bottleneck, you ship LH2.


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