[ExI] Eyes on the Solar System

Stuart LaForge avant at sollegro.com
Mon Sep 5 19:34:15 UTC 2022

Quoting Spike,

-----Original Message-----
> From: spike at rainier66.com <spike at rainier66.com>
> ...
>> ...On second thought, Stuart, scratch that.  The irony of using a hydrogen
> first stage to lift a kerosene final stage, oh that is killing me...OK then.
> There is a bright side in all this somewhere, but the argument above is an
> epic fail, my apologies, sheesh how embarraskin...spike
> Stuart as I am pondering the problem of carrying humans to Mars, I am
> reminded of the ugliness of some of the solutions one must try.  Like that
> business of lifting a kerosene burning stage using a hydrogen burning stage
> for instance, from an engineering point of view, it is just uglier than
> nudist colony day at the nursing home.

Nothing to be embarrassed about, Spike. Hydrogen is the most abundant  
element in the universe and if we, as a civilization, want to climb  
the Kardashev Scale and reach the stars, then we will have to master  
the collection, storage, and applications of hydrogen. Diatomic  
hydrogen is a tricky little molecule, slips through the tiniest flaws  
in the crystal lattice of the matter that its container is made of. I  
am confident many smart people are working on this.

> The problem is based on the need to fire a delta V from earth orbit, then
> fire an orbit adjust burn when we get to Mars about 8 months later, then go
> play on the surface of Mars for a few days, then when (or if) the humans
> come back, you have another orbit adjust burn to get back to Earth, then
> another burn 8 months after that to insert into LEO to get ready for
> descent, then a descent initiation burn.
> OK so even if you had those huge first stage motors in LEO... you wouldn't
> use them.  Reason: there is no point in hauling all that stuff out to Mars
> where you can't use it because we have no known technology for holding onto
> liquid hydrogen for the 8 months it takes to get to Mars.  So... we need to
> haul low-volatility fuel oxidizer (because can't hang onto LOX that long
> either) so we get hydrazine and nitric acid thrusters for everything after
> we leave Earth orbit.

Long term storage of LOX might be made a bit easier by the fact that  
O2 is paramagnetic. Therefore we might be able to come up a with some  
form of powered LOX storage such as an electromagnetic bottle:


> Oh what an ugly solution that is.

Hydrazine is toxic, unstable, and nasty but it seems to be a  
reasonable way to store hydrogen. I think hydrazine and LOX might be a  
good combo. Has anybody thought of using the nitrogen and hydrogen  
from Hydrazine decomposition as the propellant for nuclear rockets  
like NERVA? Evolution is often ugly and jury-rigged in its initial  
stages with elegance coming later. Besides beauty is in the eye of the  
beholder as they say.

Stuart LaForge

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