Re: Solar power's "bright future"

['Chris de Morsella' via Everything List]

________________________________
 From: LizR <lizj...@gmail.com>
To: everything-list@googlegroups.com 
Sent: Friday, June 20, 2014 6:10 PM
Subject: Re: Solar power's "bright future"
 




>>That raptor rocket surely doesn't have much higher delta V than, say, the 
>>Saturn 5? No chemical reaction is going to be that much more efficient, no 
>>matter that you turn it into a superheated flying bomb. Surely for human 
>>exploration beyond the Moon you really need (a) a moon base, (b) and orbital 
>>assembly plant supplied from the moon base, and (c) some form of nuclei/ion 
>>propulsion for your long haul space craft (which also need shielding, of 
>>course!)

I agree -- nothing I have heard about really improves on the chemical potential 
of H2(liquid)/LOX. The advantage of LNG is not that it is pound for pound a 
better fuel/oxidizer combo than liquid hydrogen/LOX (Saturn 5), because it 
isn't, but rather because LNG fuel allows for significantly longer longevity of 
the rocket fuel tanks and rocket motors components themselves. Hydrogen causes 
metals to become brittle; whereas LNG does not (or does not to the degree that 
hydrogen does). On a long duration mission -- say to Mars and back -- it 
becomes rather important that the rocket engine components do not wear out 
prematurely. That would be a real bummer, for the unlucky astronauts.

The innovative aspects of the Raptor engine are not just in terms of the type 
of fuel it uses, but also because it uses separate turbo injection for the LNG 
and LOX using floating bearing (essentially the spinning parts of the turbo 
pump actually are floating on a very thin film of the LOX or LNG. This also 
very significantly improves rocket engine life (those bearings wear out fast). 
And by (apparently) choosing to use separate turbo pumps for the LNG and the 
LOX it removes a catastrophic failure point for designs that employ a single 
turbo pump with a diaphragm separating the LOX from the fuel (whatever it is) 
-- if the diaphragm fails in such a design it is an almost guaranteed 
catastrophic failure.

Again I agree -- if we are ever going to become a space fairing civilization we 
need to learn to live off the land (the land up there). The moon has a very 
much smaller gravity well than planet earth; it just seems to me to make sense 
to get the mass of fuel and LOX at the very least and perhaps other materials 
as well from there (or from NEO asteroids as well)



>>Or use chemical propellant to rendezvous with one of those asteroids I 
>>mentioned, then sit back and wait out the 9 months or so to Mars. (Preferably 
>>installing a permanent base in the asteroid, which effectively becomes a mars 
>>shuttle.)


The asteroid Eros 433  would seem to fit the bill for a transit station. It is 
fairly big (the second largest NEO in fact); it is an Amor type asteroid and is 
a Mars crosser. 

>>I wish I could type this without my hands shaking with excitement. We're 
>>actually trying to go to Mars!!!!!!

I really hope so :)
Chris

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