Chinese moon landings

[Az]

KH : you sure about those minerals points you made ? I heard the moon was pretty rich with , aluminium , f.e.

and also has that gas in the core ,that we already can use in fusion, with quite a positive energy balance.

[KrazyHorse]

I'm not sure about aluminum, which is often concentrated in regolith, but I thought the Moon was far less rich in the heavier metals than the Earth, giving it a much lower density overall.

[KrazyHorse]

The Earth's Moon is harder to explain. It's so large in comparison to the Earth (as you showed above) that it's very unlikely that the Earth could have captured it unchanged, or formed it in place from leftover material. We also know from rocks brought back from the Moon by the Apollo astronauts that the Moon's composition is quite similar to Earth's in most respects, but that it has much less metal than the Earth does. This makes the capture theory even more unlikely, since a body that formed somewhere else in the solar system is unlikely to have a similar composition at all. The currently favored theory is that a giant impact soon after the Earth formed splattered a large amount of molten and rocky material into orbit. Most of the material would have fallen back to the Earth, but if the size and direction of the impact were within a certain range, enough material could have remained in orbit to clump together and form the Moon. Since metals are heavier than plain rocks, the metal would be more likely to fall back to Earth, while the less dense rock could stay in orbit long enough to form the Moon. So this could explain why the Moon's composition is so similar to the Earth's in most respects, but depleted in metals. Scientists are still working on this theory, and all the details have yet to be fully understood

(emphasis my own)

Taken from http://www.jpl.nasa.gov/galileo/sepo.../ssgraph4.html

[Az]

well, since when do you need heavy materials to build a spaceship?

I also heard it's got a s***load of quartz , for glasses for all those control panels .

seriously though , if the moon is made of light metallic minerals , it should be better , non?

[KrazyHorse]

a) No. Only good for light accel. vehicles. I suppose if you develop some sort of working ion drive this is moot, but even then you're going to need a reusable launch vehicle for the heavy lift at the start.

b) You still haven't shown me where you learned there are substantial aluminum deposits. Silicates are nice, but you need something to hold them all together.

c) You still need fuel, which the Moon most certainly does not have. Fuel makes up 99+% of a rocket's mass. Comets are a good source for this. Grab a few, put them at L-5, electrolyze the water with a big-ass nuclear reactor. Separate, pressurize and you've got a lot of boom saved up.

d) Delta-v is still higher off the surface of the moon than it is from L-5

[Ecthy]

c) I think that doesn't make any sense. ANY sense at all. If you electrolyze water with a nuclear reactor, you probably want to use the components for a fuel cell engine or something similar to it. Heh heh. Enery bilance is the key. Your fuel cell engine will put out water. Which you had just electrolyzed. And for that you needed energy. Heh heh. Heh. Why not use thenuclear reactor for gaining energy for the engine? I mean the way you put it, your spaceship system loses energy...

[Az]

didn't understand your a) point. what were you referring to?

b) I've read it in a number of books , and on TV . ( no , not star trek ). I am working on a nice link for you.

c) we're talking future propulsion systems here. It's quite clear that chemical rockets won't get us far away. And yes, I know that still , fuel will be the complete majority of the overall mass.

L-5 ? I am not familiar with the termin . Is this a certian round orbit around earth ?


after all said and done, moon is still a much easier launch , than earth.

In any case of INTERSTELLAR spaceships, we'd have to colonize an outer region moon. We'd also have to get the materials from there. This seems to be an unbearably heavy task.

But hey, I have a dream.

[KrazyHorse]

c) I think that doesn't make any sense. ANY sense at all. If you electrolyze water with a nuclear reactor, you probably want to use the components for a fuel cell engine or something similar to it. Heh heh. Enery bilance is the key. Your fuel cell engine will put out water. Which you had just electrolyzed. And for that you needed energy. Heh heh. Heh. Why not use thenuclear reactor for gaining energy for the engine? I mean the way you put it, your spaceship system loses energy...

i) Why would you take a nuclear reactor with you? Every pound is critical. Do the seperating first, load ready-made energy up in the form of a hydrogen compound and LOX, light a match

ii) Chemical rockets get you a lot more boom per second than any nuclear-propelled rocket on the table.

iii) I know I lose energy by travelling a circular path, but that's irrelevant.

[Ecthy]

You mentioned a nuclear reactor for electrolyzing water from asteroids.

[Az]

I am still not sure . Where do we want those spaceships to go?

[Ecthy]

(Sid Meier's) Alpha Centauri!

[SociableMartian]

China landing on the Moon? Give me a break, everyone knows China doesn't have the money or the will to launch a Lunar mission. Anyway what would they do when they get there, set up a chain of interplanetary Chinese restaurants???

[KrazyHorse]

Originally posted by Dalgetti
didn't understand your a) point. what were you referring to?

For any heavy lifting you need strong metals with high heat tolerance. That means they have to come from lower down on the periodic table than Al.

b) I've read it in a number of books , and on TV . ( no , not star trek ). I am working on a nice link for you

Still waiting...

c) we're talking future propulsion systems here. It's quite clear that chemical rockets won't get us far away. And yes, I know that still , fuel will be the complete majority of the overall mass

And that means you need volatiles. The moon lacks those.

L-5 ? I am not familiar with the termin . Is this a certian round orbit around earth ?

It's a Lagrange point; a stable point in orbit around the Earth, at lunar distance but 60 degrees ahead (?) of the moon. You put things there and they stay where you left them. Due to the moon's grav. field all other orbits are inherently unstable.

after all said and done, moon is still a much easier launch , than earth

But not as easy as at L5.

[KrazyHorse]

Originally posted by Ecthelion
You mentioned a nuclear reactor for electrolyzing water from asteroids.

Yes, but you leave it at L5 when the spaceship goes. It's the Solar Sytem's biggest gas station.

[KrazyHorse]

Originally posted by SociableMartian
China landing on the Moon? Give me a break, everyone knows China doesn't have the money or the will to launch a Lunar mission. Anyway what would they do when they get there, set up a chain of interplanetary Chinese restaurants???

Not even close to funny, and errant in its assumptions. The Chinese have significant heavy-lift capabilities. They've been launching unmanned stuff for decades, and are centralised enough to easily reach deeply into the public purse to do this.