posted
Okay, I've heard it said that we can get oxygen and water and all sorts of fun stuff from the lunar rocks. But what about fuel? Specifically, rocket fuel? What we use now is mostly fossil-based, IIRC, but is there anything on the moon that can be used to propel a reasonably large body into its orbit?
-------------------- "This is why you people think I'm so unknowable. You don't listen!" - God, "God, the Devil and Bob"
Registered: Mar 1999
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posted
Without looking it up, I thought that rocket fuel was a mix of liquid oxygen and hydrogen, and not a "fossil fuel." Combustion yields simple steam....
Registered: Mar 1999
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posted
Regolith (lunar soil) is about 40% oxygen, so there's your air and part of your fuel. Hydrogen, nitrogen, neon, and lots of other elements are the product of solar wind particles, and imbed themsleves in th unprotected lunar soil. Everything you need to live on the moon is quite literally in its dirt - the only thing that's needed is a practical way to extract it all.
Of course, if it is ever proven that there is ice on the moon, that basically solves all our problems.
posted
Conversely, if the water is not there, getting enough hydrogen for rocket fuel (any type of fuel, be it pure H2 or a hydrocarbon of some sort) will be difficult. You could of course import methane, as it's roughly as easy to move around as water and also provides some useful carbon but not the extraneous oxygen.
If imported, pure hydrogen would still be a fossil fuel - most of the hydrogen used industrially nowadays is produced from hydrocarbons you get from crude oil.
And if you can catch the solar wind, you might want to harvest helium 3 instead. That makes for practical fusion fuel - and once you have practical fusion, you can forget about rocket fuel. Just fill the tanks with moondust, use the fusion engine to power up a giant electromagnetic coil, and have that spit the moondust out like a rocket exhaust. A massive ion engine like that would probably be a relatively cheap and ecologically friendly drive system for lunar-based spacecraft.
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Christ. If Omega didn't know that rocket fuel wasn't fossil-based, God only knows what Bush thinks shuttles run on. He may think the continuation of the space program depends on his securing Iraq's oil reserves. . .
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Lee, you're being an idiot, and an unproductive one at that. Stop it. Now.
Now to reply to the legitimate posts...
It just occured to me: once you take care of overhead (i.e. the craft), most of the cost of space travel is the fuel. IF you could extract fuel from the moon, you'd have a practically unlimited source, in a low-gravity vacuum environment, where it was relatively easy to get it to Earth orbit for later use. And no pesky biosphere to worry about, either. And on top of it all, you'd have excellent conditions for various types of solar power to run any equipment necessary.
So again, is this doable, either practicallly or theoretically?
-------------------- "This is why you people think I'm so unknowable. You don't listen!" - God, "God, the Devil and Bob"
Registered: Mar 1999
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posted
...Not only that, but the greatest amount of fuel is needed simply to accelerate a rocket away from Earth (attain "escape velocity"). Therefore, if you can launch a spacecraft from a lower-gravity installation -- like the moon -- then you'd need a heck of a lot less fuel for maneuvering.
IIRC, that's one of the long-range purposes of the ISS, isn't it? A launch base for other ships? (Kinda like the "commute" in "2001" -- first Floyd took the space plane up to the station, then took the space-only ship over to the moon.)
-------------------- “Those people who think they know everything are a great annoyance to those of us who do.” — Isaac Asimov Star Trek Minutiae | Memory Alpha
Registered: Nov 2000
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No one gets to call people idiots here except for me.
Registered: Mar 1999
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OnToMars
Now on to the making of films!
Member # 621
posted
quote: Therefore, if you can launch a spacecraft from a lower-gravity installation -- like the moon -- then you'd need a heck of a lot less fuel for maneuvering.
If you want to fly to San Francisco from New York, would you rather go straight there or instead stop off in Chicago?
If you had to stop somewhere, would you rather stop off in San Jose or Orlando?
-------------------- If God didn't want us to fly, he wouldn't have given us Bernoulli's Principle.
Registered: Jun 2001
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posted
I don't get that one. May just be my general fogginess today, though. Could you clarify what you're getting at?
-------------------- "This is why you people think I'm so unknowable. You don't listen!" - God, "God, the Devil and Bob"
Registered: Mar 1999
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It's an issue of relative gravity and the force required to counteract that gravity. In null-gee, all you need is a little "push" to change your direction. If you're trying to launch from Cape Canaveral, you need two massive solid rocket boosters just to reach orbit.
Or, to be more specific, it's one of Newton's laws: an object in motion will stay in motion, unless it's acted upon by another force. In this case, a ship that's "nudged" by a thruster change will head for the moon from out of orbit, but if you "nudge" the space shuttle from the pad, it ain't gonna go nowhere because gravity is continually counteracting that nudge.
-------------------- “Those people who think they know everything are a great annoyance to those of us who do.” — Isaac Asimov Star Trek Minutiae | Memory Alpha
Registered: Nov 2000
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posted
I'm not quite sure what you're getting at either, MinutiaeMan. It sounds like you're talking about the absence of air resistence or some other source of friction in space, not gravity. A ship in orbit of the Earth isn't beyond her gravitational influence, after all. Just the opposite.
Registered: Mar 1999
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posted
Basically you two are just talking at cross purposes. Afterall, this isn't rocket science. Heh. Yes something in orbit is still under the Earth's gravitational influence, it just happens to be going forward fast enough that it falls at the same rate that the Earth is curving. Hence free-fall. If you want to be really picky, practially anything in the universe is under the Earth's gravitational influence, the strength of gravity is inverse squared, but it never hits zero. But thats just being picky.
All he's trying to say is that most of a spaceship (today) is fuel. The same spaceship launched from a space station will spend less fuel pulling away from Earth, and more fuel actually speeding up, than the same spaceship launched from Earth, which has to burn much of its fuel just to counteract the Eath's pull, let alone accelerate.
Registered: Mar 1999
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posted
Now, now . . . no fighting over rocket fuel.
Some rockets have indeed burned fossil fuels "directly", others haven't. Goddard's rockets burned gasoline, and Saturn V's (and some newer rockets like the Atlas (I think that's the one)) burned kerosene. And, as mentioned, the shuttle main engines burned hydrogen, commonly obtained from fossil fuels . . . though other sources for it are available, especially in space.
-------------------- . . . ceterum censeo Carthaginem esse delendam.
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