Terraforming Mars-- are we really running out of space?

 
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There you go.
 
The 9th Sage said:
It would have to be a hell of an explosion to knock the moon out of orbit or some such thing.
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It's possible but improbable. I also worry if we get a space presence the carting of minerals from asteroids be transferred to earth. Imagine if a ship lost power while passing the moon or entering orbit and I'm talking a ship that is huge since moving small quantities would not be as profitable and profit and conservation in space will be everything.

I've read a lot of decent sci fi books about this kind of stuff happening and how huge accidents can have implications that can be global in their effect.
 
Well, the force of the rocket (including the explosion) would have to exceed the force of the moon to have any meaningful effect (I'm not sure on the exact math of that, but I think it's the mass of the moon times gravity, anybody better on the inertia of celestial objects than me?). The problem is, that such a rocket would probably disrupt orbit of the earth before it did anything to the moon.

Due to the enormous mass of both the moon and the earth, as well as their gravitational powers, the loss of a rocket or space shuttle and the rocket blast that allows it to exceed escape velocity don't really have a significant enough effect on the planet to really do anything meaningful. Which is the only reason we still have a space program.
 
jdev said:
Well, the force of the rocket (including the explosion) would have to exceed the force of the moon to have any meaningful effect (I'm not sure on the exact math of that, but I think it's the mass of the moon times gravity, anybody better on the inertia of celestial objects than me?). The problem is, that such a rocket would probably disrupt orbit of the earth before it did anything to the moon.

Due to the enormous mass of both the moon and the earth, as well as their gravitational powers, the loss of a rocket or space shuttle and the rocket blast that allows it to exceed escape velocity don't really have a significant enough effect on the planet to really do anything meaningful. Which is the only reason we still have a space program.
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It also matters from what direction the explosion takes place since you would have a much lower effect if it happened right on the side that was the moons present direction. I guess a hit on the side toward the Earth "pushing outwards" or one from behind or some angle from behind that would make it a bit faster and/or give it a lower orbit or higher orbit would cause a huge effect on earth life like plankton and other life forms that depend on the gravity of it to tell them to breed or other things that they have done for millions of years.
 
I asked someone else about it, and this is what I got:

Well sir, I believe the moon has an orbital energy of -m^2g/(2a) where a is the semimajor axis, and it's equal to (for the moon) about 4.5 *10^24 MJ

That's assuming its semi-major axis of 384400 km. Let's change it by 5 km (a distance I run several times a week), to 384405 km.

Well the difference is several decimal points out (more than I typed) but I got something*10^17 megajoules.

So you'd have impart on the order of 10^17 million joules to move its semi-major axis by 5 km

One Joule is the amount of work required to move on Newton one meter. A kilogram is approximately ten Newtons. So that'd be around five hundred thousand of Tsar Bombas, which is the most powerful nuclear weapon ever built. And it was so powerful, the Soviets were like "You know what? Let's not make any more of those."

Also, 5 km is pretty much nothing, the moon shifts its orbit by hundreds of kilometers each year. Basically, the object hitting the moon needs to have a comparable amount of mass. It's like shooting a bullet into a mountain. You're not going to move the mountain unless it's like a 200 ton bullet (and even then, probably not much).
 
So if I'm reading this right, it would be easier to pretty much knock a big hunk off the moon than to actually move it out of orbit enough to matter for us on earth?
 
Very interesting. There was one ridiculous thing I read that someone, who apparently has no idea what they're talking about, wrote. They stated that the moon could be hollow, and that we shouldn't be throwing things at it until they find out. That is a very silly theory if you ask me. By the end of their argument, they were contradicting themselves. lol
 
The moon could only be hollow if it had an incredibly superdense layer of matter beneath the crust. That wouldn't really make sense, since there'd have to be some method for getting whatever was in the crust out, but I'm pretty sure there's no hollow celestial bodies. There'd have to be some matter, even a gas, inside. But we can judge a planet's mass by its gravity, and how likely a planet would be hollow by whether its mass corresponds to its size and the mass of smaller samples of the planet's surface.

Besides, there's never been any actual space missions, because God would knock the rockets out of Heaven and the earth is flat, etc.
 
haha. Besides, I couldn't really see how the moon wouldn't be able to withstand something like that when it works as a punching bag for Earth's protection. Did the person who wrote that not see the craters that litter the moon?
 
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