Today I was having a discussion with several people, some I know well, some not so well, and some not at all.

We were talking about the plans to return to the Moon by 2020, and the missions between now and then, to scan for Minerals and other valuables, then it was mentioned that if all these things where removed from the Moon, wouldn't this change density and therefore, could this change the Moons orbit?

I have to admit, this question left me stumped for an answer, because I don't know, thinking about it more and more, surely it would definitely have an impact?

Taking millions upon millions of tons of the Moons mass, and this has to include water used for drinking and the production of building materials, and using metals etc to build ships intended in the exploration of the Solar System and beyond.

All said if a profit can be made they will use and remove it.

Could this have dire consequences for our reliance on the Moon, for tides and weather, I know the Moon plays a huge part in our Planetary climate, what effect would a shift in our Moons orbit have on us here on Earth?

The effects might take a long time to alter the Orbit, wouldn't it also have an effect on the Moons gravitational pull on tides, therefore creating a definitive change in weather patterns and sea currents?

It would be great to have some insight into this, as well as a welcome break from Politics.

So please give your opinions, as far as I am aware this question has not been asked, I cant find anything on the ATS search engine.

Would there need to be a limit on mining? surely it cant be allowed to become a free for all.

According to several websites, The mass of the Moon is about 7.35x10^22 kg, although this does slightly vary depending on source.

I don't know the actual math of it, but I think you are right. Here's my uneducated mind trying to work it out - some please correct me!!

-The moon and earth are locked by gravity
-gravity is a constant, but I believe larger mass can exhibit a stronger gravitational pull?

So, if the moon were significantly reduced in mass, then earth would pull on it stronger? or maybe it wouldn't be enough any more to keep the 2 locked and the moon would go drifting off...

I hope someone who knows better comes in here!

[edit on 10/31/2008 by CeltAngel]

Well, seeing that I am a physics major I should know but I am just starting the introductory classes so I will give it a whirl.

According to my book, there is a center of mass created by the earth and moon. This center of mass is dependent on the masses of the earth and the moon. This means it is actually the center of mass of the earth-moon system that is affected by the sun's gravity.

"The center of mass of this system orbits the sun as if all the mass of the system were concentrated at that point." - Fundamentals of Physics 3rd Edition, Halliday & Resnick

This should at least prove that the center of mass of the earth-moon system would change, since the moon would be losing mass. This should mean that the moon would in fact move further away from the earth but that is just a guess. However, if that mass is merely transferred to the earth, I THINK that it would balance out once the material from the moon is then placed on the earth, thus allowing the system its original center of mass.

Maybe this is just too basic or even parts are incorrect but I am pretty sure that answers some of your question.

EDIT: I am really tired so the moon may actually move toward the earth. If I find out, cause I am reading it right now, I will let you know...



[edit on 31-10-2008 by Unlimitedpossibilities]

Changing the mass of the moon wouldn't change it's orbit, but the act of taking things off of the moon does. If mined goods from the moon were shipped off from the moon in equal amounts from two spaceports on opposite sides of the moon, then the forces would cancel out. If you could launch things off the moon with some kind of scifi reactionless drive, it wouldn't change the moon's orbit.

It doesn't matter how much the moon masses because the acceleration due to gravity doesn't depend on mass. The force due to gravity depends on mass, but in an orbit, it all cancels out, so all that matters is the orbital radius, gravitational field, and orbital velocity of the satellite.

reducing the mass of the moon would reduce the magnitude of the tides, though. The quantity you'd have to remove from the moon to do anything remotely measurable would be unimaginable, though.

wouldn't it remain the same. i mean if the moon gets heavier, wouldn't it remain in the same place i mean im no expert but wouldn't it be that the moon would be the same distance as it originally is and thus the same gravitational pull would remain intact

I've been making a few phone calls about this, it seems that at first it wouldn't have much of an effect, but over time, say if we were to colonise mars, or go off into space, we would be taking elements from the Moon as it would be easier than launching them into Earth orbit.

I read that for space exploration to work on a large scale they would be looking to build vehicles on or near the Moon, and added to that materials being shipped for building the first bases etc, all those materials would permanently leave the moon, and that is not taking into account shipments to earth.

I would imagine over a long period of time, the amount of material removed would become immense, and with nothing being put back, maybe an unforeseen problem some time in the distant future.

I shall do some more digging tomorrow, thinking about this is giving me a headache lol , I can make a few more calls and see if i can find out if there has been a study made, I might try and find an e-mail address for a NASA question and answer person somewhere.

If anyone can help with an e-mail address i can try can you post it please?

I don't think it would be cost-efficient to even mine gold on the moon at $1000 an ounce, let alone mining something like iron, copper, etc.

First you need to do an in-depth survey to see what is there, which is an expensive and consuming process even here on Earth. Then you need a cost-effective way to keep operations running, and get the material back to Earth.