Zeke Sturm wrote:The problem with that becomes it won't just remain there, since gravity is affected by the weight of an object, which would certainly change if an object became much bigger, and also a rock.
No, the weight of an object is the RESULT of gravity. The mass of an object generates gravity. Once an object is in orbit above the atmosphere, it does not require thrust to stay in orbit. You may be thinking "Well the asteroid will have it's own gravity as well!" and sure, it does. So do you. So does everything. But the asteroid would need to be much, much bigger to have any sort of effect.
The best way to think of an orbit is to think of an object in perpetual free-fall, but 'missing' the planet constantly. It has sufficient forward velocity in the prograde direction to make the vector such that it never actually reaches the planet.
You might want to look at this page for a simplistic example of orbital mechanics Newton thought up.
https://en.wikipedia.org/wiki/Newton's_cannonballIt would require more thrust to PUT it there, but considering one of our current ideas for mining gold and other earth-rare metals is to just go get asteroids and bring them to earth to mine them, it seems like doing this is not that far off. There are already several private companies attempting to work towards this goal, for example, the companies Planetary Resources, and Deep Space Industries.
... what thrust do you think is keeping the moon in orbit?