If I am understanding what you are asking, then yes - in theory, one (ok - an advanced species; note, that is not humans - not yet) could consume all the materials of the Earth, convert them, and turn them into "things" that are in space; in short, strip mining the Earth until it was completely gone.
Certainly that could be done in theory - but the amount of energy it would take would be of a scale we haven't even begun to barely imagine. We certainly aren't generating that amount to do it, or harnessing such amount either.
So practically, the answer to your question is "no"; what we "send away" from the Earth is negligible.
In order for you to understand why, I encourage you to research the scale of things you are trying to understand. The Earth is big - really big. It may not seem like it, but it really is. What might cause you both a bit of "fright" and "wonder" though is the atmosphere: Compared to the Earth, the atmosphere is thin - very thin. For instance, if you imagined a baseball as the planet Earth, the atmosphere would be a very thin layer over the surface of the baseball, much lower than the ridges formed by the lacings.
Then you compare the scale of the Earth (it's size) to that of say - Jupiter (heck, just the Great Red Spot!). Then compare Jupiter's size to the size of the Sun (hint: Jupiter is tiny).
Then compare the Sun to the size of our nearest neighboring star. Then compare the size of that to other known stars.
Eventually you get to the size of our galaxy - which is an insanely large collection of stars...
Then take a look at the Hubble Deep Space image - and realize that all of those points, far in the background - that all of those are each a galaxy, separated by vast distances from each other...
...and then realize that what we see on that image is only a tiny amount of the whole universe.
The Earth? Compared to all that, we aren't even the size of a quark on the butt of a bacterium...
I would be more worried about the opposite occurring -- all these initiatives to mine asteroids are introducing new inputs into the closed loop that is the Earth's physical manifestation
We already have a lot of mass of random junk falling into the atmosphere from space all the time. A result from a quick google search:
> Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons. Most of this mass would come from dust-sized particles.
I guess this means the Earth gets slightly bigger and gravity becomes slightly stronger over time, but it's a much smaller effect than, say, the ocean's tides creating drag that slows the rotation of the Earth.
Presumably, the materials we mine and bring back aren't going to have the same composition as micrometeorites, since space gravel exactly isn't economically valuable. As long as we aren't bringing back super toxic or environmentally damaging stuff that's rare on Earth, I'm not too worried. Also, I expect all but the most valuable elements (e.g. gold, platinum) will be re-used in space to build infrastructure.
It's interesting that a robust space launch economy could compensate for the thousands of tons of annual space gravel, and cause the Earth to maintain its mass at a constant value.
In terms of energy, it'd take about a week's worth of the sun's total power output to disassemble the Earth. So on one hand yeah, it'd be very doable for an advanced civilization to deplete the Earth's resources that way, but on the other we're pretty far from that level.
There's obviously an upper limit but we are very far from reaching that. Satellites are made up of many components much of which is aluminum most composed of bauxite. Apparently we have a lot reserves and are able to meet demand for quite awhile into the future.[1]
Worst case we can always recycle that space junk but it's still way cheaper to recycle what we have on our surface before we run out of mines or grab stuff from orbit.
Certainly that could be done in theory - but the amount of energy it would take would be of a scale we haven't even begun to barely imagine. We certainly aren't generating that amount to do it, or harnessing such amount either.
So practically, the answer to your question is "no"; what we "send away" from the Earth is negligible.
In order for you to understand why, I encourage you to research the scale of things you are trying to understand. The Earth is big - really big. It may not seem like it, but it really is. What might cause you both a bit of "fright" and "wonder" though is the atmosphere: Compared to the Earth, the atmosphere is thin - very thin. For instance, if you imagined a baseball as the planet Earth, the atmosphere would be a very thin layer over the surface of the baseball, much lower than the ridges formed by the lacings.
Then you compare the scale of the Earth (it's size) to that of say - Jupiter (heck, just the Great Red Spot!). Then compare Jupiter's size to the size of the Sun (hint: Jupiter is tiny).
Then compare the Sun to the size of our nearest neighboring star. Then compare the size of that to other known stars.
Eventually you get to the size of our galaxy - which is an insanely large collection of stars...
Then take a look at the Hubble Deep Space image - and realize that all of those points, far in the background - that all of those are each a galaxy, separated by vast distances from each other...
...and then realize that what we see on that image is only a tiny amount of the whole universe.
The Earth? Compared to all that, we aren't even the size of a quark on the butt of a bacterium...