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In The Time Machine (Guy Pearce version), they manage to literally break up the Earth's moon with obviously disastrous results and I believe they were just building underground structures.

I am wondering if massive mining operations, shipping ore to Earth and thereby not just decreasing Luna's mass but also increasing that of Earth, could cause snowball affect on the orbit -- perhaps Luna would settle into a lower or higher orbit or maybe the decrease in Lunar mass is offset by increase in Earth's mass. But obviously some mass would be lost.

Anyway, given the immense masses involved, maybe we could not accidentally or even deliberately affect the orbit -- the latter I would not bet on, concerted effort involving a lot of nuclear explosions I bet could cause the orbit to decay but I see doing so pretty unlikely.

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    $\begingroup$ Mining is all about "take the valuable stuff and as little else as we can , leave the vast, vast majority of the rest of what we dig up as close to where we found it as convenient/profitable/legally required." There isn't a conceivable situation where "ordinary mining activities" remove a non-negligible fraction of the mass of the Moon from its surface. $\endgroup$
    – notovny
    Jan 5 at 19:10
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    $\begingroup$ I'm sure this is a duplicate but I can't find it. $\endgroup$
    – GdD
    Jan 5 at 19:37

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Could we by ordinary mining activities, affect the Lunar orbit. No we could not. Even assuming the human race had become totally deranged it would not be possible to change the orbital characteristics of an astronomical body such as the Moon to any significant extent it is just too big. There are too many orders of magnitude of mass involved and all humanities efforts are just too puny.

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  • $\begingroup$ my thinking was that the earth and luna exist in sort of a precise equilibrium but if that were the case, what of meteorites hitting the lunar surface? clearly there is some forgiveness, not the right word but close enough, that allows the orbit to remain undisturbed despite changes in mass. but deliberate attempts using h-bombs might cause problems, i was very impressed at the energy of the tsar bomba. we could maybe cause problems by concerted effort, but then, why would we do this? $\endgroup$
    – releseabe
    Jan 6 at 0:49
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    $\begingroup$ To put some numbers to the scale: the Tsar Bomba made a fireball about 8 km across. If it could dig a hole that size in moonrock (which it probably can't) it would contain about 300,000,000 (3 * 10^8) tonnes of rock. In 2019, humanity mined about 3,200,000,000 (3 * 10^9) tonnes of metal. These are big numbers but they pale in comparison to the mass of the Moon, around 73,420,000,000,000,000,000 (7 * 10^19) tonnes - ten billion times greater. It would take millions of years of mining or millions of Tsars Bomba to even make a dent. $\endgroup$
    – Cadence
    Jan 6 at 8:55
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    $\begingroup$ I think the overall sentiment here is totally correct, although an interesting side note is that it is actually quite hard to determine the future stability of the solar system, as evidenced in papers like this where even 100,000 years of guaranteed stability is a rather involved process. And since chaotic systems have extreme dependence on initial conditions, maybe some distant future setup of the planets would be pretty different because of this. However for time scales we care about, this doesn’t matter, and is more just a fun thought $\endgroup$
    – Justin T
    Jan 6 at 9:06
  • $\begingroup$ Also, for a 2 body system, $(2\pi/T)^2=GM/a^3$, where $T$ is the period, $a$ is the semi-major axis, and $M$ is the total mass. So shuttling mass between the Moon & Earth (and treating them as an isolated system) doesn't affect $T$ or $a$, it just changes the Earth & Moon locations (minutely) relative to their centre of mass (which is inside the Earth). $\endgroup$
    – PM 2Ring
    Jan 6 at 16:11
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    $\begingroup$ I doubt that the Tsar bomba would dig a crater even a km deep and most of the material would land back on the Moon. Trying to effect the Moons orbit by use of hydrogen bombs would be a bit like trying to steer an elephant with a peashooter. $\endgroup$
    – Slarty
    Jan 6 at 17:05
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A "mere" two billion tons will have a measurable effect on the Moon's orbit

Could we by ordinary mining activities, affect the Lunar orbit?

It depends on what one's definition of "affect" is. Where gravity is involved, everything pulls on everything. [Dust can find itself in orbit around a satellite or space station for example. See https://space.stackexchange.com/q/40585/12102 and all the other related questions linked there.

So whether we realize it or not, when we ask "Can X affect Y?" we are probably really wondering if there is a measurable effect or not.

Currently the Earth-Moon distance is being measured and its rate of change tracked over time to the order of one centimeter!

Compared to the average distance of almost 40,000,000,000 centimeters, we're talking about a sensitivity of order 25 parts per trillion.

That means if you remove a "mere" two billion tons of mass from the Moon, you'll have a detectable effect on the Moon's orbit via precise laser ranging measurements.

So if mining were to remove enough material to change the

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    $\begingroup$ well, the goal is for the moon to either fly away or collide with the Earth -- a small but measurable change is not nearly as exciting. as mentioned, my idea is that perhaps there is a tipping point at which we can destabilize Luna economically. 2 billion tons of course a lot but not something the world does not deal in, like co2 emissions, waste plastic, etc. in fact co2 emissions dwarf 2 billion tons. $\endgroup$
    – releseabe
    Jan 13 at 0:51
  • $\begingroup$ @releseabe Yes I see what you mean. I wrote a "yes" answer to the title to offset the "no" answers, but if "the goal is for the moon to either fly away or collide with the Earth" then I think it is not possible. What you need is propulsion change the angular momentum of whatever mass there is in orbit, not changing the mass. So for example the premise of the 1977 TV show Space 1999 involved some kind of propulsive event associated with a nuclear waste dump (I never understood how) that boosted the Moon out of orbit and into deep space. $\endgroup$
    – uhoh
    Jan 13 at 22:14
  • $\begingroup$ @releseabe to do that, you would need to keep pushing on the Moon in the same direction it's moving. The confusing thing is that this would raise its orbit but slow it down even though you'd be adding energy (higher orbits move slower). If you want a collision, then you have to push on the Moon in the opposite direction that it's moving, which would lower its orbit (and energy) but result in faster orbiting. Just for fun :-) youtu.be/Y6BXaGEuqxo?t=2458 $\endgroup$
    – uhoh
    Jan 13 at 22:24
  • $\begingroup$ No, I want to change its mass by knock chunks off of it. $\endgroup$
    – releseabe
    Jan 13 at 22:56
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Not really, We would have to mine AT LEAST 1% of Luna's mass for the reduction to have any effect on its orbit of Earth.It would take millenia to mine that much material. Remember,though the mass of our moon is 1.2% that of Earth, it's still 7.342x10000000000000000000000 kilograms!

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    Jan 12 at 7:47

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