title: "Lunar Mechanical Imbalance: Possible Scenarios and Their Impact on Humanity's Future" date: "2026-06-05" category: "space" author: "Zhigeng"

Lunar Mechanical Imbalance: Possible Scenarios and Their Impact on Humanity's Future

When humanity begins developing the Moon, what will happen to the Earth-Moon system?

Human enthusiasm for lunar exploration is growing ever more intense. Around 2030, the U.S. Artemis program, China's crewed lunar landing, and lunar base projects from multiple nations are all advancing rapidly. As lunar planning and activities increase, a question that must eventually be confronted is surfacing:

If humanity mines lunar resources on a large scale and builds structures on the Moon, could this disrupt the Moon's mechanical equilibrium?

This is not science fiction—it is a question that deserves serious investigation at the intersection of celestial mechanics and engineering.

I. First, Understanding the Moon's "Mechanical Equilibrium"

The Moon's current mechanical state is the result of billions of years of evolution, primarily constituted by three levels of equilibrium:

The first level: orbital equilibrium of the Earth-Moon system

The Moon orbits the Earth in an elliptical path. The gravitational attraction between the Earth and Moon is essentially balanced by the centrifugal force of the Moon's orbital motion. This equilibrium determines the Moon's orbital radius (approximately 380,000 km) and its orbital period (about 27.3 days).

The second level: Earth's tidal locking equilibrium

The Moon always presents the same face toward the Earth—this is called "tidal locking." Over billions of years, Earth's gravitational gradient (tidal force) has "stretched" the Moon into a slightly ellipsoidal solid body—with its long axis pointing toward Earth. This shape is precisely matched to its rotation period, forming a stable locked state.

The third level: equilibrium of mass distribution

The Moon's center of mass does not perfectly coincide with its geometric center (the Moon's mass distribution is non-uniform). But this "eccentricity" has been "accepted" by the Earth-Moon system for billions of years. The Moon is currently in a state of dynamic equilibrium.

So the question is: if humanity mines lunar resources on a large scale, which equilibria might be disrupted?

II. Several Possible Scenarios of Lunar Mechanical Imbalance

Scenario One: Large-Scale Mass Transfer—Center-of-Mass Shift

This is the most direct risk.

The Moon's surface mineral deposits (especially helium-3, rare earth metals, silicon, aluminum, iron, magnesium, etc.) are unevenly distributed. If humanity concentrates mining in one region and transports large masses back to Earth or uses them for space construction, or builds bases at different sites on the Moon, this could cause a measurable shift in the Moon's center of mass.

What are the consequences?

After the Moon's center of mass shifts, its rotation axis would undergo small changes. Although the Moon's rotation is locked to Earth, such mass redistribution could trigger subtle perturbations in libration—the Moon would begin to "wobble" more noticeably.

Further consequences: a shift in the center of mass would alter the gravitational field that the Moon exerts on Earth, in turn affecting tidal patterns on Earth. Global tidal changes—not merely sea level rising by a few millimeters, but measurable changes in tidal amplitudes at major ports.

What is the threshold?

A rough estimate: if one hundred-thousandth of the Moon's mass (about 7.35 × 10^17 kg, equivalent to a large mountain range) were transferred from one hemisphere to the other, it would produce an observable shift in the center of mass. This number sounds huge—equivalent to moving the entire Himalayas from one side of the Moon to the other—but considering the long-term scale of lunar mining, it is not entirely out of reach.

Scenario Two: Overall Mass Reduction—Lunar Orbital Change

This logic is more straightforward: if large amounts of material are transported away from the Moon—whether to Mars or back to Earth—the Moon's total mass will decrease.

According to the law of universal gravitation, the gravitational force between Earth and Moon is proportional to their respective masses. Less lunar mass → weaker Earth-Moon gravitational force → larger lunar orbital radius → longer orbital period.

Consequences: the Earth-Moon distance increases, tides weaken, and the slowing of Earth's rotation is affected.

Currently, the Moon is receding from Earth at a rate of 3.8 cm per year (a natural phenomenon driven by tidal effects). If humanity additionally removes material from the Moon, this recession rate will accelerate further.

What is the threshold?

The good news is—this threshold is very high. The Moon's mass is approximately 7.35 × 10^22 kg. For artificial extraction to exceed the natural tidal recession rate (3.8 cm/year), humanity would need to remove roughly 10^15 kg of material from the Moon per year—equivalent to relocating an entire Mount Everest every year.

In the foreseeable future, humanity is unlikely to reach this scale of extraction. So the risk of overall mass reduction can be ignored for the next hundred years.

In truth, a hundred years is not far off. Although the threshold is high, if this factor is completely ignored, it will sooner or later become a case of "those who fail to look ahead will soon find trouble close at hand."

Scenario Three: Tidal Locking Disturbed—The Moon "Flips Over"

This is the most subtle, and most imagination-stirring, possibility.

The Moon's tidal locking depends on its non-uniform mass distribution—the Moon's near side is "heavier" (more mass-concentrated) than its far side, and this asymmetry allows Earth's gravity to "pin" the Moon in its locked state.

If humanity mines the Moon on a large scale, it could alter this asymmetric equilibrium.

An extreme hypothesis: if enough mass is removed from the Moon (mined and transported back to Earth or to Mars), the Moon's mass distribution could change—and the existing tidal locking could strengthen, weaken, or loosen.

Whether this large-scale removal occurs on the far side, near side, or lateral regions, the resulting unlocking patterns would correspond respectively to strengthening, weakening, or lateral rotation. If mass is instead relocated across the Moon's surface on a large scale rather than removed, the changes would be even more complex.

The most dramatic scenario: the Moon begins to slowly rotate, no longer presenting the same face to Earth.

What would happen then?

This is the greatest uncertainty. If the Moon begins to rotate slowly, tidal patterns on Earth would undergo gradual changes. In the short term, not much—but in the long term, if humanity plans to establish permanent bases on the Moon, a lunar "flip" would mean the original base location is no longer on the near side, and communication and illumination conditions would all change.

What is the threshold?

This is harder to estimate precisely than the center-of-mass shift, but a basic judgment is: the extraction volume would need to reach between one ten-thousandth and one thousandth of the near-side mass. Higher than the first threshold, but far lower than the second.

Scenario Four: Internal Structural Disturbance—Triggering Moonquakes

The Moon is not completely solid. It has a small core (partially molten), surrounded by a mantle and crust.

Large-scale mining, especially deep crust mining, could alter the internal stress distribution of the Moon and trigger "moonquakes."

Deep moonquakes were recorded during the Apollo missions, proving that the Moon still has some residual tectonic activity. If human mining activities alter the stress field, they could trigger more frequent moonquakes.

Consequences: For lunar bases, moonquakes themselves are a risk. A more indirect impact is that severe moonquakes could alter the Moon's surface mass distribution, triggering the center-of-mass shift discussed earlier.

III. How Important Is Lunar Mechanical Stability to Humanity?

Why is the Moon's mechanical stability so important?

Because many matters on the Moon are connected to Earth.

Tides—the rhythm regulator of life on Earth

The Moon's gravity is the primary driver of Earth's tides (the Sun contributes the remaining roughly one-third). The impact of tides on life on Earth is far greater than most people imagine:

Intertidal zone ecosystems: completely dependent on tidal rhythms—submerged at high tide, exposed to air at low tide. Hundreds of thousands of kilometers of coastline ecosystems on Earth depend on tides for survival.
Ocean circulation: influenced by tidal mixing. If tidal patterns change significantly, ocean currents could be altered, in turn affecting the global climate.
Deceleration of Earth's rotation: primarily caused by lunar tidal braking. Without the Moon, Earth's rotation might be much faster than today—a day could be only 8 hours.

If the Moon's mechanical state changes—even by a center-of-mass shift of just a few centimeters—tidal patterns would change accordingly. Not just a matter of sea level rising a few millimeters, but the timing, amplitude, and even the direction of tidal wave propagation would change.

For coastal cities, ports, fisheries, and renewable energy projects that depend on tidal power, none of this is good news.

The long-term evolution of the Earth-Moon system

The long-term stability of Earth's climate partly depends on the Moon's gravity—it stabilizes the tilt angle of Earth's rotation axis (about 23.5 degrees), which is the origin of the four seasons. Without the Moon, Earth's rotation axis could swing wildly between 10 and 50 degrees (as happens on Mars), causing the climate to oscillate between extreme ice ages and extreme warm periods.

In this sense, the Moon is not just an astronomical satellite—it is Earth's "climate voltage regulator." Its mechanical stability is one of the bottom lines for the long-term survival of all life on Earth.

The Moon is one of Earth's protective shields

The Moon's presence helps shield Earth from and reduce the risk of asteroid impacts. Many of the craters on the Moon are scars left by such shielding. A smaller or more distant Moon would reduce this shield's protective area.

The needs of lunar bases themselves

If humanity plans to establish permanent bases on the Moon, lunar mechanical stability is not just an Earth problem—it is a problem for the lunar bases themselves.

Lunar base site selection must consider:

Moonquake risk: high-frequency moonquake zones are unsuitable for bases
Illumination conditions: base locations need long-term stable illumination windows (some polar base designs are planned for "eternal daylight" zones, relying on the stability of the Moon's rotation axis)
Communication conditions: if the Moon undergoes significant libration, the base's communication windows with Earth would change and become unstable

What humanity does to the Moon will ultimately affect human survival conditions on Earth.

Mining does not equal mass removal

A celestial mechanics insight—perhaps the biggest concern about "disrupting mechanical equilibrium through lunar resource extraction" is not about removing mass but about redistributing mass.

Because while some portion of minerals mined from the Moon's surface may be transported to Mars, it is unlikely they would be shipped back to Earth (the cost is too high, and Earth must primarily rely on its own resources). The more massive scenario is likely: in-situ smelting and processing on the Moon, for use in lunar base construction.

This means: large-scale redistribution of mass on the Moon's surface—dug from Crater A, piled at Factory B, used for Base C.

This "in-situ redistribution" could pose a greater risk of center-of-mass shift than "removal."

It's somewhat analogous to a phenomenon in business competition: Anthropic takes market share from OpenAI not because OpenAI's customers evaporate, but because Anthropic's own products attract customers to switch voluntarily.

Returning to the core question—how to grasp the threshold? Here's an interesting analogy: the "safety alignment" problem in AI.

It's like Anthropic's Mythos cybersecurity model—it can discover over 20 critical vulnerabilities in a matter of weeks. There's a consensus in AI safety circles: safety does not come from after-the-fact patching, but from principles embedded during the training phase. The same applies to lunar mechanical protection—waiting until the center of mass has actually shifted to "fix" it would cost far more than establishing rules now.

IV. How to Develop Safely While Avoiding Crisis?

First, international legislation—laws before action. (This publication will address this topic in a dedicated essay; for now, it is omitted.)

Second, monitoring and regulation in accordance with law.

A three-tier collaborative, monitoring, and regulatory system could be considered:

Humanity is divided into different camps on Earth, but when faced with the harsh survival conditions of outer space, we become partners in jointly expanding the human living space—our fates are bound together. A spirit of collaboration should be established, along with agreed-upon principles and methods of cooperation.

Regulation is not about controlling each other—it is about controlling risk—and this is the most important part of cooperation. And monitoring is the prerequisite for regulation.

How to monitor?

Tier One: Monitoring (starting from the very first extraction). Establish gravitational monitoring stations on the Moon to continuously track changes in the Moon's center of mass, libration, and rotation parameters. Do not wait for problems to appear before remedying them—establish baseline data from the very beginning.
Tier Two: Quantity control (extraction scale relative to lunar mass) and utilization ratios for relocated material. Set a safety threshold—for example, one hundred-millionth of the Moon's mass (about 7.35 × 10^14 kg) as a "Phase One" upper limit. Within this range, mechanical impacts are essentially negligible. Beyond this amount, stricter assessment must be triggered.
Tier Three: Global coordination (unified global planning). The most critical point—the Moon does not belong to any single country; it belongs to all of humanity. Extraction plans must be collaborative and consensus-based, not "each country mining its own side" leading to unpredictable mechanical consequences.

Conclusion

Ranking the four scenarios by risk level:

The most practically significant and most urgent risk is the center-of-mass shift and induced moonquakes. These are medium-probability risks on the scale of decades to a century and should be incorporated into planning from the early stages of lunar development.

The scenarios that sound most frightening—such as "the Moon flipping over"—require extraction volumes so large that the probability of reaching them in the visible future is relatively low. Of course, such assessments are not necessarily safe. Just as on Earth, the vast majority of people never imagined that the activities of tiny humans could wreak havoc on the enormous Earth's oceans.

Protecting the Earth while developing the Moon follows the same logic as "don't put all your eggs in one basket." The premise is that this "other basket"—developed for the future safety of humanity's descendants—also needs long-term planning. Do not puncture the foundation of this much-anticipated basket from the very start, or it will truly be a case of drawing water with a bamboo basket—all in vain.

V. Is This Crying Wolf?

Some might say this is truly crying wolf: the Moon is so huge—how could it possibly happen?

Is that so?

When I was young and working as a journalist, I once interviewed a highly respected, renowned screenwriter. During the interview, as a kind of metaphor, he said: "The ocean has the power to purify itself." At the time, this struck my still-nascent soul with a force I have never forgotten. The impact was not just in his metaphorical sense, but in the contemplation of the real ocean's self-purifying capacity born of its vastness and depth—the assumption that it could never be polluted. In those days, our society was still in the early stages of industrialization; one could not imagine the ocean being polluted to the point of devastation.

Yet after China's reform and opening-up, barely two decades of genuine industrialization, our land, sky, water—and the global oceans under the great tide of globalization—what is their condition now?

No one can ever again imagine, ever again utter with conviction, the words: "The ocean has the power to purify itself."

The Moon, in total volume, is roughly comparable to the Earth's oceans—one theory of the Moon's origin even holds that the Moon was blasted out of the Earth by an asteroid, with the scar left behind being today's Pacific Ocean.

Now, with the momentum for lunar development and asteroid mining so conspicuous and developing so rapidly, if clear norms are not established in the early stages and adequate contingency plans are not made, the future of the Moon—and the future of humanity on Earth—could both be dimmed as a result.

This article is a forward-looking scientific projection. Some data are estimates; precise thresholds require further research to determine.