The Cislunar Economy: What Would Have to Be True

The development of human activity beyond low Earth orbit has historically operated on a model of absolute dependence. Every kilogram of oxygen, propellant, and food consumed by an astronaut is typically launched from the surface of the Earth, fighting a gravitational gradient that necessitates enormous energy expenditure for modest returns. To move a payload from the surface of our planet to the lunar surface requires a vehicle where roughly 90 per cent of the mass at liftoff is fuel. This ratio is the fundamental constraint of chemical rocketry. It ensures that any mission remains a discrete, high-cost event rather than a sustained economic process.

For a cislunar economy to transition from a government-funded demonstration to a self-sustaining system, the cost of transit must fall below the value of the activity being performed. Current projections suggest this cannot be achieved solely through the reuse of launch vehicles. Even with rapidly plummeting costs to reach orbit, the physics of moving between deep-space destinations remains prohibitively expensive if every drop of propellant must be dragged out of Earth's gravity well. The alternative is to find the mass in space.

The concept of in-situ resource utilisation focuses on the Moon as a source of propellant. If water can be extracted from the lunar surface and processed into liquid hydrogen and liquid oxygen, the Moon becomes a filling station for the solar system. This would fundamentally alter the delta-v budget of deep-space missions. In this scenario, Earth-launched rockets would carry only high-value payloads and the fuel required to reach a staging point, where they would dock with tankers supplied by lunar mines.

Whether this transition is physically and economically viable depends on several technical certainties that have not yet been demonstrated at scale. It requires the presence of accessible volatiles, the engineering capability to extract them in a vacuum, and a logistical network to move products between orbital planes. Without these components, the cislunar economy remains a collection of aspirational slides rather than a functional market.

Gravity wells and the mathematics of propellant

The difficulty of space travel is best understood through the concept of delta-v, or the change in velocity required to move from one orbit or surface to another. Because gravity follows an inverse-square law, the energy required to escape Earth is significantly higher than that required to navigate between points in deep space. To reach the Moon from Earth, a spacecraft must achieve a velocity of approximately 11 kilometres per second. Because the Moon is much smaller, escaping its gravity requires only 2.4 kilometres per second.

This disparity creates a gravitational imbalance that favors lunar resources. In energetic terms, the Moon sits at the top of a hill while the Earth sits at the bottom of a deep pit. It is significantly cheaper to move a tonne of material from the lunar surface to a high Earth orbit than it is to move that same tonne from the surface of the Earth to the same destination. This holds true even though the lunar infrastructure does not yet exist; the physics of the potential energy difference is immutable.

The Tsiolkovsky rocket equation dictates that the mass of a rocket grows exponentially with the delta-v required. To add a small amount of velocity, one must add fuel, which itself has mass and requires more fuel to move. This "rocket equation trap" is the primary barrier to deep-space exploration. By sourcing propellant from the Moon, missions can bypass the most energy-intensive segment of the journey. A spacecraft could launch from Earth nearly empty of fuel, docking at a propellant depot in orbit to fill its tanks before proceeding to Mars or the outer planets.

The energy required to lift a kilogram of water from the Moon to a high orbit is less than five per cent of the energy required to lift it from Earth.

This mathematical reality creates a theoretical price floor for lunar-derived propellant. If the cost of mining and refining water on the Moon, plus the cost of transporting it to a depot, is lower than the cost of launching an equivalent mass from Earth, a market emerges. If it is higher, the lunar operation remains a subsidy or a scientific curiosity.

The chemistry of lunar volatiles

The primary target for lunar mining is water ice. Until the late 20th century, the Moon was largely considered a bone-dry environment, baked by billions of years of solar radiation. However, data from several orbital missions, including India’s Chandrayaan-1 and NASA’s Lunar Reconnaissance Orbiter, confirmed the presence of hydrogen signatures in permanently shadowed regions near the lunar poles. These are craters where the rim blocks all sunlight, creating cold traps with temperatures that have remained below 100 Kelvin for billions of years.

The chemistry of these deposits is not yet fully characterised. It is likely that the "ice" is not a clean, terrestrial sheet of frozen water, but rather a complex mixture of water molecules, hydroxyl radicals, and other volatiles such as carbon dioxide, ammonia, and methane. These substances are thought to have been delivered by cometary impacts or formed through the interaction of solar wind protons with oxygen-rich minerals in the lunar soil, known as regolith.

To create rocket propellant, the water must be purified and then split into its constituent parts via electrolysis. Passing an electric current through water breaks the molecular bonds, yielding hydrogen and oxygen gases. These must then be cryogenically cooled into liquid form. Hydrogen is an exceptionally efficient fuel but is difficult to store because its small molecules leak through many materials and it must be kept at temperatures near absolute zero. Oxygen is easier to handle and makes up the majority of the mass in a typical bi-propellant system.

There is significant uncertainty regarding the concentration and depth of these ice deposits. If the water is present as a thin frost on the surface of dust grains, extraction will be energy-intensive. If it exists as discrete chunks of pure ice buried a metre underground, the engineering challenge changes entirely. Current consensus suggests that the ice is likely heterogeneously distributed, meaning a lunar mining operation will require sophisticated prospecting before it can begin large-scale production.

Extraction mechanisms for polar water ice

Mining in the permanently shadowed regions of the Moon presents an engineering paradox: the very lack of sunlight that preserves the ice also denies the primary source of power for extraction. Any machinery operating in these craters must either carry massive batteries, be powered by long cables from the sunlit rims, or use mirrors to reflect sunlight into the darkness.

Two primary methods for extraction are currently under investigation. The first is mechanical excavation, where robotic rovers dig up the icy regolith and transport it to a processing plant. This plant would heat the soil in a sealed chamber, causing the ice to sublimate into gas, which is then captured and condensed. The challenge with this approach is the abrasive nature of lunar dust. Regolith is composed of sharp, glass-like shards that have not been weathered by wind or water. This material causes rapid wear on mechanical seals, joints, and cutting edges.

The second method is in-situ thermal extraction. In this model, a tent or dome is placed over the lunar surface, and heat is applied directly to the ground—either through microwaves or reflected sunlight. The water ice sublimates directly from the soil and is captured on a cold plate within the dome. This avoids the need to move large quantities of abrasive regolith, but it requires precise control of the heating element to ensure the gas does not escape into the vacuum of space.

Confidence in these technologies is currently low, as they have only been tested in vacuum chambers on Earth using lunar "simulants." Real lunar regolith may behave differently, particularly regarding its thermal conductivity in a vacuum. Furthermore, the extreme cold of the lunar poles causes standard lubricants to freeze and makes metals brittle. Any extraction mechanism must be capable of operating for years with minimal human intervention, as the cost of sending repair crews would negate any economic gain from the propellant produced.

Logistical nodes in Lagrange points

Once propellant is produced on the lunar surface, it must be moved to where it is needed. In a cislunar economy, the most important locations are not on the surface of planets or moons, but at Lagrange points. These are positions in space where the gravitational pull of two large masses, such as the Earth and the Moon, precisely cancels out the centripetal force required for a small object to move with them.

The Earth-Moon L1 point, located between the two bodies, and the L2 point, located behind the Moon, are ideal sites for fuel depots. A station at L1 is a "gateway" that allows easy access to both the lunar surface and various Earth orbits. Because these points are gravitationally balanced, a station can maintain its position with very little fuel. It becomes a logistical hub—a place where lunar tankers can drop off propellant and where Earth-launched spacecraft can arrive to refuel before heading to more distant destinations.

• Tankers would use a shuttle-like profile to lift liquid oxygen and hydrogen from the Moon to L1.
• Deep-space vessels would rendezvous at L1 to take on fuel, avoiding the need to land on the Moon themselves.
• Satellites in geostationary orbit could be serviced or moved by tugs based at these nodes, extending their operational lifespans.

The transition from a subsidy to a market occurs when multiple entities begin using these nodes. If a single agency owns the mine, the tanker, and the destination, it is a closed-loop mission. A true market requires a diversity of actors: one company mining the ice, another providing the orbital storage, and a third buying the fuel to move a commercial satellite. For this to happen, there must be a standardisation of docking interfaces and fuel transfer protocols. We are currently in the pre-competitive phase, where the primary challenge is not competition, but the establishment of the basic infrastructure required for any commerce to exist.

The delta-v advantage of lunar manufacturing

The economic case for lunar industry rests on the gravity well. To move a kilogram of mass from the surface of the Earth to a low orbit requires a change in velocity, or delta-v, of roughly 9.4 kilometres per second. To move that same kilogram from the Moon’s surface to an equivalent lunar orbit requires approximately 2.4 kilometres per second. Because the relationship between fuel mass and delta-v is exponential, as described by the Tsiolkovsky rocket equation, the energy saved by sourcing materials from the Moon rather than the Earth is significant. A craft departing from the Moon can reach high Earth orbits or deep space destinations with a fraction of the propellant required by a craft launching from the Florida coast.

Propellant is the most logical first export because it constitutes the majority of a spacecraft's mass. Most current designs for lunar water extraction focus on the permanently shadowed regions of the lunar poles, where water ice is thought to be trapped in the soil, or regolith. By applying thermal energy to the regolith, the ice can be sublimated and captured. Once purified, the water is subjected to electrolysis, splitting the molecules into hydrogen and oxygen. These are then cryogenically cooled into liquid form. When burned together, they provide a high specific impulse, making them an efficient chemical propellant.

Beyond fuel, the manufacturing of structural components from lunar regolith offers a way to bypass the size constraints of terrestrial rocket fairings. On Earth, every beam, solar panel, and hull segment must be designed to survive the high-frequency vibrations of launch and fit within a cylinder five to seven metres wide. On the Moon, vacuum induction melting or sintering could produce large-scale trusses and shielding from raw lunar soil. Aluminium, iron, and titanium are relatively abundant in the lunar highlands and maria. If these metals can be refined in situ, the mass penalty of lifting heavy shielding or large structures out of Earth’s gravity is removed. The primary advantage here is not that lunar materials are better, but that they are already at the top of the gravity well.

Transitioning from terrestrial resupply to local sourcing

The shift from Earth-dependence to local sourcing follows a predictable sequence of technical milestones. Initially, every gram of life support, hardware, and propellant must come from Earth. This is the current state of lunar exploration, where the cost per kilogram remains a prohibitive barrier to permanent occupation. The first phase of transition involves reducing the mass of consumables. Oxygen extraction from regolith is technically simpler than water extraction in some respects, as roughly 40 per cent of the lunar soil by weight consists of oxygen bound in silicate minerals. Demonstrations have shown that heating regolith in the presence of hydrogen or through molten salt electrolysis can liberate this oxygen, providing breathing gas for habitats and oxidiser for rockets.

The second phase is the substitution of bulk materials. Shipping lead or water from Earth to protect astronauts from solar particle events and cosmic rays is inefficient. Instead, early habitats will likely be buried under several metres of unprocessed regolith. This provides thermal stability and radiation protection using existing mass. As robotic capabilities improve, this evolves into the construction of landing pads. Plumes from descending rockets can sandblast equipment and nearby modules with high-velocity dust. By sintering the regolith into solid bricks or glass-like surfaces, a colony reduces the maintenance burden caused by abrasive lunar dust.

The final phase, and the most difficult to achieve, is the local production of precision components. While a beam can be cast from crude aluminium, a microprocessor or a high-pressure seal requires a sophisticated industrial ecosystem that does not yet exist outside of Earth. The transition will therefore be lopsided. For the foreseeable future, high-complexity, low-mass items will be imported from Earth, while low-complexity, high-mass items will be produced locally. The economic viability of the cislunar system depends on the ratio of these two categories. If the cost of maintaining the local manufacturing equipment exceeds the savings from reduced launch costs, the system remains a net drain on terrestrial resources.

Structural differences between subsidies and markets

Current lunar missions are almost entirely subsidised by national governments. A subsidy is a transfer of wealth intended to achieve a strategic, scientific, or political objective without the immediate requirement for a return on investment. In this environment, the "customer" is the government, and the "product" is prestige or data. While these programmes fund the initial development of technology, they do not constitute a market. A market requires the presence of price signals, competition, and, eventually, a profit motive that operates independently of legislative whim.

For a cislunar market to form, there must be a decoupling of the provider and the user. If an agency builds its own rover to search for its own water to fuel its own lander, the internal costs are opaque. A market begins when one entity offers a service, such as power or data relay, at a fixed price to any paying customer. This creates an incentive for the provider to lower costs through efficiency, rather than simply fulfilling a cost-plus contract. It also allows new entrants to participate without needing to build an entire end-to-end transport system.

The existence of a market is signaled by the moment a private company chooses to buy a service from a peer rather than building the capability in-house.

The risk in the current model is a "monopsony," where the government is the only buyer. If the government decides to cancel a programme, the entire economic structure collapses. A resilient cislunar economy requires diverse demand. This might come from satellite operators needing their assets repositioned, private research stations, or tourism. Until the customer base diversifies beyond the taxpayer, the cislunar economy is a set of government projects rather than a self-sustaining commercial zone.

Unresolved technical barriers to long-term habitation

Despite the promise of lunar resources, several physical and biological hurdles remain poorly understood. The most significant is the effect of lunar gravity on the human body over long durations. We have extensive data on the effects of microgravity from the International Space Station and full gravity on Earth, but the effects of one-sixth gravity are unknown. It is possible that the lunar environment is sufficient to prevent the bone density loss and muscular atrophy seen in orbit, but it is equally possible that it is not. If long-term residence leads to irreversible health declines, the cislunar economy will have to rely almost entirely on robotics, which changes the cost-benefit analysis of local manufacturing.

The second barrier is the nature of lunar dust. Unlike terrestrial sand or dust, which is weathered by wind and water, lunar regolith is composed of sharp, jagged shards created by billions of years of micrometeoroid impacts. It is chemically reactive and highly abrasive. During the Apollo missions, dust clogged seals, scratched helmet visors, and caused respiratory irritation. Managing this dust in a permanent facility, where it will inevitably be tracked into living quarters, requires filtration and mitigation technologies that have not been tested at scale.

Power generation also remains a significant challenge, particularly during the lunar night, which lasts roughly 14 Earth days. Solar power is the most accessible energy source, but storing enough energy to survive two weeks of darkness requires massive battery arrays or fuel cells that are currently too heavy to be practical. The alternative is nuclear power, specifically small modular reactors. While technically feasible, the political and regulatory hurdles of launching and operating nuclear reactors in space are substantial. Without a consistent, high-output power source, industrial processes like electrolysis and metal refining cannot operate continuously.

The threshold for a self-sustaining orbital economy

An economy becomes self-sustaining when the wealth generated within the system exceeds the cost of the inputs required from Earth. This threshold is rarely reached in a single step. It is more likely to emerge as a series of narrowing deficits. The first indicator of reaching this threshold will be the price of propellant in high Earth orbit. If the cost of lunar-derived fuel delivered to a geostationary transfer orbit is lower than the cost of fuel launched from Earth, a structural shift will occur. Every commercial satellite operator would, in theory, switch to the cheaper source, creating a permanent demand signal.

A second indicator is the "break-even" point for hardware recycling. Currently, satellites are discarded at the end of their lives. A self-sustaining economy would treat these as high-value caches of refined metals and components. The ability to repair, refuel, and upgrade assets in situ would extend the life of orbital infrastructure indefinitely. This requires a level of robotic dexterity and standardisation that is currently in the experimental stage.

The ultimate threshold is the point at which the cislunar system can produce the means of its own expansion. This would involve a facility on the Moon capable of producing solar cells and simple structural parts for more solar cells and more factories. At this stage, the growth of the infrastructure is no longer limited by the number of rockets launched from Earth, but by the speed of local production. We are several decades from such a capability.

What is established is the physics: the delta-v advantage of the Moon is a mathematical certainty. The presence of water ice at the poles is supported by multiple orbital observations and impact data, though its exact concentration and accessibility remain contested. What would change the picture most significantly is a discovery that water ice is either too deeply buried or too chemically complex to be easily refined. Conversely, a breakthrough in automated mining or a significant reduction in the cost of heavy-lift launches from Earth could either accelerate or render redundant the need for lunar manufacturing. The cislunar economy is currently a plausible engineering goal, but its transition to a functioning market depends on overcoming biological and technical uncertainties that cannot be solved by investment alone.