Excavate, Sort, Extract, and Separate: Interlune Core Intellectual Property

Interlune aims to be the first company to commercialize natural resources from space, starting with Helium-3 from the Moon. In time, we will harvest other resources such as industrial metals, rare Earth elements, and rocket propellants to support a long-term presence on the Moon and a robust in-space economy. 

A key aspect of the Interlune business model is the ability to focus on technology for harvesting space resources. Our team is developing the technology to do this on the Moon at scale. 

The Interlune Harvesting System

The Interlune harvesting system involves four key processes - excavating, sorting, extracting, and separating - with proprietary technology at every step. Importantly, the Interlune Harvester deposits processed regolith back onto the Moon's surface, leaving the surface looking like a tilled field. It is designed to be 100% robotic and to operate autonomously with remote human monitoring and intervention as needed.

The Interlune Harvester will use vision sensors and ground-penetrating radar to determine the optimum harvesting route plan. A robotic arm will move surface rocks that are too large to process. The harvester will alter course or pause excavation to get around obstacles that are too large to move or beneath the surface.

The Moon presents us with a challenging environment. Here are some of the critical considerations in developing technology for use on the Moon.

• Size and Mass: Current prices for delivery of payloads to the Moon on small commercial landers are on the order of $1 million per kilogram. This will improve substantially with the large lunar landers such as Starship (SpaceX) and Blue Moon (Blue Origin). Still, size and mass will always be critical considerations in designing our harvesting system. 
• Power Infrastructure: Large-scale harvesting operations on the Moon will require a lot of power, which requires a power infrastructure - a lunar power grid. The most straightforward way to obtain power in space is with solar panels, but this doesn’t help during lunar nights, which are more than 14 consecutive days long about 50% of the time. We must operate as efficiently as possible, but we must also devise methods of power storage or generation when the Sun isn’t visible.
• Gravity: Lunar gravity is about six times lower than on Earth, presenting unique challenges (as well as opportunities) in designing excavation or regolith conveyance systems. 
• Extreme Temperatures: Near the Moon's equator, temperatures range from -208 degrees Fahrenheit at night to 250 degrees Fahrenheit during the day. At the poles, NASA has measured temperatures as low as -410 degrees Fahrenheit.
• Radiation: Radiation on the surface of the Moon is much higher than in low Earth orbit, making it necessary to shield electronics during missions.
• Dust: The rock debris that covers the surface of the Moon, called regolith, is composed primarily of very fine abrasive dust. This dust tends to stick on and get into everything, including solar panels, radiators, seals, and bearings.

By the early 2030s, Interlune plans to have a fully operational plant harvesting Helium-3 from the Moon and selling it to customers on Earth. These challenging environments and risks lead us to plan at least two demonstration missions to test out key technologies before deploying the full plant. The first is a Resource Development Mission planned for 2027 to validate concentrations of Helium-3 at the future harvesting site and test out extraction on a small scale. Next, Interlune plans a Pilot Plant on the Moon in 2029 to prove out every step, including getting lunar-derived Helium-3 into the hands of our customers.

Many of the challenges of operating on the Moon are also shared by other entities, such as NASA’s Artemis program. Interlune can, therefore, leverage existing and emerging technologies, including launch and landing, sample return, power, communications, and surface transportation. This allows Interlune to focus almost solely on its harvesting system. The harvesting system performs four major sequential processes: Excavation, Sorting, Extraction, and Separation.

‍

STEP 1: EXCAVATE

Excavation involves digging up large volumes of lunar regolith, up to 100 tons per hour per Harvester. Excavating this volume is easy on Earth, where there are few practical restrictions on equipment size and power consumption. But for Interlune, every gram of equipment weight matters, and the power supply will be much more limited. Consequently, the Interlune Harvester operates continuously, avoiding the inefficiencies of multiple stops and starts. It excavates the regolith, processes it, and then returns it to the surface in a nonstop continuous motion. Interlune is developing a novel, proprietary method of performing this high-rate continuous excavation with extremely low power and tractive force. 

Today, we’re building sub-scale models of excavator concepts and testing them with regolith simulants to measure power consumption and performance. We’ll build full-scale prototypes later this year. 

STEP 2: SORT

Size sorting of soils is a critical industrial process on Earth, and will be equally critical to supporting resource extraction and construction on the Moon. Interlune’s sorting technology uses centrifugal motion to rapidly spin and sort through large volumes of regolith using a small number of moving parts.

Compared to existing devices on Earth, Interlune sorting technology handles a much higher volume of material and is more mass-efficient and reliable due to fewer mechanisms. Moreover, we can test and iterate extensively on Earth without simulating lunar gravity because the primary sorting mechanism is with centrifugal force rather than gravity.

While Interlune is self-funding much of its research and development, it has also received a National Science Foundation (NSF) Small Business Innovation Research (SBIR) Phase I award to operationalize its sorting technology. The NSF SBIR Phase I award is funding prototype testing on Earth under simulated lunar conditions, and future phases may support full-scale development and demonstration on the Moon.

STEP 3: EXTRACT

After the regolith is excavated and sorted (rejecting the coarser particles back to the surface), it enters the Extraction process. Extraction refers to releasing the mixture of gases from the lunar regolith. The gas mixture we will extract will include solar-wind deposited volatiles such as Helium-4, Hydrogen, Helium-3, and other trace gases. 

NASA’s Space Technology Mission Directorate (STMD) framework outlines the need for in-situ resource utilization (ISRU) for construction, advanced manufacturing, and production of fluids and gases for propellant and life support. However, the state-of-the-art process of extracting resources from lunar regolith requires large amounts of energy in the form of heat, which, as previously mentioned, is scarce on the Moon. 

Interlune has developed a low-power, highly efficient way of releasing solar wind volatiles from regolith. Our method, focused on getting the solar-wind volatiles containing the Helium-3, requires ten times less power than heat-based methods of ISRU. Last February, we tested a prototype device in simulated lunar gravity on a parabolic flight operated by Zero Gravity Corporation. 

Interlune will use funds from a NASA TechFlights grant to support further testing of this extraction technology. The testing will include a simulated lunar gravity environment and incorporate regolith simulants processed in a vacuum. We will analyze trade-offs in size, weight, and power required for different performance levels using parabolic flights. Interlune will use the results to plan for scaling its technology to handle multiple tons of regolith.

STEP 4: SEPARATE

The process of Excavation, Sorting, and Extraction returns nearly all the regolith back to the surface. It retains a small amount of the original material in the form of a gas in the Harvester. But even this gas contains only a small percentage of Helium-3. To make it profitable to return to Earth, we must enrich the concentration of Helium-3 by separating it from other molecules. This step requires very low temperatures. We can do this with conventional cryogenic distillation processes, but we’re also looking at new technologies developed for creating green hydrogen, which could provide the low temperatures required for Helium-3 separation, and which may be more energy efficient than conventional cryocoolers. 

We are also evaluating the use of these new technologies for a terrestrial plant that separates Helium-3 from regular Helium derived from Earth-based sources. While this would not produce the Helium-3 in the quantities our customers need, it’s a good first step to shore up the supply chain and demonstrate our capabilities before going to the Moon. 

Even if this weren’t a stepping stone for Interlune, increasing the Helium-3 supply on Earth without producing more Tritium is highly worthwhile. 

Resource Development Mission

Interlune’s first dedicated lunar mission will focus on validating the concentration of Helium-3 and other solar wind volatiles at a potential future harvesting site, evaluating the site for operations, and demonstrating Interlune’s proprietary extraction technology in the lunar environment.

The Interlune payloads will fly on a commercial robotic lander developed for NASA’s Commercial Lunar Payload Services (CLPS) program. These payloads will generate a wealth of scientific data, including surface and subsurface geotechnical characterization, regolith composition, and solar wind volatile data.

Interlune is currently designing this mission, evaluating commercial landers, and entertaining research collaborations.

Pilot Plant

The Pilot Plant will demonstrate nearly every aspect of our operating plant’s operation by returning meaningful quantities of Helium-3 to our customers for a fraction of the launch mass and cost. Lessons learned will be incorporated into plans before deploying the full system to the Moon in the early 2030s.

We will gather data at all phases to validate analytical models of performance, induced environments, and natural environments. Some of our pilot plant activities include:

• Qualifying hardware and software
• Testing production and assembly
• Demonstrating integration with launch and landing systems
• Demonstrating setup on the lunar surface
• Refining optimal harvesting parameters, including excavator speed and angle
• Training and practicing remote operations equipment
• Testing power, communications, and operations during both lunar day and night cycles
• Demonstrating multiple returns of Helium-3 to Earth
• Testing the quality of the Helium-3 mixture once returned to Earth
• Selling a subset of the gas returned to a customer

Four Steps. World Changing Implications

We’ve given you a small peek into our plans to harvest natural resources from space. There are lots of details on lunar science, engineering, financial models, customer conversations, and a myriad of other details we’re not able to share yet. There are also other innovators, such as launch and landing providers, on which Interlune will rely, allowing it to focus on harvesting technology. But we hope this summary helps build excitement and conviction around the Interlune mission to lead the world in sustainable, responsible harvesting of natural resources from space to benefit humanity.

‍