Space resources company Interlune announced on July 20 that it had separated 99% pure helium-3 from commercial Grade A helium. The experiment itself was conducted at the company's Seattle lab in early 2025, and this marks the first disclosure of the results. The company estimates that incorporating "Cold Capture" into helium processing facilities across the U.S. could increase annual supply by up to 2.5 kilograms. The core question to verify is not the 99% purity figure itself, but whether continuous recovery of this trace isotope can be achieved at industrial scale.
What 99% Purity Changes—and What It Doesn't
The change demonstrated by Cold Capture lies in the source material for helium-3. Current U.S. supply depends on a pathway where helium-3 generated from the radioactive decay of tritium used in nuclear weapons is recovered at the Savannah River Site in South Carolina. According to the U.S. Geological Survey (USGS), this was the only domestic facility producing helium-3 in 2025. Production volumes remain undisclosed to protect proprietary business information.
The Grade A helium that Interlune used as feedstock is a commercial product with total helium purity of 99.997% or higher, consisting almost entirely of helium-4. Within this, helium-3 exists at only about 200 parts per billion (ppb)—roughly 200 parts in a billion—which is concentrated to reach 99% of the product stream. Unlike the conventional pathway, this approach requires no new tritium production and can instead tap into helium streams already being recovered from natural gas.
However, 99% is not the same as recovery rate. The company has not disclosed what percentage of the helium-3 contained in the feedstock was actually extracted as product. The National Isotope Development Center (NIDC), under the U.S. Department of Energy, currently sells helium-3 with isotopic enrichment of 99.80% or higher. Cold Capture's achievement is not a purity record for an existing product, but rather a company claim of reaching practical-level enrichment from a different, more dilute source material.
Verification of the measurements is the next challenge. Interlune has not disclosed which institution conducted the analysis, nor has it provided the measurement method or margin of error. Sample volume, operating duration, and impurities in the product also remain unknown. While the single data point of 99% purity represents a proof-of-concept milestone, it cannot yet be judged whether a process meeting commercial product specifications has been established.
Exploiting Vapor Pressure Differences Near 4 K at Liquefaction Plants
Helium-3 and helium-4 are isotopes of the same element, making them difficult to separate through ordinary chemical reactions. Cold Capture exploits the difference in vapor pressure that arises at extremely low temperatures due to their mass difference. According to a plan listed in the U.S. Air Force's SBIR database, the process concentrates helium-3 into the vapor phase at approximately 4 K, near the boiling point. Repeated distillation creates a highly concentrated product stream from dilute feedstock.
The principle of cryogenic distillation has been known for some time. U.S. Patent US8683825B2, granted in 2014, describes a distillation column that recovers helium-3 from natural helium at 2.3–4.3 K. A 1995 experiment cited as prior art in that patent used a small packed column measuring 20 millimeters in diameter and 200 millimeters in height. With extremely dilute feedstock, enrichment can take months to years, meaning commercialization requires designs that minimize both processing time and cooling energy consumption.
Cold Capture's approach aims to share this cooling burden with existing liquefaction equipment. Interlune's 2025 U.S. Air Force SBIR Phase II contract, valued at $1,249,990, will define the physical, thermal, and operational interface conditions with liquefaction plants, and will prototype high-risk components such as cryogenic vessels, heat exchangers, and pumps. Between the company's lab-scale experiments and the plant-level integration targeted by the SBIR program, there remains the step of designing and operating pilot-scale facilities.
This sequence matters for interpreting the timing of the announcement. The achievement of 99% purity occurred in early 2025, before the SBIR award. The July 2026 announcement combines lab-scale product purity results with forward-looking expansion plans, rather than reporting results from plant-scale operations.
From 81 Billion Liters to a Maximum of 2.5 Kilograms: The Conditions Involved
The USGS estimates that 81 million cubic meters of Grade A and gaseous helium were sold in the United States in 2025. Converted to liters, this equals 81 billion liters. Domestically, five plants produce Grade A helium, while four additional plants refine crude helium from other sources into Grade A. Interlune aims to install its equipment across these multiple large-scale flows, recovering trace amounts of helium-3 gathered from various production sites.
The figure of up to 2.5 kilograms annually represents the company's estimate assuming widespread deployment across target facilities. Interlune states this could roughly triple current U.S. production, but since the USGS does not disclose current helium-3 production volumes, this multiplier cannot be independently verified using public statistics alone. Contracts with installation sites and operational start dates are also not included in this announcement.
The figures that will ultimately determine commercial viability are largely among those not yet disclosed: the recovery rate for capturing helium-3 from feedstock without loss, processing throughput per unit time, power consumption required to maintain equipment at approximately 4 K, and operational uptime including maintenance downtime. Whether the equipment can be added without disrupting production of helium-4—the primary commercial product—will also influence liquefaction plants' adoption decisions.
Interlune states it has secured legally binding purchase agreements worth approximately $500 million, primarily with quantum refrigerator manufacturers Maybell Quantum and Bluefors. The existence of prospective buyers is a prerequisite for capital investment. However, the company has not disclosed what portion of this contract value pertains specifically to Cold Capture supply. The approximately $500 million figure cannot be treated as a revenue forecast for ground-based facilities alone.
Quantum Computing Demand and the Distance to Lunar Mining Plans
Superconducting qubits operate at temperatures below 10 mK to suppress thermal excitation. According to the National Academies of Sciences, Engineering, and Medicine, modern dilution refrigerators circulate a mixture of helium-3 and helium-4 in a closed loop, typically cooling from room temperature to base temperature in 36 to 48 hours. While helium-3 is not consumed like fuel during operation, an increase in the number and capacity of refrigerators does increase the inventory needed for initial filling and replenishment.
Summarizing supply and demand with the single word "shortage" risks obscuring how circumstances have changed from the past. According to NIDC, demand surged to 70,000 liters annually in 2008 due to a rapid increase in neutron detectors for homeland security, exceeding government supply at the time. Since then, alternative detectors and reuse practices have advanced, bringing current federal demand forecasts down to under 6,000 liters annually. The DOE anticipates being able to meet critical federal demand for decades to come. What is driving current investment is not this past crisis—which has since been resolved—but rather forecasts of future growth in commercial quantum refrigerators.
Ground-based Cold Capture also connects to Interlune's stated goal of lunar mining. However, what the two share is only the final step: isotope separation of extracted helium. On the Moon, the process would require excavating regolith, heating it to release gases embedded by solar wind, pre-processing this gas, and then feeding it into the separation equipment. Power requirements and dust management differ from terrestrial conditions, and autonomous maintenance and transport back to Earth fall entirely outside the scope of ground-based experiments.
Whether Cold Capture becomes a viable ground-based supply system will be determined by continuous operation connected to liquefaction plants. If the estimated ceiling of 2.5 kilograms can be replaced with measured recovery rates and per-kilogram costs, helium-3 could expand its role from a byproduct of nuclear material management to a recovered product of industrial gas production.