Interlune packs 15,000 years of solar wind into a four-hour test

A Seattle company compressed 15,000 years of space weather into a four-hour lab session. Interlune, which wants to mine helium-3 on the Moon, built a vacuum chamber that fires ionized helium into lunar regolith simulant at a rate far beyond anything the real Moon experiences, replicating millennia of solar wind exposure in an afternoon, Ars Technica reported.

Helium-3 forms inside the Sun as a byproduct of nuclear fusion, and some of it escapes as part of the solar wind, a constant stream of charged particles moving outward through the solar system. The Moon has no magnetic field or atmosphere to block that wind, so helium-3 has been striking its surface for billions of years, embedding itself in the lunar soil. Meteorite impacts periodically churn that soil, mixing some of the helium slightly below the surface. Concentrations stay low, roughly 10 to 20 parts per billion in titanium-rich soils that hold onto the ions better, but that's still far more than Earth retains, since our planet's magnetic field and atmosphere shield it from most of the same wind.

The appeal goes beyond curiosity. Geologist and Apollo 17 astronaut Harrison "Jack" Schmitt has argued for decades that helium-3 could eventually fuel fusion reactors. Nearer-term, it has real uses in cooling materials to ultra-low temperatures, medical research, and neutron detection, which makes it one of the only lunar materials that could plausibly get mined and shipped back to Earth at a profit.

Testing extraction hardware for that job runs into a supply problem. Johnson Space Center holds a bit over 300 kilograms of pristine Apollo-era regolith, and NASA has little reason to hand commercial companies enough of it to damage or destroy during testing. Most lunar simulants on the market copy the geology and dust behavior of regolith without matching its precise chemistry, which leaves helium-3 extraction hardware essentially untested against the material it needs to process.

Interlune's science team, led by planetary scientist Elizabeth Frank, built its way around that scarcity instead of waiting on it. Inside a vacuum chamber at the company's offices, the team accelerated ionized helium into lunar regolith simulant, mimicking the solar wind's exposure at a dramatically higher rate. Four hours of bombardment delivered the equivalent of 15,000 years of natural solar wind implantation.

The team then heated the treated material and watched it decompose through pyrolysis, tracking the temperatures at which the implanted helium released. Those temperatures matched what scientists have already measured in real lunar rocks brought back by Apollo astronauts, giving Interlune confidence its simulant behaves like the genuine article.

• Helium-3 concentration in lunar regolith: roughly 10-20 parts per billion in titanium-rich soils
• Real Apollo regolith held at Johnson Space Center: a bit over 300 kilograms
• Solar wind exposure replicated: 15,000 years, compressed into four hours
• Verification method: pyrolysis, matched against helium release temperatures from real Apollo samples

Interlune plans to use the new simulant to test the hardware it's developing to extract and process helium-3 on the Moon, and it will sell the simulant to other lunar mining companies chasing the same problem. The goal is to finish testing everything on Earth, under conditions that match the Moon as closely as physics allows, before sending a prototype mission on a lunar lander later this decade.

Interlune's bet sits alongside a broader wave of private capital moving into space infrastructure. Intokened covered a similar dynamic this week when SpaceX committed $100 billion to build the world's largest spaceport in Louisiana, a reminder that lunar mining hardware is only one piece of a much larger buildout racing to make space commercially viable within this decade.

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