Stardust Solutions, an Israeli-American start-up developing technology to disperse reflective particles high in the atmosphere so that less sunlight reaches Earth, has raised $75m from investors and wants governments as customers.

The total includes a $60m round announced in October 2025 and led by Lowercarbon Capital, the climate technology investment firm co-founded by Chris Sacca. Other backers include Exor, the Agnelli family’s investment company and a major shareholder in Ferrari, along with Future Ventures, Future Positive, Lauder Partners, Attestor, Kindred Capital and former Facebook executive Matt Cohler.

Stardust was founded in March 2023 by Israeli physicists Yanai Yedvab, Amyad Spector and Eli Waxman. Yedvab and Spector previously worked as nuclear physicists for the Israeli government.

The company is registered in Delaware and headquartered outside Tel Aviv. It says it is not affiliated with the Israeli government.

Yedvab told Politico that investors were backing the idea that “we need a safe and responsible and controlled option for sunlight reflection.”

How the technology would work

Stardust’s approach is known as stratospheric aerosol injection. It sits within solar geoengineering, formally called solar radiation modification (SRM), which aims to reflect a small fraction of the sun’s energy back into space. Unlike carbon removal, it does not take carbon dioxide out of the atmosphere.

The idea draws on the effect of large volcanic eruptions, which can temporarily cool the Earth when sulphur compounds reach the stratosphere and form aerosols that reflect sunlight. Cooling was observed after Mount Pinatubo erupted in 1991, and scientists have discussed deliberately reproducing the effect for decades.

Rather than releasing sulphur dioxide, Stardust is developing proprietary reflective particles, alongside dispersal and monitoring technology, and is working towards aircraft-based systems.

The company has hired Washington lobbying firm Holland & Knight as it seeks a regulatory framework and potential US government contracts.

Stardust says it is pursuing research and development, not deployment. “Our goal is to turn SRM from a scientific concept into a safe and practical option,” the company said.

It argues that humanity may eventually need an emergency brake if cuts in emissions fail to prevent dangerous warming.

Criticism and other cooling projects

The Center for International Environmental Law (CIEL) criticised the company’s plans when the $60m financing was announced. Mary Church, CIEL’s geoengineering campaign manager, said: “Solar geoengineering is inherently unpredictable and risks further breaking an already broken climate system.”

In CIEL’s statement on the financing, Church added: “With uneven global impacts predicted, deployment would create winners and losers, undermining the rights of billions of people and raising the central question of who gets to control the global thermostat.”

CIEL also pointed to the risk of termination shock. Because solar geoengineering does not remove carbon dioxide, a pause or halt after decades of artificially suppressed warming could see temperatures rise rapidly.

Stardust is not the only company in the field. Make Sunsets, a small US start-up, launches weather balloons carrying sulphur dioxide into the stratosphere and sells what it calls “Cooling Credits”, under the slogan “Make Earth Cool Again”.

Other research efforts have been dropped. Harvard’s proposed SCoPEx experiment would have studied how tiny quantities of particles behave in the stratosphere. After years of controversy over governance and consent, Harvard announced in 2024 that it would not proceed.

The Arctic Ice Project explored spreading reflective hollow glass microspheres over Arctic sea ice to slow melting, before ending its research amid environmental and deployment concerns.

In Australia, researchers have experimented with marine cloud brightening around the Great Barrier Reef, spraying tiny seawater droplets upwards to make clouds more reflective and protect vulnerable coral.

In the UK, the Advanced Research and Invention Agency (ARIA) is running a £56.8m research programme to establish whether climate cooling approaches “could ever be feasible, scalable, safe, and governable”. The agency says it funds a limited number of small-scale, carefully controlled outdoor experiments where questions cannot be answered by models.

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