In a 2023 pitch to investors, a "well-financed, highly credentialed" startup named Stardust aimed for a "gradual temperature reduction demonstration" in 2027, [1]according to a massive new 9,600-word article from Politico . ("Annually dispersing ~1 million tons of sun-reflecting particles," says one slide. "Equivalent to ~1% extra cloud coverage.")

"Another page told potential investors Stardust had already run low-altitude experiments using 'test particles'," the article notes:

> [P]ublic records and interviews with more than three dozen scientists, investors, legal experts and others familiar with the company reveal an organization advancing rapidly to the brink of being able to press "go" on its planet-cooling plans. Meanwhile, Stardust is seeking U.S. government contracts and quietly building an influence machine in Washington to lobby lawmakers and officials in the Trump administration on the need for a regulatory framework that it says is necessary to gain public approval for full-scale deployment....

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> The presentation also included revenue projections and a series of opportunities for venture capitalists to recoup their investments. Stardust planned to sign "government contracts," said a slide with the company's logo next to an American flag, and consider a "potential acquisition" by 2028. By 2030, the deck foresaw a "large-scale demonstration" of Stardust's system. At that point, the company claimed it would already be bringing in $200 million per year from its government contracts and eyeing an initial public offering, if it hadn't been sold already.

The article notes that for "a widening circle of researchers and government officials, Stardust's perceived failures to be transparent about its work and technology have triggered a larger conversation about what kind of international governance framework will be needed to regulate a new generation of climate technologies." (Since currently Stardust and its backers "have no legal obligations to adhere to strenuous safety principles or to submit themselves to the public view.")

In October Politico spoke to Stardust CEO, Yanai Yedvab, a former nuclear physicist who was once deputy chief scientist at the Israeli Atomic Energy Commission. Stardust "was ready to announce the $60 million it had raised from 13 new investors," the article points out, " [2]far larger than any previous investment in solar geoengineering."

> [Yedvab] was delighted, he said, not by the money, but what it meant for the project. "We are, like, few years away from having the technology ready to a level that decisions can be taken" — meaning that deployment was still on track to potentially begin on the timeline laid out in the 2023 pitch deck. The money raised was enough to start "outdoor contained experiments" as soon as April, Yedvab said. These would test how their particles performed inside a plane flying at stratospheric heights, some 11 miles above the Earth's surface... The key thing, he insisted, was the particle was "safe." It would not damage the ozone layer and, when the particles fall back to Earth, they could be absorbed back into the biosphere, he said. Though it's impossible to know this is true until the company releases its formula. Yedvab said this round of testing would make Stardust's technology ready to begin a staged process of full-scale, global deployment before the decade is over — as long as the company can secure a government client. To start, they would only try to stabilize global temperatures — in other words fly enough particles into the sky to counteract the steady rise in greenhouse gas levels — which would initially take a fleet of 100 planes.

This begs the question: should the world attempt solar geoengineering?

> That the global temperature would drop is not in question. Britain's Royal Society... said in a report issued in early November that there was little doubt it would be effective. They did not endorse its use, but said that, given the growing interest in this field, there was good reason to be better informed about the side effects... [T]hat doesn't mean it can't have broad benefits when weighed against deleterious climate change, according to Ben Kravitz, a professor of earth and atmospheric sciences at Indiana University who has closely studied the potential effects of solar geoengineering. "There would be some winners and some losers. But in general, some amount of ... stratospheric aerosol injection would likely benefit a whole lot of people, probably most people," he said. Other scientists are far more cautious. The Royal Society report listed a range of potential negative side effects that climate models had displayed, including drought in sub-Saharan Africa. In accompanying documents, it also warned of more intense hurricanes in the North Atlantic and winter droughts in the Mediterranean. But the picture remains partial, meaning there is no way yet to have an informed debate over how useful or not solar geoengineering could be...

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> And then there's the problem of trying to stop. Because an abrupt end to geoengineering, with all the carbon still in the atmosphere, would cause the temperature to soar suddenly upward with unknown, but likely disastrous, effects... Once the technology is deployed, the entire world would be dependent on it for however long it takes to reduce the trillion or more tons of excess carbon dioxide in the atmosphere to a safe level...

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> Stardust claims to have solved many technical and safety challenges, especially related to the environmental impacts of the particle, which they say would not harm nature or people. But researchers say the company's current lack of transparency makes it impossible to trust.

Thanks to long-time Slashdot reader [3]fjo3 for sharing the article.



[1] https://www.politico.com/news/magazine/2025/11/21/stardust-geoengineering-janos-pasztor-regulations-00646414?nid=0000014f-1646-d88f-a1cf-5f46b7bd0000&nname=playbook&nrid=00000157-90cc-d19a-afd7-fbff07390002

[2] https://srm360.org/funding-tracker/

[3] https://www.slashdot.org/~fjo3