A quiet but high-stakes experiment in climate control is moving out of theory and into reality, and it’s raising more questions than answers. Behind closed doors, a startup called Stardust Solutions is working on an ambitious and controversial idea: cooling the planet by reflecting a fraction of the Sun’s rays back into space using particles released high in the atmosphere. Supporters say it could buy critical time in the fight against global warming, but critics warn it could also reshape weather patterns, shift political power over the climate, and introduce risks the world is not prepared to manage. As investors pour millions into what could become a new global industry, the question is no longer just whether the technology works but who gets to decide if it should ever be used at all.
Stardust Solutions unveils plan to cool Earth by reflecting sunlight
Stardust Solutions, an Israeli-U.S. startup, has stepped out of the shadows with a high-stakes plan to profit from cooling the planet by blocking the sun.
The company’s strategy relies on microscopic aerosol particles — each 125 times smaller than a single grain of sand — designed to act as tiny mirrors in the sky. Since 2023, Stardust has quietly raised $75 million from investors who are betting that as climate change worsens, desperate governments will eventually pay the startup to pump millions of tons of these particles into the stratosphere. Until now, the project was shrouded in such intense secrecy that scientists had to sign nondisclosure agreements just to look at the technology.
On May 14th, Stardust finally revealed its secret formula. The particles are made of amorphous silica and measure just 0.5 microns across, making them invisible without a microscope. The company also unveiled its blueprints for the specialized equipment needed to scatter these spherical particles 11 miles above the Earth and track them as they drift back down.
“Our premise from the start was that the only way sunlight reflection technology would be considered by governments is if we provided robust scientifically-based solutions to all the challenges and concerns and proved it to be safe, practical, and controllable,” Stardust CEO Yanai Yedvab said in a statement. “That is the mission we took upon ourselves, and the details we are releasing today represent a major step toward that goal.”
What exactly is amorphous silica made of?
Stardust is developing two variations of these amorphous silica-based particles.
According to a research summary, the first type is “fully bio-safe, manufacturable at scale today, and at a very advanced stage of validation.” The second version is a similar size but features a core made of calcium carbonate — the same material found in eggshells — which the company claims will block solar radiation even more effectively.
Safety and sustainability are central to the design. “Both designs are intentionally engineered to recycle into existing natural cycles after they settle to the ground,” the summary noted.
It is also important to note the type of material being used. The startup is utilizing amorphous silica, which has a completely different atomic structure than crystalline silica — the hazardous, reactive dust created when rocks are crushed or cut. Stardust is not using crystalline silica. According to the World Health Organization’s cancer research agency, amorphous silica is not known to pose a health risk to humans in low doses.
When could Stardust’s sunlight-blocking plan actually begin?
According to an investor presentation previously reported by POLITICO Magazine, the startup has pitched backers on a timeline for global full-scale deployment as early as 2035. By that time, the company projects it will be pulling in roughly $1.5 billion in annual revenue.
Why experts fear profit-driven climate control
A growing chorus of scientists and policymakers is waving a red flag over Stardust and the broader solar geoengineering industry. Their primary concern? A lack of global oversight could lead to dangerous misuse, especially as international relations grow increasingly strained.
Critics argue that a private, for-profit corporation like Stardust shouldn’t be the one calling the shots on a technology that affects the entire planet.
“This announcement is a clear example of why self-governance led by for-profit entities does not work,” said Shuchi Talati, the executive director of the Alliance for Just Deliberation on Solar Geoengineering, a nonprofit that works to give vulnerable nations and communities a voice in these climate debates.
Talati emphasizes that Stardust shouldn’t be graded on its own scorecard. “They cannot create their own principles and then applaud themselves for following them. They cannot define safety according to their own standards and then self-certify that they meet them. The field requires coordinated, legitimate, and independent research governance.”
The danger of letting private companies police themselves is a sentiment shared by former government officials as well. “It rarely works out well when those who develop globally significant technology are also in charge of governing it,” added Hannah Safford, who served as a White House climate policy adviser during the Biden administration.
What lies ahead for Stardust
Stardust has officially gone public with its findings, publishing six academic papers online that detail its silica particles and dispersal systems. While many of these papers were co-authored with researchers from top-tier universities, they have not yet undergone peer review — the crucial scientific step where outside experts rigorously test and critique the data before it can be formally accepted.
As the company works toward getting these papers published in official scientific journals, it is also focusing heavily on the commercial side of things. Stardust is actively seeking patents for its proprietary particles and tech, securing the intellectual property that forms the backbone of its multi-billion-dollar business strategy.
Source: Politico