Stardust Solutions, founded in 2023 by former Israeli nuclear physicists, is advancing solar geoengineering by developing particles made from amorphous silica and calcium carbonate to reflect sunlight. The company says deploying one million tons annually could lower global temperatures by 0.9°F at a cost of $10 billion, but experts question the safety and governance of such interventions. Critics highlight risks like altered weather patterns, "termination shock," and the lack of transparency in proprietary, for-profit research. Stardust plans outdoor tests under government supervision, but past experiments have faced public backlash and bans.