Firing particle-loaded rockets into the sky and spraying chemicals from airplanes are just a couple of ways scientists are already attempting to boost rainfall in drier regions of the world. But they may soon have a new tool at their disposal, with researchers in the US successfully testing a cloud-seeding drone aimed at offering a cheaper and safer alternative.

Built by manufacturer Drone America, the "Sandoval Silver State Seeder" recently took to the skies over Nevada, carrying cloud-seeding gear along for the ride. The flight is claimed to be the first time fixed-wing unmanned aircraft has been successfully tested with such a payload on board.

The drone flew to an altitude of 400 ft (122 m) in an 18-minute flight, deploying two silver-iodide flares in the process. Silver iodide is a material commonly used in cloud-seeding programs as it has a hexagonal crystalline structure is very similar to ice that triggers freezing nucleation, a process whereby smaller droplets gather around the particles to form blocks of ice.

China used this method of weather control in preparation for the opening ceremony of the 2008 Olympic Games, with organizers firing rockets into the sky to trigger downfalls around, but not over, the Olympic stadium. Australia disperses silver iodide by manned aircraft to manage dam water levels, while the technique is also used in many other locations around the world, from Los Angeles to India.

But by relying on drones to do the job, this process could potentially become cheaper and safer, according to the Desert Research Institute (DRI), which is carrying out the research. It has gained approval from the Federal Aviation Administration to test its aircraft at altitudes of up to 1,200 ft (365 m) as it looks to one day make it rain by way of flying robots.

"We have reached another major milestone in our effort to reduce both the risks and the costs in the cloud seeding industry and help mitigate natural disasters caused by drought, hail and extreme fog," says Mike Richards, President and CEO of Drone America. "With a wingspan of 11-feet, 10-inches (3.6 m) and its light weight design (less than 55 pounds (25 kg)) the Savant is the perfect vehicle to conduct this type of operation due to its superior flight profile, long flight times and its resistance to wind and adverse weather conditions."

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