About 230 years ago, molten lead that rained from the sky—historically something to avoid at all costs—became a clever new way to manufacture an important commodity: shotgun ammo.
Precisely round pellets fly straighter, but casting each in its own 1/8-inch mold isn’t exactly mass production. In space, making them would be easy. In zero gravity, surface tension pulls any liquid into a sphere, the shape with the least surface area for a given volume. This is as true for molten metal as it is for drops of water floating inside the space shuttle. On Earth, the closest thing to zero gravity is freefall—falling objects experience weightlessness right up until they hit the ground.
Replicating this is easy, except for the six-story height. I used my hydraulic lift to get about 40 feet up, but that wasn’t enough; the lead was still molten when it hit the water, and I didn’t get good pellets. (I decided not to climb to the top of my windmill with a pan of molten lead. Sorry, you’ll have to live without photos of perfect modern drop shot.)
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Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.