After 13 miners were trapped in a coal mine in Sago, West Virginia, four years ago, rescuers didn’t know where to look for survivors -- they could have been anywhere between 11,000 and 13,000 feet from the entrance. Radio waves can’t penetrate very far through rock, so there was no way to communicate with the miners.
A new system developed by Lockheed Martin aims to change that, by using magnetic waves to carry voice and text messages.
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.