Your ski buddy has a 92 percent chance of survival after being buried for 15 minutes and a 30 percent chance after 35 minutes. Your search had best be efficient. Whereas most transceivers use confusing audio-based directional cues, the S1's electromagnetic sensors map victims' positions and depths on an LCD screen. The S1 gives signatures for up to four people-crucial for multiple burials. $650
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.