When a mine collapses, it’s often silence that kills. After the 2006 Sago explosion, for example, rescuers blindly probed the earth as 13 West Virginia miners hammered a ceiling bolt for help. All but one suffocated. In response, Congress required coal mines to install wireless communication systems. But that has proved to be a tricky mandate: explosions can result when high-voltage electricity—the kind needed to power through thousands of feet of rock—connects with methane, and traditional routers need line-of-sight contact (rare in a mine).
Now, with the deadline for implementation less than a year away, a few ideas are showing promise. One uses magnetic waves to safely pierce the stone. But perhaps the leading contender, says Dave Chirdon, a senior official with the Mine Safety and Health Administration, reroutes signals to the surface via a series of “nodes”; when one fails, the transmission skips to another. If this system proves itself, mining disasters will still be bad—just not as hopeless.