After months of delays, the U.S. Air Force is about to launch the first of a new generation of GPS satellites, designed to be more accurate, secure and versatile. But some of their most highly touted features will not be fully available until 2022 or later because of problems in a companion program to develop…

Crumbling mine tunnels awash with polluted waters perforate the Colorado mountains, and scientists may one day send robots creeping through the pitch-black passages to study the mysterious currents that sometimes burst to the surface with devastating effects. One such disaster happened at the inactive Gold King Mine in southwestern Colorado in 2015, when the Environmental…