The 123,000 MPH Plasma Engine That Could Finally Take Astronauts To Mars By Sam Howe Verhovek
Measuring time more precisely than ever By Erika Villani
Scientists deploy genetic forensics to protect overhunted animals By Laura Allen
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.