Jan. 28, 1986 — Christa McAuliffe was the best thing about the final flight of the space shuttle Challenger. A schoolteacher from Concord, N.H., she survived a punishing selection process to become the first truly civilian astronaut, someone who would democratize space travel, empower women and girls, and boost the profile of the nation's underappreciated schoolteachers. But an unreliable spacecraft fueled by multiple rockets, some of them protected by brittle O-rings, was not the way to make that point. McAuliffe and her six crewmates flew for only 73 seconds before it all came apart. It was easily NASA's blackest day — all the more so because it needn't have been.