Families of the astronauts lost in the space shuttle Challenger accident are marking that tragic day 40 years ago. All seven on board were killed when Challenger broke apart following liftoff on Jan. 28, 1986. At Thursday's memorial ceremony at Florida's Kennedy Space Center, Challenger pilot Michael Smith's daughter, Alison, said through tears that her life forever changed that frigid morning, as did many other lives. Challenger's crew included schoolteacher Christa McAuliffe. Two of her fellow teacher-in-space contenders — both retired now — attended the memorial.
