NASA is marking the 25th anniversary of the space shuttle Challenger accident that killed seven astronauts.Families and NASA officials gathered at an outdoor memorial at Florida's Kennedy Space Center on Friday morning. Twenty-five years ago, the Challenger exploded shortly after liftoff. The seven astronauts who perished included schoolteacher Christa McAuliffe. One of the speakers was the widow of Challenger's commander, June Scobee Rodgers. She was instrumental in establishing the Challenger Center for Space Science Education, which now has 48 learning centers. Rodgers said the whole world saw how the astronauts died. She said the astronauts' families started the centers to show the world how Challenger's crew lived and why they risked their lives.
