NASA personnel, family members of those lost in Challenger, Columbia, Apollo 1 and members of the public watch as a wreath is laid at the Tomb of the Unknowns by NASA Administrator Charles Bolden as part of NASA's Day of Remembrance, Friday, Jan. 31, 2014, at Arlington National Cemetery. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Bill Ingalls)