NASA Administrator Jim Bridenstine, NASA employees, and members of the public bow their heads at the Space Shuttle Challenger and Columbia memorials during a wreath laying ceremony as part of NASA's Day of Remembrance, Thursday, February 7, 2019, at Arlington National Cemetery in Arlington, Va. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)