NASA personnel watch the guard-change ceremony at the Tomb of the Unknowns by as part of NASA's Day of Remembrance, Thursday, Jan. 28, 2021, at Arlington National Cemetery in Arlington, Va. 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)

NASA personnel watch as a wreath is laid at the Tomb of the Unknowns by acting NASA Administrator Steve Jurczyk as part of NASA's Day of Remembrance, Thursday, Jan. 28, 2021, 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/Bill Ingalls)

Acting NASA Administrator Steve Jurczyk, NASA personnel and others are seen in this black and white infrared photograph as they observe a moment of silence during a wreath laying ceremony as part of NASA's Day of Remembrance, Thursday, Jan. 28, 2021, 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/Bill Ingalls)

Acting NASA Administrator Steve Jurczyk speaks to NASA personnel and others during a wreath laying ceremony as part of NASA's Day of Remembrance, Thursday, Jan. 28, 2021, 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/Bill Ingalls)