'All mankind is in their debt' 02/04/2003 By BRUCE NICHOLS / The Dallas Morning News HOUSTON - The lives of the seven Columbia astronauts were celebrated Tuesday in a short, somber service laced with Old Testament wisdom and attended by thousands who remembered them as explorers who dared to dream. "Today we remember not only one moment of tragedy but seven lives of purpose and achievement," President Bush said at the service. "To leave behind Earth and air and gravity is an ancient dream of humanity - for this seven it was a dream fulfilled." AP President Bush wipes...