On July 20, 1969, two men born on Earth set foot on the moon. And, since they came safely home, then-President Nixon had no use for the speech In Event of Moon Disaster, prepared by William Safire. The full original text is here (pdf), but I found it appropriate for today, when we do have tragedy to mourn in memorial:
(abridged and slightly modified for the occasion)
These seven men and women lay down their lives in mankind’s most noble goal: the search for truth and understanding.
They will be mourned by their families and friends; they will be mourned by their nation; they will be mourned by the people of the world; they will be mourned by a Mother Earth that dared send her sons and daughters into the unknown.
In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood