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 of man.
In ancient days, we looked at stars and saw our heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood.
Per aspera ad astra, and Godspeed Columbia.