In the ninth episode of the second season of The West Wing, Sam Seaborn the fictional White House Deputy Communications Director, finds himself arguing the merits of space exploration with the daughter of the Chief of Staff. His answer, written by Aaron Sorkin, is priceless. I thought of this exchange while watching Curiosity land on Mars two nights ago.
Sam Seaborn: There are a lot of hungry people in the world, Mal, and none of them are hungry ’cause we went to the moon. None of them are colder and certainly none of them are dumber ’cause we went to the moon.
Mallory O’Brian: And we went to the moon. Do we really have to go to Mars?
Sam Seaborn: Yes.
Mallory O’Brian: Why?
Sam Seaborn: ‘Cause it’s next. ‘Cause we came out of the cave, and we looked over the hill and we saw fire; and we crossed the ocean and we pioneered the west, and we took to the sky. The history of man is hung on a timeline of exploration and this is what’s next.
It’s not verbose, it’s not scientific, but its simple philosophy is flawless. What’s next?
Thoughts at Large 
So true.