Forty years ago today, Neil Armstrong and Buzz Aldrin were the first humans to set foot on the Moon. Michael Griffin, former NASA Administrator, observed:What is most striking about this 40th anniversary of the first human landing on the moon is that we can no longer do what we're celebrating. Not "do not choose to," but "can't."By the 40th anniversary of the Lewis and Clark expedition, the Oregon Trail was carrying settlers to the West. By the...