By the 40th anniversary of the Lewis and Clark expedition, the Oregon Trail was carrying settlers to the West. By the 40th anniversary of the completion of the transcontinental railroad, a web of rail traffic crisscrossed the continent. By the 40th anniversary of Lindbergh's epic transatlantic flight, thousands of people in jetliners retraced his route in comfort and safety every day. And on the 40th anniversary of Sputnik, hundreds of satellites were orbiting the Earth.

Only in human spaceflight do we celebrate the anniversary of an achievement that seems more difficult to repeat than to accomplish the first time. Only in human spaceflight can we find in museums things that most of us in the space business wish we still had today.

The United States spent eight years and $21 billion -- around $150 billion today -- to develop a transportation system to take people to the moon. We then spent less than four years and $4 billion using it, after which we threw it away. Not mothballed, or assigned to caretaker status for possible later use. Destroyed. Just as the Chinese, having explored the world in the early 15th century and found nothing better than what they had at home, burned their fleet of ships.