I recently saw "In the Shadow of the Moon," a surprisingly moving documentary by Ron Howard that tells the story of the Apollo missions and their moon landings through the words of the astronauts who undertook those historic missions. The first trip to the moon was the first occasion, of course, that people around the world saw their own planet in perspective: "hanging small, bright and borderless," in the words of one of the Apollo crew. We've blogged plenty about the transformative power of this image.

But the moon (and the image of the earth that it elicits) remains an elusive destination since NASA's Apollo program fulfilled JFK's ambitious pledge to put a man there before the calendar struck 1970. The Cold War political one-upsmanship and novelty that motivated the first lunar missions has passed; we need new incentives.

Enter Google, chronic innovator:

Google's Lunar X Prize will put $20 million into the hands of the first privately funded team that can land a rover on the moon, have it travel on the surface for 500 meters or more, send back data, photos and video, and do it all by December 31, 2012.

It's a paltry sum that won't offset the cost of developing and executing a private sector lunar landing, but it's distinctly Kennedy-esque, challenging private teams to do something momentus within a discrete time-frame essentially for bragging rights.

Google understands something about advocacy: a big idea is hard to resist.