Google will pay up to $30 million in prize money to anyone able to land a privately funded spacecraft on the moon, because "it's cool," the company said on its blog.

"More seriously, space exploration has a remarkable history of producing technological breakthroughs," wrote Alan Eustace, senior vice president of engineering, on Google's blog. He cited ablative heat shields, asteroid mining, invisible braces, and the Tang orange drink as past achievements, and said the prize money could lead to further developments in robotics, new space-age materials, precision landing control technology, "and who knows what else."

Teams from around the world will vie for the Google Lunar X-Prize by building lunar missions complete with robotic rovers capable of roaming the surface of the moon for at least 500 metres and sending video, images and other data back to Earth, according to a statement from the X Prize Foundation.

The X Prize Foundation is best known for another space competition, the $10 million Ansari X Prize for private suborbital spaceflight, won by SpaceShipOne three years ago. Google teamed up with the foundation on the lunar project.

A grand prize of $20 million will go to the first team to land a privately funded spacecraft to the Moon and complete several tasks. Bonuses of up to $5 million can be earned from roaming an additional 5,000 metres on the surface of the Moon, finding and photographing man made artifacts left on the lunar surface, such as hardware from one of the Apollo missions, discovering water ice, and surviving a lunar night, a frigid affair lasting 14.5 Earth days, the foundation said. The remaining $5 million will be paid to the second place finisher in the competition.

Images from the lunar landing will be available online at the Google Lunar X Prize website.

There is a time limit to the competition. The value of the grand prize will drop to $15 million after 31 December 2012, and on 31 December, 2014 the contest will end unless extended by Google and the X Prize Foundation.