by Jennifer Wilson, CBCNews.ca

The U.S. Department of Defense wants you . . . to invent a wearable power source for soldiers that can last for four days.

The department is sponsoring a competition where contestants design a prototype battery pack to power military equipment in the field, such as radios, night vision goggles and global positioning systems.

The winning power source must operate continuously for 96 hours, weigh less than 8.8 pounds and be wearable. The lightest system will win, and in the case of identical weights, the winner will be the thinnest system.

Prizes will be awarded in fall 2008, with $1 million US for first place, $500,000 for second and $250,000 for third.

There will be a technical briefing in Washington in September for potential contestants, and registration closes Nov. 30, 2007. The competition is open to international contestants, but the team leader must be a U.S. citizen.