The remote-controlled iRobot 510 PackBot by iRobot's Bedford, Mass. has a radioactivity sensor has been added to the robot, which can relocate up to 30 pounds of hazardous materials with its arm. Now its taking on another hazardous mission: exploring a reactor building at Japan's crippled Fukushima Daiichi nuclear plant.

The PackBot, a small robot that scoots around on tank-like treads, would monitor radiation and oxygen levels to find out whether conditions were safe enough to allow human workers to go in to try to bring the nuclear crisis at the plant under control.