Design techniques honed at NASA's Jet Propulsion Laboratory in Pasadena, Califonia for the twin Mars rovers, Spirit and Opportunity, were used to create the rovers currently examining the inside of Japan's nuclear reactors, in areas not yet deemed safe for human crews. The rovers currently taking radioactivity readings in the damaged Fukushima Daiichi nuclear power plant buildings, are equipped with multiple cameras and hazard material sensors. The images and readings provided by the rovers indicate that radiation levels are still too high to allow human repair crews to safely enter the buildings.