The Associated Press is reporting that two PackBot ground robots from iRobot have entered Unit 1 and Unit 3 of the crippled Fukushima nuclear power plant and performed readings of temperature, oxygen levels, and radioactivity. The data from the robots, the first measurements inside the reactors in more than a month since a massive earthquake and tsunami damaged the plant, revealed high levels of radioactivity -- too high for humans to access the facilities. The remote-controlled robots entered the two reactors over the weekend. Details of the mission -- such as what areas of the reactors the robots inspected and from where they were operated -- are still scarce, but Tokyo Electric Power Co. (TEPCO), the plant's operator, said that the robots opened and closed "double doors and conducted surveys of the situation" inside the buildings.