Curiosity, the NASA Mars rover, has not found the building blocks of life in that planet’s dirt, the agency said Thursday. “Rumors and speculation that there are major new findings from the mission at this early stage are incorrect,” NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. Tamping down expectations about a news conference scheduled for Monday, NASA said, “The instruments on the rover have not detected any definitive evidence of Martian organics.” Speculation was fueled last week when the mission’s project scientist told a reporter that data from Curiosity would be “one for the history books.” NASA later clarified that the scientist was speaking generally.