A hard x-ray nanoprobe has been implemented at the synchrotron in Grenoble, France, allowing nondestructive trace element imaging of thick samples. Its advantages are nanometer spatial resolution on samples of several tens of micrometer, very high flux, and achromaticity. Nanometer imaging of a cometary grain from the Stardust mission shows the sensitivity and resolution gains obtained while radically changing our understanding of the composition of heterogeneous samples. The probe opens unique possibilities in the study of minute, fragile samples fundamental to the earth and planetary sciences, which until now were out of the reach of direct analytical methods.