Seeds of life found in dust.

Interplanetary dust particles may rank among the oldest materials in the solar system. Now, for the first time, researchers have detected polycyclic aromatic hydrocarbons --a key family of organic molecules - in the dust. The discovery supports suggestions that tiny dust particles from outer space helped seed Earth with the chemicals necessary for life.

Two teams collaborated on the analysis of dust, which was collected by a NASA aircraft. At Washington University in St. Louis, Robert M. Walker and his colleagues measured the abundance of different isotopes of the same element to conclude that the dust truly originated outside Earth. At Stanford University, a group including Simon J. Clemett and Richard N. Zare vaporized and then ionized organic molecules in the dust. Sorting the ions with a mass spectrometer, the scientists concluded that they had indeed detected polycyclic aromatic hydrocarbons.