Elemental abundances in interplanetary dust

IT is generally believed that the main fraction of dust in the interplanetary medium is generated by the gradual disintegration of short-period comets in the inner Solar System^1,2. Analysis of interplanetary dust-grains is, accordingly, a technique for gathering information on the nature of cometary matter. Until now, however, no particle with an unarguable interplanetary origin has been subjected to detailed chemical analysis.