THE THERMAL HISTORY OF INTERPLANETARY DUST PARTICLES COLLECTED IN THEEARTHS STRATOSPHERE

Fragments of 24 individual interplanetary dust particles (IDPs) collec ted in the Earth's stratosphere were obtained from NASA's Johnson Spac e Center collection and subjected to pulse-heating sequences to extrac t He and Ne and to learn about the thermal history of the particles. A motivation for the investigation was to see if the procedure would he lp distinguish between IDPs of asteroidal and cometary origin. The use of a sequence of short-duration heat pulses to perform the extraction s is an improvement over the employment of a step-heating sequence, as was used in a previous investigation. The particles studied were frag ments of larger parent IDPs, other fragments of which, in coordinated experiments, are undergoing studies of elemental and mineralogical com position in other laboratories. While the present investigation will p rovide useful temperature history data for the particles, the relative ly large size of the parent IDPs (approximately 40 mum in diameter) re sulted in high entry deceleration temperatures. This limited the usefu lness of the study for distinguishing between particles of asteroidal and cometary origin.