LDEF: Chemical and isotopic measurements of micrometeoroids by SIMS

Described is a passive experiment for LDEF (Long Duration Exposure Facility) to measure the chemical and isotopic composition of interplanetary dust particles >10⁻¹⁰g for most of the major elements expected to be present. The detector consists of Ge targets covered with a metallized plastic film. During impact micrometeoroid vapor and melt are deposited on the underside of the foil which can be analyzed be secondary ion mass spectroscopy (SIMS) after the return of LDEF. Additional information on projectile mass, velocity and density can be obtained from the study of the penetration hole and the impact crater. Criteria for the choice of materials are given and first results of impact simulation experiments are reported which demonstrate the viability of the basic concept and show that isotopic data can be obtained from the deposits.