The nature of early solar system and presolar materials

Remnants of the materials that were present at the formation of the early solar system are preserved in cometary dust particles collected in the Earth's stratosphere. Coordinated analyses of these materials using ion and electron beam instruments have identified preserved circumstellar silicates, supernova grains, and molecular cloud organic matter within the particles. These exotic grains have isotopic compositions that lie far outside the range exhibited by solar system materials. The mineralogy, composition, and microstructure of the presolar grains provide additional insights their sources and formation. The laboratory data serve as ground truth for astrophysical models based on spectroscopic measurements.