The Stardust Mission: Analyzing Samples from the Edge of the Solar System

Comet samples returned to Earth by the NASA Stardust mission have provided a surprising glimpse into the nature of early Solar System materials and an epiphany on the origin of the initial rocky materials that once filled the cold regions of the solar nebula. The findings show that the cold regions of the early Solar System were not isolated and were not a refuge where interstellar materials could commonly survive. Wild 2, the sampled comet, appears to be a typical active Jupiter family comet, and yet most of its sampled micron and larger grains are familiar high-temperature meteoritic materials, such as chondrule fragments, that were transported to cold nebular regions. The rocky components in primitive asteroids and comets may differ because asteroid formation was dominated by local materials, whereas comets formed from mixed materials, many of which were transported from very distant locations.