The goal of the Stardust mission was to return both particle samples from Comet Wild 2 and from interstellar dust. By returning these samples to Earth for analysis a great deal is expected to be learned about the composition of the building blocks of the early solar system and our neighboring local stellar medium. Stardust returned these samples to Earth in January 2006.
Scientists have found a wide range of compositions and structures for the comet Wild 2 particles that were captured and returned to Earth by NASA's Stardust spacecraft. Their findings indicate the formation of at least some comets may have included materials ejected from the inner solar system to the far and cold outer edge of the solar nebula.