Understanding the comet Wild 2 mineralogy in samples from the Stardust mission

摘要

The status of the solid materials and mineralogical and petrological results of the Stardust mission to comet 81P/Wild 2 are presented. This mission became the first successful sample-return mission since the Apollo project. This time the challenges were much less related to the availability of state-of-the-art analytical capabilities. Still, dedicated tools had to be developed to manipulate the samples that were all firmly embedded in the tracks they made when decelerating in the silica aerogel tiles of the collector. The comet particles were loosely bonded aggregates that shed their grains along the entire length of these tracks. It appears that most of the original comet minerals survived but interactions of debris with melted aerogel occurred and new minerals were made, adding to the incredibly, and unanticipated, diversity of the comet minerals, including some that so far were known only in meteorites. The latter alone showed that transport distances in the solar nebula extended all the way out to beyond Pluto into the Kuiper Belt of icy, comet-like, bodies. The full extent of the scientific yield of this mission is still unknown, promising but stressing current models of the formation of solar systems.