A synchrotron-based facility for the in-situ location, chemical and mineralogical characterization of ∼10 μm particles captured in aerogel

NASA’s Stardust mission collected dust from the coma of Comet Wild-2 on January 2nd, 2004, by direct capture into aerogel cells that flew through the dust coma at ∼6 km/s. Stardust collected several hundred comet particles >10 μm in size. These comet samples were delivered to Earth on January 15th, 2006. We developed a facility at the National Synchrotron Light Source at Brookhaven National Laboratory (Upton, NY, USA) for the in-situ characterization of ∼10 μm particles collected in aerogel. These analytical instruments allow us to perform extensive chemical, mineralogical, and size-frequency characterization of particles captured in aerogel. These analyses are conducted without any invasive extraction, minimizing the possibility of contamination or particle loss during preparation. This facility was used to determine the chemical composition, the oxidation state, the mineralogy and to provide an indication of the grain size of the Wild-2 particles before they were removed from the aerogel. This information provides a catalog of particle types, allowing a more reasoned allocation of the particles to subsequent investigators based on a relatively detailed knowledge of the chemical composition and mineralogy of each particle. These measurements allowed a comparison of the chemical and mineralogical properties of the Wild-2 particles with other types of extraterrestrial materials, including interplanetary dust particles and meteorites. The success of in-situ analysis for Wild 2 particles demonstrates that synchrotron-based facilities will be important for the analysis of particles collected in aerogel on future earth-orbiting satellites and spacecraft.