• Chemical identification of comet 81P/Wild 2 dust after interacting with molten silica aerogel

      Rietmeijer, F. J. M. (The Meteoritical Society, 2009-01-01)
      Flight aerogel in Stardust allocation C2092,2,80,47,6 contains percent level concentrations of Na, Mg, Al, S, Cl, K, Ca, Cr, Mn, Fe, and Ni that have a distinctive Fe- and CI-normalized distribution pattern, which is similar to this pattern for ppb level chemical impurities in pristine aerogel. The elements in this aerogel background were assimilated in non-vesicular and vesicular glass with the numerous nanometer Fe-Ni-S compound inclusions. After correction for the background values, the chemical data show that this piece of comet Wild 2 dust was probably an aggregate of small (<500 nm) amorphous ferromagnesiosilica grains with many tiny Fe,Ni-sulfide inclusions plus small Ca-poor pyroxene grains. This distinctive Fe- and CI-normalized element distribution pattern is found in several Stardust allocations. It appears to be a common feature in glasses of quenched aerogel melts but its exact nature is yet to be established.