Saturday, 17 September 2011

CCAB@Origins 2011: Siliceous fragments in cometary IDPs


   Nori Miyake, Max Wallis + Chandra Wickramasinghe
Cardiff's collection of interplanetary micro-dust contains numerous siliceous fibres and whiskers, single or in complexes, some embedded in cometary aggregates. Hollow cylindrical fibres ~1x10µm, whiskers over ten times thinner, and EDX spectral carbon differentiates them from astrophysical mineral silicate particles. Similar fibres have been found in the Tagish Lake carbonaceous chondrite. We infer they are likely to originate from comets rather than other icy bodies.
see - our poster paper presented at the July 2011 conference (or click mini-poster on right).

CCAB@Origins 2011: Ices on comet Tempel-1

Icy morphologies seen in remnant lakes and centres of pedestal craters on Tempel-1 are dark because of cover by sublimation regolith. They imply melting of primordial dirty snow (fine grains of H2O, organics and clays) during an orbital phase closer to the Sun and via impact cratering. Ice areas began as depressed features, then evolve into elevated features due to faster evaporative erosion of the adjacent areas under unstable crusts. The comet thus had near-surface liquid water for periods.
see - our  Poster paper presented at the July 2011 conference (or click mini-poster on right).