LPL Colloquium: Dr. Lindsay P. Keller

Tuesday, Oct 23, 2012
3:45 pm
Location: Kuiper Space Sciences
Room: 308

Dr. Lindsay P. Keller
Johnson Space Center

"Cometary Dust: A Window to the Early Solar System"


Comets formed in the Kuiper Belt have long been considered to harbor the best preserved remnants of the Solar System starting materials because they accreted at >30 AU, where temperatures were on the order of 30 K. The small sizes of most comets and their origins in the outermost regions of the Solar System protected them from both significant internal heating by radioactive heat sources and nebular heating. Consequently, comets have escaped the extensive thermal and aqueous processes that have modified or destroyed most of the Solar System starting materials in meteorites. Cometary materials are likely to harbor the best preserved remnants of interstellar silicates and other building blocks of the Solar System.

Cometary dust samples have been the subjects of intensive laboratory study, both in the form of interplanetary dust particles (IDPs) collected in the Earth's stratosphere and direct samples of comet 81P/Wild-2 returned by the Stardust spacecraft. While the specific parent bodies of individual IDPs are unknown, the anhydrous chondritic-porous (CP) subset has been linked directly to cometary sources based on their compositions, dynamical histories, and infrared spectra. Other clear indications of the primitive nature of CP IDPs is their relatively high abundances of presolar materials including circumstellar silicates and preserved molecular cloud organic matter. Coordinated mineralogical, chemical and isotopic studies of these particles are used to establish the origins of their various components.

Host: Tom Zega