University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, April 9, 2007
Coffee, Tea & Snacks 4:15-4:30 PM

Michael Mumma
Goddard Space Flight Center
Comets, and implications for delivery of water and pre-biotic organics to Young Planets (and a bit of Atomic-Molecular Physics, too!)

As messengers from the early Solar system, comets encode information from the time of planet formation and even earlier - some may contain material formed in our natal interstellar cloud. Along with water, the cometary nucleus contains ices of natural gases (CH4, C2H6), alcohols (CH3OH), acids (HCOOH), embalming fluid (H2CO), and even anti-freeze (ethylene glycol). Cometary dust contains abundant refractory organics and silicates. During the first 500 million years of Earth's existence, comets could have delivered vast quantities of pre-biotic organic chemicals along with much (most?) water for our oceans. Did this enable the emergence of life? How does the compositional diversity of comets clarify nebular processes such as radial migration, dynamical scattering, and chemical processing? What are the implications for planetary systems around other stars? "Origin and Evolution" issues aside, comets provide natural laboratories for investigating a wide-range of atomic and molecular phenomena, such as charge-transfer-excitation (X-rays), dissociative excitation (prompt emission), fluorescence spectroscopy of low temperature gases, and nuclear-spin conversion. I will provide a simplified overview of this broad topic.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Catha Stewart at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.