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.