A Laboratory Approach to the Study of Extraterrestrial Molecules in Icy Environments
Wednesday, March 17, 2010 - 4:00pm
CCU Lecture Series, National Radio Astronomy Observatory, Charlottesville
NASA Goddard Space Flight Center, Astrochemistry Branch
Greenbelt, Maryland 20771
Research Page: http://science.gsfc.nasa.gov/691/cosmicice/hudson.html
Astronomical observations of both solar system and interstellar regions have revealed a rich chemical inventory that includes most classes of organic molecules and selected inorganics. For example, gas-phase ethylene glycol and SO2 have been observed by astronomers, while solid-phase detections include OCS, H2O2, and the cyanate anion. All of these are found in environments that are, by earthly standards, exceedingly hostile: temperatures of 10 - 100 K, minuscule densities, and near-ubiquitous ionizing-radiation fields. Beyond the simplest chemical species, these conditions have made it difficult to account for the observed molecular abundances using gas-phase chemistry, suggesting solid-phase reactions play an important role.
In extraterrestrial environments, cosmic rays, UV photons, and magnetospheric radiation all drive chemical reactions, even at cryogenic temperatures. To study this chemistry, laboratory astrochemists conduct experiments on icy materials, frozen under vacuum and exposed to sources such as keV electrons, MeV protons, and far-UV photons. Compositional changes usually are followed with IR spectroscopy and, in selected cases, more-sensitive mass-spectral techniques.
This presentation will review some results from our laboratory on both known and suspected extraterrestrial molecules and ions. Spectra and reaction pathways will be presented, and a few predictions made for interstellar chemistry and the chemistry of selected solar system objects.
Reggie L. Hudson is an astrophysicist in the Astrochemistry Branch at the NASA Goddard Space Flight Center. He received his A.B. in Chemistry and Mathematics from Pfeiffer University in 1974 and a Ph.D. in Physical Chemistry from the University of Tennessee in 1978. His research interests include the chemistry and physics of cosmic ices (cometary, icy satellite, and interstellar), radiation chemistry and photochemistry applied to astrochemical problems, and molecular spectroscopy, especially as applied to free radical structure and reactions. His past teaching efforts include: courses in physical chemistry, astrobiology, and astronomy; courses in introductory chemistry and in the history and methods of science; and courses in Eckerd College's Honors Program, for which Dr. Hudson served as the program's first director. He has published hundreds of papers in the most prestigious and widely read journals of Astronomy, Astrophysics, Chemical Education, and Astrobiology and has been selected as a manuscript and proposal reviewer for numerous journals and NASA programs. He is a member of the American Chemical Society (Chemical Education, Physical, and History Divisions), the Royal Society of Chemistry (Education and Faraday Divisions), the American Astronomical Society (Divisition for Planetary Sciences), the American Geophysical Union, and Sigma Xi.