Sugars, Alcohols, and Cometary Astrobiochemistry

Radio and IR observations have revealed that a rich organic chemistry exists in comets and in a variety of interstellar regions. Among the organic molecules detected are acids, alcohols, aldehydes, ketones, and nitriles. The simplest sugar, glycolaldehyde, has been reported (Hollis et al., ApJ, 2000, 540, L107), as has an amino acid, glycine (Kuan et al., ApJ, 2003, 593, 848; but see Hollis et al., ApJ, 2003, 588, 353). Gas-phase reactions to produce many of these molecules are not well understood, and solid-phase chemistry is thought to make an important contribution. To better understand organic chemistry in cold cosmic environments, we have performed photo- and radiation chemical experiments on icy materials at 10 - 100 K. Gas-phase molecules are frozen in a vacuum chamber, and then exposed to either MeV protons or vacuum-UV photons to mimic cosmic-ray bombardment or cosmic-UV exposure, respectively. Changes in ice composition are followed in situ with IR spectroscopy. In this AGU presentation we will describe our latest results for glycolaldehyde, as well as a few prebiological organics. Solid-state IR spectra and reaction pathways will be presented, and predictions will be made for the chemical composition of selected Solar System objects. -- This research is funded through NASA's Planetary Atmospheres and SARA programs, and through the NASA Astrobiology Program under RTOP 344-53-51-01 to M. J. Mumma (NASA GSFC).