Astrobiology
Two Columns
Theme III
Overview 06.18.2005
Marla Moore's Lab
Theme III conducts laboratory simulations of processes that likely affected the chemistry of material in natal insterstellar cloud cores and in protoplanetary disks.
What chemical processes are in effect in stellar nurseries? How do grains of microscopic proportions catalyze chemical reaction s to produce organic compounds? Co-Investigators in Theme III perform laboratory experiments to better understand these and other questions.
Cosmic Ice Laboratory
Co-Investigator Jason Dworkin studies the energetic processing of interstellar ice analogs in the laboratory produce molecules of importance in current living organisms, including quinones, amphiphiles, and amino acids. Quinones are essential in vital metabolic roles such as electron transport. Studies show that quinones should be made wherever polycyclic aromatic hydrocarbons are precessed in interstellar ices. Amphiphiles are also made when mixed molecular ices are irradiated. These amphiphiles self-assemble into auto-fluorescent vesicles when placed in liquid water, as do Murchison extracts). Photolysis of plausible ices can also produce alanine, serine, and the glycerol-glyceric acid-glycine series. This suggests that some of the oxidized aromatics, amphiphiles, amino acids, hydroxy acids, and other compounds found in meteorites may have preceded parent body aqueous alteration. Astrobiology Analytical Laboratory
Auto-fluorescent vesicles
Co-Investigator Bruce Fegley develops computer codes for chemical kinetic calculations in the solar nebula as a function of temperature, pressure, and mixing rate, parameterized as an eddy diffusion coefficient. Existing codes developed for similar calculations in the atmospheres of gas giant planets will be modified for this purpose. He also performs experimental studies of the efficiency of different types of catalysts for conversion of CO + H2 to CH4. The catalysts studied include pure iron, meteoritic iron alloy, an ordinary chondrite, a commercial iron oxide based catalyst, pure platinum, and pure corundum.
Co-Investigators Marla Moore and Reggie Hudson perform laboratory investigations of the low temperature chemistry of acetonitrile, propionitrile, acrylonitrile, cyanoacetylene, and cyanogen (CH3CN, CH3CH2CN, CH2CHCN, HCCCN, and NCCN, respectively). They seek and find trends in the photo- and radiation chemical products of these molecules at 12 - 25 K. In the absence of water, all of these molecules isomerize to isonitriles, and CH3CN, CH3CH2CN, and (CH3)2CHCN also form ketenimines. In the presence of H2O, no isonitriles are detected but rather the isocyante ion (OCN-) is seen in all cases. Although isonitriles, ketenimines, and OCN- are the main focus of this work, they also examine cases of hydrogen loss to make smaller nitriles, and hydrogen addition (reduction) to make larger nitriles. HCN formation is seen in most experiments. Their results are directly applicable to the nitrile ice chemistry on Titan, in cometary ice, and in the interstellar medium.
Co-Investigator Joe Nuth performs studies of the catalytic efficiency of amorphous iron silicate and magnesium smokes in the conversion of CO, N2 and H2 gas mixtures into complex hydrocarbons. The process is greatly complicated due to the deposition of a reactive carbonaceous coating onto the surfaces of the amorphous grains that also acts to catalyze the conversion of both CO and N2 into complex organics. Analysis of this organic coating reveals a complex mixture of both aromatic and aliphatic hydrocarbons, similar in many respects to that found in primitive meteorites. Amorphous iron silicates easily convert CO plus H2 gas mixtures to methane plus more complex hydrocarbons as well as N2 plus H2 mixtures to ammonia. Amorphous magnesium silicates convert CO plus H2 mixtures to methane and more complex hydrocarbons less efficiently than do iron silicates and can not initially produce reduced nitrogen compounds until a significant quantity of carbonaceous contaminant has been deposited onto the grain surface. This contaminant is obviously capable of reacting with N2, though not as efficiently as does the amorphous iron silicate.
More Research
NASA Fact
On January 31, 1958, Explorer 1 became the first artificial satellite launched into space by the United States. Onboard was a cosmic ray detector designed to measure the radiation environment in Earth orbit.
