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2003 Annual Science Report

University of Washington Reporting  |  JUL 2002 – JUN 2003

Delivery of Organics to Earth and Earthlike Planets - Brownlee and Kress

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

In collaboration with George Cody of Carnegie NAI lead team, Brownlee and Kress have found that organic material found in bulk meteorites (Murchison was the one used in this study) can be released into the gas phase when subjected to atmospheric entry conditions (flash-heating at a rate ~ 500 K/sec and peak temperature of 1000 K for a few seconds). Many of the more refractory organics found in Murchison are released without major chemical modification; other organics found in our experiments are apparently heat-modified daughter products of other compounds. Also released were significant amounts of CO2, H2O, CH4, SO2, H2S and other light gases, and a variety of light hydrocarbons. These compounds may have played important roles in the atmospheric chemistry of early Earth, during a time when the flux of micrometeorites was much higher than today. In particular, all of the compounds named above are greenhouse gases. We also found numerous small polycyclic aromatic hydrocarbons, which would have been excellent absorbers of ultraviolet (UV) radiation during a time when no ozone layer existed.

Over 250 200┬Ám diameter unmelted micrometeorites were identified and extracted from sediments recovered from the unique South Pole Water Well sample provided by collaborator Susan Taylor from CRREL in Hannover. Graciela Matrajt (an astrobio-supported Post Doc visiting from France) extracted the particles, crushed them and treated them with HF. Extreme efforts were used to limit and understand contamination. The samples were analyzed for amino acids at ASU by collaborator Sandra Pizzarello. AIB was discovered in these samples, the first amino acid detection in micrometeorites. The data are being studied to estimate the amount of amino acids and other organic materials delivered to the pre-biotic Earth at the time of the origin of life. The analyzed particles studied are believed to be representative of the organic-rich outer planetary system materials that seed all habitable zone planets with carbonaceous matter. The 200 micron size range is at the peak of the mass distribution where most of the 30,000 tons of extraterrestrial material is annually delivered to Earth. Some of the organic components of these small particles are retained inside the particles, others are destroyed by atmospheric entry heating and others are liberated into the atmosphere. We are studying all three of these processes and their effects on prebiotic evolution

    Donald Brownlee Donald Brownlee
    Project Investigator
    Monika Kress Monika Kress
    George Cody

    Graciela Matrajit

    Objective 1.1
    Models of formation and evolution of habitable planets

    Objective 3.1
    Sources of prebiotic materials and catalysts