Formation, Alteration and Delivery of Exogenous High Molecular Weight Organic Compounds and Their Relevance to Origins of Life
24 de septiembre de 2010. 12:00h
Auditorio Centro de Astrobiologia CSIC-INTA
Instituto Nacional de Técnica Aeroespacial
Ctra de Ajalvir, km 4
28850 Torrejón de Ardoz, Madrid
Ponente: Pr. Kensei Kobayashi (Yokohama National University, Yokohama, Japan)
A wide variety of organic compounds have been detected in such extraterrestrial bodies as carbonaceous chondrites and comets.
Particularly, amino acids have been confirmed in extracts from carbonaceous chondrites and cometary dusts. It was suggested that these organics were formed in quite cold environments. We irradiated possible interstellar media, such as a frozen mixture of methanol, ammonia and water, with high-energy particles. Amino acid precursors with high molecular weights were detected in the irradiated products. Such complex amino acid precursors are much more stable than free amino acids against radiation, and heat. Seeds of homochirality could be formed after the complex amino acid precursors were altered by irradiation with circularly polarized UV light or polarized electrons.
The complex precursors of amino acids of interstellar origin could have been delivered to primitive Earth by meteorites, comets and interplanetary dusts (IDPs). It is suggested that IDPs brought much more organics than meteorites and comets. However, characteristics of organic compounds in IDPs are little known, since they have been collected only in terrestrial biosphere.
We are planning the Tanpopo Mission, where IDPs would be collected in aerogel equipped on the Exposure Facility of the International Space Station. In addition, amino acids and their relating compounds would be exposed to space environments to see their possible alteration processes.