Astrophysical and Astrochemical Insights into the Origin of Life

Ehrenfreund, P ; Becker, L ; Blank, J ; Brucato, J ; Colangeli, L ; Derenne, S ; Despois, D ; Dutrey, A ; Fraaije, H ; Irvine, W ; Lazcano, A ; Owen, T ; Robert, F

Lawrence Livermore National Laboratory

关键词: Comets;    Origin;    99 General And Miscellaneous//Mathematics, Computing, And Information Science;    Genetics;    Chaos Theory;   

DOI  :  10.2172/15013483
RP-ID  :  UCRL-ID-148252
RP-ID  :  W-7405-ENG-48
RP-ID  :  15013483

美国|英语

来源: UNT Digital Library

【 摘 要 】

Nucleosynthesis of heavy elements such as carbon in stars allowed the formation of organic molecules in space, which appear to be widespread in our Galaxy. The physical and chemical conditions - including density, temperature, ultraviolet radiation and energetic particles - determine reaction pathways and the complexity of organic molecules in different space environments. Dense interstellar clouds are the birth sites of stars of all masses and their planetary systems. During the protostellar collapse, gaseous and solid interstellar organic molecules are integrated into protostellar disks from which planets and smaller solar system bodies form. After the formation of the planets in our own solar system, 4.6 billion years ago, all of them, including the Earth, were subjected to frequent impacts for several hundred million years. First indications for life on Earth are dated 3.8-3.5 billion years ago. That life arose very shortly after this heavy bombardment phase raises many questions. A prebiotic non-reducing atmosphere predicts that building blocks of macromolecules--such as amino acids, sugars, purines and pyrimidines were not formed in abundance. A part of the prebiotic organic content of the early Earth could have been delivered by asteroids, comets and smaller fragments such as meteorites and interplanetary dust particles (IDPs). Current experimental research investigating the origin of life is focused on the spontaneous formation of stable polymers out of monomers. However, understanding the spontaneous formation of structure is not enough to understand the formation of He. The introduction and evolution of information and complexity is essential to our definition of life. The formation of complexity and the means to distribute and store information is currently investigated in a number of theoretical frameworks; such as evolving algorithms, chaos theory, and modem evolution theory. In this article we review the physical and chemical processes that form and shape organic matter in space. In particular we discuss the chemical pathways of organic matter in the interstellar medium, their evolution in protoplanetary disks and their integration into solar system material. Furthermore we investigate the role of impacts and the delivery of organic matter to the prebiotic Earth. Processes that may have assembled prebiotic molecules to produce the first genetic material and ideas about the formation of complexity in chemical networks are discussed.