Japan Geoscience Union Meeting 2015

Presentation information


Symbol P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS21] Planetary Sciences

Sun. May 24, 2015 9:00 AM - 10:45 AM A02 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Kosuke Kurosawa(Planetary Exploration Research Center, Chiba Institute of Technology), Keiko Hamano(Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo), Chair:Keiko Hamano(Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo), Kosuke Kurosawa(Planetary Exploration Research Center, Chiba Institute of Technology)

9:00 AM - 9:15 AM

[PPS21-01] A way to establish a framework of Astrobiology

*Shigenori MARUYAMA1, Toshikazu EBISUZAKI2, Eizo NAKAMURA3 (1.Earth-Life Science Institute, Tokyo Institute of Technology, 2.RIKEN, 3.Institute for study of the Earth's interior, Okayama University)

One of an ultimate mysteries of Science is the existence of life in the Universe. In regard to this question, three ideas have been provided; (1) The Universe teems with life, (2) No other life other than Earth life, and (3) between 1 and 2. Also, we have two simple questions about life. (1) Is primitive life constantly emerging on present Earth? (2) Once whole life is killed, another new Earth life will emerge on the Earth? The answer to both questions is No.
Astrobiology is the academic field that can provide minimum conditions to bear life in the Universe, and also collateral conditions to make a planet to have civilization. Here we summarize such conditions to have life with civilization. To emerge life on the Earth, there are numerous kinds of conditions which are intricately interrelated. Here, we categorized such complex conditions into three groups. (1) Conditions to make life-sustainable planets derived from planetary formation theory. This category lists 19 conditions. For example, elliptical orbit is unacceptable condition for life. Even if f such planet is covered by liquid water, planet is to experience snowball for half the year, and for other half year water component turn to vapor due to red hot scorching environment like Venus. (2) Conditions to emerge and evolve life on the planet. This category includes 7 significant conditions which control the emergence and evolution of life. One of conditions is lifetime of carbon. Carbon is necessary component for life body, however the amount of carbon for life is decreasing through time. Carbon will be depleted in 1 billion years, indicating termination of life. (3) Conditions to have civilization on the planet. This category has 5 conditions. The most significant condition is brain development. Discontinuous upgrowth of brain differentiate human being from chimpanzee, and human is to establish civilization finally.