Viva Origino
Online ISSN : 1346-6933
Print ISSN : 0910-4003
47 巻, 3 号
  • 鈴木 大輝
    2019 年 47 巻 3 号 p. 3-
    発行日: 2019年
    公開日: 2021/11/16
    ジャーナル フリー

      There was huge progress in the studies of interstellar chemistry both in the formation processes of molecules and the survey observations of them. In the meteorites, detections of complex organic molecules including amino acids and nucleus basis suggest the possibility of their incorporation into the first chemical evolution toward the first life on the primordial Earth.

      Such molecules would have delivered to the early Earth by the interstellar dust particles, comets, and asteroids. The previous simulations of the cometary bombardment suggested that some kinds of amino acids may survive the high-temperature environment and are supplied to the early Earth without the thermal pyrolysis (Pierazzo & Chyba 1999). Based on these results, Ehrenfreund (2002) estimated that the amount of organic molecules delivered from the Universe to the early Earth was 1000 times higher than those produced by the terrestrial formation mechanisms such as the lightning if 10% of organic molecules survive during the impacts.

      Therefore the surviving rate of molecules after the comets/asteroids bombardment is a key to connect the chemistry in the Universe and on the early Earth. Many works are left in this research. For example, in the previous simulations, the effect of the impact obliqueness was considered using the results of other works. This computation method is not good enough, and the surviving rate of molecules should be re-investigated with the latest simulations. Besides, even if organic molecules are decomposed during the impact, new important organic molecules might have been built after cooling of the materials. The outgassing process from the comets/asteroids is also intriguing since the terrestrial energy sources would synthesize the organic molecules if CH4 or CO were supplied from the impact body to the ancient atmosphere. The understanding of the comets/asteroids bombardment would be a key to reveal the first chemical evolution of materials toward the first life.