たんぽぽ（蒲公英，dandelion）は綿毛のついた種子を風に乗せて頒布し，その生息域を広げる多年草である．我々は，この名前のもと，国際宇宙ステーション-JEM（日本実験棟）上での微生物と生命材料となり得る有機化合物の天体間の移動の可能性の検討と微小隕石の検出および解析実験を提案する．我々は，超低密度エアロゲルを用いることで，微小隕石やその他の微粒子を捕集することが可能であると考えている．低軌道上で超低密度エアロゲルを一定期間曝露することで宇宙空間で微粒子を捕集する．エアロゲル表面と衝突トラックの顕微観察の後，エアロゲルの様々な解析を行う．衝突トラックの詳細な検討により，国際宇宙ステーション周辺のデブリのサイズと速度が明らかにできると期待される．エアロゲル中に残存した粒子に関して，鉱物学的，有機化学的，及び微生物学的な検討を行う．一方，宇宙環境下での微生物の生存可能性について検討するため，微生物を直接宇宙空間に曝露する実験も行う．同様に，宇宙環境下での有機化合物の変性の可能性を検討するため，有機化合物の宇宙空間への直接曝露実験も行う．これらの実験を行うための装置はすべて受動的な装置であり，そのための装置の基本構造，装置回収後の解析法も，既に確立されている．

  A great number of experiments have been done to examine possible prebiotic formation of bioorganic compounds such as amino acids in possible primitive environments. There are two scenario of prebiotic formation of bioorganic compounds: An endogenous formation scenario and an exogenous formation scenario. The latter scenario was supported by the facts that a wide variety of organic compounds were detected in meteorites and comets. It is now suggested that organic compounds in extraterrestrial bodies were originally formed in extremely cold environments such as in molecular clouds. Laboratory experiments showed that complex precursors of amino acids could be formed from simulated interstellar media by irradiation with high-energy particles. It was suggested that such extraterrestrial organic compounds were delivered mainly by cosmic dusts. We have, however, very limited information on organic compounds in cosmic dusts since they are captured within terrestrial environments. We proposed a novel astrobiology mission “Tanpopo” by utilizing the international space station. In the mission, cosmic dusts will be collected with ultra-low-density aerogel, and organic compounds in them will be analyzed. In the mission, organic compounds simulating extraterrestrial organics will be directly exposed to solar ultraviolet light and cosmic rays at the same time to study the fate of organic compounds in cosmic dusts near the Earth orbit.

  Analyses of organic compounds in the extraterrestrial materials, e. g. carbonaceous chondrites, micrometeorites, and cometary dust, are important for the study of origins of life on the Earth, since the terrestrial living organisms are formed by highly organized organic compounds and, organic compounds and their source materials should be transported into the Earth from the outside of the Earth. To avoid the contaminants from the terrestrial organisms is the most important for organic analyses of the extraterrestrial materials. Therefore, intact micrometeoroids captured on the exposure facility of the “Kibo” module at the International Space Station by “TANPOPO” mission are suitable for the astrobiological studies concerning with origins of life. In this review, organic analyses of extraterrestrial materials are summarized and tasks for the analyses of organic compounds in the sub-mm sized micrometeoroids, especially captured particles in the “TANPOPO” mission, are described.