The Tanpopo experiment was the first Japanese astrobiology mission on board the International Space Station. It included exposure experiments of microbes and organic compounds as well as a capture experiment of hypervelocity impacting microparticles. We deployed three Exposure Panels, each consisting of 20 Exposure Units that contained microbes, organic compounds, an alanine UV dosimeter or an ionizing radiation dosimeter. The three Exposure Panels were situated on the zenith face of the Exposed Experiment Handrail Attachment Mechanism (ExHAM) that was pointing in zenith direction toward space, which was attached on a handrail of the Japanese Experiment Module (Kibo) Exposed Facility (JEM-EF) outside the International Space Station. The three Exposure Panels were one by one retrieved and returned to the ground after approximately 1, 2, and 3 years of exposure to the space environment. Capture Panels, each of which contained one or two blocks of amorphous silica aerogel, were exposed to collect hypervelocity impact microparticles. Possible captured particles may include micrometeoroids, human-made orbital debris, and natural terrestrial particles. Each year, Capture Panels containing from 11 to 12 aerogel blocks were attached to the three faces of the ExHAM (pointing to zenith, ram, and port); they remained in place for about 1 year and were then returned to the laboratory. This process was repeated three times, in total, during 2015–2018. Additional exposure of a Capture Panel facing ram was conducted between 2018 and 2019. Once the aerogel blocks were returned to the laboratory, they were encapsulated in dedicated transparent plastic cases and optically inspected by a specially designed microscopic system. Once located and recorded, hypervelocity impact signatures were excavated one by one and distributed for further detailed analyses. The apparatus, operation, and environmental factors of all the Tanpopo experiments are summarized in this article.

中文翻译：

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Tanpopo 的四年运行：国际空间站 JEM 暴露设施的天体生物学暴露和微流星体捕获实验

Tanpopo 实验是国际空间站上的第一个日本天体生物学任务。它包括微生物和有机化合物的暴露实验以及超高速撞击微粒的捕获实验。我们部署了三个曝光面板，每个面板由 20 个曝光单元组成，其中包含微生物、有机化合物、丙氨酸紫外线剂量计或电离辐射剂量计。三个曝光面板位于外露实验扶手连接装置 (ExHAM) 的天顶面上，该装置在天顶方向指向太空，该装置连接在日本实验模块 (Kibo) 外露设施 (JEM-EF) 的扶手上国际空间站外。三块曝光板在大约1、2、2、2、3、3、3、4、3、3、3、5后，被一一取回并返回地面。和 3 年暴露于太空环境。每个包含一个或两个无定形二氧化硅气凝胶块的捕获面板被暴露以收集超高速撞击微粒。可能捕获的粒子可能包括微流星体、人造轨道碎片和天然陆地粒子。每年，将包含 11 到 12 个气凝胶块的捕获面板连接到 ExHAM 的三个面（指向天顶、柱塞和端口）；它们在原地放置了大约 1 年，然后被送回实验室。在 2015-2018 年间，这一过程总共重复了 3 次。在 2018 年至 2019 年期间，对面向 ram 的捕获面板进行了额外曝光。一旦气凝胶块返回实验室，它们被封装在专用的透明塑料外壳中，并由专门设计的显微系统进行光学检查。一旦定位并记录下来，超高速撞击特征就会被一一挖掘并分发以进行进一步的详细分析。本文总结了所有 Tanpopo 实验的设备、操作和环境因素。