title: Investigation of the Interplanetary Transfer of Microbes in the Tanpopo Mission at the Exposed Facility of the International Space Station.
abstract: The Tanpopo mission will address fundamental questions on the origin of terrestrial life. The main goal is to test the panspermia hypothesis. Panspermia is a long-standing hypothesis suggesting the interplanetary transport of microbes. Another goal is to test the possible origin of organic compounds carried from space by micrometeorites before the terrestrial origin of life. To investigate the panspermia hypothesis and the possible space origin of organic compounds, we performed space experiments at the Exposed Facility (EF) of the Japanese Experiment Module (JEM) of the International Space Station (ISS). The mission was named Tanpopo, which in Japanese means dandelion. We capture any orbiting microparticles, such as micrometeorites, space debris, and terrestrial particles carrying microbes as bioaerosols, by using blocks of silica aerogel. We also test the survival of microbial species and organic compounds in the space environment for up to 3 years. The goal of this review is to introduce an overview of the Tanpopo mission with particular emphasis on the investigation of the interplanetary transfer of microbes. The Exposed Experiment Handrail Attachment Mechanism with aluminum Capture Panels (CPs) and Exposure Panels (EPs) was exposed on the EF-JEM on May 26, 2015. The first CPs and EPs will be returned to the ground in mid-2016. Possible escape of terrestrial microbes from Earth to space will be evaluated by investigating the upper limit of terrestrial microbes by the capture experiment. Possible mechanisms for transfer of microbes over the stratosphere and an investigation of the effect of the microbial cell-aggregate size on survivability in space will also be discussed.
  
  
  
  Panspermia-Astrobiology-Low-Earth orbit. Astrobiology 16, 363-376.
authors.affiliation: 1 Institute of Space and Astronautical Science , Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Japan .|2 School of Life Sciences, Tokyo University of Pharmacy and Life Sciences , Hachioji, Tokyo, Japan .
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawaguchi
authors.affiliation: 2 School of Life Sciences, Tokyo University of Pharmacy and Life Sciences , Hachioji, Tokyo, Japan .
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Yokobori
authors.affiliation: 1 Institute of Space and Astronautical Science , Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Japan .
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: 1 Institute of Space and Astronautical Science , Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Japan .
authors.forename: Hajime
authors.initials: H
authors.lastname: Yano
authors.affiliation: 3 Graduate School of Science, Chiba University , Chiba-shi, Japan .
authors.forename: Makoto
authors.initials: M
authors.lastname: Tabata
authors.affiliation: 3 Graduate School of Science, Chiba University , Chiba-shi, Japan .
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kawai
authors.affiliation: 2 School of Life Sciences, Tokyo University of Pharmacy and Life Sciences , Hachioji, Tokyo, Japan .
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamagishi
mesh_terms: D000531:Altitude; D001419:Bacteria / Q000378:metabolism*; D005658:Fungi / Q000502:physiology*; D016083:Planets; D013026:Space Flight