The Possible interplanetary transfer of microbes; Assessing the viability of spp. under the ISS environmental conditions for performing exposure experiments of microbes in the Tanpopo mission

Kawaguchi, Yuko*; Yang, Y.*; Kawashiri, Narutoshi*; Shiraishi, Keisuke*; Narumi, Issey*; Sato, Katsuya; Hashimoto, Hirofumi*; Nakagawa, Kazumichi*; Tanigawa, Yoshiaki*; Momoki, Yohei*; Tanabe, Maiko*; Sugino, Tomohiro*; Takahashi, Yuta*; Shimizu, Yasuyuki*; Yoshida, Satoshi*; Kobayashi, Kensei*; Yokobori, Shinichi*; Yamagishi, Akihiko*

To investigate the interplanetary transfer of life, numerous exposure experiments have been carried out on various microbes in space since the 1960s. In the Tanpopo mission, we have proposed to carry out experiments on capture and space exposure of microbes at the Exposure Facility of the Japanese Experimental Module of the International Space Station (ISS). Microbial candidates for the exposure experiments in space include spp.: , , and . We have examined the survivability of spp. under the environmental conditions in ISS orbit (i.e., long exposure to heavy-ion beams, temperature cycles, vacuum and UV irradiation). We concluded that aggregated deinococcal cells will survive the yearlong exposure experiments. We propose that the microbial cells aggregate as an ark for the interplanetary transfer of microbes, and named it "Massapanspermia".