著者

長沼 毅 Takeshi NAGANUMA

出版者

創価大学人間学会

雑誌

創価人間学論集 (ISSN:18827942)

巻号頁・発行日

no.9, pp.51-79, 2016-03-16

著者

Takeshi Naganuma Hirohiko Uematsu

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.12, no.2, pp.126-130, 1998 (Released:2006-02-01)

参考文献数

25

被引用文献数

5 10

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Liquid water, underwater volcanoes and possibly life forms have been suggested to be present beneath the estimated 10 km-thick ice shell of Europa, the Jovian satellite J2. Europa's possible ocean is estimated to be 100-200 km deep. Despite the great depth of the Europa's ocean, hydrostatic pressure at the seafloor would be 130-260 MPa, corresponding to 13-26 km depth of a theoretical Earth's ocean. The hydrostatic pressure is not beyond the edge of existing deep-sea technology. Here we propose exploration of Europa's deep-sea by the use of current technologies, taking a symbolic example of a deep submergence vehicle Shinkai 6500 which dives to a depth of 6.5 km deep (50 km depth of Europa's ocean). Shinkai 6500 is embarkable in the payload bay of the Space Shuttles in terms of size and weight for the transportation to a Low Earth Orbit (LEO). Secondary boost is needed for interplanetary flight from the LEO.On-orbit assembly of the secondary booster is a technological challenge. The International Space Station (ISS) and ISS-related technologies will facilitate the secondary boost. Also, ice shell drilling is a challenge and is needed before the dive into Europa's ocean. These challenges should be overcome during a certain leading time for matured experience in the ISS operation.

著者

長沼 毅 Takeshi NAGANUMA

出版者

創価大学人間学会

雑誌

創価人間学論集 Collected papers of the humanities, Soka University (ISSN:18827942)

巻号頁・発行日

no.9, pp.51-79, 2016-03

著者

Akihiko Yamagishi Shin-ichi Yokobori Yoshitaka Yoshimura Masamichi Yamashita Hirofumi Hashimoto Takashi Kubota Hajime Yano Junichi Haruyama Makoto Tabata Kensei Kobayashi Hajime Honda Yuichi Utsumi Tsunemasa Saiki Takashi Itoh Atsuo Miyakawa Kenji Hamase Takeshi Naganuma Hajime Mita Kenichi Tonokura Sho Sasaki Hideaki Miyamoto

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.24, no.2, pp.67-82, 2010 (Released:2012-06-26)

参考文献数

114

被引用文献数

1 12

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Liquid water is considered to be critical for life. Gibbs free energy is another factor that is important to sustain life for long durations. Gibbs free energy is obtained by reactions between reductants and oxidants, or from any other non-equilibrium state of matter. As an example, aerobic organisms use carbohydrates and oxygen to obtain energy. Many types of chemoautotrophic mechanisms are known for this process as well. On the surface of Mars, methane and oxidative compounds such as ferric oxide, sulfate and perchloride, which could provide redox-derived Gibbs free energy, have been detected. Iron-dependent methane oxidizing bacteria have been found in marine environments on Earth. This finding suggests the possible presence of methane-oxidizing bacteria on the Mars surface, if the local thermal environment and other resources permit proliferation and metabolism of bacteria. Our project aims to search for methane-oxidizing microbes on the Mars surface. Martian soil will be sampled from a depth of about 5 - 10 cm below the surface, where organisms are expected to be protected from the harsh hyper-oxidative environment of the Mars surface. Small particles less than 0.1 mm or 1 mm will be sieved from the sample, before being transferred to the analysis section by a micro-actuator. The particles will be stained with a cocktail of fluorescent reagents, and examined by fluorescence microscopy. A combination of fluorescent dyes has been selected to identify life forms in samples. A membrane-specific dye or a combination of dyes will be used to detect membranes surrounding the "cell". An intercalating fluorescent dye such as SYBR Green will be used to detect genetic compounds such as DNA. A substrate dye that emits fluorescence upon cleavage by a catalytic reaction will be used to detect the catalytic activity of the "cell". A combination of staining reagents has been chosen based on the definition of life. A membrane separating a cell from the ambient environment may lead to identification of an "individual". DNA or genetic material is required for "replication" of the life form. Catalytic reactions carried out by enzymes drive "metabolism". This combination of strategies will also be useful for detecting pre-biotic organic material as well as remnants of ancient life. Hydrolysis of the polymers in the "cell" followed by HPLC or soft ionization MS for amino acid analysis will be effective for examining whether Martian life is identical to or different from terrestrial life. The number and type of the amino acids as well as their chirality will be analyzed to distinguish whether the polymers are contaminants from Earth.