著者

Ryodo HEMMI Hideaki MIYAMOTO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.63, no.4, pp.124-131, 2020 (Released:2020-07-04)

参考文献数

30

被引用文献数

5

---

Estimating the regolith properties of Phobos’ surface is of critical importance for the landing and performance of the Martian Moons eXploration (MMX) sample return mission. Regolith physical properties such as strength, regolith thickness, and the presence of regolith layers are related to morphologies of superposing impact craters. However, the accurate depths of Phobos’ sub-kilometer-diameter craters including irregularly shaped craters have not yet been fully characterized. Here, by using our high-resolution (20 m/pixel) digital elevation model of the nearside (or the sub-Mars side) of Phobos, we investigate the topographic profiles of the sub-kilometer craters. We confirm the presence of crater rims, and bowl-shaped, central-mound, and flat-floored crater geometries. The topography of one flat-floored crater is consistent with a boundary of regolith layers at a depth of ~160–180 meters. Morphometric measurements of 35 sub-kilometer craters show that their depth-to-diameter (d/D) ratios are in the range of 0.037 and 0.174 (mean value = 0.089, median value = 0.093). This suggests either a surface layer composed of rocky debris that effectively dissipates impact energy and causes a reduction in crater depth, or subsequent resurfacing events changed the original crater topography.

著者

Junichi HARUYAMA Isao KAWANO Takashi KUBOTA Masatsugu OTSUKI Hiroki KATO Toshihiko NISHIBORI Takahiro IWATA Yukio YAMAMOTO Yoshiaki ISHIHARA Aiko NAGAMATSU Kazuhito SHIMADA Toshiaki HASENAKA Tomokatsu MOROTA Masaki N. NISHINO Ko HASHIZUME Kazuto SAIKI Motomaro SHIRA Goro KOMATSU Nobuyuki HASEBE Hisayoshi SHIMIZU Hideaki MIYAMOTO Kensei KOBAYASHI Shinichi YOKOBORI Tatsuhiro MICHIKAMI Satoru YAMAMOTO Yasuhiro YOKOTA Hitoshi ARISUMI Genya ISHIGAMI Katsushi FURUTANI Yuichi MICHIKAWA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.14, no.ists30, pp.Pk_147-Pk_150, 2016 (Released:2017-02-14)

被引用文献数

1 5

---

We are planning to explore the caverns through the skylight holes on the Moon and Mars. The holes and their associated subsurface caverns are among the most important future exploration targets. The importance of the lunar and Martian holes and their associated caverns is categorized from two aspects: (1) fresh materials are easily observed and sampled there, and (2) the subsurface caverns provide a safe, quiet environment. The expectation of lunar and Martian hole and cavern exploration is increasing in Japan. We name the project as UZUME (Unprecedented Zipangu (Japan) Underworld of the Moon Exploration) whose name is after a Japanese mythology. The ultimate purpose of the UZUME project is to investigate how to expand human activity and survival in space and on extraterrestrial bodies.

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

---

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.