The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
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Volume 118, Issue 10
Displaying 1-12 of 12 articles from this issue
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SPECIAL ISSUE The role of geologists in Mars exploration
Review
  • The status of Mars exploration: the importance of terrestrial analogs and the role of geologists
    Goro Komatsu
    2012 Volume 118 Issue 10 Pages 597-605
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0004
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    Recent Martian exploration has been characterized by a dramatic improvement in the quality and quantity of data returned from Mars, as exemplified by high-resolution remote sensing data obtained by Martian orbiters, and outcrop data obtained by landers and rovers. A number of future Mars missions intend to target specific geological environments and will focus on astrobiological research. Other missions are even more ambitious and plan on returning samples to Earth for detailed laboratory-based analysis. The availability of abundant high-quality data is gradually opening opportunities for terrestrial geologists to investigate Martian geology by applying experiences derived from terrestrial analog sites. The geological environment of Mars resembles that of Earth, endorsing the validity of terrestrial analog studies to increase our understanding of geological processes on Mars. The majority of terrestrial analog sites have been located in cold and/or dry environments, such as the polar regions and continental deserts, with other analog sites being topically specific, including impact craters or volcanic fields. Although Asia, and Japan in particular, has to date not been considered an important area for planetary geology research, use of the wide variety of geological conditions present in this region as Martian analogs would be a significant addition to currently existing terrestrial analog studies.
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  • A proposal for rover geological exploration on Mars
    Noriyuki Namiki, Goro Komatsu, Tomohiro Usui, Seiji Sugita, Hideaki Mi ...
    2012 Volume 118 Issue 10 Pages 606-617
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0016
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    This paper outlines a new proposal for a Japanese-led geological rover-based exploration mission to Mars. Previous USA, former Soviet Union, and European missions have identified a wide diversity of Martian environments and a complex series of physical and chemical processes that operate or have operated on the Martian surface. Rover exploration, and associated chemical and isotopic analysis of geological material, allows us to understand and resolve the environmental evolution of the area around the landing site, and the proposed scientific target of the geological exploration part of this Martian mission will have a sedimentary or volcanic focus. Investigating sedimentary rocks will mean that this mission follows the road map advocated by NASA and European Space Agency (ESA) for the search for life on Mars. However, focusing this mission on volcanic rocks may open up a new field of research in Mars science. Although the focus has not been finalized, this future mission to Mars needs to be evaluated and supported by a broad community of Japanese Earth and planetary scientists.
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  • The comparative planetary geology of oceans, lakes and outflow channels on Mars
    Kazuhisa Goto, Goro Komatsu
    2012 Volume 118 Issue 10 Pages 618-631
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0009
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    Recently obtained high-resolution satellite imagery has enabled the detailed study of Martian geology and sedimentology. The identification of hydrological features, such as ocean, lakes, valley networks, and outflow channels, on the ancient surface of Mars is critically important to assess the history of water on the planet and to improve our understanding of the Martian climate record. Increasing evidence supports the presence of Noachian age lakes and valley networks, and Hesperian age oceans and outflow channels, although whether these features were formed by liquid water is still controversial. Clay minerals, such as phyllosilicates, have been identified in Noachian sediments within purported paleo-crater lakes, consistent with a fluvial and/or lacustrine origin. These rocks have been targeted by US and European space agencies as possible landing sites for future rover missions, with an outcrop in a hypothesized paleo-crater lake basin selected as the landing site for the next National Aeronautics and Space Administration (NASA) expedition to Mars. Increasing the research contribution of terrestrial geologists during future Martian exploration is key, because determining terrestrial analogues for features on Mars is critically important for the interpretation of Martian geological data.
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  • Reconstruction of atmospheric circulation system on Mars and Titan based on the eolian dune deposits
    Hitoshi Hasegawa
    2012 Volume 118 Issue 10 Pages 632-649
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0037
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    Eolian dunes are particularly suited for comprehensive planetary studies because they are generally present on terrestrial planets, including Earth, Mars, Venus, and Saturn's moon Titan. Although the distribution and orientation of eolian dunes are thought to record surface wind patterns and atmospheric circulation systems on planets and moons, the validity of this idea has not been fully tested. In this study, I compared general circulation model (GCM) reconstructions of the present-day atmospheric circulation systems on Mars and Titan with eolian dune orientations and dune field distributions. The reconstructed Martian surface wind patterns indicated by dune centroid azimuths (DCA) and dune slipface orientations (SF) are generally consistent with the predominant surface wind patterns during the northern Martian hemisphere winter. In addition, dune fields are concentrated in high-latitude areas adjacent to areas with strong winds associated with the descending part of the Hadley circulation cell. This indicates that the distribution of dune fields and dune orientation patterns provide a record of atmospheric circulation patterns on Mars. In comparison, dune orientation-based wind pattern reconstructions on Titan are not consistent with GCM-based atmospheric circulation patterns. This discrepancy is thought to relate to occasional fast westerly winds during equinoxes that dominate the eastward streamlining pattern of Titan's dunes. Nevertheless, dune field distributions are reflected in atmospheric circulation patterns on Titan. Therefore, although eolian dune orientations are not always consistent with prevailing planetary and lunar atmospheric circulation patterns, the distribution of dune fields generally does reflect these patterns.
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  • Aqueous environmental history of Mars revealed by mineralogy and geochemistry of outcrop exposures of sedimentary rocks
    Yasuhito Sekine
    2012 Volume 118 Issue 10 Pages 650-663
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0001
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    Recent high-resolution spectral images and in-situ observations have revealed more than 1000 outcrops of diverse aqueous mineral deposits on Mars. Layered deposits of phyllosilicates (and carbonates) have been found in the oldest terrains, suggesting active interactions between liquid water and basalts in the subsurface and/or on the surface of Mars at around 4.3–4.0 billion years ago. Hydrated sulfates and silica deposits formed by evaporation of acidic and oxidizing surface water under arid conditions have been found in the second period (∼4.0–3.2 billion years ago). After this period, liquid water does not seem to have played a major role for the formation of sediments on Mars. Here, we describe characteristics and possible origins of these aqueous sediments, review hypothesis for the causative mechanisms for Martian environmental change, and discuss new questions posed by the measurements.
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  • Methane on Mars
    Ryo Ishimaru, Goro Komatsu, Takafumi Matsui
    2012 Volume 118 Issue 10 Pages 664-674
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0008
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    Four research groups have independently reported the possible detection of methane in the Martian atmosphere using spacecraft and ground-based observations. Although each observation uses different instruments and has specific uncertainties, these observations produce similar results in terms of seasonal variations and global mean amounts of methane, implying that methane may be present in the current atmosphere of Mars. If methane is present on Mars, it is likely to be of geochemical and/or biological origin. A release of methane from the subsurface to the atmosphere may be associated with the formation of specific landforms, such as mud volcanoes, as observed on Earth. Although the presence of such landforms has been suggested on Mars, a causal link between these landforms and atmospheric methane has not been confirmed. We report that the observed lifetime of methane on Mars is shorter than that estimated from conventional photochemical models, with this short lifetime requiring rapid consumption of methane by a currently unknown process. This article summarizes observational results and our current understanding of physicochemical processes involved in the production, release, and consumption of Martian methane, and outlines future observation plans for documenting the abundance of methane on Mars.
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  • Life search projects of NASA/ESA and of MELOS project in Japan, on Mars
    Akihiko Yamagishi
    2012 Volume 118 Issue 10 Pages 675-682
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0017
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    To date, Mars-based exploration programs have attempted to determine whether water was ever present on Mars, with a more recent shift to research that aims to determine whether life ever existed on Mars. A joint NASA–ESA–MSL (National Aeronautics and Space Administration–European Space Agency–Mars Science Lab) program will determine whether life-related molecules are present on Mars using mass spectroscopy and tunable laser absorption spectroscopy. ESA-Russia ExoMars program will search for life-related molecules using an antibody-based molecule detection system.
    The Japan Astrobiology Mars Project (JAMP) section of the Japanese MELOS (Multiple Lander Orbiter Synergy) program is planning to search for cells within the uppermost several cm of Martian soil using a fluorescence microscope. The recent discovery of methane on Mars and the analysis of microbes on Earth have suggested the presence of methane-oxidizing microbes on the Martian surface, with a fluorescent pigment enabling the detection of cells of Martian origins that have significantly different characteristics from terrestrial-derived cells.
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Note
  • GIS analyses of Martian satellite imageries and topographic data
    Kazuhisa Goto, Goro Komatsu, Hitoshi Saito
    2012 Volume 118 Issue 10 Pages 683-688
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0010
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    A large amount of satellite imagery is now available for the surface of Mars; this imagery has spatial resolutions up to 25 cm/pixel, and a Digital Terrain Model (DTM) has been constructed to allow the analysis of Martian topography. These data are important for studies of geological and geomorphological processes on Mars, and may form the basis of future Mars exploration plans. Nevertheless, the procedures used to obtain these data and to project them using Geographic Information Systems (GIS) is significantly complicated, and this prevents many researchers from initiating geological or geomorphological research on Mars. Here, we introduce the procedures required to obtain Martian satellite imagery and topographic data, the methods used to project these data into GIS systems, and a simple Google Mars-based image analysis methodology. After projection, GIS-based data analytical approaches are similar to those commonly used for Earth-based data; consequently, geologists and geomorphologists who usually focus on terrestrial problems could easily shift their research focus to Mars, significantly improving the state of satellite imagery and topographic data-based Martian research and potentially contributing to future Mars missions.
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  • Experimental simulation of Martian surface environment
    Sohsuke Ohno
    2012 Volume 118 Issue 10 Pages 689-693
    Published: October 15, 2012
    Released on J-STAGE: February 20, 2013
    DOIhttps://doi.org/10.5575/geosoc.2012.0060
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    Recent Martian exploration missions have supplied detailed geological data from the surface of Mars. This has lead to an increase in the importance of Mars environmental simulation experiments as tools to interpret these newly acquired data. The recreation of the Martian surface atmosphere in environmental simulation chambers is essential for experimental studies to determine the geological and/or astrobiological processes that operate on Mars. Environmental simulators are also important to investigate and develop instruments for scientific observation during missions to Mars. Here, we introduce details of a general-purpose Mars environmental simulation chamber developed in the Planetary Exploration Research Center of the Chiba Institute of Technology (PERC/Chitech). The chamber can simulate the temperatures, pressures, and chemical compositions encountered within the Martian lower atmosphere.
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