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In the summer of 1965, the first close-up pictures from Mars revealed a cratered desert with no signs of water.〔(【引用サイトリンク】title=Mariner 4: First Spacecraft to Mars )〕〔(【引用サイトリンク】title=Blast from the past: Mariner 4's images of Mars | The Planetary Society )〕〔Snyder, C., V. Moroz. 1992. Spacecraft exploration of Mars. In Kieffer, H., B. Jakosky, C. Snyder, M. Matthews, (eds). 1992. Mars. University of Arizona Press. Tucson.〕 However, over the decades, as more parts of the planet were imaged with better cameras on more sophisticated satellites, Mars showed evidence of past river valleys, lakes, and ice in glaciers and in the ground.〔(【引用サイトリンク】title=What is the evidence for water on Mars? )〕 It was discovered that the climate of Mars displays huge changes over geologic time because its axis is not stabilized by a large moon like our Earth.〔Madeleine, J. et al. 2007. Mars: A proposed climatic scenario for northern mid-latitude glaciation. Lunar Planet. Sci. 38. Abstract 1778.〕〔Madeleine, J. et al. 2009. Amazonian northern mid-latitude glaciation on Mars: A proposed climate scenario. Icarus: 203. 300-405.〕〔Mischna, M. et al. 2003. On the orbital forcing of Martian water and CO2 cycles: A general circulation model study with simplified volatile schemes. J. Geophys. Res. 108. (E6). 5062.〕 Also, some researchers maintain that water could exist for periods of time due to geothermal effects or asteroid impacts.〔Newsom, H. 2010. Heated Lakes on Mars. In Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY.〕〔Abramov, O., D. Kring. 2005. Impact-induced hydrothermal activity on early Mars. Journal of Geophys. Res. 110 (20). Doi:10.1029?2005je002453.〕〔Newsom, H. 1980. Hydrothermal alteration of impact melt sheets with implications for Mars. Icarus: 44 (1), 207-216.〕〔Newsom, H., et al. 1996. Impact crater lakes on Mars. J. Geophys. Res. 101 E6, 14951-9144955.〕〔McKay, C., Davis, W. 1991. Duration of liquid water habitats on early Mars. Icarus: 90 (2), 214-221.〕 Besides seeing features that were signs of past water, researchers found other types of evidence for past water. Minerals detected in many locations needed water to form.〔Bibring, J., et al. 2006. Global mineralogical and aqueous history derived from OMEGA observations. Science: 312, 400-404.〕〔Murchie, S., et al. 2008. First results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), LPSC XXXIX abstract 1472.〕〔Zolotov, M., M. Mironenko. 2008. Formation and fate of phyllosilicates on the surface of Mars: Geochemical modeling of aqueous weathering. LPSC XXXIX, Abstract 3365.〕〔Carr, M., J. Head. In Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY〕〔Gendrin, A. et al. 2005. Sulfates in Martian Layered Terrains: The OMEGA/Mars express view. Science: 307, 1587–1591.〕 An instrument in the Mars Odyssey, an orbiting spacecraft, mapped the distribution of water in the near surface.〔(【引用サイトリンク】title=Evidence of Vast Quantities of Water Ice on Mars )〕〔(【引用サイトリンク】title=Lunar & Planetary Lab at The University of Arizona )〕〔(【引用サイトリンク】title=Ground ice on Mars is patchy and variable | Mars Odyssey Mission THEMIS )〕 When the Phoenix spacecraft fired its rockets to land in the far north, ice was exposed.〔(【引用サイトリンク】title=Ice Under the Lander? | Phoenix on Mars )〕 When water enters a large body of water, like a lake, a delta may form. Many craters and other depressions on Mars show deltas that resemble those on Earth. In addition, if a lake lies in a depression, channels entering it will all stop at the same height. Such an arrangement is visible around places on Mars that are supposed to have contained large bodies of water—including around a possible ocean in the North. Lake formation has been proposed by various researchers for quite some time.〔De Hon, R. 1992. Martian lake basins and lacustrine plains. Earth Moon Planets: 56, 95-122.〕〔Cabrol, N., E. Grin. 1999. Distribution, classification, and ages of martian impact crater lakes. Icarus: 142, 160-172.〕〔Cabrol, N., E. Grin. 2001. The evolution of lacustrine environments on Mars: Is Mars only hydrologically dormant. Icarus: 149, 291-328.〕 One study found 205 possible closed-basin lakes in craters on Mars. The basins have an inlet valley that cuts the crater rim and flows into the basin, but they have no visible outlet valley. The total volume of the basins equals water to 1.2 meters in depth spread evenly over Martian surface. However, this amount is a small fraction of the modern water ice stores on Mars.〔Goudge, T., K. Aureli, J. Head, C. Fassett, J. Mustard. 2015. Classification and analysis of candidate impact crater-hosted closed-basin lakes on Mars. Icarus: 260, 346-367.〕 Another study, found 210 open-basin lakes. These were lakes with both an inlet and an outlet; hence water must have entered the basin, and reached the height of the outlet. Some of these lakes had volumes similar to Earth's Caspian Sea, Black Sea, and Lake Baikal.〔Fassett, C. J. Head. 2008. Valley network-fed, open-basin lakes on Mars: Distribution and implications for Noachian surface and subsurface hydrology. Icarus: 198, 37-56.〕 Moreover, some basins on Mars are part of long chains of lakes.〔Cabrol, N., E. Grin. 1999. Distribution, classification, and ages of martian impact crater lakes. Icarus: 142, 160-172.〕 The Naktong/Scamander/Mamers Valles lake-chain system is about 4500 Km long and a drainage area similar to the Earth's Missouri-Mississippi River's.〔Irwin, R. et al. 2005. An intense terminal epoch of widespread fluvial activity on early Mars. 2. Increased runoff and paleolake development. J. Geophys. Res. (Planet: 10, doi: 10.1029?2005JE002460.E12S15〕 Another, the Samara/Himera Vallis system is 1800 Km long.〔Fassett, C., J. Head. 2008. Valley network-fed, open-basin lakes on Mars: Distribution and implications for Noachian surface and subsurface hydrology. Icarus: 198, 37-56.〕 Many of the long chains of lakes are found in the Margaritifer Sinus quadrangle.〔Grant, J. T. Parker. 2002. Drainage evolution in the Margaritifer Sinus region, Mars. J. Geophys. Res. 107. doi:10.1029/2001JE001678. 5066.〕 Some of the lakes appear to have had a high volume as compared to their drainage area; hence, it is believed that some of the water was groundwater. Further evidence is the existence of knobby material on the basin floors. These knobs can be formed when large amounts of water left the ground.〔Head, J., S. Pratt. 2001. Closed chaos basins on Mars: Evidence for regional groundwater drawdown and collapse. Lunar Planet. Sci. XXXII. Abstract 1774.〕〔Irwin, R., et al. 2002. A large paleolake basin at the head of Ma'adim Vallis, Mars. Science: 296, 2209-2212.〕〔Irwin, R., et al. 2004. Geomorphology of Ma'adim Vallis, Mars, and associated paleolake basins. J. Geophys. Res. 109. doi:10.1029/2004JE002287. E12009.〕 This article will describe some of the places that could have held large lakes. Perhaps, the lakes held water long enough for life to form. ==Images of possible deltas== Image:Delta in Margaritifer Sinus.jpg|Possible delta in Margaritifer Sinus quadrangle as seen by THEMIS. Image:Distributary fan-delta.jpg|Probable delta in Eberswalde Crater that lies to the NE of Holden Crater, as seen by Mars Global Surveyor. Image in Margaritifer Sinus quadrangle. Image:Delta in Lunae Palus.jpg|Delta in Lunae Palus quadrangle, as seen by THEMIS. Image:Delta as seen by HiRISE.jpg|Delta that fills a crater in Lunae Palus quadrangle, as seen by HiRISE. |Image:605555-PIA15097-JezeroCrater-Delta.jpg|Jezero crater delta - chemical alteration by water (hi-res) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lakes on Mars」の詳細全文を読む スポンサード リンク
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