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A Mars rover is an automated motor vehicle that propels itself across the surface of the planet Mars upon arrival. Rovers have several advantages over stationary landers: they examine more territory, and they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. There have been four successful robotically operated Mars rovers. The Jet Propulsion Laboratory managed the Mars Pathfinder mission and its now inactive ''Sojourner'' rover. It currently manages the Mars Exploration Rover mission's active ''Opportunity'' rover and inactive ''Spirit'', and, as part of the Mars Science Laboratory mission, the ''Curiosity'' rover. On January 24, 2014, NASA reported that current studies on the planet Mars by the ''Curiosity'' and ''Opportunity'' rovers will now be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic, and/or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may have been habitable. The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on the planet Mars is now a primary NASA objective.〔 ==Synopsis== Several rovers have been sent to Mars: * ''Mars 2'', ''Prop-M'' rover, 1971, ''Mars 2'' landing failed taking Prop-M with it. The ''Mars 2'' and ''3'' spacecraft from the USSR had identical 4.5 kg ''Prop-M'' rovers. They were to move on skis while connected to the landers with cables.〔 〕 * ''Mars 3'', ''Prop-M'' rover, 1971, lost when ''Mars 3'' lander stopped communicating about 20 seconds after landing.〔 * ''Sojourner'' rover, Mars Pathfinder, landed successfully on July 4, 1997. Communications were lost on September 27, 1997. * ''Beagle 2'', ''Planetary Undersurface Tool'', lost with Beagle 2 on deployment from Mars Express in 2003.〔 A compressed spring mechanism was designed to allow movement across the surface at a rate of 1 cm per 5 seconds〔(NSSDC – Beagle 2 ). NASA〕 and to burrow into the ground and collect a subsurface sample in a cavity in its tip. * ''Spirit'' (MER-A), Mars Exploration Rover, launched on June 10, 2003 at 13:58:47 EDT〔(【引用サイトリンク】 url = http://marsrovers.jpl.nasa.gov/mission/launch_e.html )〕 and landed successfully on January 4, 2004. Nearly 6 years after the original mission limit, Spirit had covered a total distance of but its wheels became trapped in sand. Around January 26, 2010, NASA conceded defeat in its efforts to free the rover and stated that it would now function as a stationary science platform. The last communication received from the rover was on March 22, 2010, and NASA ceased attempts to re-establish communication on May 25, 2011. * ''Opportunity'' (MER-B), Mars Exploration Rover, launched on July 7, 2003 at 23:18:15 EDT〔 and landed successfully on January 25, 2004. ''Opportunity'' surpassed the previous record for longevity of a surface mission to Mars as of May 20, 2010 and surpassed the previous record for distance traveled off-Earth as of July 28, 2014 by covering a total distance of .〔('Greeley Haven' is Winter Workplace for Mars Rover )〕 ''Opportunity'' is still operational and mobile as of , . * ''Curiosity'', Mars Science Laboratory (MSL), by NASA, was launched November 26, 2011 at 10:02 EST〔(【引用サイトリンク】 url = http://www.nasa.gov/mission_pages/msl/launch/index.html )〕 and landed in the Aeolis Palus plain near Aeolis Mons (informally "Mount Sharp") in Gale Crater on August 6, 2012, 05:31 UTC. Curiosity Rover is still going as of , . 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「Mars rover」の詳細全文を読む スポンサード リンク
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