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| programme = Mars rovers (NASA) | previous_mission = ''Sojourner'' | next_mission = ''Curiosity'' }} ''Opportunity'', also known as MER-B (Mars Exploration Rover – B) or MER-1, is a robotic rover active on the planet Mars since 2004.〔 Launched on July 7, 2003 as part of NASA's Mars Exploration Rover program, it landed in Meridiani Planum on January 25, 2004, three weeks after its twin ''Spirit'' (MER-A) touched down on the other side of the planet.〔 With a planned 90 sol duration of activity, ''Spirit'' functioned until getting stuck in 2009 and ceased communications in 2010, while ''Opportunity'' remains active as of 2015, having already exceeded its operating plan by (in Earth time). ''Opportunity'' has continued to move, gather scientific observations, and report back to Earth for over 45 times its designed lifespan. Mission highlights include the initial 90 sol mission, finding extramartian meteorites such as Heat Shield Rock (Meridiani Planum meteorite), and over two years studying Victoria crater. It survived dust-storms and reached Endeavour crater in 2011, which has been described as a "second landing site".〔 The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, California, manages the Mars Exploration Rover project for NASA's Science Mission Directorate in Washington, D.C.. == Objectives == The scientific objectives of the Mars Exploration Rover mission are to:〔 * Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation or hydrothermal activity. * Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites. * Determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, and cratering. * Perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit. * Search for iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates. * Characterize the mineralogy and textures of rocks and soils and determine the processes that created them. * Search for geological clues to the environmental conditions that existed when liquid water was present. * Assess whether those environments were conducive to life. During the next two decades, NASA will continue to conduct missions to address whether life ever arose on Mars. The search begins with determining whether the Martian environment was ever suitable for life. Life, as we understand it, requires water, so the history of water on Mars is critical to finding out if the Martian environment was ever conducive to life. Although the Mars Exploration Rovers do not have the ability to detect life directly, they are offering very important information on the habitability of the environment in the planet's history. 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「Opportunity (rover)」の詳細全文を読む スポンサード リンク
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