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Mars Atmosphere and Volatile EvolutioN Mission (MAVEN) is a space probe designed to study the Martian atmosphere while orbiting Mars. Mission goals include determining how the planet's atmosphere and water, presumed to have once been substantial, were lost over time.〔(New NASA Missions to Investigate How Mars Turned Hostile ). By Bill Steigerwald (November 18, 2012)〕〔(【引用サイトリンク】url=https://www.facebook.com/MAVEN2Mars )〕 MAVEN was successfully launched aboard an Atlas V launch vehicle at the beginning of the first launch window on November 18, 2013. Following the first engine burn of the Centaur second stage, the vehicle coasted in low Earth orbit for 27 minutes before a second Centaur burn of five minutes to insert it into a heliocentric Mars transit orbit. On September 22, 2014, MAVEN reached Mars and was inserted into an areocentric elliptic orbit by above the planet's surface. The principal investigator for the spacecraft is Bruce Jakosky of the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder.〔〔〔(【引用サイトリンク】title=NASA's MAVEN Spacecraft Makes Final Preparations For Mars )〕 On 5 November 2015, NASA announced that data from MAVEN shows that the erosion of Mars’ atmosphere increases significantly during solar storms. That loss of atmosphere to space likely played a key role in Mars' gradual shift from its carbon dioxide-dominated atmosphere - which had kept Mars relatively warm and allowed the planet to support liquid surface water - to the cold, arid planet we see today. This shift took place between about 4.2 to 3.7 billion years ago. ==History== The mission was spawned by NASA's Mars Scout Program, which, although discontinued in 2010, yielded Phoenix, MAVEN, and numerous missions' studies. Mars Scout missions target a cost of less than US$485 million, not including launch services, which cost approximately $187 million.〔(NASA Awards Launch Services Contract for Maven Mission ) (October 21, 2010)〕 The total project costs up to $671 million. On September 15, 2008, NASA announced that it had selected MAVEN to be the Mars Scout 2013 mission.〔 There was one other finalist and eight other proposals that were competing against MAVEN. The name is a deliberate use of the word ''maven'', "a person who has special knowledge or experience; an expert". On August 2, 2013, the MAVEN spacecraft arrived at Kennedy Space Center Florida to begin launch preparations. NASA scheduled the launch of MAVEN from the Cape Canaveral Air Force Station on November 18, 2013, using an Atlas V 401 rocket.〔(【引用サイトリンク】title=NASA Awards Launch Services Contract for MAVEN Mission )〕 The probe arrived in Mars orbit in September 2014, at approximately the same time as India's Mars Orbiter Mission. On October 1, 2013, only seven weeks before launch, a government shutdown caused suspension of work for two days and initially threatened to force a 26-month postponement of the mission. With the spacecraft nominally scheduled to launch on November 18, a delay beyond December 7 would have caused MAVEN to miss the launch window as Mars moved too far out of alignment with the Earth. However, two days later, a public announcement was made that NASA had deemed the 2013 MAVEN launch so essential to ensuring future communication with current NASA assets on Mars—the Opportunity and Curiosity rovers—that emergency funding was authorized to restart spacecraft processing in preparation for an on-time launch. On September 22, 2014, at approximately 2:24 UTC, MAVEN spacecraft entered orbit around Mars, completing an interplanetary journey of 10 months and 442 million miles (711 million kilometers). 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「MAVEN」の詳細全文を読む スポンサード リンク
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