|
}} ''MESSENGER'' (a backronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging, and a reference to the Roman mythological messenger, Mercury) was a NASA robotic spacecraft that orbited the planet Mercury between 2011 and 2015. The spacecraft was launched aboard a Delta II rocket in August 2004 to study Mercury's chemical composition, geology, and magnetic field. The instruments carried by ''MESSENGER'' were used on a complex series of flybys – the spacecraft flew by Earth once, Venus twice, and Mercury itself three times, allowing it to decelerate relative to Mercury using minimal fuel. ''MESSENGER'' became the second mission after Mariner 10's 1975 flyby to reach Mercury during its first flyby of the planet in January 2008. ''MESSENGER'' entered orbit around Mercury on March 18, 2011, becoming the first spacecraft to do so.〔 It successfully completed its primary mission in 2012.〔 Following two mission extensions, the ''MESSENGER'' spacecraft used the last of its maneuvering propellant and deorbited as planned, impacting the surface of Mercury on April 30, 2015. == Mission overview == ''MESSENGERs formal data collection mission began on April 4, 2011.〔(SmithsonianNationalAirandSpaceMuseum 2011-05-24 Exploring Mercury by Spacecraft: The MESSENGER Mission )〕 The primary mission was completed on March 17, 2012, having collected close to 100,000 images. ''MESSENGER'' achieved 100% mapping of Mercury on March 6, 2013, and completed its first year-long extended mission on March 17, 2013. ''MESSENGER''s second extended mission lasted for over two years, but as its low orbit degraded, it required reboosts to avoid impact. It conducted its final reboost burns on October 24, 2014, and January 21, 2015, before crashing into Mercury on April 30, 2015. During its stay in Mercury orbit, ''MESSENGER'' 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「MESSENGER」の詳細全文を読む スポンサード リンク
|