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''Gaia'' is a space observatory of the European Space Agency (ESA) designed for astrometry. The mission aims to construct a 3D space catalog of approximately 1 billion astronomical objects, mainly stars〔(【引用サイトリンク】title=We have already installed the eye of 'Gaia' with a billion pixels to study the Milky Way )〕 (approximately 1% of the Milky Way population)〔(【引用サイトリンク】title=ESA Gaia spacecraft summary )〕 brighter than 20 G magnitude, where G is the ''Gaia magnitude'' passband between about 400 and 1000 nanometres light wavelengths. Additionally ''Gaia'' is expected to detect thousands to tens of thousands of Jupiter-sized planets beyond the Solar System,〔(【引用サイトリンク】url=http://www.esa.int/Our_Activities/Space_Science/Gaia/Science_objectives )〕 500,000 quasars and tens of thousands of new asteroids and comets within the Solar System.〔(【引用サイトリンク】url=http://www.cam.ac.uk/research/features/gaias-mission-solving-the-celestial-puzzle )〕〔(【引用サイトリンク】url=http://www.satnews.com/story.php?number=155387954 )〕〔(【引用サイトリンク】url=http://www.thehindubusinessline.com/news/science/gaia-space-telescope-to-detect-killer-asteroids/article5257693.com )〕 The spacecraft will monitor each of its target stars about 70 times over a period of five years. ''Gaia'' will create a precise three-dimensional map of astronomical objects throughout the Milky Way and map their motions, which encode the origin and subsequent evolution of the Milky Way. The spectrophotometric measurements will provide the detailed physical properties of all stars observed, characterizing their luminosity, effective temperature, gravity and elemental composition. This massive stellar census will provide the basic observational data to tackle a wide range of important questions related to the origin, structure, and evolutionary history of our galaxy. Successor to the ''Hipparcos'' mission, the telescope is part of ESA's Horizon 2000+ long-term scientific program. ''Gaia'' was launched on 19 December 2013 by Arianespace using a Soyuz ST-B/Fregat-MT rocket flying from Kourou in French Guiana.〔(【引用サイトリンク】url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=51116 )〕 The spacecraft currently operates in a Lissajous orbit around the Sun–Earth L2 Lagrangian point. == History == The ''Gaia'' space telescope has its roots in ESA's Hipparcos mission (1989–1993). Its mission was proposed in October 1993 by Lennart Lindegren (Lund University, Sweden) and Michael Perryman (ESA) in response to a call for proposals for ESA's Horizon Plus long-term scientific programme. It was adopted by ESA's Science Programme Committee as cornerstone mission number 6 on 13 October 2000, and the B2 phase of the project was authorised on 9 February 2006, with EADS Astrium taking responsibility for the hardware. The name "Gaia" was originally derived as an acronym for Global Astrometric Interferometer for Astrophysics. This reflected the optical technique of interferometry that was originally planned for use on the spacecraft. While the working method evolved during studies and the acronym is no longer applicable, the name ''Gaia'' remained to provide continuity with the project. The total cost of the mission is around €740 million (~ $1 billion), including the manufacture, launch and ground operations.〔(【引用サイトリンク】publisher=Theguardian )〕 ''Gaia'' was completed two years behind schedule and 16% above its initial budget, mostly due to the difficulties encountered in polishing ''Gaia'' ten mirrors and assembling and testing the focal plane camera system, as well as other issues.〔Svitak, Amy, Galaxy charter, Aviation Week and Space Technology, 2 September 2013, p.30〕 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「Gaia (spacecraft)」の詳細全文を読む スポンサード リンク
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