|
Galileo is the global navigation satellite system (GNSS) that is currently being created by the European Union (EU) and European Space Agency (ESA),〔(【引用サイトリンク】url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/243190/7199.pdf )〕 headquartered in Prague in the Czech Republic, with two ground operations centres, Oberpfaffenhofen near Munich in Germany and Fucino in Italy. The €5 billion project〔(【引用サイトリンク】url=http://www.dw.de/dw/article/0,,16304096,00.html )〕 is named after the Italian astronomer Galileo Galilei. One of the aims of Galileo is to provide an indigenous alternative high-precision positioning system upon which European nations can rely, independently from the Russian GLONASS and US GPS systems, in case they were disabled by their operators. The use of basic (low-precision) Galileo services will be free and open to everyone. The high-precision capabilities will be available for paying commercial users. Galileo is intended to provide horizontal and vertical position measurements within 1-metre precision, and better positioning services at high latitudes than other positioning systems. On 21 October 2011 the first two of four (Galileo #1 and #2) operational satellites were launched to validate the system. The next two (Galileo #3 and #4) followed on 12 October 2012, making it "possible to test Galileo end-to-end".〔 Once this In-Orbit Validation (IOV) phase was completed, additional satellites are being launched to reach Initial Operational Capability (IOC) around mid-decade. The first determination of a position relying on signals emitted only from Galileo satellites was achieved on 12 March 2013.〔(First position determined with Galileo ). Ec.europa.eu. Retrieved on 12 January 2014.〕 On 22 August 2014, two (Galileo #5 and #6) more satellites were launched from French Guiana〔http://www.bbc.com/news/science-environment-28860851〕 but were injected into an incorrect orbit.〔(Retrieved on 23 August 2014. )〕 Analysis indicated that the third stage of the Soyuz launch vehicle, the Fregat space tug, failed to circularize the satellites' orbit correctly, resulting in a semi-minor axis less than desired and a 5° inclination error.〔(Details of wrong orbit insertion. Retrieved on 23 August 2014. )〕 These orbits have now been corrected (December 2014 and March 2015) at the cost of reduced propellant, shortening the life-span of the satellites to 12 years' operation.〔(Retrieved on 26 June 2015. )〕〔(Retrieved on 26 June 2015. )〕 On 27 March 2015 the next two (Galileo #7 and #8) satellites were launched successfully from Guiana Space Centre using a Soyuz four stage launcher. Using the same Soyuz launcher and launchpad, satellites number 9 and 10 were launched successfully on 11 September 2015.〔(【引用サイトリンク】 publisher = European Space Agency )〕 Galileo is planned to provide a unique global search and rescue (SAR) function. Satellites will be equipped with a transponder which will relay distress signals from the user's transmitter to the Rescue Co-ordination Centre, which will then initiate a rescue operation. At the same time, the system is projected to provide a signal to the users, informing them that their situation has been detected and help is on the way. This latter feature is new and is considered a major upgrade compared to the existing GPS and GLONASS navigation systems, which do not provide feedback to the user. Tests in February 2014 found that for Galileo's search and rescue function, operating as part of the existing International Cospas-Sarsat Programme, 77% of simulated distress locations can be pinpointed within 2 km, and 95% within 5 km.〔(Space Daily )〕 Galileo will start offering first services from 2016. Full completion of the 30-satellite Galileo system (24 operational and 6 active spares) is expected by 2020.〔(Launch of first 2 operational Galileo IOV Satellites ). Ec.europa.eu (21 October 2011). Retrieved on 29 October 2011.〕 ==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「Galileo (satellite navigation)」の詳細全文を読む スポンサード リンク
|