单选题
China is to contribute to a new global satellite navigation system being developed by European nations. The Galileo satellite system (51) a more accurate civilian alternative to the Global Positioning System (GPS), operated by the US military. China will provide 230m Euros (USD 259m) in (52) and will cooperate with technical, manufacturing and market development." China will help Galileo to (53) the major world infrastructure (基础设施)for the growing market for location services," said Loyola de Palacio, EU transport commissioner.
A new center that will coordinate co-operation was also announced (54) the European Commission, the European Space Agency (ESA) and the Chinese Ministry of Science and Technology not long (55) . The China-Europe Global Navigation Satellite System Technical Training and Cooperation Center will be (56) at Beijing University. China has a substantial satellite launch industry and could potentially help launch the Galileo satellites.
The US has claimed that Galileo could interfere (57) the US ability to downgrade (降级) the GPS service during military conflicts. European officials say this is unfounded and counter that US opposition (58) the commercial challenge Galileo would present to GPS. Galileo will be precise to within a meter, while the civilian GPS service is accurate to around 10 meters.
The Galileo satellite constellation (卫星群集) will (59) 27 operational and three reserve satellites orbiting the Earth at an altitude of 23,600 km. The satellites will be strung along three medium-Earth orbits at 56 degrees inclination to the equator and will provide global coverage. The system should be operational by 2008 and the entire project is expected to (60) around 3.2 billion Euros (USD 3.6 billion).
The European Commission has said Galileo will primarily be used for transportation technology, scientific research, land management and disaster monitoring. Galileo will provide two signals; a standard civilian one and an encrypted (编码) , wide-band signal (61) the Public Regulated Service (PRS). This second signal is designed to withstand localized jamming(干扰)and will be used by police and military services in Europe. European Commission (62) have said China will not be given access to the PRS.
The first Galileo satellite is scheduled to launch late in 2004. Clocks on board the (63) will be synchronized (使同步) through 20 ground sensors stations, two command centers and 15 uplink (向上传输) stations. Receivers on the ground will use time signals from the satellites to precisely calculate their (64) . A "search and rescue" function will also (65) distress signals be relayed through the constellation of satellites.