BEIJING, Jan. 18 -- China leads development of satellite atomic clocks, researchers said Thursday.
BeiDou navigation satellites sent to orbit last week are fitted with the latest generation of rubidium and hydrogen atomic clocks developed by the Second Academy of China Aerospace Science and Industry Corp.
Compared with the previous generation, the new clocks are smaller, lighter, perform much better and are among the world's best, Chinese scientists said.
Atomic clocks use vibrations of atoms to measure time. An accurate and ultra-stable set of atomic clocks is essential for global navigation satellite systems that require a high degree of precision.
BeiDou aims to rival the GPS of the United States, Russia's GLONASS and the European Union's Galileo as an alternative global satellite navigation system. It intends to cover Belt and Road countries by the end of 2018 and operate globally by around 2020 with a 35-satellite constellation.
2014人教新目标英语八下unit 10《I’ve had this bike for three years》课件3
2014人教新目标英语八下unit 3《Could you please clean your room》section a 2b课本听力素材(mp3)
人教版英语八下Unit 9《Have you ever been to a museum》(Section A 2d)课文朗读
人教版英语八下Unit 9《Have you ever been to a museum》课件包2
人教版英语八下Unit 9《Have you ever been to a museum》(Section A 3a)课文朗读
2014人教新目标英语八下unit 1《What’s the matter》section b 1a-2e课件
2014人教新目标英语八下unit 10《I’ve had this bike for three years》课件4
2014人教新目标英语八下unit 1《What’s the matter》words单词听力朗读素材(mp3)
2014人教新目标英语八下unit 1《What’s the matter》period 2课件
2014人教新目标英语八下unit 1《What’s the matter》section b 1c课本听力素材(mp3)
2014人教新目标英语八下unit 3《Could you please clean your room》section a 1b课本听力素材(mp3)
2014人教新目标英语八下unit 10《I’ve had this bike for three years》课件1
2014人教新目标英语八下unit 1《What’s the matter》section b 1b课本听力素材(mp3)
2014人教新目标英语八下unit 10《I’ve had this bike for three years》课件2
2014人教新目标英语八下unit 10《I’ve had this bike for three years》words单词听力朗读素材(mp3)
2014人教新目标英语八下unit 1《What’s the matter》section a 1a-1c课件
人教版英语八下Unit 9《Have you ever been to a museum》(Section A-2)课件
2014人教新目标英语八下unit 1《What’s the matter》section a 1a-2d课件
2014人教新目标英语八下unit 1《What’s the matter》section a 2b课本听力素材(mp3)
2014人教新目标英语八下unit 1《What’s the matter》period 3课件
2014人教新目标英语八下unit 1《What’s the matter》section a 3a-4c(含grammar focus)课件
2014人教新目标英语八下unit 3《Could you please clean your room》period 5课件
2014人教新目标英语八下unit 1《What’s the matter》section a 1b课本听力素材(mp3)
2014人教新目标英语八下unit 1《What’s the matter》section a 2d课本听力素材(mp3)
人教版英语八下Unit 9《Have you ever been to a museum》(Section A 1b)课文朗读
2014人教新目标英语八下unit 10《I’ve had this bike for three years》section b 1c课本听力素材(mp3)
2014人教新目标英语八下unit 1《What’s the matter》period 1课件
2014人教新目标英语八下unit 10《I’ve had this bike for three years》section b1课件
2014人教新目标英语八下unit 1《What’s the matter》section a 3a课本听力素材(mp3)
2014人教新目标英语八下unit 3《Could you please clean your room》section a 1a-2d课件
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