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dec 31, 1993 - GPS建成
Description:
全球卫星定位系统,是美国国防部研制,美国太空军运营与维护的中距离圆型轨道卫星导航系统。
该系统由美国政府于1970年代开始进行研制,1989年2月14日第一颗GPS工作卫星发射成功,这一阶段的卫星称为BLOCK II和BLOCK IIA。此阶段宣告GPS系统进入工程建设状态。1993年底,现在的GPS网,即“21+3”GPS星座已经建成,今后将根据计划更换失效的卫星。
Added to timeline:
3.3.2战后演化
By
Frank Qiao
2 months ago
2
0
5504
Date:
dec 31, 1993
Now
~ 31 years ago
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