中国：北斗衛星､打上げに成功：A total of 54 satellites（BeiDou-2 ､BeiDou-3 ）(動画）：
China launches penultimate BeiDou navigation satellite：
中国发射倒数第二的北斗导航卫星
中国：北斗衛星
BeiDouの計画は、全地球測位、ナビゲーション、タイミング（PNT）システム稼働を､行うためのものです。
今回、最後から2番目の衛星打ち上げに､成功しました。
3月9日､中国南西部/西昌衛星センターで､打ち上げを実施。
The BeiDou system：
has been developed in three phases.
The first phase
was largely experimental with the first satellite placed in orbit in October 2000.
The second phase
provided a regional navigation system and was declared operational in 2012.
The third phase
provides global coverage, with the launch of the final satellite in the network planned for May.
A total of 54 BeiDou-2 and BeiDou-3 satellites have been launched since 2007,
although these include some platforms that provide a degree of redundancy and others used to fully develop the BeiDou-3 system.
Jane’s 360
https://www.janes.com/article/94842/china-launches-penultimate-beidou-navigation-satellite
China’s new navigation system is nearly complete with penultimate Beidou satellite launch | Space
https://www.space.com/amp/china-long-march-3b-rocket-launches-54th-beidou-satellite.html