Two more Beidou satellites are sent into orbit on Dec 16, 2019. XINHUA
Rome wasn’t built in a day.
Nearly two decades have passed since China launched the first Beidou satellite in 2000. In that time, more Beidou satellites were sent into orbit, forming the Beidou Navigation Satellite System. In late 2012, it began providing positioning, navigation, timing and messaging services to people in China and other parts of the Asia-Pacific region.
At the end of 2018, BDS started to provide global services. “This marks Beidou’s entry into a ‘global era’ from its ‘regional era’,” BDS Spokesperson Ran Chengqi said at a news conference.
Now with two more Beidou satellites launched on Dec 16, 2019, BDS has 53 satellites in orbit – more than US government’s Global Positioning System (GPS), which has 31 active satellites. That launch means the core of Beidou’s third-generation network is now in place. It’s expected to greatly improve the system’s ability to serve users worldwide.
2019年12月16日，随着两颗北斗卫星再次成功发射，北斗卫星导航系统在轨运行的卫星数量上升至53颗 —— 多于美国政府只有31颗在轨卫星的全球定位系统。此次发射标志着北斗三号全球系统核心星座部署完成，有望极大增强该系统服务全球用户的能力。
Although a satellite-based navigation system needs only 24 satellites to run properly, having 53 allows for better coverage.
This is how it works: A signal receiver on Earth – your smartphone, for example – measures its distance from at least three satellites by recording the amount of time it takes to receive their signals. Then it can calculate its location. With so many satellites, BDS can provide a more accurate calculation. While GPS calculates locations to within a few meters, BDS reduces the error to centimeters. This high-precision service is useful for land surveying, mapping, agriculture and automated driving.
卫星导航系统的工作原理是这样的：地球上的信号接收器 —— 比如说，你的智能手机 —— 通过记录接收卫星信号所需的时间，测量出自身与至少三颗卫星之间的距离。然后再据此计算出所处的地理位置。拥有众多卫星的北斗卫星导航系统能够提供更精准的计算。全球定位系统地理位置的计算误差在几米之内，而北斗卫星导航系统能将误差缩小至厘米范围。这种高精度的服务可用于土地测量、地图绘制、农业以及自动驾驶等。
China is willing to share BDS with the world. According to Ran, BDS products have been exported to more than 120 countries and regions. “The Beidou system will always adhere to the development concept of ‘China’s Beidou, the world’s Beidou, and the first-class Beidou’, serving the world and benefiting mankind,” Ran told reporters after the latest launch.
He added that future plans call for a smarter and more accessible system with Beidou at its core, to come online by 2035.
By then, we can probably say that Rome has finally been built.