At 4:11 am on March 30, 2016, China successfully launched the 22nd Beidou navigation satellite using the Long March 3A carrier rocket from the Xichang Satellite Launch Center. Currently, 60% of the launches have been completed.
According to the plan, by 2020, China will establish the Beidou Global Satellite Navigation and Positioning System, consisting of 5 geostationary orbit satellites and 30 non geostationary orbit satellites, providing high-precision, highly reliable positioning, navigation, and timing services covering the globe.
What is the significance of Beidou Navigation?
Satellite navigation has rich applications in agriculture, aviation, environment, maritime transportation, public safety and disaster relief, railways, space, surveying and mapping, and timing.
More importantly, in national defense, almost all fighter jets and missiles require navigation and positioning functions. Without location information, fighter jets may get lost and missiles may not know where to shoot. Taking China's Beidou as an example, in 2020, after Beidou achieved global satellite navigation function, it can increase China's combat effectiveness by 100-1000 times and combat cost-effectiveness ratio by 10-50 times, which will undoubtedly greatly enhance China's national defense capability.
Why does Beidou need 35 satellites, while GPS only needs 24?
GPS requires 24 satellites, which is just the most basic number. This number ensures that at least 4 satellites can be seen at any time in every part of the world, and the spatial three-dimensional coordinates and time variables can be solved through 4 equations. These 24 satellites are distributed in 6 orbital planes, with 4 satellites per orbital plane. The receiver of GPS system adopts passive positioning method (that is, the receiver does not need to send signals).
This goes back to the Beidou system itself. In addition to using passive receivers like GPS, Beidou also has two unique functions, which are using active receivers (the receiver actively sends signals to the satellite) and sending and receiving short messages (satellite SMS). Finally, there are 5 geosynchronous orbit satellites that are mainly required to be launched for both of these functions. Of course, these 5 stars also support passive positioning methods. The following picture is a photo of a geostationary orbit satellite. It can be seen that the satellite is really stationary, and the surrounding stars will deviate in the sky.
In fact, currently there are not 24 GPS satellites in operation, but 32 satellites; And GLONASS actually has 29. The extra satellites can not only serve as backups, but also increase system accuracy. For example, GPS can ensure that at least 9 satellites can be seen in most places, which can significantly improve positioning accuracy. Galileo is currently progressing slowly due to disputes among European countries, with only four (partially functional) satellites being deployed. When it will be effective in the future is still a matter of time. In contrast, China's deployment of four or five satellites can immediately provide positioning and special services, accelerating the speed of technology transformation into the market. This idea is still highly commendable. Therefore, Chinese people are still creative!
Why build our own navigation system?
GPS is the navigation system of the United States, which can turn off navigation services in certain regions as needed. If one day we offend the United States and they shut down GPS services, countless industries in our country will be greatly affected as a result. If you are driving in a place you have never been to before, guided by navigation, and suddenly the navigation is gone, what should you do?
In fact, after the GPS was built, the United States divided GPS signals into two categories: civilian standards and military standards.
Due to the fact that civilian standard positioning services do not require any authorization and can be used freely, the United States is concerned that enemies may use their own swords to attack them. Therefore, errors are artificially added to civilian signals to reduce accuracy, making the positioning accuracy around 100 meters; The military precision is below 10 meters.
It was not until after 2000 that the United States abolished interference with civilian signals. Because the United States has been able to disable GPS signals in any region during wartime through system updates, and this is also to maintain the global monopoly of GPS navigation systems.
So, after the comprehensive construction of China's Beidou global navigation system, it will benefit domestic manufacturers of navigation terminals and achieve overtaking on bends.
As a major country, we must have our own global satellite navigation system, which is Beidou! It is not only China's Beidou, but also the world's Beidou!
(Quoted from Sina website)