Communication ability of satellite chain constellation _ satellite chain communication principle

Space exploration technology company 17 batch of star chains listed. Why does space exploration technology company make a star chain plan?

After completing the initial deployment of the satellite chain plan, Space Exploration Technology Company will continue to build the remaining satellites in the Ku/Ka band constellation consisting of 4,400 satellites, and the next step may start with adding the orbital satellite plane at higher latitudes. Space Exploration Technologies also has another constellation plan approved by the Federal Communications Commission, involving about 7,000 satellites in low-Earth orbit, which will communicate on V-band frequencies. (V-band frequency may be added to the original 4400 satellite in the future. )

In the past two months, in addition to applying for a larger second-generation satellite constellation, Space Exploration Technology Company also requested to modify the existing planned 4400 satellite constellation.

The above picture is a visual image of the orbital plane of Zhang Weixing. On the left, the planned deployment of the satellite chain initially containing 65,438+0,584 satellites is shown, and on the right, the complete constellation of 4,408 satellites in Ku/Ka band is displayed.

On April 17, 2020, Space Exploration Technology Company submitted a request to the Federal Communications Commission to further modify the satellite constellation layout in the satellite chain. In the revised version of 20 18, Space Exploration Technology Company reduced the overall height of the initial satellite network. Now, Space Exploration Technologies hopes to reduce the remaining Ku/Ka band satellites from the previous heights of 1 100 to 1300 km to a new height of 540 to 570 km. In addition, space exploration technology company also requires changing the inclination and structure of the orbital plane of these satellites.

In order to serve higher latitudes, Space Exploration Technology Company's current license includes multiple satellite groups with inclination angles of 70, 74 and 8 1 degree respectively. The new license application hopes to add another satellite group with an inclination of 70 degrees and a new satellite group with an inclination of 97.6 degrees. For those satellites launched into Sun Synchronous Orbit (SSO), this new group of satellites with an inclination of 97.6 degrees and a height of 560 kilometers will provide launch sharing opportunities.

In order to improve the coverage of polar services, Space Exploration Technology also applied to allow the communication between high-inclination satellites and high-latitude gateways to be conducted at a small angle of 5 degrees above the horizon, while the minimum angle at low latitudes is 25 degrees.

On May 26th, 2020, Space Exploration Technology Company submitted an application for the second generation satellite constellation to the Federal Communications Commission. The second generation constellation can accommodate up to 30,000 satellite chains, and the communication frequencies of these satellites will be Ku, Ka and E bands. It will be unrealistic to launch such a large number of satellites before the new Starship launch vehicle is put into use, and space exploration technology company has a large number of satellite system customers, but the advantage of this pre-planning is that if space exploration technology company wants to expand the deployment of other satellites in the future, they will be able to advance very easily. At this time, the application is submitted to coordinate the application for new satellites on certain frequencies before the deadline of the Federal Communications Commission, which does not necessarily mean that space exploration technology companies will immediately take corresponding launch deployment actions.