There are many highlights! Yiwang Constellation was built after many twists and turns

On March 26, with the successful launch of 36 satellites by the Indian LVM3 rocket, OneWeb completed the final networking deployment of the first phase of its low-orbit Internet constellation, and is about to form a global service capability. The construction of the OneWeb constellation has gone through multiple tests such as technology, politics, and economy. According to the design, what are the technical highlights of this constellation? What functions and uses does it have? How is it expected to continue to develop in the future to play a greater role?

The construction process was full of twists and turns

Due to the development of the Internet traffic economy in recent years, many Internet giants have set their sights on billions of potential users. Greg Wyler, founder of OneWeb, also has the same dream. He founded OneWeb in London, England, with the initial goal of building a low-latency, low-orbit broadband Internet constellation composed of hundreds of satellites, declaring that the goal is to "enable everyone on Earth to access the Internet seamlessly anywhere."

Indian rocket launches OneWeb satellite (Photo credit: Indian Space Research Organization) Thanks to the company's founders' familiarity with the communications industry, the company's initial development was quite smooth. In 2014, the predecessor of OneWeb proposed a plan to build a constellation of 648 small satellites, and then obtained the required frequency and orbit resources from another company on the verge of bankruptcy and registered with the International Telecommunication Union. In January 2016, OneWeb and European Airbus Defense and Space Company jointly established OneWeb Satellite Company to start satellite production. On June 25, 2017, OneWeb obtained the US low-orbit satellite communication network operating license and was allowed to provide services in the United States.

From the perspective of all aspects of the Internet satellite project, OneWeb was the most comprehensive and ahead of its peers at the time. It was precisely because the project had been prepared in advance in terms of supply chain, spectrum, launch license, approval and space debris mitigation that investors had considerable confidence.

Since then, OneWeb has encountered setbacks such as rising satellite costs and overall project costs, obstacles in applying for frequency bands in many countries, and difficulty in project financing. The launch of the first batch of satellites has also been delayed several times. However, with the launch of the first batch of six prototype satellites by a Russian-made Soyuz rocket operated by Arianespace at the Kourou Space Launch Center in French Guiana on February 27, 2019, OneWeb's prospects have once again become optimistic.

However, due to the impact of the COVID-19 pandemic, its capital chain was broken and OneWeb was forced to file for bankruptcy protection in March 2020. Subsequently, the British government and Indian giants reached an acquisition agreement with OneWeb on July 3, injecting US$500 million each. In addition, with generous contributions from investors such as SoftBank Group, Hughes Network Systems, and Eutelsat, OneWeb Constellation finally received sufficient financial support.

To make matters worse, after the outbreak of the Russian-Ukrainian conflict in 2022, the agreement signed by OneWeb and Arianespace to launch satellites using Russian rockets was forced to be terminated due to Western sanctions. At that time, OneWeb's constellation had only completed 66% of the satellite deployment work in the first phase, and only opened connection services in the higher latitudes of the northern hemisphere.

Fortunately, OneWeb took remedial action soon after the suspension of launches and reached new launch agreements with SpaceX of the United States and NewSpace of India. Since then, the Falcon 9 rocket of the United States and the Indian rocket have carried out 3 and 2 launch missions respectively, and finally completed the deployment of the first phase of the OneWeb constellation.

Technical highlights cannot be ignored

With the initial deployment of the constellation completed, OneWeb has become the second operator of a giant Internet constellation with global service capabilities. Due to its unique design, OneWeb's constellation has technical highlights and certain advantages that cannot be ignored compared to the Starlink constellation.

OneWeb satellites are about to be loaded into the rocket fairing (Photo credit: Indian Space Research Organization) As we all know, the first phase of the OneWeb constellation uses 648 satellites deployed in low-Earth orbit to achieve service area coverage and provide global broadband interconnection and Internet of Things services. These satellites include 588 duty satellites and 60 backup satellites, distributed in 18 orbital planes at an altitude of 1,200 kilometers and an inclination of 87.9 degrees, with an interval of 9 degrees between adjacent orbital planes.

These satellites have good performance, with a single satellite launch mass of 147.5 kg. The payload includes 2 telemetry antennas, 2 Ku-band antennas and 2 Ka-band antennas, which are used for user communications and gateway communications respectively. The communication capacity reaches 8 Gigabits per second, which means that 1GB of data is expected to be transmitted per second. By using solar panels and lithium-ion batteries to supply the energy storage system, the satellite's on-orbit service life is about 5 years. When a OneNet satellite is operating over a non-equatorial area, a single satellite can generate 16 Ku-band beams to achieve multiple coverage. Each satellite covers a range of 1080×1080 kilometers, ensuring that each user is within the "line of sight" of at least one satellite. When providing services, the connection time between a single satellite and a ground user terminal does not exceed 2.5 minutes, and multiple satellites can relay to complete communication services.

It is not difficult to see from these descriptions that the OneWeb constellation has abandoned the intersatellite link design and has deployed a total of 44 gateway stations around the world. After the user terminal makes a service request, the OneWeb satellite receives the request through the Ku-band antenna, and then forwards it to the available gateway station through the Ka-band antenna. The gateway station submits the request to the network server. After returning the data, the OneWeb satellite transmits the service data to the user terminal through the Ku-band antenna.

The OneWeb satellites over the equator are specially designed and applied with "progressive tilt" technology to prevent frequency interference with geosynchronous orbit satellites. Simply put, under the previous technical conditions, when the OneWeb satellites over the equator happened to run below the geosynchronous orbit satellites, the signal of the OneWeb satellites was poor and the satellite service had to be shut down; but the "progressive tilt" technology can gradually tilt the satellite signal beam by changing the pitch attitude of the non-vertical interference "window" satellites. When the vertical interference "window" satellites shut down their services, customers in the equatorial sub-satellite point area can still receive services.

In terms of satellite manufacturing, OneNet Constellation has a lot of highlights. Drawing on the experience of the automotive manufacturing industry, the company has built the world's first advanced satellite mass manufacturing plant and the world's first satellite production line. Through integrated design, production, assembly and testing, it has achieved a production rate of 40 satellites per month. In production, the company has adopted a large number of automation measures such as collaborative robots and self-guided transporters, which has enabled the component testing process to be ahead of component delivery, and has greatly improved production efficiency by using digital testing.

After a large number of satellites are launched, space debris mitigation measures are essential. OneWeb satellites use xenon ion thrusters. After entering the initial orbit hundreds of kilometers high, they will rely on the electric propulsion system to carry out orbit raising, which takes about 3 months to finally enter the orbit at an altitude of 1,200 kilometers. After the satellite fails, with the help of the reliable xenon electric propulsion system, it is expected that the orbit perigee will be changed to less than 200 kilometers within 5 years, and finally fall into the atmosphere and burn up.

Global expansion and striving for excellence

After the first phase of OneWeb’s constellation is deployed, the next step is application promotion. In July 2022, OneWeb and Eutelsat announced a merger plan, which will allow the OneWeb constellation in low Earth orbit to work closely with large video data relay/broadband satellite platforms in geostationary orbit.

This is considered a major consolidation in the commercial satellite communications market. Founded in 1977, Eutelsat operates 36 geosynchronous orbit communications satellites, which are generally larger and more powerful than low-Earth orbit broadband satellites and provide services to a large number of customers in a fixed geographic area. However, their signal coverage at the Earth's poles is limited, and communication delays are also worthy of attention. Now, the "strong alliance" with the low-Earth orbit constellation will surely complement each other and achieve better comprehensive benefits.

OneWeb provides broadband internet services to corporate and government customers in various countries through distributors. This will help expand the service market, especially after Indian companies take a stake in it. It is reported that OneWeb has signed a six-year broadband distribution deal with Hughes Communications India Private Limited, a joint venture between Indian company Bharti Airtel and US company Hughes Network Systems. Hughes Network Systems is also a minority shareholder of OneWeb and is building gateways for it in India and other places.

Commercial promotion and hardware construction are almost going hand in hand. After the completion of the first phase of the constellation, OneWeb is committed to the larger second phase of the constellation, and ultimately plans to deploy 6,372 satellites in low-Earth orbit at an altitude of 1,200 kilometers and 1,280 satellites in medium orbit at an altitude of 8,500 kilometers. Some analysts believe that the second phase of the OneWeb constellation is expected to have a stronger European flavor, and the resources of Eutelsat will provide financial support for it.

In addition, the second-generation OneWeb satellites will be manufactured primarily in the UK and are planned to be launched using the reusable Terran series rockets starting in 2025.

As the trend of commercial satellites "joining the military" rises, the British government is also considering expanding the OneWeb constellation as a replacement for the military-grade global navigation satellite system. Due to Brexit, the British military cannot guarantee the smooth use of the military-grade encrypted signals of the European Galileo satellite navigation system in the future. The OneWeb constellation provides a possible backup plan for it. It can be said that OneWeb's business will gradually get involved in areas of strategic significance to the UK, helping it to "charge" towards the forefront of the aerospace field. (Author: Yu Yuanhang)