Satellite mega-constellations : all you need to know and news

satellite constellations

Satellite mega-constellations : big opportunities and big worries

– News of June 6, 2019 –

In recent months, a Soyuz rocket and a Falcon 9 have put into orbit the first satellites of two huge constellations, OneWeb and Starlink who are racing to set up satellite internet services. They will soon be joined by Amazon and possibly other companies. Together, these constellations could bring together up to 18,000 satellites. This is more than ten times the number of satellites currently in operation and twice as many satellites launched since Sputnik.

The investments are huge, the potential turnover also

Such ambition requires considerable effort. SpaceX estimates that setting up their service will cost them $ 10 billion. OneWeb has already raised $ 3 billion from major telecommunications companies. These huge investments are justified by the profit that these companies hope to draw.

By creating a true global internet, these companies hope to reach more than 3 billion people who do not yet have access to the internet. Even if they charge only a few euros a month, this will generate incredible revenue. SpaceX wants to use this turnover to make concrete the colonization of the planet Mars. The technological and commercial battle that has just started could therefore have repercussions far beyond the blue planet.

Satellite mega-constellations will finally bring internet everywhere on Earth

Satellite internet has been created a long time ago. If you have a satellite antenna and an adequate package, a satellite in geostationary orbit will give you a bit of bandwidth. These packages are often capped and seen as a last resort. If neither fiber nor ADSL is available in your area, you can try this method. In France, you will probably be served by a satellite of the constellation Eutelsat or ASTRA, whatever your operator. However, get ready for big bills, high latency and not always very stable service. The satellites that feed these offers have other services to provide. They reserve most of their bandwidth on satellite TV and a multitude of other services.

The constellations of SpaceX and OneWeb have been designed with the internet as a primary use, which involves completely different satellites, orbits and communication means. These satellites are not placed in geostationary orbit and they abandon the idea of ​​a single satellite of several tons that feeds an entire continent. These new satellite constellations make the choice to deploy a very large number of small satellites placed in low orbit.

Their number should make possible to provide internet to a large public at a high speed and at any time. They are designed to operate between 500 km and 1500 km altitude, which divides the access time by 70 compared to a satellite in geostationary orbit. This can not compete with the fiber in terms of latency, but it’s still a huge improvement.

With 12,000 satellites, Starlink will be the largest satellite mega-constellation

SpaceX goes further than any of its competitors by requesting launch authorizations for 12,000 satellites to launch the Starlink constellation. SpaceX also makes the most launches. A single rocket Falcon 9 put in orbit 60 satellites on May 24, 2019. At this rate, the service could begin to be marketed after only six other shots.

Despite their small size, the satellites imagined for Starlink are technological jewels. They weigh 227 kg, are flat and have a single solar panel. On the other side are located their four communication antennas. The first satellites use only the Ku band, which is the frequencies that are usually used for satellite television. In the future, the constellation will also pass through the Ka band which has the advantage of being able to be received with very small antennas of 20 cm in diameter. Communications must go through a protocol simpler than IPv6 and will be encrypted all along the line.

Satellite mega-constellations will not provide a high internet speed… before the arrival of lasers

Finally, these satellites must be able to communicate with each other to transmit a signal from one end of the planet to the other. They must therefore use ground stations to receive a signal, to travel through the channels of the conventional internet to another station close to the end user. The signal will then make a new round trip through space before reaching the targeted antenna. The infrastructure and latency should be huge.

In the long term, inter-satellite communications must therefore be carried out by laser. Satellites will communicate directly in very high bandwidth without going through the ground, which will greatly improve latency issues, but it will still need ground stations to make the link with the conventional internet.

The propulsion of satellites in the Starlink constellation uses krypton Hall effect motors, a cheaper alternative to xenon. SpaceX says these satellites will have an automatic space debris avoidance system.

Space debris, sky observation… The satellite mega-constellations raise many concerns

Now that Starlink and OneWeb have launched their first satellites, we need to study the consequences of such projects. Placing 18,000 satellites in orbit may alert those already concerned about space pollution. Obviously, we first think about the risk of collision and a possible Kessler syndrome. A first impact is enough to destroy a satellite and create a large number of space debris, which then becomes a danger for the remaining satellites. A chain reaction is then likely to take place. We have already seen some accidents with the satellites currently in orbit. Doubling or tripling their number increases the risk of collision.

To address this problem, international standards have been created. Satellites at the end of their life must desorbit in less than 25 years. Given their number, it is crucial that those of Starlink and OneWeb respect these guidelines. Fortunately, both companies have made such announcements. Satellites that reach the end of their life must use whatever remains of propellant to lower their orbit and burn in the atmosphere. Ideally, they will be destroyed less than a year after the end of their mission.

We can still imagine many scenarios that could complicate things. What will happen if, for example, the propulsion of the spacecraft is broken down ? On 18,000 satellites this may happen more than once.

Another problem was not necessarily foreseen by these companies, light pollution. The first 60 satellites of Starlink are very visible in the sky. The International Astronomical Union has expressed its concern about the impact that these satellite mega-constellations will have on astronomical observations made from the ground. Imagine tens of thousands of small luminous dots moving in the sky. We also know that some migratory birds, frogs or even seals use the stars to orient themselves.

Radio pollution is another area of ​​concern for astronomers. Thousands of satellites will be trading with millions or billions of ground antennas continuously. Radio telescopes already have difficulties in ignoring all human communications, how to continue studying cosmic phenomena in the middle of all this noise ? Starlink seems ready to take the necessary steps to solve the problem. Elon Musk announced on Twitter that his teams would try to reduce the albedo of the satellites of the constellation, but it is not sure that it is enough.

Satellite mega-constellations will provide internet access to billions of people

Satellite internet can cause concern, but it is also a great source of hope. There are still very large inequalities in people’s access to the internet. Bringing fiber or even ADSL to remote corners of the world requires investment in infrastructure that some countries simply can not afford. If they manage to offer sufficiently low prices, OneWeb and Starlink could allow 3 billion people to connect to the rest of the planet.

This could have important consequences for some internet spaces. For example, the French-speaking internet could grow by several million new users. Some French-speaking African countries are among the least well connected in the world. In the most developed countries, the countryside is not always well served. Satellite internet could be a reliable and fast way to access the internet thanks to Starlink or OneWeb. The internet in planes will become the norm, and maybe it will be possible to subscribe global packages, which work as well in Europe as in South America or in the middle of the Pacific.

Starlink and OneWeb satellite constellations could be operational within a year or two, but it will probably take a decade for them to ramp up. Amazon, Facebook and other companies may come up with alternative services. More than ever, this service will make enter space in people’s everyday lives.

Image by Thales Alenia Space

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