What are satellite mega-constellations?

During the last decades, we have lived an epoch in which many satellites have been put to orbit around the Earth. Many of them work in group, such as the GPS satellites, of which there are 31 orbiting the Earth. However, new projects want to put hundreds, and even thousands, of satellites orbiting the Earth. It is at this moment in which we talk of satellite mega-constellations.

In the first place, we will start seeing what a constellation of satellites is. They are groups of similar satellites (we could say identical), that are situated in the same orbit, and dedicated to achieve a global scale service. The concept isn’t new, and there are very well known satellite constellations that have been offering us service for decades, either of global positioning, such as the GPS (with 31 satellites), or of mobile telephony, as for example Iridium (with 66 satellites).

It is at that moment when, based on this idea, consisting of a small number of satellites, projects are born that want to put into operation thousands of satellites in orbit. From here comes the denomination of “mega-constellation”, so that we can distinguish them from the previous ones.

The purpose of mega-constellations

In the world in which we live, the Internet is an increasingly necessary tool, and unfortunately, there are many places on the planet where there it is not present. The principal objective of mega-constellations is to offer Internet access through all the Earth.

The big number of satellites should make it possible to provide internet to a big public, at high speed, and any moment. In this way, if the companies that offer this service put sufficiently low prices, they could allow more than 3 000 million people that currently do not have access to the internet, to connect with the rest of the planet.

Big investments, big gains

A so big ambition requires a considerable effort, and a big investment. SpaceX, with its mega-constellation of satellites Starlink, estimates that start up its mega-constellation will cost about 10 000 million dollars. These big investments would be recompensed by the enormous benefits that SpaceX, and other enterprises, hope to make.

If they were to provide internet to the vast majority of the human population, even if companies were to charge a small amount of money, this would generate enormous incomes.

Starlink, the biggest of all mega-constellations

The enterprise of Elon Musk, SpaceX, sent towards space, the 24th of May 2019, the first 60 satellites of its big project. Each launch puts into orbit 60 additional satellites, and by now it has already put hundreds of satellites in orbit. However, it is already allowed the deployment of 12 000 Starlink satellites, and SpaceX has already done the petition to increase to the colossal number of 42 000.

Despite their small size, the satellites of Starlink are true technological gems. They weigh 227 kilograms, they are flat and they only have one solar panel. The Starlinks are situated in the inferior section of the low Earth orbit, from where they will offer us satellite internet in many parts of the planet, where the optic fibre and antenna don’t arrive. In this way, they hope to offer a quick Internet where the conventional tools don’t arrive, as in deserts, jungles, or in planes.

Moreover, they have a small propulsion system that lets them change their orbit, and in case of being in disuse, they could use them to enter the atmosphere and disintegrate in the process. Like this, the quantity of space junk orbiting the Earth wouldn’t increase as much.

Other enterprises

SpaceX isn’t the only one that wants to construct a mega-constellation. Other companies are putting their own satellites in orbit and others have still got to do it. After Starlink, the project that is the most advanced is the one of OneWeb, which also wants to send thousands of satellites into orbit. Soon Amazon, Facebook, Link, Telesat, and many other companies, will also start sending them.

It is estimated that, in one decade, the number of satellites around the Earth will be, at a minimum, 50 000. In comparison, nowadays there are 20 000 objects orbiting the Earth, of which only 2000 are active satellites. Only with Starlink’s satellites, it will triplicate to 60 000 the number of objects orbiting the Earth.

The problems of mega-constellations

Despite being a very ambitious and extraordinary project, mega-constellations have also some harmful effects:

  • On one hand, the photographies of stars, galaxies and other bodies, require to capture of many light of the photographed object. For this reason, the observatories are situated far away from cities, where there isn’t light pollution. But when mega-constellations will be in operation, if one of the satellites passed through a determined zone at the moment of taking a photo of this type, it would provoke a light trail that would leave the photo unusable. As much as we made the satellites darker, the telescopes will always end up seeing them.
  • On the other hand, there is the problem of not being able to detect possible asteroids with a collision trajectory against the Earth. The satellites, present during the night, would leave the images useless, and many asteroids could be unnoticed, and impact the Earth without us having been able of doing anything.
  • Finally, the impacts against satellites could happen regularly, leaving in space a big quantity of space junk. This one is each time more frequent around the Earth and can represent a true danger in case of an impact against a spacecraft, the ISS, or other satellites. Moreover, the impact would create even more space junk, which would increase the risk of other collisions, and like this indefinitely.

In the following articles, I will talk about these three big problems of mega-constellations in more detail. As much as the project offers us to improve internet connection, it also has a few adverse effects that must be taken into account.

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