“With the advent of mega-constellations of satellites like Space-X’s Starlink, will we have to play Crossy Road in an orbital version before launching a spacecraft?” Nowadays, we hear more and more about constellations and mega-constellations projects consisting of hundreds or thousands of spacecraft. A satellite constellation is a group of artificial satellites working together. The satellites orbit in selected and synchronised orbits so that their respective ground coverage overlap and complement each other instead of interfering with each other.
Today, many businesses and other users, such as the general public, demand better and more efficient connections. To respond to them, more and more efficient communications technologies are developed and implemented. Today, several “mega-constellations” projects are being organized to connect the seven billion human beings inhabiting our “blue planet”.
Starlink is a project organized by SpaceX and which aims to provide high-speed internet access throughout the planet by mega-constellations. Currently, Internet access depends on satellites transmitting Internet via towers and cellular cables. However, these two options do not allow Internet access in some remote areas. Today only fifty-seven per cent of the world’s population has access to the Internet. Disparities are felt in some regions such as Central Africa where only twelve per cent of the population has access to the Internet. Elon Musk’s project would allow broadband internet access across the globe at an affordable cost thanks to several high-performance satellites placed in Low Earth Orbit (LEO) above five hundred anf fifty kilometres from Earth. This project of a mega-constellation would benefit a lot of people, but does the end always justify the means?
Starlink is not the only mega-constellation project. With the same goal, the startup OneWeb plans to send six hundred and fifty satellites to one thousand two hundred kilometers altitude by 2021 and therefore create a mega-constellation. However, the company OneWeb, declared bankruptcy at the end of March. Moreover, Jeff Bezos, talks about launching three thousand two hundred satellites between at an average altitude of six hundred kilometers. This mega-constellation is based on small satellites in LEO between three hundred and fifty and one thousand kilometers altitude. However, there are several concerns about mega-constellations such as the issue of orbit congestion and space debris.
THE ORBIT CONGESTION
In 1976, eight States traversed by Equator signed the Bogota Declaration in which they requested their rights over geostationary orbit as a natural resource that had been unfairly removed from their sovereignty. The Geostationary Earth Orbit (GEO) is the circular orbit located at a distance of 36.000 km above the Earth’s Equator. A satellite placed in this orbit always fixes the same point. The GEO satellites are used for TV, telecommunication services and other applications.
The Bogota Declaration is the evidence of the fear among developing countries that no space will be left for them to launch geostationary satellites in the future due to orbit congestion. Though, the Bogota Declaration did not receive wide international support nor recognition. Moreover, the Article 2 of the Outer Space Treaty provides that “outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means“. The geostationary orbit is in fact part of outer space and the 1967 Treaty therefore invalidates the sovereignty claims of the Bogota Declaration. Yet, Article 33 of the 1973 International Telecommunications Convention defines the geostationary satellite orbit as limited resources that may have equitable access.
Starlink planned to deploy about twelve thousand satellites by 2027 with the objective of sending a total of forty-two thousand satellites if the company obtains the authorization. To give an overview, in 2019 there were two thousand active satellites in orbit around the Earth and thirty-four thousand objects larger than ten centimetres in size. This monopoly of the orbit raises the question of the equitable use of this resource by these companies. Above all, however, mega-constellations raise the risk of orbital congestion, which could seriously hamper future space missions.
The problem of congestion is directly related to the risk of a significant increase in Earth orbit debris. The increase in the number of objects in orbit necessarily increases the chances of collisions between aircraft. Concerning Starlink project, placing the satellite in LEO, will allow them to de-orbit in a few months thanks to their own propulsion system, whereas a traditional satellite placed more than one thousand kilometres from Earth takes one to five years to de-orbit. However, Starlink’s satellites or those of other mega constellation projects are likely to fail. It is estimated that already three per cent of Starlink’s satellites are out of service; these satellites are no longer manoeuvrable and are therefore likely to collide.
This risk is real and has already been observed. In September 2019, the European Space Agency had to perform evasive maneuvers on one of its satellites in order to avoid a collision with a mega-constellation of SpaceX. In this case, the device in question was in operation, but its anti-collision device was deactivated. Therefore, if nothing is done to prevent these risks, repeated collisions could occur, which could lead, in the extreme, to Kessler’s scenario: an exponential increase in debris and impact probabilities that would make space exploitation impossible.
The law is silent on the subject of space rights and mega-constellations. Jean-Yves le Gall, head of the French space agency and former president of the IAF, believes that mega-constellations would make it necessary to establish an international law on waste: “There are practically no examples of satellites that have had a problem because of debris. But this is beginning to become urgent because of the mega-constellation projects. SpaceX doesn’t do anything that breaks the rules, the problem is that there are no rules. There are air traffic controllers for airplanes, we’re going to come up with the same system for space“.
Without an international law to control behaviour, it is up to the States to legislate waste treatment. In this field, only France has a law requiring that all aircraft in low orbit be de-orbited within twenty-five years. For the rest, national agencies such as NASA have adopted non-binding rules for their own satellites. Thus, everything depends on the good conduct of operators. To date, a Space Safety Cooperation charter, signed by thirty-four players in the sector, including Airbus and OneWeb, aims to regulate the production of debris in orbit. Other directives, such as those of the Inter-agency Space Debris Coordination Committee, created in 1993 by NASA and the European, Russian and Japanese space agencies, issue non-binding recommendations, one of which is based on French law.
But like all environmental issues that present long-term challenges, simple rules of good conduct may not be enough to stem the spread of space debris; it would be enough for an operator not to respect them to spoil everything.
Several satellite recycling projects are underway. Space Advanced Concepts Laboratory is trying to set up a kind of autonomous garage in orbit that would house spaceships to diagnose the state of the satellites, to repair them but also to tow them for recycling. This project is expected to come to fruition within the next fifteen years or so. It would partly solve the problem of space debris and increase the lifespan of satellites. Another project proposed by the start-up Clear Space aims to send a satellite whose mission will be to capture space debris using four robotic arms.
However, these projects are not yet implemented and finding investors is very complicated since they will not bring benefit. The mega-constellation would be a great technological breakthrough for Internet access in particular, however the risk of congestion and an increase in space debris pose real problems.
This article was written by Corinne BAUDOIN, Laetitia PIETRI, Pierre-Yves VILLARD, Guillaume BRESSON, Bianca-Laetitia TOMASI, Élise DRILHON and Esther SENG GARCIA (Paris-Saclay).