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In recent years, satellites have become smaller, cheaper, and easier to manufacture with standard commercial parts. Some even weigh as little as a gram. This means more people can afford to send them into orbit. Now, satellite operators have started to launch mega-constellations – groups of hundreds, if not thousands of small satellites working together – into orbit around the Earth.
Instead of a single large satellite, groups of small satellites can provide coverage of the entire planet at once. Civilian, military and private operators are increasingly using constellations to create comprehensive and continuous coverage of the Earth. Constellations can provide a variety of functions, including climate monitoring, disaster management, or digital connectivity, such as satellite broadband.
But to cover the whole planet with small satellites, you need a lot. On top of that, they must orbit close to the Earth’s surface to reduce coverage disruption and communication delays. This means that they occupy an already occupied space area called low Earth orbit, space 100 to 2,000 km above the Earth’s surface.
There are many issues associated with bringing these many satellites into orbit, from the dangers of space debris to obstructing our vision of the night sky. But the shift to mega-constellations is also a challenge for global space governance.
There are nearly 3,000 active satellites orbiting the Earth today, and this is expected to skyrocket in the years to come. The European Commission, for example, recently announced plans to launch thousands of satellites into orbit around Earth, adding to a growing list of planned mega-constellation launches.
As businesses and governments around the world continue to seek mega-constellations, it’s critical that the governance framework is able to support the surge in activity. A number of important issues must be taken into account.
1. Definition
Satellites are regulated at the national level and by licensing, guided by the principles of the 1967 Outer Space Treaty. Although the terms constellation or mega-constellation do not appear in the treaty, they are considered like space objects, like all other satellites.
With procedures and regulations varying from country to country, the challenge is how to govern the mega-constellations without creating legal fragmentation. It is imperative that the subject be debated at the international level.
Yet at this time, there is no legally binding definition for a constellation of satellites, nor for the more recent term mega-constellation. The exact number of satellites that make up a mega-constellation is unknown, and each country might consider the term to mean something different. Clarity at the international level could pave the way for the creation of guidelines specifically for mega-constellations, which could aid in the safe and sustainable use of low earth orbit.
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2. Congestion
Most satellites in low earth orbit operate between 600 and 800 km above sea level. This is considered a congested area because there are already a lot of satellites. Small satellites have a shorter lifespan than larger satellites, which typically orbit above low Earth orbit.
However, it may still take up to about 150 years for satellites to retreat, re-entering the atmosphere and burning, if they are about 750 km above sea level. Some are removed on purpose, through controlled reentry, and others are designed to fall uncontrollably. Operators of satellites and mega-constellations should consider ways to reduce the debris caused by these satellites beyond the usual procedure, in order to maintain sustainable use of low earth orbit.
Considering the number of future mega-constellations currently planned, the space around Earth called low Earth orbit could easily become a finite resource.
3. Radio spectrum
This is not only true for the physical space, but also for the use of the radio. To communicate, satellites use the radio spectrum. With the increase in mega-constellations, there is a risk that operators will “store” radio frequencies, storing them before they actually need them.
To avoid this, a United Nations specialized agency for the use of radio spectrum by satellite recently updated its regulatory framework, treating the issue separately from other space regulations. The mega-constellations will be placed on a flexible timeline, receiving only the use of the frequencies they need at that time.
4. Collision avoidance and tracking
If low Earth orbit becomes crowded with satellites and mega-constellations, avoiding collisions will become more difficult. In September 2019, the European Space Agency had to trigger the boosters on one of its satellites to put it out of range of another satellite, otherwise the two would have collided.
As the orbit becomes more congested, there may be a need for more collision avoidance maneuvers and better communication between satellite operators.
There are national efforts, mainly in the United States, for satellite tracking and collision avoidance maneuvers. A system alerts satellite operators to potential collision paths and allows heading corrections when possible.
Go forward
Hopefully the mega-constellations will be discussed by member states at the UN as soon as they are able to do so. Although the work in the committee can be slow and highly political, international guidelines as well as national licensing procedures must take into account mega-constellations.
The benefits of constellations and mega-constellations in low Earth orbit for socio-economic and environmental purposes are considerable. For this reason, it seems likely that the number of constellations will increase in the near future. To prevent problems from arising, the rules and definitions surrounding mega-constellations need to be clarified, internationally.
This article by Lauren Napier, PhD Researcher in Space Law and Policy, Northumbria University, Newcastle is republished from The Conversation under a Creative Commons license. Read the original article.
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