Kessler effect. A cosmic boundary that could seal us on earth for generations to come

Above our heads is a boundary shared by all mankind. It does not happen between two states. Of the living people there, generally few managed to visit. This border is inhabited mainly by automatic vehicles, military and telecommunications satellites and probes. And the number of inhabitants there, between the earth and outer space, is constantly growing, and in recent years this growth has simply become rapid. If we screw up, then this limit can be sealed for us for generations – so that not a single person can leave the earth anymore.

The subject of today’s story is the Kessler syndrome, a theoretical mini-apocalypse in low orbit around the earth, which, like a domino, begins with a single collision and soon makes near space completely unusable. And the risk of this apocalypse is growing because of military training and Elon Musk’s activities.

Most populated orbit

Most satellites, as well as all habitable space stations, use low orbit around the earth. This is a zone within 160-2000 km above the earth’s surface. Very comfortable heights from which telecommunication satellites give us communication and entertainment, remote sensing satellites make their beautiful maps of the planet and spy units gather intelligence.

At an altitude of about 400 km, the International Space Station orbits, where humanity has a permanent outpost in space. At about the same height, China is building its orbital station.

Low Earth orbit is extremely important for the current way of life on the planet, including for many digital services to work.

But since this is a very popular orbit, its population is growing very fast. In recent years, it has gone very fast. In September last year, there were 3,790 satellites in low orbit around the earth. Many of them are already out of order. A significant portion of this array (almost half) belonged to a single company – Elon Musk’s SpaceX. We are talking about the Starlink satellite communications network itself, which in the coming years wants to multiply the presence of its units in low orbit around the earth by several times.

Falcon 9 launched 53 Starlink satellites into orbit today. It was the 15th launch of a bunch of satellites since the beginning of the year. The Starlink constellation has already grown to 2706 satellites in orbit and will not decrease.

For the most part as humanity flirts with space, flights there, as well as satellites in orbit, were government and military. It was more of a toy for the political struggle of the Cold War. But the new century, technology and cheaper aviation have paved the way for greater commercialization of space and low orbit around the earth. Now more private companies are building their own satellites and delivering them with the same private rockets.

Too narrow path

But there is a big problem with this trend. Low soil is not rubber. The altitude range to which the satellites turn is large. In addition, the more satellites, the greater the risk of collision.

Okay, a couple of satellites will collide, a couple of rich companies will lose their money. So what? The problem is not the loss of these satellites, but the huge number of fragments formed as a result of the collision.

In 2016, on 23 August, the European Space Agency noticed a slight sudden decrease in the power of the Sentinel-1A solar panel. At the same time, some changes in the satellite’s orientation and orbit were noted. Cameras mounted on it showed damage to one of the solar panels, a deep dent that was not there before.

Analysis of data, including the speed of the satellite, the size of the dent, showed that the impact was caused by a very small object – a particle only a few millimeters in diameter, which left behind a dent with a diameter of 40 cm It was impossible to track this attacker, because from the ground usually detect potential threats greater than 5 centimeters.

Experts from the European Space Agency believe that about 129 million objects larger than one millimeter can orbit the earth. Specialists from the United States in low orbit around the earth have a couple of tens of thousands. They spin at high speeds. And a piece of such debris the size of a coin at a speed of tens of kilometers per second can penetrate a satellite with incredible force and crush it into small pieces. Dozens, hundreds and thousands of new bits and pieces.

In 2009, the very first and loudest collision in the history of the development of low Earth orbit occurred. The orbits of the operational telecommunications satellite Iridium-33 and the Russian military satellite Cosmos-2251, which had worked out 14 years ago, were crossed. Two artificial objects weighing 600 and 900 kg collided and formed, according to different estimates, from 600 to 2000 fragments of different sizes. Most of them are still in orbit, and it’s good if they leave it within the next two decades.

It was an accident that no one seriously traced. But in addition to accidents, there are patterns. Large space forces periodically multiply debris in orbit purposefully. During the Cold War, both the United States and the Soviet Union tested anti-satellite weapons, especially blocking the orbit. In 2007, at an altitude of almost 900 km, China destroyed its spent satellite with a rocket. Incidentally, this test has something in common with the plot of the movie “Gravity”. More recently, in November 2021, another test was conducted by Russia. The wreckage of the destroyed Kosmos-1408 satellite repeatedly forced the ISS crew to take cover in emergency capsules in the event of a collision with the formed junk galaxy.

The more debris in orbit, the greater the chance that they create even more debris. Which leads directly to a dangerous chain reaction called the Kessler effect.

Kessler chain reaction

NASA consultant Donald Kessler described a hypothetical scenario as early as 1978, the list of which lies in the domino effect. A collision can lead to a series of new ones, and they will cause a cascade of more collisions. After a couple of iterations, a form of chaos will be created in low orbit around the earth, which can make the earth near space completely unsuitable for human activity. No new satellites, no trips to the moon and Mars. Each rocket launch will be accompanied by the illusory risk of crashing into a dome of debris around the earth.

Of course, these debris will not permanently contaminate the orbit. Over time, they will begin to lose momentum, their height will decrease, they will slowly descend to the upper layers of the atmosphere and burn up in it. However, this is a slow process. Some debris takes decades to clear away. The more of them there are, the longer the process for self-cleaning the orbit.

But we must not wait for the development of this hypothetical Kessler scenario, but act in advance. Starlink, for example, promises to keep its orbit clean and tidy in everything to do with its satellites. They are equipped with engines on board to get out into the cycle at the end of the work cycle. If for some reason the satellite’s engine does not work, it will simply burn out in the upper layers of the Earth’s atmosphere. It is true that this takes from one to five years.

Many satellites have been launched and continue to be launched without a contingency plan for their orbit. Everything is at the mercy of the natural process. That is why specialized scavengers are needed for forced descent. Different options are offered. From vehicles with harpoons and nets that can catch debris, to robotic arms that will be more gentle on spent satellites.

In 2018, the British sent the test research system RemoveDEBRIS into orbit. It was a miniseries, in which various techniques for destroying debris were tested on targets – a net, a harpoon and a sail.

It was possible to wrap the test target with a network, but they did not plan to actively lower it from orbit in the future in any way.

A harpoon shot with a speed of 20 m / s also succeeded. They struck, they caught, but they did not let go.

The last experiment with the sail was perhaps the most interesting from a practical point of view. The sail was intended to act as a natural brake for this entire research platform, which thanks to it would have ended up in cycle. But the sail could not be inserted – the experiment failed.

In 2026, the European Space Agency plans to launch a cleaner into orbit as part of the ClearSpace-1 mission. It is intended to remove the Vega payload adapter from the orbit, which was left over from one of the launches ten years ago.

The assignment had already been postponed once and the contractor had failed to design the cleaning appliance. Will it be possible to test promising technology in time? There are doubts.


No one has ever cleaned in a low orbit around the earth. So far, we are only creating even more rubbish there, and putting spokes in the wheels of future generations so that they can use spaces close to the earth in a safe way.

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