In May 2021, a hole was discovered in a robotic arm aboard the International Space Station (ISS). The alleged culprit was a piece of rogue space debris. While fortunately no astronauts were injured, this refocused attention on the growing problem of orbital debris.
How did we get here?
It’s easy to forget that just seven decades ago, the Moon was the only thing orbiting the Earth. As of January 1, 2021, 6,542 satellites were in orbit. Tellingly, only just over half of them were active. That’s a lot of useless metal traveling the planet at 28,000 km / h – ten times faster than a bullet.
Jan Wörner, the former Director General of the European Space Agency, put it this way: “Imagine how dangerous navigation on the high seas would be if all the ships ever lost in history were still drifting above the sea. ‘water. “
The smallest fragments can still cause immense damage, including stray nuts and bolts and frozen particles of rocket fuel. Even the paint stains are a threat – they forced NASA to replace several damaged windows in the old space shuttle. Orbital debris the size of a millimeter, according to NASA, represents the highest end-of-mission risk for most robotic spacecraft operating in low Earth orbit.
How serious is the problem?
Very bad and getting worse and worse. Estimates suggest that there are currently half a million marble-sized debris or larger and 100 million debris larger than a millimeter in diameter. Yet only 27,000 pieces are actively tracked by the US Department of Defense.
The ISS has had to perform 29 debris avoidance maneuvers since 1999, including three in 2020 alone. It does not help that some countries have decided to deliberately detonate their satellites with missiles as part of air maneuvers. military trials. One such move by India in 2019 produced 400 shards of space debris.
Space will only get more crowded, with the number of satellite launches expected to quintuple over the next decade. In January 2021, 143 satellites were launched into space on a single SpaceX Falcon rocket. SpaceX’s satellite internet company – Starlink – wants to put 12,000 satellites into orbit over the next five years. All this additional material greatly increases the risk of collisions and the dreaded Kessler syndrome.
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What is Kessler Syndrome?
It is a catastrophic chain of events in which a satellite is shattered by a piece of space debris (or a collision with another satellite) and the resulting debris destroys more satellites, creating more debris and so on in an endless waterfall. It’s a domino effect – one coin falls and takes the rest with it – and is named after NASA scientist Donald Kessler who described the dangers in 1978.
According to a 2020 Space Sustainability report from the Organization for Economic Co-operation and Development (OECD), Kessler syndrome has the potential to render certain orbits unusable for human activities. They say internet, weather and communications services are the most likely to be disrupted.
How close are we to triggering it?
A 2013 UN report predicted catastrophic collisions could occur once every five to nine years for the next two centuries.
It’s already happening. In 2009, an Iridium communications satellite collided with the abandoned Russian satellite Kosmos 2251, destroying both spacecraft. This event occurred at about the same altitude as one of the greatest dangers: the eight-ton Earth observation satellite Envisat. It will remain in orbit for the next 150 years and there is a 15-30% chance that it will collide with other space debris during this time.
Kessler syndrome doesn’t have to come on quickly. These impacts could be the first domino, with accidents increasing dramatically over time.
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What can we do about it?
Better regulation of new launches would help, because right now it’s a bit of a scrum. There are regulations in place to try to mitigate the dangers, such as a 25-year desorbit rule for low earth orbit missions. However, ESA’s Space Debris Environment Report says less than 60% of people flying in low Earth orbit are currently playing by the rules. The penalties for violators should be more severe. We must stop deliberately detonating satellites.
Increased surveillance of existing space debris is useful because active satellites can be moved off a collision course by firing small thrusters. Yet the dead satellites are sitting ducks and there is nothing we can do to avoid a collision.
That’s why many ask for a cleaning job. In 2018, the British-built RemoveDebris mission tested a space debris harpoon in orbit. ESA has commissioned the world’s first space debris removal mission. Called ClearSpace-1, it will launch in 2025 and attempt to desorb the top stage of a rocket left in space in 2013.