The Kessler Syndrome: Closing Off Earth From Space
When writing about outer space, I often compare it to the vast and plentiful oceans here on Earth. Both are mysterious frontiers as yet largely unexplored and with magnificent potential — from sunken cities and trench inhabitants to strange planets tidally locked to their stars, creating a surface of duality where scorching temperatures coexist beside glacial, shimmering tundras. They’re also immense; looking out across the faceted blue of the waters it seems to be infinite. Grand and indomitable. It’s because of this illusion that we’ve had a terrible effect on the ocean’s ecosystem. We’ve depleted fish populations, killed half the Great Barrier Reef, and continue to add more than 8 million tons of plastic into the ocean each year. We’re treating the space around Earth in much the same way.
It’s difficult to believe with such clear night skies — freckled with luminous bodies of stars and planets — that anything exists up there which might hinder space exploration. And yet much like the iconic rings around Saturn, there’s a growing ring of debris circling Earth. It’s composed of dead satellites, slivers of paint, fragments of solar panels and rockets from missions long ago. Altogether there are millions of pieces of debris in orbit with only 22,300 of those pieces regularly tracked by the US Military. Theoretical models are needed to predict the path of any debris under 10 cm, which can’t be tracked. And while the military has the largest public database of space debris, even this doesn’t include satellites omitted by international governments, commercial companies, or our own ongoing projects.
The most frightening aspect is that all of this material is not merely tame and floating around but rather moving at speeds as high as 17,000 miles per hour (27,000 km per hour) with each object varying in direction as it’s affected by the Earth’s gravitational field. Friction of an object against the atmosphere will also cause some objects to fall in altitude. At these speeds, a screw can have the same impact as a high-speed car, potentially destroying an entire satellite. These are the same satellites we depend on for everything from communication to ATM withdrawals to monitoring of the Earth’s ecosystems. Avoiding collisions through evasive maneuvers uses up the satellite’s fuel and time, making it less efficient than it could be. Even more problematic is the fact that most objects in orbit cannot be controlled from Earth so there’s no way to interfere with debris on a collision course.
This is the fear addressed by the Kessler Syndrome. It was a theory proposed 41 years ago by NASA scientist Donald Kessler. The theory describes an ongoing collision of debris where an initial incident continues to cascade into another and another, giving way to an exponential rise of debris around the planet. In fact, some scientists believe the effect might already have been put into place by the events of 2009.
That year, an operational Iridium satellite and a defunct Russian satellite struck one another at the rate of 26 miles per hour (42 km) and created 2,000 new pieces of debris. This occurred at Earth’s polar orbits at a height of 490 miles (789 km) in altitude. This area at the poles is considered to carry the highest risk of debris collision.
While most causes of debris are accidental, like the incident above, an unsavory plan in 2007 angered many countries across the world. China destroyed a weather satellite and created thousands of new pieces of junk orbiting above us right now. The test itself was already controversial, aimed to test their capabilities of destroying objects in space. The US also caused a lot of pollution in the 1960’s when it sent millions of copper needles into space to improve radio communications. While some of these needles came back down, thousands of clumps of copper still reside up there to this day.
And since the 1960’s, space’s artificial population of objects continues to grow rapidly with 400 new satellites having entered orbit in 2017 alone. This number doesn’t seem to be going down. SpaceX received approval last year to launch 12,000 new satellites and they’re only one among many companies with plans to deploy similar satellites in the near future. Technology like CubeStats — small scale satellites enabling research groups and companies to have access to space — are cost effective and accessible, meaning they’re being increasingly deployed as well. If these rates continue to increase and nothing is done about the problem, collisions can become up to 25 times more likely, meaning that spaceflight would be almost impossible.
A little over a decade ago, agencies developed guidelines for the launch of spacecraft. Satellites should turn off batteries and vent all fuel and combustible material to avoid in-orbit explosions. The altitude of these satellites should also be low enough that they will naturally burn up after 25 years, meaning they should come below 372 miles (600 km). This foresight is known as the passivation of objects. Debris will burn up upon re-entry to Earth’s atmosphere, though this does come with the potential for larger pieces of debris to land in populated areas. Only half of all missions abide by these guidelines.
Unfortunately, a critical point for space debris has already been reached. Even if no further launches were to take place, the number of objects would continue to increase as more and more collisions occurred. The only long-term solution is to remove 5–10 large objects from orbit each year. And experts urge us to begin this process of removal now. Proposals for cleaning up space include nets to capture objects, lasers to guide them into re-entry, and large magnets to attract the pieces. But technology for managing space debris is still under testing and development. For now, the best agencies are able to do is to track the moving objects.
Artificial intelligence with neural networks — the machine equivalent of a human brain — can be used to track debris and give a prediction of where it will be in the future. The AI is capable of learning from its mistakes and becoming more accurate as time goes on. It could also suggest the best launch times since research shows that even a difference of 15 minutes in launch time can influence how long it will take a satellite to come back down. Massive data sets are not only cataloging objects but also studying sizes and shapes in order to better asses the danger a piece of debris will pose.
Everyday, 21 warnings of space collisions are issued by the US military. And while we think of pollution of our oceans as having a great impact on human and animal life, it’s important to remember that pollution of space impacts our lives just as much. Our societies and economies are reliant upon those satellites, now vulnerable to severe damage from our past endeavors. Not to mention the risk faced by astronauts onboard the ISS. A future in which we cannot continue to explore — whether that be space, land, or oceans — is a dismal one, and one which would strip us of a very important part of our humanity.