As you read this, some 13,000 satellites are hurtling through space, orbiting the Earth at breakneck speeds of 6 miles (or 10 kilometers) per second – which is more than 14 times as fast as a fighter jet. While it is an incredibly impressive feat that exemplifies the scientific progress humanity has made over the last century, it does create a rather large problem: space junk.
Enter Kessler Syndrome. This is the idea that sending too many objects to space will increase the likelihood of collisions that, in turn, generate even more space debris and raise the probability of future collisions. It is, essentially, a domino effect – and some scientists argue that we may reach a point of critical mass from which we cannot return.
The concept was first put forward by the American astrophysicist Don Kessler in the seventies. Since then, the Earth’s lower orbit has accumulated more and more junk. According to the latest figures from the European Space Agency (ESA), published in September this year, there are currently more than 10,000 active satellites and 3,000 defunct satellites circulating the planet.
As you may guess from these figures, many items remain in the atmosphere long past their use-by date, exacerbating the problem and contributing to a build-up of tech in the Low Earth Orbit (LEO). But there has also been a significant increase in the number of satellites launched into space in recent years – most notably from SpaceX, who has launched over 6,800 as part of the “megaconstellation” Starlink. According to the Union of Concerned Scientists, an additional 2,000 were blasted into space in 2022 alone.
“Years ago, a busy year was one launch a month…Right now on average we are launching more than 12 satellites per week.” Professor Moriba Jah from the University of Texas Austin told the IFLScience podcast in 2023. “At this rate, we have no idea what the unintended consequences are of launching so many objects so frequently.”
This increase in human-made tech is on top of the millions of pieces of micrometeoroids that circle the Earth. In short, the planet’s celestial highway is getting very crowded.
But the sheer number of objects becomes an even bigger problem when speed is taken into the equation. While a 1-centimeter fleck of paint may seem innocuous, it can pack a punch when floating in space. According to NASA, it has the ability to cause the same amount of damage as a 250-kilogram (550-pound) object (think: a pig) moving at 60 miles (97 kilometers) an hour on Earth. From this, it is not hard to see how a collision with space junk could prove catastrophic, even deadly, if you are an astronaut (see: the plot of Gravity). It could also threaten our way of life – and our ability to catch a flight – back on Earth. Satellites play an instrumental role in everything from navigation to communication.
So, what is being done about it?
Many scientists, including Jah, are calling for a circular space economy; a plan that would involve shifting to technology that can be reused and recycled as well as finding more responsible ways to dispose of defunct items. One example would be to use wooden satellites, like those due to be trialed by astronauts aboard the International Space Station (ISS). Meanwhile, agencies like the ESA are launching their own programs to decrease the amount of junk produced in future missions and remove some of the debris currently in circulation in a bid to stop the nightmare scenario of Gravity playing out in real life.
Source Link: Why Are People Concerned About Kessler Syndrome?