21st Century Problems: Space Junk

How could exponential growth destroy your GPS, internet and cellphone reception?

It’s a great question. They’re largely satellite-based and satellites are just “up in space” somewhere, right? No pollution, rising sea levels, interference or congestion, right? No nasty collisions or crashes could possibly occur between all the intricately carefully planned satellites, could they? Not with all those smart engineers and such?

Well, actually, check out some of this:

  • There are between 20,000-30,000 manmade objects greater than 10cm orbiting the Earth, with 20% remaining from spacecraft launches and 80% from non-operational satellites
  • There is another half million pieces smaller than that, including nuts, bolts and other small debris
  • That totals of 7500 tons of debris orbiting above us, with an estimate of only 1500 working satellites
  • And, an average of 1 piece of space junk has fallen to Earth every day for the last 50 years
600px-Debris-GEO1280
A computer-generated image of satellites orbiting Earth (Wikimedia Commons)

These are spread out between geosynchronous Earth orbit (orbit in the same length of time to takes for Earth to rotate once- literally, high Earth orbit) and low Earth orbit (closer to us). There is a far greater density of low and mid Earth orbit satellites which are used for telecommunications (your email, internet and so forth) and navigation (GPS) and they orbit up to 15 times a day.

And the problem is just the sheer number, represented by all the white “dots” in the image. Every time that something is launched, we collect more dots as remainders of the launch equipment and the new satellite itself.

So, low Earth orbit is filling up fast.

Why?

It’s all our fast and wide internet coverage. Every GPS satellite. Observation and weather satellites. And then all the little extra bits like loose nuts and bolts or even a single fleck of paint that caused a crack in an ISS’s (international space station) window.

The problem is increasingly exasperated if two pieces of debris collide … then we can get a whole bunch of little pieces. Then all the littler pieces can collide with more pieces and then more pieces…..

12-exponentials-11
A generic exponential growth curve

We call that exponential growth, when the number of “things” increases more rapidly when there are more things. So if we take the 20,000 pieces of space debris larger than 10cm (this is large enough to destroy an entire satellite in a collision) and imagine a couple of those colliding. Then we’ll have heaps more larger-than-10cm pieces to collide completely with other satellites in a completely uncontrollable manner, as seen in the sci-fi film, Gravity.

The question is, is there currently enough space debris to result in these uncontrolled collisions and ripping apart of our “essential” satellites?

Scientists call this the Kessler syndrome, where there is a ‘critical point’ in the number of space debris. If this critical point is reached, then low Earth orbit will end up in this disaster-scenario of millions of tiny debris and you can say goodbye to your internet, phone and weather forecast.

However, we’re left with the problem that we don’t know quite where the critical point is. We could have already over-reached it and be on the very edge of massive collisions. Or maybe we’re not quite there and we just need to stop launching stuff into space.

Unfortunately, there’s almost nothing by way of international guidelines for launching things, so it’s not too hard for individuals to disregard the long-term impacts of their satellites and associated debris. Turns out we aren’t satisfied just polluting Earth, we’ve decided to pollute space as well.

 

So what’s the solution?

We also don’t have too many ideas about how to go about cleaning this mess up either. China blew up one of their satellites to test anti-satellite weaponry … and created over 1600 pieces of space debris from it.

More hopeful initiatives focus on “catching” debris with another satellite. One such group is CleanSpace One, a Swiss group that have designed a satellite that will catch small, unused satellites and actually recycle them. Other groups have done similar, and if we get started sooner rather than later then we might be able to make some progress.

I think it also illustrates our disregard of resources even further. We use space as an available resource for telecommunications, navigation, weather, etc.. but have once again neglected the long-term impacts.

It’s easy to draw parallels: global warming is destroying life’s diversity and threatening coastal areas and space debris is threatening much of modern technology.

 

 

 

 


4 thoughts on “21st Century Problems: Space Junk

    1. It is shocking and a very real issue! As to leaving Earth safely, NASA tracks over 500,000 pieces larger than marble-sized and as you can imagine, they do the calculations to avoid hitting any junk. It’s not too hard for one-off things like leaving Earth because space is pretty big for all the junk, but it becomes more of an issue when you keep things up there for an extended period of time travelling at different speeds (like satellites), then the chances of collision increase. Just to put all of this into perspective, the International Space Station generally has to change course about 3 times a year to avoid debris.

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