Every now and then I’ll hear about space junk as a Thing To Worry About. Yesterday, the IEEE said “we’ve already passed the tipping point for orbital debris,” complete with a disproportional depiction of Earth surrounded by thousands of pieces of junk that would each have to be the size of New York City to be visible from that range.
Active spacecraft and satellites are increasingly endangered by “the by-product of thousands of launches and routine spacecraft deployments, nearly 200 explosions, and several collisions.” If things get too crowded, collisions will lead to more collisions in a catastrophic feedback loop that will basically be Very, Very Bad For Everyone and Everything.
It’s not really so bad, is it?
At first blush, I’m tempted to think we must be a long way from this becoming a real problem. To put things in perspective, we’ve been building things on our planet for thousands of years, and yet from an airplane – or better yet, from orbit – the vast majority of our land masses still look completely uninhabited. Now Earth has about 150 million square kilometers of land mass. This space junk looks to be around an average altitude of 800km, which means there’s a “surface area” of around 4π(7100)^2 or over 640 million square kilometers of space to put stuff, and we’ve apparently only got about 20,000 objects up there.
Furthermore, they’re spread out over about 1000km of altitiude, which makes things even less crowded up there. At this point, my guesstimating is compounding enough to be dangerous, but there could be an average of hundreds of miles separating most of these debris pieces from each other.
Of course, the problem is that most of these pieces are moving in their orbital paths at something like thousands of miles per hour. Imagine 20,000 airplanes constantly flying around the globe at supersonic speeds with no one guiding them, and new ones constantly being added. And of course some areas more crowded than others. Suddenly mid-air collisions sound like much more of a problem than they already are.
There was one dangerous orbital collision three years ago. It’s easy to see this becoming more and more of a problem, especially as each collision creates more junk that makes the problem worse, even if the collisions are still years apart – for now.
At its core, the space junk problem is a problem of economic externalities. No one owns the space up there, so no one has an incentive to keep it cleaned up. It’s the Tragedy of the Commons on the largest scale ever observed in the history of humanity. Property rights are generally recognized as a foundation for economic prosperity that aligns short-term self-interest with long-term self-interest, but property rights are generally assumed to cover two-dimensional space and whatever you can build on top of that. How do you claim, enforce, and defend property rights in an empty three-dimensional space?
Parallels With The Oceans
I don’t know how this externality will be solved by the powers that be, but I look to the oceans for optimism that a solution will be discovered. Like the orbits above, the seas are a vast three-dimensional space without physical barriers where water and its contents move around at will. The oceans are filled with vast resources of animal and mineral, but for the most part humanity’s stewardship has been relatively peaceful – the current row over an Asian island notwithstanding – and successful.
We still have problems with the ocean, to be sure. The Tragedy of the Commons manifests itself in overfishing and in the Great Pacific Garbage Patch. But we have yet to fill the oceans with so much trash that it’s unusable, or deplete the oceans of so many fish that they become extinct, and there are plenty of parties interested in preventing these things from happening, including the businesses that profit from these externalities.
That’s why I have hope for Space
I’m optimistic that a similar thing will happen with outer space. We may have to wait for a few more externality costs to pile up to spur the necessary action, but I’m not worried about an irreversible tipping point, especially if humanity comes up with a way to cheaply clean up the orbits or launch the junk into the gazillions of cubic kilometers of actual outer space.
Maybe countries will monitor the orbital paths above their land, though the junk may fly around too fast for that to be feasible. Maybe countries and organizations will at least agree to make each other responsible for their own junk, especially if clean-up becomes easy enough to make that practical. If there are global agreements to charge orbital littering fines, I bet some companies will pioneer orbital trash pickup.
Maybe there’s some clever way I haven’t thought of to use property rights to resolve the externality without regulations – I didn’t even know there was a such thing as an “on-orbit annual insurance rate,” but an increase in insurance rates due to increases in orbital collisions sounds to me like a natural self-correcting market force that creates incentives to find solutions. Whatever comes next, I believe the innovation in this area has only just begun.
I’m sure it’s possible that the growing amounts of space junk will lead to The Great Chain Reaction of Orbital Collisions That Knocks Out All The Satellites And Covers All The Land In A Second Darkness, but I’m not getting too worried. Not yet.
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