Thing #314159 That I Won't Worry About This Week

Or for the next couple hundred years, for that matter: Kessler Syndrome.  [TLDR: A chain reaction of satellite collisions that release more flying debris that collide with more satellites, until an entire orbital altitude band is left completely unusable.  Most likely in the most useful ones, because that's where the satellites already are.  If any of this rings a bell, it was a plot device used in the book Retrotopia and the movie Gravity.]

So I was talking with a Knowledgeable Person about such things this just-passed summer, and when the Kessler topic came around his reply was "Yeah, don't worry about it.  Takes too much energy to change orbits."  Vigorous handwaving ensued.  "OK, but has anyone run some Monte Carlo simulations to get a rough idea?  What are the numbers here?"  He didn't know, didn't consider it worth worrying about.

Wait, wait, let's break for a Heinlein quote:

What are the facts?  Again and again and again – what are the facts?  Shun wishful thinking, ignore divine revelation, forget what "the stars foretell," avoid opinion, care not what the neighbors think, never mind the unguessable "verdict of history" – what are the facts, and to how many decimal places?

Well, as it turns out more than one research group has done some calculations.  Here are links to three of the better papers: 1, 2, 3.  The results are not actual facts mind you, but reasonable estimates based upon the best numbers we currently have.

Bottom line?  Two hundred-plus years.  So don't worry about it.  Here's a plot from the second link.

Really, don't worry about it, at least not for now.  It'd be like someone in 1781 worrying about what technology-driven problems could be happening by now – possibly a lack of suitable timber for ships' masts.  Of course I'm not saying that we shouldn't keep track of such things, and if a solution is not within easy reach by say 2200 we ought to step up the mitigation efforts.  What's more, these estimates might be off by... probably not more than a factor of two (i.e., 121 years).  However even that's beyond the foreseeable future.  So keep an eye out, but really, for now don't worry about it.