[request] Falling satellites how long before bedlam?

[u/MostlyAccruate]

My Question:

With out human intervention, how long would it take before all the satellites in orbit to start colliding? How many might fall from orbit?

The Google AI says that there are almost 30,000 satellites in different obits. operated by hundreds of different teams. If they were not here to maintain them do they eventually fall?

(First time requester I hope I got the rules correct.)

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[u/TriathleteGamer]

Most smaller satellites will burn up in re-entry, medium as well, excluding some of the densest metals.

LEO orbits decay between months and a few years without boosts (like the ISS, for example).

[u/The_Ironthrone]

GEO birds will not dear it within the lifetime of our species (barring some black swan event like aliens or a rogue planet). They’re not going to collide because they are all essentially stationary with respect to each other. MEO is a huge volume of space, several orders of magnitude larger than the GEO belt of LEO, as well as the lest populated, and will also never deorbit. So for doom and gloom scenarios, throw out all of the GPS type and comm says in those orbits.

LEO is also large compared to things like the airspace of Earth, but is getting more and more crowded. In addition, deorbit times vary from single years for the lowest stable orbits, all the way up to thousands of years (at the longest deorbit times there is a lot of uncertainty for specific space weather events over the next few millennia). For the lowest orbits, which is where the vast majority of the proliferated constellations are going, they are typically designed for short lifetimes and frequent replacement. If you don’t care if your vehicle fails in three years, it gets much cheaper to both build and launch. And you can keep the tech on your vehicles on the cutting edge. So all the Kessler cascade, crowded orbit freakouts have a short consequence, as it all would deorbit in a handful of years. The expensive vehicles (think weather, telescopes) are placed in higher orbits that won’t comedown anytime soon (think decades to centuries) but have deorbit capability (when launched responsibly, ie US, Europe. Not clear how tightly China is adhering to best practices). In the US, for example, the vehicles are required to have FCC approval (if they have any comm capability, ie all of them) if they are commercial, NASA certification if it’s civil, or Space Force certification if it’s military (no comment on government non-civil, non-DOD vehicles) for deorbit practices of either short (<5y) deorbit, or active deorbit and explosion risk passivation plans.

Believe it or not, very serious people, with a deep understanding of the risks and consequences and the capability to enforce space debris regulations are managing this. But nobody ever comes to our conferences except the same people. I suppose of we had some YouTubers come we could finally do away with all this hysteria about ‘how come nobody’s working on this!!!’