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Comment by ajnin | Hacker News Reader

The rate of satellite launches seems to be increasing at an ever-greater rate. With the advent of SpaceX, ISRO, and many new actors in the launch business space has never been so cheaply accessible. A runaway Kessler Effect (https://en.wikipedia.org/wiki/Kessler_syndrome), making space access for everyone problematic, seems now a real possibility, especially if a few bad actors launch junk into space with disregard for the safety of others.

I'm not sure who should be responsible, but some coordination at the international level seems necessary to make sure this does not happen.

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Do you have any links with more analysis on the problem today?

Kessler syndrome is something I always see discussed, but I don't really have any idea how large/proximal the issue is. Is this a 10-years risk? 100? 1000? Purely hypothetical?

I have read a few hard analysis papers over the years and the gist is “it depends”. If things went bad, a worst case Kessler syndrome cascading failure. It could take upwards of a year or even more to actually impact the majority of space assets.p, remember “space is big”. And in addition to the time the events would take to unfold, the time they will continue to affect the availability of safe orbits will depend on the altitude of the orbits and the mean particle density. Less dense objects at lower orbits will be more affected by the thin air drag and decay sooner, gradually clearing the orbits over a period of years. Meanwhile the higher orbits will continue to have collisions and junk orbiting for varying degrees of forever.

Overall the situation is best modelled with a pretty messy set of differential equations combining the differing rates of debris creation and decay by altitude alongside the rate of impact events that cause gradual reduction in the mean particle size and orbit.

As for the risk, it’s sort of a chaotic breakdown threshold, hard to model. And unfortunately also hard to predictively put risk estimates on.

Very interesting--thanks for the reply.

I sometimes forget there are problems out there that for all our analytic tools are 'too hard' to give an good (read: short) answer.

I'll have to go properly digging for some papers, though it's been a few years since I had to read differential equations...

ISRO has been around since the 70s

Yes, but I was under the impression that they have ramped up their commercial launches substantially in the last few years, and that they are sending more small satellites clusters recently. Maybe I'm wrong about their launch history, but my main point still stands.

And they do a very small number of launches every year.

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