Kessler syndrome is still limited to a range of orbits. Very low earth orbit everything simply de orbits so fast it’s not a significant issue.

Geosynchronous orbit is quite packed, but everything is moving in the same direction which prevents the kind of exponential cascade that’s so concerning. Above geosynchronous orbit’s graveyard stays clear simply because little has the energy to reach that altitude.

Yes, it's my understanding that, in practice, Kessler syndrome would most probably mean no geosynchronous satellites. It's slightly reassuring that that isn't as horrifying a proposition as it was thirty years ago. Recent advances would allow things like geonavigation and telecommunications to be supported with Starlink-style low orbit networks, even in that event.

Regarding simply transiting through our ex-satellite rings, I don't think there is consensus. Would it make launches beyond LEO practically impossible, or just theoretically risky in the way that blindly navigating the asteroid belt is? (You could hit something, but it's so little matter dispersed over so much space it'll probably just be extremely fine dust the shielding can handle. Probably.)

GEO is only above the equator, i.e. launches beyond it shouldn't be seriously affected if there was a debris belt, unless it reaches a significant density beyond a narrow belt.

To some degree that's true, though collisions will likely create cones of debris that extend significantly above and below the initial orbits, and those shards could smash satellites in those higher or lower orbits, thus continuing the chain reaction.

For example: two satellites collide head-on at an altitude of 300km, creating two debris clouds that extend from 250km to 350km. Each of those catches another satellite, one at 260km and another at 320km, which fragment into debris clouds reaching from 200km to 370km (all numbers made up).

Higher orbits, like geosynchronous, have a lot more space to work with and much slower relative velocities than low Earth orbits.

That debris cloud is an abstraction, actual post collision orbits of individual objects are what matters.

At 300km satellites experience significant drag and need regular boosts to maintain orbit. After collision individual objects orbit will almost always include it’s altitude at the point of impact and generally expends above and below that point. So while yes the cloud extends to higher orbit, everything would deorbit from your example extremely quickly.

Your last sentence is depressing. We can't even muster enough e pluribus unum to combat a pandemic within the one nation that holds that motto on its great seal.

Dealing with space debris doesn't require individual action from hundreds of millions of people though. It requires the governments of eleven countries with orbital launch capabilities (counting the ESA as one) to work together.

11 Countries? The UN Security Council has five permanent members and they don't always work together (any one of the five can veto resolutions against its own exonomic interest).

The UN Security Council isn't meant to be a politically nimble engine for progressive economic change; it's meant to prevent a shooting war between those major powers. Judging the UNSC by the standard of that design intent and purpose, the UNSC has been quite effective, a few regional proxy wars could have been much worse for everybody on this planet. We can call it a failure if/when America and China start WW3 and cover everybody else in fallout, but that hasn't happened yet. So far, the United Nations Security Council is working well.

I'm not convinced that the latter is any easier than the former.

There was an unparalleled global knee-jerk and the sort of global coordinated economic reorganisation we've never seen before in the entirety of history. The politics of the situation are still roiling under tensions and stresses that haven't been seen in decades. A vaccine has been rolled out roughly a quarter of the worlds population in 18 months. Vastly more efforts are hurtling through the economic system as humanity reorients its social and technological bearings. Never before has there been such a bleak future for the humble coronavirus.

The situation is neither pro- nor anti- our ability to organise at a mass level. This has been a remarkable 2 years to be alive and we've seen a level of urgent response that has never been achieved before, ever. With 3 years to prepare, anything is possible for this Kessler business.

Why the fuck do we not have a system to harvest/kill/detonate already deployed satellites??

Thats pretty fucking simple science, is it not?

It's not.

First, it's not just satellites. There's hundreds of thousands of pieces the size of a marble that'll cause catastrophic damage. And even more smaller pieces, even millimetre long bits of paint have caused damage to vessels.

Second, harvesting (presuming you mean recovery) or just killing (presuming you mean de-orbiting with atmospheric burn up) require expending deltaV. There has been some interesting proposals for using laser ablation or tether based systems, but nothing that I know of that has gone past a paper proposal.

Detonating just adds to the problem.

Thanks for the reply... perhaps a good policy would be to not allow any launch off-planet without a recovery / disablement plan?

AFAIK, all modern satellites launches require a plan for decommissioning them when they reach EOL.

The problem is 'What happens when the plan fails due to design errors/bugs/accidents/breakages/etc'.

Recovery of a satellite is incredibly expensive.

Space Satellite Recovery Startups are back on the menu boys!

We need both space junk recovery and ocean plastic recovery robots.

Recall that startup that tried to launch the ocean plastic/garbage gyre bot and it failed and no mega-corp tried to save them.

if anyone should be forced to help on this effort, it should be amazon/bezos

Well, ycombinator is a place to change the world by incentivizing profit for doing so. Get some creative actuaries to run the numbers, sell satellite collision insurance, and fund a for-profit orbital janitorial service to improve profit margin on premiums.