New Calculation Finds we are close to the Kessler Syndrome [video]

Is Kessler syndrome the Great Filter (https://en.wikipedia.org/wiki/Great_Filter)?

As in, is it the thing that makes it so no one else has broken out of their planet to come visit us?

I could totally see it being the case that as soon as a civilization gets good enough at putting stuff into space, they start putting a lot of stuff into space and then things start crashing into each other to the point that they can’t ever launch any more things into space and become stuck. Trapped by the artifacts of their own progress

I would guess that it would still be possible to send things beyond earth's orbit with only a low probability of collision with debris but perhaps I'm wrong.

"Low" is tough to say until someone does some proper sort of 'true mapping' of space debris in the range somehow. Protection would require a lot of complexity and cost due to the need for shielding and the delta-v to move it up there.

> until someone does some proper sort of 'true mapping' of space debris in the range somehow

You look at which satellites poofed and then figure out the maximum extent their debris could have drifted.

Every launch failure will result in more debris and even lower probability of a successful future launch.

That works a little bit when we're talking about one satellite poofing in a year based on a collision with another satellite, and not at all when we're talking about thousands of events a year, many of which are satellite-debris collisions too small to track (you only get one orbital vector), or between pieces of debris.

Every collision generates hundreds, maybe thousands of pieces of debris, only the largest of which are trackable.

Rather than protection on each rocket, couldn't you just send a bunch of fortified rockets that absorb the debris during a collision but don't emit anything. Do that a few times and then all other rockets just reuse the path that was cut?

Orbit is not a location. Orbit is a group of velocity-location vectors which form a stable loop around a body, without intersecting that body.

Imagine a bullet circling your head at mach 25. Now imagine a second bullet, circling your head at a slightly different angle, at a slightly different distance from your head. There's a chance that they could collide, and the resulting explosion would leave a great deal of dust... on a mixture of velocities, still circling your head. Now add a third bullet, also on a slightly different vector; Make sure that it doesn't collide with any of that dust!

The actual situation is we aren't dealing with 3 bullets or 100 bullets, we have ~170 million objects orbiting the Earth, and only around 50,000 are large enough to track. They are all moving fast enough in relation to each other that a collision would result in a sizable explosion, not an elastic agglomeration. We have no way of removing them.

The good news is that there is a large volume of space for them to exist in. The bad news is that as we continue to fill it up, odds of collisions increase, and every collision spawns many, many more objects.

You’ve explained what Kessler syndrome is but not why my idea doesn’t work.

I’m saying send reinforced rockets through the orbits that absorb the collision instead of generating more dust. That should let you clear a path through all orbits that intersect your path. It’s hard to do and the 3d aspect of it might make it expensive but conceptually it could be a solution. Or use super powerful lasers (potentially mounted on a satellite) to deorbit the dust

I'd consider it much less likely than e.g. nuclear or maybe chemical/biological warfare.

Kessler syndrome (if even achievable with current technology) would be a major bummer for science and the global economy for a couple of decades (no more Starlink, but we still have good old geostationary satellites, so no ships and airplanes would get disconnected as a result), or at worst centuries, but would otherwise not form any threat to civilization, whereas nuclear winter is already very capable of wiping it out.

No. The space junk at a given orbit makes it unviable to put more satellites in that orbit, but launching beyond that orbit is still viable.

It takes about 90 minutes to complete a low earth orbit. A rocket can't hover in place for 90 minutes at the same altitude, then increase its altitude by its height and repeat. It doesn't have enough fuel for that.

Not really. There are uncertainty bands. But based on the collision you know which orbits are spoiled for about how long.

> couldn't you just send a bunch of fortified rockets that absorb the debris during a collision but don't emit anything.

"Just" how? Orbital collisions happen at an average of 10km/s, you're going to make what, some kind of sponge that can get hit by a chunk of satellite going ~8x faster than a bullet and absorb it and slow it to a halt without fragmenting at all? Good luck.

> Do that a few times and then all other rockets just reuse the path that was cut?

Things in orbit are constantly moving, you can't "clear a path" any more than you can, IDK, make a safe route through a forest by walking through it once and moving any bears you encounter a couple of feet.

This doesn't work conceptually, but it's hard to explain without attaining a KSP baseline of understanding. https://xkcd.com/1356

"Clearing a path" is something you can do with a bulldozer through a traffic jam, but imagine clearing a path through a belt road by driving through the flow of moving traffic sideways at speed. Ultimately you can't hit every car in the outer lane with just one bulldozer, and the cars will close in and fill gaps because they're moving at slightly different speeds.

The easy elastic collisions you're imagining also just can't occur at these relative velocities. When something hits it looks more like an explosion than a "catch". If you shoot a local stone monument with high explosive artillery shells what happens? Does it reduce the number of things flying through the air or increase it?

I love this retort. Made my day.

> if even achievable with current technology

Launching a nail bomb into orbit would've been possible as soon as we were able to get into space, the only question is motivation. A terrorist state, say North Korea, threaten the rest of the planet and demand concessions once they're able to get any significant mass into orbit.

Go the other way. Attain maximum altitude and then descend slowly. You don’t need to do this with just one rocket. This would be a clearing exercise composed of multiple rockets.

How can you get past that orbit if there is all this junk destroying your rockets????

Ideally a satellite is in a given orbit for years. If junk is destroying it in weeks or even months you’ve got a massive issue.

However a rocket is spending in a seconds in that same orbit. Thus a rocket passing through may only have say 1:10,000 odds of a collision on its way to mars while satellites are getting shredded.

A large mass of Whipple shields.

The "clearing a path" idea is inane, but we do know how to absorb hypervelocity debris impacts while generating a net negative amount of debris.

I think it would be actually the other way around - Starlink orbits aee low enough to be self cleaning & Starlink satellites can be (and are) rapidly replenished. So even if something from up above hits anfew, the debris would deorbit soon & new ones could be launched.

With GEO sats, unless you go for direct GEO insertion, it might still have issues reaching the final orbit. And even at GEO, there could be a debris cloud as well causing issues, at least until the sun and moon gravity perturbs it enough.

This sounds like it would almost work in a 2D universe.

- "And even at GEO, there could be a debris cloud as well causing issues, at least until the sun and moon gravity perturbs it enough."

Not a satellite expert, but I understand GEO clears out relatively fast (~decades), because of those 3-body perturbations,

https://www.agi.com/blog/2020/07/geo-satellites-don-t-decay-...

> I’m saying send reinforced rockets through the orbits that absorb the collision instead of generating more dust. That should let you clear a path through all orbits that intersect your path.

No such material exists, nor can it be made from any matter that is based on electrons bound around a nucleus — the force of impact will break any such material.

> It’s hard to do and the 3d aspect of it might make it expensive but conceptually it could be a solution.

"expensive but conceptually it could be a solution" is also why we don't have an Orbital Ring instead of rockets: https://en.wikipedia.org/wiki/Orbital_ring

The cost requirement for getting something to space with enough momentum to do the cleanup, even if it was able to survive the impacts, would be comparable to the entire cost of getting the stuff constituting the mess into orbit in the first place: bad enough to be prohibitive even today with relatively little mess, much worse if there's an actual Kessler cascade.

> Or use super powerful lasers (potentially mounted on a satellite) to deorbit the dust

Could work for the bigger bits, but don't put the lasers on a satellite: 1) Power is short up there, as is cooling, much easier to put a bit laser on the ground and waste some energy going up through the atmosphere; 2) if you solve that constraint, you've now got an orbital laser that's an obvious and easy-to-hit target for all foreign powers to get upset about even if you didn't want to weaponise it.

For the smaller stuff, you can't see the dust to target it in the first place.

It really depends on how much junk actually is there and in what orbits; especially at 500 km up, space is big. The surface area of the earth is 510.100.000 square kilometers, at 500 kilometers the 'surface area' is a multiple of that (I can't math), surely there's enough gaps or lower-density areas at that height even if there was a catastrophic Kessler Syndrome event.

I'd say intentionally destroying space assets etc should be considered an act of war (compare attacking another nation's ship in international waters), NK wouldn't have a chance and they could be put into space lockdown where any launches are intercepted.

Whipple shields fragment, don't they? They slow stuff down enough to not be a hazard to the thing being shielded, but if the goal is mess-reduction I don't see how that will help?

https://www.researchgate.net/figure/Whipple-shield-concept_f...

integrate risk over time. if you have a high target orbit outside the "kessler belt" then you don't spend much time going through it. though this requires a fairly direct orbital insertion. slow orbit raising would have a higher risk, but even that would still be lower than for any satellite intended to operate for years and decades in an affected orbit.

The surface area at 500 km is 1.16 of the Earth surface area.

Good luck dragging people into war over space trash that doesn't even benefit most peoples' lives in any material sense.

The force of the impact effectively vaporizes part of the shield and the debris. Eventually the shield will be structurally unstable swiss cheese, but that can be modeled and the shield deorbited before it starts to fall apart.

On the other hand, there is just so much less stuff up there, as reaching that orbit is much more expensive in terms of energy expenditure, and it's all moving in pretty much the same direction and in the same orbital plane.

So unless somebody maliciously launches e.g. a bunch of ball bearings in the same orbital plane but opposite direction, the chances of "wrecking GEO" seem much lower (although the consequences would, as you say, probably be much more severe and long-term).

Are you sure that you have never looked at a weather forecast (or received a severe weather warning), crossed an ocean in an airplane, used GPS (or another satellite-based navigation system, or eaten food farmed using precision automated equipment that does), which are just the first things coming to mind that would be much harder without satellites?

Thanks for the explanation.

So you don’t think the 1:10k odds compounded over every space launch are enough to be a problem?

I was thinking that maybe as you get to a scale where you have things coming and going all the time, and each time they have to pass through the debris layer, and if they have bad luck they become part of that debris, that eventually you get to a point where even just passing through that layer is untenable. But you don’t think that is likely even for a society sending out interplanetary vessels every day?

A problem, but not an insurmountable one.

Being hit isn’t the same as being destroyed, you can track and avoid large objects, and small are survivable in the short term. https://en.wikipedia.org/wiki/Whipple_shield Collisions however keep adding up until a satellite fails.

Second an outbound rocket need not be in orbit, so if it is destroyed that may not result in extra orbital debris the overwhelming majority of mass could fall back to earth.

Also, Kessler syndrome isn’t a forever thing. There’s a reason planets have rings not debris clouds. It’s possible to have a steady state where the rate you’re making it worse is balanced with the rate things are naturally clearing.

Your link talks about how this is an unexpected result, and only occurs at specific inclinations.

It's new information to me, though. Thank you.

It is even worse than the analogy, because every bit of mass from that sunken ship becomes drifting naval mines.

The approximate-GEO belt involves far fewer satellites than projected megaconstellations, in a far larger volume of space, travelling at far lower orbital velocities, with a much tighter orbital plane distribution (so even lower relative velocities). Their orbital planes intersect every 12 hours instead of every 0.75 hours.

Targeted space junk disposal in GSOs appears to be quite practical. The easiest major orbital changes for an SEP stage to burn, structurally, involve lowering periapsis from high orbit.

Do you really think people will want to go to war to protect America's hegemony of gps?

I believe the US would almost certainly go to war if there were an intentional attack on GPS.

Yes exactly ... This is a cloud of junk that stops anything getting out....

The us goes to war if someone sneezes.