[Jean-Papoulos]

From a comment :

>The first move in the coming WWIII, where the emperors try to expand their empires militaril,y will be to wipe out any orbit with Starlink satellites.

I find this highly unlikely, given Starlink is soon to reached 10k satellites and will continue to grow. Why expand 10 000 ballistic missiles to bring down one of many communications networks ?

[bell-cot]

If it's WWIII, and you're using ballistic missiles against satellite constellations, then either:

- You are not targeting individual satellites; you're setting off nuclear warheads in space, and relying on the EMP to disable all satellites within a large radius of the blast - https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse

or

- You're nuking the ground-based command & control centers for those satellites. Again, nothing like 10,000 missiles needed.

(Or both.)

To target 10,000 satellites directly, the "obvious" weapon would be a few satellite-launch rockets, lofting tons of BB's (or little steel bolts, or whatever) - which would become a sort of long-duration artillery barrage shrapnel in orbit.

[jeroenhd]

> - You're nuking the ground-based command & control centers for those satellites. Again, nothing like 10,000 missiles needed.

With Starlink's peer-to-peer capabilities, hitting every single ground station and keeping the satellites from working through new ground stations may actually be quite difficult.

Starlink orbits close enough that they're looking into offering LTE coverage from "space". You don't need a giant dish to access the satellites, which means building new ground stations and reprogramming the network from an unassuming-looking ground device to use them is quite feasible.

The paths of the satellites are rather predictable, though, so your shrapnel attack executed with some precision should clear out enough of them.

The moment you launch a nuke (even if just to set off an EMP), you can expect nukes to come your way in retaliation before your nuke even detonates. Unless whatever war is going on has already gone full nuclear, I don't think nuclear weaponry is a viable move to take out satellites.

[bell-cot]

> With Starlink's peer-to-peer capabilities, hitting every single ground station and keeping the satellites from working through new ground stations may actually be quite difficult.

Yes-ish? I was thinking the command & control facilities - far scarcer than the (probably unmanned) StarLink-to-Internet Backbone connection ground stations.

> The moment you launch a nuke...

Yes-ish. The (great-)^n grandparent comment posited WWIII starting, and the nukes flying at scale. Between the widespread obliteration of ground-side infrastructure, ground-side EMP damage, and very likely EMP in space - I'd assume that Starlink would quickly go down. Plus, the ionosphere could become opaque to Starlink's radio frequencies. Finally, the ionosphere's upper layers might expand enough (due to nuclear detonations in or near space) that the orbits of the Starlink satellites started degrading very quickly.

With how easily any major space power could set off "small n" nukes in space during a major crisis, to knock out satellites - I would not rule someone doing so. The responsible parties need not claim responsibility. And sane leaders might hesitate to go full nuclear in response.

[NetMageSCW]

The BB idea doesn’t really work either- if they are in orbit they circle with the satellites and don’t hit anything, if they are at different speeds they are in different orbits and fly above and below the satellites and miss, if they cross the orbit SpaceX just moves the satellites to miss.

[bell-cot]

"Circle with the satellites" is not how orbits work. Do a Google image search for satellite ground tracks, and observe how those tracks repeatedly cross each other. In LEO, a 90 degree orbital crossing represents a relative velocity of >10km/s. (Normally, collisions do not happen because the satellites are under control, and everyone is making ongoing efforts to avoid collision. Kinda like how cars & trucks normally don't hit pedestrians.)

BB's - https://www.amazon.com/bulk-bbs/s?k=bulk+bbs - run roughly 3,000 to the kg. And are far too small to individually track in orbit - https://clasp.engin.umich.edu/2023/12/06/tracking-undetectab...

Bottom line - a "3 tons to LEO" satellite launch vehicle could put ~10,000,000 untrackable little metal objects into orbit, crossing satellite orbits at lethal velocities. Trivial methods, such as dispersing the BB's with small explosive charges, could randomize their individual orbits.

The satellite operators have very good reason to be concerned about such "low tech" anti-satellite weapons.

[TOMDM]

Because Kessler syndrome means you don't need to hit all 10k yourself.

Lowering the orbits just means that we get back to normal faster, not that the it's impossible.

[JumpCrisscross]

> Kessler syndrome means you don't need to hit all 10k yourself

Kessler is useless for LEO constellations. The timeframes of the cascades exceed the useful lives and dwelling times at those altitudes.

I am not aware of a military solution to prompting a cascade over even a limited area. Instead, you’d use repeated high-atmosphere nuclear detonations to fry birds in a region.

[lijok]

Does Kessler syndrome also mean ICBMs become nonviable?

[Dylan16807]

No.

It's not a wall. The risk from going through a dangerous orbit is much much less than the risk from staying there.

[goku12]

That depends on how you define risk. If it means the probability of a collision, then you'd be correct. But if a collision does happen, the consequences will be worse than being in the same orbit. Based on an oversimplified model, debris in orbit is likely to have low relative velocities with respect to an intact satellite in the same orbit, since a large deltav would change the orbit. (It's not as simple as this, but it's good enough in practice.)

This is actually what asat weapons take advantage of. They usually don't even reach orbital velocity, just like ballistic missiles (of course, there are exceptions like the golden dome monstrosity). The kill vehicle just maneuvers itself into the path of the satellite and lets the satellite plough into it at hypervelocity.

[gpderetta]

I remember a short story about Canada preventing total global annihilation in WWIII, by deliberately triggering Kessler syndrome. My google-fu is failing me though.

[iberator]

I would love to read it:)

[NetMageSCW]

Stop trying to make Kessler syndrome a thing. Kessler syndrome isn’t a thing, and it will never be a thing.

PS The original paper expects the cascade to take decades to centuries. No one can afford to shoot down Starlink except SpaceX.

[pixelpoet]

Stop trying to boss people around, and just make your point with some citations.

[abdusco]

It's a reference to the "stop trying to make fetch happen" meme from the movie Mean Girls.

[pixelpoet]

Ah, so I should have replied with "Yeahhh bitch, science!", because that's a reference to the Breaking Bad meme? That's how we're discussing things now?

[Cthulhu_]

Or why try to shoot them down when you can also go to the command center and turn them off? Or do a targeted strike on said command center. The sattelites are plentiful and redundant, but the network will collapse very quickly when they're no longer controlled from the surface.

In fact, if SpaceX can no longer do any launches due to whatever reason, Starlink will no longer be feasible after a few year - if I'm reading it correctly, the sattelites have a lifetime of only 5 years, meaning they will have to continually renew them at a rate of 2000 new sattelites a year.

[tlb]

You could launch some missiles, blow a few satellites into smithereens, and gradually over the next few months they would take out the others. That's a poor kind of war weapon. An effective weapon is one where you can inflict damage continuously, and are able to stop immediately upon some concession. If you can't offer to stop in return for concessions, you won't get any.

[RealityVoid]

You don't take down satellites in order to force someone to negotiate, you take them down for denial of capabilities.

[panick21_]

Its not really that easy, to cause such a chain reaction, specially if the other person reacts.

And its also really expensive, each sat you take down costs you far more then what you hit. So unless you can actually cause a chain reaction its a losing proposition.

[ViewTrick1002]

Not really. That’s more science fiction than reality. You should try some Kerbal Space Program and explore how orbits are affected by thrust = collisions, in different directions.

As soon as a satellite is hit the rest of the fleet can start thrusting and raise their orbits to create a clear separation to the debris field.

Following such an attack the rest of the fleet would of course spread out across orbital heights and planes to minimize the potential damage done by each hit, leading to maximum cost for the adversary to do any damage. Rather than like today where the orbits are optimized for ease of management and highest possible bandwidth.

[LightBug1]

What was that game on old PC's? ... Minesweeper ...

[aucisson_masque]

You don’t need 10k missiles. You need just one to blow up all of starlink satellites.

This is like bowling, you hit one, it hits the other one etcétéras.

[NetMageSCW]

That is not how it works at all.

Imagine using a rocket and blowing up one car on a highway - how many other cars will actually be affected? How many cars on other highways will be affected?

[aucisson_masque]

https://en.wikipedia.org/wiki/Kessler_syndrome

[jdiez17]

You would likely need at least one per orbital plane, of which there are about 24.

[goku12]

Blowing up something in the same orbit as the targets isn't an effective strategy. The explosion disperses the fragments into different orbits that intersect the original orbit only at one or two points. And even if some of those fragments find their targets, the collision velocity will be low (relatively slow).

It will be like getting hit with with shrapnels from a grenade. Depending on how they collide, the target may survive. If you think that grenade shrapnels are fast, you need to understand the 'hypervelocity impact' that happens when objects in different orbits collide, or when an interceptor hits a satellite. Hypervelocity impacts are impacts where the impactor moves faster than the speed of sound in the solid target. What that means in practice is that the debris/interceptor may have hit one end of the satellite and vaporized already, while the other end of the satellite doesn't yet feel the shock and vibration from that impact. That end doesn't yet know about the carnage that's about to hit it in a few milliseconds.

[gehwartzen]

I imagine you could just send a rocket to the specific orbit and just start metering out 100s of thousands of small steel (or whatever) BBs like seeding a yard; seeding a Kessler event.

Something just a bit bigger than:

https://en.wikipedia.org/wiki/Project_West_Ford

[ben_w]

Looking at the price of industrial lasers, right now the only thing stoping a random 3rd world terrorist cell from being able to afford to destroy all of them is the adaptive optics to compensate for atmospheric turbulence.

Well, that and the fact that so much of the stuff on Amazon etc. that's listed as "welding laser" is actually a soldering iron.

[NetMageSCW]

I think you severely underestimate the amount of power you would need to damage some Starlink satellites in the 4 minutes they would be visible while tracking them at ridiculous speeds.

[ben_w]

Modern welding lasers are pretty powerful. Hard part is focussing them, especially given need for adaptive optics for atmospheric turbulence. Movement is almost irrelevant, they only deviate from a fixed path while their engines run, and even then those engines are pretty weak.

I'm saying the only real limit now is the adaptive optics.

[laughing_man]

When people attack satellites with lasers, what they're trying to do is blind surveillance sats. To actually physically damage a satellite would take enormous amounts of power and accurate tracking tied into powerful radars. That's something a state might do, but too many resources are involved for terrorists.

[impossiblefork]

I don't think that's necessarily true. I think with modern lasers the power to get permanent damage is there.

I don't think powerful radars are required either. The satellites will probably reflect the laser. At 4000 km this is 26 ms, so you would probably be able to use the laser itself for the adjustments.

[ben_w]

Previously, perhaps.

I'm saying the only limit to damaging them now is the optics.

Radar is pointless here. Both for crude and precise positioning. For crude, we already know roughly where the satellites themselves are because those are well-advertised.

For precise, you still wouldn't use radar, physics prevents high enough resolution ever. Even for tracking, angular resolution is k(λ/D), i.e. you care about aperture size in wavelengths, and radar uses wavelengths much much larger than visible or IR laser light. But even with arbitrarily large equipment, you get a spot size ~= wavelength, which wastes a lot of power as the wavelength is much larger than the necessary spot size for a critical component on a satellite.

So you'd use optical targeting and tracking, i.e. you'd look through the exact same system that the laser also fires through, with the exact same adaptive optics, and say "this specific point on this satellite".

The hard part is focussing a spot size order of cm scale (it can't be the same size as you find in a welding system for same reason radar is useless, k(λ/D) gets you ≥300m telescope and that's obviously a no). This requires adaptive optics (and also a wide telescope). Adaptive optics is the really hard part here.

Getting a 12 kW industrial laser is relatively easy, and putting that power into a spot on the joint between the PV and the main body, that has a decent chance[0] of weakening or severing it while also causing catastrophic loss of control, even with just a few minutes over the horizon. Weakening is still important, see all 9/11 memes about steel beams and why they miss the point. Severing is plausible but only because of space design constraints, see [0] again.

As I understand it, PV cells themselves have a much lower threshold for catastrophic damage, a 12 kW system is basically guaranteed to cause irreparable damage to that even in a few minutes even though the spot size here is much much larger than you'd find in a welding system.

The prices I see for 12 kW industrial lasers are significantly lower than the estimated cost per missile for most of what the Houthis used to attack shipping last year, and they fired quite a lot of those missiles.

[0] can't say for sure without detailed plans that it would be genuinely insane[1] for me to have access to; but do consider that everything in orbit is mass constrained, even with SpaceX pricing, and designed without expectations of e.g. wind or needing to support its own weight, so the thickness of structural elements is likely much lower than you'd expect from anything you see on the ground

[1] the world is currently going insane, so if it turns out they are available, either deliberately or via a leak, this is just more evidence of insanity rather than a contradiction