To be honest, I don’t have a good grasp for what it would take to trigger a Kessler cascade that could destroy a 12,000 satellite constellation in a reasonable amount of time.
I was going to write a Kessler-Syndrome triggering attack into a story I was writing, but my research indicated at the timne that even after a cascade starts, it takes years or even decades to clear LEO of satellites. Even a full Kessler syndrome wouldn’t stop us from going through LEO, because the time between collisions and the risk of a collision at any given time is still very low.
I’d be happy to hear it can happen faster. My idea was missiles filled with plain old gravel that would fly into LEO then spin up to the point where scribed weakness lines would fracture and spit millions of bits of gravel into LEO. Repeat for probably hundreds of missiles. But I really can’t tell what short-term effect that would have, or how much crap you’d have to put into orbit to trigger the Kessler syndrome.
But I would think that if the Chinese launched a bunch of missiles that started a cascade that would take even a month or two to develop, that would give the enemy a window during which it would destroy China’s conventional satellites with ASAT, then attack them before losing your own satellites.
A ‘natural’ Kessler Syndrome initiated by a single incidental collision between two spacecraft will probably take many years to escalate to the point of making an orbit incapable of being occupied because the debris field is probably narrow and it will take a while before collisions are frequent enough to accelerate up the exponential curve. Although the probability of occurrence in any given year is low, most experts in orbital debris analysis now think this is almost inevitable in the next ~150 years based upon Monte Carlo simulations and projections of orbital populations. Even though the US government-sponsored launches (and most other Western nations) are now committed to Orbital Debris Mitigation Standard Practices (ODMSP), there is just too much junk already in orbit that can interact with the increasing number of spacecraft that are inserted to avoid debris generation, and once a sufficient threshold of debris builds up there is nothing to stop the Kessler process from escalating.
However, a deliberate Kessler Cascade, engineered to produce a massive amount of debris across a large swath of orbital space would instantaneously escalate up the exponential curve, essentially producing many orders of magnitude more debris than would be expected ‘naturally’ over many years or decades. The fact that SpaceX (and other aspiring LEO telcom operators) have or will have many thousands of satellites orbiting well above the threshold that will naturally ‘retire’ satellites in a few years due to thermosphere drag makes this even worse, not better; once there are enough impacts to produce a wild field of debris, it is inevitable that the cascade will accelerate, and the large a population of spacecraft there are, the more mass there is to produce new cascades of debris.
I don’t have a simplistic ‘cite’ to offer you because these analyses are statistical simulations which rely on a bevy of assumptions, so there isn’t a singular, trivially digestible conclusion. However, if you look through the literature on Kessler cascades you will see how rapidly they can grow once the volume and spread of debris hits a threshold, so attacks designed and distributed to intentionally achieve that threshold will basically ‘move up the curve’ to the point that they accelerate the process. I will say that I spoke to a now retired JSpOC debris analyst several years back who was apoplectic about the scale of the Starlink distribution, and was concerned about the overall vulnerability of orbital space in the 500-600 km altitude to a deliberate attack, a point that has clearly not been missed by analysts of Chinese space defense (linking to the Gizmodo article because while it is not primary source it has links to translations and archived papers). Far from being invulnerable due to quantity, the Starlink constellation actually increases teh consequences of an attack, because even if an adversary cannot take down thousands of satellites with individual attacks, they can create a cascade that makes large volumes of orbital space unusable.
The point isn’t that Chinese (or another adversary) could destroy US assets, be they commercial (Starlink/Starshield) or military (SBSS, XSS, STSS, et cetera) while maintaining their own space resources, but that they could essentially eliminate a capability across the board that the United States military is highly dependent upon, and they are not. It is a ‘leveling the field’ maneuver that would favor them, particularly in ‘home waters’ and substantially limit battlefield intelligence for the US Navy and other military branches. That it could also escalate to a broader war is a concern held by many military planners and especially to advocates of trying to limit direct conflict in space, but it may be inevitable if the Chinese feel that they have no other choice.
Following a major ASAT attack be it direct sniping assault on our vehicles or the shotgun-like consequences of a Kessler Cascade, the US is not capable of rapidly reconstituting its space-based assets even if the orbits they would be reconstituted into were magically swept free of debris. We just don’t have the standby satellites, nor the launch capability. It’d be the work of decades to rebuild. Assuming magically free orbits to return to.
In loose metaphor, our satellites represent a weird sort of “fleet in being” made of tissue paper. It’s out there cruising around all day making other countries nervous. And cruising within range of their weapons. But if it gets “sunk”, it’s gone for good. Traditional “fleets in being” got their power from sitting safely in port. And thereby became too valuable to use or to lose. Our sat fleet is also too valuable to lose. But we don’t have a safe harbor to park it in.
Separately, but related …
I think it would be be a pretty tough sell to the US public to open real kinetic hostilities against China or Russia over the loss of a bunch of milsats with zero loss of human life and zero observable consequences on the ground.
If they took out the GPS constellation, that would cause a bunch of chaos in civilian life. But much of the rest of DoD’s alphabet soup of “birds” could be disabled before the public saw any impact on their lives. They’d be skeptical it’s time to start WW-III.
Both of my points amount to advantage for the US pre-conflict, and advantage for adversaries once they attack the sats. That is a classic example of crisis instability. Which is the opposite of what you want in order for peace to prevail through the inevitable provocations and misunderstandings and shifting rivalries.
But do you really need to destroy 12,000 satellites to knock that system out? I’d think a lot less damage would degrade the system to be useless (or near enough).
Those can be very dangerous too…
But that (and Fermi, and the Dark Forest) are side topics which should spin off into another thread for any further discussion… sorry for the digression…
That’s a good point. Degrading the constellation would certainly affect bandwidth and might cut some areas off.
However, Starlink is being used militarily today, and it’s got only a tiny fraction of its final constellation in orbit. So you’d probably have to destroy a significant percentage, but perhaps not all of them.
People have been working on redundant network architectures and protocols for quite a long time now.
Packet switching (IP protocol) and adaptive routing (CIDR) etc etc.
If the system is properly designed, I would expect it to be very robust.
Bandwidth might degrade, but you would probably still have connectivity.
ISTM the big question would be how the Starlink satellite-to-satellite links work.
It’s logically a mesh network. There are both highly directional RF links and extremely directional laser/optical links between satellites. But each link has a finite range. Destroy enough satellites in an area and a still functioning one might have nobody within range to talk to. Do that enough to the whole assembly and the unified constellation collapses into a collection of mutually isolated groups of satellites that can talk intra-group, but not inter-group.
I also wonder if any given satellite has the complete up-to-date enough ephemerides of the entire constellation. Which suggests they could have the situation of a satellite being in-range of another satellite, but unaware of the other’s existence or position, so it can’t aim its directional signal at that potentially-reachable target.
Be interesting to know the whole truth. I’m sure somebody at SpaceX has done the work, but they’re sure not telling.
I don’t know enough about the architecture to make a good asessment. Though presumably they must have a number of ground stations which could add redundancy?
By the way, do Starlink satellites have laser optical communication? I thought that was still experimental, according to NASA? Of course it’s an obvious way to transmit high bandwidth data (wave of the future, as it were)…
I don’t think they even had satellite to satellite laser comms in their V1 satellites, so the system can work okay without them, but it’s the satellite lasers that given Starlink a speed advantage over ground links because signals move faster in vacuum than in fiber.
Space based optical crosslinks have been around for almost 20 years and optical comm to/from LEO has been demonstrated many times over a similar time period. The article you link to is for deep space communications, which requires sophisticated sensors capable of capturing a signal consisting of a handful of photons. (which have been available for about 15 years).
from the article:
While optical communication has been demonstrated in low Earth orbit and out to the Moon, DSOC is the first test in deep space. Like using a laser pointer to track a moving dime from a mile away, aiming a laser beam over millions of miles requires extremely precise “pointing.”
US carriers would certainly be vulnerable in a China-Taiwan war, but IMO the US submarine fleet is miles ahead of the Chinese submarine fleet in technology and experience, and I think they could make it impossible for the Chinese to execute any sort of amphibious landing in Taiwan. Maybe they could get some paratroopers and other airborne troops into Taiwan, but even those would be vulnerable to Taiwanese air defenses. And it probably couldn’t be nearly enough to take the island anyway.
I honestly think the risk of China invading Taiwan is relatively low. I think China’s modern modus operandi is to win through constant pressure, subversion of Taiwanese politics, carrots and sticks, etc. The belt and road initiative is more China’s style these days. Economic imperialism learned at the feet of America.
The reason I’m not totally sure about this is that China is facing some serious economic and structural headwinds, and desperate countries do desperate things.
I’m not sure that really makes a lot of difference? The signal has to get from ground to satelilte and back by microwave; does one hop in the middle make such a change? And AFAIK propagation speed in fiber is not that much slower than C?
Propagation speed in fiber is roughly 70% of C, as I recall, because of the required internal reflection pathways. So yeah, it makes a big difference if you can make long distance hops in space. Such a big difference that Starlink is basing some of its profit potential on highly lucrative high speed trading links from overseas to the NYSE. A Starlink connection can beat undersea fiber by a number of milliseconds, adn in high speed trading that matters.
In absolute terms, you are right. I remember trying to access the Internet on a ferry across the English Channel some years ago and it was slow as shit, presumably because it was connecting via satellite in those days before anyone had really tried to put any infrastructure in place.
On the other hand: bandwidth vs latency… how important is latency for most applications?
Market trading, sure.
Military communication maybe? A few tens of milliseconds won’t matter in human combat, but I suppose if you are teleoperating a drone…?
But we are getting a bit off topic from the OP here, perhaps we should spin off to another thread about communications in various applications?
See the discussion above (specifically Posts #4 and #40) regarding Chinese naval capability and the adverse operating conditions in the East and South China Seas); there is no way for the US Navy to utilize its relatively small number of fast attack subs in the US Pacific Fleet to stop a full scale invasion of Taiwan without exposing them to far too high chance of counterattack, which for a ~US$4.3B asset (in FY2023 dollars for the Virginia class submarine) is nothing to be brushed aside. At best, they might be used as standoff launch platforms for BGM-190 Tomahawk cruise missiles, but the Arleigh Burke-class destroyer and older but still quite capable Ticonderoga-class cruiser can carry 3-6 times as many Tomahawks as well as anti-ballistic missile and anti-submarine defenses, and can travel in expeditionary support groups that will reinforce their defenses.
If anything will put pause to consideration by China for an invasion of Taiwan, or stop an invasion in its tracks, it is that the ROCAF has over 200k active strength with another 2.3M reservists as well as civilian militias, a strong defense posture that is essentially on constant alert, and the reality that trying to ferry troops and supplies across the Taiwan Strait to support an invasion would be logistically challenging in the face of even light resistance. It is doubtful that such an invasion would be more than transitorily effective, and the PRC would stand to gain very little as the Taiwanese have made it clear that they would prefer to leave a scorched earth rather than hand over any industrial infrastructure over to mainland Chinese authorities.
On the scale of internet communications and streaming bandwidth, those milliseconds matter a lot. But in military C3 (command, control, communications) so does resilience (survivability and responsiveness) and integrity (reliability, survivability, and interoperability). Starlink is a commercial system, built from commodity hardware to the expectations of normal business standards. Military communication systems will give up a little bit of speed and accept a certain amount of latency in order to assure reliable, unimpeded communications. And, again, Starlink is used as an open network for non-critical applications; it is in no way integrated into C3-dependent weapon systems or tactical control networks, nor could it be quickly or reliably ‘jury-rigged’ into service for those applications.
Do they really? Surely rapid response systems like anti-missile defences are not Internet-based.
The Internet (or a military parallel) may be essential for communications and co-ordination, but probably not at a millisecond resolution?
