The Kessler Syndrome Explained (2014) | Hacker News Reader

The Kessler Syndrome Explained (2014)

spacesafetymagazine.com

58 pointspmoriarty51 comments

>prepare to spend a few years without cell phone reception, Internet, and a five-day weather forecast.

Aside from the weather forecast the rest doesn't need any sort of satellite.

It's incredible how many people still think mobile phones are using satellites! It's a ground antenna, connected via copper or fiber to a wider network of... antennas. If you call abroad, 99% chances your call goes through a submarine cable which is again copper or fiber.

Same with Internet, unless you really are in the middle of the Amazon forest, or (live in country side in the states)

I still think there's lots of benefits to be had (and lots of money to be made) from replacing many of current satellites with high-altitude solar-powered UAVs. They'll be much cheaper to design and manufacture (no need for satellite-grade sterility, or engineering for microgravity environment), much easier to service and replace, and they'd offer some capabilities impossible for satellites (like not flying around the globe).

I've said that before, and got plenty of skeptical looks. I recently learned, however, that I'm not the only one thinking this - in fact the concept has been dubbed "atmosats", "pseudosats", or "HAPS". ESA seems to be into it now:

http://www.esa.int/Our_Activities/Navigation/Crossing_drones...

Have you heard of Facebook's Aquila drone? Sounds like something you are describing. https://en.m.wikipedia.org/wiki/Facebook_Aquila Also, Google's project loon comes to mind.

Yeah, they would both be good examples qualify.

I think some base stations use GPS time as time/frequency reference.

Many things need a precise time reference, which nowadays often comes from the GPS satellites. AFAIK, the 3G and 4G cell phone standards need precise timing to work correctly. Which means that "without cell phone reception" is a bit of an exageration; there's always the older 2G GSM standard. Same with the Internet, some networks might need precise timing to work correctly.

LTE and beyond require very precise timing. There are roughly two options for this. The first is you install a GPS antenna on every tower and synchronize time that way. The second is that you distribute the time to the towers over the backhaul network, typically using PTP (Precision Time Protocol) which would not be affected.

Additionally, GPS satellites are in Medium Earth Orbit (20k km up or so) and wouldn't be heavily effected by a Kessler Syndrome developing in Low Earth Orbit (160-2000 km up).

Weather forecasts would be affected, but it wouldn't be the end of them. There are still ground weather stations relaying their wealth of data.

Your Satellite TV wouldn't be affected either, since those come from Geosync Satellites (GEOs), which orbit at 35,786 km. Communications satellites like Inmarsat (L-Band), Ku, and Ka typically operate in GEO. Iridium would be fucked though.

The most heavily affected application would be Spy sats. They have to orbit close to the Earth for focal length reasons.

So a tragedy of the commons, like any other.

The best way to solve it would probably be to have all actors agree on some rules (no rocket bodies left in orbit etc) and some economic incentives such as "for every kg put in orbit you have to pay $X to a fund for the cleanup".

And just like with CO2, the countries responsible for the last 50 years of launches should prime this fund with money for past launches, because the countries that just started launching won't agree to the scheme otherwise.

So basically: US, EU and Russia pay billions to a fund in exchange for India and China agreeing to start paying for future launches.

There are rules for satellite designs in place and evolving to address this. You can't just leave things in GEO they must have been launched with a lifecycle plan and suitable fuel/propulsion to move to a dead parking orbit.

I think I heard of that too. But in order to improve these rules need to be extended to fund the cleanup (i.e. a fund for cleaning up any old debris + the fraction of satellites whose decomissioning doesn't work). Otherwise, the situation is slowly getting worse anyway.

Do you know if the rules also mandate that you can't leave fairings, rocket parts etc. in orbit?

For the most part, it really isn’t possible to clean up space debris. The fuel requirements are orders of magnitude too high.

Enforced by what bodies?

(Not trying to be cheeky, I really want to know. The primary problem here isn’t specifying rules but enforcing them among superpowers.)

At the moment, common consensus is strong enough. There isn't anyone who has the precise combination of the discipline and foresight necessary to have a functioning space program at all, and the lack of discipline and foresight to not care at all about Kessler syndrome, and/or not be directly impacted by it. It would seem to me to require a contradictory level of long-term thinking and lack of long-term thinking.

If a rogue actor (in the parlance of the age) managed to put together enough of a space program that they could make a few launches, but felt they personally had no stake beyond that, they could try to deliberately trigger the Kessler catastrophe, but at the moment I'm not aware of anyone who is there. (Even the gulf between suborbital missiles and true orbit is fairly large.) And it would have to be a truly rogue actor, not merely one sponsored by a superpower who does have an interest in the orbital space staying useful, e.g., North Korea and their complicated relationship with China, so not a puppet of the US, China, Russia, the EU, etc.

I wonder if there's a bit of a land grab going on right now to claim as much LEO and geosync spots as possible before they dry up and become too crowded to operate in safely. Maybe a secondary market of orbital slots will open up where current operators sell their huge chunks to new entrants. Just like good old ipv4.

There's not really a land grab, and you better be sure to have propulsion on board in the coming years, as youll most likely have to evade other defunct satellites.

The ISS is actually in a bad position, as satellites tend to go to earth, and the ISS is between earth and most LEO sats (400km vs 600-800km).

The ISS is in a great position, because it's in an altitude with such high drag that small objects and uncontrolled fragments deorbit very quickly. Even the ISS loses 50 - 90 m of altitude a day.

Satellites passing through the ISS's orbit do not tend to spend that many orbits there.

In LEO it's not about orbital slots - it's about frequency bands.

Claims on frequency bands in orbit are governed by the ITU; because of its international nature, there aren't agreed-upon policies for frequency assignments, so instead the rules are simple and competitive. The first entity to get a satellite in orbit using a specific frequency band gets the exclusive rights to that band, so there's a lot of pressure to get a symbolic bird up early to stake your claim.

GEO sats have been slot limited for decades. The birds need to be spaced roughly 1 degree apart in the sky to avoid the need for massive ground antennas to talk to them. A few birds get slotted in half degree slots, but they aren't popular.

You can have two birds share a slot if they operate on different bands (L vs. Ku for example), but there are basically only three popular bands currently in use (L, Ku, and Ka) and using a different one would mean custom designing hardware and negotiating with the FCC and nobody wants to deal with that. Ka is also a bit exotic currently, although it's way more widespread now than it was a few years ago.

This is why some of the biggest satellites we launch are GEO bound communication sats. They're like luxury condos in a high priced neighborhood. Because the land (orbital slot) is so expensive the developers want to make the most of it. Things can be a lot more amateur down in LEO where your freespace loss is so low you can talk to your bird over an omni antenna. There your bigger concern is just getting bandwidth on a usable frequency.

This is something I've wondered about when people start talking about capturing asteroids in Earth orbit and mining them. Mining is typically a dirty activity and most asteroids are more like a loose collection of gravel to begin with, and have such pitiful escape velocity that keeping them together is going to be a significant challenge. One high energy impact from an errant asteroid could make a tremendous mess in whatever orbit they are using, and to the extent that orbital mining makes sense at all it almost has to happen in LEO if you want to use the products on Earth or benefit from labor/equipment being launched from Earth.

You could plausibly get a nearby asteroid into a wide orbit of the Earth for 500 m/s of delta v. But getting it from there all the way down to LEO would take 3 km/s. So I expect most asteroid mining would take place fairly far out as a practical matter since the products of mining would be lighter and easier to move. The main downside would be days of travel time to and from the mining site. And there is a market for the products of asteroid mining in GEO in the form of commsats who might want to be refueled or someday maybe even have some parts make from asteroid stuff.

Refueling GEOs will probably never be profitable. They already last for 15+ years and are replaced by much improved satellites when they are retired. Keeping an old one running isn't worth it because the orbital slots they are in are too expensive.

IMHO, asteroid mining only makes sense if you are also manufacturing things in orbit (like spaceships and orbital colonies). All of these plans to deorbit the mined materials are crazy talk IMHO. Even if you find some amazing near solid platinum asteroid nearly in orbit already the costs of mining it and bringing the material back to Earth make it extremely difficult to compete against terrestrial mining.

If you are actually manufacturing stuff, then you are much more free to choose your orbit. You can even choose to orbit the moon instead to reduce the possibility of disaster.

So if North Korea launches one of their ICBMs into LEO with a billion metal pellets, would it be the end of the space age?

It might make things harder, but it probably wouldn't end it entirely. These humans we have here are remarkably ingenious, have a high risk tolerance, and would probably come up with some way of dealing with it.

And LOE still has some atmospheric drag, which means that debris will eventually fall to Earth. So that would be more of a "space age hiatus". By the way, we already have some ideas on how to deal with debris [0], so in the event of an actual Kessler Syndrome we could try them out.

[0]: https://en.wikipedia.org/wiki/Laser_broom

"Space age hiatus" would be a serious blow to our future as a species, though. It seems that over the last few years, all the necessary components required to bootstrap an economy in Earth's orbit / cislunar space have been coming together. This peculiar synchronization may completely collapse if we were to suddenly lose space access for couple of years (or decades).

It takes more rocket to launch into LEO than it does to get a ballistic trajectory to your nearest enemy. Your average ICBM doesn't have the oomph to do it. If it did, then it could target any point on the planet, and we are fairly sure the North Korea ICBMs can't do that. Yet.

Also, once you have got your pellets into LEO, you need a way to spread them with a variety of relative velocity. A satellite-satellite collision or a rocket explosion does this very well - the models give the individual fragments 1km/s relative outward velocity from the incident, so you basically need to make a nail bomb. Some of the fragments will be blown in the backwards direction, and may re-enter the atmosphere on the first orbit. Interestingly, because reasons, fragments that are blown upwards and downwards may also re-enter on the first orbit too.

You could actually get a payload into LEO with an ICBM, as long as it was lighter than your average nuclear warhead (or for MIRVed missiles, lighter than your warheads plus bus).

Could you? I mean if my KSP knowledge is anything to go by, yes you could, but KSP isn't reality and I can imagine the rocket itself is already too heavy or doesn't have enough thrust / fuel to bring itself into orbit.

KSP is close enough to reality here.

Also, isn't US fond of using old ICBMs to launch military satellites?

Usually just on the 4th of July (give or take a week)

It's considered a valid way to dispose of excess missiles under disarmament treaties like START.

We've used old ICBMs to get stuff to the moon. LADEE most recently.

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

The principles that KSP teaches are correct except for the bit where in KSP you're only under the gravitational influence of one body at a time, which doesn't matter for reaching orbit. The specific numbers in the KSP parts are totally fudged to make the game more fun but parts with those numbers would work like they do in KSP if they existed. For instance in real life jet engines have a lower thrust to weight ratio than rocket engines.

EDIT: But you can download the realistic solar system mod to get a sense of what real world thrust ratios and orbital delta-v is like. And Children of a Dead Earth has multi-body physics for Lagrange points and so on.

If you really want a realistic but still playable sim, there's also Orbiter which not only uses real numbers as much as possible, but actually goes so far as to model non-spherical gravity sources like lumpy asteroids.

Launch retrograde (in the direction opposite to the spin of the Earth) with low inclination, and spread the pellets around just a little; should be enough to deny everyone their typical launch trajectories and would also remove the need to shoot those pellets very hard - everything else will be running into them at 2x the orbital speed.

Launching retrograde means you have to make your rocket bigger. And once you are travelling at orbital velocities, a glancing blow is quite enough to cause catastrophic damage anyway.

A bigger rocket or a smaller payload, yes. Higher-energy collisions should produce more and higher-energy shrapnel, through, leading to even less predictable mess. Also, Inescapable Hypervelocity Shredder™ has a nice ring to it, and it would be giant "fuck you" to the rest of the world; precisely something you'd want to do if you were crazy and hated the West.

> precisely something you'd want to do if you were crazy and hated the West.

That assume the leadership is actually crazy and hating the west, though, rather than a mix of in a bind because their own propaganda has made a lot of their population expect a hard line against the west, and genuinely believing they are facing a threat.

To dig into history, Reagan by most reports reacted to the indications of the Soviet fear over Able Archer 83 [1] (where the Soviets may have come dangerously close to thinking the NATO exercise was a smoke screen for an intended first strike) with shock that they might have actually seen America that way. He later wrote in his autobiography (copied from Wikipedia):

> "Three years had taught me something surprising about the Russians: Many people at the top of the Soviet hierarchy were genuinely afraid of America and Americans. Perhaps this shouldn't have surprised me, but it did...During my first years in Washington, I think many of us in the administration took it for granted that the Russians, like ourselves, considered it unthinkable that the United States would launch a first strike against them. But the more experience I had with Soviet leaders and other heads of state who knew them, the more I began to realize that many Soviet officials feared us not only as adversaries but as potential aggressors who might hurl nuclear weapons at them in a first strike...Well, if that was the case, I was even more anxious to get a top Soviet leader in a room alone and try to convince him we had no designs on the Soviet Union and Russians had nothing to fear from us."

In other words: if your opponents seems to act irrational, it's worth considering that maybe it is because you don't understand their world view. If someone is threatening to nuke you left right and center, is it more likely they are crazy, or that their starting worldview has led them to a conclusion that they are under such dire threat that they have no other choice than to play up their capabilities as deterrence?

It is worth considering because the avenues to defend against a madman vs. a scared but mostly rational person are potentially very different. E.g. the latter is more likely to respond well to attempts at giving them reasons to feel safer.

(and as much as I dislike a lot of Reagans legacy, the above realisation was a large part of him changing tack on foreign policy towards actually talking to the Soviet leadership, and it made a huge difference, and he deserved praise for doing so instead of just blindly continuing to push the same aggressive line he started out with)

[1] https://en.wikipedia.org/wiki/Able_Archer_83

A similiar idea has been around since the 1980s. Put a cloud in retrograde geosync and within a few days there will be nothing functional left, just a mini-asteroid belt.

http://www.jamesoberg.com/pearl.html

How long would it take for orbit decay to bring these objects back into the atmosphere?

That’s one of the key factors. It depends on the how high the orbit of the satellite is. For ones in LEO

- below 350 km, months

- 400km a year

- 500km five years

- 600km ten years

- 700km twenty five years

Etc.

However, when a satellite breaks up, the small pieces are much more affected by drag. Another is effect is that an explosion results in approximately 50% of the pieces having a lower orbit. So even though the Cosmos-Irdium collision happened at 700km, which would take about twenty five years to deorbit, in just five years, more than a quarter of the debris had deorbited.

When you put it like that, it doesn't sound as bad as, say, nuclear winter. 25-50 years of high debris, then slowly reducing remains. It's weird to imagine that if humanity would die out suddenly, our satellites and orbital space waste would only stay up there for what, 100 - 200 years more?

GEO stuff would stay for much longer, though; it's 36Mm up.

Kessler Syndrome is very unlikely in GEO orbits. The reason is twofold: first the distances are enormous, but more importantly all of the satellites are traveling at the same speed in the same direction. Even a defunct satellite that didn't get put in a parking orbit and starts drifting will take years before it even has a chance of colliding with another satellite, and the odds of that collision are infinitesimal.

In LEO you have a completely different story. The distances are still large, but not as overwhelming as they are in GEO. Also, satellites are flying in every direction at very high relative velocities to one another. A piece of space trash could have thousands of potential collisions per day, so even if the odds of any one collision are small the cumulative odds start to add up over time.

Of course the other problem is that when we put people into space we put them in LEO. People have not ventured beyond LEO since the Apollo program. In the event of a full blown Kessler syndrome manned space flight would have to be put on hold for decades while we wait for the skies to clear up.

Only the stuff in low orbit. Communications satellites and the like in Molnya orbits or geosynchronous orbits will last millenia.

You are right - it's not apocalyptic.

Particularly, since satellites in general are getting much lighter than they used to be (faster decay times, less mass in case of a collision, smaller target), as well as targeting lower orbits than we used to (most go to 400km-500km now).

Also, even in the event of everything in LEO blowing up, we can still launch to farther orbits / other planets.

> Also, even in the event of everything in LEO blowing up, we can still launch to farther orbits / other planets.

It'd be risky though, since you have to cross LEO to get there (unless you're willing to pay the extra cost of launching to absurd inclinations and correcting in space).

It would take an unbelievably catastrophic Kessler syndrome to make it too dangerous to boost through LEO. It's not a game of Asteroids, we're talking about collisions on a yearly or possibly monthly timeframe. Bad enough to ruin LEO for satellites, but not so bad that it blocks you from space entirely.

I still think a believably catastrophic Kessler syndrome would be risky enough that NASA and others would refrain from sending manned missions through LEO at low inclinations.

It's not a game of Asteroids, but it's also not as thin as the asteroid belt.

How long can something stay in low earth orbit without propulsion?

Needs a (2014) tag.

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