The current trajectory is that SpaceX proved the commercial and military viability of an LEO megaconstellation, repeatedly lowering their target altitudes and raising their satellite count because of debris and cell size concerns...
And now the rest of the world is trying to catch up in a sort of arms race, and not taking any care about debris concerns. The most tempting orbits are the ones in upper LEO that permit them to launch fewer satellites.
SpaceX are going to end up well under 500km (orbital lifespan: a decade) before things are finished, and they switched to very low orbit staging with SEP spiral out to reach final orbit a ways back.
China's newest constellation Thousand Sails is at an altitude of 800km (orbital lifespan: thousands of years), with a thousand satellites in the works over the next year or so and 14,000 planned, and they're launching them using chemical upper stages designed to explode into a thousand pieces at the target altitude. This is sufficient for Kessler Syndrome all on its own, without counting interactions with anything else up there. A catastropic debris cascade at 800km percolates down to lower altitudes over time and impacts.
We need viable treaties limiting development beyond 400 or 500km and we need them ten years ago.
I don't know how to sell the urgency of this predicament. You can have as many satellites as you want, a million uncoordinated bodies, at 400km because direct collision potential scales with (satellite count / orbital lifespan) ^2 . At 1000km, satellites decay so slowly we are already too crowded; we have already overused the space. We are speed-running the end of the space age and we are doing it to save a small number of dollars and to avoid a small amount of diplomacy.
This is not something we get a do-over on. There is no practical way to collect ton-scale debris at present, no way to track kilogram-scale debris, no practical way to shield pressure vessels against gram-scale debris, and even milligram-scale debris can hit with the force of a bullet. After collisions start occurring at a rapid clip, the mass of potential impactors quickly forms a long tailed lognormal distribution that denies us space for centuries.
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'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.
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.
> don't know how to sell the urgency of this predicament
We need to start by understanding it. I'm having trouble finding this paper right now. But to date, all calculations have shown that Kessler syndrome as a generalised phenomenon is incredibly hard to trigger. Even intentionally. Especially in LEO. (Intentionally triggering it is of interest for strategic ASAT denial.)
> the mass of potential impactors quickly forms a long tailed lognormal distribution that denies us space for centuries
No, it denies certain orbits. (Again, barring some new orbital dynamic haven been discovered by this paper.)
If 800km impacts go asymptotic, it pollutes 700km and 900km orbits by virtue of having a distribution of resulting debris velocity vectors, and as drag pulls down all the resulting debris over the next thousand years, the 800km debris becomes circular 700km debris, and then circular 600km debris, and then circular 500km debris.
We are currently in a low-trust, selfish world where all hope of collaboration has gone out of the window, so we are on an unchangeable trajectory towards things like Kessler Syndrome and climate hell.
Why would any of the US' adversaries agree to that? We have SpaceX, and they do not; lowering the altitude of megaconstellations is asymmetrically far more costly for them then it is for us.
Stopping China's (highly strategic, military) satellite constellations isn't a "small amount of diplomacy". It's an impossibility.
(It's even their declared planning that deliberate Kessler cascades are on the table [0]—to try to ground this discussion in diplomatic reality).
Invite them in. Launch their satellites for them, at 400km. Give them cash or territory. Give away the farm. How doesn't matter. What matters is that we start coexisting at 300-500km, and we mutually taboo launching large amounts to altitudes much higher than that.
There is no stable Mutually Assured Destruction Nash equilibrium here, if either of us does this thing it causes dramatic harm to both.
Not regarding that as a worthwhile goal is "mineshaft gap" thinking - a zero-sum mentality entirely ignoring our collective advantage in order to pursue competitive advantage.
It is perfectly feasible to run a Chinese constellation alongside Starlink sharing the same space, orbitally. Very low orbits are self cleaning.
I think OP is suggesting US concede to sharing 500km orbits that SpaceX has disproportionately squatted rights to, since current international law is first come first serve. Where concede is to rejigger international law to increase density of 500km so others wouldn't have to go higher, i.e. PRC mega constellations going ~800 because ~500 mostly taken. Or in ops suggestion, free for all. This is more costly for US since it saves entrants from going extra 300km, but imo proximity also greatly enhances chance for friction... i.e. if everyone chilling around same plane, and it's going to get magnitude more croweded, expect a lot more overt/hidden space war assets there to trigger kessler.
basically, it sounds like the U.S. should not treat China as a competitor and we should cooperate. this insane hypercompetition for literally no reason (other than US capitalists wanting to remain dominant) is going to destroy us all.
Yes. In a lot of historical spaceflight programs, the stage used in the upper atmosphere stayed with you to the final orbit, and was detached at low speed there. This saved you from having to design your satellite with significant onboard propulsion. Some of the upper stages were able to vent remaining propellants or pressurants, some were allowed to heat up until the pressure vessel exploded.
Suffice it to say this is not sustainable for megaconstellations in thousand years orbits. The responsible thing to do with that kind of scale involves reliable, redundant, prompt de-orbit of upper stages, and ideally for high-thrust, high-mass, high-engineering-margin-of-error atmospheric upper stages never to make it that far into the mission.
One way is for the the US to be more politically stable again (some how). Every country with an army will want its own star link now for trust reasons.
The US is politically stable already (by historical and international standards), and has been since 1865. If you ignore the rhetoric and focus on actions there has been very little substantiative difference in foreign policy across the last 7 presidential administrations.
>I don't know how to sell the urgency of this predicament. You can have as many satellites as you want, a million uncoordinated bodies, at 400km because direct collision potential scales with (satellite count / orbital lifespan) ^2 . At 1000km, satellites decay so slowly we are already too crowded; we have already overused the space. We are speed-running the end of the space age and we are doing it to save a small number of dollars and to avoid a small amount of diplomacy.
This sounds like the most first-world-problem ever. It realistically affects practically nobody alive, nor would it ever. Most people will live and die on the planet's surface and never visit space, nor do they need to. There aren't too many space-based services that are really necessary to life on earth. Nobody really needs internet in the middle of nowhere. Sure, it's nice to have, but that's a first world problem that few people have.
Having satellites orbiting the planet is more beneficial than just solving the first-world problem of “knowing where you are” or “having Internet”.
NASA has done a large amount of work to use satellite data to forecast and then work to improve agricultural yields covering the entire planet. It definitely isn’t necessary, but to dismiss the improvement that has been made is crazy, and I’d hardly call “feeding people around the world” a first-world luxury given by space travel.
It adds to a pretty large body of literature around this subject, the gist of which is "risk is going up, but we don't really have a good way of estimating what that means in terms of actual collision rates".
As long as it is militarily and commercially viable then the number of satellites will continue increasing, regardless of what academics have to say about collision rates. As per usual this is a coordination problem and in case people have not noticed nations are becoming less coordinated and more insular.
> in case people have not noticed nations are becoming less coordinated and more insular.
And what is your yardstick for measuring this? As far as I can tell this is the opposite of true. It's a popular national news meme but I don't believe it's been measured in any reliable way.
I won't comment on the broader point about how insular countries are becoming, but on this specific topic I'd say that the international reaction to global warming, which appears to be a very similar situation, shows exactly how little action is likely to happen.
What would zapping a satellite with a laser achieve? I suppose if you get it hot enough to melt everything, without anything flying off, then it would turn into a spherical drop of molten scrap... but then what?
You ablate part of it on the prograde side to create a small retrograde thrust which will deorbit it.
I think the right move is to merge this approach with goo blobs. We launch a large goo blobs or nets into a few strategic geostationary orbits and now you only have to ablate objects so they hit the goo then deorbit the goo once it is full (or just leave it there) as they would be large known orbits.
My understanding was always that LEO is much less of a Kessler risk due to atmospheric friction - ie: in the absence of active control and regular correction, LEO objects will gradually de-orbit themselves. It's the the higher geostationary orbits that pose the problem.
Depends on where in LEO. Explorer I had a perigree of about 350km and lasted for 12 years, though the orbit was highly elliptical. 900km and above is stable for thousands of years and well within the (circular orbit) LEO ceiling of 2000km.
The parallels to global warming appear to be close enough that this could be a good area to study what actually changes behavior on a global scale for a global environmental problem. I suspect this is easier to 'fix' mainly because there are fewer entities involved so not a total parallel, but it still might be informative to see when in the crisis arc action actually starts happening and what messaging impacted that timing.
VLEO/LEO is the safest place to put satellites is it not? They'll eventually deorbit themselves if you do nothing, no?
The worst place for space junk is high orbits it would seem like. Earth was wildly visited by an Apollo rocket stage a few years back! That is pretty wild.
I would think newer sats will have collision avoidance capabilities and older ones will just crash. Maybe even clean up sats will be developed to collection them
Satellites fail (lost control, or spontaneously explode). Very small debris is everywhere and under 5-10 cm largely untracked, but some are working to fix this gap.
There is no incentive large enough for cleanup (it's expensive, nobody can/wants to pay, and there are a lot of objects)
Leo starts at 7.8 kilometers per second and speed plus secondary and subsequent collisions with very small debris makes it impractical. Also carrying fuel to react frequently would dramatically change the entire mission.
If your non refuelable sat is good for 6 months it probably no longer makes sense to launch it.
Positioning a large, armored satellite in low or mid-Earth orbit significantly enhances its strategic value for both offensive and defensive anti-satellite operations. Such a platform could serve as a pivotal asset in maintaining orbital dominance, offering rapid response capabilities to neutralize threats and protect critical infrastructure.
In other words, welcome various "death stars" to keep order against malicious Kessler style attacks, etc.
That helps nothing on the civilian side. Blowing up a sat will do nothing but raise long term risk.
Some sort of platform that can launch 'space drones' to deorbit a dead satellite before it crashes or if something else would happened to cause a collision, that could be useful, but, probably expensive.
The current trajectory is that SpaceX proved the commercial and military viability of an LEO megaconstellation, repeatedly lowering their target altitudes and raising their satellite count because of debris and cell size concerns...
And now the rest of the world is trying to catch up in a sort of arms race, and not taking any care about debris concerns. The most tempting orbits are the ones in upper LEO that permit them to launch fewer satellites.
SpaceX are going to end up well under 500km (orbital lifespan: a decade) before things are finished, and they switched to very low orbit staging with SEP spiral out to reach final orbit a ways back.
China's newest constellation Thousand Sails is at an altitude of 800km (orbital lifespan: thousands of years), with a thousand satellites in the works over the next year or so and 14,000 planned, and they're launching them using chemical upper stages designed to explode into a thousand pieces at the target altitude. This is sufficient for Kessler Syndrome all on its own, without counting interactions with anything else up there. A catastropic debris cascade at 800km percolates down to lower altitudes over time and impacts.
We need viable treaties limiting development beyond 400 or 500km and we need them ten years ago.
I don't know how to sell the urgency of this predicament. You can have as many satellites as you want, a million uncoordinated bodies, at 400km because direct collision potential scales with (satellite count / orbital lifespan) ^2 . At 1000km, satellites decay so slowly we are already too crowded; we have already overused the space. We are speed-running the end of the space age and we are doing it to save a small number of dollars and to avoid a small amount of diplomacy.
This is not something we get a do-over on. There is no practical way to collect ton-scale debris at present, no way to track kilogram-scale debris, no practical way to shield pressure vessels against gram-scale debris, and even milligram-scale debris can hit with the force of a bullet. After collisions start occurring at a rapid clip, the mass of potential impactors quickly forms a long tailed lognormal distribution that denies us space for centuries.
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
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.
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.
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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.
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> don't know how to sell the urgency of this predicament
We need to start by understanding it. I'm having trouble finding this paper right now. But to date, all calculations have shown that Kessler syndrome as a generalised phenomenon is incredibly hard to trigger. Even intentionally. Especially in LEO. (Intentionally triggering it is of interest for strategic ASAT denial.)
> the mass of potential impactors quickly forms a long tailed lognormal distribution that denies us space for centuries
No, it denies certain orbits. (Again, barring some new orbital dynamic haven been discovered by this paper.)
If 800km impacts go asymptotic, it pollutes 700km and 900km orbits by virtue of having a distribution of resulting debris velocity vectors, and as drag pulls down all the resulting debris over the next thousand years, the 800km debris becomes circular 700km debris, and then circular 600km debris, and then circular 500km debris.
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We are currently in a low-trust, selfish world where all hope of collaboration has gone out of the window, so we are on an unchangeable trajectory towards things like Kessler Syndrome and climate hell.
Humanity is a failed species. The engineers were right to send the xenomorphs.
Why would any of the US' adversaries agree to that? We have SpaceX, and they do not; lowering the altitude of megaconstellations is asymmetrically far more costly for them then it is for us.
Stopping China's (highly strategic, military) satellite constellations isn't a "small amount of diplomacy". It's an impossibility.
(It's even their declared planning that deliberate Kessler cascades are on the table [0]—to try to ground this discussion in diplomatic reality).
[0] https://www.scmp.com/news/china/science/article/3178939/chin... ("China military must be able to destroy Elon Musk’s Starlink satellites if they threaten national security: scientists")
Invite them in. Launch their satellites for them, at 400km. Give them cash or territory. Give away the farm. How doesn't matter. What matters is that we start coexisting at 300-500km, and we mutually taboo launching large amounts to altitudes much higher than that.
There is no stable Mutually Assured Destruction Nash equilibrium here, if either of us does this thing it causes dramatic harm to both.
Not regarding that as a worthwhile goal is "mineshaft gap" thinking - a zero-sum mentality entirely ignoring our collective advantage in order to pursue competitive advantage.
It is perfectly feasible to run a Chinese constellation alongside Starlink sharing the same space, orbitally. Very low orbits are self cleaning.
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I think OP is suggesting US concede to sharing 500km orbits that SpaceX has disproportionately squatted rights to, since current international law is first come first serve. Where concede is to rejigger international law to increase density of 500km so others wouldn't have to go higher, i.e. PRC mega constellations going ~800 because ~500 mostly taken. Or in ops suggestion, free for all. This is more costly for US since it saves entrants from going extra 300km, but imo proximity also greatly enhances chance for friction... i.e. if everyone chilling around same plane, and it's going to get magnitude more croweded, expect a lot more overt/hidden space war assets there to trigger kessler.
basically, it sounds like the U.S. should not treat China as a competitor and we should cooperate. this insane hypercompetition for literally no reason (other than US capitalists wanting to remain dominant) is going to destroy us all.
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> upper stages designed to explode into a thousand pieces at the target altitude
By this do you mean at the 800km altitude?
Yes. In a lot of historical spaceflight programs, the stage used in the upper atmosphere stayed with you to the final orbit, and was detached at low speed there. This saved you from having to design your satellite with significant onboard propulsion. Some of the upper stages were able to vent remaining propellants or pressurants, some were allowed to heat up until the pressure vessel exploded.
Suffice it to say this is not sustainable for megaconstellations in thousand years orbits. The responsible thing to do with that kind of scale involves reliable, redundant, prompt de-orbit of upper stages, and ideally for high-thrust, high-mass, high-engineering-margin-of-error atmospheric upper stages never to make it that far into the mission.
One way is for the the US to be more politically stable again (some how). Every country with an army will want its own star link now for trust reasons.
For how long?
Because this thing is happening right now, it's happening fast, and it's happening without any effort to fight against the trend.
If your answer is "let's revisit this in 2050", then it isn't an answer.
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The US is politically stable already (by historical and international standards), and has been since 1865. If you ignore the rhetoric and focus on actions there has been very little substantiative difference in foreign policy across the last 7 presidential administrations.
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>I don't know how to sell the urgency of this predicament. You can have as many satellites as you want, a million uncoordinated bodies, at 400km because direct collision potential scales with (satellite count / orbital lifespan) ^2 . At 1000km, satellites decay so slowly we are already too crowded; we have already overused the space. We are speed-running the end of the space age and we are doing it to save a small number of dollars and to avoid a small amount of diplomacy.
This sounds like the most first-world-problem ever. It realistically affects practically nobody alive, nor would it ever. Most people will live and die on the planet's surface and never visit space, nor do they need to. There aren't too many space-based services that are really necessary to life on earth. Nobody really needs internet in the middle of nowhere. Sure, it's nice to have, but that's a first world problem that few people have.
Having satellites orbiting the planet is more beneficial than just solving the first-world problem of “knowing where you are” or “having Internet”.
NASA has done a large amount of work to use satellite data to forecast and then work to improve agricultural yields covering the entire planet. It definitely isn’t necessary, but to dismiss the improvement that has been made is crazy, and I’d hardly call “feeding people around the world” a first-world luxury given by space travel.
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> It realistically affects practically nobody alive
Do people in the Global South not use GPS or consume weather forecasts?
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The paper in question is here: https://link.springer.com/article/10.1007/s40295-024-00458-3
It adds to a pretty large body of literature around this subject, the gist of which is "risk is going up, but we don't really have a good way of estimating what that means in terms of actual collision rates".
As long as it is militarily and commercially viable then the number of satellites will continue increasing, regardless of what academics have to say about collision rates. As per usual this is a coordination problem and in case people have not noticed nations are becoming less coordinated and more insular.
> in case people have not noticed nations are becoming less coordinated and more insular.
And what is your yardstick for measuring this? As far as I can tell this is the opposite of true. It's a popular national news meme but I don't believe it's been measured in any reliable way.
I don't know about whether it is more or less common, but there has been international drama over conjunctions over the last several years
https://spacewatch.global/2021/12/spacewatchgl-share-chinese...
I won't comment on the broader point about how insular countries are becoming, but on this specific topic I'd say that the international reaction to global warming, which appears to be a very similar situation, shows exactly how little action is likely to happen.
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We need a Mega-Maid like in Spaceballs to clean up the mess: https://spaceballs.fandom.com/wiki/Mega_Maid
lasers. autonomous fan-beam laser sats to vaporize prograde surfaces of debris to lower altitudes.
There might be a cool storyline where we have to use enormous ground based lasers to clean up and start again.
Could even look a bit like the iconic Gibraltar WW2 search lights photographs.
What would zapping a satellite with a laser achieve? I suppose if you get it hot enough to melt everything, without anything flying off, then it would turn into a spherical drop of molten scrap... but then what?
You ablate part of it on the prograde side to create a small retrograde thrust which will deorbit it.
I think the right move is to merge this approach with goo blobs. We launch a large goo blobs or nets into a few strategic geostationary orbits and now you only have to ablate objects so they hit the goo then deorbit the goo once it is full (or just leave it there) as they would be large known orbits.
I assume the poster means to change its trajectory.
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My understanding was always that LEO is much less of a Kessler risk due to atmospheric friction - ie: in the absence of active control and regular correction, LEO objects will gradually de-orbit themselves. It's the the higher geostationary orbits that pose the problem.
Depends on where in LEO. Explorer I had a perigree of about 350km and lasted for 12 years, though the orbit was highly elliptical. 900km and above is stable for thousands of years and well within the (circular orbit) LEO ceiling of 2000km.
The parallels to global warming appear to be close enough that this could be a good area to study what actually changes behavior on a global scale for a global environmental problem. I suspect this is easier to 'fix' mainly because there are fewer entities involved so not a total parallel, but it still might be informative to see when in the crisis arc action actually starts happening and what messaging impacted that timing.
VLEO/LEO is the safest place to put satellites is it not? They'll eventually deorbit themselves if you do nothing, no?
The worst place for space junk is high orbits it would seem like. Earth was wildly visited by an Apollo rocket stage a few years back! That is pretty wild.
I love Sabine Hossenfelder's videos but the audio effects on the transitions are killing me.
They're a little too similar to my phone's built in sounds I suppose. Nothing I can't get over though. What about them is "killing you"?
Paper: https://link.springer.com/article/10.1007/s40295-024-00458-3
Anyone have an open link?
I would think newer sats will have collision avoidance capabilities and older ones will just crash. Maybe even clean up sats will be developed to collection them
Satellites fail (lost control, or spontaneously explode). Very small debris is everywhere and under 5-10 cm largely untracked, but some are working to fix this gap.
There is no incentive large enough for cleanup (it's expensive, nobody can/wants to pay, and there are a lot of objects)
Leo starts at 7.8 kilometers per second and speed plus secondary and subsequent collisions with very small debris makes it impractical. Also carrying fuel to react frequently would dramatically change the entire mission.
If your non refuelable sat is good for 6 months it probably no longer makes sense to launch it.
With currently deployed tech, most of the smaller orbital debris is not (usefully) track-able.
At orbital velocities, you gotta know it's coming to be able to avoid it.
And a orbital velocities, the untrack-able stuff can still kill a satellite.
Positioning a large, armored satellite in low or mid-Earth orbit significantly enhances its strategic value for both offensive and defensive anti-satellite operations. Such a platform could serve as a pivotal asset in maintaining orbital dominance, offering rapid response capabilities to neutralize threats and protect critical infrastructure.
In other words, welcome various "death stars" to keep order against malicious Kessler style attacks, etc.
"armored"
I don't get the impression that you've looked at the physics of orbits.
Everything up there carries tremendous kinetic energy.
It would be pretty hard to build something strong enough to take on intentional collisions, let alone large debris.
Fun reading: https://www.esa.int/Space_Safety/Space_Debris/Hypervelocity_...
Here's a picture to illustrate: https://www.esa.int/var/esa/storage/images/esa_multimedia/im...
That helps nothing on the civilian side. Blowing up a sat will do nothing but raise long term risk.
Some sort of platform that can launch 'space drones' to deorbit a dead satellite before it crashes or if something else would happened to cause a collision, that could be useful, but, probably expensive.
What do you assume happens to a "neutralized threat" in terms of space junk?
Perhaps it is recycled aboard the large armored satellite or propelled into the Earth's atmosphere so it can burn up.