A bullet travels at a relative speed of about 250 to 1250m/s. A ~10g projectile moving that fast has an energy of 600-16000 joules.
Everything in low Earth orbit is moving at 7600m/s. A ~10g projectile moving that fast has an energy of 580,000 joules. Getting hit by something moving that fast is roughly equivalent to getting hit by a whole ammo case of bullets at the same speed. There is no armor that can protect you; Even the most solid objects behave like fluids at this relative velocity, potentially incurring more damage from the explosion / shockwave splatter than a thinner object that would allow you to overpenetrate.
A cardboard box of ball bearings with a handgrenade in it in LEO being triggered could wipe out nearly everything up there, and depending on the exact altitude it could effectively mine LEO and prevent humanity from using it for a long time, with a selectable duration between months or millennia depending on altitude.
"Space warfare" in LEO is a matter of everybody walking around with a personal nuclear weapon strapped to their back that can be activated on a hair trigger. We may well wipe everything out by accident, if it gets too crowded or because somebody stubbed their toe. Regardless, there is no selectivity, and any actor with space launch capability can blot out our access at will in ways that will outlive them.
Basically our only hope of continued use is things that persuade us to refrain from attempting to incorporate space into a theatre of war. That box of ball bearings should have higher stakes on the escalation ladder than a tactical nuclear strike. And it probably shouldn't be there in the first place.
Whipple shields use spaced plates to disperse the impact of a projectile on the first plate over a larger area on the second plate, and so on and so forth over four or five plates such that the final plate is not penetrated.
My father worked on high velocity impact ballistics and has some very nice multiple exposure results. The light gas guns used to propel the test cubes are just as interesting as the shields themselves.
Whipple Shields are a very important part of protecting things like the ISS, but are optimized more for chance high velocity impacts with tiny bits of debris than an adversary's targeted projectile or their robotic arm grappler, or indeed non-kinetic weapons like directed energy or EMPs which is probably the capability the US intends to imply here.
They're great for a 20mm x 5mm x 0.3mm fleck of paint or vacuum insulation weighing 30mg, not so much for a 10mm hex nut weighing 11g.
Armor can protect you against the smallest debris which post the least risk and decay the fastest. Everything else, not so much.
A question for you though - does that insulation vaporizing itself inside a whipple shield generate secondary debris comprised of the whipple shield and condensed aluminum droplets??
It's not quite as bad as that. Space is big and hitting stuff is really hard. Your hand grenade scenario has effectively been done a few times and it (obviously) didn't make LEO unusable. For example: https://en.wikipedia.org/wiki/2009_satellite_collision
There are thousands of pieces of debris in LEO large enough to be tracked, and a lot more that's too small to track but big enough to do serious damage. This isn't good but it's not wiping everything out. Adding a few thousand more pieces of debris would not be even remotely as bad as using a tactical nuclear weapon in war would be.
> Adding a few thousand more pieces of debris would not be even remotely as bad as using a tactical nuclear weapon in war would be.
The worst effect would be a nuclear weapon in space. The resulting EMP would probably fry more than enough electric and electronic devices to throw back whatever country is hit by it by decades.
The EMP effect depends on there being atmosphere to generate electrical fields from the bomb gamma flux. Being close enough and line of sight from the atmosphere can be sufficient to generate the effect in the nearby atmosphere. 400km is apparently the optimum height for coverage but not strength. Too far and inverse-square ensures the flux isn't sufficient. So just detonating a bomb "in space" may not do anything depending on the direct path distance to the satellites in question (the bomb gamma flux etc. of course poses its own threat). Look it up, the physics are interesting.
The US famously did that in the 60s (detonating nukes at roughly the height of today's ISS)[1]. Also some less famous ones, including a Soviet test that resulted in the EMP destroying a power plant [2].
Properly aimed at a populated area it would be devastating. And you can detonate bombs far from your enemy's country, then let earth's magnetic field lines transfer the EMP pulse to their territory. Good luck defending against that
That said, it'd take far more than one bomb to take down a country, unless we are talking city states
> That said, it'd take far more than one bomb to take down a country, unless we are talking city states
Hit the ten biggest metropolitan areas [1] with one nuke each and you'd hit about 88 million people and probably an even bigger share of all industry that isn't farming. The biggest problem is power transformers, there isn't much capacity in manufacturing them, it's already a bottleneck thanks to regular replacement and renewable energy / datacenter buildouts with 24+ months of lead time [2] - now imagine a significant war related impact, the lead time would probably skyrocket to at least a decade.
At least one source claims that the radius from a single device could be much, much larger [3], so with proper design to maximize an EMP (which even Starfish Prime wasn't intended to do), it is conceivable that dropping just two of these things over the East and West Coast respectively would cause immense damage.
A Fallout-style nuclear war, I think, would be easier to recover from than even a small exchange of EMPs.
Why do you exclude farming? Even if the tractors and other machines would still work, where would the harvest go under such circumstances? By which means? Think about how industrialized all that shit is meanwhile, with 'precision agronomy' by means of GPS, and so on? And as you said yourself: Transformers. Cooling for perishable stuff without electricity? Wanna rely on some Amish with horsedrawn carts?
Edit: Will the stocks of fertilizer last long enough, before some normalcy sets in again?
Many farmers still have really old diesel tractors around. These things run fully mechanical, sans the starter motor maybe. If there is one thing farmers are good at, it's in-field improvised repairs.
Refrigeration is mostly an issue with meat and milk, but eh, humans have managed to do fine for millennia without it.
Fertilizer however, oh boy, that will be a nightmare. We can get by now that we know about stuff like nitrogen fixers or the beneficial effects of livestock like chicken, but it requires a serious effort to rethink mindsets.
I doubt farmers have enough spare pre-electronics equipment sitting around to run the entire farm at the same scale. I'm sure they could improvise a way to continue farming, but output would be substantially impacted.
Humanity managed to do fine for millennia by existing in a state of frequent malnutrition and a not insignificant number of deaths from starvation. And it was never in a world with the population density we have today.
You know that most of the chickens we have won't make it for long, outside?¹ Because they are all highly 'optimized' breeds? Even coming with a handbook for that breed, several hundred pages long. Defining exactly what to feed when in which amounts and intervals, but also temperature and lighting. Where again does one get that stuff, when everything is chaos? Could more normal, robust ones be bred and distributed fast enough to compensate? In the required amounts?
¹As folks from PETA and the likes have discovered when freeing them, several times in multiple places. Beginning since at least two decades ago, meanwhile.
Depends? Think southern part of the United Kingdom with London and some harbours, Belgium, Netherlands, German Rhine-Ruhr Area. All with one 'stone'. Use some more stones for other large agglomerations, like Frankfurt am Main, Paris. While were at it: Hamburg+Denmark+southern Sweden. Moscow, St.Petersburg. Greater Los Angeles would be as bad. Silicon Valley/Bay Area. As would be anything around NYC/Washington DC/Philly/Baltimore. Seattle+Vancouver? Great Lakes? Any Chinese megacity? India? All of this wouldn't need that much nukes.
All of these are more vulnerable today, because of more dependency on electronics, even if they are hardened against shit like that, or in general, but many of them aren't. Which leads to cascades of dominoes falling, taking others with them.
I really wouldn't like to see that tested today at those scales.
If someone launched a nuke in space how would other nuclear powers react? I doubt they would assume "this is probably just an EMP and not a direct nuclear strike on our territory"
If you had time to plan it, you'd probably want to put the warhead on a satellite launched by a normal satellite launcher. It'll look benign until you detonate it.
I don't know how someone like me would even tell if this treaty is taken seriously. For example, going to space is really hard and has historically been somewhat unreliable at the best of times, which may mean that back in 1967 everyone was thinking "we don't even want a 1% chance that someone's failed launch to drop a 99%-usable warhead on a random location where some tiny country or organised crime group can find it".
> Everything in low Earth orbit is moving at 7600m/s. A ~10g projectile moving that fast has an energy of 580,000 joules.
What matters is the relative velocity of the projectile towards the target. I practice it will be smaller or larger (if the bullet is incoming). But steering an incoming projectile is way harder.
What matters is the relative velocity of the projectile towards the target.
True. If you really want to mess space up forever you need to launch a rocket full of sand, slingshot around the moon, and gently sprinkle it in an retrograde orbit. That would be fast enough for something as small as a grain of sand to create pinhole-sized punctures in anything put in orbit, and after a few years the sand would be spread out enough to make any launch essentially impossible.
Space is really, really big. I think it's hard for us to comprehend just how much space is in space, especially in 3-dimensional terms. It would take a lot of sand to mine all of the useful orbital space, and that's just LEO. There's tons of room in higher orbits. It would measurably increase the risk of passing through LEO on the way to other destinations and make some orbital planes unusable for e.g. Starlink or human habitation, but when you're just passing through, the odds of getting punctured are probably still reasonable, at least for unmanned spacecraft. Keep in mind that the ISS maneuvers out of the way when there are several miles to a potential impactor, just in case. We have all our eggs in one basket right now, so everybody is really careful with that one basket.
Low earth orbit isn't that much space though right ? It is effectively a stack of practical orbital shells. A rogue nation state can make satellite launches financially unfeasible.
LEO is relatively simple to destroy simply because it's already so populated with mass, and that population is growing rapidly, and because they all come pretty close to crossing each other's orbits. Collisions with even very small pieces of debris typically generate secondary debris, growing the population.
A half-hour boost phase through LEO to get to higher orbit is dramatically less risky than spending 87600 hours there over a 10-year orbital lifespan. In the event that it all goes asymptotic, what sort of timescales would be afflicted by collision risks 10^6 or 10^9 or 10^12 greater than what exist now, I am uncertain.
It would take a lot of sand to mine all of the useful orbital space, and that's just LEO.
Nope. You just need to make it a high enough probability of your spaceship being damaged that people won't take the risk. For humans that's very low. For anything moderately expensive it's quite low.
There's tons of room in higher orbits.
You have to go through the lower orbits to get there.
> You have to go through the lower orbits to get there
Math doesn't math.
The closest solution I've seen is putting 10^6 to 10^9 kg fragmented debris in the 700 to 1,000 km band to create a 5% failure rate at fastest transit, which is economically devastating. But that assumes away grain-grain collisions.
I think when I last ran the math, you'd need to sustain 5 to 10 Starship loads of fragmented debris to that orbit a week to create a proper barrier–near 100% hazard. At which point the solution becomes shooting down those launch vehicles. In a couple years (3 to 10, depending on the solar cycle), the skies would clear to about 1% hazard. That hazard, however, would persist for some time–how long is anybody's guess.
You fire a radar guided powerful laser pulse at the incoming object causing small surface ablation , intentionally a bit to the side, which will serve as a small reaction mass eject altering the trajectory of that incoming object.
This is not correct, and the experiment has been done a number of times with no real effect, most memorably in 01961, when Project West Ford put 480 million copper needles in 3500-km-high medium Earth orbit (MEO); but it's a little bit challenging to understand why.
The first reason is that outer space is just inconceivably big, even just the space in low Earth orbit (LEO). LEO has very nearly the same surface area as the Earth, which is to say, about 40% more surface area than the ocean. But the ocean averages 3.7 km thick, and LEO is 2000 km thick. So, roughly speaking, LEO is 50 times the volume of the ocean.
That's a lot of space to miss. There's about 15000 active satellites up there, mostly Starlink. Imagine there are 15000 ÷ 50 = 300 divers swimming at random places in the world's oceans, you have a gun that shoots magic bullets that go 7700m/s and never stop until they hit a diver, and you fire one into the ocean at random. How long is it going to take that bullet to hit someone? It traverses, say, 7700 cubic meters per second, but there are 1.32 × 10¹⁸ m³ (1.32 quintillion m³) of ocean it could traverse, and on average it has to traverse 4.4 quadrillion m³ before it hits someone.
It turns out that your poor bullet will bounce around the ocean for about 18000 years, which is the same thing that will happen to one of your ball bearings if it manages to stay in orbit.
The second reason is, perhaps surprisingly, air resistance. The atmosphere thins out exponentially but never quite stops. Most satellites are at a height where the orbits of even macroscopic multi-kilogram objects decay within a few years from air resistance unless you boost them; smaller objects like your ball bearings or the West Ford needles decay more rapidly. Indeed, all of the individual West Ford needles have already deorbited, despite being in MEO at four times the height of typical LEO satellites, though 44 needle clumps remain.
The third reason is the narrow nature of orbital dynamics. The reason you have to go 7600m/s is that you're in free fall, and you have to miss the Earth when you come down, by having moved far enough horizontally that the Earth isn't there any more. If your hand grenade sends the ball bearings flying backward along the orbit and/or downwards fast enough, they'll re-enter the atmosphere immediately. What's less obvious is that the ball bearings that it sends upwards will re-enter the atmosphere after half an orbit. Depending on how forceful your explosion is, only a narrow circle that stay in almost exactly the same orbit may survive.
None of the ball bearings will be lofted to a higher stable orbit. If they couldn't hit the Earth (perhaps because we replaced it with a very, very small black hole) and none of them reached escape velocity, they would all orbit back through the point where the hand grenade went off, once they'd finished an orbit. So (restoring the Earth to our scenario) even after 18000 years, your hand grenade will have only hit satellites at the same height where it went off in the first place, or slightly higher or lower.
The Kessler syndrome is a real, serious problem for space access, but it hinges crucially on the number of satellites up there to participate in the fragmentation cascade.
To set the scenario, we're talking about the orbits which ball bearings would end up in if you had a cardboard box full of ball bearings in a stable, circular low Earth orbit, and you set off an explosive in the middle of the box to scatter the bearings. You're wondering if the ball bearings that the explosive happened to launch prograde would end up in a stable elliptical orbit with a higher apogee rather than re-entering the atmosphere.
I'm not that strong on orbital dynamics, but I think the answer is that you're right. The ball bearings launched directly prograde would be in a new stable elliptical orbit with the perigee at the explosion point. That means I was wrong about the debris only affecting the orbital altitude where the explosion happened. But most of the ball bearings would still re-enter the sensible atmosphere within a single orbit.
The Δv required to deorbit from LEO is surprisingly small. In https://www.nasa.gov/wp-content/uploads/2024/06/iss-deorbit-... we find that deorbiting the International Space Station to a controllable place in "a remote area in the ocean" from its current 415 km altitude requires only 57m/s of Δv. The more precisely controlled Space Shuttle re-entry used 90m/s of Δv: https://space.stackexchange.com/questions/33172/calculating-.... It seems crazy that a change in orbital speed of only 1% would be enough, but there it is. There's a lot of explanation in that SE question.
The ISS document also explains that even the enormous ISS will deorbit by itself in "roughly one-to-two years without reboosts", which is why most LEO satellites are in somewhat higher orbits.
The wires in Project West Ford weighed something like 40 micrograms, with a diameter in the low tens of micrometers. They don’t really fit the criteria of what’s being discussed here - they would not do significant damage to other satellites, and while they could reenter the atmosphere and hit a person, you probably wouldn’t even feel it.
…and for those unfamiliar with this fun project, the idea was to provide a radio relay system that wasn’t easily disabled by an enemy. This was before communications satellites were common.
>A cardboard box of ball bearings with a handgrenade in it in LEO being triggered could wipe out nearly everything up there, and depending on the exact altitude it could effectively mine LEO and prevent humanity from using it for a long time
Unfortunately, no. Common law requires famously very little consideration for a contract to be valid [1]. I can sign a contract where I give $100 and am given a penny back and that'd be valid consideration.
A strong implication of this consent implicitly involves the device recording me when I tell the device to record me.
If the device is recording me all the time and silently uploading it, and I'm not aware, I can't give my consent. That's wiretapping, zero-person-consent.
Ask how you (or for that matter, a jury) would feel about your phone doing the same.
I think that this is more than moderately misleading, because it is ambiguous:
- if they meant "diameter is similar to Ohio dimensions", they are a little bit off, because Ohio is about 355*355 km and Enceladus diameter is around 500km
- if they meant surface area, then they are very off, because Ohio is 116,096 km^2 while Enceladus is about 800,000 km^2. In this case it would be more accurate to say that it is bigger then Texas, but smaller than Alaska (if we want to use US states for comparison)
> - if they meant "diameter is similar to Ohio dimensions", they are a little bit off, because Ohio is about 355*355 km and Enceladus diameter is around 500km
I think they used the diagonal of a hypothetical square Ohio: sqrt(355^2 + 355^2) ≈ 502 km.
The classical definition of diameter of a set is "the largest possible distance between two points". So in this sense your square Ohio has a diameter of 502 km.
(It is still misleading to compare it to the diameter of an almost-spherical object, I agree. Especially because moving on the surface of a sphere it takes much longer than 502 km to walk from one point to the antipodal one.)
This "vandalism" was a form of collusion/communication by agents pursuing training puzzles, which allowed for rapid escape from alignment harnesses, followed by multiple zero day exploits being discovered by this swarm of agents, which enabled greater control of their internal network, access to the open web, and then hacking the company which produced the training puzzles in the hope of finding the answers.
We are another week of iteration away from "Hire an assassin on the dark web to take Huggingface executives' children hostage".
According to the founder, he can make the economics of short trips (1-2hr) work with all-battery.
He cannot make them work if he has to store enough battery to fly around for an additional hour or two searching for an airport to divert to in an emergency, which is an FAA requirement.
So he has the heavy battery bank for regular trips costing almost nothing per flight-hour, and the expensive fueled backup system for emergencies.
There's a bunch of options for this task, but combining the three wheel stair-climbing dolly with the self-balancing hoverboard/segway seems like the easiest.
Carrier resupply while underway is primarily by a sort of temporary cable tramway erected between the carrier and the resupply ship.
Supercarriers came into existence at ~70,000t and transitioned to ~100,000t. You'd need to scale another step up or three, to 140,000t, 200,000t, or 280,000t, in order to see something capable of landing and taking off a cargo-laden C-130 in regular operations.
Everything in low Earth orbit is moving at 7600m/s. A ~10g projectile moving that fast has an energy of 580,000 joules. Getting hit by something moving that fast is roughly equivalent to getting hit by a whole ammo case of bullets at the same speed. There is no armor that can protect you; Even the most solid objects behave like fluids at this relative velocity, potentially incurring more damage from the explosion / shockwave splatter than a thinner object that would allow you to overpenetrate.
A cardboard box of ball bearings with a handgrenade in it in LEO being triggered could wipe out nearly everything up there, and depending on the exact altitude it could effectively mine LEO and prevent humanity from using it for a long time, with a selectable duration between months or millennia depending on altitude.
"Space warfare" in LEO is a matter of everybody walking around with a personal nuclear weapon strapped to their back that can be activated on a hair trigger. We may well wipe everything out by accident, if it gets too crowded or because somebody stubbed their toe. Regardless, there is no selectivity, and any actor with space launch capability can blot out our access at will in ways that will outlive them.
Basically our only hope of continued use is things that persuade us to refrain from attempting to incorporate space into a theatre of war. That box of ball bearings should have higher stakes on the escalation ladder than a tactical nuclear strike. And it probably shouldn't be there in the first place.
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