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Comment by farseer | Hacker News Reader

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?

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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

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).

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