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Comment by jordanb | Hacker News Reader

I think the next big war will involve a kessler syndrome, not because people start firing off anti-satellite weapons (since there's a strong component of MAD in doing that) but because the belligerents will have their own multi-thousand satellite constellations in orbit and they will quit coordinating with one another on collision avoidance.

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Starlink is redeploying to 300 miles. Many consider Kessler to be impossible at 300 miles. Any unpowered satellite at a 300 mile orbit will deorbit within a couple of months. But a collision means fragments which deorbit faster because they have a higher surface/weight ratio, and because orbit disturbances lower that time considerably. Any single disturbance that raises aphelion lowers perihelion.

Would collisions cause debris to be ejected into a higher orbit? Although I guess as long as the debris does not pick up any significant speed boost, its orbit would be elliptical and would just collide with Earth (burn up on re-entry)?

Wouldn't a explosion give it that energy?

I'm not sure every satellite would be exploding in the traditional sense with hot gases expanding.

There would be disentigration when satellite pieces rip through other satellites.

How many satellites carry compressed gas for orbit adjustments?

Maybe there is some compressed gas pushing against liquid fuel and oxidizers, but I don't think the fuel and oxidizers would explode. Shooting tanks of gasoline with regular bullets do not cause explosions like movies would have you believe. Well, maybe pure oxidizers might, would there be enough heat generated by the tank being punctured?

the 2009 collision was well documented and there are interesting reports online

e.g. https://ntrs.nasa.gov/api/citations/20100002023/downloads/20...

which has a chart of apogee/perigee of debris. There seem to be examples of debris with _perigee_ above the collision altitude but the vast majority stayed beyond.

300km?

These LEO satellites are low enough that I imagine a Kessler situation would self-resolve within a few years.

A smaller player like North Korea and Iran would not have as much to lose. Iran is doing something similar today, suicide bombing everything it can.

Iran also has a space program with Satellites: https://en.wikipedia.org/wiki/Iranian_Space_Agency

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