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Kessler syndrome is a chain reaction where satellites and debris collide with each other, eventually resulting in the obstruction of space and its unusability.

Imagine we had the same situation around a Dyson sphere, with millions of reflective panels or living habitats,

How do we prevent a small local catastrophe between two satellites escalating into a Keseler syndrome disaster?

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    $\begingroup$ This is trivially resolved by diverting a small amount of the energy collected by the satellites for ion thrusters. A Kesler syndrome problem would only exist if those millions of satellites were too close to the sun. From an engineering perspective, you want to be close enough to maximize energy absorption, far enough to minimize damage due to solar radiation/heat, and efficient enough to not have to pack satellites together too closely. It's not worth building the solution if you can't meet those expectations. $\endgroup$
    – JBH
    Mar 3 at 19:53
  • $\begingroup$ Beware solar storms and mass ejections kicking huge numbers out of orbit. $\endgroup$ Mar 4 at 22:05

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There are plenty of standard techniques to fight Kessler syndrome, but a Dyson sphere or Dyson swarm gives us even more options.

The standard options include a mix of short-term and long-term strategies:

  • Active station-keeping to prevent imminent collisions. As suggested by JBH, this might be achievable by ion engines powered by the solar energy -- assuming sufficient advance notice, since ion engines typically don't produce massive thrust.
  • Deorbiting aging parts of the structure, or moving them to assigned graveyard or disposal orbits, where they will either stay away from the rest of the sphere/swarm or else burn up in the Sun.
  • Active debris removal using specialized spacecraft, which would be costly but might give the civilization some added peace of mind.

A Dyson structure does give us two additional weapons in our anti-Kessler-syndrome toolkit. First, the inclination of the orbits can take any value you want; they don't all have to be in the ecliptic plane. This enables you to more easily space them out. You can also opt to place elements of the structure at different semi-major axes -- again, lessening the odds of collisions.

Second, the Sun already engages in active debris removal through the Poynting-Robertson effect, sending particles in the micrometer to millimeter range spiraling into it. The timescale for this effect scales as the square of the particle's semi-major axis (Klačka & Kocifaj 2008). A dust grain orbiting at $\sim$0.01 AU should spiral into the Sun within a year or so, and I would expect similar results from similarly-sized fragments of a destroyed spacecraft. Therefore, placing the structure close to the Sun would ensure the that the smallest bits of debris are naturally removed fairly quickly.

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Keep all satellites orbiting on a single plane

Kessler syndrome is dangerous around planets because in order for a satellite network to be useful we need to orbit them in a lot of different directions to get full coverage. This means that if you have 1 satellite moving at 7.8 km/s in one direction, and it side-swipes another, moving at 7.8 km/s in another direction, then the impact will be highly energetic.

But a Dyson Swarm does not need to orbit satellites at every possible orbital path, because you don't need to use these satellites to map out the sun. Even though your satellites may need to move at 18.6 km/s to maintain a 1 AU orbit, at any give point around the sun, all of the satellites will be moving at more or less the same speed and direction as any other satellite; so, if they do encounter debris from another satellite, it will be at much lower relative velocities so that meteor sized debris will just bounce off of you and larger stuff will be easy to see coming and avoid, or be easy enough to match speed with and salvage.

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