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It is research for a book I am writing. The year is 2200. Assume the volume of items in orbit has increased dramatically from today’s numbers. We go to war and blowup all the satellites. Four hundred years later, what would the night sky look like?

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    $\begingroup$ The US Federal Communications Commission recently passed a rule that requires a satellite orbiting at less than 2000 km altitude to reenter the atmosphere within five years after the end of the satellite's useful life. For orbits at high but still LEO altitude orbits (600 km up to 2000 km), achieving this will require a reentry engine firing, so this rule may not be useful for satellites that are intentionally destroyed. $\endgroup$ Commented Apr 26, 2023 at 20:59

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Objects in low orbits tend to be slowed by atmospheric friction and other interactions, falling down relatively quickly. The deorbiting timescale for satellites under 800 km altitude is 100-150 years, so they will all be gone. Stuff above that altitude will remain, although lighter dust and grains will tend to disappear too (they get subjected to light pressure and electric charging). So if there are rings, they will start at a few hundred kilometers and extend outwards.

There might be stability problems if the mass up there is big enough, but in this case this is unlikely unless there is a lot of big objects.

The big problem for rings is the Moon, which exerts tidal forces that likely would make them far more diffuse than the neat Saturn-like ones in these renderings.

Together, this suggests that the rings are unlikely to be grand like Saturn's. Even if there was a lot of highly reflective objects up there, as they grind down to fine dust light pressure and lunar tides makes them drift away. The bigger objects remain, but probably as a more diffuse cloud and (since the surface to volume is smaller) less shiny than the dust.

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  • $\begingroup$ It sounds like I am on the right track. I wasn't so much as thinking rings, but rather that you'd see the debris. Two more questions though: In 400 years, would the items that remain have time to form rings, or any structure at all? And from the ground would it be colorful, or likely just white like the moon? My thought was, since satellites tend to be covered in thermal shielding of some sort, the pieces would act something like a broken CD and glint color. Thanks for your help! $\endgroup$
    – Ken
    Commented Apr 27, 2023 at 14:13
  • $\begingroup$ @Ken - I think 400 years is enough for hazy rings (it is after all many thousands of orbit periods of the components, and most start in the equatorial plane). I suspect the colour would be boring, since even individually colourful pieces would be too small to see and blend together into a haze. A few big pieces might cause glints, but after centuries most surfaces will be pretty dull due to erosion. $\endgroup$ Commented Apr 27, 2023 at 22:34

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