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There are tentative signs that this is happening right now. As in: each collision causes debris that on average causes more than one additional collision, causi

There are tentative signs that this is happening right now. As in: each collision causes debris that on average causes more than one additional collision, causing collision rates to go up exponentially. But so far it's not anything like in Hollywood movies, it's just a graph slowly going up. There are about 12000 satellites orbiting earth. That looks like a lot on a map, but 12000 objects spread over an area larger than the surface of the earth isn't all that much Like all exponential processes it will become a major issue if we don't address it, but this is one that starts pretty slow and is well monitored

spiritplumber 9mo ago
Yep. That's the things about exponential curves, it's a graph slowly going up until it's no longer "slowly". https://www.thefrogdoctrine.com/p/the-29th-day https://www.thefrogdoctrine.com/p/the-29th-day
- indoordin0saur 9mo ago
  This can't go up forever. There is only so much mass up there in orbit, and much of it is in low earth orbit so will fall back into the atmosphere quickly as it's trajectory gets knocked off course.
childintime 9mo ago
> 12000 objects spread over an area larger than the surface of the earth isn't all that much People keep saying this, but the only way to assure there is no collision is to have non-intersecting orbits, but that is not going to work: not enough space. It's a tell that SpaceX is now lowering the orbits, even though their satellites mostly move in flocks that maintain a formation relative to each other: because the other ways are exhausted. Of course if they do cause a (low orbit) Kessler syndrom, then they don't have a business any more, and SpaceX will have achieved the opposite of its stated goals. The major reason to lower these orbits is likely the risk of a terrorist state turning these constellations into a weapon, by willingly causing the Kessler syndrome. SpaceX isn't going to tell you that, just as it doesn't tell you it's the USA's most important military asset.
- notahacker 9mo ago
  > The major reason to lower these orbits is likely the risk of a terrorist state turning these constellations into a weapon, by willingly causing the Kessler syndrome. Hard to see how the repositioning appreciably alters this risk, since there are still thousands of satellites in the original plane to get hit by shrapnel from intentionally caused collisions, and the satellites in the lower orbit aren't invulnerable to it either Suspect there's a rather more practical calculation that the extra thruster firings needed to main position in a lower orbit with more atmospheric drag are offset by the smaller number of conjunction avoidance manoeuvres they need to undertake in less congested space (the cost of lowering the orbit is simply deducted from their original delta-v budget for end of life deorbiting). In simple terms they get lower accidental collision risk without operations in the lower orbit shortening satellite lifetime.
  - ben_w 9mo ago
    > Hard to see how the repositioning appreciably alters this risk, since there are still thousands of satellites in the same plane to get hit by shrapnel from intentionally caused collisions, and the satellites in the lower orbit aren't invulnerable to it either Yes, but the lower the orbit, the faster atmospheric drag (which isn't zero, just low) cleans up a cascade.
    - childintime 9mo ago
      Exactly. And this is likely to be the only valid reason for the orbit change.
    - notahacker 9mo ago
      Feel like I'm repeating myself here, but they're moving less than half of them, which is going to have a negligible impact on a state with sufficient ASAT weapons' ability to create a massive mess with the many thousands of Starlink satellites operating in their original plane. Not even like the satellites in the lowest orbit are insulated from the effects of debris cascades set off in higher reaches of LEO either Plenty of operational reasons to want a large fraction of your constellation in a slightly lower orbit, none of them involve "terrorist states"

spiritplumber 9mo ago

Yep. That's the things about exponential curves, it's a graph slowly going up until it's no longer "slowly". https://www.thefrogdoctrine.com/p/the-29th-day https://www.thefrogdoctrine.com/p/the-29th-day

indoordin0saur 9mo ago
This can't go up forever. There is only so much mass up there in orbit, and much of it is in low earth orbit so will fall back into the atmosphere quickly as it's trajectory gets knocked off course.

childintime 9mo ago

> 12000 objects spread over an area larger than the surface of the earth isn't all that much People keep saying this, but the only way to assure there is no collision is to have non-intersecting orbits, but that is not going to work: not enough space. It's a tell that SpaceX is now lowering the orbits, even though their satellites mostly move in flocks that maintain a formation relative to each other: because the other ways are exhausted. Of course if they do cause a (low orbit) Kessler syndrom, then they don't have a business any more, and SpaceX will have achieved the opposite of its stated goals. The major reason to lower these orbits is likely the risk of a terrorist state turning these constellations into a weapon, by willingly causing the Kessler syndrome. SpaceX isn't going to tell you that, just as it doesn't tell you it's the USA's most important military asset.

notahacker 9mo ago
> The major reason to lower these orbits is likely the risk of a terrorist state turning these constellations into a weapon, by willingly causing the Kessler syndrome. Hard to see how the repositioning appreciably alters this risk, since there are still thousands of satellites in the original plane to get hit by shrapnel from intentionally caused collisions, and the satellites in the lower orbit aren't invulnerable to it either Suspect there's a rather more practical calculation that the extra thruster firings needed to main position in a lower orbit with more atmospheric drag are offset by the smaller number of conjunction avoidance manoeuvres they need to undertake in less congested space (the cost of lowering the orbit is simply deducted from their original delta-v budget for end of life deorbiting). In simple terms they get lower accidental collision risk without operations in the lower orbit shortening satellite lifetime.
- ben_w 9mo ago
  > Hard to see how the repositioning appreciably alters this risk, since there are still thousands of satellites in the same plane to get hit by shrapnel from intentionally caused collisions, and the satellites in the lower orbit aren't invulnerable to it either Yes, but the lower the orbit, the faster atmospheric drag (which isn't zero, just low) cleans up a cascade.
  - childintime 9mo ago
    Exactly. And this is likely to be the only valid reason for the orbit change.
  - notahacker 9mo ago
    Feel like I'm repeating myself here, but they're moving less than half of them, which is going to have a negligible impact on a state with sufficient ASAT weapons' ability to create a massive mess with the many thousands of Starlink satellites operating in their original plane. Not even like the satellites in the lowest orbit are insulated from the effects of debris cascades set off in higher reaches of LEO either Plenty of operational reasons to want a large fraction of your constellation in a slightly lower orbit, none of them involve "terrorist states"