>but a question whether it's a relevant concern in the context of Starlink
I kind of thought it was pretty obvious that my statement was specifically in the context of Starlink, given that I explicitly acknowledged that higher up megaconstellations are a much bigger concern. But it's not at all to a significant degree for Starlink due to orbital decay by atmospheric drag. Have to get above 550-600km or so for unpowered lifetimes to really start to stretch out. You might find this Gabbard diagram animation very interesting as a visualization:
It shows all the altitudes against period of all tracked space debris since 1959. Watch what happens around the 550-600km mark in terms of decay acceleration. Starlink, particularly the VLEO ones that are planned to form the majority of the constellation when completed, is essentially passive failsafe. Planned deorbit is still much better than a 1-5 year lifetime of course, but neither will it ever just block us off or render an orbit unusable because they're just plain too low. Anything below those marks (like ISS) requires regular active reboosts to maintain their orbits. When ISS wants to get rid of trash, they can literally just let it go in a big brick.
Kessler absolutely is worth worrying about very much at altitude. But a lot of the coverage and stuff getting shared around about it are 100% backwards. They focus purely on raw numbers of sats. But the absolute best way to avoid Kessler is to go low for as many things as possible, which by definition requires more, cheaper sats that get replaced much more regularly. Massive VLEO constellations are a good thing for space debris not a bad one, because they require both active boosting and even aerodynamics to stay up, and even a worst case direct collision of two sats at ~300km say would result in complete elimination of all debris within at most a month. Starship will make lower altitudes and more safety systems economically feasible.
I kind of thought it was pretty obvious that my statement was specifically in the context of Starlink, given that I explicitly acknowledged that higher up megaconstellations are a much bigger concern. But it's not at all to a significant degree for Starlink due to orbital decay by atmospheric drag. Have to get above 550-600km or so for unpowered lifetimes to really start to stretch out. You might find this Gabbard diagram animation very interesting as a visualization:
https://old.reddit.com/r/space/comments/ld4vlq/gabbard_diagr...
It shows all the altitudes against period of all tracked space debris since 1959. Watch what happens around the 550-600km mark in terms of decay acceleration. Starlink, particularly the VLEO ones that are planned to form the majority of the constellation when completed, is essentially passive failsafe. Planned deorbit is still much better than a 1-5 year lifetime of course, but neither will it ever just block us off or render an orbit unusable because they're just plain too low. Anything below those marks (like ISS) requires regular active reboosts to maintain their orbits. When ISS wants to get rid of trash, they can literally just let it go in a big brick.
Kessler absolutely is worth worrying about very much at altitude. But a lot of the coverage and stuff getting shared around about it are 100% backwards. They focus purely on raw numbers of sats. But the absolute best way to avoid Kessler is to go low for as many things as possible, which by definition requires more, cheaper sats that get replaced much more regularly. Massive VLEO constellations are a good thing for space debris not a bad one, because they require both active boosting and even aerodynamics to stay up, and even a worst case direct collision of two sats at ~300km say would result in complete elimination of all debris within at most a month. Starship will make lower altitudes and more safety systems economically feasible.