alt Hacker NewsStarlink 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)?