Thread by @planet4589

I've just written about the Starlink reentries in JSR latest.html, but I'll repeat my comments here. After 63 years of orbital spaceflight this is a qualtiatively new kind of orbital decay (hi @orbital_decay !)
(1/n)

@orbital_decay it's not a normal deorbit and not a
normal orbital decay, but something inbetween. The Starlink satellites are, apparently, retired by continuously lowering their orbit with electric propulsion.

@orbital_decay Reentry occurs in a way similar to uncontrolled reentry - eventually the satellite is low enough and the ambient density is high enough that the vehicle heats, breaks up and is destroyed.

@orbital_decay The crucial point here is that the *location* of the breakup on the Earth is unpredictable and uncontrolled, in contrast to an impulsive deorbit where the rapid elliptical-orbit descent from a relatively high apogee
means that reentry location is predetermined fairly precisely.

@orbital_decay These Starlink retirements should perhaps be termed not deorbits but
`propulsion-assisted orbital decay' - they are more like normal
uncontrolled orbital decay but speeded up by the thrusters.

@orbital_decay Caveat: this is just what I'm inferring from looking at the TLEs and the decay notices. I may be missing some final controlled death plunge but looking at the available data I don't think so.