@Brad_Rosenheim

Except ... when this claim (not about the satellites re-entering, just the amount of damage they cause to the atmosphere) started circulating some months back, I read an article (somewhere...) that analyzed the amount and type of matter it would distribute, and it pales in comparison to the amount the earth receives in "space dust" and micrometeroids every day.

Best figure I know of for the mass of "normal" space matter hitting our planet is 5,200 tonnes / year:
https://www.scientificamerican.com/article/antarctic-study-shows-how-much-space-dust-hits-earth-every-year/

The current Starlink satellites are "gen2 mini", and are 740 kg. So you would need to de-orbit more than 7,000 of them every year - not 4 per day - to even match the natural space dust falling on earth. Except it's even worse (for the argument) than that, because 740kg is their launch mass, including all their maneuvering fuel/gasses, which by definition are gone before the satellites are deorbited. I don't have an exact figure for how much mass the fuel accounts for, but it wouldn't surprise me if it was more than 25% of the mass of the spacecraft at launch.

The residue left in the atmosphere doesn't seem to be a very big deal.

#science #mass #satellite #deorbit #RunTheNumbers #calculation

edit: typo

@shnonks Starlink satellites orbit at 550 km. Natural decay time at that altitude is 54 years (https://www.reddit.com/r/SpaceXLounge/comments/ekyibk/orbital_decay_times_and_the_starlink_bus_why_500/). Not sure how small particles post collision would affect the decay time, but we are not talking 5 years unless they actively deorbit and they can't actively deorbit if they are destroyed.