Was not aware they scuttled 1,200km ka/ku band constellation and corrected in another reply. Either way, per your citation, the current plan still puts 10k+ objects in 400km+ orbits where debris hangs around for much longer. Primary point still stands - starlink isn't limited to sub 400km constellation and kessler syndrome risk for higher orbits is real (risk increase not linear). Especially, if starlink plan to go to 42k above currently planned 30k, most are going to be 400km+ since sub 400km orbits are taken. Unless UN/ITU increase slots, the amount of sub 400km slots are fixed, and expanding megaconstellations including future starlink expansion is going to be satuating orbits with multi year / multi decade decay.
> SpaceX operates its satellites at an altitude below 600 km because of the reduced natural orbit decay time relative to those above 600 km. Starlink operates in \"self-cleaning\" orbits, meaning that non-maneuverable satellites and debris will lose altitude and deorbit due to atmospheric drag within 5 to 6 years, and often sooner, see Fig. 1. This greatly reduces the risk of persistent orbital debris, and vastly exceeds the FCC and international standard of 25 years (which we believe is outdated and should be reduced). Natural deorbit from altitudes higher than 600 km poses significantly higher orbital debris risk for many years at all lower orbital altitudes as the satellite or debris deorbits. Several other commercial satellite constellations are designed to operate above 1,000 km, where it requires hundreds of years for spacecraft to naturally deorbit if they fail prior to deorbit or are not deorbited by active debris removal, as in Fig. 1. SpaceX invested considerable effort and expense in developing satellites that would fly at these lower altitudes, including investment in sophisticated attitude and propulsion systems. SpaceX is hopeful active debris removal technology will be developed in the near term, but this technology does not currently exist.
