There are a lot more large pieces of space junk in LEO than that. We track about an order of magnitude more than that above 5cm diameter. Exploded upper stages, debris from collisions, discarded separation bits and pieces, no-longer-active satellites.
4000 is still a large number, especially at a higher LEO altitude where junk lasts forever. There's a reasonable case to be made for shifting to a regime where we require that satellite providers remove more mass and more pieces of debris from orbit than they put into orbit. But we don't want to split the baby and force them into bankruptcy either. The weak interim guidance might be that built-in deorbiting devices are required for anything with more than a ~10 year orbital lifetime. This doesn't end the Kessler Syndrome cascade, but it at least doesn't contribute very much. Presently there is only a ~25 year voluntary initiative, and adherence is not universal.
The most advanced initiative in this area is the geosynchronous graveyard belt, which the FCC enshrined into law for US telecom providers, but even that fails a large fraction of the time.
4000 is still a large number, especially at a higher LEO altitude where junk lasts forever. There's a reasonable case to be made for shifting to a regime where we require that satellite providers remove more mass and more pieces of debris from orbit than they put into orbit. But we don't want to split the baby and force them into bankruptcy either. The weak interim guidance might be that built-in deorbiting devices are required for anything with more than a ~10 year orbital lifetime. This doesn't end the Kessler Syndrome cascade, but it at least doesn't contribute very much. Presently there is only a ~25 year voluntary initiative, and adherence is not universal.
The most advanced initiative in this area is the geosynchronous graveyard belt, which the FCC enshrined into law for US telecom providers, but even that fails a large fraction of the time.