[xenadu02]

Modern end-of-life satellite designs are made to cause "rapid disassembly" very high up in the atmosphere to trigger high friction on as many individual components as possible - down to fasteners. This promotes completely re-entry burn up of everything so what reaches the surface is dust that settles back down to the surface (or ocean floor) and eventually gets compressed into rock (over millions of years). Basically back to where it came from.

Remember orbit is not like a flying airplane. Those things are going so fast friction forms a plasma that eats away at the object as it decelerates. If you can expose more surface area that effect will eat away at much more of the object. So you design it to have through-bolts or other fastener designs where the outermost portion of the fastener burns off quickly, allowing the whole assembly to rapidly disassemble and vastly increase surface area.