Which category of objects often poses the longest-term debris hazard because they typically lack the necessary propulsion capability?

Answer

Spent propellant tanks and adapter rings from the launch vehicle

The large, inert hardware from the launch vehicle, such as spent stages or propellant tanks, often remain in high orbits for decades because they lack the propulsion systems required to maneuver into a 'graveyard orbit' like functioning satellites.

Which category of objects often poses the longest-term debris hazard because they typically lack the necessary propulsion capability?
Spaceexplorationrocketssatellitesspacecraftlaunch