Researchers say parts of the Moon will be set aside as graveyards for defunct satellites.
Lunar orbit is expected to become crowded as space agencies and companies expand activities.
Old satellites cannot burn up, forcing operators to crash them onto the surface.
Uncontrolled impacts could damage scientific instruments and historic sites.
Experts favour designated impact zones or deep craters to contain debris.
International agencies are now working on rules to manage lunar satellite disposal safely.
