Since the launch of Sputnik I in 1957, more than 6,000 space­craft have been successfully sent into Earth orbit. Each launch – whether successful or not – contributes to the release of human-made debris in Earth orbit. This “space junk” consists of ex­pired spacecraft, spent rocket bodies, mission related objects, and fragmenta­tion debris. A majority of debris remains in orbit indefinitely, but their orbits drift due to the effect of Earth’s atmospheric drag, a force that extends far into space.