Problems arise when people send smaller satellites into higher orbit. At higher altitudes, satellites encounter exponentially less atmospheric drag, which is the main force that pushes satellites to lower altitudes and eventually back to Earth. Unlike their bigger cousins, small sats don't have the technology to drive back down, either. Researchers may develop this tech in the future. For now, however, once small satellites get way up there, they're stuck. At that point, they're dangerous.