A lot of space junk is created by design or, better, a lack of design. After a satellite reaches orbit, it goes through a deployment stage. The satellite is separated from the rocket motor, instruments are uncovered, solar panels are deployed, antennas extended. Metal covers, connector plugs and cabling, lens caps and other parts are routinely un-tethered from the rocket and satellite. These objects go into their own undefined orbit.
Every piece adds to a long list of lethal space junk.
I mpact between space junk and orbiting hardware is catastrophic. Traveling at thousands of miles an hour, large and small objects are lethal to anything they meet. Objects no larger than a pencil eraser can bust through a solar panel or tear into the interior of a satellite, destroying wiring and electronic modules, creating more debris. Considering that space is three dimensional, there is a lot of room for space junk to live peacefully with its operational cousins. Orbits are at altitudes from 124 miles to 304,0000 miles.