Kessler syndrome is a theoretical scenario in which the density of objects in low Earth orbit becomes so high that collisions between satellites and debris create a cascade of further collisions. This chain reaction can lead to an exponential increase in space debris, making certain orbits unusable for future satellites. The concept was named after Donald J. Kessler, a NASA scientist who proposed it in 1978. If Kessler syndrome were to occur, it could severely impact space exploration, satellite communications, and global positioning systems, posing significant challenges for future missions and technology.