Space debris, or space junk, refers to the collection of defunct human-made objects in orbit around Earth. This includes spent rocket stages, non-functional satellites, and fragments from collisions. As these objects travel at extremely high speeds (up to 17,500 mph), even small pieces of debris can cause catastrophic damage to operational spacecraft and the International Space Station.
Space debris has been accumulating since the launch of Sputnik 1 in 1957. The problem was first mathematically modeled by NASA scientist Donald Kessler in 1978, who proposed the 'Kessler Syndrome'—a scenario where the density of objects in low Earth orbit becomes so high that collisions between objects cause a cascade, generating more debris and rendering orbit unusable.
With the rise of mega-constellations like Starlink and the increasing commercialization of space, the issue of space debris has become critical. Space agencies and private companies are actively tracking hundreds of thousands of objects. Solutions are being developed, ranging from better satellite end-of-life protocols to active debris removal missions using nets, harpoons, and lasers.