We, men of knowledge
In 1978, the NASA scientist Donald Kessler predicted that a collision between two pieces of space junk could trigger a cascade of further impacts, creating dangerously large amounts of debris.
Kessler pointed out that when the rate at which debris forms is faster than the rate at which it de-orbits, then the Earth would become surrounded by permanent belts of junk, a scenario now known as the Kessler syndrome.
By some estimates, the Kessler syndrome has already become a reality. In January 2009, a collision between the Iridium 33 and Cosmos 2251 satellites created just this kind of cascade. Two years earlier, the Chinese military tested an anti-satellite weapon by destroying one of its own satellites called Fengyun 1C. Both incidents took place at altitudes of about 800 km. (…)
Various ideas have been floated for removing space junk, most of them hugely expensive.
Today, James Mason at NASA Ames Research Center near Palo Alto and a few buddies describe a much cheaper option. Their idea is to zap individual pieces of junk with a ground-based laser, thereby slowing them down so that they eventually de-orbit.
