Humanity may be building a prison of shrapnel around its own planet, with flecks of paint and twisted metal circling Earth like bullets. This episode examines the Kessler syndrome, beginning with the 1978 paper by NASA scientists Donald J. Kessler and Burton G. Cour-Palais, NORAD employee John Gabbard's discovery that discarded rocket stages were exploding from leftover propellant, and Kessler's decision to borrow asteroid-belt mathematics to model collisions in low Earth orbit.

The hosts explain why useful orbits are narrow shipping lanes rather than infinite space, how 42 percent of cataloged debris traced back to just 19 events, and the three phases of collisional cascade laid out in Kessler's 1991 paper, where a single kilogram at 10 kilometers per second can shatter a 1,000-kilogram spacecraft. They cover anti-satellite tests from the  ...