gerald-weinberg began at IBM in 1956 at the Federal Systems Division in Washington. He managed operating systems development for Project Mercury (1959-1963), NASA's first human spaceflight program. This experience — managing teams writing mission-critical software in the earliest days of the discipline — gave Weinberg firsthand observation of how programmers actually worked: the social dynamics, the ego conflicts, the communication breakdowns, and the gap between how programming was supposed to work and how it actually worked. These observations became the empirical foundation for psychology-of-computer-programming-1971. The Mercury experience also demonstrated that software quality was inseparable from team dynamics — a thesis that would define Weinberg's entire career.