Computing by hand as a paid occupation · Ceded (since 1962)

Before John Glenn's orbital flight, NASA asks Katherine Johnson to run by hand the same equations the IBM 7090 had already computed, and Glenn agrees to fly once her figures match.

For a century the word computer named a person, first at observatories and ballistics offices, then in the computing sections of the NACA and of NASA. February 1962 marks the reversal: the machine produced the answer and the person was called in to check it, not the other way round. Within a few years the sections were closed and their members became programmers, engineers or nothing. What is not ceded is choosing which equations to solve, judging whether an answer is plausible, and taking responsibility for a number that a life depends on. Glenn did not ask the computer whether it could be trusted, he asked a person.