Walter S. McAfee is the African American mathematician and physicist who first calculated the speed of the moon. McAfee participated in Project Diana in the 1940s - a U.S. Army program, created to determine whether a high frequency radio signal could penetrate the earth's outer atmosphere. To test this, scientists wanted to bounce a radar signal off the moon and back to earth. But the moon was a swiftly moving target, impossible to hit without knowing its exact speed. McAfee made the necessary calculations,
and on January 10, 1946,
the team sent a radar pulse through a special 40-feet square antenna towards the moon. Two and a half seconds later, they received a faint signal, proving that transmissions from earth could cross the vast distances of outer space. Official news of this scientific breakthrough did not include McAfee's name, nor was there any recognition of the essential role he played. But Americans could not have walked on the moon had it not been for Walter S. McAfee and his calculations.