Today — Aug. 26 — is Katherine G. Johnson’s 100th birthday. Her math powered some of America’s first triumphs in human space exploration. Johnson did trajectory analysis for Alan Shepard’s May 1961 mission Freedom 7, America’s first human spaceflight. The first carousel picture here shows that 1961 launch. . At a time when digital computers were relatively new and untested, she famously checked the computer’s math for John Glenn’s historic first orbital spaceflight in February of 1962. Picture 2 shows Johnson at her desk at NASA Langley Research Center (nasa_langley) with a globe, or "Celestial Training Device.” . Those are just two bullet points in a brilliant career that stretched from 1953 to 1986. . “I counted everything. I counted the steps to the road, the steps up to church, the number of dishes and silverware I washed … anything that could be counted, I did.” So said Katherine Johnson, recipient of the 2015 National Medal of Freedom (picture 3). More as always on nasa.gov...