Three black astronauts joined hundreds of other mourners Saturday at a memorial service for pioneering African American mathematician and NASA researcher Katherine Johnson. Johnson, who calculated rocket trajectories and Earth orbits for NASA’s early space missions and was later portrayed in the 2016 film “Hidden Figures,” about pioneering black female aerospace workers, died Feb. 24 at the age of 101. "I think about the journey that she's going on now," astronaut Leland Melvin said.