know that getting into space is a tricky business,  even with half a century of experience and plenty  

of advanced technology helping us out. But in the early days of spaceflight,  

it was a lot harder -- in fact, the paths of  many of those first missions were calculated  

entirely by hand, by people like Katherine  Johnson, a mathematician who helped plan the  

missions that sent the first Americans into space  and then into orbit, and finally to the Moon.  

Johnson was born in White Sulphur Springs,  West Virginia in 1918. An excellent student  

who was especially good at math, she was  ready for high school at the age of ten.  

But in White Sulphur Springs, African American  students couldn't attend high school, so the  

family moved to another part of the state, to a  town called Institute. There, she and her siblings  

continued their education -- though her father  remained in their original hometown to work.  

When Johnson started college at 15, one of  her professors recognized her math skills,  

and encouraged her to pursue the  subject. The professor created a  

course in analytic geometry -- the study of  shapes using coordinates -- just for her.  

She became known for asking lots of questions  in class -- not because she didn't understand,  

but because she could tell other people  didn't even understand enough of what was  

going on to ask what they needed to know. At 18, Johnson graduated college with degrees  

in French and Mathematics. She'd originally planned to  

earn a graduate degree, too, but when  her husband was diagnosed with cancer,  

she took up teaching to support her family. Later, at a family gathering, a relative  

mentioned that the National Advisory Committee  for Aeronautics, or NACA -- the organization  

that would later become NASA -- was looking  specifically for African-American women  

to act as “computers.” NACA needed these  skills to check engineers' calculations in  

the Guidance and Navigation Department. Her work at NACA started in 1953 as one of  

these so-called “computers in skirts,”  reading data from the black boxes of  

airplanes and making calculations based on  that data, to learn how the flight went.  

But she still had a lot of questions  -- how did these calculations work,  

and why were they so important? She started going to the researchers' meetings  

to find some answers. Some people protested  at first, since women weren't usually invited,  

but Johnson pointed out that there was no  rule against it, and was allowed to stay.  

When the all-male Flight Mechanics Branch -- which  studied how airplanes fly -- needed extra help,  

Johnson was selected because of her  knowledge of analytic geometry.  

At first, it was meant to be a temporary  transfer, but her skills proved valuable,  

and she remained on the team until she  moved to the Spacecraft Control Branch,  

which was responsible for designing space  missions and calculating trajectories.  

One of those missions was Freedom  7, Alan Shepard's flight that made  

him the first American in space. The goal was just to get him to space  

and back -- a simple-looking parabolic arc --  but there were lots of factors to consider.  

NASA told Johnson where they wanted Shepard  to land, and she worked backward from there.  

She had to take into account things like  how high they wanted the capsule to go and  

the burnout conditions -- that is, the velocity  and position of the rocket when the fuel ran out  

and it entered free fall back to Earth. Shepard's space flight lasted 15 minutes  

and 22 seconds and traveled 486  kilometers from its launch point.  

And thanks to Johnson's calculations, he splashed  down right on target in the Atlantic Ocean, where  

NASA had a helicopter ready to fish him out. By the time NASA was ready to send John Glenn  

into orbit, they were using digital  computers to do the calculations.  

But even then, they asked Johnson  to confirm the computer's results,  

planning how Glenn would go from launch to  three elliptical orbits, then fire rockets  

to slow himself down and land in the ocean. Johnson went on to contribute to NASA's famous  

Apollo 11 mission, but this time, the planned  end point wasn't the ocean. You guessed it,  

the end point was the Moon. This presented a whole new set of  

challenges for calculating the trajectory,  because the Moon is a moving target,  

the kind you really didn't want to miss. NASA also needed Apollo 11 to land smoothly  

on the Moon, away from cliffs and craters. So the rocket had to leave Earth during a specific  

launch window, a time when the Moon would be  orbiting Earth right in the rocket's path.  

And the trajectory wasn't just a  straight shot from the Earth to the Moon,  

either. NASA's computers -- and again, Johnson  -- had to factor in the Moon's gravitation and  

plan for the rocket's path to be skewed by it. With Johnson's calculations to back them up, the  

mission was launched, and on July 20th, 1969, Neil  Armstrong took those first steps on the Moon.  

Johnson retired from NASA in 1986, and while  she no longer calculates altitudes, burnout  

velocities, or launch windows, she hasn't stopped  counting -- August 26th is her 97th birthday!  

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