Gladys West Built the Math GPS Depends On
West helped refine an Earth model accurate enough to enable GPS positioning. That work demanded patience with tides, atmosphere, imperfect readings, and an Earth that refuses to be simple.
Gladys West grew up on a farm in Sutherland, Virginia. She watched her parents work tobacco fields and tend livestock, and she decided she would not spend her life doing the same. The decision carried real weight. An African American girl born in 1930 in the rural Jim Crow South had limited routes out. One route was education. West studied hard enough to rank first in her class at Dinwiddie Training School. That ranking mattered because it came with a scholarship to Virginia State College—the only way she could afford to attend. She converted grades into an exit.
At Virginia State, she considered majoring in Home Economics. Her teachers pushed her toward mathematics. Harder, they said, meaning fewer people would stick with it. The work suited her. “I knew that I liked the orderliness of math, the preciseness of it, the neatness of it,” she said in a 2020 interview. She graduated in 1952, taught high school math briefly, then returned for a master’s degree in mathematics, finishing in 1955.
Her mentors at Virginia State were John and Louise Hunter. John Hunter had a PhD in physics from Cornell. Louise Hunter was the first African American woman to earn a doctorate from the University of Virginia. They pushed West beyond high school teaching, and when she learned about a position at the US Naval Proving Ground in Dahlgren, Virginia, they urged her to apply. In 1956, she was hired as a mathematician, one of only four Black employees at the installation.
Dahlgren had the most powerful computers in the country during the 1950s. The Mark II, the Mark III, then the Naval Ordnance Research Calculator built by IBM. These machines filled entire rooms. Before them, West had used Marchant desktop calculators to compute range tables. The new machines offered speed, but they required a new kind of labor. Programmers wrote instructions in zeros and ones. West would draft her instructions, then hand them to keypunchers who punched the code onto cards. A separate group verified the cards. Then the cards went to operators. Sometimes West would get a call asking if she wanted to watch the run to see whether the program would crash or finish. When errors appeared, she combed through lines of data to find them. No error messages pointed the way. You traced, rechecked, compared, and reran.
The social conditions at Dahlgren were segregated in practice even after federal hiring discrimination was officially banned. Black employees could not stay at the same hotels as white colleagues during work travel, which meant they were often left out of conferences and professional development that could lead to project leadership. West and other Black mathematicians lived in dormitories on the naval grounds because the surrounding Virginia communities would not house them. “We had come to Dahlgren in the early 1950s, and we were the ones integrating the Naval Proving Ground,” she said. “So we knew there would be a lot of hardships and discrimination we were going to face.” She stayed for forty-two years.
The work that made West’s reputation began in the 1970s and extended through the 1980s. The Navy wanted to use satellite data to map locations on Earth with extreme precision. This required geodesy, the mathematics of estimating the Earth’s shape. A high school globe suggests the Earth is a smooth sphere. It is not. It is an oblate spheroid, flattened at the poles. Even that is too simple. The planet’s density varies. Ocean currents pull on the water. Tides rise and fall. The atmosphere bends signals. Satellites send imperfect readings. To locate anything with GPS accuracy, West and her colleagues had to model all of this and correct for it, repeatedly.
West led projects processing radar altimeter data from satellites named GEOS-3, SEASAT, and GEOSAT. The satellites measured the time it took for a radar pulse to travel from the satellite to the ocean surface and back. That time tells you the distance. But the distance alone is not useful unless you know exactly where the satellite was, exactly what the atmosphere did to the signal, and exactly what shape the ocean surface had at that moment. Each measurement carried noise. The team corrected for atmospheric interference, for tides, for ocean currents, for imperfect satellite orbits. They used Kalman filter smoothing based on a third-order Markov process to clean the data. The goal was sea surface height measurements accurate to less than ten centimeters.
West wrote the algorithms. She calculated, processed, corrected, compared, and verified. When she found an error, she traced it back and reran the computations. “Thinking about the satisfaction of cracking the problem, finding the error, and also the team being excited about it, that was a nice moment,” she said.
The geoid, the mathematical model of Earth’s gravity field at mean sea level, had to be refined constantly. West’s group did not have the computational frameworks available today. They worked with satellite data, statistical algorithms, and the patience to iterate until the numbers held. The resulting Earth model became one of the foundations for GPS positioning. The Air Force recognized her contribution in 2018 with a Space and Missile Pioneers Award, citing her “increasingly refined calculations for an extremely accurate geodetic Earth model.”
She kept working through the limitations at Dahlgren. Women were rarely promoted to supervisory roles. Black employees still faced barriers to travel and professional visibility. West earned a master’s degree in public administration in 1973 while still employed at Dahlgren. After she retired, she completed a PhD in public administration from Virginia Tech in 2000. She was seventy years old.
Her teachers at Dinwiddie Training School had called her “college material.” Her mentors at Virginia State pushed her into graduate mathematics and federal research. Ralph Niemann, her manager at Dahlgren, opened the door to Black mathematicians when few other federal installations would. None of this happened automatically. Each step required someone willing to see past the barriers and a person willing to keep working once inside.
West published a memoir in 2020 titled It Began with a Dream. She and her husband Ira, also a mathematician, have a scholarship fund at the Dahlgren Museum supporting first-generation college students from King George County. She is ninety-four years old. The GPS receiver in your phone relies on the precise Earth modeling she spent decades refining—correcting for tides, atmosphere, imperfect readings, and an Earth that refuses to be simple
