Dr. Gladys Mae West: Charting a Course
- Lindsey Oberhelman
- Apr 2
- 6 min read
The mathematician who created the most accurate maps of Earth and became "the Mother of GPS".
Whenever you need to get somewhere new, all you have to do is type your destination into a maps app on your phone. Within seconds you have directions from your exact location to wherever you want to go. But how is this possible? How does your phone know exactly where you are on the Earth? And how does it know the best way to get from that location to your destination?
Your phone uses an amazing technology called GPS, or Global Positioning System, which depends on a very precise model of the Earth’s surface. For that very precise model, we can thank a mathematician named Gladys Brown West.
Watch the video, or read the blog version below!
Correcting the computers
Gladys Brown West was born in 1930 in rural Virginia. Her family was a mix of sharecroppers and factory workers. Gladys worked hard to win two scholarships to pay for her education at Virginia State University. There, she fell in love with mathematics, and in 1955 graduated with a Bachelor’s and a Master’s degree.
After getting her Master’s, Gladys was quickly hired by the Naval Proving Ground as a computer programmer. She was the second Black woman to be hired, and one of only 4 Black employees at the time. Her job was to program huge computers and check their calculations by hand. This was a tricky task, because scientists were trying to use these computers for research. Because the math was so complicated, West recalled that the computers were wrong “nine times out of a hundred and twenty”, and it was up to her to know enough about the problem to tell when the numbers weren’t right.
With her experience in computer programming and mathematics, West was put in charge of a project called Seasat in 1979. Seasat’s goal was to develop a satellite to orbit the Earth and remotely sense oceans. It was the first satellite ever built that could measure things like ocean topography, meaning the shape of the ocean’s surface. Gladys’s work on Seasat was the jumping-off point for her developing a precise model of the shape of the Earth.
How to pinpoint position
Building a 3D model of the Earth’s shape can’t be that hard, right? We know the planet is basically a sphere. But even if we assume that the Earth is a perfect sphere, we need some math to describe where we are on the planet. Since we all live on the surface of the Earth, our position in space is better thought of in terms of latitude and longitude.
To get an idea for what these words mean, imagine that you’re holding a very long string connected to the center of the Earth. If you stand on the widest part of the Earth, on the equator, we define the angle of the string to be 0 degrees. If you walk towards the North Pole, the angle of the string increases. That angle is called your latitude and it measures how far north or south you are from the equator. We can do a similar thing with moving left and right, with a zero point defined at what’s called the Prime Meridian. That angle is called your longitude. With a specific latitude and longitude, you can define any point on the surface of the Earth!
Now that we have a way to define any two points on the surface of our planet, we can do all sorts of calculations, like find the shortest path between those two points. But this is complicated because the Earth isn’t just a flat plane: it has curvature.
The Earth is slightly squished
We’ve all seen globes, which usually represent our planet as a perfect sphere. But it turns out the Earth is NOT a perfect sphere. At every point, the Earth is experiencing a combination of forces. There’s a force of gravity, pulling everything in, which depends on how the mass of the Earth is distributed. There’s also the centrifugal force pushing things out, which comes from the Earth’s rotation. To get a sense of this force, think about how you feel when you spin in place very fast and your arms want to move away from you. The Earth is spinning, so it experiences the same kind of thing! These forces fight for control over the Earth’s shape. The result is that the Earth is closer to an egg shape, or an ellipsoid, a little fatter around the middle than at the poles!
Scientists since Isaac Newton have speculated that the Earth was an ellipsoid, and eventually measured how egg-like the Earth is. It turns out the difference between the diameter of the Earth at the Equator versus at the poles is 42 kilometers. This may not seem like much, but if you were planning a route without accounting for the difference in curvature, you could be off by at least 22 kilometers.
But the Earth isn’t perfectly smooth either. The presence of mountains and valleys, rivers and lakes, oceans and canyons can all change the best path between two points. Just imagine if your phone sent you wading through a river to get your groceries. There are also slight differences in how the mass of the Earth is distributed, making it a little lumpier in some places than others. For precise measurements of where things are on the surface, we need to take all of these effects into account.
This is where Dr. Gladys Brown West comes in. Thanks to her experience working on Seasat, she was hired to work on Geosat, a satellite programmed to create computer models of the entire Earth’s surface. Dr. West used data from a device called an altimeter attached to a satellite to determine the finer details of Earth’s surface. An altimeter works by bouncing microwave frequency light off the surface of the Earth and measuring the time it takes to come back to the satellite. This gives the precise distance between the satellite and the surface of the Earth.
The most complete map of Earth
For the first time in history, humans had precisely charted the Earth's topography. Gladys West used this data to create a model that combined the mathematics of the ellipsoid shape of the planet with the finer distortions on the Earth’s surface. She then programmed this model into an IBM computer. It wasn’t an easy task. When asked about her programming work, she said, “To tell you the truth, we didn't know anything about computers. It was a long climb to get on board. But it was exciting.” In 1970, this model was used to create a program that could precisely calculate the orbits of satellites, which became the foundation for modern GPS.
After 42 years working on satellites at the Naval Proving Ground, West retired in 1998. But she certainly didn't stop learning---in 1973 she earned a second Master's degree in public administration from the University of Oklahoma, then in 2000 she earned a PhD in public administration from Virginia Tech. And in 2018, Dr. West was recognized for her work by being inducted into the US Air Force Hall of Fame (one of the many awards she's received since her retirement). In her acceptance speech, West hoped her example will inspire another generation of female pioneers. She said, "I think I did help. The world is opening up a little bit and making it easier for women. But still, they gotta fight."
Written by Lindsey Oberhelman
Edited by Manasvi Verma and Taylor Contreras
Video by Caroline Martin and Madelyn Leembruggen
Sources and Further Reading: