By Jo, UNE Discovery Voyager

Have you ever thought about how Google Maps and GPS work? I think most of us have some vague idea about a network of satellites orbiting Earth and talking to our phones and cars somehow. And that’s more or less accurate, but the usefulness of this technology is, as is often the case, underpinned by a field of science that most people have neither heard of nor considered.

Enter geodesy. Geodesy, or geodetics, is basically the science of the shape and surface of Earth. We all know – at least I hope you all know – that our pale blue dot of a planet is round. Most of the time, we think of it as a sphere. In fact, it’s not quite a perfect sphere, as the rotation of the planet causes a bulge at the equator. Nor is it quite smooth, being covered in mountains, seas, rivers and plateaus, and being affected by slight variations in gravity because of the uneven distribution of mass within it. Due to the gravitational effects of the not-quite-spherical shape of our planet and its variable density, even ‘sea level’ isn’t the same everywhere!

So geodesy is all about mapping the surface of the Earth and its oceans and creating useful models of it. Think of it a bit like surveying – except for the whole planet.

The field of geodesy is old and storied, but we’d like to highlight two of the women who helped map our globe.

Dr Fischer is by an unknown photographer, released by the US Army

First, meet Dr Irene Fischer (1907-2009), a Jewish Austrian mathematician and geodesist. Having fled Nazi Austria to the United States in 1939 with her family, Irene marked papers at MIT and did other odd jobs until her youngest son was old enough for school. Then, in the early 1950s, she got a job in the US Army Map Service, now called the National Geospatial-Intelligence Agency. She spent 25 years in the geodesy branch of the service, earning respect and acclaim from geodesists the world over.

During her early career, Dr Fischer challenged the accepted literature on the oblateness of the earth (that is, basically, how squished it is). The accepted figures had been established in 1924 and she was forbidden from using her own calculations which contradicted them. However, after the launch of the first satellites in the late 1950s, the data collected from them vindicated Dr Fischer’s figures and she was able to retroactively correct her research using her initial calculations.

Dr West was taken by Adrian Cadiz, released by the US Air Force

Dr Fischer’s work also helped determine the parallax of the moon. Lunar parallax is the angular difference between the view of the moon compared to the distant stars in the background from two points on Earth. Her work in this area was pivotal in the progress of NASA’s Apollo program to send humans to the moon.

Additionally, her work on constructing a geoid – a mathematical model of Earth’s surface based on gravity and the planet’s rotation – overlapped substantially with research into the effects of previous ice ages on the shape of the earth.

The other remarkable female geodesist we want to highlight is Dr Gladys West (1930-2026), who passed away only a few months ago. She was a brilliant mathematician whose work in geodesy was fundamental to the development of the Global Positioning System we use today.

Dr West was an African American woman from a poor family in rural Virginia whose mathematical genius and tenacious hard work earned her the scholarships she needed to pursue a different future through education. In 1956, she began work in the Dahlgren division at the Naval Proving Ground, which housed an early computer and was instrumental to the United States’ space race efforts.

Dr West was a pioneer in combining existing techniques of geodesy with the emergent technologies of satellite imaging and computer programming. During the 1970s and 80s, she programmed the 32-tonne IBM 7030 Stretch computer at Dahlgren to provide more precise calculations for the shape of the Earth than had previously been possible.

Dr West also quite literally wrote the book – or at least, the report – on how to use the data from the Geosat satellite, which went into orbit in 1984, to accurately map the Earth’s surface.

The incredible accuracy of the geodetic models of Earth that Gladys West spent her 42-year career constructing, building on the work of those who had come before her, like Irene Fischer, is what made the advent of GPS possible. Because the Earth is not, as we’ve discussed, perfectly spherical, the system of satellites that underpins GPS requires a geoid that is extremely accurate and precise. At such distances and scale, even small inaccuracies could lead to significant errors on the ground.

So, the next time you look at the magnificent photographs from the Apollo missions, think of Irene Fischer and the hundreds of other mathematicians and scientists who contributed to humans getting to the moon and back. And the next time you open Google Maps, spare a thought for Gladys West and her publicly funded research which brought us such a transformative technology.