1985 · Geoid Computation Plots · Work 1199 of 1,871
A naval research office in Virginia on a grey March morning, a tall grey steel cupboard, a large desk covered with wide plotter sheets of blue curving parallel lines, at the right a large pale relief globe on a dark pedestal and a smaller globe on a cabinet, at the desk the woman, a Black woman of fifty-four with dark brown skin, short curly black hair and glasses, in a light beige blazer over a patterned blouse, leaning forward tracing one curve with a pen, her face in three-quarter view, alone in the room.
Who
Gladys West (1930–2026) was a mathematician for the US Navy whose calculations of the shape of the Earth are among the foundations of GPS satellite navigation. She was born Gladys Mae Brown on 27 October 1930 in Sutherland, Virginia, the daughter of Black farmers who owned a tobacco farm. She attended a segregated school, became valedictorian of her class and studied mathematics on a scholarship at Virginia State College, earning degrees in 1952 and 1955. In 1956 the Navy hired her at Dahlgren as one of four Black employees. At first she checked bombing tables with a hand calculator; then she programmed NORC, at that time the biggest computer in the Navy. In the early 1960s she took part in a study of the motion of Pluto relative to Neptune. From the mid-1970s she computed on the IBM 7030 "Stretch" an ever more precise model of the Earth's shape, the geoid, which went into the orbits on which GPS satellites fly today. She managed the radar altimetry project of the Seasat satellite, retired in 1998 after 42 years at Dahlgren and earned a doctorate in 2000. She died on 17 January 2026.
The moment
On 16 March 1985 the Navy photographed Gladys West, then 54, with her colleague Sam Smith at Dahlgren, Virginia, a Navy research station on the Potomac some 50 miles south of Washington. West stands at the table and traces a pen over large plotter sheets full of parallel curving lines; Smith leans over them. On the right stand two globes. The caption says the two were looking over data from the Global Positioning System, which West had helped develop. The computers that produced such curves are not visible in the photograph. For the GEOSAT work the centre acquired two new Control Data mainframes in these years, a CDC 865 for unclassified and a CDC 875 for classified work, reached through terminals; for each orbit of a satellite, geoid heights were plotted against time. In 1986 West issued the specification for processing the data of the Navy satellite GEOSAT, whose radar altimeter readings Dahlgren reduced to the geoid over the oceans. The picture shows her over the curves, Smith seen from behind.
The other side
The Earth model did not serve motorists first. West's own report of 1986 names the primary mission of GEOSAT as improving the gravitational models required by submarine-launched ballistic missiles; the data records were classified and came to Dahlgren on tape by messenger. And the woman whose calculations are now in many phones was, early in her career, sometimes passed over for travel like other Black employees, because Jim Crow laws made it difficult for them to eat in restaurants and stay in hotels with their white colleagues. Recognition came late: only in 2018, when she was almost 90, did her part in GPS become publicly known.
What the sources leave open: The day of the photograph is recorded, not an event; 16 March 1985, a Saturday, is given only by a 2024 Defense Department caption, which also reads the curves as GPS data. What the sheets really show is not recorded. The March light and the colours are inferred, as the photograph is black and white. West's face follows this public-domain Navy photograph; Sam Smith is seen from behind.