Elizabeth Annette Essex-Cohen, née Essex, was educated at Grafton High.

[1][2] She subsequently completed a PhD in Physics at Australia's University of New England, investigating ionospheric irregularities under Frank Hibberd, graduating in 1966.

[5] She remained at La Trobe for the remainder of her career, though in 1974 and 1978/9 she had simultaneous positions at the US Air Force Geophysics Laboratory as part of her GPS research.

[5] Her initial work focused on the use of radio wave reflection to study irregularities in the ionosphere.

In the early US Air force's development of GPS (then called Navstar), she was the only Australian involved in the design.