Issue: May 2004
People
Vale Dr Elizabeth Essex
A significant contribution to global space research
by Peter Dyson
Dr Elizabeth Essex, who died earlier this year following an illness, was an outstanding space physicist. She developed her own research program, achieved international recognition and, as a teacher, inspired many students who went on to develop significant careers of their own. 
Most recently she played a pivotal role in La Trobe University becoming a partner in the CRC for Satellite Systems. With her help, the CRC built and launched FedSat in 2002. It was the first Australian satellite for some 30 years, and it continues to operate today.
Elizabeth was project leader for space-based GPS observations using the receiver on FedSat. This has opened up a new means of studying the outer regions of our atmosphere, as far out at 22,000 km - half way to the 'near-miss' asteroid that flashed past the Earth recently.
Last November the FedSat project received a National Award for Engineering Excellence in recognition of both its engineering and scientific achievements.
Elizabeth studied physics at the University of New England in Armidale, NSW, in the early 1960s where she completed a PhD in ionospheric physics. She then lectured for three years at the University of the West Indies in Jamaica.
On her return to Australia, she accepted a post-doctoral fellowship at James Cook University and soon after, in 1969, moved to a lecturer's position at La Trobe. Four years later she was promoted to senior lecturer.
La Trobe Foundation Professor of Physics, Keith Cole - a world authority on aurora, the ionosphere and magnetosphere - and Dr Eric Butcher were already at La Trobe. I arrived soon after. Together we formed a research group concentrating on ionospheric physics.
With La Trobe in the process of rapidly developing into a first class university, there was money to start research and large mechanical and electronic workshops to build whatever equipment you needed. However, we also needed a field station for our radio and optical instruments away from the radio interference and light pollution of the city.
Elizabeth decided she would study the ionosphere using a technique based on detecting signals transmitted from satellites. This defined her future research career and led to her gaining her very significant international scientific reputation.
The properties of these signals are modified as the signals traverse the ionosphere on their way to the ground. If you can determine these changes, you can use the information to tell you about the ionosphere. From complex GPS navigational systems used by aircraft to maps in modern cars that can suggest the routes you take, the study of these signals has many direct practical applications.
To do this work, Elizabeth set up the first satellite receivers at her home in Research, then pretty much on the outskirts of Melbourne, until we found a suitable block at Beveridge, 35 km north of Melbourne. Her equipment was one of the first instruments located at Beveridge and she continued to operate there until recently.
The Earth's magnetic field is a partial barrier and most of the 'action' in the ionosphere occurs near the poles. Australia's stations in Antarctic and at Macquarie Island are ideally located to study these effects. So, with Keith Cole, Elizabeth then pioneered the expansion of our group's research activities to the stations operated by the Australian Antarctic Division. Over the years, our Antarctic program has been very significant in attracting students keen to combine research with a winter in Antarctica.
The importance of the satellite techniques used by Elizabeth, particularly for the GPS navigational systems, led to the formation of an international group of scientists known as the Beacon Satellite Group. Liz was a valued member of the core group of scientists that planned international conferences and exchanged ideas and results to develop these techniques.
Her contribution was such that on several occasions her expenses were paid for by JPL, the Jet Propulsion Laboratory, which is managed for NASA by the California Institute of Technology.
Elizabeth also helped develop 'microbarographs' to detect wave-like oscillations in the atmosphere at ground level. One idea was to see if you could detect these waves propagating up into the ionosphere. At least two postgraduate students worked on this project. One, Geoff Love, is now Director of the Bureau of Meteorology.
Elizabeth was quiet, gentle, yet very determined. She was widely respected wherever she went. And she was a role model, helping other women students forge their careers in physics.
We have lost an esteemed colleague and friend. We will miss her and extend our condolences to her husband Harvey Cohen, and to her children David, Alexander, Raymond and Zara.
Professor Dyson is Head of the Department of Physics. This is an edited version of the eulogy he delivered for Dr Essex.
back to top
back contents next
|
