The odyssey of geodesy

Professor Chris Rizos is passionate about promoting what he refers to as ‘modern geodesy’ and raising its profile on the global stage. Having provided over 20 years of unstinting service to some of the most prom- inent international geodetic organisations, Professor Rizos is perfectly placed to take us on a brief odyssey into modern geodesy:

Professor Chris RizosWhat is modern geodesy?

Geodesy has traditionally been interested in working out the size and shape of the Earth, the rotation of the Earth in space and understanding the Earth’s gravity field – all important applied science topics. With the emergence of the Space Age, however, we now have technologies that do these tasks at a level of accuracy far beyond what we need for surveying, so what started as an applied science related to surveying has now morphed into something much more: I call this modern geodesy.

Why is modern geodesy important?

Modern geodesy can be considered an Earth observa- tion science. We can now measure not only coordinates, gravity and length-of-day, but we can also measure the variations with time of these (and many other quanti- ties) so we now have to think in four dimensions. For example, anything that’s related to a distortion in the shape of the Earth or a change in its gravity field can now be measured using geodetic techniques. GPS is our primary geodetic tool, but there are other satellite technologies as well.

As a service science, geodesy sits behind the other more visible sciences, providing tools and datasets that help geoscientists monitor global change (including natural and climate change), changes in the environ- ment (to ice sheets and atmosphere etc) and geohaz- ards (i.e. volcanos and earthquakes). The engineering side benefits too, but we apply the measurements and technologies in a more pragmatic way. Surveyors and civil engineers use modern geodesy on everything from small-scale building work to international mapping projects.

...but actually seeing cool space technology being incorporated into real measurement systems which have considerable global impact

Professor Chris Rizos

What kind of impact has UNSW had on the global geodesy world?

Considerable! Our impact has largely been through leadership roles in international and national associ- ations going right back to the 1960s. Professor Peter Angus-Leppan, a former Head of the School of Survey- ing here at UNSW, was the first president of the Inter- national Association of Geodesy (IAG). I am the second president of the IAG with a UNSW connection. We’ve also had staff hold leadership positions on the Interna- tional Society for Photogrammetry and Remote Sensing; the International GNSS Service; Multi-GNSS Asia; and many others.

How has international service enriched your career?

Working in international service goes well beyond the traditional academic profile – which tends to focus on publishing papers, raising grant income, and the like. It’s given me a lot of pleasure because I’ve been able to look at, and even influence, the ‘big picture’. It’s very satisfying to be part of the evolution of geodesy, not just in the theoretical sense, but actually seeing cool space technology being incorporated into real measurement systems which have considerable global impact.


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