While there, he also took on the role of Visiting Principal Scientist for Oak Ridge National Laboratory, United States Atomic Energy Agency from 1976 to 1977.
[7] He bombarded materials with nuclear particles to find new information about their properties, including determining the location of trace elements in mineral grains, deficiencies of chromium in human blood, the quality of uranium ores, the structure of solar absorber surfaces, properties of semi-conducting materials, and trace analysis of air pollutants.
At News Corporation, Clark served as the president of technology, where he was responsible for transforming its assets for program creation and media delivery from analogue to digital platforms, across film, print, and television.
Clark then moved on to become the president and chief operating officer of Loral Space and Communications, the world's largest commercial satellite manufacturer.
Centre for Ultrahigh Bandwidth Devices for Optical Systems since 2011, a Councillor at the University of Sydney Physics Foundation since 2013, chairman of the Commercial and Philanthropic Development Board, Australian National University's School of Physical Sciences and Engineering since 2013, and a board member at Questacon National Science and Technology Centre since 2014.
[3][6] In 1979, Clark was awarded the Pawsey Medal by the Australian Academy of Science, in recognition of his contributions to the field of mineral physics.