Defence science can embrace the whole gamut of scientific disciplines, but is distinguished from other divisions of science by its applied nature. In its more abstract forms it may appear to support pure research, but an application is always intended and such apparently pure research should more properly be called 'strategic research'. Since, however, the word 'strategic' has another connotation in this field we shall treat all defence research as 'applied research'.

The applied nature of the research, and associated security requirements, have consequences for the individual scientists engaged in the work. It is well known that the reputations of academic scientists are made by publication in the 'open' literature. This is only occasionally available to defence researchers. Additionally, the applied nature of the work leads to a requirement for large project teams in which individual achievement is sometimes difficult to identify. While not different in this respect from industrial research, it is different from other public-funded research and has often led to false judgments of the quality of defence science.

A consequence for this chapter is that it has not been possible to give full credit to the many participants in discoveries and developments. It has often only been possible to give the names of the leaders of groups with whom we hope the team members will be able to find identification. Security issues have also limited some of the detail, and indeed some of the topics. Just as defence science is directed research aiming directly at national defence, and for which any spin-offs are no more than that, so is defence technology similarly directed, deriving either from defence science or from the transfer of engineering advances from the civil domain. Scientific and engineering discoveries and developments which might aid defence incidentally by strengthening the economy or infrastructure are therefore not discussed here.

Defence technology has ancient roots, but the formal existence of defence science organizations really begins at or about the First World War. Defence technology or engineering, on the other hand, has been a continuous activity of the military, although in recent times there has been a shift to dedicated civilian groups.

It is often difficult to separate the introduction of technology from the indigenous generation of it. Except for the most simple things, or turn-key operations, some innovation on site is almost always necessary. Both need to be addressed, but the emphasis will be on innovations.

Defence science and technology is government funded. It follows that, in quantity at least, its ebbs and flows reflect more or less the same economic and social factors that affect civil science and engineering. On top of these, however, there are special factors, such as the perception of threat, and (variable) attitudes to self-sufficiency.

Australian Academy of Technological Sciences and Engineering