The term Big Science is usually attributed to an article by Alvin M. Weinberg, the director of Oak Ridge National Laboratory, (producer of The United States Military grade Uranium). This was in response to US president, Dwight D. Eisenhower's 1961 farewell address, in which the departing U.S. president warned against the dangers of what he called the 'military-industrial complex' and the potential domination of the Federal government by large corporations and military industrialists.
It basically alludes to scientific projects that require the resources of an entire modern nation to accomplish national strategic goals. US nuclear missile technology and the Apollo Space program being two interlinked projects. The term 'two edged sword' is tailor made to describe the scientific advances generated by these huge technological feats.