The first serious attempt to listen for possible radio signals from other civilizations was carried out at the National Radio Astronomy Observatory in Greenbank, West Virginia, in 1959 and 1960. It was organized by Frank Drake, now at Cornel University, and was called Project Ozma, after the princess of the Land of Oz, a place very exotic, very distant and very difficult to reach. Drake examined two nearby stars for a few weeks with negative results. Positive results would have been astonishing because as we have seen, even rather optimistic estimates of the number of technical civilizations in the Galaxy imply that several hundred thousand stars must be examined in order to achieve success by random stellar selection.
首次正式尝试收听别的文明社会可能发出的无线电讯号，是1959年到1960年间，在西弗吉尼亚州格林班克国家射电天文观察台进行的。这项工作由现在康奈尔大学的弗兰克·德雷克主持，被称作奥兹玛工程。它系用奥兹国——一个富于异国情调、十分遥远、极难抵达的地方——的公主的名字命名的。德雷克用数周时间探测了附近的两颗恒星，未有结果。倘若能有发现，倒是会令人大为震惊，因为，正如我们所知，即使对银河系中的技术文明社会的数目作相当乐观的估计，若要未经选择便能搜寻成功，那非得对数十万颗恒星进行探测不可。
Since Project Ozma, there have been six or eight other such programs, all at a rather modest level, in the United States, Canada and the Soviet Union. All results have been negative. The total number of individual stars examined to date in this way is less than a thousand. We have performed something like one tenth of one percent of the required effort.
从奥兹玛工程起，已有六个或八个类似的项目在美国、加拿大和苏联进行过，规模均有限。其结果也是一无所获。至今像这样探测过的星球不到一千，相当于需要探测的星球总数的百分之一中的十分之一。