Quill was an experimental United States National Reconnaissance Office (NRO) program of the 1960s, which provided the first images of Earth from space using a synthetic aperture radar (SAR). Radar-imaging spacecraft of this design were not intended to be deployed operationally, since it was known that this system's resolution, inferior to that of concurrent experimental airborne systems, would not serve that purpose. Instead, the program's predominant goal was to show whether the propagation of radar waves through a large volume of the atmosphere and ionosphere would dangerously degrade the performance of the synthetic aperture feature. A detailed description of the program has been made available on-line by NRO. Objectives Initially, the primary benefit seen to be offered by radar imaging was its capability for operating at night and also for imaging through clouds or other atmospheric obstructions which absorbed or scattered waves not only in the visible spectrum but also in the nearby infra-red and ultraviolet. But radar also offered the benefit of a received signal that was already an electrical time-function one, ready for immediate radio re-transmission. So that project became a means for a trial of real-time image-data transmission as well as a trial of orbiting SAR. Since the theory and the state of the art for such transmission were well understood, it was realized that existing means for this part of Quill's mission would be inadequate for showing the level of detail needed to evaluate military threats even if the best imagery proved to be as good as expected. Still, not only were their lessons to be learned from trying, but also any success in such transmission was a hedge against failure to recover the on-board film, a problem that had plagued many of the early photo-intelligence satellites. Description Quill satellites were based around the Lockheed RM-81 Agena-D, which also served as the upper stage for orbital insertion. The prime contractor for the orbiting vehicle and its radar payload was Lockheed. To expedite the test, a synthetic-aperture radar designed for airborne use was adapted, by subcontractor Goodyear, to space operation and the long ranges involved, based on criteria developed by the research team at another participating organization whose relationship to Quill has not yet been declassified. Although only one satellite was needed, a backup model and an engineering model were also produced. Because the first one, OPS 3762, accomplished all of the project's test objectives, only that