one was launched. According to an official NRO history, "In the first 20 years of reconnaissance satellite program activity in the United States, Quill was … the only satellite of any nature to proceed from start to finish with a perfect record in launch, orbital operations, readout, and recovery". To limit the need for strong data-transmission signals from the satellite, ground stations having a very large signal-capture area (antenna area) and subsequent narrow-beam receiving directivity were desired. Available facilities with large-dish antennas capable of rapidly slewing to follow a satellite across the sky existed at New Boston, NH, and at Vandenberg AFB on the California coast. Those locations were also used for up-communication of radar turn-on and turn-off and other payload control commands. The side-looking antenna required for SAR operation was mounted nearly flush along one side of the Agena's cylindrical body. In orbit, the body was rolled so that the beam was directed at a vertical angle of 55° from horizontal. From orbital altitudes varying around 130 nautical miles (nm), the beam illuminated the earth's surface along a 10 nm-wide swath generally 160 nm distant and centered about 93 nm to the left of the vehicle's ground track. The 0.006-radian-wide along-track beam illuminated 0.56 along-track nautical miles at a time, continuing to collect returns from each scene point while traveling that far along the earth's surface, that much data per scene element to be collapsed ("focused"), during later signal processing, into a single measure ("image") of the strength of return from that scene element. Launch After launch on 21 December 1964, data collection was commanded intermittently during both day and night for four days by ground controller's commands via the tracking stations. The Quill SAR's operation was therefore restricted to vehicle locations within the about 900-statute-mile (1490 km) maximum line-of-sight distances from those two ground stations. Such regions were almost totally within the U.S., but could cover some of Canada from the eastern station and some of Mexico from the western one. Operating times were further restricted, by the controllers, to areas within NORAD (North American Air Defence) territory, avoiding illuminating or imaging any Mexican territory, but that was not done in regard to Canada, the U.S.'s partner in NORAD. To avoid calling excessive attention to this unique vehicle, its orbital path was similar to one then being used by U. S. photo satellites. Since launch from Vandenberg AFB