Project Quill: Radar in Space
Recently declassified NRO documents shed more light on early experiments in radar imaging reconnaissance satellites
The period from the mid-1950s to the mid-1960s was a time of extraordinary developments in remote sensing for overhead photographic intelligence. With the creation of the U-2 and A-12 spyplanes, the CORONA-series reconnaissance satellites, and the Ryan Model 147-series unmanned reconnaissance drones, the U.S. had an impressive capability to photograph virtually any denied territory in the world. Crisis after crisis, from the Suez to Cuba, had shown the value of such systems. However, national technical means (NTM) photographic systems of the day had two common shortcomings: bad weather and darkness.
During the first decade of U.S. operations roughly a third of the photographs taken through NTM were useless due to clouds or weather obscuring the targets. Seasonal climate patterns, along with foliage cover (jungle, forest, etc.) made the development of sensor technology that could provide all-weather, day and night coverage of targets in denied territory both a challenge and a long-term requirement for U.S. intelligence agencies. One promising technology was synthetic aperture radar (SAR), which created photograph-like pictures of terrain, structures and even vehicles. However, unlike film or plate-based photography, which had existed since the 1830s, SAR was a new, immature, and untried technology.
Unlike the earlier U2/A-12 spyplanes and Corona photographic satellites that were based on evolved technologies, SAR would require a dedicated testbed to evaluate it from the “high ground” of low-Earth orbit (LEO). Enter Project Quill. The new National Reconnaissance Office (NRO) ran Quill from 1962 to 1969 to evaluate the potential benefits and challenges of using SAR as a sensor from LEO. Never intended to create an operational capability, Quill was in fact cloaked in more secrecy than most earlier NRO programs. The testbed spacecraft was based upon existing hardware and systems from Corona, both to keep costs down and cover Quill even within the intelligence community itself.
The two Quill spacecraft (a primary – Vehicle 2355, and backup – Vehicle 2356) were built using the same Lockheed RM-81 Agena-D upper stage as the Keyhole 4 (KH-4) version of Corona. The radar, designated KP-II, was a heavily modified Goodyear AN/UPQ-102 pulsed-Doppler system from the Air Force’s RF-4C Phantom II reconnaissance jet. The KP-II’s antenna was two feet wide and 15 feet long, mounted flush with the Agena-D’s skin and projecting 2 1/2 inches above it. The radar was designed to detect objects as small as 10 feet by 80 feet, was battery powered, and designed with a service life of just 96 hours. Another key feature of Quill was a dual readout system, composed of a 70 mm film-return camera system to record the radar readout, and a radio data link to evaluate real-time downlinking of the KP-II data. The film take-up system and recovery capsule were the same basic hardware used on the Corona satellites, which were normally recovered in mid-air north of Hawaii. Analysis of the Quill data would be performed by the National Photographic Intelligence Center (NPIC) in Washington, D.C.
The entire package was launched using an SLV-2A Thrust-Augmented Thor (TAT) booster from Vandenberg Air Force Base, CA on Dec. 21, 1964 on Project Quill’s one-and-only mission. One key point of the Quill mission was that all the test targets for the KP-II radar were in the continental United States. Presidential concerns over the vulnerability of satellite radio data links in LEO being intercepted and exploited had led to restrictions on their use in NTM systems since 1960. Therefore, the Quill radar and data link were only turned on over specific planned areas chosen to represent a variety of potential targets. Everything from structures and ground antenna farms to naval vessels and aircraft were imaged prior to the film return capsule being ejected. The Agena-D was destroyed when it reentered the atmosphere on Jan. 11, 1965.
The performance of the KP-II was actually quite good, even being able to detect moving targets under some conditions. In addition, Quill proved particularly adept in detecting targets with large numbers of reflective metal shapes and structures, like industrial areas, scrap yards, harbors and vehicle assembly areas. In fact, the post-flight analysis by the NPIC indicated that purpose-built SAR radar with a ground/object resolution of 10 feet/3 meters was entirely feasible. However, the Quill mission also revealed the limitations of 1960s technology in making SAR into an operational NTM sensor. Neither the film nor data linked images were of particularly good quality, and the need for real-time transmission of reconnaissance data was growing rapidly. By 1977, film-based imaging NTM systems were in the decline, and digital systems on the rise.
Today, SAR satellites are a standard remote sensing tool, both for national security and commercial applications. Systems like Lacrosse continue to provide vital early warning, targeting and monitoring services of the entire globe, all of which owe their existence to the humble NRO testbed known as Quill. For more information on Project Quill, and to see some of the declassified documents, go to http://www.nro.gov/foia/declass/QUILL.html.