Novel Sensing and Detection

With the blue water threat of free-ranging, nuclear-armed Soviet submarines coming to a head in 1971, the Department of Defense (DoD) assigned DARPA a singular mission: Revamp the U.S. military’s anti-submarine warfare (ASW) capabilities to track enemy subs under the open ocean where the U.S. Navy’s existing Sound Surveillance System (SOSUS) was falling short. At the time, the U.S. Navy was already working on what would become its Surveillance Towed Array Sensor System, or SURTASS, through which surface ships towed long, mobile arrays of sensors to listen for submarine activity. Telemetry and data-handling issues greatly limited the system’s capabilities.

That’s when DARPA committed funds for the LAMBDA program to modify oil-industry-designed seismic towed arrays so they could detect submarine movement. DARPA-funded scientists began experiments at submarine depths, and soon generated spectacular results. In 1981, the DoD gave quick approval for production of a LAMBDA-enhanced SURTASS array, without requiring further study, a highly unusual decision for a program that had experienced a major technology shift late in the game. The system—which with DARPA participation would become enhanced by way of leading-edge computational tools, satellite-based data linkages, and computer networking—would become the Navy’s go-to method for tracking mobile Soviet subs for the remainder of the Cold War. By 1985, Secretary of the Navy John Lehman was so confident in his force’s ability to keep tabs on elusive Soviet boomers (a nickname for ballistic missile submarines), he declared that in the event the Cold War turned hot, he would attack Soviet subs “in the first five minutes of the war.”

Leveraging past DARPA developments in laser-based versions of RADAR—known as LIDAR, short for light detection and ranging—the High-Altitude LIDAR Operations Experiment (HALOE) provided unprecedented access to high-resolution 3-D geospatial data. First deployed to Afghanistan in 2010, HALOE was one of several DARPA advances directly supporting the warfighter that earned the Agency the Joint Meritorious Unit Award from the Secretary of Defense in 2012.

For many years beginning in 1994, DARPA provided substantial funding in the then emergent arena of micro-electro-mechanical systems (MEMs). With lineage in microelectronics technology, MEMs researchers cleverly adapted standard semiconductor-fabrication methods to fabricate miniature mechanical structures such as flexible membranes, cantilevers, and even trains of interdigitated gears, and integrated these with electronics to create a menagerie of MEM systems. Among the target deliverables for the DoD were inertial navigation devices for smartening up weapons and tracking soldiers, miniaturized “laboratories on a chip” for such uses as detecting biological weapons in the field, and optical switches and displays. DARPA’s patient support is widely credited with adding consequential momentum to the field of MEMs, which since has blossomed into a multi-billion dollar market in the military and civilian sectors.

DARPA launched the Microwave and Analog Front End Technology (MAFET) program in 1995 as a follow-on to the Millimeter Wave Monolithic Integrated Circuits (MIMIC) program, which began in 1987. MAFET aimed to significantly reduce non-recurring costs for microwave and millimeter-wave sensor systems for military applications.

Before DARPA was established, a President’s Science Advisory Committee panel and other experts had concluded that reliable ballistic missile defense (BMD) and space surveillance technologies would require the ability to detect, track, and identify a large number of objects moving at very high speeds. Responding to these needs, DARPA in 1959 initiated a competition for the design and construction of a large, experimental two-dimensional phased array with beam steering under computer control rather than requiring mechanical motion of the antenna.

Known as the Electronically Steered Array Radar (ESAR) Program, the focus of the effort was to develop low-cost, high-power tubes and phase shifters, extend component frequency ranges, increase bandwidth, apply digital techniques, and study antenna coupling. DARPA pioneered the construction of ground-based phased array radars such as the FPS-85. This radar system had a range of several thousand miles and could detect, track, identify, and catalog Earth-orbiting objects and ballistic missiles. The FPS-85 quickly became part of the Air Force SPACETRACK system and was in operation from 1962 until the SPACETRACK unit was deactivated in early 1967.