Defining Innovations

By the late 1950s, it was clear that existing radar technology was unable to detect, track, and guide U.S. surface-to-air missiles against multiple attacking enemy aircraft or missiles. To address this critical challenge, APL developed a “phased array” radar system for the Navy. The system was designed to provide the near-instantaneous scanning, tracking, and closed-loop guidance needed to defend against simultaneous aircraft and missile raids. Advances led to a prototype phase shifter—a key element of a phased array—along with the radar-beam control algorithms and software and the complex signal processing needed to discriminate real targets from environmental clutter and signal noise. By 1969, APL had built and tested a prototype phased array radar system known as AMFAR (advanced multi-function array radar). This system was the precursor to the AN/SPY-1A, a key enabler of the Navy’s Aegis Combat System. Today, the legacy of APL’s AMFAR lives on in the AN/SPY-1 radar and its successors, which provide the continuous radar coverage needed to defend the U.S. Navy, as well as the navies of Japan, Australia, Spain, and South Korea, against multiple, simultaneous aircraft and missile attacks.

In the early 1970s, the Navy sought APL’s help to field a long-range nuclear cruise missile that could navigate heavily defended environments and strike strategic targets. Such a weapon required a means to verify and adjust its location en route to a target. To solve this problem, APL engineers applied terrain contour matching (TERCOM) technology, which matches the missile’s onboard altimeter readings to elevation maps stored in its computer. APL developed algorithms to reliably predict what ground areas would provide correct matches. When greater accuracy was needed for conventionally armed Tomahawks, APL developed the performance prediction algorithms needed to apply digital scene matching area correlator (DSMAC) technology, which further increased accuracy by comparing images taken by an onboard camera to scenes stored in the missile computer. The conventional land-attack Tomahawk enabled by TERCOM and DSMAC became the world’s first long-range, autonomous, precision-guided weapon, and it has been a key element of the U.S. arsenal since the early 1990s. TERCOM and DSMAC remain operational on Tomahawk for use when GPS is not available.

Faced with the threat of highly advanced air and missile attacks against its battle groups in the 1980s, the U.S. Navy called on APL to develop a real-time sensor networking concept called the Cooperative Engagement Capability (CEC), which would combine and integrate radar measurements of multiple ships into composite tracks that would be more accurate and persistent than tracks generated by individual ship radars. The system provided ships in a battle group with an identical radar picture of threats in intense hostile electronic jamming environments, allowing ships to fire and guide surface-to-air missiles against targets using data from the radar systems of other ships or aircraft, even when the firing ship’s own radar could not detect or track the targets. Today CEC is installed in more than 120 U.S. Navy ships and airborne early warning aircraft and provides the foundation for the next-generation Naval Integrated Fire Control – Counter Air (NIFC-CA) capability, which allows Navy ships and aircraft to engage threats well beyond the horizon.

The high cost of the space shuttle program in the late 1970s and 1980s significantly reduced funding for NASA’s planetary science missions, which at the time typically cost more than $1 billion each. Convinced that it could design, build, and operate missions well below that threshold, APL proposed a generation of ambitious, low-cost planetary missions. In its first opportunity to prove the viability of its low-cost approach, APL developed the Near Earth Asteroid Rendezvous (NEAR) mission, the first to orbit an asteroid. APL designed and developed the spacecraft more rapidly and less expensively than had ever been attempted for a planetary science mission; it was a stunning success. After a year of orbiting the asteroid Eros, APL engineers softly landed the spacecraft on the asteroid—where it continued to transmit science data back to Earth for two weeks. The success of the NEAR mission established APL as a national leader in low-cost planetary exploration and inspired the creation of NASA’s Discovery and New Frontiers programs, paving the way for the profound scientific discoveries resulting from APL’s MESSENGER Mercury orbiter, launched in 2004, and New Horizons, which launched in 2006 and completed its historic flyby of Pluto in 2015.

APL responded to the critical challenge of proliferating ballistic missile threats, leading the development of the transformational system needed to demonstrate Ballistic Missile Defense (BMD) from the sea. The resulting experiments proved that BMD technology could be integrated with a Navy weapon system to “hit a bullet with a bullet” in space from the sea. APL’s critical contributions opened the door for the Navy’s central role in BMD. The resulting impact is felt far beyond our nation’s shores as BMD now provides enduring defense at sea and ashore across the globe.

For more than a decade, APL engineers and scientists developed game-changing concepts and technologies to prove that it was possible to defend our planet from an asteroid on a potentially catastrophic Earth-impact trajectory. APL established the technological basis for planetary defense; solidified the domain as a research and development area at the federal level; played key roles in defining and exercising interagency and international coordination responsibilities; and captured worldwide attention by successfully completing the DART mission, the first in-space demonstration of planetary defense technology.