After the Soviet invasion of Afghanistan, shoulder-fired surface-to-air missiles turned the tables on Russia's helicopter gunships and helped end the occupation. In the U.S.-led war in Afghanistan, missile jammers have largely neutralized the threat. But still only a fraction of the aircraft that could find themselves in combat zones is protected by directional infrared countermeasures (Dircm) systems.

A major reason is size. Dircms started out big and have shrunk with time, but are only now becoming small enough to be carried by most military helicopters. And the next step is to make them even smaller—and powerful enough—to defend fast-jet combat aircraft against not only ground-to-air, but also air-to-air missiles.

Anticipating a requirement to protect the Lockheed Martin F-35 Joint Strike Fighter, leading Dircm manufacturer Northrop Grumman has begun company-funded development of a directed infrared countermeasures system that can fit within a limited volume and preserve the aircraft's stealth characteristics, but be more powerful than existing Dircms.

The traditional defense against heat-seeking missiles—still used on most helicopters and transports and all fighters—is to dispense decoy flares. But in the late 1980s and early 1990s, third-generation heat-seeking missiles emerged that could discriminate flares. This led to development of Dircm, which directs a modulated infrared signal into the missile seeker to confuse its guidance.

Dircm reset the battleground and gave defenders a new ability to adapt to evolving threats. “Dircm can overcome seeker technology as it evolves,” says Jeff Palombo, Northrop senior vice president and general manager for land and self-protection systems. “An aircraft does not run out of Dircm, as it does flares. And Dircm is not visible.”

After an initial generation of lamp-based Dircms, introduced in 1999, Northrop fielded the first laser-based systems in 2003. The company delivered around 1,000 of these “small laser-transmitter assembly” systems before switching to the still smaller Guardian laser transmitter. Since 2007, more than 2,000 Guardian systems have been delivered. “There has not been an event on any aircraft equipped with a Northrop Grumman Dircm,” Palombo says. “That is over 800 aircraft.”

New applications in the pipeline for the company's laser jammers include the Boeing P-8A and KC-46A and Sikorsky CH-53K in the U.S., and AgustaWestland AW101 and Airbus Military A400M in Europe, plus a range of head-of-state aircraft. The company developed a podded Dircm for commercial aircraft, but while an expected requirement to protect U.S. Civil Reserve Air Fleet aircraft flying into combat zones did not emerge, the Air National Guard is installing the Guardian pod on some Boeing KC-135 tankers.

Northrop is now developing its next generation of laser jammers under the U.S. Army's Common Infrared Countermeasures (Circm) program. In competition against BAE Systems, the company is in the technology development phase, having delivered systems for live-fire testing by the Army. A request for proposals for the engineering and manufacturing development program is expected early in 2014.

Circm is required to weigh 85 lb. or less, so it can be carried by helicopters as small as the Army's Bell OH-58D/F Kiowa Warrior armed scout. Northrop's system is its first to use a quantum cascade laser (QCL), a type of semiconductor laser that offers greater reliability and scalability. While Circm will expand the addressable market for directional infrared countermeasures, the U.S. closely controls export of the technology, and competitors are emerging on the international market.

These include Europe's Selex ES, which supplies Northrop with the pointer/tracker systems, or jam heads, for both its large-aircraft Dircm and its Circm design. Developed as a private venture, Selex's Miysis Dircm is aimed at smaller aircraft, helicopters and unmanned aircraft, and competes with the Mini-Music system developed by Elbit—a compact version of the Music fiber-laser system used on Israeli commercial aircraft.

Beyond Circm, Northrop sees the requirement to protect high-performance combat aircraft from infrared missiles. “There is no Dircm on fast jets today, but we believe the requirement is there, and coming quickly, and that the first opportunity will be on the F-35,” says Palombo.

Protecting a fast-moving fighter is “much different” than jamming missiles launched at slow-flying helicopters and transports. “For the first time, the requirements include air-to-air missiles, 9g maneuvers and small volumes. Heat dissipation will require liquid cooling,” he notes.

Northrop plans to begin testing a company-funded prototype of the Threat Nullification Defensive Resource (ThNDR) system in its integration laboratory by year-end. The timing for development of a laser missile jammer to equip the F-35 “is still in question,” Palombo says, “but we want to get out in front of the requirement.”

A Dircm is not part of the requirement for the initial, Block 3-standard F-35 now in development. But draft requirements already exist and, according to Northrop, a laser jammer is now expected to be part of the Block 5 update. This is scheduled for early in the 2020s.

The system must meet low-observability (LO) requirements and be packaged to fit in a confined space inside the F-35. But it will have a smaller, more-powerful laser than current Dircm systems and require liquid cooling, says Palombo.

The ThNDR, which includes the laser, beam-steering and LO window, is packaged to fit inside volume available alongside sensors for the F-35's distributed aperture system (DAS). There would be two jam heads, one on top and one underneath the aircraft to provide spherical coverage with minimal impact on the outer mold line.

The Northrop-developed DAS, which has six infrared sensors positioned to provide a 360-deg. view around the aircraft, would provide missile warning—detecting and declaring incoming threats and cueing the fine-tracking jam head to track the incoming missile and jam its seeker. Tests in the system-integration lab will look at challenges such as the high-speed hand off of targets between the upper and lower pointer/trackers as the F-35 rolls at rates of up to 17 deg./sec., he says.

Northrop is evaluating lasers from three suppliers, and is looking at QCL technology. The laser will be more powerful than in previous Dircms, to counter a wider range of air- and ground-launched threats. Working with the U.S. government, Northrop is developing ways to defeat air-to-air missiles. This involves understanding missile-seeker and tracking characteristics and their jamming susceptibilities, testing real missile seekers in fly-out engagement simulations and developing digital models.

Beyond the stealthy F-35, and Lockheed Martin F-22, Northrop sees requirements for a podded version of the fast-jet Dircm to protect non-stealthy combat aircraft such as the Boeing F-15 and Lockheed F-16. “It can be put in a self-contained pod, and it can be air-cooled,” Palombo says.