Weapon Systems

Army Long-Range Persistent Surveillance: Detecting air threats without being seen


The US Army's new passive sensor technology is designed to help combat threats from the skies while remaining covert.

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Soldiers of the 69th Air Defense Artillery Regiment practice Air Defense techniques at Camp Arifjan, Kuwait January 19, 2017. [US Army]
Soldiers of the 69th Air Defense Artillery Regiment practice Air Defense techniques at Camp Arifjan, Kuwait January 19, 2017. [US Army]

The Army Long-Range Persistent Surveillance (ALPS), a passive, long-range sensor system, is designed to detect threats from the skies without itself being detected, allowing soldiers to "see without being seen."

The system, which can detect cruise missiles, fixed and rotary wing aircraft, and unmanned aerial system (UAS) threats, is still in its prototype phase.

The Army plans to bring in the ALPS system in Fiscal Year 2026, Brig. Gen. Frank Lozano, the US Army program executive officer for missiles and space, told Defense News in August.

ALPS is heavily classified and many characteristics about the new sensor system remain unreleased.

It can be configured to meet a user's needs, Inside Defense reported in 2019, citing the Army. The most common configuration is a transportable, 100-foot trailed tower and CONEX-based processing shelter.

Some sources have reported that the ALPS database has the capacity to store and recognize the signatures of about 700 different types of targets, including Russian cruise missiles used in the Syria conflict.

Its design means that it is inherently more stealthy and, in turn, survivable.

Passive sensors refer to a wide variety of devices that measure and report on whatever they detect in their local environment.

They differ from active sensors that emit energy to scan objects and areas, which can reveal the sensor's location.

Remaining covert while collecting information is of key value for military applications.

"Silent and covert awareness of neighbors' activities is a long-standing ideal for military commanders," Nation Shield, a military magazine published by armed forces of the United Arab Emirates, reported in November 2019.

"Indeed, the need for early warning and detailed target identification supports fast decision-making in successful military and security operations."

ALPS manufacturer Leidos Dynetics Group, which is also developing advanced air defense sensors for the US Marine Corps based on its Army counterpart, said in June the new class of sensors can detect enemy threats without emitting electromagnetic signals that may give away their location.

"As we speak, we've got a dozen systems out there across the world actively feeding the air picture into command-and-control nodes and helping troops stay safe," Matt Becker, Leidos Vice President and Division Manager for Integrated Tech Solutions, said in a statement.

360-degree, long-range surveillance

The Army confirmed in 2019 that it was fielding ALPS.

The prototype systems were deployed to US Indo-Pacific Command, US European Command and US Central Command to meet the combatant commands' needs and to conduct an operational assessment, Lt. Gen. James Dickinson, then-head of the Army Space and Missile Defense Command/Army Forces Strategic Command, said at the time.

ALPS was also intended to be integrated into the Army's Integrated Air and Missile Defense Battle Command System (IBCS).

IBCS, which connects sensors and effectors into one command-and-control system, is "the centerpiece of the US Army's modernization strategy for air and missile defence capability," according to manufacturer Northrop Grumman.

Once fully integrated into the IBCS, ALPS will provide "360-degree, long-range surveillance" against threats, Dickinson said.

Col. Chuck Worshim, who was then the Army's project manager for cruise missile defense systems, told Inside Defense in 2019 that ALPS, in its science and technology phase, has shown "a great passive capability to help inform the overall air picture."

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