U.S. Navy Wants Long-Range Guided Artillery Shell For Hitting Moving Targets

The planned 155mm artillery round will use a combination of guidance systems, but is entirely “GPS-Free.”

byJoseph Trevithick|
U.S. Navy photo


The U.S. Navy is leading developing a new 155mm artillery round capable of destroying moving targets on land or at sea that could end up in use across three services, including the U.S. Army and Marine Corps. More importantly, the precision munitions will not use GPS, making them useful even in GPS denied environments. 

The Office of Naval Research (ONR), the Naval Surface Warfare Center Dahlgren Division (NSWC Dahlgren), and the Army Research Laboratory (ARL) have been coordinating on the project, blandly titled the Moving Target Artillery Round. The MTAR acronym has apparently lent itself to a more colorful program logo featuring a minotaur throwing the notional projectile. The Navy and its partners are still ironing out the full requirements, having just put out an official contracting notice looking for information from prospective industry partners in May 2017. The plan is to have the project formally up and running sometime in 2019.

As of May 2017, the Navy was envisioning a 155mm round able to strike moving opponents on the surface, whether they are on dry land or out at sea, at ranges roughly between 40 and 60 miles, according to a briefing Sanford Steelman, a program manager at NSWC Dahlgren, presented at the National Defense Industry Association’s 2017 Armament Systems Forum & Firing Demonstration. Though not specified, to get these ranges from existing howitzers, the projectiles would need to be boosted by a rocket or another significant additional propellant source. The presentation also included a conceptual description of a fire mission by a howitzer battery against a land target.

The MTAR project logo., USN

The first phase involves the crew of an M777A1 155mm howitzer receiving and process the request for fire support, which would include uploading the relevant target information into the MTAR. This is the same basic procedure for Army and Marine Corps gunners employing the GPS-guided M982 Excalibur projectile. With Excalibur, the appropriate coordinates must be transferred into the guidance unit via before troops send it down range.

The conceptual MTAR firing sequence., USN

In the case of MTAR, the idea is to use a separate radar system to track the projectile and point it to the target’s general area. During flight, inertial navigation would keep it going in the right direction. In the final stage, a manned aircraft, drone, or troops on the ground would use a laser designator to aim the projectile at the exact target. Though not specified in Steelman’s brief, the round’s seeker would have to include a so-called “laser-lead” capability to calculate how far ahead of a moving target it needs to fly in order to actually hit the mark. Both the Army and Marines might find the shells useful for taking out opponents driving anything from tanks to technicals.

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The new guided 155mm round will be able to work in any Army or Marine Corps M777A1 howitzer. As such, it will undoubtedly be compatible with the M109A6 Paladin and M109A7 Paladin Integrated Management (PIM) self-propelled 155mm systems. Conceivably, existing counter-fire radars that can track incoming fire and locate enemy artillery batteries could supply the initial direction for the projectile, reducing the amount of additional new equipment troops would need to employ the final, production ammunition. The presentation featured a picture of the electronically-scanned AN/TPQ-36 Firefinder, one such system, as the notional example. Updated versions of the "Q-36" use an inertial navigation system to plot the path of projectiles to locate their launchers, which could also aid in MTAR’s guidance.

Two Q-36 radars., US Army

But by far the most significant of MTAR’s features is that, unlike Excalibur or a number of other precision artillery ammunition already in service or in development, its guidance does not involve GPS in any way. The Navy specifically says this is to make sure troops and sailors can continue providing precise artillery support in a “satellite/network denied environment.” This would be a situation where the connection to the space-based navigation system is somehow broken, whether by jamming the signal, spoofing an inaccurate location, or someone just physically knocking down the satellites.

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Though this might sound like the plot of a Hollywood movie or the beginnings of a conspiracy theory, the Pentagon has become increasingly worried about the very real threats to GPS coverage. With so much of day-to-day combat heavily reliant on GPS, along with satellite-based communications and sensor systems, even a brief disruption could have wide-range impacts. These issues seem to be among the main driving factors behind the Defense Advanced Research Projects Agency’s (DARPA) XS-1 space plane project. And The War Zone's own Tyler Rogoway has long been calling attention to the dangers of new technologies designed to attack targets in space and wrote the following in December 2016:

Cyber warfare may be grabbing all the headlines lately, but space – the place where so much of America’s unique combat capability is enabled from – is the US military’s glaring Achilles Heel. China and Russia are rapidly developing new capabilities to destroy, disable, blind or even hijack American satellites in orbit in an attempt to level the playing field should a peer-state conflict breakout. The US is slowly trying to adapt to this new reality by spinning up new ways to navigate and target in GPS-denied combat environments – as well as coming up with new communications techniques that work around reliance on satellite relays.

Marines fire an M777 howitzer in Iraq in 2008., USMC

Unfortunately, the Navy's GPS-free solution isn't perfect. Lasers are notorious sensitive to environmental factors such as cloud cover, dust, and smoke, which can break up the beam or block it entirely. The Army has been well aware of this issue from years of experience with the M712 Copperhead laser-guided shell. The service had adopted this round specifically to attack tanks and other armored vehicles. With terminal laser-guidance only, Copperhead had a "glide mode" that allowed the shell to fly a flatter trajectory, keeping it below heavy cloud cover that could impair its targeting system. 

MTAR's initial and mid-course guidance would make it more flexible than Copperhead, but still be less so than a true "dual-mode" weapon with both GPS- and laser-guidance systems on board. Units would probably need to stock both these rounds and existing GPS-guided projectiles in order to cover all the expected target sets. This relative simplicity might keep the cost down and wide-spread fielding could potentially reduce the unit cost of each round even more, as both the Army and Marines buy stockpiles for all of their towed and mobile 155mm howitzers.  The overall percentage is always an important consideration and might make the projectile a viable option for the 155mm Advanced Gun System (AGS) weapons on the Navy’s high-tech Zumwalt-class stealth destroyers, too. The ONR has already designated the eventual formal project a “Future Naval Capability” program.

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The Navy has had a desperate need for alternative projectiles or weapons for the Zumwalts since the service canceled future purchases of the advanced Long-Range Land Attack Projectile (LRLAP) in 2016. Each of these had a mind-boggling sticker price of $800,000. This decision left the ships’ main guns with literally no ammunition. Three services buying the MTAR could only drive down the cost even more and a cheap guided round, however imperfect, could provide at least an interim solution for the Zumwalt's glaring armament problem. 

To make the round even more attractive to the Navy, Steelman’s brief noted that there were already plans to develop a discarding sabot that would allow crews to fire the guided munitions from 5-inch naval guns, standard on all Arleigh Burke-class destroyers and Ticonderoga-class cruisers. Of course, the proposed MTAR wouldn't have the range of the LRLAP, which were able to hit targets up to 100 miles away. Depending on its minimum range, however, it might be more useful against small, waterborne attackers in a swarm scenario, and above all else can provide an over-the-horizon precision strike capability against moving targets that could be designated by a ship's MH-60 Seahawk helicopter or MQ-8 Fire Scout helicopter drone. Even small boats equipped with laser designators could act as forward targeting nodes, and of course the round would be especially useful for supporting troops ashore. 

MTAR is just one of a suite of guided munitions that the Navy is exploring as part of a broader project it calls “Enhanced Expeditionary Engagement Capability,” or E3C. Other developments included continued work on 81mm and 60mm mortar rounds with combination GPS- and laser-guidance systems. The goal of E3C is to “demonstrate the ‘art of the possible’ in fire support technologies for USMC weapons, through an ongoing series of integrated system firing demonstrations,” Steelman explained in his presentation.

If all goes to plan, “possible” may include a precision, long-range artillery round free of the tether of GPS before the end of 2022.

Contact the author: joe@thedrive.com