The U.S. Army and Israeli Ministry of Defense are moving forward with plans to develop a battlefield-deployable high-energy laser called Mobile Tactical High Energy Laser (MTHEL) capable of shooting down short-range rockets, artillery rounds, mortars, and eventually cruise missiles. After choosing a Northrop Grumman Space Technology (Redondo Beach, CA) design for the MTHEL in August 2003, military officials are now on the verge of awarding a sole-source contract to Northrop Grumman to begin building and testing the first mobile prototype.
The MTHEL is a follow-on project to the THEL (Tactical High Energy Laser), which Northrop Grumman began developing in 1996 and which has since been tested in numerous field studies at White Sands Missile Range in New Mexico. Under the current four-year (2003–2007), $118 million MTHEL project, the goal is to refine and ruggedize the original chemical-laser weapon so that it is air-transportable and can be towed behind a truck, called the Heavy Expanded Mobility Tactical Truck (HEMTT), for use in battlefield situations.
"MTHEL will bring speed-of-light defense to the battlefield, but it will act and feel like any other air-defense system," said Joe Shwartz, MTHEL program manager at Northrop Grumman. "It will be operated by soldiers and supported in the field, mostly by the use of existing maintenance and logistical infrastructure."
Responding to terrorist threats from rockets fired into cities along the northern border of Israel, the United States and Israel embarked on the THEL program in 1996; it moved from initial concept to operational system in four years for a total cost of less than $275 million. In June 2000, the THEL conducted the first successful shoot-down of an operational Katyusha rocket in flight. Since then it has recorded 29 Katyusha kills, including single and multiple rocket salvos. The THEL is fully operational as a transportable system, but it was determined that there is also a need for a mobile system that can operate not only on a standard Army truck but also on unmanned aerial vehicles and rotary- and fixed-wing aircraft.
Deuterium fluoride has power
The original THEL design includes a 3.8-µm-emitting deuterium fluoride (DF) laser, target-acquisition radar, automated battle management/command, control and communications, and pointer tracker for fire and beam control (Northrop Grumman declined to disclose any other system specs at this time). In the mobile design, replacement laser sources—the "ammunition"—would be towed alongside the MTHEL for quick and efficient reloading of the effector (the firing unit). Northrop Grumman chose the DF laser because there are currently no solid-state lasers that can achieve the power levels "sufficient to do the job," according to Pat Caruana, vice president for missile defense at Northrop Grumman Space Technology. In addition to the THEL/MTHEL, Northrop Grumman has been building laser modules for the Airborne Laser, which also requires high-energy intensity and beam quality to find and engage its targets (see Laser Focus World, January 2004, p. 105).
"Lasers on the battlefield provide the ability to engage very fast high-flying threat objects," Caruana said. "With the laser, once you find the object, there is not the usual kinetic energy time. Once the laser finds the target and gets a beam on it, we can generally kill it. And with the laser, you can do preferential defense, so it not only detects the object but determines which object has higher potential to do damage to your assets."
According to Caruana, another advantage of the DF system is that the cost per kill comes down appreciably because once the laser expends its initial power, as long as the source remains hooked up to the effector unit, it is lasing. Part of the next phase of the prototype program is to refine the concept so that it includes a way to supply the system with fresh laser sources while the system is operating.
"We have done considerable work in refining the laser modules to bring them down in size," Caruana said. "In the process, we have been able to achieve efficiencies that are almost twice what we had in the first testbed."
Also critical to the MTHEL is the software. According to Caruana, the MTHEL algorithms allow the system to detect an incoming object in near-real time and can determine the most vulnerable point on the object for single or multiple incoming threats.