Special: inside helicopter laser mine detection

The Airborne Laser Mine Detection System (ALMDS) is changing the way the Navy conducts counter-mine operations by allowing it to function in less accessible places, which reduces the danger to crewmembers.

Traditionally, the MH-53E Sea Dragon helicopter has been the Navy’s key asset in counter-mine operations. Tthe ALMDS is compact enough to be installed on the smaller MH-60S Seahawk helicopter, according to the Navy.

"ALMDS allows us to take airborne mine countermeasures technology to these smaller helicopters that can fly from smaller ships allowing us to take mine countermeasures into places that may not have been accessible before," said Lt. Cmdr. Theodore Lemerande, the officer in charge of Laser Hawks said in a Navy statement.

The laser component of the ALMDS utilizes Light Detecting and Ranging (LIDAR) technology, which includes a laser, scanner, and laser receiver, in this case, the streak tubes. According to the National Oceanic and Atmospheric Administration, LIDAR technology is based on the emission of laser pulses, which the software then uses to measure the distance to various micro-points on earth. This measurement data is combined with other recorded data to produce a 3D map the earth’s surface.

"It's a laser-driven system that works like radar," said Lt. Cmdr. Theodore Lemerande, officer in charge of Laser Hawks. "It beams a laser down into the water and picks up reflections from anything it bounces off of. The system then registers the returned information and uses that data to produce a video image in order for technicians on the ground to determine what the object is."

Instead of a continuous scanning mechanism, the ALMDS uses the forward motion of the aircraft to capture the lasers’ return input, eliminating the need for a pause to allow for data streaming and processing. Northrop Grumman also reports that the lack of moving parts increases the durability of the ALMDS, reducing maintenance costs for the Navy.

The fact that the ALMDS has no towed sensor, and thereby requires no physical contact with the body of water that potentially contains mines, means that MH-60S crewmembers using the ALMDS are at less risk during counter-mine missions.

Paired with the MH-60S helicopter, the ALMDS has contributed to naval maneuvers and mine detection in littoral zones, or shallow areas where the seafloor geography and aquatic plants create constricted water ways that can become operational choke points.

ALMDS has also demonstrated its mine-detecting capabilities in areas that involve amphibious coordination. Amphibious operations are launched from the sea with the goal of introducing a landing force, and the ability to detect and destroy potential mine threats is key to the effectiveness of these missions, according to a Marine Corp publication on amphibious doctrine.

The ALMDS is smaller than previous systems because its total of nine subsystems are all mostly contained within a single pod that is reported by Northrop Grumman to be about nine feet long, 21 inches wide, and 805 pounds. It is attached via the Bomb Rack Unit 14 of the aircraft and data travels through primary and auxiliary cables to the operator console.

The nine subsystems include a Laser Transmitter Unit, Laser Electrical Unit, Pod Pressurization System, Environmental Control System, Power Distribution Unit, four Receiver Sensor Assemblies, Hardware Control Unit, and Pod Housing. The final subsystem is the Central Electronics Chassis (CEC), which VMETRO has produced for Northrop Grumman since 2006.

The CEC system is an image data processor that uses liquid to cool down the high-speed, multi-processor. The CEC is crucial to the ALMDS because its cooling systems allow for a degree of computing power that enables comprehensive data collection, and then rapid analysis of that data in order to make informed decisions under threat, according to Northrop Grumman’s announcement of the VMETRO contract.

LIDAR technology can gather data that is either topographic, which involves using an almost infrared laser for land-based terrain mapping, or bathymetric, which uses a green laser light to map the seafloor terrain through water. The ALMDS primarily uses the bathymetric method, as it is focused on locating and neutralizing near-surface moored sea mines.

"This system provides state-of-the-art technology to the warfighter” said Mine Warfare Program Office Program Manager, Donna Carson-Jelley. “Because LIDAR data is much different than legacy RADAR and SONAR data, I've required my team to pay particular attention to training and getting the end-user involved early…Fleet feedback on a low-rate, initial production test can have tremendous impact on the end result, and the pilot and aircrew feedback loop is very healthy within the ALMDS program," she explained.

“The key thing that we’re excited about with the system is that it’s affordable, it covers the given body of three dimensional water space in a very fast, efficient manner…and it can search that given water space without exposing the sailor to the danger of the mine in that water space,” said Mark Skinner, Vice President, Directed Energy Military Aircraft Systems at Northrop Grumman.

The Helicopter Sea Combat Squadron 26, Detachment 2 has operationally tested the ALMDS in the 5^th Fleet Area of Responsibility (AOR), which encompasses the Persian Gulf, Red Sea, Arabian Sea, and part of the Indian Ocean.

Now, the ALMDS deployed in the 5^th Fleet AOR is helping the Navy more effectively carry out its mission of keeping the sea open for international trade.

“It’s a very exciting time for the ALMDS program because we learn so much when the fleet sailors get their hands on the system and operate it on a day to day basis on deployment overseas in support of fleet operations. They’re going to find a lot of things out about the system and that will inform our decision on future improvements to the system,” said Skinner.

Northrop Grumman’s latest statement also reports that the ALMDS system was successfully installed and test-operated in a UH-60M Blackhawk helicopter. This initiative could represent the first steps toward using ALMDS technology for land-based mine detection, likely achieved by further developing the topographical LIDAR method.