The US Navy's submarine service is easily the most powerful ever fielded in the history of submarine warfare. Consisting of Los Angeles, Seawolf, Virginia and Ohio-class boats, this all-nuclear force is silent and deadly, prowling the world's waterways without anybody the wiser.
While the unlimited range, the quiet and very stealthy nature of these combat vessels makes them incredibly dangerous, it's their armament that plays the biggest part in making them the most lethal killing machines traversing the oceans today.
Every American submarine in service today is armed with the Mark 48 Advanced Capability torpedo, the latest and greatest in underwater warfare technology. These "fish" are designed to give submarine commanders a flexible tool that can be used to destroy enemy vessels, or serve as remote sensors, extending the operational capabilities of submarines far beyond what they're inherently able to do while on patrol.
A Mark 48 being loaded onto the USS Annapolis, a Los Angeles-class submarine (Photo US Navy)
As you can probably tell, these next-level torpedoes have undergone a considerable evolution from their predecessors of decades past. Advanced on-board computers, propulsion systems and explosives combine within the frame of the Mark 48 to make it a highly lethal one-shot-one-kill solution for every American submarine commander serving today.
Like many weapons fielded on modern battlefields the Mark 48 ADCAP is "smart," meaning that it can function autonomously with a high degree of efficiency and effectiveness, allowing for unparalleled accuracy. When fired in anger, the Mark 48 rushes to its target using a "pumpjet propulsor" that can push the torpedo to speeds estimated to be above 50 mph underwater, though the actual stats are classified.
The high speeds were originally a major requirement to allow American subs to chase down fast-moving Soviet attack submarines, which were also capable of diving deep and out of range, thanks to reinforced titanium pressure hulls.
The Mark 48 is initially guided by the submarine which deploys it through a thin trailing wire connected to the boat's targeting computers and sensors. Upon acquiring its target, the wire is cut and the torpedo's internal computers take over, guiding the underwater weapon home with precision.
US Navy torpedo retrievers secure a Mark 48 to the deck of their boat (Photo US Navy)
In days past, when torpedoes missed their target, they would likely keep swimming on until exhausting their fuel supply, or until they detonated. That's not the case with the Mark 48, however.
When the Mark 48 misses its target, it doesn't stop hunting. Instead, it circles around using its onboard computers to reacquire a lock and attempt a second attack.
This time, it probably won't miss.
When the Mark 48 reaches its target, that's when all hell breaks loose. Though earlier torpedoes would be programmed to detonate upon impacting or nearing the hull of an enemy vessel, the Mark 48 takes a different path... literally.
When attacking surface vessels, it travels below the keel of the ship, which is generally unprotected, detonating directly underneath. The massive pressure bubble that results from the gigantic explosion doesn't just slice through the bulk of the target boat - it also literally lifts the ship out of the water and snaps the keel, essentially breaking its back.
The US Navy is in the process of exploring upgrades to the Mark 48, including diminishing the noise generated by its engine in order to make it nearly undetectable to its targets, and enhancing its in-built detection and targeting systems.
Currently, the Navy fields the Common Broadband Advanced Sonar System variant of the Mark 48 - the 7th major upgrade the torpedo has undergone over its service history.